A mixed four-beam type ion accelerator

Abstract

The application relates to the technical field of synchrotron, in particular to a mixed four-beam type ion accelerator which comprises an ion source, a radio frequency quadrupole field accelerator, a focusing device and a target chamber arranged in sequence, wherein the ion source is used for continuously generating N ion beams with different mass-to-charge ratios; the radio frequency quadrupole field accelerator is provided with N beam channels and is used for simultaneously accelerating the N ion beams with different mass-to-charge ratios; the focusing and bunching device is provided with a conical solenoid and is used for converging the N ion beams with different mass-to-charge ratios after acceleration into one beam to form a mixed ion beam with different mass-to-charge ratios; and the target chamber is used for placing target materials and injecting the mixed ion beam. The ion source of the ion accelerator can generate ion beams with different mass-to-charge ratios and simultaneously make the ion beams with different mass-to-charge ratios achieve different acceleration effects to obtain beam flows with different energies, and then the beam flows are converged and injected into the target chamber, so that the flexibility is higher.

Description

Technical Field

[0001] This application relates to the field of synchrotron technology, and more specifically to a hybrid four-beam ion accelerator. Background Technology

[0002] Ion implantation is a method for doping semiconductors and surface treatment of metals. Impurities are ionized into ions and focused into an ion beam. After being accelerated in an electric field to obtain extremely high kinetic energy, the beam is implanted into the material to achieve doping.

[0003] Existing ion accelerators mostly use tandem and electrostatic acceleration methods, and are composed of multiple accelerators and ion sources. Their beam intensity is relatively low, and there are certain limitations in the selection of ion types. Summary of the Invention

[0004] To address the aforementioned technical issues, this application provides a hybrid four-beam ion accelerator that can inject ions with different mass-to-charge ratios, offering high flexibility.

[0005] The technical solution provided in this application is as follows:

[0006] A hybrid four-beam ion accelerator includes an ion source, a radio frequency quadrupole accelerator, a focusing device, and a target chamber arranged sequentially, wherein:

[0007] An ion source is used to continuously generate N different mass-to-charge ratio ion beams.

[0008] The radio frequency quadrupole accelerator has N beam channels to simultaneously accelerate N ion beams with different mass-to-charge ratios.

[0009] The focusing device is equipped with a conical solenoid to converge N accelerated ion beams with different mass-to-charge ratios into a single beam, forming a mixed ion beam with different mass-to-charge ratios.

[0010] The terminal target chamber is used to place the target material and inject the mixed ion beam.

[0011] In one optional embodiment, the radio frequency quadrupole accelerator includes an acceleration cavity, M stem-ring electrodes, and N rod electrode groups. Each rod electrode group has four rod electrodes, which are arranged to form a beam channel. The M stem-ring electrodes are evenly distributed along the beam channel, and each stem-ring electrode is connected to the acceleration cavity. N ports are symmetrically opened inside the stem-ring electrodes, and each port allows a rod electrode group to pass through. Each rod electrode group is connected to the stem-ring electrode.

[0012] In an alternative implementation, the energy change of a particle after one acceleration unit in a radio frequency quadrupole accelerator follows the expression below:

[0013] ΔW=qE0TI0(κa)l cosφ s ;

[0014]

[0015] Where T is the transit time factor, φ s For synchronization phase, E0 is the average value of the electric field peak in one acceleration unit, V is the inter-electrode voltage, A is a parameter representing the acceleration capability of the RF quadrupole field, m is the electrode modulation parameter, a is the minimum aperture of the beam channel, βλ is the modulation period, and λ is the RF wavelength.

[0016] In an optional embodiment, the acceleration chamber is provided with multiple sets of tuner assemblies that are equally spaced apart, each set of tuner assemblies having two couplers symmetrically arranged on both sides of the acceleration chamber.

[0017] In one alternative implementation, a cooling water circuit is symmetrically arranged on the surface of the acceleration chamber.

[0018] In one optional embodiment, the ion source is provided with N laser ion sources, each laser ion source is correspondingly located at the entrance of a beam channel, and the ions excited by the N laser ion sources have different mass-to-charge ratios.

[0019] In one optional embodiment, each laser ion source includes an inner target chamber, a laser, a first plane mirror, a second plane mirror, a plano-convex lens, a target surface, and a drift channel. The laser and the first plane mirror are located outside the inner target chamber to drive the laser beam into the inner target chamber. The second plane mirror, the plano-convex lens, and the target surface are located inside the inner target chamber. After passing through the second plane mirror and the plano-convex lens, the laser beam is focused onto the target surface to generate plasma. The drift channel is located at the entrance of the beam channel to allow the plasma to drift to the entrance of the beam channel.

