Charged particle beam transport apparatus and method for neutralizing charged particle beam

Abstract

To provide a charged particle beam transport apparatus that achieves more stable and longer-time supply of a charged particle beam than ever, and a method for neutralizing the charged particle beam.SOLUTION: A charged particle beam transport apparatus 20 comprises: one or more inlets 8a, 8b and 8c for injection of a neutralizer for neutralizing a space charge, which are arrayed along a beam orbit; and flow controllers 9a, 9b and 9c and a control device 12 for controlling an injection rate of the neutralizer from the inlets 8a, 8b and 8c. The injection rate is controlled on the basis of evaluation of a space charge distribution and a beam loss rate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a charged particle beam transport device and a method for neutralizing a charged particle beam.

Background Art

[0002] As an example of a technique for correcting the space charge effect with high uniformity in the plane of the electron orbit, reducing the loss of the electron beam due to the collision between electrons and ions, efficiently neutralizing the space charge, and increasing the beam current to achieve high throughput, Patent Document 1 discloses a device having a function of converging an electron beam emitted from an electron gun, and including ion generation means provided around the orbit region of the electron beam and ion irradiation means for irradiating an ion beam generated by the ion generation means onto the orbit region of the electron beam. By irradiating the ion beam onto the orbit region of the electron beam, the space charge formed by the electron beam is neutralized and the space charge effect is reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the transport of a charged particle beam, charged particles in the beam diverge due to Coulomb repulsion. This beam divergence is called the space charge effect. To suppress this space charge effect, charged particles having a charge opposite to that of the charged particles in the beam are irradiated onto the beam orbit. As a result, both positive and negative charged particles exist on the beam orbit, so the space charge is reduced.

[0005] A technique for suppressing the space charge effect on an electron beam is described in Patent Document 1.

[0006] However, when a neutralizer is incident to reduce the space charge effect of a charged particle beam, a reaction also occurs in which the charged particle beam itself is neutralized by the reaction between the charged particle beam and the neutralizer. Since the neutralized beam cannot be accelerated or orbit-controlled by electromagnetic interaction, it is lost during beam transport. That is, it is necessary to effectively reduce the space charge while minimizing the loss of the charged particle beam.

[0007] For this purpose, it is necessary to increase the incident amount of the neutralizer in the part where the orbits of the charged particle beams are concentrated and the space charge is high, while reducing the injection amount of the neutralizer in the region where the orbits are wide and the space charge is low.

[0008] Patent Document 1 describes a method of uniformly neutralizing the space charge in the vertical plane by irradiating an ion beam from an axisymmetric direction in the vertical plane with respect to the orbit of the electron beam. In addition, a device is described that efficiently reduces the space charge effect by adjusting the irradiation position of the ion beam according to the magnitude of the current density.

[0009] However, the technique described in Patent Document 1 is premised on the neutralization of local space charge in a small system such as an electron beam exposure apparatus.

[0010] In a large-scale device such as an industrial or medical charged particle beam accelerator, it is necessary to control the injection amount and the like in consideration of the distribution after injecting the neutralizer. In addition, control of the neutralizer distribution considering the beam loss due to the interaction between the charged particle beam and the neutralizer is required.

[0011] For a long-term stable supply of charged particle beams, a device is required to control the incident amount and distribution of the neutralizer according to the state changes of the charged particle beam and the device.

[0012] The present invention provides a charged particle beam transport device and a charged particle beam neutralization method that realize a long-term stable supply of charged particle beams as compared with the prior art.

Means for Solving the Problems

[0013] The present invention includes a plurality of means for solving the above problems. For example, a charged particle beam transport device includes one or more neutralizer injection units that inject a neutralizer for neutralizing space charge, arranged along a beam orbit, and an injection amount control device that controls the injection amount of the neutralizer from the neutralizer injection unit, and controls the injection amount based on an evaluation of the space charge distribution and the beam loss rate.

Effect of the Invention

[0014] According to the present invention, it is possible to realize a stable supply of charged particle beams for a longer time compared to the prior art. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the charged particle beam transport device and the neutralization method of the charged particle beam of the present invention will be described with reference to the drawings. In the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated descriptions of these components may be omitted.

