System, device, and method for high quality ion beam formation

Abstract

To provide a system, a device, and a method for suitable high quality ion beam formation.SOLUTION: Embodiments of a system, a device, and a method relate to a beam system. An exemplary beam system includes a charged particle source configured to generate a beam of charged particles, a preaccelerator system configured to accelerate the beam, and an accelerator configured to accelerate the beam from the preaccelerator system. The preaccelerator system can focus the beam as it propagates from the source to an input aperture of the accelerator. The preaccelerator system can further reduce or eliminate source disturbances or damage caused by backflow traveling from the accelerator toward the source.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application is a continuation of U.S. Provisional Application No. 63 / 044,310, entitled "SYSTEMS, DEVICES, AND METHODS FOR HIGH QUALITY ION BEAM FORMATION," filed June 25, 2020; U.S. Provisional Application No. 62 / 895,203, entitled "EINZEL LENS FOR LOW ENERGY ION BEAM TRANSPORT," filed September 3, 2019; and U.S. Provisional Application No. 62 / 894,106, entitled "SYSTEMS AND METHODS FOR GAS PUFF BEAM SYSTEMS," filed August 30, 2019, all of which are incorporated herein by reference in their entireties. This application claims priority to U.S. Provisional Application No. 62 / 894,220, entitled "SYSTEMS AND METHODS FOR FAST BEAM POSITION MONITORING," filed on August 30, 2019, and U.S. Provisional Application No. 62 / 894,290, entitled "SYSTEMS AND METHODS FOR FAST BEAM POSITION MONITORING," filed on August 30, 2019.

[0002] The subject matter described herein generally relates to systems, devices, and methods for forming high quality ion beams for tandem accelerator systems. [Background technology]

[0003] Boron neutron capture therapy (BNCT) is a modality for the treatment of various types of cancer, including some of the most difficult types. BNCT is a technique that uses boron compounds to selectively target tumor cells to treat them while sparing normal cells. A substance containing boron is injected into the bloodstream, and the boron concentrates in the tumor cells. The patient then receives radiation therapy with neutrons (e.g., in the form of a neutron beam). The neutrons react with the boron, killing the tumor cells while reducing harm to the surrounding normal cells. Long-term clinical studies have demonstrated that a beam of neutrons with an energy spectrum within 3 to 30 kiloelectron volts (keV) is preferred for achieving more efficient cancer treatment while reducing the radiation burden to the patient. This energy spectrum or range is frequently referred to as epithermal.

[0004] Most conventional methods for the generation of epithermal neutrons (e.g., epithermal neutron beams) are based on nuclear reactions of protons with either beryllium or lithium (e.g., a beryllium or lithium target). In both cases, the energy spectrum of the resulting neutrons is shifted to higher energies and therefore requires moderation. Such moderation of neutrons to the required energy (e.g., within the epithermal spectrum), along with the formation of the required neutron beam for BNCT, is conventionally achieved using a beam shaping assembly (BSA).

[0005] Cyclotron accelerators accelerate charged particles along a helical path outward from the center of the accelerator. The particles are held in a helical trajectory by a static magnetic field and accelerated by a rapidly varying (high frequency) electric field. The reaction of protons with a beryllium target is characterized by a high yield of neutrons, which allows the maintenance of a relatively low proton beam current within the limits achievable on, for example, a proton cyclotron accelerator. The energy of the proton beam is also within the limits of a cyclotron accelerator. Hence, neutron sources based on cyclotron accelerators and beryllium targets are characterized by a high neutron yield. However, the energy spectrum of the resulting neutrons is shifted towards higher energies, requiring substantial de-energization in a composite BSA, as explained above. Such composite BSAs are inefficient for de-energizing the neutrons and forming the required neutron beam for ideal BNCT applications.

[0006] High-energy accelerators are usually expensive and the higher energy protons and neutrons cause higher activation of the system components, making systems with beryllium targets less attractive for BNCT treatment centers.

[0007] The beam of epithermal neutrons formed in a cyclotron-based system with a beryllium target has a flux density comparable to that of a system with a lithium target. However, systems with a lithium target result in a lower energy proton beam, usually in the range of 1.9 to 3.0 megaelectron volts (MeV). Existing proton beam accelerators designed for lithium targets can be divided into two categories: RF-based accelerators and electrostatic accelerators.

[0008] RF-based accelerators: Typically, RF-based proton accelerators for the required energy range are based on radio frequency quadrupoles, or RFQs. RFQs are linear accelerators that focus and accelerate a continuous beam of charged particles with high efficiency while conserving emittance. Focusing and acceleration are performed by radio frequency (RF) electric fields. RFQ technology is well developed, but remains expensive and unattractively complex to manufacture and operate. Furthermore, it is difficult to build RFQ systems for average currents of 10 milliamps (mA) or higher.

[0009] Electrostatic accelerators: The required energy range is within reach for electrostatic accelerators. Electrostatic accelerators accelerate charged particles by exposing them to a static high-voltage potential. For example, high-voltage terminals are held at a static potential (also referred to as the acceleration voltage) of about several million volts. Electrostatic accelerators are usually substantially cheaper, more compact, and more energy efficient than other conventional solutions. Electrostatic accelerators also advantageously offer the ability to tailor the spectrum of the resulting neutrons by varying the proton beam energy.

[0010] Generating the required acceleration voltages above 2 megavolts (MV) in an electrostatic accelerator system using direct acceleration is very difficult, which limits the achievable energy of an ideal proton beam. The placement of the proton source at the high-voltage end of the electrostatic accelerator limits the ability to form an injected proton beam with low emittance, which limits the quality of the accelerated beam. Control and maintenance of the proton injector / source at the high-voltage end of the electrostatic accelerator is also very technically difficult.

[0011] A tandem accelerator is a type of electrostatic accelerator that may employ two-stage acceleration of ion particles using a single high-voltage terminal. A high voltage is used, for example, to create an increasingly positive gradient that is applied to an incoming negative beam to accelerate it, at which point the tandem accelerator converts the negative beam to a positive beam, and then a high voltage is used again to create a reversed, decreasingly positive gradient that accelerates (e.g., pushes) the positive beam out of the tandem accelerator. Because high voltages may be used twice, the generation of a proton beam with a particle energy of 3 MeV typically requires only an acceleration voltage of 1.5 MV, which is within the limits of modern technology for electrical insulation. Additionally, the ion source of a tandem accelerator is installed at ground potential, which makes it easier to maintain and control the ion source.

[0012] In ion beam systems utilizing plasma-based ion sources, ions are extracted from the boundary surface (called the meniscus) of the plasma. The shape and parameters of the boundary surface are characterized by the extracted current density, the local rate of ionization, recombination and diffusion, and a strong dependence on the applied electric field distribution. The nascent ion beam is typically highly divergent due to the low initial energy, distorted (the effect of the magnetic dipole, which separates electrons and ions of the same polarity), and suffers from space charge effects. As a result, various existing solutions face several shortcomings.

[0013] A single aperture source of negative hydrogen ions with sufficiently high current usually faces several challenges such as high initial beam divergence due to the conditions of high current beam generation, limited beam acceleration within the ion source aperture due to the high gas loading required for high current beam generation, and beam divergence due to the space charge of the beam, which is more pronounced for lower energy beam particles.

[0014] For these and other reasons, a need exists for improved, efficient, and compact systems, devices, and methods that provide high quality ion beams for tandem accelerator systems. Summary of the Invention [Means for solving the problem]

[0015] Exemplary embodiments of systems, devices, and methods for forming high-quality ion beams that can be used in various accelerator systems are described herein. The embodiments of the present disclosure are directed to beam systems, devices therein, and methods of use thereof. The exemplary beam system includes a particle source (e.g., an ion source) configured to generate particles in a beam form, a preaccelerator system configured to accelerate the particles from the source, and an accelerator configured to accelerate the particles from the preaccelerator system. The preaccelerator system can focus the beam as it propagates from the source to the input aperture of the accelerator. The preaccelerator system can further reduce or eliminate source disturbances or damage caused by backflow traveling from the accelerator toward the source.

