Systems, devices, and methods for initiating beam delivery in a beam system

Abstract

Embodiments of systems, apparatuses, and methods relate to initiating beam delivery of an accelerator system. An example method includes ramping up a bias voltage of one or more electrodes of an accelerator system to a first voltage level and extracting a charged particle beam from a beam source such that the beam is delivered through the accelerator system. The beam has a beam current that causes a first transient voltage drop within a threshold. The method can further include increasing the beam current at a rate that causes one or more subsequent transient voltage drops until the accelerator system has reached a nominal condition. Another example method includes biasing one or more electrodes of an accelerator system and selectively extracting a charged particle beam from a beam source according to a duty cycle function such that the charged particle beam is delivered through the accelerator system.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 213,618, filed June 22, 2021, entitled “System, Apparatus, and Method for Modulating Start-up Beam Delivery in a Beam System” and U.S. Provisional Application Serial No. 63 / 065,436, filed August 13, 2020, entitled “System, Apparatus, and Method for Start-up Beam Delivery in a Beam System”, the contents of which are incorporated herein by reference in their entirety for all purposes. Technical Field

[0003] The topics described herein generally relate to systems, apparatuses, and methods for initiating beam delivery in a beam system, as well as systems, apparatuses, and methods for modulating initiating beam delivery in a beam system. Background Technology

[0004] Boron neutron capture therapy (BNCT) is a physical therapy used to treat many types of cancer—including some of the most difficult to treat. BNCT is a technique that selectively targets tumor cells while using boron compounds to protect normal cells. A boron-containing substance is injected into a blood vessel, and the boron accumulates in the tumor cells. The patient then receives neutron radiation therapy (e.g., in the form of a neutron beam). The neutrons react with the boron to kill the tumor cells while reducing damage to normal cells compared to alternative therapies. Long-term clinical studies have demonstrated that neutron beams with an energy spectrum in the 3–30 keV range are more suitable for achieving more effective cancer treatment while reducing the patient's radiation load. This energy spectrum or range is often referred to as hyperthermal energy. Most conventional methods for generating hyperthermal neutrons (e.g., hyperthermal neutron beams) are based on the nuclear reaction of protons (e.g., proton beams) with beryllium or lithium (e.g., beryllium or lithium targets).

[0005] A tandem accelerator is an electrostatic accelerator that uses a single high-voltage terminal to accelerate charged particles in a two-step process. The high voltage generates an electric field that is applied to the incident beam of negatively charged ions, causing it to accelerate toward the center of the accelerator. At this point, the beam is converted into a beam of charged particles (e.g., positive ions) of opposite polarity during charge exchange. Further propagation of the charged particles and their interaction with the opposing electric field again leads to acceleration and energy gain. Thus, an accelerating voltage of only 1.5 MV, within the range achievable with modern electrical insulation technology, can produce a charged particle beam with energies of 3 MeV. This tandem beam acceleration method is advantageous because the ion source of a tandem accelerator can be placed at ground potential, making the ion source easier to control and maintain.

[0006] The proton beam provided by a tandem accelerator for boron neutron capture therapy (BNCT) has a preferred energy level for neutron production or generation in downstream devices (e.g., for efficient neutron production on a lithium (Li) target). For reasonably short treatment times, a specific neutron flux density threshold is required, with a minimum proton beam current occurring at this necessary threshold. The power density associated with such proton beams significantly exceeds the safety limits of the materials used in the components of the neutron beam system.

[0007] The initiation of beam delivery via a tandem accelerator at very high voltage levels (e.g., megavolts) is accompanied by various effects, which, in terms of the equivalent circuit, can be represented as the instantaneous load on the tandem power supply. If the beam current associated with the charged particle beam is too high, for example, if the power supply cannot output the required current amplitude, the load change may not be adequately compensated. In this case, the power supply responsible for maintaining the voltage of the tandem accelerator will reduce the voltage supplied to the accelerator. The reduction in the voltage supplied to the accelerator leads to a decrease in beam energy, which is undesirable and increases the probability of damage to downstream beamline components. Depending on the availability and configuration of the interlocking devices monitoring the beam energy, beam termination is possible. Therefore, the initiation and resumption of beam delivery after beam termination caused by other phenomena within the entire neutron beam system must be handled with care. Complex and inefficient recovery or start-up times can result in undesirable system downtime.

[0008] Furthermore, time-dependent recovery or startup procedures (as opposed to those based on other variables) are problematic because beam optics performance can depend on beam energy. Adding a beam trap to absorb the beam during startup or recovery imposes limitations on beamline size (length), complexity, etc. Additionally, internal beam losses within a tandem accelerator can lead to secondary particle emissions (e.g., X-rays), negatively impacting the tandem accelerator's performance and lifetime.

[0009] For these and other reasons, there is a need for improved, efficient and compact systems, devices and methods to provide safe resumption or startup of bundle delivery operations in bundle systems. Summary of the Invention

[0010] Embodiments of the systems, apparatus, and methods relate to the safe resumption or initiation of beam delivery operations of a beam system. An exemplary method includes increasing the bias voltage of one or more electrodes of an accelerator system to a first voltage level. The method may further include extracting a charged particle beam from a beam source such that the beam is delivered through the accelerator system. The beam may have a beam current at a first beam current level, causing a first transient voltage drop in the accelerator system within a threshold value. The method may further include increasing the beam current at a rate that causes one or more subsequent transient voltage drops in the accelerator system until the accelerator system has reached nominal conditions. The one or more subsequent transient voltage drops may be within a threshold value.

[0011] Embodiments of the systems, apparatus, and methods further relate to the modulation initiation of beam delivery operations of a beam system. An exemplary method includes biasing one or more electrodes of an accelerator system to a given voltage level. This exemplary method further includes selectively extracting a charged particle beam from a beam source according to a duty cycle function, such that the charged particle beam is delivered through the accelerator system. The duty cycle function may be linear or nonlinear and may include a frequency f, which may be fixed (constant) or variable. The duty cycle function may include a variable pulse duration, such that the variable pulse duration increases over time with each selective extraction of the charged particle beam.

[0012] Other systems, apparatuses, methods, features, and advantages of the subject matter described herein will be apparent to or will become apparent to those skilled in the art upon review of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages are included within the scope of this description, the subject matter described herein, and protected by the appended claims. Features of exemplary embodiments should in no way be construed as limiting the appended claims, where no explicit statement of those features is made in the claims. Attached Figure Description

[0013] The details of the subjects described herein, both in terms of their structure and operation, become apparent from the accompanying drawings, in which the same reference numerals denote the same parts. The components in the drawings are not necessarily drawn to scale, but rather emphasize the principles of the illustrated subjects. Furthermore, all illustrations are intended to convey concepts, where relative dimensions, shapes, and other detailed properties may be shown schematically rather than literally or precisely.

[0014] Figure 1A This is a schematic diagram of an example of a neutron beam system.

[0015] Figure 1B This is a schematic diagram of another example of a neutron beam system.

[0016] Figure 2An exemplary pre-accelerator system or ion beam injector for use with embodiments of this disclosure is illustrated.

[0017] Figure 3A yes Figure 2 A perspective view of the ion source and the ion source vacuum chamber shown.

[0018] Figure 3B It is a description Figure 3A An exploded perspective view of an exemplary embodiment of the single lens shown.

[0019] Figure 4A An exemplary ion beam source system for use with embodiments of this disclosure is illustrated.

[0020] Figure 4B The diagram shows... Figure 4A The exemplary ion source depicted in the document.

[0021] Figures 5A-5D An exemplary timing diagram associated with embodiments of the present disclosure is illustrated.

[0022] Figures 6A-6D An exemplary timing diagram associated with embodiments of the present disclosure is illustrated.

[0023] Figure 7 Exemplary operations for initiating beam delivery in a beam system are illustrated for use with embodiments of this disclosure.

[0024] Figures 8A-8B This is a timing diagram depicting an exemplary embodiment of a pulse sequence used for beam extraction.

[0025] Figure 9 This is a graph depicting an exemplary embodiment of the duty cycle function used in conjunction with embodiments of the present disclosure.

[0026] Figure 10 This is a block diagram depicting a system in which embodiments of the present disclosure may operate.

[0027] Figure 11 This is a block diagram depicting an exemplary embodiment of a computing device that can be specifically configured according to embodiments of the present disclosure. Detailed Implementation

[0028] Before describing this subject matter in detail, it will be understood that this disclosure is not limited to the specific embodiments described, as these are of course subject to variation. It will also 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 this disclosure will be limited only by the appended claims.

[0029] The term “particle” is used extensively throughout this document and, unless otherwise limited, can be used to describe electrons, protons (or H+ ions) or neutrons, as well as matter having more than one electron, proton and / or neutron (e.g., other ions, atoms and molecules).

[0030] Exemplary embodiments of systems, apparatuses, and methods are described herein for operational recovery of beam systems (e.g., including particle accelerators). The embodiments described herein can be used with any type of particle accelerator or for any particle accelerator application involving the generation of charged particle beams at specified energies for supply to a particle accelerator. The embodiments described herein can be used in many applications, one example being as a neutron beam system for generating neutron beams for boron neutron capture therapy (BNCT). For ease of description, many embodiments described herein are performed in the context of a neutron beam system for BNCT, although these embodiments are not limited to neutron beam or BNCT applications.

