Adjustment block for achromatic deflection magnet and adjustment method for achromatic deflection magnet

Abstract

The present invention discloses an adjustment block for a dispersive deflection magnet and an adjustment method for the dispersive deflection magnet. The local adjustment block is arranged in an angle region composed of an upper pole head, a lower pole head, and a central plane, and the region contains a beam inlet and a beam outlet on the central plane; the local adjustment block accurately adjusts the edge field of the dispersive deflection magnet within a vertical and lateral space not exceeding the dispersive deflection magnet; the method comprises: arranging the local adjustment block in the angle region of the dispersive deflection magnet; using a beam measurement device to obtain the angle information of the outgoing beam; if the angle information does not meet the requirements, adjusting the y-direction position of the local adjustment block according to the measurement result; the adjustment rule of the present invention is relatively simple, and is close to realizing the independent adjustment of the beam angle and the lateral position without causing serious mutual influence. Compared with the method of arranging multiple groups of guide magnets downstream of the beam outlet, the structure is compact, and no additional magnets and the accompanying water cooling and power requirements are required.

Description

Technical Field

[0001] The invention belongs to the technical field of beam line achromatic deflection magnets, and in particular relates to an adjustment block for an achromatic deflection magnet and an achromatic deflection magnet adjustment method. Background Art

[0002] The beam is led out of the particle accelerator, and the beam transmission line is laid out between the beam outlet of the particle accelerator and the target point outside the particle accelerator. In the beam transmission line of the particle accelerator, various large deflection magnets may have certain errors, and the achromatic deflection magnet is no exception, such as Figure 5 As shown, the error includes the error between the actual distribution and the theoretical distribution of the magnetic field and the error of the mechanical installation, etc. These errors will cause the emission angle and the emission position of the deflected beam to deviate from the theoretical value to a certain extent.

[0003] like Figure 5 As shown, conventional technology generally uses guide magnets arranged outside the achromatic deflection magnets to adjust the errors of the deflection magnets on the beam transmission line. Through the combination of multiple groups of guide magnets, the beam drawn from the achromatic deflection magnets is deflected at a small angle, or the position of the beam drawn from the achromatic deflection magnets is adjusted. In order to adjust the exit position and exit angle of the beam through the combination of guide magnets on the beam line, the conventional method arranges multiple groups of guide magnets before the upstream inlet outside the achromatic deflection magnets or after the downstream outlet outside the achromatic deflection magnets.

[0004] The difficulty of using guide magnets to adjust the beam transmission line error is that if the guide magnet is placed before the upstream inlet of the achromatic deflection magnet, when the exit angle or position of the downstream exit beam changes, the adjustment effect of adjusting the downstream by the upstream is not good. If the guide magnet is placed after the downstream exit of the achromatic deflection magnet, it will occupy the height space of the downstream beam line. Figure 1a As shown in the figure, when the beam is emitted vertically downward, the irradiation device is installed below the beam line, so the height of the whole equipment is relatively high. If the deflection magnet is arranged after the downstream outlet in the vertical direction, the equipment must be raised, and the plant building will also be raised. In order to avoid raising the plant building, the downstream beam line should be as short as possible, so that the height of the equipment is not too high.

[0005] In summary, when using existing technical means to adjust the error of the achromatic deflection magnet on the beam transmission line, the difficulty lies in: on the one hand, placing the guide magnet before the upstream entrance of the achromatic deflection magnet has a poor error adjustment effect, so the guide magnet is generally arranged after the downstream exit; on the other hand, if the guide magnet is placed after the downstream exit, the equipment floor height will be too high. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides an adjustment block for an achromatic deflection magnet and an achromatic deflection magnet adjustment method, aiming to solve the problem that the prior art that the deflection magnet is arranged before the downstream outlet of the achromatic deflection magnet will make the equipment layer height too high.