[0016] Other systems, devices, methods, features, and advantages of the subject matter described herein will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. All such additional systems, methods, features, and advantages are intended to be included within this description, be within the scope of the subject matter described herein, and be protected by the accompanying claims. Features of the example embodiments should not be construed as limiting the appended claims in any way, even if an explicit recitation of those features is absent in the claims. The present invention provides, for example, the following: (Item 1) 1. A beam system comprising: a particle source configured to emit a beam of charged particles; a preaccelerator system configured to accelerate the charged particle beam from the particle source; an accelerator configured to accelerate the charged particle beam from a preaccelerator system; A beam system comprising: (Item 2) 2. The beam system of claim 1, wherein the particle source is an ion source and the charged particle beam is an ion beam comprising negative hydrogen ions. (Item 3) 2. The beam system of claim 1, wherein the preaccelerator system comprises at least one of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. (Item 4) 2. The beam system of claim 1, wherein the preaccelerator system comprises an electrostatic lens, a preaccelerator device, and a magnetic focusing device. (Item 5) 5. The beam system of claim 4, wherein the electrostatic lens is an Einzel lens, the preaccelerator device is a preaccelerator tube having multiple acceleration terminals, and the magnetic focusing device is a solenoid. (Item 6) 5. The beam system of claim 4, wherein the electrostatic lens is downstream of the particle source, the preaccelerator device is downstream of the electrostatic lens, and the magnetic focusing device is downstream of the preaccelerator device. (Item 7) The electrostatic lens is an Einzel lens, and the Einzel lens is two grounded electrodes coupled to each other in a spaced apart relationship; a bias electrode, the bias electrode being positioned between the two grounded electrodes and supported by an insulator extending therebetween, the bias electrode or one or more of the two grounded electrodes being configured for negative bias; 5. The beam system of item 4, comprising: (Item 8) 6. The beam system of claim 5, wherein the preaccelerator tube comprises a first preaccelerator tube terminal and a second preaccelerator tube terminal. (Item 9) 9. The beam system of claim 8, wherein the first preaccelerator tube terminal is electrically connectable to a first power supply source. (Item 10) 10. The beam system of claim 9, wherein the second preaccelerator tube terminal is electrically connectable to ground. (Item 11) 2. The beam system of claim 1, wherein the accelerator is a tandem accelerator comprising a plurality of input electrodes, a charge exchange device, and a plurality of output electrodes. (Item 12) 12. The beam system of claim 11, wherein the charged particle beam is a negative ion beam, the plurality of input electrodes are configured to accelerate the negative ion beam from the preaccelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the plurality of output electrodes are configured to accelerate the positive beam. (Item 13) Item 13. The beam system of item 12, further comprising a target device configured to form a neutral beam from the positive beam received from the tandem accelerator. (Item 14) 2. The beam system of claim 1, wherein the preaccelerator system is positioned adjacent to and downstream of the particle source. (Item 15) 5. The beam system of claim 4, wherein the preaccelerator device is positioned downstream of the electrostatic lens. (Item 16) 5. The beam system of claim 4, wherein the magnetic focusing device is positioned downstream of the preaccelerator device. (Item 17) 5. The beam system of claim 4, wherein the preaccelerator device is positioned downstream of one or more of the electrostatic lens or the particle source. (Item 18) 5. The beam system of claim 4, wherein the magnetic focusing device is positioned downstream of one or more of an Einzel lens, a preaccelerator tube, or the particle source. (Item 19) 2. The beam system of item 1, further comprising one or more vacuum pump chambers. (Item 20) 20. The beam system of claim 19, wherein a first vacuum pump chamber is positioned between the preaccelerator system and the accelerator. (Item 21) 21. The beam system of claim 20, wherein a second vacuum pump chamber is positioned between the particle source and the preaccelerator system. (Item 22) 2. The beam system of claim 1, wherein one or more vacuum pump chambers are positioned on the accelerator. (Item 23) 2. The beam system of claim 1, wherein the particle source comprises a wall having one or more filaments positioned adjacent thereto. (Item 24) 24. The beam system of claim 23, further comprising a first cooling device configured to cool the wall. (Item 25) 25. The beam system of claim 24, further comprising a second cooling device configured to cool the Einzel lens. (Item 26) 26. The beam system of claim 24 or 25, wherein the first and second cooling devices are configured to use a fluid coolant. (Item 27) 2. The beam system of claim 1, wherein the preaccelerator system is configured to focus the charged particle beam propagating from the particle source at an input aperture of the accelerator. (Item 28) 2. The beam system of claim 1, wherein the preaccelerator system is configured to defocus and collect an ionized backflow propagating from the accelerator towards the particle source. (Item 29) 2. The beam system of claim 1, wherein the preaccelerator system is configured to transition the particle beam from the particle source from a divergent state to a focused state. (Item 30) 2. The beam system of claim 1, wherein the preaccelerator system comprises an electrostatic lens configured to transition the particle beam from the particle source from a divergent state to a focused state. (Item 31) 31. The beam system of claim 30, wherein the electrostatic lens is controllable to adjust beam focusing or backflow defocus. (Item 32) 2. The beam system of claim 1, wherein the preaccelerator system comprises a magnetic focusing device that is controllable to adjust beam focusing or countercurrent defocusing. (Item 33) 2. The beam system of claim 1, wherein the preaccelerator system comprises a preaccelerator tube that is controllable to adjust beam focusing or backflow defocus. (Item 34) 34. The beam system of any of items 30-33, further comprising a plurality of power supplies configured to adjustably output variable power to the magnetic focusing device, the electrostatic lens, and the preaccelerator tube. (Item 35) 2. The beam system of claim 1, wherein the system is configured to accelerate the charged particles to their maximum cross-section before entering the accelerator. (Item 36) Item 36. The beam system of item 35, wherein the charged particles are negative hydrogen ions. (Item 37) Item 37. The beam system of item 36, wherein the system is configured to accelerate the charged particles to an energy of 100 keV prior to entry into the accelerator. (Item 38) Item 36. The beam system of item 35, wherein the system is configured to accelerate the charged particles to their maximum cross-section at a location within a preaccelerator tube of the preaccelerator system. (Item 39) Item 39. The beam system of item 38, wherein the location is within a central region of the preaccelerator tube. (Item 40) 2. The beam system of claim 1, further comprising a vacuum pump chamber configured to remove gas exiting the accelerator into the preaccelerator system. (Item 41) 2. The beam system of claim 1, wherein the particle source is positioned such that the charged particle beam is emitted along the same or a substantially similar axis transverse to the accelerator along which charged particles passing through the accelerator are accelerated. (Item 42) 2. The beam system of item 1, further comprising a control system. (Item 43) Item 43. The beam system of item 42, wherein the control system is configured to receive operating parameters or instructions from a computing device. (Item 44) Item 44. The beam system of item 43, wherein the control system is configured to transmit operational data to the computing device. (Item 45) 43. The beam system of claim 42, wherein the control system is configured to control at least one of a voltage applied to an electrode of the particle source, a voltage applied to an electrostatic lens of the preaccelerator system, a voltage applied to a preaccelerator device of the preaccelerator system, a voltage applied to a magnetic focusing device of the preaccelerator system, a voltage applied to the accelerator, a voltage output by a power supply of the beam system, adjusting a beam position for alignment, adjusting a beam focus position, or adjusting an amount of backflow defocus. (Item 46) 46. ​​The beam system of any of items 1-45, configured for use in boron neutron capture therapy (BNCT). (Item 47) 1. A method of operating a beam system, the method comprising: emitting a beam comprising charged particles from a particle source; accelerating the beam towards an accelerator using a preaccelerator system; accelerating the beam using the accelerator; A method comprising: (Item 48) Item 48. The method of item 47, wherein the preaccelerator system comprises one or more of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. (Item 49) Item 49. The method of item 48, wherein the electrostatic lens is an Einzel lens, the preaccelerator device is a preaccelerator tube with multiple accelerating terminals, and the magnetic focusing device is a solenoid. (Item 50) 48. The method of claim 47, wherein the accelerator is a tandem accelerator. (Item 51) Item 51. The method of item 50, wherein the tandem accelerator comprises a charge exchange device. (Item 52) Item 48. The method of item 47, wherein accelerating the beam towards the accelerator using the preaccelerator system includes accelerating the beam such that the charged particles reach their maximum cross-section prior to entering the accelerator. (Item 53) 53. The method of claim 52, wherein the charged particles are negative hydrogen ions. (Item 54) Item 53. The method of item 52, wherein the charged particles reach their maximum cross-section in a preaccelerator tube of the preaccelerator system. (Item 55) Item 48. The method of item 47, further comprising focusing the beam using the preaccelerator system. (Item 56) 48. The method of claim 47, further comprising adjusting power supplied to the preaccelerator system to control focusing of the beam. (Item 57) 57. The method of claim 56, wherein focusing the beam further comprises transitioning the beam from a divergent state to a focused state using the preaccelerator system. (Item 58) 57. The method of claim 56, wherein the beam is focused using one or more of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. (Item 59) Item 57. The method of item 56, wherein the preaccelerator system comprises an electrostatic lens, a preaccelerator device, and a magnetic focusing device. (Item 60) 60. The method of claim 59, wherein the electrostatic lens is downstream of the particle source, the preaccelerator device is downstream of the electrostatic lens, and the magnetic focusing device is downstream of the preaccelerator device. (Item 61) 60. The method of claim 59, further comprising adjusting power supplied to the preaccelerator device to control focusing of the beam. (Item 62) 60. The method of claim 59, further comprising adjusting power supplied to the magnetic focusing device to control the focus of the beam. (Item 63) adjusting the power supplied to the preaccelerator device to control focusing of the beam; adjusting power supplied to the magnetic focusing device to control the focus of the beam; 60. The method of claim 59, further comprising: (Item 64) Item 64. The method of item 63, wherein adjusting the power supplied to the magnetic focusing device to control the focus of the beam comprises adjusting the power supplied to the magnetic focusing device to focus the beam at an input aperture of the accelerator. (Item 65) Item 48. The method of item 47, wherein the particle source is positioned such that the beam is emitted along the same or a substantially similar axis transverse to the accelerator along which charged particles passing through the accelerator are accelerated. (Item 66) Item 66. The method of item 65, wherein the particle source is one of a volume type source and a surface type source. (Item 67) 67. The method of any of claims 47-66, further comprising the step of defocusing backflow from the accelerator using the preaccelerator system. (Item 68) Item 68. The method of item 67, wherein the backflow comprises an ionized background gas. (Item 69) Item 68. The method of item 67, further comprising the step of adjusting power supplied to the preaccelerator system to control defocusing of the counterflow. (Item 70) 70. The method of claim 69, further comprising adjusting power supplied to the preaccelerator system to cause backflow to be collected by one or more components of the beam system. (Item 71) 70. The method of claim 69, further comprising adjusting the power supplied to the preaccelerator system to cause backflow to avoid backflow sensitive components of the particle source. (Item 72) 72. The method of claim 71, wherein the reflux sensitive component is a filament. (Item 73) Item 68. The method of item 67, wherein the backflow is defocused using one or more of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. (Item 74) Item 68. The method of item 67, wherein the preaccelerator system comprises an electrostatic lens, a preaccelerator device, and a magnetic focusing device. (Item 75) 75. The method of claim 74, wherein, relative to the progression of the beam, the electrostatic lens is downstream of the particle source, the preaccelerator device is downstream of the electrostatic lens, and the magnetic focusing device is downstream of the preaccelerator device. (Item 76) 75. The method of claim 74, further comprising adjusting power supplied to the preaccelerator device to control defocusing of the counterflow. (Item 77) 75. The method of claim 74, further comprising adjusting power supplied to the magnetic focusing device to control defocusing of the backflow. (Item 78) adjusting power supplied to the preaccelerator device to control defocusing of the counterflow; adjusting power supplied to the magnetic focusing device to control defocusing of the reflux flow; 75. The method of claim 74, further comprising: (Item 79) 79. The method of claim 47-78, wherein the particle source is positioned such that the beam is emitted along the same or a substantially similar axis transverse to the accelerator along which charged particles passing through the accelerator are accelerated. (Item 80) Item 48. The method of item 47, further comprising the step of performing a vacuum removal of gas. (Item 81) Item 81. The method of item 80, further comprising the step of performing a vacuum removal of gas at a first location between the preaccelerator system and the accelerator and at a second location between the particle source and the preaccelerator system. (Item 82) Item 82. The method of item 81, wherein accelerating the beam towards the accelerator using the preaccelerator system includes accelerating the beam such that the charged particles reach their maximum cross-section prior to entering the accelerator. (Item 83) 48. The method of claim 47, further comprising using a control system of the beam system to control at least one of a voltage applied to an electrode of the particle source, a voltage applied to an electrostatic lens of the preaccelerator system, a voltage applied to a preaccelerator device of the preaccelerator system, a voltage applied to a magnetic focusing device of the preaccelerator system, a voltage applied to the accelerator, a voltage output by a power supply of the beam system, adjusting a beam position for alignment, adjusting a beam focus position, or adjusting an amount of backflow defocus. (Item 84) receiving operating parameters or instructions from a computing device using a control system; or transmitting operational data to the computing device using the control system. Item 48. The method of item 47, further comprising one or more of the following: (Item 85) 85. The method of claim 84, wherein the control system is configured for one or more of wireless or wired communication. (Item 86) 86. The method of any of items 47-85, further comprising applying the beam to a target. (Item 87) 87. The method of claim 86, wherein the particle source is an ion source and the charged particles are negative hydrogen ions. (Item 88) Item 88. The method of item 87, further comprising converting the beam from a negative hydrogen ion beam to a proton beam in the accelerator. (Item 89) Item 89. The method of item 88, wherein applying the beam to a target comprises applying the proton beam to a neutron generating target. (Item 90) 90. The method of any of claims 47-89, further comprising using the beam system in boron neutron capture therapy (BNCT). (Item 91) 1. A method for defocusing a counterflow in a beam system, the method comprising: evacuating the gaseous neutrons from the tandem accelerator; biasing a preaccelerator system coupled to the tandem accelerator, the preaccelerator system configured to defocus positive ionized gas accelerated in a direction opposite to the accelerated beam of the beam system by a magnetic field; A method comprising: (Item 92) Item 92. The method of item 91, wherein the preaccelerator system comprises one or more of a preaccelerator tube, an Einzel lens, a magnetic focusing device, or a solenoid. (Item 93) 93. The method of claim 92, further comprising electrically coupling the preaccelerator tube to a first power supply at a first preaccelerator tube terminal and to ground at a second preaccelerator tube terminal. (Item 94) Item 92. The method of item 91, wherein the preaccelerator system is positioned adjacent to and downstream from the ion source. (Item 95) Item 93. The method of item 92, wherein the preaccelerator tube is mounted adjacent to and downstream of the Einzel lens. (Item 96) 93. The method of claim 92, wherein the magnetic focusing device is mounted adjacent to and downstream of the preaccelerator tube. (Item 97) Item 93. The method of item 92, wherein the preaccelerator tube is positioned downstream of one or more of an Einzel lens or an ion source. (Item 98) Item 93. The method of item 92, wherein the Einzel lens is positioned downstream of the ion source. (Item 99) 93. The method of claim 92, wherein the magnetic focusing device is positioned downstream of one or more of an Einzel lens, the preaccelerator tube, or an ion source. (Item 100) Item 92. The method of item 91, wherein a first vacuum pump chamber is positioned between the preaccelerator system and the tandem accelerator. (Item 101) Item 101. The method of item 100, wherein a second vacuum pump chamber is positioned between the ion source and the preaccelerator system. (Item 102) Item 92. The method of item 91, wherein one or more vacuum pump chambers are positioned on an upper surface of the tandem accelerator. (Item 103) Item 95. The method of item 94, further comprising cooling a backplate of the ion source using a first cooling device, the backplate comprising one or more filaments. (Item 104) Item 95. The method of item 94, further comprising cooling the Einzel lens using a second cooling device. (Item 105) Item 105. The method of item 103 or 104, wherein one or more of the first cooling device or second cooling device comprises water cooling. (Item 106) Item 93. The method of item 92, further comprising using a first power supply to bias the magnetic focusing device and adjust the beam focusing or backflow defocusing properties of the magnetic focusing device. (Item 107) Item 93. The method of item 92, further comprising using a second power supply to bias the Einzel lens and adjust the beam focusing or backflow defocusing properties of the Einzel lens. (Item 108) Item 93. The method of item 92, further comprising using a third power supply to bias the preaccelerator tube and adjust the beam focusing or backflow defocusing properties of the preaccelerator tube. (Item 109) Item 95. The method of item 94, further comprising positioning the ion source so that ions are emitted along the same or substantially similar axis transverse to the tandem accelerator along which ions passing through the tandem accelerator are accelerated. (Item 110) receiving operating parameters or instructions from a computing device using a control system; or transmitting operational data to the computing device using the control system. Item 92. The method of item 91, further comprising one or more of the following: [Brief description of the drawings]