[0031] Voltage performance is a crucial indicator or target for electrostatic particle accelerators. Voltage performance broadly refers to the output voltage capability and stability, as the accelerating voltage of the charged particle beam applied within the particle accelerator is preferably known and controllable. Within the accelerator volume, the stability of the accelerating voltage V (and therefore the beam energy) is typically affected by the power supply output current (charging current) I. CH Charged particle beam current I B and discharge current I dis The limiting effect of fluctuations. Under steady-state conditions, the current balance can be expressed as follows:

[0032]

[0033] Where Z is the total load of the accelerator power supply. dis This includes dark current (e.g., leakage current along insulators), corona discharge, and spark discharge.

[0034] When spark development is accompanied by relatively high discharge current amplitudes, existing voltage regulator circuits cannot handle induced voltage fluctuations well due to power limitations. Depending on the magnitude of the discharge current, the accelerator may experience partial or complete voltage breakdown. The accelerator voltage drop may exceed a threshold beyond which charged particle beam delivery becomes unsafe and is therefore terminated by the control system. Such action prevents damage to beamline components, including those downstream of the accelerator.

[0035] Restarting beam delivery is a critical task for beams with relatively high currents after an accelerator voltage breakdown event. In fact, according to equation (1) above, if the charged particle beam current I... B Exceeding the charging current I CHThe sudden start-up of the beam can lead to an undesirable accelerator voltage drop or breakdown. This, in turn, may terminate the beam again due to safety procedures. Therefore, breakdown recovery is challenging for beams with relatively high currents because steady-state I... B It may exceed I CH And the system may not be able to recover effectively.

[0036] Because the embodiments of this disclosure achieve a gradual change in the current of the negative ion beam extracted from the ion source through fine-tuning of the ion source's operating state, the beam current of the extracted negative ion beam can change smoothly and gradually increase. This smooth change and gradual increase in the extracted beam current enables the safe recovery and startup of beam transport within the neutron beam system.

[0037] The methods for adjusting the ion source, as described in this paper, facilitate the matching of plasma parameters near the ion extraction region, ion source component bias and current, and ion extraction and beam delivery optics to generate an ion beam with a desired current amplitude downstream of the ion source. Adjusting the ion source may include pre-setting the parameters of the involved components or using more complex control logic to accommodate undesired deviations of the beam current from the desired value. For example, in volumetric ion sources, such adjustments can be achieved by controlling the arc discharge current, filament current, plasma and extraction electrode voltages, and the rate at which hydrogen is supplied to the ion source.

[0038] Advantageously, embodiments of this disclosure are able to efficiently and safely restore beam delivery operation within a beam system while preserving beam energy. In some embodiments, only the beam current is adjusted during the proposed beam recovery method.

[0039] While multiple initial states of a neutron beam system may exist prior to performing the operations described herein, examples of initial states of a neutron beam system include: a) no beam is currently being extracted (e.g., standby or pre-start), or b) no voltage is applied to the tandem accelerator (e.g., breakdown, therefore requiring recovery). Although the embodiments described herein may refer to the "recovery" of beam delivery, it should be understood that the operations described herein can be applied to the initiation of beam delivery without departing from the scope of this disclosure.

[0040] Initiating bundle delivery may involve interlocking devices on the accelerator and bundle assembly (e.g., the triggers described above for terminating bundle delivery) to ensure proper and safe bundle delivery. In a steady state of DC bundle generation, these interlocking devices may be configured to react to deviations from a safety corridor value for a specific measurement (e.g., a voltage reading outside a given MV interval, such as 2:2.1) or temperatures exceeding a given threshold (e.g., 40°C). This safety corridor for a specific measurement can be defined as a value that is a function of parameters of the bundle and bundle assembly (e.g., the accelerator). The functional dependence of the safety corridor may be non-linear and can be very complex. Therefore, changing the operating parameters of the bundle may result in adjustments to the interlocking devices to maintain safety standards for the bundle components or other related equipment. This approach leads to complex control systems and requires highly complex implementation, testing, longer commissioning times, and dedicated hardware and diagnostics.

[0041] The embodiments of this disclosure overcome the aforementioned disadvantages and more by initiating DC beam delivery with minimal (or no) modifications to the control and interlocking systems and without additional hardware or diagnostics. This embodiment further reduces the total time required to initiate beam delivery at full performance (e.g., the critical process of beam recovery).

[0042] Embodiments of this disclosure enable beam-loaded accelerators extracted at full current amplitude via a variable duty cycle function. The variable duty cycle function may include a period 1 / f and a pulse duration for beam extraction that varies over time. For example, in embodiments, the duration of a second pulse following a first pulse with a first pulse duration may be increased by up to a specific percentage of the first pulse duration without triggering beam termination or other undesired component states (e.g., accelerator voltage drop exceeding a tolerable voltage drop threshold). That is, in some embodiments, the duration of a subsequent pulse may be increased by up to 10% compared to the previous pulse duration. In various embodiments, the percentage increase in the duration of subsequent pulses may range from 25% or less, 20% or less, 15% or less, or 10% or less. This percentage may depend on the specific requirements of the beam-loading component or application. In some embodiments, the duration of each successive pulse may be increased, while in other embodiments, pulses with increased durations may be repeated successively with that increased duration, and then the pulse duration may increase again. The pulses may be repeated a predetermined number of times, or for a predetermined duration, or until the system has stabilized or recovered sufficiently (e.g., based on voltage sensor feedback). For example, a first set of pulses, each having a first duration, can be repeated for the first time, and then a second set of pulses, each having the same second duration (longer than the first duration), can be repeated for the second time (same or different from the first time), and so on, until the beam is fully recovered. The embodiments described herein enable faster beam recovery because beam delivery can be initiated at any current amplitude (e.g., even at beam currents corresponding to nominal performance).

[0043] Please see the attached image for details. Figure 1A This is a schematic diagram of an exemplary embodiment of a beam system 10 for use with embodiments of the present disclosure. Figure 1A In this system, beam system 10 includes a source 12, a low-energy beamline (LEBL) 14, an accelerator 16 coupled to the LEBL 14, and a high-energy beamline (HEBL) 18 extending from the accelerator 16 to a target 100. The LEBL 14 is configured to deliver a beam from the source 12 to the input of the accelerator 16, which is in turn configured to generate a beam by accelerating the beam delivered by the LEBL 14. The HEBL 18 transfers the beam from the output of the accelerator 16 to the target 100. The target 100 may be a structure configured to produce a desired result in response to a stimulus applied by the incident beam, or may alter the properties of the beam. The target 100 may be a component of system 10 or may be a workpiece at least partially regulated or manufactured by system 10.

[0044] Figure 1BThis is a schematic diagram illustrating another exemplary embodiment of a neutron beam system 10 for boron neutron capture therapy (BNCT). Here, source 12 is an ion source and accelerator 16 is a tandem accelerator. The neutron beam system 10 includes a pre-accelerator system 20 serving as a charged particle beam injector, a high-voltage (HV) tandem accelerator 16 coupled to the pre-accelerator system 20, and an HEBL 18 extending from the tandem accelerator 16 to a neutron target assembly 200 housing a target 100 (not shown). In this embodiment, the target 100 is configured to produce neutrons in response to a bombardment of protons with sufficient energy and may be referred to as a neutron-generating target. The neutron beam system 10 and the pre-accelerator system 20 may also be used in other applications, such as those other examples described herein, and are not limited to BNCT.

[0045] The pre-accelerator system 20 is configured to deliver an ion beam from the ion source 12 to the input (e.g., the input aperture) of the tandem accelerator 16, thus also acting as the LEBL 14. Powered by a high-voltage power supply 42 coupled thereto, the tandem accelerator 16 produces a proton beam with energy typically equal to twice the voltage applied to the accelerating electrodes positioned within the accelerator 16. This proton beam energy level can be achieved by accelerating the innermost high-potential electrodes from the negative hydrogen ion beam at the input of the accelerator 16, stripping two electrons from each ion, and then accelerating the resulting protons downstream with the same applied voltage.

[0046] HEBL 18 delivers a proton beam from the output of accelerator 16 to a target within neutron target assembly 200, which is positioned at the end of a branch 70 of a beamline extending into a patient treatment chamber. System 10 can be configured to guide the proton beam to any number of targets and associated treatment areas within one or more targets. In this embodiment, HEBL 18 includes three branches 70, 80, and 90 that can extend into three different patient treatment chambers, each terminating in the target assembly 200 and a downstream beam shaping device (not shown). HEBL 18 may include a pump chamber 51, quadrupole magnets 52 and 72 to prevent beam defocusing, dipole or bending magnets 56 and 58 to guide the beam into the treatment chamber, a beam corrector 53, diagnostic devices such as current monitors 54 and 76, a fast beam position monitor section 55, and a scanning magnet 74.

[0047] The design of HEBL 18 depends on the construction of the processing facility (e.g., a single-layer construction, a two-layer construction, etc.). A bending magnet 56 can be used to deliver the beam to the target assembly (e.g., positioned near the treatment chamber) 200. A quadrupole magnet 72 can be included to subsequently focus the beam to a specific dimension at the target. The beam is then passed through one or more scanning magnets 74, which causes the beam to move laterally across the target surface in a desired pattern (e.g., spirals, bends, staircases in rows and columns, combinations thereof, etc.). Lateral beam movement helps achieve a smooth and uniform temporal distribution of the proton beam on the lithium target, thereby preventing overheating and ensuring that neutron generation within the lithium layer is as uniform as possible.

