A scanning profile measurement target head and apparatus suitable for use with low energy high current beams

Abstract

The application belongs to the technical field of accelerator beam diagnosis, and relates to a scanning profile measurement target head and device suitable for a low-energy high-current beam, which comprises a slit part, a bias part, a collection part and a fixing support. The slit part is provided with a composite plate with a slit in the middle, which is used for blocking the beam and allowing only the beam in the slit to pass. The bias part is provided with a cutout corresponding to the slit in the middle, which is used for suppressing secondary electrons through high voltage. The collection part is a V-shaped inverted cone, the opening of which faces the bias part, and is used for collecting electrons passing through the slit. The fixing support is used for sequentially fixing the slit part, the bias part and the collection part according to the propagation direction of the beam. The device meets the frequent and accurate profile measurement requirements of the high-current accelerator in the medium and low energy region.

Description

Technical Field

[0001] This invention relates to a scanning profile measurement target and device suitable for low-energy high-current beams, belonging to the field of accelerator beam diagnostic technology. Background Technology

[0002] Beam diagnostics is a crucial subsystem in proton and heavy ion accelerators. It involves measuring and monitoring various parameters such as beam energy, flux, and emittance, ensuring parameter matching and stable operation of the beam across different sections before and after the accelerator. Beam profile is a key parameter affecting beam quality. For example, in the medium energy transfer section (MEBT) of a linear accelerator, physicists need to strictly control the profile dimensions to reduce beam loss in the downstream acceleration section. In a ring synchrotron, profile measurements can be extended to diagnose parameters such as emittance, dispersion, and chromaticity, and can also assist in research on injection matching, lateral cooling, and brightness enhancement.

[0003] Based on a review of domestic and international literature and combined with experience in beam diagnostic engineering, common profile measurement methods on proton and heavy ion accelerators can be categorized according to whether the beam is blocked:

[0004] (1) Interception measurements include fluorescent targets (VS), single-wire scanners (WS), multi-wire and harp detectors, etc. The principle of VS detectors is to directly bombard a ceramic or other target with a beam, and use the generated fluorescence signal to obtain profile information. Its advantage is that it can perform two-dimensional and intuitive measurements. Its disadvantage is that under strong beam conditions, the target is easily damaged by temperature rise or stress. Single-wire and multi-wire probes bombard a metal wire with a beam, and use the generated secondary electron signal to measure the profile. The advantage is that the temperature rise is smaller than that of VS. However, because the wire is too thin (the diameter is usually 30-100μm) and has poor mechanical strength, it is easy to break, resulting in frequent vacuum breaking for maintenance and replacement.

[0005] (2) Non-interceptor measurements, such as residual gas ionization profile probes (IPM) and beam-induced fluorescence profile probes (BIF). These probes are based on the physical mechanism of ionization or excitation between the beam and the residual gas. Their advantage is that non-interceptor measurements can be used under high-current beam conditions. The disadvantages are that indirect measurements have certain errors, require calibration and excitation with interceptor probes, and have relatively low signal sensitivity. For example, BIF probes usually require local gas filling to enhance the signal.

[0006] In the low and medium energy ranges of future high-current accelerators, especially in the medium energy transport section (MEBT) of superconducting linear accelerators, lateral profile and emittance measurements are performed more frequently. The measured profile dimensions are used to optimize the optical setup, ensuring good lateral matching between the MEBT and the downstream acceleration section. This reduces the beam loss in the superconducting section to an acceptable threshold or below (typically 1 W / m or below).

[0007] To address the above requirements, non-interceptor IPM or BIF probes have relatively large measurement errors, require calibration, and have weak signals; interceptor fluorescent targets cannot cope with strong current beam conditions, are prone to stress cracking or high-temperature melting, and suffer from problems such as luminescence attenuation and halo; interceptor single-filament or multi-filament targets have slightly better temperature rise issues than fluorescent targets, but due to resolution requirements, their filament diameter is usually small (100μm and below), resulting in lower mechanical strength and poor stability. Summary of the Invention

[0008] To address this problem, the present invention aims to provide a scanning profile measurement target and device suitable for low-energy high-current beams, so as to meet the needs of high-current accelerators for frequent and accurate profile measurement in the low-to-medium energy region.