[0017] <First Embodiment> A first embodiment of the charged particle beam transport device and the neutralization method of the charged particle beam of the present invention will be described with reference to FIGS. 1 and 2.

[0018] First, the overall configuration of the charged particle beam transport device will be described with reference to FIG. 1. FIG. 1 is a schematic configuration diagram of the charged particle beam transport device according to the first embodiment.

[0019] The charged particle beam transport device 20 shown in FIG. 1 is a device for transporting charged particles generated by the plasma generation device 1 to subsequent devices, and is composed of a charged particle beam 2, a vacuum chamber 3, a convergence coil 4, a deflection electromagnet 5, inlets 8a, 8b, 8c, flow regulators 9a, 9b, 9c, measuring devices 10a, 10b, 10c, an arithmetic device 11, a control device 12, and the like.

[0020] The plasma generation device 1 is a device for generating a charged particle beam. Examples of its types include, for example, a microwave ion source, an ECR (Electron Cyclotron Resonance) ion source, a duoplasmatron, an electron gun, etc., and any of these devices can be used. In this embodiment, a configuration employing a microwave ion source will be described as an example.

[0021] The plasma generated in the plasma generation device 1 is extracted by the potential difference with the extraction electrode 6, and a charged particle beam 2 is generated.

[0022] The charged particle beam 2 is converged by the convergence coil 4 in the vacuum chamber 3, deflected by the deflection electromagnet 5, and transported to subsequent devices such as a subsequent accelerator. Here, the convergence coil 4 can be provided with magnetic poles using a magnetic material.

[0023] Here, the post-stage accelerator includes, for example, a high-frequency accelerator such as an RFQ (Radio Frequency Quadrupole) or a DTL (Drift Tube Linac), and either one or both of them can be used. Alternatively, it can also be an electrostatic accelerator such as a Cockcroft-Walton type or a Van de Graaff type. Further, it can also be an electromagnet for orbit control or a neutralization cell for neutralizing the beam, etc.

[0024] When the charged particle beam 2 is transported in the vacuum chamber 3 or the like, it diverges due to the Coulomb repulsion between the charged particles constituting the charged particle beam 2. This is called the space charge effect.

[0025] The beam divergence due to the space charge effect can be expressed by the following equation (1).

[0026] [Number]

[0027] In equation (1), F is the force acting on the charged particles constituting the charged particle beam 2, and it is expressed as a function of the electric field E and magnetic flux density B in the direction perpendicular to the beam propagation direction as in the second term, as well as the elementary charge e and velocity v. As can be seen from the above equation, the forces due to the electric field and magnetic field cancel each other out.

[0028] When this is transformed into a function form of the elementary charge e, charge density ρ 0 , permittivity ε 0 , distance r from the central orbit, speed of light c, and velocity v as in the third term, it can be seen that the lower the velocity, the greater the divergence force.

[0029] From equation (1), it can be seen that the low-energy charged particle beam 2 before acceleration is more strongly affected by the space charge effect and diverges.

[0030] As an index indicating the divergence of the charged particle beam 2, there is the emittance represented by the phase space area of the positions and momenta of the charged particles constituting the beam. The emittance increased due to the space charge effect or the like cannot be reduced unless a special process called beam cooling is used.

[0031] For example, when the charged particle beam 2 is converged by the converging coil 4, the charged particles constituting the charged particle beam 2 can be converged to the orbit center, but on the other hand, the momentum dispersion becomes large. Therefore, even if the charged particle beam 2 is converged by the converging coil 4, the emittance cannot be decreased.

[0032] A large emittance means that the orbit of the charged particle beam 2 diverges or the momentum dispersion of the charged particles constituting it is large, and it deviates from the stable control region in the subsequent transport system or accelerator and is lost.

[0033] In order not to increase the emittance, it is necessary to reduce the Coulomb force expressed by equation (1). Since the Coulomb force is proportional to the charge density, the charge density on the orbit of the charged particle beam 2 must be reduced.