[0048] After entering the scanning magnet 74, the beam can be transmitted to a current monitor 76 for measuring the beam current. A gate valve 77 can be used to physically separate the target assembly 200 from the HEBL volume. The primary function of the gate valve is to separate the vacuum volume of the beamline from the target when loading the target and / or replacing a used target with a new one. In this embodiment, the beam cannot be bent 90 degrees by the magnet 56, but rather flows directly towards... Figure 1B The beam travels to the right and then enters a quadrupole magnet 52 located in the horizontal beam. The beam can then be bent to the desired angle by another bending magnet 58, depending on the building and room construction. Alternatively, the bending magnet 58 can be replaced with a Y-shaped magnet to split the beam in two directions for two different treatment rooms located on the same floor.

[0049] Figure 2 An example of a pre-accelerator system or ion beam implanter used with embodiments of this disclosure is shown. In this example, the pre-accelerator system 20 (e.g., LEBL 14) includes a single lens 30 (in... Figure 2 Invisible in the middle, but in Figures 3A-3B The system comprises a pre-accelerator tube 26 and a solenoid 510, and is configured to accelerate a negative ion beam injected from the ion source 12. The pre-accelerator system 20 is configured to provide the energy required to accelerate the beam particles to the tandem accelerator 16 and to provide overall focusing of the negative ion beam to match the inlet aperture or inlet area of ​​the tandem accelerator 16. The pre-accelerator system 20 is also configured to minimize backflow or defocusing backflow when recirculating from the tandem accelerator 16 through the pre-accelerator system, thereby reducing the possibility of damage to the ion source 12 and / or backflow to the filament of the ion source.

[0050] In one embodiment, the ion source 12 may be configured to provide a negative ion beam upstream of the single lens 30, and the negative ion beam continues through the pre-accelerator tube 26 and the magnetic focusing device (e.g., a solenoid) 510. The solenoid 510 may be positioned between the pre-accelerator tube 26 and the tandem accelerator 16 and may be electrically connected to a power source. The negative ion beam reaches the tandem accelerator 16 through the solenoid 510.

[0051] The pre-accelerator system 20 may also include an ion source vacuum chamber 24 for gas removal and a pump chamber 28, the pump chamber 28 being part of a relatively low-energy beamline leading to the tandem accelerator 16, along with the pre-accelerator tube 26 and the other aforementioned components. A single lens 30 may be positioned within the ion source vacuum chamber 24, which extends from the ion source 12. The pre-accelerator tube 26 may be coupled to the ion source vacuum chamber 24 and the solenoid 510. The vacuum pump chamber 28 for gas removal may be coupled to the solenoid 510 and the tandem accelerator 16. The ion source 12 serves as a source of charged particles that, when conveyed to a neutron generator, can be accelerated, tuned, and ultimately used to generate a neutron target. Exemplary embodiments will be described herein with reference to an ion source that generates a negative hydrogen ion beam, but the embodiments are not limited thereto, and the source may generate other positive or negative particles.

[0052] The pre-accelerator system 20 may have zero or one or more magnetic elements for purposes such as focusing and / or adjusting beam alignment. For example, any such magnetic element may be used to match the beam to the beamline axis and the receiving angle of the tandem accelerator 16. The ion vacuum chamber 24 may have ion optics positioned therein.

[0053] Negative ion sources 12 are generally of two types based on their mechanisms of negative ion generation: surface-type and volumetric-type. Surface-type sources typically require the presence of cesium (Cs) on a specific inner surface. Volumetric-type sources rely on the formation of negative ions within a volume of high-current discharge plasma. While both types of ion sources can deliver the required negative ion current for applications associated with tandem accelerators, surface-type negative ion sources are not suitable for modulation. That is, for the modulation of the negative ion beam in the embodiments described herein, a volumetric negative ion source (e.g., without cesium (Cs)) is preferred.

[0054] Turning Figure 3A The ion source vacuum chamber 24 of the ion beam implanter 20 (e.g., or LEBL 14) includes a single lens 30 positioned therein. Figure 3B As shown in detail, the single lens 30 downstream of the grounding lens 25 of the ion source 12, which can be installed within the vacuum chamber 24, includes a mounting plate 32, two grounding electrodes 34 coupled to each other and spaced apart from each other by the mounting plate 32 and the mounting rod 35, and a energized (biased) electrode 38 positioned between the two grounding electrodes 34. The electrodes 34 and 38 are in the form of cylindrical apertures and assembled to have an axial axis coinciding with the beam path. The energized electrode 38 is supported by a spacer (or insulator) 36 extending between the grounding electrodes or the aperture 34.

[0055] The support isolator 36 may have a geometry configured to prevent the development of electron avalanche and suppress the formation and propagation of streamers that could cause flashover. The geometry of the support isolator 36 can partially shield the external electric field on the insulator surface that drives electron avalanche and effectively increase the path length. Additionally, the material of the insulator / isolator 36 tends to reduce sputtering effects, loss of negative ions on the surface, volume contamination, and the formation of conductive coatings on the insulator / isolator surface that reduce electrical strength.

[0056] Functionally, the single lens 30 acts on the beam of charged particles advancing from the ion source 12 in a manner similar to that of an optical focusing lens. That is, the single lens 30 focuses the incident parallel beam onto a point on the focal plane. However, the electric field formed here between the paired energized electrodes 38 and the two grounded electrodes 34 determines the focusing intensity (focal length) of the single lens.

[0057] By mounting the single lens 30 downstream of the ion source grounding lens 25, it reduces beam free space transport, where the beam diverges due to inherent space charge.

[0058] The dimensions of the axisymmetric or approximately axisymmetric design of the single lens 30 are optimized to avoid direct interaction between extracted ions and the exposed surface of the single lens 30.

[0059] In operation, the negative polarity bias of the single lens 30 results in a higher focusing capability than a positive polarity bias. Also in operation, the method of powering the single lens 30 provides a gradual voltage increase rather than an instantaneous voltage application, which reduces the electric field growth rate (dE / dt) present on the surface of the single lens 30 at micro-protrusions that could form plasma via, for example, an explosive emission mechanism. Preventing the formation of such plasma improves electrical strength.

[0060] Due to electrical breakdown, a negative bias potential for a single lens under high background pressure is typically impossible. The exemplary configuration of the single lens provided herein enables the application of a sufficiently high negative bias voltage to achieve 100% current utilization without electrical breakdown.

[0061] Figure 4A An exemplary ion beam source system for use with embodiments of this disclosure is shown. Figure 4A Optionally, the ion source 12 is housed within an ion source enclosure. The ion source 12 includes multiple electrodes, such as a plasma electrode 320, a grounding lens 310, and an extraction electrode 330. Optionally, the ion source 12 is coupled to a single lens 30, and a negative ion beam is injected or propagated from the ion source 12 through the single lens 30, the pre-accelerator tube 26, and the solenoid 510 to the input aperture of the tandem accelerator 16.

[0062] Reference Figure 4BIon source 12 can be electrically coupled to the first (grounded) terminal of power supply PS3 at ground lens 310, and power supply PS3 is in turn electrically coupled to ion source 12 at a second terminal. The bias of ion source 12 relative to ground lens 310 allows for the extraction and transmission of a high-current negative ion beam downstream of the ion source. In some embodiments, power supply PS3 can provide a voltage of -30 kV. Divergence of the high-current negative ion beam due to space charge is further suppressed by accelerating the ion beam in pre-accelerator tube 26, while solenoid 510 is used to precisely match the injected ion beam to the input aperture of tandem accelerator 16.

[0063] The plasma electrode 320 of the ion source 12 is electrically coupled to the power supply PS5, and the extraction electrode 330 of the ion source 12 is electrically coupled to the modulator 350, which in turn is electrically coupled to the power supply PS4. The biasing of the plasma electrode 320 enables the ion source 12 to maintain the desired electron energy distribution, thereby facilitating the more efficient extraction of negative ions from the plasma boundary within the ion source 12 using the extraction electrode 330.

[0064] When the extraction electrode 330 is biased, the negative ion beam is extracted from the ion source 12 and accelerated by the grounded lens 310 toward the injector component downstream of the ion source 12. When the extraction electrode 330 is not biased, the negative ion beam is not extracted.

[0065] As described above, the tandem accelerator 16 is powered by a high-voltage power supply PS6 coupled thereto and can produce a proton beam with energy substantially equal to twice the voltage applied to the accelerating electrodes positioned within the tandem accelerator 16. The power supply PS6 can be controlled by a feedback loop to maintain voltage stability within the tandem accelerator 16. That is, a measuring or control device 360 ​​(e.g., a voltmeter) can monitor the voltage across the plurality of tandem electrodes (G) of the tandem accelerator 16.