[0009] To achieve the objective, the present invention proposes the following technical solution: a scanning profile measurement target head suitable for low-energy high-current beams, comprising: a slit section, a bias section, a collecting section, and a fixed bracket; the slit section has a composite plate with a slit in the middle for blocking the beam current, allowing only the beam current within the slit to pass through; the bias section has a cut in the middle corresponding to the slit for suppressing secondary electrons with high voltage; the collecting section is a V-shaped inverted cone with its opening facing the bias section for collecting electrons passing through the slit; the fixed bracket is used to fix the slit section, bias section, and collecting section sequentially according to the beam propagation direction.

[0010] Furthermore, the slit portion includes two metal plates. A slit is machined in the center of the first metal plate using a wire cutting process. A recessed cooling water channel is provided in the second metal plate. The first and second metal plates are welded into a whole using high-temperature explosive welding.

[0011] Furthermore, the first metal plate is a tantalum layer, the second metal plate is a copper layer, the inner tangent section of the slit in the tantalum layer is a right angle, and the inner tangent section of the slit in the copper layer is an oblique angle; the cut section of the biasing part is an oblique angle, and the oblique angle of the cut section is not less than the oblique angle of the inner tangent section of the slit in the copper layer.

[0012] Furthermore, several serrations are provided on the inner surface of the V-shaped inverted cone to increase the probability of secondary electrons returning within the cone.

[0013] Furthermore, the width of the opening of the V-shaped inverted cone perpendicular to the slit direction is not less than the width of the cut of the biasing part; the width of the opening of the V-shaped inverted cone parallel to the slit direction is not less than the length of the cut of the biasing part; and the cone base angle is not less than the inclination angle of the cut section of the biasing part.

[0014] The present invention also discloses a scanning profile measurement device suitable for low-energy high-current beams, comprising: a measurement target head, a motion module, and a data processing module; the measurement target head adopts a scanning profile measurement target head suitable for low-energy high-current beams as described in any one of the present invention; the motion module is used to drive the measurement target head to perform line-by-line scanning; the data processing module is used to analyze and process the data collected by the measurement target head.

[0015] Furthermore, the motion module includes a housing, a servo motor, a coupling, a lead screw, a transmission rod, a first sealing flange, a second sealing flange, a limit switch, a photoelectric switch, and a steel ruler. The housing is used to fix the servo motor, which is sequentially connected to the coupling, the lead screw, and the transmission rod, and drives the transmission rod to reciprocate. The end of the transmission rod is connected to the first sealing flange, which is fixedly connected to the measuring target head. The second sealing flange is located at the connection between the lead screw and the transmission rod, and is used to fix the lead screw and the transmission rod to the housing. The limit switch and the photoelectric switch are used to control the position of the measuring target head by limiting the position of the transmission rod. The steel ruler is combined with the absolute position encoder on the servo motor to accurately calculate the displacement of the transmission rod.

[0016] Furthermore, the motion module also includes a cooling water pipe, a water pipe connector, a corrugated pipe, and a connecting pipe. The cooling water pipe includes two pipes, which are respectively connected to one end of the corrugated pipe through the water pipe connector. The transmission rod is a hollow structure with two connecting pipes installed inside. One end of the two connecting pipes is connected to the other end of the corrugated pipe, and the other end of the two connecting pipes is connected to the input and output ends of the cooling water circuit in the second layer of metal plate through through holes on the first sealing flange, forming a cooling circuit.

[0017] Furthermore, there are two measuring targets, and the slits of the two measuring targets are at a 45-degree angle to the movement direction of the motion module. When the motion module drives the test target to move in a straight line, a single scan can perform cross-sectional measurements in both the horizontal and vertical directions.

[0018] Furthermore, the data processing module includes an IV impedance amplifier, an analog-to-digital acquisition card (ADC), a programmable logic processor (FPGA), and an embedded ARM and EPICS. The data acquired by the measurement target is amplified by the IV impedance amplifier, and the amplified data is converted into a digital signal by the ADC. The FPGA processes the digital signal, and the embedded ARM and EPICS are used to store the digital signal and its processing results.

[0019] The present invention has the following advantages due to the adoption of the above technical solutions:

[0020] 1. The measuring target in this invention can significantly increase the accuracy of current intensity measurement, effectively suppress the escape of low-energy electrons, and improve the power limit that the detector can withstand, up to 20kW pulse beam, which can meet the profile measurement application of the low-energy section of high-current accelerators.

[0021] 2. In this invention, the motion module uses a servo motor with an absolute position encoder, which has very high overall displacement accuracy, reaching the level of hundreds of micrometers. The motion module is equipped with limit switches and photoelectric switches, and multiple redundancy considerations are taken for motion safety to ensure that even if the coupling is loose, the probe will not fall due to the pressure difference between vacuum and atmospheric pressure.

