High-current superconducting proton cyclotron beam extraction method based on H2 < + > and stripping target

Abstract

The invention discloses a high-current superconducting proton cyclotron beam extraction method based on H2 < + > and a stripping target. The method comprises the following steps: obtaining K stripping point positions of the stripping target containing a plurality of energies in the radial direction and the angular direction; performing two-dimensional scanning on two parameters of H2 + energy and a stripping film azimuth angle at the positions of the K stripping points by adopting a particle tracking program to obtain m target stripping points; taking the positions of the m target stripping points as the position of a target stripping target; according to the stripping target, two working positions of one stripping target are symmetrical along the two sides of the center line of the valley region. And the target head of the stripping target deviates from the target rod by a set angle as required. Two-dimensional parameter scanning is carried out on two parameters of H2 + energy and a stripping membrane azimuth angle, stripping points meeting conditions are screened, and leading-out tracks of high-current proton beams with different energies are designed, so that the high-current proton beams generated by stripping H2 + are separated from a central area and a high-frequency cavity on the premise of not hitting the central area and the high-frequency cavity; and rotating out of the magnetic pole region within a limited time step and reaching a specified position.

Description

Technical Field

[0001] The present invention belongs to the technical field of cyclotron accelerators, and particularly relates to a cyclotron accelerator based on H2 + A high-current superconducting proton cyclotron beam extraction method and a stripping target. Background Art

[0002] The variable-energy cyclotron can provide beams in different energy ranges to meet the needs of end users. It is a key scientific instrument and an indispensable experimental platform for conducting nuclear equipment development, cutting-edge research in nuclear science and life sciences, and innovative applications of nuclear technology. It plays a vital role in promoting the development of modern nuclear science.

[0003] Currently, the vast majority of commercial cyclotrons are proton cyclotrons, most of which cannot achieve continuous adjustment of the extracted energy and require the use of an energy degrader or a range shifter at the terminal to change the energy of the particles.

[0004] In order to realize the technical feature of variable energy, most room-temperature accelerators use negative hydrogen for acceleration, and place a carbon film at the extraction point to strip off protons. For negative hydrogen cyclotron accelerators, negative hydrogen becomes protons after passing through the stripping film. The charge of protons is opposite to that of negative hydrogen and is directly deflected outward. Therefore, the stripping extraction of negative hydrogen or the stripping extraction of variable energy is relatively easy. However, negative hydrogen has obvious Lorentz stripping phenomenon in the magnetic field. Therefore, the magnetic field in the accelerator cannot be greater than 1.5T, otherwise it will cause serious beam loss. Therefore, negative hydrogen is difficult to be accelerated in a superconducting cyclotron accelerator.

[0005] Compared with negative hydrogen, H2 + The Lorentz stripping phenomenon is not obvious during the acceleration process, and it can be accelerated in a superconducting cyclotron. Two protons can be produced by stripping, which is very beneficial for the generation of strong beams. However, the protons produced after stripping are different from H2 + With the same charge, the charge-to-mass ratio of protons is about H2 + The charge-to-mass ratio is twice that of the proton, so the proton's trajectory is deflected inwards, and the trajectory radius is about H2 + Half of the protons may hit the central area directly, or the high-frequency cavities on both sides, or they may rotate in the magnetic pole area because of the small trajectory radius, making it difficult to lead out. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a method based on H2 + The high-current superconducting proton cyclotron beam extraction method and stripping target are designed to solve the problem of H2 + After being stripped, the proton's trajectory deflects inward, and the trajectory radius is about H2 +Half of the protons may hit the central area directly, or the high-frequency cavities on both sides, or they may rotate in the magnetic pole area because of the small trajectory radius, making it difficult to lead out the problem.

[0007] The present invention proposes the following technical solutions to solve the technical problems:

[0008] A H2-based + The high-current superconducting proton cyclotron beam extraction method is characterized in that it comprises the following steps:

[0009] Step 1: obtaining K stripping point positions of a stripping target with multiple energies in radial and angular directions; the stripping target is a stripping target with two working positions in the same valley of a high-current superconducting proton cyclotron; the K stripping points are the total stripping points of the stripping target at the two working positions; the K stripping points of multiple energies are stripping points on different energy trajectories; the particle trajectory radius of particles with large energy is relatively large, and the particle trajectory radius of particles with small energy is relatively small;

[0010] Step 2: Use particle tracking program to track H2 at K peeling points + The energy and stripping film azimuth are scanned in two dimensions; the target particle trajectory is determined as follows: the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area, and the stripping points that meet the target particle trajectory selected above are used as n candidate stripping points, and m target stripping points are determined from the n candidate stripping points; the m target stripping points are the stripping points that can enter the central area of ​​the lead-out area entrance;

[0011] Step 3: using the positions of the m target stripping points as the position of the target stripping target; the position of the target stripping target includes a target radial position and a target angular position;

[0012] Step 4: Calculate the physical parameters of the trajectories of m target peeling points focused on the center point of the focusing element exit.