[0066] The power supply (e.g., PS6) powering accelerator 16 may have physical and design-related limitations on its output voltage and current. The control circuitry (e.g., measurement or control device 360) may also have limited bandwidth in signal acquisition and processing and may be characterized as a proportional-integral-derivative (PID) loop for output voltage stabilization. These and other factors associated with the power supply (e.g., PS6) can cause a significant increase in the response time of the power supply (e.g., PS6) for accelerator 16 under triggered events. Therefore, accelerator 16 can easily be loaded with beam pulses of duration less than (or approximately) 1 millisecond (ms) and frequency of 10 Hz (e.g., 1% duty cycle), while the beam current can be as large as 10 mA. In contrast, initiating a 10 mA beam delivery results in an accelerator voltage drop of nearly 50% and triggers beam termination.

[0067] The embodiments described herein address physical and design-related limitations associated with the power supply (e.g., PS6) powering the accelerator 16 and the control circuitry monitoring the power supply and parameters of the accelerator 16 by driving the load of the accelerator 16 with a beam current that varies with time at full performance. The full performance of the accelerator may be determined by application-specific requirements (e.g., for patient treatment). In some embodiments, the beam current is 15 mA at 2.7 MeV.

[0068] Figures 5A-5C It is a graph depicting an exemplary embodiment of the operation of the beam system 10. Figure 5A It is a graph showing the relationship between voltage and time for the accelerator power supply (used to power the electrodes). Figure 5B This is a graph showing the beam current in LEBL 190 before it is input to accelerator 40. Figure 5C This is a graph showing the setpoint of the current in beam source 22. Before time t0, accelerator 40 operates normally for medical purposes, where the accelerator voltage is at the normal voltage V. N The beam current stabilizes at the nominal beam current level I. LD An event occurs at time t0 that causes a drop in accelerator voltage. This could be an intentional shutdown of system 10, a breakdown event (e.g., an arc from within accelerator 40 when using extremely high voltage), etc. In response to the detection of this event, the control system 3001A (Figure 8) of system 10 terminates beam extraction and the current drops to zero. Figure 5B ).

[0069] The control system 3001A also, for example, issues a command to the beam source 22 at t0 to change the setpoint of the beam source from I. LN Change or adjust to a lower current level I suitable for starting or restarting the beam. LI The speed at which beam source 22 adjusts to the new setpoint depends on the design and implementation of the beam source, and this will vary depending on the embodiment. In this embodiment, the dynamics of beam source 22 require time to modify to the new setpoint, and beam source 22 reaches the new setpoint at or before time t2. Adjusting beam source 22 can increase the accelerator voltage to V. N It occurred before, during (at the same time as), or after.

[0070] The process of adjusting the beam source 22 may include tasks such as matching plasma parameters, such as plasma density, near the beam or ion extraction region of the source 22, so that the plasma is sufficient to reliably extract the ion beam at the requested current. Adjustment may further include tasks such as matching the parameters of the extracted ion beam (e.g., energy, alignment, focal length) with downstream beam delivery optics to minimize losses. Adjustment can be performed by regulating controllable settings of the ion source components. For example, adjustment may include controlling or regulating the arc discharge current of the source, regulating the filament current of the source, regulating the plasma electrode voltage, regulating the extraction electrode voltage, and / or regulating the rate at which hydrogen is supplied to the source 22.

[0071] After determining to restart system 10, control system 3001A applies a bias voltage to the electrodes of accelerator 40 at time tR, and the accelerator voltage is directed towards V. N The beam rises, reaching that level at time t1. At time t2, the control system 3001A allows the beam extraction to proceed at I. LI Starting at the set point (e.g., through the extraction electrode of bias source 22), and the beam current rises to I... LI The beam propagates directly through accelerator 40, causing a beam with amplitude V. D The transient accelerator voltage drop is 501. LI and V D There is a direct relationship between the amplitudes of I and I. LI The higher the level, the more V D The higher.

[0072] Changes in accelerator voltage translate into changes in beam energy, which in turn translates into deviations from the optimal axis. While beam optics are present within system 10 to readjust the beam upon deviation, these optics typically have very little time to detect and respond to such deviations. At relatively high beam currents, even brief deviations can damage beam system components. Therefore, I LO It is preferable to maintain a relatively low level to avoid damage when the beam deviates.

[0073] In these exemplary embodiments, I can be selected LI The amplitude is to ensure the transient voltage drop V D (And therefore the degree of deflection) remains at the threshold V. T Inside. In other words, I LI The magnitude of this voltage drop can cause the accelerator voltage to fall above the minimum permissible voltage (V). M The above levels are to avoid specific I LI Damaged system 10 at horizontal level. For selected I LIThe threshold corresponds to the maximum permissible deflection time of the beam from its axis. This takes into account the time required for beam optics (e.g., magnetic elements) to detect and compensate for beam axis deflection, as well as the magnitude of the beam current (a weaker beam can deviate from the axis for a relatively long time before causing damage). This threshold can correspond to the adjustment response time of various components of the beam system. Depending on the beamline parameters downstream of the tandem accelerator, some small variations in beam energy may be insufficient to cause beamline damage due to the small deviation of the beam from the axis, or they can be compensated for using active ion optics based on feedback signals.

[0074] At time t3, the accelerator voltage has returned to the nominal level V. N Furthermore, the control system 3001A issues a signal to adjust the beam source 22 to the nominal beam current level I. LN ( Figure 5C The command is given. In this embodiment, the beam source 22 gradually increases the beam current to I from time t3 to t4. LN To respond. This gradual increase corresponds to maintaining a threshold V. T Another transient voltage drop 502 occurs within the system. In some embodiments, multiple sequential commands can be issued to adjust the setpoint at progressively increasing levels, causing source 22 to increase gradually or in a step function manner. At time t4, both the accelerator voltage and beam current have returned to the nominal levels for treatment, and system 10 has fully recovered or started up. In some embodiments, system 10 can increase the beam current from zero to I at a controlled and relatively slow rate. LN This keeps the transient voltage drop at V T Inside.

[0075] Figure 5D Another exemplary embodiment of the accelerator voltage is depicted, wherein the start-up ratio of the ramp-up process tR' is... Figure 5A In this embodiment, tR' occurs early. Here, tR' occurs while the voltage drop from the initial event at t0 is still ongoing and has not yet reached zero. Therefore, the accelerator voltage is ramped up to V. N The time is reduced, and System 10 can be faster than... Figure 5A The system returns to the nominal condition much faster at t4. In other words, a change in tR can correspond to a much larger change at t4, so the system 10 can return to the nominal treatment condition much faster.

[0076] Figures 6A-6D It describes representative features for bundle delivery recovery and / or startup. Figures 5A-5D A graph of data from an exemplary embodiment of the present disclosure is provided for use in conjunction with embodiments thereof. Figure 6A The voltage on the electrodes of the accelerator, which is powered by a power source, is depicted. Figure 6B The charging current (I) of the accelerator power supply is described.CH ), Figure 6C The negative ion beam current in LEBL 190 before being input to accelerator 40 is depicted. Figure 6D The proton beam current in HEBL 50 after output from accelerator 40 is depicted. Times t2, t3, and t4 are shown. Figures 6A-6D The text is marked and corresponds to the reference. Figures 5A-5C Those moments described.

[0077] Here, before time t2, the accelerator voltage is at the nominal level V. N And the beam is turned off. Before time t2, beam source 22 is adjusted to I. LI In this embodiment, it is approximately one milliampere (mA). At time t2, the beam in I... LI The voltage is extracted and accelerator 40 experiences a transient voltage drop of 501, and the supply current rises to a value greater than I. LI The approximation is a steady-state level of 2mA (I SS (A brief dip occurred before this.) At time t3, the accelerator had reached V. N Furthermore, the setpoint of beam source 22 was modified to I. LN At this point, the beam current gradually increases until it reaches I. LN It is approximately 10mA. Figure 6C Simultaneously, the accelerator voltage experiences a second instantaneous drop of 502. Neither drops of 501 nor 502 will cause the accelerator voltage to drop to V. M Below. After acceleration and conversion into a proton beam, the beam current becomes approximately 7 mA ( Figure 6D ).

[0078] Figure 7 This is a flowchart depicting an exemplary embodiment of a method 700 for initiating beam delivery in a beam system. In 701, the bias voltage of one or more electrodes of the accelerator system is increased to a first voltage level (e.g., nominal voltage V). N In 702, at the first beam current level (e.g., I). LI The accelerator extracts (or otherwise propagates) a beam of charged particles from a beam source. The initial beam current level causes the first transient voltage drop (V) in the accelerator system. D ), where the first transient voltage drop is at the threshold (V T Within ) . The accelerator voltage will not drop to the minimum permissible voltage (V) of the first beam current level. M Below 703, the beam current increases at a rate that causes one or more subsequent transient voltage drops in the accelerator system until the accelerator system reaches a second beam current level (e.g., I0). LN One or more subsequent transient voltage drops are within the threshold.

[0079] exist Figure 6A In an exemplary embodiment, for a beam current of approximately 1 mA, the threshold (V) N –V M The threshold is approximately 70 kV. This threshold can and will vary based on the amplitude of the beam current, the resilience of the system 10 to beam impacts when deviating from the axis, the rate at which beam deviation can be detected, and the rate at which deviation can be corrected.