[0020] In an alternative implementation, the inlet of the tapered solenoid is connected to the outlet of the beam channel.

[0021] The beneficial effects of this technical solution are as follows:

[0022] The ion source of this ion accelerator can generate ions with different valence states, and the mass-to-charge ratio (M / q) of ion beams with different valence states is different, meaning it can be composed of ions of any element, providing flexibility for the composition of the final ion beam. The radio frequency quadrupole accelerator has N beam channels in the cavity, each beam channel corresponding to the acceleration of a different ion beam. Multiple beam channels can accelerate ion beams with different mass-to-charge ratios, and at the same time, the beams with different mass-to-charge ratios achieve different acceleration effects, resulting in beams with different energies. The beam intensity can reach the milliampere level. In other words, each ion beam is accelerated and initially and individually focused in the corresponding beam channel of the radio frequency quadrupole accelerator. The N ion beams enter the focusing and focusing device at the same time. In the structure of the focusing and focusing device, the N ion beams are mixed into one beam, and focusing and focusing are achieved in this structure, similar to a "cocktail beam". Finally, the ion beam of the mixed "cocktail beam" is injected into the target chamber through the exit end of the conical solenoid to achieve ion implantation or material irradiation of relevant materials. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of an ion accelerator according to an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the structure of the laser ion source according to an embodiment of this application;

[0025] Figure 3 This is a three-dimensional structural diagram of the radio frequency quadrupole accelerator according to an embodiment of this application;

[0026] Figure 4 This is a longitudinal cross-sectional view of the radio frequency quadrupole accelerator according to an embodiment of this application;

[0027] Figure 5 This is a schematic cross-sectional view of the radio frequency quadrupole accelerator according to an embodiment of this application.

[0028] Explanation of reference numerals in the attached figures: Ion source 1, laser ion source 110, inner target chamber 111, laser 112, first plane mirror 113, second plane mirror 114, plano-convex lens 115, target surface 116, drift channel 117, radio frequency quadrupole accelerator 2, acceleration cavity tube 210, stem ring electrode 220, rod electrode group 230, rod electrode 231, tuner assembly 240, coupler 241, cooling water circuit 250, focusing and beam-gathering device 3, conical solenoid 310, terminal target chamber 4. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Where there is no conflict, the embodiments and features thereof in this application can be combined with each other. For ease of description, the concepts of "first," "second," etc., mentioned in this application are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependencies. The modifications of "a" and "a plurality of" mentioned in this application are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more."

[0031] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0032] refer to Figure 1 This application provides a hybrid four-beam ion accelerator, comprising an ion source 1, a radio frequency quadrupole accelerator 2, a focusing device, and a target chamber 4 arranged sequentially, wherein:

[0033] Ion source 1 is used to continuously generate N ion beams with different mass-to-charge ratios; in this embodiment, there are four ion beams.

[0034] The radio frequency quadrupole accelerator 2 is equipped with N beam channels for simultaneously accelerating N ion beams with different mass-to-charge ratios.

[0035] The focusing device 3 is equipped with a conical solenoid 310 to converge N accelerated ion beams with different mass-to-charge ratios into one beam to form a mixed ion beam with different mass-to-charge ratios.

[0036] Terminal target chamber 4 is used to place the target material and inject the mixed ion beam.

[0037] Compared with the prior art, the ion source 1 of the ion accelerator in this application embodiment can generate ions with different valence states, and the mass-to-charge ratio (M / q) of the ion beams with different valence states is different, that is, it can be composed of ions of any element, providing flexibility for the composition of the final ion beam; the radio frequency quadrupole accelerator 2 has N beam channels in the cavity, each beam channel corresponding to the acceleration of a type of ion beam, and multiple beam channels can accelerate ion beams with different mass-to-charge ratios respectively, so that beams with different mass-to-charge ratios achieve different acceleration effects and obtain beams with different energies. The beam current intensity can reach the milliampere level. In other words, each ion beam is accelerated and initially and individually focused within the beam channel of the radio frequency quadrupole accelerator 2. N ion beams simultaneously enter the focusing and concentrating device 3. Within the structure of the focusing and concentrating device 3, the N ion beams are mixed into one beam, and focusing and concentrating are achieved within this structure, resembling a "cocktail beam." Finally, the ion beam line of the mixed "cocktail beam" is injected into the target chamber 4 through the outlet end of the conical solenoid 310, achieving ion implantation or material irradiation of the relevant materials. In this embodiment, the "cocktail beam" shape can be seen as... Figure 1 The shape of the ion beam shown in the conical solenoid section is such that multiple beams with different mass-to-charge ratios converge from the inlet end of the conical solenoid 310, and then, under the action of the conical solenoid 310, they converge into a single beam at the outlet end and are injected into the target chamber 4.