[0013] Furthermore, the step 2 of determining m target stripping points from n candidate stripping points is specifically as follows:

[0014] 1) A focusing element is arranged in the lead-out area, and the position of the focusing element is the position where the m target stripping point trajectories will pass;

[0015] 2) Select m target stripping points from the n candidate stripping points, whose positions are in the region of the center point of the focusing element entrance and whose speed directions are as close as possible to the direction of the symmetry axis of the focusing element;

[0016] 3) The positions of the m target peeling points are used as the positions of the target peeling targets.

[0017] Furthermore, the physical parameters of the trajectory of the m target peeling points in step 4 are focused on the center point of the focusing element outlet, specifically:

[0018] 1) Calculate the velocity directions of the m target peeling point particles in the center point area of ​​the focusing element entrance: Calculate the velocity directions of the m target peeling point particles before they enter the focusing element based on the fringe field of the main magnet, so that the direction of the particle velocity is approximately perpendicular to the edge line of the center point area of ​​the focusing element entrance;

[0019] 2) Calculate the velocity directions of the m target peeling point particles at the center point of the focusing element exit: superimpose the magnetic field of the focusing element on the edge field of the main magnet, calculate the velocity directions of the m target peeling point particles after entering the focusing element under the condition of the superposition of the two magnetic fields, and adjust the magnetic field of the focusing element according to the velocity directions, so that particles of different energies are focused on the center point of the focusing element exit, and the velocity direction of the particles at the center point of the focusing element exit is the same as the direction of the symmetry axis of the focusing element;

[0020] 3) Saving the adjusted magnetic field of the focusing element;

[0021] 4) determining the physical design of the focusing element according to the adjusted magnetic field of the focusing element;

[0022] Furthermore, the center point area of ​​the process 2) of step two refers to the entrance center point area when the particle trajectories of the m target stripping points can be focused on the exit center point of the focusing element when passing through the focusing element after the focusing element magnetic field and the main magnetic field are superimposed.

[0023] A double-working-position stripping target is characterized in that one stripping target has two working positions in the same valley area, and the two working positions are symmetrical along the center line of the valley area.

[0024] According to claim 5, a dual-working position stripping target is characterized in that: the symmetry on both sides along the center line of the valley area means that: the stripping target positions at the symmetrical points must satisfy that the particle trajectory after stripping cannot enter the central area, and the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area.

[0025] According to a dual working position stripping target as described in claim 5, it is characterized in that: the m target stripping points are the sum of the stripping points that meet the conditions at the two stripping target working positions, and the conditions are: the particle trajectory after stripping cannot enter the central area, and the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area.

[0026] Furthermore, the target head of the stripping target deviates from the target rod by a set angle as required.

[0027] Furthermore, the set angle refers to the angle formed by a line connecting the stripping point and the tail of the target rod and the target rod when a stripping point among the m stripping points is not on a straight line of the target rod.

[0028] Advantages and effects of the present invention

[0029] The effective benefit of the present invention is: by + The energy and stripping film azimuth were used to perform two-dimensional parameter scanning and screening of qualified stripping points, and the extraction trajectories of high-current proton beams with different energies were designed to make the stripping of H2 + The generated high-current proton beam rotates out of the magnetic pole region and reaches the specified position within a limited time step without hitting the central area and high-frequency cavity. On this basis, the mechanical design of the stripping target device and the design of the extraction focusing element were carried out together. Through parameter scanning to select the orbit and the design of the stripping target device and the extraction focusing element, it is possible to extract a high-current proton beam with variable energy in the superconducting cyclotron, breaking through the limitation of the Lorentz stripping phenomenon on the stripping of negative hydrogen from the superconducting cyclotron to extract a variable energy proton beam and the stripping of H2 + The proton beam trajectory is difficult to plan. + The resulting variable energy high-current proton beam can be used for bombarding lithium targets and beryllium targets, proton therapy, and simulation of single-particle effects in deep space radiation environments, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of screening m target stripping points for the present invention;

[0031] Figure 2 A schematic diagram of a stripping target having two working positions according to the present invention;