[0017] Details of the subject matter described herein, both as to its structure and operation, may become apparent by inspection of the accompanying drawings, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, and emphasis may instead be placed on illustrating the principles of the subject matter. Moreover, all illustrations are intended to convey concepts, and relative sizes, shapes, and other detailed attributes may be depicted diagrammatically, rather than literally or precisely.

[0018] [Figure 1A] FIG. 1A is a schematic diagram of an exemplary embodiment of a neutron beam system for use with embodiments of the present disclosure.

[0019] [Figure 1B] FIG. 1B is a schematic diagram of an exemplary embodiment of a neutron beam system for use in boron neutron capture therapy (BNCT).

[0020] [Diagram 2] FIG. 2 illustrates an exemplary preaccelerator system or ion beam implanter for use with embodiments of the present disclosure.

[0021] [Figure 3A] FIG. 3A is a perspective view of the ion source and ion source vacuum box shown in FIG.

[0022] [Figure 3B] FIG. 3B is an exploded perspective view depicting an exemplary embodiment of the Einzel lens shown in FIG. 3A.

[0023] [Figure 4] FIG. 4 illustrates an exemplary preaccelerator tube for use with embodiments of the present disclosure.

[0024] [Diagram 5]FIG. 5 illustrates a cross section of an exemplary ionization curve.

[0025] [Figure 6] FIG. 6 illustrates the operation of an exemplary preaccelerator system or ion beam implanter for use with embodiments of the present disclosure.

[0026] [Figure 7] FIG. 7 illustrates an exemplary beam implanter system employing a vertical ion source and a curved magnet.

[0027] [Figure 8] FIG. 8 further illustrates the operation of an exemplary preaccelerator system or ion beam implanter for use with embodiments of the present disclosure.

[0028] [Figure 9] FIG. 9 illustrates an exemplary ion source backplate for use with embodiments of the present disclosure.

[0029] [Figure 10] FIG. 10 illustrates a block diagram of a system in which embodiments of the present disclosure may operate.

[0030] [Figure 11] FIG. 11 illustrates an exemplary computing device that may be specially configured according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Detailed Description Before the present subject matter is described in detail, it is to be understood that the present disclosure is not limited to particular embodiments described, which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, as the scope of the present disclosure will be limited only by the appended claims.

[0032] The term "particle" is used broadly herein, and unless otherwise limited, may be used to describe an electron, a proton (or an H+ ion), or a neutron, as well as species having more than one electron, proton, and / or neutron (e.g., other ions, atoms, and molecules).

[0033] The above and other limitations resulting in high beam divergence and low beam energy make it difficult to design an ion implanter suitable for operation with a particle accelerator. Taking a tandem accelerator as an example, low energy negative ions (e.g., H-ions) injected into the tandem accelerator may create unfavorable conditions in the first acceleration gap of the tandem accelerator. In practice, the output energy of a negative ion source is typically limited by 20-40 keV. When such negative ions are injected into the first acceleration gap of a tandem accelerator, which typically has an acceleration voltage of about 200 kilovolts (kV), the negative ions typically reach an energy of about 100 keV in the center of the first acceleration gap.

[0034] An energy of 100 keV corresponds to the approximate maximum of the ionization cross section for negative hydrogen ions (e.g., as shown in FIG. 5). The ionization cross section represents a measurement of how large a particular particle appears relative to other particles while traveling through space. Accelerators can often have trace amounts of background gas present in the near-vacuum environment. For tandem accelerators, background gas (e.g., argon neutrons) can be intentionally introduced by a gaseous charge exchange device used to modify the charge of the incoming beam in the center of the tandem accelerator. Beam particles such as H-ions can ionize this background gas, and this ionization can be substantial or concentrated. In such tandem accelerators with gaseous charge exchange targets, the resulting relative high pressure and larger ionization cross section of the background gas can mean that H-ions are more likely to collide with the background gas in the first acceleration gap of the tandem accelerator.

[0035] Furthermore, the concentrated ionization in the first acceleration gap of the tandem accelerator induces a beam-sustained plasma discharge in the first acceleration gap, which leads to several disadvantages, including: (i) high-voltage breakdown of the tandem accelerator, rendering the accelerator inoperable for undesirable durations (e.g., hundreds of seconds); (ii) reduced voltage on the first acceleration gap, resulting in overloading of the high-voltage power supply, leading to beam defocusing and reduced beam energy; (iii) overheating of the electrodes of the tandem accelerator; (iv) formation of a concentrated backflow of accelerated positive ions, overheating the particle source and disrupting its operation; and (v) generation of bremsstrahlung radiation, irradiating the surfaces of the high-voltage insulators of the tandem accelerator and reducing its high-voltage strength. Bremsstrahlung radiation is radiation produced by a charged particle due to its acceleration caused by the electric field of another charged particle.

[0036] The high current of the negative ion beam may also require substantial efforts to focus the negative ion beam into the input aperture of the tandem accelerator. Typically, negative ion beam injectors with currents higher than 5 milliamps (mA) are complex and have several focusing magnetic elements and gas or plasma filled beam lines to compensate for the space charge of the ion beam. In such an embodiment, as depicted in FIG. 7, the negative ion beam injector includes a vertical ion source and utilizes bending magnets to focus the resulting ion beam toward the input aperture. Such systems suffer from disadvantages, including low beam quality and elliptical beams. Elliptical beams are undesirable for tandem accelerators, and therefore such implementations require significantly complex beam handling to achieve beam quality (e.g., substantially non-elliptical or nearly circular cross section) for tandem accelerators. Furthermore, any accelerator with a gas filled beam line may suffer substantial loss of beam current due to charge exchange, even in a near vacuum environment.

[0037] Exemplary embodiments of systems, devices, and methods for a preaccelerator system for use with a particle accelerator are described herein. A particle accelerator is a general example, and the embodiments described herein can be used with any type of particle accelerator or in any particle accelerator application involving the production of a charged particle beam at a defined energy to feed the particle accelerator. The present preaccelerator system or ion beam injector embodiments are suitable for providing a negative particle beam to a tandem accelerator, but this is only an exemplary type of accelerator. The preaccelerator embodiments described herein can be implemented in particle accelerators used as scientific tools such as for nuclear physics research, particle accelerators used in industrial or manufacturing processes such as semiconductor chip manufacturing, accelerators for material property modification (such as surface treatment), particle accelerators for food irradiation, and particle accelerators for pathogen destruction in medical sterilization. The embodiments can also be used in imaging applications such as cargo or container inspection. Also, as another non-exhaustive example, embodiments can be used in particle accelerators for medical applications, such as medical diagnostic systems, medical imaging systems, or radiation therapy systems.