[0080] I LI The amplitude can be lower than I LN and steady-state charging current I to meet specific application requirements SS Any current value. For example, in Figure 6C In the embodiments, I LI It is one milliampere (mA), I SS It is two milliamps, and I LN It is approximately ten milliamps, but both values ​​can vary. In some embodiments, I LI The amplitude in I SS The value is between 0.01% and 75%.

[0081] Figure 8A and 8B This is a graph depicting an exemplary embodiment of a pulse sequence for beam extraction within an exemplary beam system 10. Exemplary beam operation includes extracting a beam according to a beam extraction trigger sequence and a given duty cycle function. The beam extraction trigger sequence may include a first command issued by a control system (e.g., 3001A) to change the setpoint of the beam source to a desired current level such that source 12 is ready to output a beam with a desired current amplitude. The control system (e.g., 3001A) may then cause (e.g., by issuing a second command) a bias voltage to be applied to the electrodes of accelerator 16, and the accelerator voltage is directed towards V. N (For example, the nominal voltage or desired operating voltage of the accelerator) is increased. The control system 3001A can then cause (for example, by issuing a third command) beam extraction to begin (for example, by biasing the extraction electrode of the bias source 12). Figure 8A and 8B This involves bundle extraction triggering, and bundle extraction triggering may include the command sequence described above to initiate and / or trigger bundle extraction according to embodiments herein.

[0082] The beam extraction trigger sequence may follow a given duty cycle function. The duty cycle function may include a period 1 / f (e.g., the beam or pulse to which it is extracted), a pulse duration that increases over time (e.g., the duration of the beam extraction pulse), or both. That is, the control system (e.g., 3001A, Figures 8A-8B (Not shown) can be configured (e.g., programmed) to issue one or more commands that cause the bundle to be extracted at a specific time. Figure 8AIn an exemplary embodiment, a first pulse 501 is extracted at time 0. For example, as a result of one or more commands issued by the control system 3001A, beam extraction may continue for the duration of the first pulse before beam extraction is interrupted or stopped. The control system 3001A may then issue one or more commands to cause beam extraction at time 1 / f for a second pulse duration longer than the duration of the first pulse. The second pulse duration may end due to the control system 3001A issuing one or more commands to interrupt beam extraction. The control system 3001A may then issue one or more commands to cause beam extraction at time 2 / f for a third pulse duration longer than both the second and first pulse durations. The third pulse duration may end due to the control system 3001A issuing one or more commands to interrupt beam extraction. The control system 3001A may then issue one or more commands to cause beam extraction at time 3 / f for a fourth pulse duration longer than each of the third, second, and first pulse durations. The fourth pulse duration may end due to the control system 3001A issuing one or more commands to interrupt beam extraction. The control system 3001A can then issue one or more commands to induce beam extraction at time 4 / f for a fifth pulse duration longer than each of the fourth, third, second, and first pulse durations. Exemplary operation can continue until the Nth extraction signal is initiated to form a DC beam 510, where N is a number and can be set according to a particular embodiment (e.g., N could be 5, 50, 500, 5000, etc.).

[0083] Figure 8A An embodiment in which the pulse duration increases with each successive pulse is depicted. Other embodiments may vary. Figure 8BAn exemplary embodiment is depicted, in which pulses are repeated for a specific duration before the next increase. Here, a first group of 551 pulses 501-1 to 501-3 are extracted, each pulse having the same duration. Then a second group of 552 pulses 501-4 to 501-6 are extracted, each pulse again having the same duration, but longer than the pulse duration of the first group of 551 pulses. Then a third group of 553 pulses 501-7 to 501-9 with even longer durations are extracted, followed by a fourth group of 554 pulses 501-10 to 501-12 with even longer durations. The process can continue with multiple groups of successively increasing pulse durations until DC beam formation occurs. In this embodiment, each group comprises three pulses; however, these groups may have other pulse counts that are the same as or different from each other. The duration of a group can be predetermined (e.g., pre-programmed) based on pulse counts (e.g., a group continues until a predetermined pulse count is reached) or elapsed time (e.g., a group continues until a predetermined time has elapsed). A set of parameters can be dynamically terminated based on feedback from the system; for example, a set can continue until the accelerator voltage level has stabilized based on sensed feedback to the control system. In other embodiments, the system can be used to monitor system stability while simultaneously monitoring system stability. Figure 8A Similar to other embodiments, it uses successive increasing duration pulses to begin beam extraction, and can transition to a state similar to [other methods] when a load or instability is sensed (e.g., voltage below a minimum threshold). Figure 8B Similar embodiments exist, in which the same pulses are repeated until the load is relieved or the instability is resolved (or until a predetermined time or count is reached), after which the system can switch back to pulses with successively increasing durations. Figure 8A In some embodiments, when a load or instability is sensed, the system may revert to a shorter pulse duration until the pulse duration can be increased.

[0084] Figure 9 This is a graph depicting an exemplary duty cycle function used in conjunction with embodiments of this disclosure. For example, in Figure 9 In, the duty cycle used for beam operations (e.g., such as...) Figures 8A-8B (as shown) may include linear or nonlinear functions. In Figure 9 In the diagram, the first function x610 (e.g., represented by a dashed line) can be a linear function from which the duty cycle can be calculated or generated. Alternative functions or a second function... (For example, represented by a solid line) can be a nonlinear function from which the duty cycle can be calculated or generated. It should be understood that the duty cycle can be selected or adjusted based on the power supply of accelerator 16 (e.g., PS6). Examples of criteria used to determine the duty cycle function may include the accelerator power supply's ability to maintain the output voltage within a specific range (e.g., a safe or safe corridor). In the example, slowing the rate of change of the duty cycle when the accelerator power supply begins to detect an increase in load caused by the pulse beam may be preferred.

[0085] Figure 10 This is a block diagram illustrating an exemplary system in which embodiments of the present disclosure may operate. For example, the illustrated exemplary system includes a beam system 10 and one or more computing devices 3002. In embodiments, the beam system 10 may be part of an exemplary neutron beam system (e.g., system 10 above). In such embodiments, the beam system 10 may employ one or more control systems 3001A with which one or more computing devices 3002 can communicate to interact with the system and components of the beam system 10 (e.g., neutron beam system 10). Each of these devices and / or systems is configured to communicate directly with each other or via a local network (e.g., network 3004).

[0086] The computing device 3002 may be embodied in various user devices, systems, computing devices, etc. For example, a first computing device 3002 may be a desktop computer associated with a specific user, another computing device 3002 may be a laptop computer associated with a specific user, and yet another computing device 3002 may be a mobile device (e.g., a tablet or smart device). Each of the computing devices 3002 may be configured to communicate with the beam system 10, for example, through a user interface accessible via the computing device. For example, a user may execute a desktop application on the computing device 3002, which is configured to communicate with the beam system 3001.

[0087] By communicating with the beam system 3001 using the computing device 3002, a user can provide operating parameters (e.g., operating voltage, etc.) for component 3005 here, according to the embodiments described herein. In an embodiment, the beam system 10 may include a control system 3001A, through which the beam system 10 receives and applies operating parameters from the computing device 3002.

[0088] The control system 3001A can be configured to receive measurements, signals, or other data from components 3005 and monitoring devices 3003 of the bundle system 10. For example, the control system 3001A can receive signals from one or more monitoring devices 3003 indicating operating conditions and / or the position of the bundles through the bundle system 3001. Depending on the operating conditions and / or the position of the bundles through the bundle system, the control system 3001A can provide adjustments to the inputs of one or more bundle components 3005 according to the methods described herein. The control system 3001A can also provide information collected from any component of the bundle system 10 (including monitoring devices 3003) directly or via a communication network 3004 to a computing device 3002.

[0089] The communication network 3004 may include any wired or wireless communication network, such as a wired or wireless local area network (LAN), personal area network (PAN), metropolitan area network (MAN), wide area network (WAN), etc., and any hardware, software, and / or firmware required to implement it (e.g., network routers, etc.). For example, the communication network 3004 may include 802.11, 802.16, 802.20, and / or WiMax networks. Furthermore, the communication network 3004 may include public networks such as the Internet, private networks such as intranets, or combinations thereof, and may utilize various networking protocols now available or developed in the future, including but not limited to TCP / IP based on networking protocols.

[0090] The computing device 3002 and the control system 3001A may be embodied by one or more computing systems, such as Figure 11 The device shown is 3100. (As shown) Figure 11 As shown, device 3100 may include processor 3102, memory 3104, input and / or output circuitry 3106, and communication means or circuitry 3108. It should also be understood that some of these components 3102-3108 may include similar hardware. For example, both components may leverage the same processor, network interface, storage medium, etc., to perform their associated functions, thus avoiding the need for duplicate hardware for each device. Therefore, the use of the terms "means" and / or "circuitry" as used herein with respect to components of a device may encompass specific hardware configured with software to perform functions associated with that particular device, as described herein.

[0091] The terms "device" and / or "circuit" should be broadly understood to include hardware, and in some embodiments, the device and / or circuit may also include software for configuring the hardware. For example, in some embodiments, the device and / or circuit may include processing circuitry, storage media, network interfaces, input / output devices, etc. In some embodiments, other elements of the device 3100 may provide or supplement 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 circuit 3108 may provide network interface functionality, and so on.