[0038] like Figure 1 As shown, the focusing device 3 is made of a conical solenoid 310. In this structure, four ion beams are injected into the solenoid, focused, and converge at a point at the end of the solenoid. The inlet of the conical solenoid 310 is connected to the outlet of the beam channel. In this embodiment, N is 4. The four ion beams with different charge-to-mass ratios converge into one beam at the end of the focusing system to form a mixed ion beam. Finally, the focused mixed ion beam hits the target.

[0039] like Figure 3 , Figure 4 and Figure 5 As shown, the radio frequency quadrupole accelerator 2 in this embodiment of the application is provided with an acceleration cavity tube 210, M stem ring electrodes 220 and N rod electrode groups 231 230. Each rod electrode group 231 230 is provided with four rod electrodes 231. The four rod electrodes 231 are correspondingly arranged to form a beam channel. The M stem ring electrodes 220 are distributed at equal intervals along the beam channel, and each stem ring electrode 220 is connected to the acceleration cavity tube 210. The stem ring electrodes 220 are symmetrically provided with N openings, and each opening is correspondingly provided for one rod electrode group 231 230 to pass through. Each rod electrode group 231 230 is connected to the stem ring electrode 220.

[0040] It should be noted that the radio frequency quadrupole accelerator 2 employs symmetrically placed rod electrodes 231. Applying equal but opposite alternating voltages to the opposing and adjacent electrodes creates beam channels for accelerating the ion beam. Multiple beam channels are uniformly distributed within the stem-ring electrode 220. This symmetrical structure reduces cavity detuning. M and N are both positive integers, and M can be set according to acceleration requirements, such as... Figure 5 As shown, in this embodiment of the application, N is 4, and the beam channel is also designed with 4 beam channels. That is, the radio frequency quadrupole accelerator 2 is designed with 4 beam channels in one cavity, which can accelerate ion beams with 4 different charge-to-mass ratios at the same time.

[0041] To further explain, according to the acceleration principle of the radio frequency quadrupole accelerator 2, the energy change of a particle after passing through one acceleration unit in the radio frequency quadrupole accelerator follows the following expression:

[0042] ΔW=qE0TI0(κa)l cosφ s ;

[0043]

[0044] Where ΔW is the energy change of the particle after one acceleration unit, T is the transit time factor, and φ s For synchronization phase, E0 is the average value of the electric field peak in one acceleration unit, V is the inter-electrode voltage, A is a parameter representing the acceleration capability of the radio frequency quadrupole field, m is the electrode modulation parameter, a is the minimum aperture of the beam channel, βλ is the modulation period, λ is the radio frequency wavelength, I0() is the zero-order Bessel function, q is the charge number of the particle (that is, the charge number of the ion), and l is the length of one acceleration unit.

[0045] In the above formula, l = β s λ / 2,β s λ represents the velocity of the synchronizing particles, and λ is the radio frequency wavelength.

[0046] In the design of the radio frequency quadrupole accelerator 2 in this application embodiment, the electrode modulation parameter m, the minimum beam aperture a, and the synchronization phase φ are specified. s These are adjustable parameters, while other parameters are determined at the initial design stage. Therefore, following the above formula, before the equipment is put into operation, different electrode modulation parameters, beam aperture, and synchronization phase are determined and adjusted to obtain different longitudinal acceleration parameters. Combined with beams of different charge-to-mass ratios, different acceleration effects are achieved, resulting in beams of different energies.