[0038] One such radiation therapy system is a BNCT system. For ease of explanation, many embodiments described herein will be so implemented in the context of a neutron beam system for use in BNCT, but the embodiments are not limited to neutron beam or BNCT applications only. The embodiments of the present disclosure allow for the configuration of an accelerator system (also referred to herein as a pre-accelerator system) for generating a proton beam with suitable parameters for a source of neutrons for BNCT using a neutron generating target such as lithium (Li) or beryllium (Be).

[0039] For efficient generation of epithermal neutrons on a lithium target, a beam of protons with energies between 1.9 and 3.0 MeV is desirable. Formation of a neutron beam with favorable flux density over a reasonably short treatment time in such applications may also involve a proton beam current above 5 mA. To employ a tandem accelerator system in such applications, a source of negative ions of hydrogen may be preferred. A source of negative hydrogen ions with sufficiently high current may have a high emittance, which may make it difficult to build a negative ion beam injector for a tandem accelerator while maintaining a suitable beam quality. The proposed configuration overcomes this and other difficulties and provides a compact, efficient negative ion beam source (e.g., of negative hydrogen ions) with high beam quality.

[0040] The embodiments of the present disclosure can increase the energy of the charged particles immediately upon their incidence from a charged particle source, such as an ion source, which effectively leads to a reduction in space charge, which causes ion beam particle divergence to decrease with increasing particle energy, eliminating or reducing the need for gas or plasma filled beamlines.

[0041] The disclosed embodiments can enable a short focal length, which makes the present preaccelerator or ion beam implanter system relatively more compact than conventional systems. The disclosed embodiments can further reduce backflow (see, e.g., discussion of FIG. 5 ) to the extent that the need to move the ion implanter off the accelerator beam axis is eliminated (and thus beam bending magnets are included upstream of the accelerator to substantially reorient the implanted ion beam onto the proper axis). Note that the use of the terms "upstream" and "downstream" refers to the direction of beam travel, not the direction of backflow.

[0042] An embodiment of the present disclosure relates to the use of a preaccelerator tube with dimensions selected such that a focal length of 500 to 1,500 millimeters (mm) is achieved at an acceleration voltage of 60 to 180 kV. Thus, fine tuning of the beam focusing spot to the location of the input aperture of the tandem accelerator can be achieved by positioning a single additional magnetic element (e.g., a solenoid) downstream of the preaccelerator tube.

[0043] The embodiments of the present disclosure allow for a reduced size of the negative ion beam at the input aperture of the tandem accelerator. In fact, the smaller the input size of the beam, the smaller its size at the center of the tandem accelerator. The smaller radius of the beam at the center of the tandem accelerator allows for a reduction in the inner diameter of the charge exchange device, which leads to a reduction in the gas flow required to generate a sufficiently high gas pressure in the charge exchange device for efficient charge conversion of the beam particles. Typically, an efficiency of 90-95% is considered acceptable for a gas charge exchange device. The lesser gas flow reduces the background pressure in the tandem accelerator and, as a result, increases its reliability.

[0044] Compared to conventional approaches, embodiments of the present disclosure can provide, among other things, the following additional advantages: higher reliability of the tandem accelerator due to a lower probability of high voltage insulation breakdown, higher high voltage strength of the insulators in the tandem accelerator, lower load on the first accelerating gap resulting in a more uniform and stable acceleration rate in the tandem accelerator, lower or suppressed backflow from the tandem accelerator to the negative ion source, reduced generation of bremsstrahlung radiation in the first accelerating gap, and lower thermal load on the electrodes of the tandem accelerator.

[0045] Features of embodiments of the present preaccelerator system solve several problems associated with, for example, the physics of negative ion sources and tandem accelerators.

[0046] The embodiments of the present disclosure may be useful for any type of electrostatic accelerator of negative ions with beam currents greater than a few milliamps. The embodiments disclosed herein may have optional additional elements, including ion optics and beam diagnostics, before, in, or after the preaccelerator system, as required by a particular application.

[0047] The embodiments of the present disclosure can be used for neutron beam systems (NBS) that provide a sustained or modulated proton beam. The proton beam can have a wide range of energies and currents. For example, in some embodiments, the proton beam has a particle energy in the range of 1.9-3.0 MeV with a beam current of 5-15 mA. In other embodiments, the proton beam has an energy and / or current outside of these ranges. The beam can be directed at a lithium target to generate a neutron beam, or the NBS can be used with targets having other materials for neutron generation, such as beryllium, instead of lithium.

[0048] In some embodiments, the ion source generates a beam of negative ions of hydrogen with a current of up to 15 mA. The beam particles can be accelerated in the ion source to an energy of 30 keV (or higher). The ion source can be connected to a preaccelerator system (with one or more intervening components), which provides additional acceleration of the negative ion beam particles to energies of 120-150 keV (or higher). The beam can also be focused in the preaccelerator system with a focal length corresponding to the distance to the input aperture of the tandem accelerator input chamber, e.g., a distance of less than 1 meter (m). The preaccelerator system can include an electrostatic lens (e.g., an Einzel lens), a preaccelerator device (e.g., a preaccelerator tube with multiple terminals), and / or a magnetic element (e.g., one or more solenoids) for accelerating the ion beam to higher energies upon entering the tandem accelerator.

[0049] The electrostatic lens of the preaccelerator system can be positioned between the ion source and the preaccelerator tube such that the electrostatic lens is downstream of the grounded lens of the ion source. The electrostatic lens can reduce the divergence of the ion beam from the ion source and can also divert and collect ionized backflow particles.

[0050] A magnetic element (or magnetic focusing device) of the preaccelerator system can be positioned between the preaccelerator tube and the tandem accelerator to fine-tune the beam toward a focal spot. The magnetic element can be, for example, a solenoid.

[0051] The ion beam injection scheme disclosed herein can enable operation with significant reduction of charged particle backflow or without significant charged particle (e.g., secondary ion) backflow. This allows for the placement of the charged particle source such that the supplied particles are emitted along the same or substantially the same axis across the accelerator along which the particles passing through the accelerator are accelerated. Because the charged particle source can be emitted on the same axis used by the accelerator, no significant beam deflection is required (except for relatively minor adjustments to fine-tune alignment), and thus the beam distortion inherent in such significant deflection can be avoided. Thus, the present injection scheme allows operation of the neutron beam system without beam deflection magnets between the charged particle source and the tandem accelerator that change the angle of the beam from one major axis to another (e.g., by 20 degrees or more).

[0052] 1A is a schematic diagram of an exemplary embodiment of a beam system for use with embodiments of the present disclosure. Here, the beam system 10 includes a source 22, a low energy beam line (LEBL) 190, an accelerator 40 coupled to the low energy beam line (LEBL) 190, and a high energy beam line (HEBL) 50 extending from the accelerator 40 to a target assembly housing a target 196. The LEBL 190 is configured to transfer the beam from the source 22 to the accelerator 40, which is configured to accelerate the beam. The HEBL 50 transports the beam from the output of the accelerator 40 to the target 196.

[0053] FIG. 1B is a schematic diagram illustrating an exemplary neutron beam system 10 for use in boron neutron capture therapy (BNCT) according to an embodiment of the present disclosure. The neutron beam system 10 includes a preaccelerator system 20 forming at least a portion of a LEBL, serving as a charged particle beam injector as shown in FIG. 2, a high voltage (HV) tandem accelerator 40 coupled to the preaccelerator system 20, and a high energy beam line 50 extending from the tandem accelerator 40 to a neutron target assembly 200 housing a neutron production target. In this embodiment, the beam source 22 is an ion source, and the charged particle beam is a negative ion beam prior to conversion to a proton beam in the tandem accelerator 40. It should be understood that the neutron beam system 10 as well as the preaccelerator system 20 can also be used for other applications such as cargo inspection and others, and are not limited to BNCT.

[0054] The pre-accelerator system 20 (also referred to herein as a charged particle beam injector or ion beam injector) is configured to transport the ion beam from the ion source 22 to the input (e.g., input aperture) of the tandem accelerator 40, and thus also acts as the LEBL 190.

[0055] Powered by a high voltage power supply 42 coupled thereto, the tandem accelerator 40 is capable of producing a proton beam with an energy generally equal to twice the voltage applied to acceleration electrodes located within the tandem accelerator 40. The proton beam energy level can be achieved by accelerating a beam of negative hydrogen ions from the input of the tandem accelerator 40 to the innermost high potential electrode, stripping two electrons from each ion, and then accelerating the resulting protons downstream with the same applied voltage.

[0056] The high energy beamline 50 can transport the proton beam from the output of the tandem accelerator 40 to a neutron generating target in a neutron target assembly 200 located at the end of a beamline branch 70 that extends into a patient treatment room. The system 10 can be configured to direct the proton beam to any number of one or more targets and associated treatment areas. In this embodiment, the high energy beamline 50 includes three branches 70, 80, and 90 and extends into three different patient treatment rooms. In this embodiment, the high energy beamline 50 includes a pump chamber 51, quadrupole magnets 52 and 72 to prevent beam defocusing, dipole or bending magnets 56 and 58 to steer the beam into the treatment room, a beam corrector 53, diagnostics such as current monitors 54 and 76, a high speed beam position monitor 55 section, and a scanning magnet 74.

[0057] The design of the high energy beam line 50 depends on the configuration of the treatment facility (e.g., one-storey treatment facility, two-storey treatment facility, and the like). The beam can be delivered to the target assembly 200 (e.g., located near the treatment room) using the bending magnet 56. A quadrupole magnet 72 can then be included to focus the beam to a certain size at the target. The beam then passes through one or more scanning magnets 74, which provide lateral movement of the beam on the target surface in a desired pattern (e.g., spiral, curved, stepped in rows and columns, combinations thereof, and others). The beam lateral movement can help achieve a smooth and uniform time-averaged distribution of the proton beam on the lithium target, prevent overheating, and make neutron generation as uniform as possible within the lithium layer.

[0058] After entering the scanning magnet 74, the beam can be delivered into a current monitor 76, which measures the beam current. The target assembly 200 can be physically separated from the high energy beamline volume using a gate valve 77. The main function of the gate valve is to separate the target from the vacuum volume of the beamline while loading the target and / or replacing the used target with a new one. In an embodiment, the beam does not have to be bent 90 degrees by the bending magnet 56, but rather goes straight to the right and then enters the quadrupole magnet 52, located in the horizontal beamline. The beam can then be bent by another bending magnet 58 to the angle required depending on the room configuration. Otherwise, the bending magnet 58 can be replaced with a Y-shaped magnet to split the beamline into two directions for two different treatment rooms located on the same floor.