[0032] Figure 3 The present invention discloses a high-current superconducting proton cyclotron beam extraction method based on H2+ and a flow chart thereof. DETAILED DESCRIPTION

[0033] Design principle of the present invention:

[0034] 1. The innovation of the present invention is to find a beam extraction method for high-current superconducting cyclotron accelerator, which is to extract H2 + The conventional accelerators mostly use negative hydrogen to accelerate, and a carbon film is placed at the extraction point to extract the protons, but negative hydrogen is difficult to be accelerated in a superconducting cyclotron. + Acceleration, compared with negative hydrogen, the advantages are: First, H2 + The Lorentz stripping phenomenon is not obvious during the acceleration process. Second, it can be accelerated in a superconducting cyclotron. Third, unlike the use of negative hydrogen for acceleration, H2+ Two protons can be generated by stripping, which is very beneficial for the generation of strong beams; the present invention uses H2 + Acceleration, the disadvantage compared to negative hydrogen is: H2 + The proton mass number produced after stripping is H2 + and also carries 1 positive charge, so the charge-to-mass ratio of the proton is about H2 + The charge-to-mass ratio is twice that of the proton, so the proton's trajectory is deflected inwards, and the trajectory radius is about H2 + half of the H2, since the proton's trajectory is deflected inwards and has a radius of about + The protons may directly hit the central area, or hit the high-frequency cavities on both sides, or they may rotate in the magnetic pole area due to the small trajectory radius, making it difficult to lead out. The innovation lies in: giving full play to the use of H2 + The advantages of stripping and extraction are overcome by using H2 + In order to overcome the disadvantages of stripping extraction, a beam extraction method for high-current superconducting cyclotron was found.

[0035] 2. Solution of the present invention: The present invention overcomes the problem of using H2 + The specific method of stripping out the disadvantages can be summarized as follows: A. First find m target stripping points that meet the conditions; B. Then determine the position of the stripping target based on the m target stripping points. The difference from the traditional method is that the position of the stripping point in the traditional method is known in advance, so it is a fixed position. Generally, the position of the stripping point is placed on the beam trajectory of the outermost circle of the accelerator. Because the beam trajectory of the outermost circle has the highest energy, the stripping point is placed on the outermost circle; the position of the stripping point of the present invention is screened out from tens of thousands of stripping points, and which stripping points the m target stripping points should be is not known in advance, but known after screening, and the screening is carried out twice; the first time is to screen out n candidate stripping points from K stripping points, and the second time is to screen out m target stripping points from n candidate stripping points.

[0036] 1) First find m target stripping points that meet the conditions: obtain m target stripping points: the m target stripping points meet the following conditions: first, contain multiple energies; second, the particle trajectory after stripping cannot enter the central area, and the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area; third, can enter the entrance central area of ​​the lead-out area; the specific steps are: ① first determine K stripping points containing multiple energies, each energy represents a particle trajectory, the radius of the particle trajectory with high energy is relatively large, and the radius of the particle trajectory with low energy is relatively small; ② select n candidate stripping points that meet the conditions from the K stripping points, the conditions of the n candidate stripping points are: the particle trajectory after stripping cannot enter the central area, and the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area, the above-selected stripping points that meet the target particle trajectory are used as n candidate stripping points, ③ select m target stripping points that can enter the entrance central area of ​​the lead-out area from the n candidate stripping points.

[0037] 2) The position of the stripping target is then determined based on the m target stripping points.

[0038] The difference from the traditional method is that the two stripping targets of the traditional method are two stripping targets arranged symmetrically at 180 degrees, while the stripping target of the present invention is one stripping target, and one stripping target has two working positions, both of which are placed in the same valley area, and the stripping targets at each working position are angled with each other along a straight line. The reason why one stripping target is provided with two working positions is to obtain as many m target stripping points as possible. Because the stripping angle of the stripping target at each working position is limited. The stripping angle of the stripping target is limited, which means that the deflection angle of the stripping target head is limited. Since the target rod can only move forward and backward along a straight line, when a stripping point among the m stripping points and the current stripping target rod are not on the same straight line, stripping cannot be performed by simply relying on the forward and backward movement of the stripping target rod, and the target head must be modified, from the original target head and target rod being on a straight line to the target head deviating from the target rod by an angle. And this angle is also limited, so when the range of stripping of a stripping target is limited, two stripping targets are used.