[0047] The derivation process of parameter A of the radio frequency quadrupole (RFQ) acceleration capability in the above embodiments of this application can be found below:

[0048] In this embodiment, the potential function of the RFQ accelerator is crucial for solving the equipotential surface geometry of the electrodes and the inter-electrode electric field. The electromagnetic field distribution between the modulation electrodes in the RFQ accelerator can be described by Maxwell's equations:

[0049]

[0050] in, For electric field strength, It represents the magnetic flux density. For electric vector displacement, The magnetic field strength, Let ρ be the current density and ρ be the charge density. When the distance between the electrode and the beam axis is less than the radio frequency wavelength, the electromagnetic field distribution can be considered as a quasi-static approximation, i.e. Using the quasi-static approximation method, Maxwell's equations can be simplified to two independent equations containing only electric and magnetic fields. Furthermore, since only the electric field distribution is of concern in the RFQ, when conducting beam dynamics studies, only the solution needs to be obtained. A single equation suffices, greatly simplifying the calculation process. Using cylindrical coordinates, the electric potential U can be expressed as... Where u(r,θ,z) is the potential function, and ω is the angular frequency of the potential change. As the initial phase, based on the relationship between electric field and electric potential We can obtain that u(r,θ,z) satisfies the Laplace equation:

[0051]

[0052] The equation in cylindrical coordinates can be written as:

[0053] Solving the Laplace equation yields the expression for the potential function as follows:

[0054]

[0055] Where n+s=2q+1 (q=0,1,2……). The above equation is called the general potential function, I. 2s (nkr) is called the 2s-order modified Bessel function. This potential function can be used to calculate the electric field near the beam. This equation contains all higher-order terms, and although it can reflect the electric field distribution formed by electrode cross-sections of arbitrary shapes, solving for the coefficients of the higher-order terms is very cumbersome. In practical solutions, only the first few terms are needed to meet the accuracy requirements; the most commonly used is the binomial potential function. Taking the terms s=0 and n=1, the expression for the RFQ binomial potential function is:

[0056] u(r,θ,z)=A 01 r 2 cos(2θ)+A10 I0(kr)cos(kz);

[0057] The first term in the formula is independent of z and reflects the lateral focusing effect of the electrode, while the second term reflects the longitudinal acceleration effect of the electrode. The zeroth-order Bessel function I0(v) ~ 1 + v 2 / 4. Constant A 01 and A 10 Determined by the geometry of the electrodes, and utilizing the fact that the horizontal and vertical electrodes have the same potential but opposite polarities, two boundary conditions can be obtained.

[0058] (1) When z = 0, if the potential of the horizontal electrode is u = V0 / 2, substituting it into the equation yields:

[0059]

[0060] (2) When z = 0, the potential of the perpendicular electrode is u = -V0 / 2. Substituting this into the equation, we get:

[0061]

[0062] Solving the system of equations simultaneously yields the following:

[0063]

[0064]

[0065] Therefore, it is ordered that: X and A satisfy the following relationship:

[0066] X+AI0(ka)=1; the stronger the longitudinal electric field used for acceleration, the weaker the transverse focusing electric field, and the larger the modulation coefficient m, the stronger the longitudinal acceleration effect. The above obtains the parameter A of the radio frequency quadrupole acceleration capability of the embodiment of this application.

[0067] like Figure 4 and Figure 5 As shown, the accelerator tube 210 of this application is provided with multiple sets of tuner assemblies 240 distributed at equal intervals. Each set of tuner assemblies 240 is provided with two couplers 241. The two couplers 241 are symmetrically arranged on both sides of the accelerator tube 210, which makes the structure more reasonable and compact. The surface of the accelerator tube 210 is symmetrically provided with cooling water circuits 250. Cooling water is used to treat the accelerator by circulating cooling water through the cooling water circuits 250. When circulating cooling water, attention can be paid to whether each channel is completely unobstructed and the flow rate of the water circuit can be detected to see if it meets the water flow rate requirements. This can prevent the tube from deforming and detuning due to the large amount of heat generated during the acceleration of the beam.

[0068] There are several ways to continuously generate N ion beams with different mass-to-charge ratios using ion source 1. One way is to use a laser ion source, and another way is to use an electron cyclotron resonance ion source. For applications with stricter requirements for simultaneity, a laser ion source is preferred. The embodiment of this application uses a laser ion source.

[0069] like Figure 2 As shown, ion source 1 has N laser ion sources 110, each laser ion source 110 corresponding to the entrance of a beam channel. The N laser ion sources 110 produce ions with different mass-to-charge ratios. The laser ion sources 110 focus a high-power laser beam onto the surface of a solid target, generating a high-temperature, high-density plasma through laser ablation. Once formed, the plasma expands along the normal direction of the target surface within a certain cone angle range under the influence of the density gradient, forming an ion beam. The laser ion sources 110 are characterized by high current, high charge state, and short pulses. Combined with... Figure 5 In this embodiment of the application, the ion source 1 is provided with four laser ion sources 110. The four laser ion sources 110 are simultaneously excited to generate ions, which enter the beam channel for acceleration.