[0059] FIG. 2 illustrates an example of a preaccelerator system or ion beam implanter for use with embodiments of the present disclosure. In this example, the preaccelerator system 20 includes an Einzel lens 30 (not visible in FIG. 2 but depicted in FIGS. 3A-3B), a preaccelerator tube 26, and a solenoid 510, and is configured to accelerate the negative ion beam implanted from the ion source 22. The preaccelerator system 20 is configured to provide acceleration of the beam particles to the required energy for the tandem accelerator 40 and to provide overall focusing of the negative ion beam to match the input aperture area at the input aperture or entrance of the tandem accelerator 40. The preaccelerator system 20 is further configured to minimize or defocus backflow as it passes from the tandem accelerator 40 through the preaccelerator system to reduce damage to the ion source and / or the possibility of backflow reaching the filament of the ion source.

[0060] In an embodiment, the ion source 22 can be configured to provide a negative ion beam upstream of the Einzel lens 30, where the negative ion beam continues to pass through the preaccelerator tube 26 and a magnetic focusing device (e.g., a solenoid) 510. The solenoid 510 can be positioned between the preaccelerator tube and the tandem accelerator and can be electrically coupled to a power supply. The negative ion beam passes through the solenoid 510 to the tandem accelerator 40.

[0061] The preaccelerator system 20 may also include an ion source vacuum box 24 for removing gases and a pump chamber 28, which, along with the preaccelerator tube 26 and other elements described above, are part of a relatively low energy beamline leading to the tandem accelerator 40. The ion source vacuum box 24, in which the Einzel lens 30 may be positioned, extends from the ion source 22. The preaccelerator tube 26 may be coupled to the ion source vacuum box 24 and a solenoid 510. The vacuum pump chamber 28 for removing gases may be coupled to the solenoid 510 and the tandem accelerator 40. The ion source 22 serves as a source of charged particles, which may be accelerated, conditioned, and ultimately used to produce neutrons when delivered to a neutron producing target. Although exemplary embodiments will be described herein with reference to an ion source producing a negative hydrogen ion beam, the embodiments are not limited as such and other positive or negative particles may also be produced by the source.

[0062] The preaccelerator system 20 can have zero, one, or multiple magnetic elements for purposes such as focusing the beam and / or adjusting its alignment. For example, any such magnetic elements can be used to align the beam with the beamline axis and acceptance angle of the tandem accelerator 40. The ion vacuum box 24 may have ion optics positioned therein.

[0063] Generally, there are two types of negative ion sources 22, namely, surface type and volume type, which differ in the mechanism of generation of negative ions. The surface type generally requires the presence of cesium (Cs) on a specific internal surface. The volume type relies on the formation of negative ions within the volume of a high current discharge plasma. Although both types of ion sources can deliver the desired negative ion current for applications related to tandem accelerators, the surface type negative ion source is not desirable for modulation. That is, for modulation of negative ion beams in the embodiments described herein, a volume type negative ion source (e.g., not employing cesium (Cs)) is preferred.

[0064] Turning to FIG. 3A, the ion source vacuum box 24 of the ion beam implanter 20 can include an Einzel lens 30 positioned therein. As shown in detail in FIG. 3B, the Einzel lens 30, which can be mounted downstream of the grounded lens 25 of the ion source 22 in the vacuum box 24, includes a mounting plate 32, two grounded electrodes 34 mounted to the mounting plate 32 and coupled to each other in a spaced apart relationship using a mounting rod 35, and a powered (biased) electrode 38 positioned between the two grounded electrodes 34. The electrodes 34 and 38 are fabricated in the form of a cylindrical aperture and assembled to have an axial axis coinciding with the beam path. The powered electrode 38 is supported by an isolator (or insulator) 36 that extends between the grounded electrodes or apertures 34.

[0065] The isolation isolator 36 may have a geometric design configured to inhibit the development of avalanches and suppress streamer formation and propagation that may result in flashover formation. The geometric design of the isolation isolator 36 may, in part, screen the external electric field on the insulator surface that drives the avalanche and effectively increases the path length. Additionally, the material of the insulator / isolator 36 tends to reduce sputtering effects, loss of negative ions on the surface, volumetric contamination, and the formation of conductive coatings on the insulator or isolator surface that lead to reduced electrical strength.

[0066] Functionally, the action of the Einzel lens 30 on the beam of charged particles advancing from the ion source 22 is similar to that of an optical focusing lens on a beam of light. That is, the Einzel lens 30 focuses the incoming divergent beam into a spot at the focal plane. However, now the electric field formed between a pair of powered electrodes 38 and two grounded electrodes 34 determines the focusing strength (focal length) of the Einzel lens.

[0067] Mounting the Einzel lens 30 downstream of the ion source ground lens 25 reduces the beam free space transport when the beam is subject to divergence due to inherent space charge.

[0068] The dimensions of the axisymmetric or substantially axisymmetric design of the Einzel lens 30 are optimized to avoid direct interaction of the extracted ions with the exposed surface of the Einzel lens 30 .

[0069] In operation, a negative polarity bias of the Einzel lens 30 results in higher focused power than a positive bias polarity. Also, in operation, the method of power delivery to the Einzel lens 30 provides a gradual voltage growth instead of instantaneous voltage application, which reduces the rate of growth (dE / dt) of the electric field at existing microprotrusions on the surface of the Einzel lens 30 that are involved in plasma formation, e.g., via an explosive ejection mechanism. Such disruption of plasma formation improves the electric intensity.

[0070] Negative bias potentials for Einzel lenses in high background pressures are typically not possible due to electrical breakdown. The configuration of the exemplary embodiments of the Einzel lenses provided herein allows for application of negative bias voltages high enough for 100% current utilization without electrical breakdown.

[0071] FIG. 4 illustrates an exemplary preaccelerator tube 26 for use with embodiments of the present disclosure. The exemplary preaccelerator tube 26 can be cylindrical in shape and can include a first preaccelerator tube end 26A and a second preaccelerator tube end 26B. In an embodiment, the first preaccelerator tube end 26A includes a fixture (e.g., a terminal or electrode) that protrudes outward from the inner cylindrical structure of the preaccelerator tube. In an embodiment, the second preaccelerator tube end 26B includes a fixture (e.g., a terminal or electrode) that protrudes outward from the inner cylindrical structure of the preaccelerator tube. That is, the fixture that protrudes outward from the inner cylindrical structure of the preaccelerator tube is cylindrical in shape but may have a diameter larger than that of the inner cylindrical structure. In an embodiment, the preaccelerator tube 26 includes a plurality of preaccelerator tube terminals 27-1, 27-2, 27-3, 27-4, 27-5, 27-6 that are uniformly spaced from a first preaccelerator tube end 26A to a second preaccelerator tube end 26B. The first preaccelerator tube end 26A may be referred to as the proximal preaccelerator tube end 26A in relation to the second preaccelerator tube 26B, which in some implementations is the distal preaccelerator tube end 26B. Each pair of adjacent preaccelerator tube terminals (e.g., preaccelerator tube terminals 27-1, 27-2, 27-3, 27-4, 27-5, 27-6) may have one or more resistors connected therebetween, and the resistors may have the same (preferably) or different resistance values. In an embodiment, a first terminal 27-1 at the first preaccelerator tube end 26A can be electrically coupled to a first power supply, while a second terminal 27-2 at the second preaccelerator tube end 26B can be electrically coupled to ground. Thus, voltage can be uniformly distributed across the preaccelerator tube 26. In an embodiment, the preaccelerator tube 26 can be configured to control the focusing of the negative ion beam passing therethrough such that the negative ion beam at least remains on a parallel path or remains persistently focused while passing through the preaccelerator tube 26.

[0072] In an embodiment, the beam focusing properties of the preaccelerator tube 26 are determined by the length and inner diameter of the preaccelerator tube 26. The combination of length and inner diameter is selected to achieve a focal length / distance of 500-1,500 mm at an accelerating voltage of 60-180 kV. The length L, width W, and inner diameter of the preaccelerator tube may vary according to a given application for which the preaccelerator tube is to be used.

[0073] 6 illustrates beam focusing in an exemplary preaccelerator system for use with embodiments of the present disclosure. An ion source 22 is optionally housed in an ion source enclosure 500. The ion source 22 includes multiple electrodes, such as a plasma electrode 320, a ground lens (e.g., or accelerator electrode) 310, and an extraction electrode 330. The ion source 22 is coupled with an Einzel lens 30, and a negative ion beam is injected or propagated from the ion source 22 through the Einzel lens 30, the preaccelerator tube 26, and a solenoid 510 to the input aperture of the tandem accelerator 40.

[0074] The ion source 22 can be electrically coupled to a first terminal of a power supply PS3 at an accelerator electrode (e.g., or a grounded lens) 310, which is in turn electrically coupled to an enclosure of the ion source 22 at a second terminal. Biasing of the ion source 22 at the accelerator electrode (e.g., or a grounded lens) 310 configures the preaccelerator system 20 to maintain and propagate a negative ion beam when such beam is passed from the ion source 22. The plasma electrode 320 of the ion source 22 can be electrically coupled to a power supply PS1, and the extraction electrode 330 of the ion source 22 can be electrically coupled to a modulator (not shown), which is in turn electrically coupled to another power supply (not shown). The biasing of the plasma electrode 320 enables the ion source 22 to maintain a plasma within the ion source 22 and to be used for extraction into a negative ion beam when the extraction electrode 330 is biased. When the extraction electrode 330 is biased, the negative ion beam is passed or propagated from the ion source 22 towards the tandem accelerator 40. When the extraction electrode 330 is not biased, the negative ion beam is not passed or propagated from the ion source 22 along the tandem accelerator 40. The preaccelerator tube 26 may be biased at the first preaccelerator tube terminal 27-1 to a power supply PS1 and at the second preaccelerator tube terminal 27-2 to ground.

[0075] As discussed above, the tandem accelerator 40 is powered by a high voltage power supply PS5 coupled thereto and is capable of producing a proton beam with an energy generally equal to twice the voltage applied to an accelerating electrode located within the tandem accelerator 40. The power supply PS5 may be regulated by a feedback loop (not shown) whereby voltage stability within the tandem accelerator 40 is maintained.