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

[0008] A local adjustment block for accurately adjusting the edge field of an achromatic deflection magnet, the local adjustment block is based on an achromatic deflection magnet with a local adjustment block, the achromatic deflection magnet comprises an outer iron yoke, an excitation coil or a permanent magnet block, a pole head, and a local adjustment block; the outer iron yoke and the pole head are connected together, and the outer iron yoke is composed of an upper iron yoke, a lower iron yoke and a side iron yoke; the excitation coil or the permanent magnet block is divided into two groups, which are respectively installed around the upper and lower pole heads, and the excitation coil is composed of a normal conductive copper coil, a superconducting coil, etc.; the pole head is divided into a symmetrical upper pole head and a lower pole head, and the upper pole head and the lower pole head are respectively connected to the upper iron yoke and the lower iron yoke; the pole head has a pole face, and the center plane is between the two pole faces, and the excitation coil or the permanent magnet block excites the deflection magnetic field in the center plane air gap between the upper and lower pole heads;

[0009] Its characteristics are: the local adjustment block is arranged in an angle area formed by the upper pole head, the lower pole head, and the central plane between the upper and lower pole heads, and the angle area contains the beam entrance and the beam exit on the central plane; the local adjustment block accurately adjusts the fringe field of the achromatic deflection magnet within the vertical space and the lateral space not exceeding the achromatic deflection magnet, and the fringe field is the fringe field at the beam entrance and the beam exit of the central plane; the local adjustment block is composed of soft magnetic material.

[0010] Furthermore, the local adjustment block is approximately rectangular, and its upper and left halves form a right-angled magnetic shielding interlayer; the beam enters the beam inlet of the achromatic deflection magnet from the right side of the right-angled magnetic shielding interlayer along the horizontal direction, rotates 270° inside the achromatic deflection magnet, flows out from the beam outlet of the achromatic deflection magnet, and exits from the lower edge of the right-angled magnetic shielding interlayer along the vertical direction.

[0011] Furthermore, the vertical space and the lateral space not exceeding the achromatic deflection magnet means that the height and the width of the local adjustment block do not exceed the height space and the width space of the outer iron yoke of the achromatic deflection magnet.

[0012] Furthermore, when the height of the achromatic deflection magnet is 1400 mm and the width is 1400 mm, the length of the local adjustment block is 540 mm and the height is 340 mm.

[0013] Furthermore, when the length of the local adjustment block is 540 mm and the height is 340 mm, the air gap width within the interlayer of the rectangular magnetic shielding interlayer of the local adjustment block is 60 mm, the air gap depth is 180 mm, and the magnetic shielding thickness on both sides of the interlayer is 35 mm each.

[0014] Furthermore, the initial distance between the upper edge of the local adjustment block and the beam trajectory point on the beam outlet of the achromatic deflection magnet is 150 mm.

[0015] Furthermore, the initial distance between the left line of the local adjustment block and the beam trajectory point on the beam inlet of the achromatic deflection magnet is 150 mm.

[0016] A method for adjusting the fringe field of an achromatic deflection magnet is characterized by comprising the following steps:

[0017] Step 1: Arrange a local adjustment block in the angle region of the achromatic deflection magnet;

[0018] The angle region is an angle region formed by the upper pole head, the lower pole head, and the central plane, the angle region contains a beam inlet and a beam outlet on the central plane, and the height and width of the local adjustment block do not exceed the height space and width space of the outer iron yoke of the achromatic deflection magnet;

[0019] Step 2: Using a beam measuring device to obtain angle information of the outgoing beam;

[0020] Step 2: Check whether the angle information meets the requirements. If it meets the requirements, proceed to step 3. If it does not meet the requirements, proceed to step 7.

[0021] Step 3: using a beam measuring device to obtain lateral position information of the outgoing beam;

[0022] Step 4: Check whether the horizontal position information meets the requirements. If it meets the requirements, the adjustment is completed. If it does not meet the requirements, proceed to step 5.

[0023] Step 5: Adjust the x-direction position of the local adjustment block according to the measurement results;

[0024] Step 6: Check whether the x-position meets the requirements. If not, return to step 5. If it meets the requirements, end the adjustment.

[0025] Step 7: Adjust the y-direction position of the local adjustment block according to the measurement results;

[0026] Step 8: Check whether the Y-position meets the requirements. If not, return to step 7. If it meets the requirements, end the adjustment.