[0034] Here, reducing the charge density on the orbit of the charged particle beam 2 means that charged particles having a charge opposite to that of the charged particle beam 2 are arranged on the orbit to spatially reduce the charge. This is called reduction or neutralization of space charge.

[0035] In order to neutralize the space charge, there is a method of injecting a neutralizing agent onto the orbit of the charged particle beam 2. Here, the neutralizing agent may be a neutral gas, an electron beam, an ion beam, or a plasma.

[0036] For example, when a neutral gas is injected onto the orbit of the charged particle beam 2, a reaction occurs in which the charged particles in the beam react with the neutral gas and electrons are ionized from the neutral gas.

[0037] When the charged particle beam 2 is composed of positively charged ions, electrons ionized from the neutral gas are accumulated on the orbit by the Coulomb force with the beam particles. On the other hand, the ions ionized from the neutral gas are removed from the beam orbit because they receive a repulsive force from the charged particle beam 2. In this way, the space charge is neutralized by the accumulation of electrons on the orbit of the charged particle beam 2 having a positive charge.

[0038] Even when an electron beam, an ion beam, and a plasma are used as neutralizing agents, the beam neutralization process excluding the ionization process of the neutral gas is the same.

[0039] In this embodiment, an example in which a neutral gas is used as the neutralizing agent will be described.

[0040] The inlets 8a, 8b, 8c are provided with one or more for injecting a neutralizing agent that neutralizes the space charge, which are arranged along the beam orbit. In this embodiment, the case of providing three is shown as an example, but the number of inlets is not limited to three and can be one or more. Also, a plurality of beam orbits can be provided at the same position.

[0041] The flow rate regulators 9a, 9b, 9c are provided on the pipes connecting the cylinders 7 containing the neutral gas and the inlets 8a, 8b, 8c, respectively, and adjust the injection amount of the neutralizing agent from the inlets 8a, 8b, 8c. The control amount for controlling the injection amount is adjusted by the control device 12. It is desirable to provide the same number of flow rate regulators as the number of inlets. In this embodiment, the case of providing three is shown as an example, but the number of flow rate regulators is not limited to three and can be one or more. Also, a plurality of flow rate regulators can be provided at the same position in the orbital direction of the beam. In that case, it is desirable to change the position in the radial direction.

[0042] The measuring instruments 10a, 10b, 10c are measuring instruments for measuring the beam orbit or the charge density, and can be various measuring instruments such as destructive types using wires or electrodes, or non-destructive types using gases or optical sensors.

[0043] Similar to the inlets 8a, 8b, 8c and the flow regulators 9a, 9b, 9c, the installation positions and the number of the measuring instruments 10a, 10b, 10c do not necessarily have to be the same as those of the inlets 8a, 8b, 8c, etc. of the neutralizing agent. The trajectory of the charged particle beam 2 outside the measurement range of the measuring instruments 10a, 10b, 10c can be estimated from the measured values by beam trajectory calculation or the like. Alternatively, the beam trajectory of the entire beam transport device may be estimated only by beam trajectory calculation without installing the measuring instruments 10a, 10b, 10c.

[0044] The arithmetic unit 11 is a part for evaluating the space charge distribution and the beam loss rate, and preferably evaluates the space charge distribution on the beam trajectory based on the beam trajectory measured by the measuring instruments 10a, 10b, 10c or the charge density, the distribution of the neutralizing agent, and the injection amount of the neutralizing agent is obtained based on the calculation result of the beam loss rate, and a signal regarding the obtained injection amount is output to the control device 12.

[0045] The control device 12 receives the signal, obtains the adjustment amounts of the flow regulators 9a, 9b, 9c for realizing the injection amounts of the neutralizing agent from the respective inlets 8a, 8b, 8c, and controls the operations of the flow regulators 9a, 9b, 9c.

[0046] These arithmetic unit 11, control device 12, and the recording device 16 of the third embodiment described later are constituted by, for example, a computer having a display device such as a liquid crystal display, an input device, a recording device, a CPU, a memory, and the like. The control of the operations of the respective devices by the arithmetic unit 11 and the control device 12 is executed based on various programs recorded in the recording device.