[0092] In some embodiments, processor 3102 (and / or coprocessor or auxiliary processor or any other processing circuitry otherwise associated with the processor) may communicate with memory 3104 via a bus to transfer information between components of the device. 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, memory may be an electronic storage device (e.g., a computer-readable storage medium). Memory 3104 may be configured to store information, data, content, applications, instructions, etc., 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 variety of different ways and may, for example, include one or more processing devices configured to operate independently. Additionally or alternatively, the processor may include one or more processors configured in series via a bus to enable independent execution of instructions, pipelining, and / or multithreading. The use of the terms "processing device" and / or "processing circuitry" is to be understood to include single-core processors, multi-core processors, multiple processors within a device, and / or remote or "cloud" processors.

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

[0095] In some embodiments, device 3100 may include an input / output device 3106, which may communicate with processor 3102 to provide output to a user and, in some embodiments, receive input from the user. Input / output device 3106 may include a user interface and may include a device display, such as a user device display that may include a web user interface, mobile application, client device, etc. In some embodiments, input / output device 3106 may also include a keyboard, mouse, joystick, touchscreen, touch area, softkeys, microphone, speaker, or other input / output mechanism. 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 via computer program instructions (e.g., software and / or firmware) stored in processor-accessible memory (e.g., memory 3104, etc.).

[0096] The communication device or circuit 3108 can be any device, such as device circuitry embodied in hardware or a combination of hardware and software, configured to receive and / or transmit data from / to a network and / or any other device or circuitry communicating with device 3100. In this regard, the communication device or circuit 3108 may include, for example, a network interface for enabling communication with wired or wireless communication networks. For example, the communication device or circuit 3108 may include one or more network interface cards, antennas, buses, switches, routers, modems, and supporting hardware and / or software, or any other means suitable for enabling communication via a network. Additionally or alternatively, the communication interface may include circuitry for interacting with an antenna to induce the transmission of signals via the antenna or for processing signals received via the antenna. These signals may be transmitted by device 3100 using any of a variety of wireless personal area network (PAN) technologies, such as current and future Bluetooth standards (including Bluetooth and Bluetooth Low Energy (BLE)), infrared wireless (e.g., IrDA), FREC, ultra-wideband (UWB), inductive wireless generation, etc. Additionally, it should be understood that these signals can be transmitted using Wi-Fi, Near Field Communication (NFC), Global Microwave Access Interoperability (WiMAX), or other short-range-based communication protocols.

[0097] It should be understood that any such computer program instructions and / or other type of code can be loaded onto the circuitry of a computer, processor, or other programmable device to produce a machine, such that the computer, processor, or other programmable circuitry executing the code on the machine creates means to implement a variety of functions—including those described herein.

[0098] As will be understood from the above and based on this disclosure, embodiments of this disclosure can be configured as systems, methods, mobile devices, backend network devices, etc. Therefore, embodiments can include various means, including entirely hardware or any combination of software and hardware. Furthermore, embodiments can 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 can be used, including non-transitory hard disks, CD-ROMs, flash memory, optical storage devices, or magnetic storage devices.

[0099] Processing circuitry used in conjunction with embodiments of the present disclosure may include one or more processors, microprocessors, controllers, and / or microcontrollers, each of which may be discrete chips or distributed across multiple different chips (and portions thereof). Processing circuitry used in conjunction with embodiments of the present disclosure may include a digital signal processor, which may be implemented in the hardware and / or software of the processing circuitry used in conjunction with embodiments of the present disclosure. Processing circuitry used in conjunction with embodiments of the present disclosure may be communicatively coupled to other components of the accompanying drawings. Processing circuitry used in conjunction with embodiments of the present disclosure may execute software instructions stored in memory that cause the processing circuitry to take a variety of different actions and control other components of the accompanying drawings.

[0100] Memory used in conjunction with embodiments of this disclosure may be shared by one or more of various functional units, or may be distributed among two or more of them (e.g., as separate memory located within different chips). The memory itself may also be a separate chip. The memory may be non-transitory and may be volatile memory (e.g., RAM, etc.) and / or non-volatile memory (e.g., ROM, flash memory, F-RAM, etc.).

[0101] Computer program instructions that perform operations according to the described subject can 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, etc., as well as traditional procedural programming languages ​​such as the "C" programming language or similar programming languages.

[0102] The following review and / or supplementation of the embodiments described to date illustrates various aspects of this subject matter, with emphasis placed on the interrelationships and interchangeability of the following embodiments. In other words, emphasis is placed on the fact that each feature of the embodiments can be combined with every other feature, unless expressly stated otherwise or logically implausible.

[0103] In some embodiments, a method of initiating beam delivery of a tandem accelerator system includes biasing one or more electrodes of the tandem accelerator system to a first voltage level. In some of these embodiments, the method further includes extracting a charged particle beam from a beam source such that the charged particle beam is delivered through the tandem accelerator system. In some of these embodiments, the charged particle beam has a beam current at a first beam current level that causes a first transient voltage drop in the tandem accelerator system within a threshold value. In some of these embodiments, the method further includes increasing the beam current at a rate that causes one or more subsequent transient voltage drops in the tandem accelerator system until the beam current reaches a second beam current level. In some of these embodiments, the one or more subsequent transient voltage drops are within the threshold value.

[0104] In some of these embodiments, the threshold corresponds to a beam deflection time that is less than the maximum beam deflection time, which causes the charged particle beam to deviate from the beam axis.

[0105] In some of these embodiments, the threshold corresponds to the adjustment response time of the beam optics of the beam system in which the tandem accelerator system is located.

[0106] In some embodiments of these examples, the method further includes adjusting the beam source to provide the charged particle beam having a beam current at the first beam current level. In some embodiments of these examples, the beam source is adjusted before extracting the charged particle beam. In some embodiments of these examples, extracting the charged particle beam includes biasing the extraction electrodes when it is determined that the beam source has been adjusted.

[0107] In some of these embodiments, adjusting the beam source includes sending a command to the beam source to operate at a first beam current level. In some of these embodiments, the beam source adjustment is performed before biasing one or more electrodes of the tandem accelerator system to the first voltage level.

[0108] In some of these embodiments, increasing the beam current includes sending a command to the beam source to operate at a second beam current level.

[0109] In some of these embodiments, the beam source is an ion source. In some of these embodiments, adjusting the ion source includes matching one or more of the plasma parameters near the ion extraction region such that the plasma is sufficiently favorable for reliably extracting the ion beam with the requested current.

[0110] In some of these embodiments, the ion source includes a volumetric ion source. In some of these embodiments, adjusting the ion source includes controlling one or more of the following: arc discharge current, filament current, plasma electrode voltage, extraction electrode voltage, or the rate at which hydrogen is supplied to the ion source.

[0111] In some of these embodiments, the extraction of the charged particle beam is performed after one or more electrodes of the tandem accelerator system have reached the first voltage level. In some of these embodiments, the beam source is configured to supply a charged particle beam to the tandem accelerator system, which is located downstream of the beam source.

[0112] In some of these embodiments, the beam source is configured to generate a negative hydrogen ion beam.

[0113] In some of these embodiments, the beam source includes a non-cesium ion source.

[0114] In some of these embodiments, the tandem accelerator system includes a first set of electrodes, a charge exchange device, and a second set of electrodes. In some of these embodiments, biasing one or more electrodes of the tandem accelerator system to the first voltage level includes biasing the first set of electrodes and the second set of electrodes.

[0115] In some of these embodiments, the charged particle beam is a negative ion beam, the first set of electrodes is configured to accelerate the negative ion beam from the pre-accelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the second set of electrodes is configured to accelerate the positive beam.

[0116] In some of these embodiments, the method further includes forming a neutral beam from the positive beam using a target device.

[0117] In some of these embodiments, the method further includes using the pre-accelerator system to accelerate the charged particle beam as it propagates from the beam source through the pre-accelerator system to the tandem accelerator system.

[0118] In some of these embodiments, the method further includes reducing the bias of one or more electrodes of the tandem accelerator system due to a breakdown event at the tandem accelerator system before biasing the one or more electrodes of the tandem accelerator system to the first voltage level. In some of these embodiments, the method further includes determining to restart the tandem accelerator system before biasing the one or more electrodes of the tandem accelerator system to the first voltage level.

[0119] In some of these embodiments, the first beam current level is in the range of 0.01% to 75% of the steady-state charging current of the tandem accelerator system.

[0120] In some of these embodiments, the second beam current level is a nominal therapeutic level.

[0121] In some of these embodiments, the charged particle beam is a negative ion beam.

[0122] In some embodiments, a beam system includes a beam source, a tandem accelerator system including one or more electrodes configured to be biased to a first voltage level, and a control system. In some of these embodiments, the control system is configured to control the beam source to generate a charged particle beam having a beam current at a first beam current level corresponding to a first transient voltage drop of the tandem accelerator system within a threshold value. In some of these embodiments, the control system is further configured to control the beam source to increase the beam current at a rate that causes one or more subsequent transient voltage drops in the tandem accelerator system until the beam current reaches a second beam current level. In some of these embodiments, the one or more subsequent transient voltage drops are within the threshold value.

[0123] In some of these embodiments, the threshold corresponds to a beam deflection time that is less than the maximum beam deflection time, which causes the charged particle beam to deviate from the beam axis.