[0027] Advantages and effects of the present invention

[0028] 1. The adjustment device and method can adjust the angle and position of the outgoing beam of the achromatic deflection magnet. The adjustment rule within the adjustment range is relatively simple, and the independent adjustment of the beam angle and the lateral position is nearly achieved without causing serious mutual influence. The adjustment range meets the application requirements of the accelerator.

[0029] 2. Compared with the method of arranging multiple sets of guide magnets downstream of the beam outlet, the adjustment device and method proposed in the present invention are compact in structure and do not require additional magnets and the accompanying water cooling and power requirements. They are suitable for compact beam line arrangements, especially for beam lines that emit vertically downward, and the adjustment device and method can greatly reduce the requirements for equipment floor height.

[0030] 3. Compared with the method of arranging multiple sets of guide magnets upstream of the beam inlet, the regulating device and method proposed by the present invention has a larger regulating range, and the regulating variables are relatively independent, and the regularity within the regulating range is simple. It also has the advantages of compact structure, no need for additional magnets and their accompanying water cooling and power requirements.

[0031] 4. The adjustment device and method have a large adjustment range. Even if the achromatic deflection magnet itself has a large error with the theoretical value, it is still within the adjustment capability of the adjustment device and method. Therefore, the adjustment device and method can also reduce the design difficulty of the achromatic deflection magnet and the process accuracy requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1a This is an appearance diagram of the application effect of the achromatic deflection magnet with a local adjustment block of the present invention;

[0033] Figure 1b It is a cross-sectional view of the application effect of the achromatic deflection magnet with a local adjustment block of the present invention;

[0034] Figure 2a This is a first viewing angle of the appearance of the achromatic deflection magnet with a local adjustment block of the present invention;

[0035] Figure 2b The second viewing angle of the appearance diagram of the achromatic deflection magnet with a local adjustment block of the present invention;

[0036] Figure 3 It is a cross-sectional view of the achromatic deflection magnet with a local adjustment block of the present invention;

[0037] Figure 4a The first viewing angle of the local adjustment block of the present invention;

[0038] Figure 4b The second viewing angle of the local adjustment block of the present invention;

[0039] Figure 5 This is a schematic diagram of adjusting the beam exit angle and exit position by the guide magnet before improvement;

[0040] Figure 6 It is a schematic diagram of the theoretical magnetic field and the actual magnetic field when there is no local adjustment block before improvement;

[0041] Figure 7 It is a schematic diagram of the theoretical magnetic field and the actual magnetic field when the improved local adjustment block is provided;

[0042] Figure 8 This is the effect of adjusting the position of the local adjustment block along the x direction;

[0043] Fig. 9 This is the effect of adjusting the position of the local adjustment block along the y direction;

[0044] Fig.10 Flowchart for adjusting the beam exit angle and lateral position of the local adjustment block.

[0045] In the figure, 1: outer iron yoke; 2: local adjustment block; 2-1: right-angled magnetic shielding interlayer; 2-2: magnetic shielding walls on both sides of the interlayer; 3: excitation coil; 4: pole head; 4-1: upper pole head; 4-2: lower pole head; 5: center plane; 5-1: beam entrance; 5-2: beam exit. DETAILED DESCRIPTION