[0047] Note that the control processes of the operations executed by the arithmetic unit 11 and the control device 12 may be summarized in one program, may be separated into a plurality of programs respectively, or may be a combination thereof. Further, part or all of the programs may be realized by dedicated hardware or may be modularized.

[0048] The neutral gas for reducing the space charge is injected from the inlets 8a, 8b, 8c, and the injection amount is adjusted by the flow regulators 9a, 9b, 9c.

[0049] When the amount of the neutralizing agent injected is insufficient, the charged particle beam 2 diverges due to insufficient neutralization of the space charge. On the other hand, when the amount of the neutralizing agent injected is excessive, the charged particle beam 2 is neutralized by the interaction between the charged particles in the charged particle beam 2 and the charged particles having the opposite charge.

[0050] Since the neutralized charged particle beam 2 is not deflected by the deflection electromagnet 5, it is not transported to the subsequent equipment and is lost. Since the neutralized beam cannot be controlled by electromagnetic force, the orbit cannot be controlled and is lost even in configurations other than the present embodiment.

[0051] In order to suppress beam divergence by space charge neutralization up to the specifications required by the device while minimizing the loss of the charged particle beam 2 due to neutralizing agent injection, it is necessary to control the distribution of the neutralizing agent according to the space charge distribution on the beam orbit.

[0052] In a region where the space charge on the beam orbit is high, the beam divergence due to the space charge effect is large, so it is necessary to increase the neutralizing agent density. On the other hand, in a region where the space charge on the beam orbit is low, since the space charge effect is small, it is necessary to reduce the neutralizing agent density in consideration of the loss due to beam neutralization.

[0053] As described above, by measuring the orbit and charge density of the charged particle beam 2 with the measuring instruments 10a, 10b, and 10c, the space charge distribution on the beam orbit at that time can be evaluated almost in real time.

[0054] Here, for the beam orbit calculation, linear calculations using transfer matrices or numerical simulations such as Particle In Cell (PIC) can be used.

[0055] By the above orbit calculation, the charge distribution on the orbit of the charged particle beam 2 can be evaluated, so that the amount and distribution of the neutral gas required for neutralization can be determined.

[0056] The neutral gas distribution in the vacuum chamber 3 can be calculated by molecular flow simulation assuming that the mean free path is sufficiently long.

[0057] The number of electrons ionized from the neutral gas can be expressed by the velocity, cross-sectional area, and respective density of the charged particle beam 2. The generated electrons diffuse and disappear due to the energy at the time of generation, the distribution of the space potential, recombination with the charged particle beam 2, and the like.

[0058] The electron density on the orbit of the charged particle beam 2 when the neutral gas is injected is expressed by Equation (2).

[0059]

Equation

[0060] In Equation (2), ρ e , ρ i and ρ n represent the densities of electrons, beam particles, and neutral gas. σ, v, and d represent the cross-sectional area between the beam and the neutral gas, the velocity of the beam particles, and the diffusion / disappearance coefficient.

[0061] The density ρ i and ρ n can be determined by beam orbit calculation, molecular flow simulation, etc. The velocity v of the beam particles is determined by the acceleration conditions. Also, the cross-sectional area σ can refer to the cross-sectional area data.

[0062] The diffusion / disappearance coefficient d can be obtained by numerical calculations using PIC or fluid models. It can also be determined experimentally.

[0063] Also, the neutralization rate of the charged particle beam 2 by neutral gas injection can be determined by numerical simulation or experimentally.

[0064] By incorporating the electron density and neutralization rate on the orbit of the charged particle beam 2 into the beam orbit calculation, the emittance after space charge neutralization can be evaluated.

[0065] The orbit calculation considering space charge neutralization can be achieved by multiplying the charge density by the space charge neutralization rate in the Poisson equation during the calculation, as shown in Equation (3).

[0066]

Number

[0067] In Equation (3), ΔΦ is the potential, ρ is the charge density of the charged particle beam 2, and ε 0 represents the permittivity of vacuum. By multiplying this charge density ρ by the space charge neutralization rate α, the potential when the space charge is neutralized can be calculated.