[0124] In some of these embodiments, the threshold corresponds to the adjustment response time of the beam optics of the beam system.

[0125] In some of these embodiments, the control system is further configured to adjust the beam source to the first beam current level and cause the charged particle beam to be extracted from the beam source with a beam current at the first beam current level.

[0126] In some of these embodiments, the control system is further configured to adjust the beam source to the second beam current level while causing the charged particle beam to be extracted from the beam source.

[0127] In some of these embodiments, the beam source includes an extraction electrode.

[0128] In some of these embodiments, the beam source is a volumetric ion source, and the control system is configured to control one or more of the following: arc discharge current, filament current, plasma electrode voltage, extraction electrode voltage, or the rate at which hydrogen is supplied to the beam source.

[0129] In some of these embodiments, the control system is further configured to control the bias of one or more electrodes of the tandem accelerator system.

[0130] In some of these embodiments, the control system is further configured to cause: (a) the bias on one or more electrodes of the tandem accelerator system to be increased to the first voltage level and (b) the beam source to be adjusted to the first beam current level simultaneously with (a).

[0131] In some of these embodiments, the control system is further configured to cause: (a) the bias on one or more electrodes of the tandem accelerator system to increase to the first voltage level and (b) the beam source to be adjusted to the first beam current level after the bias on one or more electrodes reaches the first voltage level.

[0132] In some of these embodiments, the control system is further configured to cause: (a) the beam source to be adjusted to the first beam current level and (b) the bias on one or more electrodes of the tandem accelerator system to be increased to the first voltage level after the beam source is adjusted to the first beam current level.

[0133] In some of these embodiments, the beam source includes a non-cesium ion source.

[0134] In some of these embodiments, the tandem accelerator system includes a first set of electrodes, a charge exchange device, and a second set of electrodes.

[0135] In some of these embodiments, the charged particle beam is a negative ion beam, the first set of electrodes is configured to accelerate the charged particle beam from the pre-accelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the second set of electrodes is configured to accelerate the positive beam.

[0136] 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 system.

[0137] In some of these embodiments, the beam system further includes a pre-accelerator system configured to accelerate the charged particle beam as it propagates from the beam source into the tandem accelerator system.

[0138] In some of these embodiments, the control system is further configured to cause the bias applied to one or more electrodes of the tandem accelerator system to decrease due to a breakdown event at the tandem accelerator system before the bias of one or more electrodes of the tandem accelerator system increases to the first voltage level.

[0139] In some of these embodiments, the control system is further configured to determine to restart the tandem accelerator system before the bias of the one or more electrodes of the tandem accelerator system increases to the first voltage level.

[0140] In some of these embodiments, the first beam current level is in the range of 0.01% to 75% of the steady-state charging current of the tandem accelerator system.

[0141] In some of these embodiments, the second beam current level is a nominal therapeutic level. In some of these embodiments, the charged particle beam is a negative ion beam.

[0142] In many embodiments, a method for modulating beam delivery for a beam system includes biasing one or more electrodes of the accelerator system to a voltage level, and selectively extracting charged particle beam pulses from a beam source such that the charged particle beam pulses are transmitted through the accelerator system and their duration increases over time.

[0143] In some of these embodiments, charged particle beam pulses are extracted based on a linear and / or nonlinear duty cycle function. In some of these embodiments, the duty cycle function may be adjusted in response to a detected increase in load caused by the charged particle beam. In some of these embodiments, the charged particle beam pulses are extracted at a frequency f, which may be a fixed or variable frequency. In some of these embodiments, the duty cycle function corresponds to successive charged particle beam pulses with increasing pulse duration. In some of these embodiments, the duration of each successive extracted charged particle beam pulse is longer than the immediately preceding charged particle beam pulse.

[0144] In some of these embodiments, a first charged particle beam pulse is extracted at a first time 1 / f with a first pulse duration, and a second charged particle beam pulse is extracted at a second time 2 / f with a second pulse duration. In some of these embodiments, the second pulse duration is greater than the first pulse duration.

[0145] In some embodiments of these examples, a first set of charged particle beam pulses is extracted, followed by the extraction of a second set of charged particle beam pulses. In some embodiments of these examples, each pulse in the first set has a first duration, and each pulse in the second set has a second duration longer than the first duration. In some embodiments of these examples, the second set of charged particle beam pulses begins after a predetermined number of charged particle beam pulses in the first set have been extracted. In some embodiments of these examples, the second set of charged particle beam pulses begins after a predetermined time has elapsed since the extraction of the first set of charged particle beam pulses.

[0146] In some embodiments of these examples, the method further includes sensing a load or instability while extracting the first set of charged particle pulses, and extracting a second set of charged particle pulses after the sensed load or instability has been resolved. In some embodiments of these examples, the load or instability is a voltage drop.

[0147] In some of these embodiments, selective extraction of the charged particle beam includes a bias extraction electrode.

[0148] In some of these embodiments, the accelerator system is a tandem accelerator system. In some of these embodiments, selective extraction of the charged particle beam is performed after one or more electrodes of the tandem accelerator system have reached the voltage level.

[0149] In some of these embodiments, the beam source is configured to provide a beam of charged particles to the accelerator system, which is located downstream of the beam source.

[0150] In some of these embodiments, the beam source is configured to generate a negative hydrogen ion beam.

[0151] In some of these embodiments, the beam source includes a non-cesium ion source.

[0152] In some of these embodiments, the accelerator system is a tandem accelerator system comprising a first set of multiple electrodes, a charge exchange device, and a second set of multiple electrodes. In some of these embodiments, biasing one or more electrodes of the tandem accelerator system to the voltage level includes biasing the first set of multiple electrodes and the second set of multiple electrodes. In some of these embodiments, the charged particle beam is a negative ion beam. In some of these embodiments, the first set of multiple electrodes is configured to accelerate the negative ion beam from a pre-accelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the second set of multiple electrodes is configured to accelerate the positive beam. In some of these embodiments, the method further includes forming a neutral beam from the positive beam using a target device.

[0153] In some of these embodiments, the method further includes using the pre-accelerator system to accelerate the charged particle beam as it propagates from the beam source through the pre-accelerator system to the accelerator system.

[0154] In some of these embodiments, the method further includes extracting a continuous beam of charged particles.

[0155] In some embodiments, a beam system includes a beam source, an accelerator system, and a control system configured to control the beam source such that charged particle beam pulses of increasing duration are selectively extracted from the beam source and delivered through the accelerator system. In some of these embodiments, the control system is configured to control the beam source to extract charged particle beam pulses according to a linear and / or nonlinear duty cycle function. In some of these embodiments, the control system is further configured to detect an increase in load caused by the charged particle beam and adjust the duty cycle function in response to the detected increase in load.

[0156] In some of these embodiments, the control system is configured to control the beam source such that the charged particle beam pulses are selectively extracted at a frequency f, which may be a fixed or constant frequency. In some of these embodiments, the duty cycle function is configured to cause the extraction of charged particle beam pulses with successively increasing pulse durations. In some of these embodiments, the control system is configured to control the beam source to cause a first set of charged particle beam pulses to be extracted, followed by a second set of charged particle beam pulses. In some of these embodiments, each pulse in the first set has a first duration, and each pulse in the second set has a second duration longer than the first duration.

[0157] In some embodiments of these examples, the control system is configured to control the beam source to extract a second set of charged particle beam pulses after a predetermined number of charged particle beam pulses in the first set have been extracted. In some embodiments of these examples, the control system is configured to control the beam source to begin extracting the second set of charged particle beam pulses after a predetermined time period has elapsed since the first set of charged particle beam pulses were extracted. In some embodiments of these examples, the control system is configured to sense load changes or instability and cause the beam source to continue extracting charged particle pulses for the same duration until the sensed load change or instability is resolved.

[0158] In some of these embodiments, the accelerator system is a tandem accelerator system that includes one or more electrodes configured to be biased to a first voltage level.

[0159] In some of these embodiments, the control system is further configured to control the application of a bias to the extraction electrode to induce selective extraction of the charged particle beam.

[0160] In some of these embodiments, the beam source includes an extraction electrode.

[0161] In some of these embodiments, the control system is configured to control the application of bias to one or more electrodes of the accelerator system.

[0162] In some of these embodiments, the accelerator system is a tandem accelerator system including a first set of multiple electrodes, a charge exchange device, and a second set of multiple electrodes. In some of these embodiments, the charged particle beam is a negative ion beam. In some of these embodiments, the first set of multiple electrodes is configured to accelerate the charged particle beam from a pre-accelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the second set of multiple electrodes is configured to accelerate the positive beam.

[0163] In some of these embodiments, the beam system further includes a target device configured to form a neutral beam from a positive beam received from the tandem accelerator system.

[0164] In some of these embodiments, the beam system further includes a pre-accelerator system configured to accelerate the charged particle beam pulse from the beam source to the accelerator system.

[0165] In some of these embodiments, the charged particle beam pulse is a negative ion beam pulse.