[0046] Design principle of the present invention

[0047] 1. Innovation of the present invention: The innovation lies in replacing the "combined guide magnet (the combined guide magnet is two guide magnets placed before the upstream inlet or after the downstream outlet respectively, and the two guide magnets before the upstream inlet or after the downstream outlet can adjust the position and angle of the beam)" of the prior art with a "local adjustment block" made of soft magnetic material. The difference from the prior art is that: first, the "local adjustment block" of the present invention does not occupy additional space (the additional space is the longitudinal space and transverse space occupied outside the achromatic deflection magnet), but only uses the original "angle area" of the achromatic deflection magnet and does not exceed the original area. Therefore, the height of the equipment will not be too high, while the guide magnet of the prior art must occupy additional height space: in order to achieve a significant adjustment effect, the guide magnet cloth of the prior art must be arranged in the vertical direction along the beam outlet. Since the height of the guide magnet is nearly one-third of the entire achromatic deflection magnet, the height of the entire equipment will also increase; second, the "local adjustment block" of the present invention is a soft magnetic material, while the guide magnet of the prior art is an electromagnet. The electromagnet actively generates a magnetic field, while the soft magnetic material itself does not generate a magnetic field, but only changes the distribution of the magnetic field. Since the electromagnet itself has a magnetic field, the magnetic field and the magnetic field of the achromatic deflection magnet excitation affect each other, making the adjustment of the fringe field more complicated; the soft magnetic material of the present invention does not generate a magnetic field itself, but can adjust the position and angle of the beam only through its position in the x and y directions, and the adjustment method is much simpler.

[0048] 2. Several key points of the present invention: First, the design of the local adjustment block interlayer. The local adjustment block interlayer is used for beam passage. The design gap is 60mm in order to allow effective beam passage and prevent the shielding walls on both sides from being too close to the excitation coil. If the interlayer gap is too narrow, part of the beam will be blocked. If the gap is too wide, the shielding wall will inevitably be pushed to both sides, making the shielding wall too close to the excitation coil. Second, the design of the magnetic shielding wall of the local adjustment block: the magnetic shielding walls on both sides of the gap of the local adjustment block cannot be too thin, otherwise the shielding effect cannot be achieved. They cannot be too thick either, because the outside of the magnetic shielding wall is the excitation coil. If the magnetic shielding wall is too thick, it will be too close to the excitation coil. If the distance is too close, it will affect the main magnetic field of the achromatic deflection magnet. Therefore, the thickness of the shielding wall is 35mm. Third, the length, width, distance from the upper edge line to the beam outlet, distance from the left edge line to the beam entrance of the local adjustment block, as well as the width of the right-angle interlayer gap and the depth of the gap jointly determine the adjustment effect of the local adjustment block on the magnetic field distribution of the edge field, that is, the adjustment effect on the beam.

[0049] In short, the design of the local adjustment block must meet several conditions: layout position: the local adjustment block should be arranged within the vertical space and width space that does not exceed the achromatic deflection magnet, material: soft magnetic material; the width of the right-angle interlayer gap is 60mm and the depth is 180mm; the length, width, distance from the upper edge line to the beam outlet, and the distance from the left edge line to the beam entrance of the local adjustment block must meet the requirements to achieve the ideal effect. If any of these conditions are missing, the expected effect cannot be achieved.

[0050] Based on the above invention principle, the present invention designs a local adjustment block for accurately adjusting the edge field of the achromatic deflection magnet, such as Figure 1a , Figure 1b , Figure 2a , Figure 2b , Figure 3 , Figure 5 As shown, the local adjustment block is based on an achromatic deflection magnet with a local adjustment block, and the achromatic deflection magnet includes an outer iron yoke 1, an excitation coil 3 or a permanent magnet block, a pole head 4, and a local adjustment block 2; the outer iron yoke 1 and the pole head 4 are connected together, and the outer iron yoke is composed of an upper iron yoke, a lower iron yoke and a side iron yoke; the excitation coil 3 or the permanent magnet block is divided into two groups, which are respectively installed around the upper and lower pole heads, and the excitation coil 3 is composed of a normal conductive copper coil and a superconducting coil; the pole head is divided into a symmetrical upper pole head 4-1 and a lower pole head 4-2, and the upper pole head 4-1 and the lower pole head 4-2 are respectively connected to the upper iron yoke and the lower iron yoke; the pole head has a pole face, and a center plane 5 is between the two pole faces. The excitation coil 3 or the permanent magnet block excites the deflection magnetic field in the center plane air gap between the upper and lower pole heads;

[0051] Its characteristics are: Figure 3 As shown, the local adjustment block 2 is arranged in an angle area formed by the upper pole head 4-1, the lower pole head 4-2, and the central plane 5 between the upper and lower pole heads, and the angle area contains a beam inlet 5-1 and a beam outlet 5-2 on the central plane 5; the local adjustment block 2 accurately adjusts the fringe field of the achromatic deflection magnet within the vertical space and lateral space not exceeding the achromatic deflection magnet, and the fringe field is the fringe field at the beam inlet 5-1 and the beam outlet 5-2 at the central plane 5; the local adjustment block 2 is composed of soft magnetic material.