[0039] Based on the above principles, the present invention designs a method based on H2 + The beam extraction method of high-current superconducting proton cyclotron accelerator is as follows Figure 1 , Figure 2 , Figure 3 As shown, its characteristic is that it includes the following steps:

[0040] Step 1: obtaining K stripping point positions of a stripping target with multiple energies in radial and angular directions; the stripping target is a stripping target with two working positions in the same valley of a high-current superconducting proton cyclotron; the K stripping points are the total stripping points of the stripping target at the two working positions; the K stripping points of multiple energies are stripping points on different energy trajectories; the particle trajectory radius of particles with large energy is relatively large, and the particle trajectory radius of particles with small energy is relatively small;

[0041] Step 2: Use particle tracking program to track H2 at K peeling points + The energy and stripping film azimuth are scanned in two dimensions; the target particle trajectory is determined as follows: the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area, and the stripping points that meet the target particle trajectory selected above are used as n candidate stripping points, and m target stripping points are determined from the n candidate stripping points; the m target stripping points are the stripping points that can enter the central area of ​​the lead-out area entrance;

[0042] Supplementary Note 1

[0043] like Figure 1 As shown in the figure, a total of m upper and lower target stripping points are screened out. The stripping point at the upper position is led out by rotating 2 circles, and the stripping point at the lower position is led out by rotating 1 circle. Their trajectories do not enter the central area or the high-frequency cavity. At the same time, the two trajectories are both in the central area of ​​the switch magnet entrance, and the exits are all gathered at the central point of the switch magnet exit.

[0044] Step 3: using the positions of the m target stripping points as the position of the target stripping target; the position of the target stripping target includes a target radial position and a target angular position;

[0045] Step 4: Calculate the physical parameters of the trajectories of m target peeling points focused on the center point of the focusing element exit.

[0046] Furthermore, the step 2 of determining m target stripping points from n candidate stripping points is specifically as follows:

[0047] 1) A focusing element is arranged in the lead-out area, and the position of the focusing element is the position where the m target stripping point trajectories will pass;

[0048] 2) Select m target stripping points from the n candidate stripping points, whose positions are in the region of the center point of the focusing element entrance and whose speed directions are as close as possible to the direction of the symmetry axis of the focusing element;

[0049] 3) The positions of the m target peeling points are used as the positions of the target peeling targets.

[0050] Furthermore, the physical parameters of the trajectory of the m target peeling points in step 4 are focused on the center point of the focusing element outlet, specifically:

[0051] 1) Calculate the velocity directions of the m target peeling point particles in the center point area of ​​the focusing element entrance: Calculate the velocity directions of the m target peeling point particles before they enter the focusing element based on the fringe field of the main magnet, so that the direction of the particle velocity is approximately perpendicular to the edge line of the center point area of ​​the focusing element entrance;

[0052] 2) Calculate the velocity directions of the m target peeling point particles at the center point of the focusing element exit: superimpose the magnetic field of the focusing element on the edge field of the main magnet, calculate the velocity directions of the m target peeling point particles after entering the focusing element under the condition of the superposition of the two magnetic fields, and adjust the magnetic field of the focusing element according to the velocity directions, so that particles of different energies are focused on the center point of the focusing element exit, and the velocity direction of the particles at the center point of the focusing element exit is the same as the direction of the symmetry axis of the focusing element;

[0053] 3) Saving the adjusted magnetic field of the focusing element;

[0054] 4) determining the physical design of the focusing element according to the adjusted magnetic field of the focusing element;

[0055] Furthermore, the center point area of ​​the process 2) of step two refers to the entrance center point area when the particle trajectories of the m target stripping points can be focused on the exit center point of the focusing element when passing through the focusing element after the focusing element magnetic field and the main magnetic field are superimposed.

[0056] A double-working-position stripping target is characterized in that one stripping target has two working positions in the same valley area, and the two working positions are symmetrical along the center line of the valley area.

[0057] Furthermore, the symmetry along the center line of the valley area means that the stripping target positions at the symmetrical points must satisfy that the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area.

[0058] Furthermore, the m target stripping points are the sum of the stripping points that meet the conditions at the two stripping target working positions, and the conditions are: the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area.

[0059] Furthermore, the target head of the stripping target deviates from the target rod by a set angle as required.

[0060] Supplementary Note 2

[0061] like Figure 2As shown, the target head of the stripping target deviates from the target rod by a set angle as needed. When the stripping point and the target rod are on the same straight line, the target head and the target rod are parallel at 180 degrees. When the stripping point and the target rod are not on the same straight line, the target head deviates from the target rod by an angle.

[0062] Furthermore, the set angle refers to the angle formed by a line connecting the stripping point and the tail of the target rod and the target rod when a stripping point among the m stripping points is not on a straight line of the target rod.