[0166] It should be noted that all features, elements, components, functions, and steps described with respect to any embodiments provided herein are intended to be freely combined and substituted with features, elements, components, functions, and steps 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 such feature, element, component, function, or step may be used with every other embodiment described herein, unless expressly stated otherwise. Therefore, this paragraph serves at all times as the basis for reference and written support of the introduction of the claims, which combine features, elements, components, functions, and steps from different embodiments, or substitute features, elements, components, functions, and steps from one embodiment for features, elements, components, functions, and steps from another embodiment, even if such combinations or substitutions are not expressly stated in particular cases. It is expressly acknowledged that a detailed description of every possible combination and substitution would be overly cumbersome, especially considering that the permissibility of each such combination and substitution will be readily apparent to those skilled in the art.

[0167] In the sense that the embodiments disclosed herein include a memory, storage device, and / or computer-readable medium, or operate in conjunction with them, the memory, storage device, and / or computer-readable medium is non-transitory. Therefore, in the sense that the memory, storage device, and / or computer-readable medium is covered by one or more claims, the memory, storage device, and / or computer-readable medium is merely non-transitory.

[0168] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly specifies otherwise.

[0169] While the embodiments are readily available with various modifications and alternatives, specific examples have been shown in the accompanying drawings and described in detail herein. However, it should be understood that these embodiments are not limited to the specific forms disclosed, but rather, they will cover all modifications, equivalents, and alternatives falling within the spirit of this disclosure. Furthermore, any feature, function, step, or element of the embodiments may be recited in or added to the claims, as well as to the claims or such negative limitations that define the scope of the invention by features, functions, steps, or elements not within the scope of the claims.

Claims

1. A method for initiating beam delivery in a tandem accelerator system, the method comprising: One or more electrodes of the tandem accelerator system are biased to a first voltage level; A charged particle beam is extracted from a beam source, such that the charged particle beam is conveyed through the tandem accelerator system, wherein the charged particle beam has a beam current at a first beam current level, which causes a first transient voltage drop in the tandem accelerator system within a threshold value, the threshold value corresponding to the adjustment response time of the beam optics of the beam system located in the tandem accelerator system; and The beam current is increased at a rate that causes one or more subsequent transient voltage drops in the tandem accelerator system until the beam current reaches a second beam current level, wherein the one or more subsequent transient voltage drops are within the threshold.

2. The method according to claim 1, wherein, The threshold corresponds to the beam deflection time of the charged particle beam that is less than the maximum beam deflection time.

3. The method of claim 1, further comprising adjusting the beam source to provide a beam of charged particles having a beam current at the first beam current level.

4. The method according to claim 3, wherein, The beam source is adjusted before extracting the charged particle beam.

5. The method according to claim 3, wherein, Extracting the charged particle beam includes biasing the extraction electrode when it is determined that the beam source has been adjusted.

6. The method according to claim 3, wherein, Adjusting the beam source includes sending a command to the beam source to operate at a first beam current level.

7. The method according to claim 6, wherein, The beam source is adjusted before one or more electrodes of the tandem accelerator system are biased to a first voltage level.

8. The method according to claim 1, wherein, Increasing the beam current includes sending a command to the beam source to operate at a second beam current level.

9. The method according to claim 3, wherein, The beam source is an ion source, and the ion source is adjusted by matching plasma parameters near the ion extraction region of the ion source, such that the plasma is sufficient to extract an ion beam at the requested current.

10. The method according to claim 9, wherein, The ion source includes a volumetric ion source, and adjusting the ion source includes controlling one or more of the following: arc discharge current, filament current, plasma electrode voltage, extraction electrode voltage, or the rate at which hydrogen is supplied to the ion source.

11. The method according to claim 1, wherein, The extraction of the charged particle beam is performed after one or more electrodes of the tandem accelerator system have reached the first voltage level.

12. The method according to claim 1, wherein, The beam source is configured to provide a beam of charged particles to the tandem accelerator system, which is located downstream of the beam source.

13. The method according to claim 1, wherein, The beam source is configured to generate a negative hydrogen ion beam.

14. The method according to claim 1, wherein, The beam source includes a non-cesium ion source.

15. The method according to claim 1, wherein, The tandem accelerator system includes a first plurality of electrodes, a charge exchange device, and a second plurality of electrodes.

16. The method according to claim 15, wherein, Biasing one or more electrodes of a tandem accelerator system to the first voltage level includes biasing the first plurality of electrodes and the second plurality of electrodes.

17. The method according to claim 15, wherein, The charged particle beam is a negative ion beam, wherein the first plurality of electrodes are configured to accelerate the negative ion beam from the pre-accelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the second plurality of electrodes are configured to accelerate the positive beam.

18. The method of claim 17, further comprising forming a neutral beam from the positive beam using a target device.

19. The method of claim 1, further comprising: As the charged particle beam propagates from the beam source through the pre-accelerator system to the tandem accelerator system, the pre-accelerator system is used to accelerate the charged particle beam.

20. The method of claim 1, further comprising: Before biasing one or more electrodes of the tandem accelerator system to the first voltage level, the bias of one or more electrodes of the tandem accelerator system is reduced due to a breakdown event at the tandem accelerator system.

21. The method of claim 20, further comprising: Before biasing one or more electrodes of the tandem accelerator system to the first voltage level, it is determined that the tandem accelerator system should be restarted.

22. The method according to any one of claims 1-21, wherein, The first beam current level is in the range of 0.01% to 75% of the steady-state charging current of the tandem accelerator system.

23. The method according to any one of claims 1-22, wherein, The second beam current level is the nominal therapeutic level.

24. The method according to any one of claims 1-16 or 19-23, wherein, The charged particle beam is a negative ion beam.

25. A beam system, comprising: Source of the bundle; A tandem accelerator system comprising one or more electrodes configured to be biased to a first voltage level; and The control system is configured as follows: The beam source is controlled to generate a charged particle beam having a beam current at a first beam current level, the first beam current level corresponding to a first transient voltage drop of the tandem accelerator system within a threshold, the threshold corresponding to the adjustment response time of the beam optics of the beam system; and The beam source is controlled to increase the beam current at a rate that causes one or more subsequent transient voltage drops in the tandem accelerator system until the beam current reaches a second beam current level, wherein the one or more subsequent transient voltage drops are within the threshold.

26. The beam system according to claim 25, wherein, The threshold corresponds to the beam deflection time of the charged particle beam that is less than the maximum beam deflection time.

27. The beam system according to claim 25, wherein, The control system is configured to: Adjust the beam source to the first beam current level; and This causes the charged particle beam to be extracted from the beam source with a beam current at the level of the first beam current.

28. The beam system according to claim 25, wherein, The control system is configured to: The beam source is adjusted to the second beam current level, thereby causing the charged particle beam to be extracted from the beam source.

29. The beam system according to claim 25, wherein, The beam source includes an extraction electrode.

30. The beam system according to claim 25, wherein, The beam source is a volumetric ion source, and the control system is configured to control one or more of the following: arc discharge current, filament current, plasma electrode voltage, extraction electrode voltage, or the rate at which hydrogen is supplied to the beam source.

31. The beam system according to claim 25, wherein, The control system is further configured to control the bias of one or more electrodes of the tandem accelerator system.

32. The beam system according to claim 31, wherein, The control system is configured to cause: (a) the bias on one or more electrodes of the tandem accelerator system to be increased to the first voltage level, and (b) the beam source to be adjusted to the first beam current level simultaneously with (a).

33. The beam system according to claim 31, wherein, The control system is configured to cause: (a) the bias on one or more electrodes of the tandem accelerator system to increase to the first voltage level and (b) the beam source to be adjusted to the first beam current level after the bias on one or more electrodes reaches the first voltage level.

34. The beam system according to claim 31, wherein, The control system is configured to cause: (a) the beam source to be adjusted to the first beam current level, and (b) the bias on one or more electrodes of the tandem accelerator system to be increased to the first voltage level after the beam source is adjusted to the first beam current level.

35. The beam system according to claim 25, wherein, The beam source includes a non-cesium ion source.

36. The beam system according to claim 25, wherein, The tandem accelerator system includes a first plurality of electrodes, a charge exchange device, and a second plurality of electrodes.

37. The beam system according to claim 36, wherein, The charged particle beam is a negative ion beam, wherein the first plurality of electrodes are configured to accelerate the charged particle beam from the pre-accelerator system, the charge exchange device is configured to convert the negative ion beam into a positive beam, and the second plurality of electrodes are configured to accelerate the positive beam.

38. The beam system of claim 37, further comprising a target device configured to form a neutral beam from the positive beam received from the tandem accelerator system.

39. The beam system of claim 25, further comprising: A pre-accelerator system configured to accelerate the charged particle beam as it propagates from the beam source into the tandem accelerator system.

40. The beam system according to claim 25, wherein, The control system is configured to cause the bias applied to one or more electrodes of the tandem accelerator system to decrease due to a breakdown event at the tandem accelerator system before the bias of one or more electrodes of the tandem accelerator system increases to the first voltage level.

41. The beam system according to claim 40, wherein, The control system is configured to determine to restart the tandem accelerator system before the bias of one or more electrodes of the tandem accelerator system increases to the first voltage level.

42. The beam system according to any one of claims 25-41, wherein, The first beam current level is in the range of 0.01% to 75% of the steady-state charging current of the tandem accelerator system.

43. The beam system according to any one of claims 25-42, wherein, The second beam current level is the nominal therapeutic level.

44. The beam system according to any one of claims 25-36 and 40-43, wherein, The charged particle beam is a negative ion beam.

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