[0052] like Figure 3 , Figure 4a , 4b As shown, the local adjustment block is approximately rectangular, and its upper and left halves form a rectangular magnetic shielding interlayer 2-1; the beam enters the beam inlet 5-1 of the achromatic deflection magnet from the right side of the rectangular magnetic shielding interlayer 2-1 along the horizontal direction, rotates 270° inside the achromatic deflection magnet, flows out from the beam outlet 5-2 of the achromatic deflection magnet, and exits from the lower edge of the rectangular magnetic shielding interlayer 2-1 along the vertical direction.

[0053] like Figure 3 As shown, the vertical space and lateral space that do not exceed the achromatic deflection magnet means that the height and width of the local adjustment block do not exceed the height space and width space of the outer iron yoke of the achromatic deflection magnet.

[0054] When the height of the achromatic deflection magnet is 1400 mm and the width is 1400 mm, the length of the local adjustment block is 540 mm and the height is 340 mm.

[0055] When the length of the local adjustment block is 540 mm and the height is 340 mm, the air gap width in the right-angle magnetic shielding interlayer of the local adjustment block is 60 mm, the air gap depth is 180 mm, and the magnetic shielding thickness on both sides of the interlayer is 35 mm respectively.

[0056] like Figure 3 As shown, the initial distance between the upper edge of the local adjustment block 2 and the beam trajectory point on the achromatic deflection magnet beam outlet 5-2 is 150 mm.

[0057] Furthermore, the initial distance between the left line of the local adjustment block 2 and the beam trajectory point on the achromatic deflection magnet beam inlet 5 - 1 is 150 mm.

[0058] Supplementary explanation: The above two initial distances of 150mm refer to the distance of 150mm before the local adjustment block is adjusted. During the adjustment process, this distance changes, and the position and angle of the beam are adjusted by the change of this distance.

[0059] A method for adjusting the fringe field of an achromatic deflection magnet Fig.10 As shown, its characteristics are that it includes the following steps:

[0060] Step 1: Arrange a local adjustment block in the angle region of the achromatic deflection magnet;

[0061] The angle region is an angle region formed by the upper pole head, the lower pole head, and the central plane, the angle region contains a beam inlet and a beam outlet on the central plane, and the height and width of the local adjustment block do not exceed the height space and width space of the outer iron yoke of the achromatic deflection magnet;

[0062] Step 2: Using a beam measuring device to obtain angle information of the outgoing beam;

[0063] Step 2: Check whether the angle information meets the requirements. If it meets the requirements, proceed to step 3. If it does not meet the requirements, proceed to step 7.

[0064] Step 3: using a beam measuring device to obtain lateral position information of the outgoing beam;

[0065] Step 4: Check whether the horizontal position information meets the requirements. If it meets the requirements, the adjustment is completed. If it does not meet the requirements, proceed to step 5.

[0066] Step 5: Adjust the x-direction position of the local adjustment block according to the measurement results;

[0067] Step 6: Check whether the x-position meets the requirements. If not, return to step 5. If it meets the requirements, end the adjustment.

[0068] Step 7: Adjust the y-direction position of the local adjustment block according to the measurement results;

[0069] Step 8: Check whether the Y-position meets the requirements. If not, return to step 7. If it meets the requirements, end the adjustment.

[0070] Example 1: Comparison of fringe field curves before and after improvement

[0071] 1. The edge field curve before improvement: Figure 6 As shown in the figure, for the achromatic deflection magnet, the edge of the pole head is a right angle. Theoretically, the edge of the pole head is the boundary of the magnetic field, there is a magnetic field inside the pole head, and there is no magnetic field outside the pole head. However, in reality, due to the leakage field of the actual magnet, the magnetic field at the edge of the pole head will not directly change from a magnetic field to a non-magnetic field, but as shown in the figure. Figure 6 There is a transition region as shown, which is called the fringe field region of the magnet. Figure 6 The figure shows the schematic diagram of the theoretical magnetic field and the actual magnetic field when the original design does not have a local adjustment block. The vertical axis is the magnetic field value along the reference line, which is consistent with the direction in which the beam is incident on the magnet.