[0068] The space charge neutralization rate α can be expressed by Equation (4) obtained by dividing Equation (2) by the charge density ρ of the charged particle beam 2. i

[0069]

Number

[0070] Also, since the beam neutralization rate is proportional to the number of electrons on the beam orbit, the beam loss rate due to neutralization can also be obtained.

[0071] The beam orbit calculation considering space charge neutralization as described above may also be a method of solving all the interactions between the charged particle beam 2 and the particles of the neutral gas by the Monte Carlo method. However, due to the current computer performance, it is impossible to calculate the behavior of all charged particles, so it is an approximate method of calculating only super particles collected from a large number of particles.

[0072] In addition, calculation methods such as fluid simulation can also be applied. However, since there are problems with experimental reproducibility, it is necessary to apply an appropriate calculation method for each evaluation system.

[0073] From the above, the neutralizer distribution required for the beam orbit calculation of the entire beam transport device can be calculated.​

[0074] In actual operation, preferably, based on the beam trajectories measured by the measuring instruments 10a, 10b, and 10c, the computing device 11 evaluates the space charge distribution of the entire beam transport device and the required neutral gas distribution. Based on this evaluation result, the control device 12 controls the plurality of flow regulators 9a, 9b, and 9c to adjust the injection amount of the neutralizing agent from the inlets 8a, 8b, and 8c.

[0075] The control flow of the injection amount and position of the neutralizing agent in this embodiment will be described with reference to FIG. 2. FIG. 2 is a diagram showing the control flow of the injection amount of the space charge neutralizing agent.

[0076] Step S101: The measuring instruments 10a, 10b, and 10c measure the trajectory and current density of the charged particle beam 2.

[0077] Step S102: Based on the measurement results of the measuring instruments 10a, 10b, and 10c measured in step S101, the computing device 11 calculates the space charge distribution on the beam trajectory and the required neutralizing agent distribution.

[0078] Step S103: Calculate the neutralizing agent distribution by molecular flow simulation when the injection amounts from the inlets 8a, 8b, and 8c are changed.

[0079] Step S104: Determine whether the neutralizing agent distribution calculated in step S103 meets the required value. If it does not meet the required value, return to step S103 and calculate the neutralizing agent distribution under different conditions. If it meets the required value, proceed to step S105.

[0080] Step S105: The control device 12 controls the flow regulators 9a, 9b, and 9c to adjust the injection amount of the neutralizing agent so as to meet the conditions satisfied in step S104.

[0081] Step S106: Determine whether the beam meets the target value in step S105. Here, other than emittance, the beam divergence amount may also be used as an index for the beam divergence. If the emittance and the beam loss rate meet the target values, end the control flow. On the other hand, if the emittance and the beam loss rate do not meet the target values, execute step S107.

[0082] Step S107: When the target value is not met in step S106, add the difference between the calculation result after the neutralizer distribution adjustment and the measurement result as a correction amount, and re - execute the calculation in step S102 to re - execute the control flow.

[0083] Next, the effects of this embodiment will be described.

[0084] The charged particle beam transport device 20 of the first embodiment of the present invention described above includes one or more inlets 8a, 8b, 8c for injecting a neutralizer that neutralizes space charge, which are arranged along the beam orbit, flow regulators 9a, 9b, 9c for controlling the injection amount of the neutralizer from the inlets 8a, 8b, 8c, and a control device 12, and controls the injection amount based on the evaluation of the space charge distribution and the beam loss rate.

[0085] As a result, for all charged particle beams, considering the charged particle beam orbit and the neutralizer distribution in the entire beam transport system, the injection amount and position of the neutralizer are controlled. By efficiently reducing the space charge while suppressing the loss due to beam neutralization, low - divergence and high - efficiency beam transport is realized. Therefore, compared with the prior art, it is possible to realize a stable supply of charged particle beams for a long time.

[0086] Such a charged particle beam transport device 20 is suitable for a linear accelerator. In addition, it is applicable to an ion supply source in a fusion power reactor, boron neutron capture therapy (BNCT), or a particle beam therapy device using a synchrotron - type accelerator.