[0076] FIG. 8 is a schematic block diagram of an exemplary embodiment of the preaccelerator system 20 in operation, depicting the ability of the preaccelerator system 20 to focus a negative ion beam 600. As can be seen, the beam 600 diverges in response to passing from the ion source 22 to the Einzel lens 30 (as shown from travel point P0 to travel point P1 in FIG. 8). The Einzel lens 30 is negatively biased to reduce the divergence of the beam 600 and provides beam focusing. Here, the Einzel lens 30 transitions the beam 600 from a diverging form to a converging form. The beam 600 again begins to diverge after exiting the lens 30, but remains constrained to approximately the same space between the source 22 and the preaccelerator tube 26 (e.g., from travel point P1 to travel point P2 in FIG. 8). The pre-accelerator tube 26 can be configured to further provide beam focusing to aid in focusing the negative ion beam 600 (e.g., from travel point P2 to travel point P3 in FIG. 8). The solenoid 510 can be biased to provide fine adjustment of the beam focusing to further aid in focusing the negative ion beam 600 (e.g., from travel point P3 to travel point P4 in FIG. 8) so that the negative ion beam 600 is of appropriate quality and focus size when it reaches the input aperture of the tandem accelerator 40. Controlling the bias on the solenoid 510 further allows fine adjustment of the beam focusing to ensure that the beam is adequately and accurately aimed at the input aperture of the tandem accelerator 40. Control of the power supply PS1 allows for coarse adjustment of the negative ion beam aimed at the input aperture of the tandem accelerator. Control of the power supply PS2 allows for fine adjustment of the adjustment of the negative ion beam aimed at the input aperture.

[0077] 8 also illustrates the counterflow defocusing operation of the exemplary embodiment of the preaccelerator system 20. As discussed above, low energy negative ions injected into a tandem accelerator create unfavorable conditions in the first acceleration gap of the tandem accelerator. In conventional systems, when a negative ion beam is injected into the first acceleration gap (e.g., G1) of a tandem accelerator, the ions typically reach an energy of about 100 keV in the center of the first acceleration gap.

[0078] The use of a gaseous medium (e.g., argon, nitrogen) in the charge exchange device of the tandem accelerator 40 creates a potential for the charge exchange gas to become ionized by the beam. Gaseous neutrons emerge from the charge exchange device in the center of the tandem accelerator when the gas is pumped, for example, into the charge exchange tube, stealing electrons from the negative ion beam (e.g., H- ions) and generating protons (e.g., H+ ions). The pressure of the background gas in a tandem accelerator with a gaseous charge exchange device is often relatively high, and the larger particle cross section (e.g., 100 keV in FIG. 5) that occurs in the first acceleration gap (e.g., G1) of the tandem accelerator means that negative hydrogen ions are more likely to collide with the background gas in the first acceleration gap of the tandem accelerator 40 and subsequently become ionized, which can lead to harmful effects such as arcing and breakdown. Furthermore, as gaseous neutrons travel back from the charge exchange device in the center of the tandem accelerator through the preceding acceleration gaps (e.g., G4, G3, G2, G1), ionization of the background gas occurs in the inner gap as well as the first acceleration gap.

[0079] In this embodiment, the ions of the negative ion beam reach an energy of about 100 keV at the approximate midpoint of the preaccelerator tube 26 (e.g., at some point between travel points P2 and P3 in FIG. 8, as opposed to, for example, inside the first accelerating gap G1 of the tandem accelerator). This is because fewer gaseous neutrons are present in the center of the preaccelerator tube 26 due to the configuration of the preaccelerator system 20 as well as the vacuum pump chamber (not shown) located between the preaccelerator system 20 and the tandem accelerator 40. The location at which the beam reaches the maximum cross-sectional energy of the beam's component particles may vary from the midpoint of the preaccelerator tube 26, and other such locations upstream of the input aperture of the tandem accelerator are also within the scope of the present subject matter (e.g., a location proximate end 26A or 26B of the preaccelerator tube 26, a location within the solenoid 510, a location within the Einzel lens 30, between the aforementioned components being examples of such).

[0080] Despite the above-mentioned improvements over existing systems for backflow in the first acceleration gap of the tandem accelerator, the preaccelerator system 20 may still suffer from backflow 610 passing through the system originating from the tandem accelerator 40 to which the preaccelerator system 26 provides the negative ion beam 600. The backflow is positive ionized gas accelerated by the magnetic field in the opposite direction to the accelerated beam. Gaseous neutrons traveling back from the charge exchange device through the preceding acceleration gap (e.g., G4, G3, G2, G1) represent particles that can potentially become ionized (through collisions) and backflow. Vacuum removal of a significant amount of the gaseous neutrons originating from the tandem accelerator 40 results in a reduction of possible particles that can backflow.

[0081] Thus, the components of the preaccelerator system 26 are also configured to minimize, defocus, or eliminate the backflow 610 as it passes through the preaccelerator system 26 to reduce the possibility of damage to the ion source 22 and / or to eliminate the possibility of the backflow reaching the filament of the ion source 22. Any biased components, including the Einzel lens 30, the preaccelerator tube 26, and / or the solenoid 510, can defocus the backflow 610. For example, the solenoid 510 can defocus the backflow, the amount or direction of defocus can be controlled by adjustment of the voltage applied to the solenoid 510 (e.g., by the second power supply PS2), which allows fine tuning of the solenoid 510 contribution towards beam focusing as well as backflow defocus.

[0082] Similarly, adjustment of the control of the bias of the preaccelerator tube 26 and the Einzel lens 30 assists in defocusing the backflow 610. That is, the preaccelerator tube 26 and the Einzel lens 30 may be independently controlled to achieve a desired degree of focusing of the beam 600 and defocusing of the backflow 610 for its minimization.

[0083] As shown in Figure 8, the counterflow 610 is defocused or redirected from the beam axis (e.g., from travel point P4 to travel point P2 in Figure 8) as it travels through the solenoid 510 and the preaccelerator tube 26. The counterflow may be collected by any component of the beam system, whether or not the component is biased. As shown here, a portion of the counterflow is collected by a cooling device 520, which is configured to cool an electrode of the Einzel lens 30.

[0084] Once the backflow 610 reaches the ion source 22, it is defocused to reduce or eliminate potential damage to the ion source 22, and the cooling device 660 further reduces or eliminates the backflow 610 as it reaches the upstream housing (e.g., backplate) 650 of the ion source 22. FIG. 9 illustrates an exemplary ion source backplate assembly for use with embodiments of the present disclosure. In an embodiment, the backplate assembly 650 includes a filament for generating a plasma and generating negative hydrogen ions from the ion source 22. In an embodiment, the backplate assembly 650 is optionally cooled using a cooling device 660 (e.g., water cooling) to prevent the backflow 610, which may strike the backplate assembly 650 at the backflow contact point 670, from reaching the filament. This ensures stability of the ion source 22 and eliminates reduced reliability of the ion source 22 and preaccelerator system 20 due to the backflow 620 from a gap in the tandem accelerator 40 and the backflow 610 traveling through the preaccelerator system 20.

[0085] 10 is a block diagram illustrating an example system 3000 in which embodiments of the present disclosure may operate. For example, the illustrated example system 3000 includes a preaccelerator system 3001, one or more computing devices 3002, and a tandem accelerator system 3003. In an embodiment, the preaccelerator system 3001 and the tandem accelerator system 3003 may collectively be part of an example neutron beam system (e.g., system 10, above). In such an embodiment, the neutron beam system 10 may employ one or more control systems with which the one or more computing devices 3002 may communicate to interact with the systems and components of the neutron beam system 10. Each of these devices and / or systems are configured to communicate with each other directly (not shown) or via a local network, such as network 3004.

[0086] The computing devices 3002 may be embodied by various user devices, systems, computing apparatuses, and the like. For example, a first computing device 3002 may be a desktop computer or workstation associated with a particular user, while another computing device 3002 may be a laptop computer associated with a particular user, and yet another computing device 3002 may be a mobile device (e.g., a tablet or smart device). Each computing device 3002 may be configured to communicate with the pre-accelerator system 3001 and / or the tandem accelerator system 3003, for example, through a user interface accessible via the computing device. For example, a user may run a desktop application on the computing device 3002, which is configured to communicate with the pre-accelerator system 3001 and / or the tandem accelerator system 3003.

[0087] By using the computing device 3002 to communicate with one or more of the pre-accelerator system 3001 or the tandem accelerator system 3003, a user may provide operating parameters for any of the systems according to embodiments described herein. In an embodiment, the pre-accelerator system 3001 may include a control system 3001A, whereby the pre-accelerator system 3001 may receive and apply operating parameters from the computing device 3002. In an embodiment, the tandem accelerator system 3003 may include a control system 3003A, whereby the tandem accelerator system 3003 may receive and apply operating parameters from the computing device 3002.

[0088] Any of the control aspects described herein can be controlled or regulated, managed, and / or monitored using system 3000 (e.g., computing device 3002, control system 3001A or 3003A). Examples of these control aspects include bias or voltage applied to any electrode of ion source 22, bias or voltage applied to Einzel lens 30, bias or voltage applied to preaccelerator tube 26, bias or voltage applied to solenoid 510, bias or voltage applied to tandem accelerator 40, voltages output by any of power supplies PS1-PS5, sequences of bias or voltages applied to components of the system for modulation, startup, or breakdown recovery, adjusting beam position for alignment, adjusting beam focus position, adjusting the amount of backflow defocus, and others.

[0089] The communications network 3004 may include any wired or wireless communications network, including, for example, a wired or wireless local area network (LAN), a personal area network (PAN), a metropolitan area network (MAN), a wide area network (WAN), or the like, as well as any hardware, software, and / or firmware required to implement the same (e.g., network routers, etc.). For example, the communications network 3004 may include 802.11, 802.16, 802.20, and / or WiMax networks. Additionally, the communications network 3004 may include a public network, such as the Internet, a private network, such as an intranet, or a combination thereof, and may utilize a variety of currently available or later developed networking protocols, including, but not limited to, TCP / IP-based networking protocols.

[0090] The computing device 3002 and the control systems 3001A and 3003A may be embodied by one or more computing systems, such as the apparatus 3100 shown in FIG. 11. As illustrated in FIG. 11, the apparatus 3100 may include a processor 3102, a memory 3104, input and / or output circuitry 3106, and a communication device or circuitry 3108. These components 3102-3108 may include similar hardware. For example, two components may both utilize the use of the same processor, network interface, storage medium, or the like to perform their associated functions, such that duplicate hardware is not required for each device.

[0091] The terms "device" and / or "circuitry" should be understood broadly to include hardware alone or a combination of hardware and software (e.g., software for configuring the hardware or for performing functions using the hardware). For example, in some embodiments, the device and / or circuitry may include processing circuitry, storage media, network interfaces, input / output devices, and the like. In some embodiments, other elements of the apparatus 3100 may provide or complement the functionality of a particular device. For example, the processor 3102 may provide processing functionality, the memory 3104 may provide storage functionality, the communication device or circuitry 3108 may provide network interface functionality, etc.