[0072] 2. Improved edge field curve: Figure 7 As shown, next consider the case where there is a local adjustment block. When there is a local adjustment block outside the pole head along the reference line direction, the beam will first pass through the local adjustment block. At this time, the local adjustment block has a magnetic shielding effect, so that the inside of the local adjustment block is close to being free of magnetic field, and the shape of the fringe field is changed. By adjusting the relative position of the local adjustment block and the achromatic deflection magnet, the shape of the fringe field can be precisely controlled. The fringe field can also cause the beam to deflect. When the beam is incident, the magnetic field begins to deflect only when the beam leaves the range of the local adjustment block. In other words, during the incident process of the beam, adjusting the relative position of the local adjustment block and the achromatic deflection magnet can control the position where the beam begins to deflect.

[0073] For the beam emission process, the position where the beam ends its deflection can be controlled. Figure 7 In the coordinate system shown, the x-direction position of the local adjustment block determines the position where the beam starts to deflect during the incident process, and the y-direction position of the local adjustment block determines the position where the beam ends to deflect during the exit process.

[0074] Embodiment 2: Regulation principle and regulation method

[0075] The effect of adjusting the local adjustment block along the x direction is as follows: Figure 8 The local adjustment block is shown along the x direction ( Figure 8 The right figure in the figure is an enlarged view of the circle in the left figure), which are the trajectories of the same beam with ±10% energy dispersion when the reference position x=0mm, when x is adjusted to x=-10mm in the negative direction, and when x is adjusted to x=+10mm in the positive direction. It can be seen from the figure that compared with the beam at the reference position x=0mm, the beam at x=±10mm can adjust the lateral position offset of the exit beam by about ±4.5mm, and the angle change is very small, less than 0.2°.

[0076] The effect of adjusting the local adjustment block along the y direction is as follows: Fig. 9 The local adjustment block is shown along the y direction ( Fig. 9 The right figure in the figure is an enlarged view of the circle in the left figure), which are the trajectories of the same beam with ±10% energy divergence when the reference position is y=0mm, when y is adjusted to y=-10mm in the negative direction, and when y is adjusted to y=+10mm in the positive direction. It can be seen from the figure that compared with the beam at the reference position y=0mm, the beam at y=±10mm can adjust the angle change of the exit beam by about ±1.3°. All beams basically pass through the same focusing point, so the lateral position offset of its downstream is due to the angle change.

[0077] Summary of adjustment methods: Figure 7-8When the local adjustment block is adjusted along the x direction, it will basically only cause the change of the lateral position of the outgoing beam, and the effect on the angle is very small. When the local adjustment block is adjusted along the y direction, it will basically only cause the change of the angle of the outgoing beam, and it can still ensure that it passes through the same point, but in the downstream, due to the change of the beam angle, there will be a certain lateral position change.

[0078] This adjustment method has a relatively simple change rule when adjusting the x and y directions separately, and nearly realizes the independent adjustment of the beam angle and the lateral position without causing serious mutual influence. According to the adjustment method of the present invention, the angle and lateral position of the output beam passing through the achromatic deflection magnet can be conveniently adjusted.