[0087] Furthermore, it further includes an arithmetic unit 11 for evaluating the space charge distribution and the beam loss rate. The arithmetic unit 11 can realize the injection amount control of the neutralizing agent according to the state of the charged particle beam by using the above-described processing in order to obtain the injection amount based on the space charge distribution on the beam trajectory, the distribution of the neutralizing agent, and the calculation result of the beam loss rate.

[0088] Furthermore, it further includes measuring instruments 10a, 10b, and 10c for measuring the beam trajectory or the charge density. By evaluating the space charge distribution based on the beam trajectory or the charge density measured by the measuring instruments 10a, 10b, and 10c, the injection amount control of the neutralizing agent according to the state of the charged particle beam at any time can be realized.

[0089] In the above-described embodiment, a form in which the arithmetic unit 11 evaluates the space charge distribution and the beam loss rate using the measurement results of the measuring instruments 10a, 10b, and 10c is illustrated. However, a form in which an operator evaluates the space charge distribution and the beam loss rate using the measurement results of the measuring instruments 10a, 10b, and 10c may also be used. In this case, the injection amount of the neutralizing agent for neutralizing the space charge is also manually controlled by the operator.

[0090] Furthermore, without providing the measuring instruments 10a, 10b, and 10c, the space charge distribution and the beam loss rate are evaluated in advance by beam trajectory calculation or the like at the design and manufacturing stages of the charged particle beam transport device 20, and the injection amount of the neutralizing agent is automatically or manually controlled based on the evaluation results at the design and manufacturing stages.

[0091] <Second Embodiment> The charged particle beam transport device and the neutralization method of the charged particle beam according to the second embodiment of the present invention will be described with reference to FIG. 3. FIG. 3 is a schematic configuration diagram of the charged particle beam transport device according to the second embodiment.

[0092] The charged particle beam transport device 20A of the present embodiment shown in FIG. 2 is a system that uses either electrons or ions as a neutralizing agent and generates electrons or ions to neutralize the space charge on the beam trajectory.

[0093] When an electron beam, an ion beam, and plasma are used as neutralizing agents, an electron gun, an ion source, a plasma source, etc. are used, and the injection amount is controlled by the device configuration such as the voltage, current, or incident angle applied respectively.

[0094] For example, along the orbit of the charged particle beam 2, one or more ion generation devices 13a, 13b are arranged to generate an ion beam having a charge opposite to that of the charged particle beam 2. The ion generation method may be a filament or a microwave.

[0095] The ions generated by the ion generation devices 13a, 13b are irradiated onto the orbit of the charged particle beam 2 by a potential difference.

[0096] The irradiation amount of the ion beam can be controlled by the current or voltage supplied from the power supply 14. Also, the irradiation amount of the ion beam can be controlled by changing the flow rate of the gas injected into the ion generation devices 13a, 13b to generate ions.

[0097] The irradiation amount of the ion beam is controlled in the same manner as in Embodiment 1.

[0098] Similar to Embodiment 1, based on the orbit of the charged particle beam 2 measured by the measuring instruments 10a, 10b, 10c, the arithmetic unit 11A calculates the space charge distribution and the required neutralizing agent distribution. Then, based on the calculation result, the irradiation amount of the ion generation devices 13a, 13b is adjusted.

[0099] The other configurations and operations are substantially the same as those of the charged particle beam transport device and the charged particle beam neutralization method of the first embodiment described above, and the details are omitted.

[0100] Also in the charged particle beam transport device and the charged particle beam neutralization method of the second embodiment of the present invention, substantially the same effects as those of the charged particle beam transport device and the charged particle beam neutralization method of the first embodiment described above can be obtained.

[0101] <Third Embodiment> The charged particle beam transport device and the neutralization method of the charged particle beam according to the third embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic configuration diagram of the charged particle beam transport device according to the third embodiment, and FIG. 5 is a diagram showing an example of the outline of the data recorded in the recording device.

[0102] The charged particle beam transport device 20B of the present embodiment shown in FIG. 4 replaces the arithmetic device 11 in the charged particle beam transport device 20 of the first embodiment with a recording device 16 having a table in which the injection amounts of the neutralizing agent for each beam condition are recorded, and the flow rate regulators 9a, 9b, 9c, and the control device 12B is configured to control the injection amount by referring to the table for each beam condition.