[0063] It should be emphasized that the above specific embodiments are merely explanations of the present invention, and they are not limitations of the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without any creative contribution as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method based on H2 + A high-current superconducting proton cyclotron beam extraction method and a stripping target, characterized in that: The following steps are involved: Step 1: obtaining K stripping point positions of a stripping target with multiple energies in radial and angular directions; the stripping target is a stripping target with two working positions in the same valley of a high-current superconducting proton cyclotron; the K stripping points are the total stripping points of the stripping target at the two working positions; the K stripping points of multiple energies are stripping points on different energy trajectories; the particle trajectory radius of particles with large energy is relatively large, and the particle trajectory radius of particles with small energy is relatively small; Step 2: Use particle tracking program to track H2 at K peeling points + The energy and stripping film azimuth are scanned in two dimensions; the target particle trajectory is determined as follows: the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area, and the stripping points that meet the target particle trajectory selected above are used as n candidate stripping points, and m target stripping points are determined from the n candidate stripping points; the m target stripping points are the stripping points that can enter the central area of ​​the lead-out area entrance; Step 3: using the positions of the m target stripping points as the position of the target stripping target; the position of the target stripping target includes a target radial position and a target angular position; Step 4: Calculate the physical parameters of the trajectories of m target peeling points focused on the center point of the focusing element exit.

2. According to claim 1, a method based on H2 + A high-current superconducting proton cyclotron beam extraction method and a stripping target, characterized in that: The step 2 of determining m target stripping points from n candidate stripping points is specifically as follows: 1) A focusing element is arranged in the lead-out area, and the position of the focusing element is the position where the m target peeling point trajectories are to pass; 2) Select m target stripping points from the n candidate stripping points, whose positions are in the region of the center point of the focusing element entrance and whose speed directions are as close as possible to the direction of the symmetry axis of the focusing element; 3) The positions of the m target peeling points are used as the positions of the target peeling targets.

3. According to claim 1, a method based on H2 + A high-current superconducting proton cyclotron beam extraction method and a stripping target, characterized in that: Step 4 calculates the physical parameters of the trajectory of m target peeling points focused on the center point of the focusing element outlet, specifically: 1) Calculate the velocity directions of the m target peeling point particles in the center point area of ​​the focusing element entrance: Calculate the velocity directions of the m target peeling point particles before they enter the focusing element based on the fringe field of the main magnet, so that the direction of the particle velocity is approximately perpendicular to the edge line of the center point area of ​​the focusing element entrance; 2) Calculate the velocity directions of the m target peeling point particles at the center point of the focusing element exit: superimpose the magnetic field of the focusing element on the edge field of the main magnet, calculate the velocity directions of the m target peeling point particles after entering the focusing element under the condition of the superposition of the two magnetic fields, and adjust the magnetic field of the focusing element according to the velocity directions, so that particles of different energies are focused on the center point of the focusing element exit, and the velocity direction of the particles at the center point of the focusing element exit is the same as the direction of the symmetry axis of the focusing element; 3) Saving the adjusted magnetic field of the focusing element; 4) Determine the physical design of the focusing element based on the adjusted magnetic field of the focusing element.

4. According to claim 1, a method based on H2 + A high-current superconducting proton cyclotron beam extraction method and a stripping target, characterized in that: The center point area of ​​the process 2) of step 2 refers to the entrance center point area when the particle trajectories of the m target stripping points can be focused on the exit center point of the focusing element when passing through the focusing element after the focusing element magnetic field and the main magnetic field are superimposed.

5. A method for use in any one of claims 1 to 4 based on H2 + A high-current superconducting proton cyclotron beam extraction method and a double-working-position stripping target of a stripping target, characterized in that: A stripping target has two working positions in the same valley area, and the two working positions are symmetrical along the center line of the valley area.

6. A dual-working position stripping target according to claim 5, characterized in that: The symmetry on both sides along the center line of the valley area means that the stripping target positions at the symmetrical points must satisfy that the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area.

7. A dual-working position stripping target according to claim 5, characterized in that: The m target stripping points are the sum of the stripping points that meet the conditions at the two stripping target working positions, and the conditions are: the particle trajectory after stripping cannot enter the central area, the particle trajectory after stripping cannot enter the high-frequency area, and the particle trajectory after stripping can enter the lead-out area.

8. The dual-working position stripping target according to claim 5, characterized in that: The target head of the stripping target deviates from the target rod by a set angle as required.

9. A dual-working position stripping target according to claim 8, characterized in that: The set angle refers to the angle formed by the line connecting the stripping point and the tail of the target rod and the target rod when a stripping point among the m stripping points is not on the straight line of the target rod.

Images