[0092] In some embodiments, the processor 3102 (and / or a co-processor or any other processing circuitry that assists or is otherwise associated with the processor) may communicate with the memory 3104 via a bus to pass information between components of the device. The memory 3104 may be non-transitory and may include, for example, one or more volatile and / or non-volatile memories. In other words, for example, the memory 3104 may be an electronic storage device (e.g., a computer-readable storage medium). The memory 3104 may be configured to store information, data, content, applications, instructions, or the like to enable the device to perform various functions according to exemplary embodiments of the present disclosure.

[0093] The processor 3102 may be embodied in a number of different ways, and may, for example, include one or more processing devices configured to perform independently. Additionally or alternatively, the processor may include one or more processors configured to interface via a bus and enable independent execution of instructions, pipelines, and / or multi-threading. Use of the terms "processing device" and / or "processing circuitry" may be understood to include a single-core processor, a multi-core processor, multiple processors, and / or a remote or "cloud" processor internal to an apparatus.

[0094] In an exemplary embodiment, the processor 3102 may be configured to execute instructions stored in the memory 3104 or otherwise accessible to the processor. Alternatively, or in addition, the processor 3104 may be configured to execute hard-coded functionality. Thus, whether configured by hardware or software methods, or by a combination of hardware and software, the processor 3104 may represent an entity (e.g., physically embodied in circuitry) that, while appropriately configured, is capable of performing operations according to certain embodiments of the present disclosure. Alternatively, as another example, when the processor is embodied as an executor of software instructions, the instructions, when executed, may specifically configure the processor to perform the algorithms and / or operations described herein.

[0095] In some embodiments, the apparatus 3100 may include input / output devices 3106, which in turn may communicate with the processor 3102 and provide output to a user and, in some embodiments, may receive input from a user. The input / output devices 3106 may include a device display, such as a user device display, which may include a user interface and may include a web user interface, a mobile application, a client device, or the like. In some embodiments, the input / output devices 3106 may also include a keyboard, a mouse, a joystick, a touch screen, a touch area, soft keys, a microphone, a speaker, or other input / output mechanisms. The processor and / or user interface circuitry including the processor may be configured to control one or more functions of one or more user interface elements through computer program instructions (e.g., software and / or firmware) stored on a memory (e.g., memory 3104 and / or the like) accessible to the processor.

[0096] The communications device or circuitry 3108 may be any device or circuitry, embodied in either hardware or a combination of hardware and software, configured to receive and / or transmit data from and / or to a network and / or any other device or circuitry in communication with the apparatus 3100. In this regard, the communications device or circuitry 3108 may include, for example, a network interface for enabling communication with a wired or wireless communication network. For example, the communications device or circuitry 3108 may include one or more network interface cards, antennas, buses, switches, routers, modems, and supporting hardware and / or software, or any other devices suitable for enabling communication over a network. Additionally or alternatively, the communications interface may include circuitry for interacting with an antenna and causing transmission of signals via the antenna or handling reception of signals received via the antenna. These signals may be transmitted by device 3100 using any of a number of wireless personal area network (PAN) technologies, such as current and future Bluetooth® standards (including Bluetooth® and Bluetooth® Low Energy (BLE)), infrared radio (e.g., IrDA), FREC, ultra-wideband (UWB), inductive radio transmission, or the like. In addition, it should be appreciated that these signals may be transmitted using Wi-Fi, Near Field Communication (NFC), Worldwide Interoperability for Microwave Access (WiMAX), or other proximity-based communication protocols.

[0097] The embodiments of the device that acts on or manipulates digital information may be constructed entirely as hardware or any combination of software and hardware. Furthermore, the embodiments may take the form of a computer program product on at least one non-transitory computer-readable storage medium having computer-readable program instructions (e.g., computer software) embodied in the storage medium. Any suitable computer-readable storage medium may be utilized, including non-transitory hard disks, CD-ROMs, flash memory, optical storage devices, or magnetic storage devices. Processing circuitry for use with the embodiments of the present disclosure may execute software instructions stored on memory that cause the processing circuitry to perform different sets of actions and control other components in the figures herein.

[0098] Memory for use with embodiments of the present disclosure can be shared by one or more of the various functional units, or distributed among two or more of them (e.g., as separate memories residing in different chips). The memory can also be its own separate chip. The memory can be non-transient and further include volatile (e.g., RAM, etc.) and / or non-volatile memory (e.g., ROM, Flash memory, F-RAM, etc.).

[0099] Any such computer program instructions and / or other types of code may be loaded onto a computer, processor, or other programmable device circuitry and run on the machine to produce a machine such that the computer, processor, or other programmable circuitry generates structures for implementing various functions, including those described herein. Computer program instructions for performing operations in accordance with the described subject matter may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Javascript, Smalltalk, C++, C#, Transact-SQL, XML, PHP, or the like, and conventional procedural programming languages ​​such as the "C" programming language or similar programming languages.

[0100] Various aspects of the subject matter are described below as a review of and / or complement to the previously described embodiments, with the interrelationships and interchangeability of the following embodiments being emphasized here. In other words, emphasis is placed on the fact that each feature of the embodiments can be combined with any other feature, unless expressly stated otherwise or logically possible.

[0101] In many embodiments, the beam system includes a particle source configured to emit a charged particle beam, a preaccelerator system configured to accelerate the charged particle beam from the particle source, and an accelerator configured to accelerate the charged particle beam from the preaccelerator system. In some of these embodiments, the particle source is an ion source and the charged particle beam is an ion beam comprising negative hydrogen ions. In some of these embodiments, the preaccelerator system includes at least one of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. In some of these embodiments, the preaccelerator system includes an electrostatic lens, a preaccelerator device, and a magnetic focusing device.

[0102] In some of these embodiments, the electrostatic lens is an Einzel lens, the preaccelerator device is a preaccelerator tube including a plurality of accelerating terminals, and the magnetic focusing device is a solenoid. In some of these embodiments, the electrostatic lens is downstream of the particle source, the preaccelerator device is downstream of the electrostatic lens, and the magnetic focusing device is downstream of the preaccelerator device. In some of these embodiments, the electrostatic lens is an Einzel lens and includes two grounded electrodes coupled in a spaced apart relationship to one another and a bias electrode positioned between the two grounded electrodes and supported by an insulator extending therebetween. In some of these embodiments, the bias electrode or one or more of the two grounded electrodes are configured for negative bias.

[0103] In some of these embodiments, the preaccelerator tube includes a first preaccelerator tube terminal and a second preaccelerator tube terminal. In some of these embodiments, the first preaccelerator tube terminal can be electrically coupled to a first power supply. In some of these embodiments, the second preaccelerator tube terminal can be electrically coupled to ground.

[0104] In some of these embodiments, the accelerator is a tandem accelerator and includes a plurality of input electrodes, a charge exchange device, and a plurality of output electrodes. In some of these embodiments, the charged particle beam is a negative ion beam. In some of these embodiments, the plurality of input electrodes is configured to accelerate a negative ion beam from a preaccelerator system, the charge exchange device is configured to convert the negative ion beam to a positive beam, and the plurality of output electrodes is configured to accelerate the positive beam.

[0105] In some of these embodiments, the beam system further includes a target device configured to form a neutral beam from the positive beam received from the tandem accelerator.

[0106] In some of these embodiments, the preaccelerator system is positioned adjacent to and downstream from the particle source.

[0107] In some of these embodiments, the preaccelerator device is positioned downstream of the electrostatic lens. In some of these embodiments, the magnetic focusing device is positioned downstream of the preaccelerator device. In some of these embodiments, the preaccelerator device is positioned downstream of one or more of the electrostatic lens or the particle source. In some of these embodiments, the magnetic focusing device is positioned downstream of one or more of the Einzel lens, the preaccelerator tube, or the particle source.

[0108] In some of these embodiments, the beam system further includes one or more vacuum pump chambers. In some of these embodiments, a first vacuum pump chamber is positioned between the preaccelerator system and the accelerator. In some of these embodiments, a second vacuum pump chamber is positioned between the particle source and the preaccelerator system.

[0109] In some of these embodiments, one or more vacuum pump chambers are located on the accelerator.

[0110] In some of these embodiments, the particle source includes a wall having one or more filaments located adjacent thereto. In some of these embodiments, the beam system includes a first cooling device configured to cool the wall. In some of these embodiments, the beam system includes a second cooling device configured to cool the Einzel lens. In some of these embodiments, the first and second cooling devices are configured to use a fluid coolant.

[0111] In some of these embodiments, the preaccelerator system is configured to focus a charged particle beam propagating from a particle source at an input aperture of the accelerator.

[0112] In some of these embodiments, the preaccelerator system is configured to defocus and collect the ionized backflow propagating from the accelerator towards the particle source.

[0113] In some of these embodiments, the preaccelerator system is configured to transition a particle beam from a particle source from a divergent state to a convergent state.

[0114] In some of these embodiments, the preaccelerator system includes an electrostatic lens configured to transition the particle beam from the particle source from a divergent state to a focused state, In some of these embodiments, the electrostatic lens is controllable to adjust the beam focusing or countercurrent defocusing.

[0115] In some of these embodiments, the preaccelerator system includes a magnetic focusing device that is controllable to adjust the beam focusing or countercurrent defocusing.

[0116] In some of these embodiments, the preaccelerator system includes a preaccelerator tube that is controllable to adjust the beam focusing or countercurrent defocusing.

[0117] In some of these embodiments, the beam system includes multiple power supplies configured to adjustably output variable power to the magnetic focusing devices, the electrostatic lenses, and the preaccelerator tubes.

[0118] In some of these embodiments, the beam system is configured to accelerate the charged particles to their maximum cross-section prior to entry into the accelerator. In some of these embodiments, the charged particles are negative hydrogen ions. In some of these embodiments, the beam system is configured to accelerate the charged particles to an energy of 100 keV prior to entry into the accelerator. In some of these embodiments, the beam system is configured to accelerate the charged particles to their maximum cross-section at a location within a preaccelerator tube of the preaccelerator system. In some of these embodiments, the location is within a central region of the preaccelerator tube.

[0119] In some of these embodiments, the beam system includes a vacuum pump chamber configured to remove gas exiting the accelerator into the preaccelerator system.

[0120] In some of these embodiments, the particle source is positioned such that the charged particle beam is emitted along the same or a substantially similar axis transverse to the accelerator along which the charged particles passing through the accelerator are accelerated.

[0121] In some of these embodiments, the beam system includes a control system. In some of these embodiments, the control system is configured to receive operational parameters or instructions from a computing device. In some of these embodiments, the control system is configured to transmit operational data to the computing device. In some of these embodiments, the control system is configured to control at least one of the following: a voltage applied to an electrode of the particle source, a voltage applied to an electrostatic lens of the preaccelerator system, a voltage applied to a preaccelerator device of the preaccelerator system, a voltage applied to a magnetic focusing device of the preaccelerator system, a voltage applied to the accelerator, a voltage output by a power supply of the beam system, adjusting a beam position for alignment, adjusting a beam focus position, or adjusting an amount of backflow defocus.