[0079] 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 local adjustment block for accurately adjusting the edge field of an achromatic deflection magnet, the local adjustment block is based on an achromatic deflection magnet with a local adjustment block, the achromatic deflection magnet comprises an outer iron yoke, an excitation coil or a permanent magnet block, a pole head, and a local adjustment block; the outer iron yoke and the pole head are connected together, and the outer iron yoke is composed of an upper iron yoke, a lower iron yoke and a side iron yoke; the excitation coil or the permanent magnet block is divided into two groups, which are respectively installed around the upper and lower pole heads, and the excitation coil is composed of a normal conductive copper coil, a superconducting coil, etc.; the pole head is divided into a symmetrical upper pole head and a lower pole head, and the upper pole head and the lower pole head are respectively connected to the upper iron yoke and the lower iron yoke; the pole head has a pole face, and the center plane is between the two pole faces, and the excitation coil or the permanent magnet block excites the deflection magnetic field in the center plane air gap between the upper and lower pole heads; Features: The local adjustment block is arranged in an angle region formed by the upper pole head, the lower pole head, and the central plane, and the angle region contains a beam inlet and a beam outlet on the central plane; the local adjustment block accurately adjusts the fringe field of the achromatic deflection magnet within a vertical space and a lateral space not exceeding the achromatic deflection magnet, and the fringe field is the fringe field at the beam inlet and the beam outlet of the central plane; the local adjustment block is made of soft magnetic material; The local adjustment block is approximately rectangular, and its upper and left halves form a right-angled magnetic shielding sandwich; the beam enters the beam inlet of the achromatic deflection magnet from the right side of the right-angled magnetic shielding sandwich along the horizontal direction, rotates 270° in the achromatic deflection magnet, flows out from the beam outlet of the achromatic deflection magnet, and exits from the lower edge of the right-angled magnetic shielding sandwich along the vertical direction; The vertical space and the lateral space that do not exceed the achromatic deflection magnet means that the height and the width of the local adjustment block do not exceed the height space and the width space of the outer iron yoke of the achromatic deflection magnet.

2. A local adjustment block for accurately adjusting the fringe field of an achromatic deflection magnet according to claim 1, characterized in that: When the height of the achromatic deflection magnet is 1400 mm and the width is 1400 mm, the length of the local adjustment block is 540 mm and the height is 340 mm.

3. A local adjustment block for accurately adjusting the fringe field of an achromatic deflection magnet according to claim 2, characterized in that: When the length of the local adjustment block is 540 mm and the height is 340 mm, the air gap width in the right-angle magnetic shielding interlayer of the local adjustment block is 60 mm, the air gap depth is 180 mm, and the magnetic shielding thickness on both sides of the interlayer is 35 mm respectively.

4. A local adjustment block for accurately adjusting the fringe field of an achromatic deflection magnet according to claim 1, characterized in that: The initial distance between the upper edge of the local adjustment block and the beam trajectory point on the beam outlet of the achromatic deflection magnet is 150 mm.

5. A local adjustment block for accurately adjusting the fringe field of an achromatic deflection magnet according to claim 1, characterized in that: The initial distance between the left line of the local adjustment block and the beam trajectory point on the beam entrance of the achromatic deflection magnet is 150 mm.

6. A method for adjusting the fringe field of an achromatic deflection magnet based on a local adjustment block for accurately adjusting the fringe field of an achromatic deflection magnet according to any one of claims 1 to 5, characterized in that , including the following steps: Step 1: Arrange a local adjustment block in the angle region of the achromatic deflection magnet; The angle region is an angle region formed by the upper pole head, the lower pole head, and the central plane, the angle region contains a beam inlet and a beam outlet on the central plane, and the height and width of the local adjustment block do not exceed the height space and width space of the outer iron yoke of the achromatic deflection magnet; Step 2: Using a beam measuring device to obtain angle information of the outgoing beam; Step 2: Check whether the angle information meets the requirements. If it meets the requirements, proceed to step 3. If it does not meet the requirements, proceed to step 7. Step 3: using a beam measuring device to obtain lateral position information of the outgoing beam; Step 4: Check whether the horizontal position information meets the requirements. If it meets the requirements, the adjustment is completed. If it does not meet the requirements, proceed to step 5. Step 5: Adjust the x-direction position of the local adjustment block according to the measurement results; Step 6: Check whether the x-axis position meets the requirements. If not, return to step 5. If it meets the requirements, end the adjustment. Step 7: Adjust the y-direction position of the local adjustment block according to the measurement results; Step 8: Check whether the Y-position meets the requirements. If not, return to step 7. If it meets the requirements, end the adjustment.

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