[0103] In the present embodiment, for the injection amounts of the neutralizing agent from the respective inlets 8a, 8b, 8c, the emittance and the beam loss rate are measured in advance or calculated in advance, and the measurement or calculation results are stored in the recording device 16. The data stored in the recording device 16 is a table of the emittance and the beam loss rate for each injection amount of the neutralizing agent as shown in FIG. 5.

[0104] Furthermore, the control device 12B refers to the necessary injection amount of the neutralizing agent according to the beam conditions to be used, and adjusts the flow rate regulators 9a, 9b, 9c based on the reference result.

[0105] In the translation embodiment, when the conditions of the beam to be used change, it is necessary to create a table for each beam condition. In addition, in order to control the injection amount of the neutralizing agent in response to the beam conditions that change during operation, it is necessary to prepare a table comprehensively for the beam conditions.

[0106] The other configurations and operations are substantially the same as those of the charged particle beam transport device and the charged particle beam neutralization method of the first embodiment described above, and the details are omitted.

[0107] Also in the charged particle beam transport device and the charged particle beam neutralization method according to the third embodiment of the present invention, substantially the same effects as those of the charged particle beam transport device and the charged particle beam neutralization method of the first embodiment described above can be obtained.

[0108] Further, it includes a recording device 16 having a table recording the injection amount of the neutralizing agent for each beam condition. The flow rate regulators 9a, 9b, 9c and the control device 12B refer to the table for each beam condition and control the injection amount, so that the calculation time as in the first embodiment is not required, enabling fast control.

[0109] Note that also in the third embodiment, the form is not limited to using a neutral gas as the neutralizing agent, and it can be a form in which electrons or ions are injected as in the second embodiment.

[0110] <Others> Note that the present invention is not limited to the above-described embodiments and includes various modifications. The above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

[0111] Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

Description of Reference Numerals

[0112] 1... Plasma generation device 2... Charged particle beam 3... Vacuum chamber 4... Convergence coil 5... Deflection electromagnet 6... Extraction electrode 7... Gas cylinder 8a, 8b, 8c... Injection port (neutralizing agent injection part) 9a, 9b, 9c... Flow rate regulator (injection amount control device) 10a, 10b, 10c... Measuring instrument (measuring device) 11, 11A... Arithmetic unit 12, 12B... Control device (injection amount control device) 13a, 13b... Ion generation device 14... Power supply 16…Recording device 20, 20A, 20B…Charged particle beam transport device

Claims

Claim 1 A charged particle beam transport device, comprising: one or more neutralizer injection units that inject a neutralizer for neutralizing space charge, disposed along a beam trajectory; an injection amount control device that controls an injection amount of the neutralizer from the neutralizer injection unit; and controls the injection amount based on an evaluation of a space charge distribution and a beam loss rate Charged particle beam transport device. Claim 2 The charged particle beam transport device according to claim 1, further comprising: an arithmetic device that evaluates a space charge distribution and a beam loss rate, wherein the arithmetic device determines the injection amount based on the space charge distribution on the beam trajectory, the distribution of the neutralizer, and a calculation result of the beam loss rate Charged particle beam transport device. Claim 3 The charged particle beam transport device according to claim 1, comprising: a recording device having a table that records an injection amount of the neutralizer for each beam condition, wherein the injection amount control device controls the injection amount by referring to the table for each beam condition Charged particle beam transport device. Claim 4 The charged particle beam transport device according to claim 2 or 3, further comprising: a measuring instrument that measures the beam trajectory or charge density, wherein the space charge distribution is evaluated based on the beam trajectory or the charge density measured by the measuring instrument Charged particle beam transport device. Claim 5 The charged particle beam transport device according to claim 1, wherein any one of neutral gas, electrons, and ions is used as the neutralizer Charged particle beam transport device. Claim 6 Injecting a neutralizer for neutralizing space charge from one or more neutralizer injection units disposed along a beam trajectory based on an evaluation of a space charge distribution and a beam loss rate Method for neutralizing a charged particle beam.

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