[0070] refer to Figure 2 Each laser ion source 110 includes an inner target chamber 111, a laser 112, a first plane mirror 113, a second plane mirror 114, a plano-convex lens 115, a target surface 116, and a drift channel 117. The laser 112 and the first plane mirror 113 are located outside the inner target chamber 111 to direct the laser beam into the inner target chamber 111. The second plane mirror 114, the plano-convex lens 115, and the target surface are located inside the inner target chamber 111. After passing through the second plane mirror 114 and the plano-convex lens 115, the laser beam is focused onto the target surface 116 to generate plasma. The drift channel 117 is located at the entrance of the beam channel to allow the plasma to drift to the entrance of the beam channel. In this embodiment, the laser beam is incident at a certain angle and focused onto the target surface by the plano-convex lens 115 to generate plasma. The plasma passes through a section of the drift channel 117 at the front end of the inner target chamber 111 and drifts to the entrance of the electrode of the beam channel, where it is then extracted.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions created by the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions created by the present invention without departing from the essence and scope of the technical solutions created by the present invention.

Claims

1. A hybrid four-beam ion accelerator, characterized in that, It includes, in sequence, an ion source, a radio frequency quadrupole accelerator, a focusing device, and a target chamber, wherein: An ion source is used to continuously generate N different mass-to-charge ratio ion beams. The radio frequency quadrupole accelerator has N beam channels to simultaneously accelerate N ion beams with different mass-to-charge ratios. The focusing device is equipped with a conical solenoid to converge N accelerated ion beams with different mass-to-charge ratios into a single beam, forming a mixed ion beam with different mass-to-charge ratios. The terminal target chamber is used to place the target material and inject the mixed ion beam; The radio frequency quadrupole accelerator is equipped with an acceleration cavity tube, M stem ring electrodes and N rod electrode groups. Each rod electrode group has four rod electrodes, which are arranged to form a beam channel. The M stem ring electrodes are distributed at equal intervals along the beam channel and each stem ring electrode is connected to the acceleration cavity tube. N ports are symmetrically opened in the stem ring electrodes, and each port allows a rod electrode group to pass through. Each rod electrode group is connected to the stem ring electrode. The ion source is equipped with N laser ion sources, one laser ion source is set at the entrance of one beam channel, and the mass-to-charge ratio of the ions excited by the N laser ion sources is different. Each laser ion source includes an inner target chamber, a laser, a first plane mirror, a second plane mirror, a plano-convex lens, a target surface, and a drift channel. The laser and the first plane mirror are located outside the inner target chamber to drive the laser beam into the inner target chamber. The second plane mirror, the plano-convex lens, and the target surface are located inside the inner target chamber. After passing through the second plane mirror and the plano-convex lens, the laser beam is focused onto the target surface to generate plasma. The drift channel is located at the entrance of the beam channel to allow the plasma to drift to the entrance of the beam channel.

2. The ion accelerator according to claim 1, characterized in that, The energy change of a particle after one acceleration unit in a radio frequency quadrupole accelerator follows the following expression: ； ； ； in, This represents the energy change of a particle after one acceleration unit. For the transit time factor, For longitudinal wavenumber, To be synchronized phase, The average value of the electric field peak value within one acceleration unit. This is the inter-electrode voltage. The parameter representing the acceleration capability of the radio frequency quadrupole field is... These are electrode modulation parameters. The minimum aperture of the beam channel, For the modulation period, For radio frequency wavelengths, Let be the zeroth-order Bessel function. The charge number of the particle. The length of one acceleration unit.

3. The ion accelerator according to claim 1, characterized in that, The acceleration chamber is equipped with multiple sets of tuner assemblies that are evenly spaced. Each set of tuner assemblies has two couplers, which are symmetrically arranged on both sides of the acceleration chamber.

4. The ion accelerator according to claim 1, characterized in that, The surface of the acceleration chamber is symmetrically equipped with cooling water circuits.

5. The ion accelerator according to claim 1, characterized in that, The inlet of the tapered solenoid is connected to the outlet of the beam channel.

6. The ion accelerator according to claim 1, characterized in that, The mixed ion beams are in the form of a "cocktail" of ion beams.

Images