[0122] In some of these embodiments, the beam system is configured for use in boron neutron capture therapy (BNCT).

[0123] In many embodiments, a method of operating a beam system includes emitting a beam comprising charged particles from a particle source, accelerating the beam towards an accelerator using a preaccelerator system, and accelerating the beam using the accelerator.

[0124] In some of these embodiments, the preaccelerator system includes one or more of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. In some of these embodiments, the electrostatic lens is an Einzel lens, the preaccelerator device is a preaccelerator tube including multiple accelerating terminals, and the magnetic focusing device is a solenoid.

[0125] In some of these embodiments, the accelerator is a tandem accelerator. In some of these embodiments, the tandem accelerator includes a charge exchange device. In some of these embodiments, accelerating the beam toward the accelerator with a preaccelerator system includes accelerating the beam such that the charged particles reach their maximum cross-section prior to entering the accelerator. In some of these embodiments, the charged particles are negative hydrogen ions. In some of these embodiments, the charged particles reach their maximum cross-section in a preaccelerator tube of the preaccelerator system.

[0126] In some of these embodiments, the method includes focusing the beam using a preaccelerator system.

[0127] In some of these embodiments, the method includes adjusting power supplied to the preaccelerator system to control focusing of the beam. In some of these embodiments, focusing the beam further includes transitioning the beam from a divergent state to a focused state using the preaccelerator system. In some of these embodiments, the beam is focused using one or more of an electrostatic lens, a preaccelerator device, or a magnetic focusing device. In some of these embodiments, the preaccelerator system includes an electrostatic lens, a preaccelerator device, and a magnetic focusing device. In some of these embodiments, the electrostatic lens is downstream of the particle source, the preaccelerator device is downstream of the electrostatic lens, and the magnetic focusing device is downstream of the preaccelerator device.

[0128] In some of these embodiments, the method includes adjusting the power supplied to the preaccelerator device to control focusing of the beam.

[0129] In some of these embodiments, the method includes adjusting the power supplied to a magnetic focusing device to control the focus of the beam.

[0130] In some of these embodiments, the method includes adjusting power supplied to a preaccelerator device to control focusing of the beam and adjusting power supplied to a magnetic focusing device to control the focus of the beam. In some of these embodiments, adjusting power supplied to a magnetic focusing device to control the focus of the beam includes adjusting power supplied to a magnetic focusing device to focus the beam at an input aperture of the accelerator.

[0131] In some of these embodiments, the particle source is positioned such that the beam is emitted along the same or a substantially similar axis transverse to the accelerator along which the charged particles passing through the accelerator are accelerated.

[0132] In some of these embodiments, the particle source is one of a volume-type source and a surface-type source.

[0133] In some of these embodiments, the method includes defocusing the backflow from the accelerator using a preaccelerator system. In some of these embodiments, the backflow includes ionized background gas. In some of these embodiments, the method includes adjusting power supplied to the preaccelerator system to control the defocusing of the backflow. In some of these embodiments, the method includes adjusting power supplied to the preaccelerator system to cause the backflow to be collected by one or more components of the beam system. In some of these embodiments, the method includes adjusting power supplied to the preaccelerator system to cause the backflow to avoid a backflow-sensitive component of the particle source. In some of these embodiments, the backflow-sensitive component is a filament.

[0134] In some of these embodiments, the counterflow is defocused using one or more of an electrostatic lens, a preaccelerator device, or a magnetic focusing device.

[0135] In some of these embodiments, the preaccelerator system includes an electrostatic lens, a preaccelerator device, and a magnetic focusing device. In some of these embodiments, the electrostatic lens is downstream of the particle source, the preaccelerator device is downstream of the electrostatic lens, and the magnetic focusing device is downstream of the preaccelerator device, relative to beam travel. In some of these embodiments, the method includes adjusting power supplied to the preaccelerator device to control the defocusing of the counterflow. In some of these embodiments, the method includes adjusting power supplied to the magnetic focusing device to control the defocusing of the counterflow. In some of these embodiments, the method includes adjusting power supplied to the preaccelerator device to control the defocusing of the counterflow and adjusting power supplied to the magnetic focusing device to control the defocusing of the counterflow.

[0136] In some of these embodiments, the particle source is positioned such that the beam is emitted along the same or a substantially similar axis transverse to the accelerator along which the charged particles passing through the accelerator are accelerated.

[0137] In some of these embodiments, the method includes performing a vacuum removal of gas. In some of these embodiments, the method includes performing a vacuum removal of gas at a first location between the preaccelerator system and the accelerator and at a second location between the particle source and the preaccelerator system. In some of these embodiments, accelerating the beam toward the accelerator with the preaccelerator system includes accelerating the beam such that the charged particles reach their maximum cross section prior to entering the accelerator.

[0138] In some of these embodiments, the method includes using a control system of the beam system to control at least one of the following: a voltage applied to an electrode of the particle source, a voltage applied to an electrostatic lens of the preaccelerator system, a voltage applied to a preaccelerator device of the preaccelerator system, a voltage applied to a magnetic focusing device of the preaccelerator system, a voltage applied to the accelerator, a voltage output by a power supply of the beam system, adjusting the beam position for alignment, adjusting the beam focus position, or adjusting the amount of backflow defocus.

[0139] In some of these embodiments, the method includes one or more of receiving operational parameters or instructions from a computing device using the control system, or transmitting operational data to a computing device using the control system, In some of these embodiments, the control system is configured for one or more of wireless or wired communication.

[0140] In some of these embodiments, the method includes applying the beam to a target. In some of these embodiments, the particle source is an ion source and the charged particles are negative hydrogen ions. In some of these embodiments, the method includes converting the beam from a negative hydrogen ion beam to a proton beam in an accelerator. In some of these embodiments, applying the beam to the target includes applying a proton beam to a neutron generating target.

[0141] In some of these embodiments, the method includes using the beam system in boron neutron capture therapy (BNCT).

[0142] In many embodiments, a method for defocusing counterflow in a beam system includes evacuating gaseous neutrons from a tandem accelerator and biasing a preaccelerator system coupled to the tandem accelerator. In some of these embodiments, the preaccelerator system is configured to defocus positive ionized gas accelerated by a magnetic field in a direction opposite to the accelerated beam of the beam system. In some of these embodiments, the preaccelerator system includes one or more of a preaccelerator tube, an Einzel lens, a magnetic focusing device, or a solenoid.

[0143] In some of these embodiments, the method includes electrically coupling the preaccelerator tube to a first power supply at a first preaccelerator tube terminal and to ground at a second preaccelerator tube terminal.

[0144] In some of these embodiments, the preaccelerator system is positioned adjacent and downstream from the ion source.

[0145] In some of these embodiments, the preaccelerator tube is mounted adjacent to and downstream of the Einzel lens.

[0146] In some of these embodiments, the magnetic focusing device is mounted adjacent to and downstream of the preaccelerator tube.

[0147] In some of these embodiments, the preaccelerator tube is positioned downstream of one or more of the Einzel lens or the ion source.

[0148] In some of these embodiments, the Einzel lens is positioned downstream of the ion source.

[0149] In some of these embodiments, the magnetic focusing device is positioned downstream of one or more of the Einzel lens, the preaccelerator tube, or the ion source.

[0150] In some of these embodiments, the first vacuum pump chamber is positioned between the preaccelerator system and the tandem accelerator. In some of these embodiments, the second vacuum pump chamber is positioned between the ion source and the preaccelerator system.

[0151] In some of these embodiments, one or more vacuum pump chambers are located on the upper surface of the tandem accelerator.

[0152] In some of these embodiments, the method includes cooling a backplate of the ion source using a first cooling device. In some of these embodiments, the backplate includes one or more filaments. In some of these embodiments, the method includes cooling an Einzel lens using a second cooling device. In some of these embodiments, one or more of the first cooling device or the second cooling device includes water cooling.

[0153] In some of these embodiments, the method includes using a first power supply to bias the magnetic focusing device and adjust the beam focusing or backflow defocusing properties of the magnetic focusing device.

[0154] In some of these embodiments, the method includes using a second power supply to bias the Einzel lens to adjust the beam focusing or backflow defocusing properties of the Einzel lens.

[0155] In some of these embodiments, the method includes using a third power supply to bias the preaccelerator tube and adjust the beam focusing or backflow defocusing properties of the preaccelerator tube.

[0156] In some of these embodiments, the method includes positioning the ion source so that ions are emitted along the same or a substantially similar axis transverse to the tandem accelerator along which ions passing through the tandem accelerator are accelerated.

[0157] In some of these embodiments, the method includes one or more of the steps of using the control system to receive operational parameters or instructions from the computing device, or using the control system to transmit operational data to the computing device.

[0158] It should be noted that all features, elements, components, functions, and steps described with respect to any embodiment provided herein are intended to be freely combinable and substituted with those from any other embodiment. If a feature, element, component, function, or step is described with respect to only one embodiment, it should be understood that the feature, element, component, function, or step can be used with all other embodiments described herein, unless expressly stated otherwise. This paragraph therefore serves as a premise and description aid for the introduction of claims combining features, elements, components, functions, and steps from different embodiments or substituting features, elements, components, functions, and steps from one embodiment with those from another embodiment, wherever applicable, even if the following description does not expressly state that such combinations or substitutions are possible in a particular case. In particular, it is expressly recognized that it would be unduly burdensome to list all possible combinations and substitutions, given that the permissibility of all such combinations and substitutions would be readily recognized by those skilled in the art.

[0159] To the extent that the embodiments disclosed herein include or operate in association with a memory, storage device, and / or computer-readable medium, the memory, storage device, and / or computer-readable medium are non-transitory. Thus, to the extent that the memory, storage device, and / or computer-readable medium are covered by one or more claims, the memory, storage device, and / or computer-readable medium are only non-transitory.

[0160] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0161] While the embodiments are susceptible to various modifications and alternative forms, specific examples thereof are shown in the drawings and described in detail herein. However, it is to be understood that these embodiments are not limited to the particular forms disclosed, but on the contrary, these embodiments cover all modifications, equivalents, and alternatives falling within the spirit of the present disclosure. Furthermore, any feature, function, step, or element of the embodiments may be recited in or added to the claims with a negative limitation that defines the scope of the invention of the claims by the feature, function, step, or element that does not fall within its scope.

Claims

[Claim 1] The invention described in this specification.

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