[0022] 3. In this invention, the cooling circuit, while achieving a water-cooling path, ensures a leakage rate requirement of 1E-10mbar*L / s in high vacuum and passes a water pressure test of 0.8kg.

[0023] 4. The data processing module has high sensitivity for current intensity measurement, can recognize signals as low as 10 nA, and has a high dynamic range, with a dynamic range of approximately 6 orders of magnitude 1E6. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a scanning profile measurement target head suitable for low-energy high-current beams according to one embodiment of the present invention. Figure 1 (a) is a front view of the measuring target. Figure 1 (b) is a top view of the measuring target. Figure 1 (c) is a diagram of the internal structure of the measuring target. Figure 1 (d) is a bottom view of the measuring target head;

[0025] Figure 2 This is a schematic diagram of the slit portion in one embodiment of the present invention. Figure 2 (a) is a schematic diagram of the structure of the first metal plate. Figure 2 (b) is a structural schematic diagram of the second metal plate;

[0026] Figure 3This is a schematic diagram of the biasing section in one embodiment of the present invention. Figure 3 (a) is a schematic diagram of the front of the bias section. Figure 3 (b) is a schematic diagram of the back side of the bias section;

[0027] Figure 4 This is a schematic diagram of the collecting section in one embodiment of the present invention. Figure 4 (a) is a structural diagram of the front of the collecting section. Figure 4 (b) is a structural diagram of the back of the collecting section;

[0028] Figure 5 This is a schematic diagram of the structure of a scanning profile measurement device applicable to low-energy high-current beams in one embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the motion module in one embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the data processing module in one embodiment of the present invention;

[0031] Figure 8 This is an equipotential line diagram of the electric field of the bias section in one embodiment of the present invention;

[0032] Figure 9 This is a curve showing the beam time versus temperature obtained through temperature simulation experiments using the ANSYS Fluent module. Figure 9 (a) is a curve showing the change of beam time with temperature obtained by the device in this invention; Figure 9 (b) is a graph showing the change of beam time with temperature obtained by the prior art device;

[0033] Figure 10 This is a schematic diagram of the horizontal profile measurement results according to an embodiment of the present invention;

[0034] Figure 11 This is a schematic diagram of a double slit measurement in both horizontal and vertical directions according to an embodiment of the present invention.

[0035] Figure label:

[0036] 1-Measuring target head; 11-Slit section; 111-Slit; 112-First metal plate; 113-Second metal plate; 114-Cooling water channel; 12-Bias section; 121-Slit; 13-Collection section; 131-V-shaped inverted cone; 132-Sawtooth; 14-Fixed bracket; 2-Motion module; 21-Housing; 22-Servo motor; 23-Coupling; 24-Lead screw; 25-Transmission rod; 26-First sealing flange; 27-Second sealing flange; 28-Limit switch; 29-Photoelectric switch; 210-Steel ruler; 211-Supporting meniscus; 212-Lifting ring; 213-Cooling water pipe; 214-Water pipe connector; 215-Corrugated pipe; 216-Connecting pipe; 3-Data processing module. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for a better understanding of the present invention and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] To address the problems in existing technologies, such as large relative measurement errors, the need for calibration, weak signals, inability to cope with high-current beam conditions, easy target stress fracture or high-temperature melting, light emission attenuation and halo, and poor stability due to low mechanical strength, this invention proposes a scanning profile measurement target head 1 and device suitable for low-energy high-current beams. The measurement target head 1 includes a slit section 11, a bias section 12, a collection section 13, and a fixing bracket 14. It can significantly increase the accuracy of current intensity measurement, effectively suppress low-energy electron escape, and improve the power limit that the detector can withstand (20kW pulse beam), which can meet the profile measurement application in the low-energy section of high-current accelerators. In addition to the measuring target 1, the measuring device also includes a motion module 2 and a data processing module 3. The motion module 2 is composed of a servo motor 22 with an absolute position encoder and corresponding mechanical devices, which has very high displacement accuracy, reaching the level of hundreds of micrometers. The data processing module 3 is a highly integrated system of an analog-to-digital acquisition card (ADC), a programmable logic processor (FPGA), and an embedded ARM (Acorn RISC Machine) and EPICS (Experimental Physics and Industrial Control System). It has high sensitivity for current intensity measurement, can recognize signals as low as 10 nA, and has a high dynamic range, with a dynamic range of approximately 6 orders of magnitude 1E6.

[0039] Example 1

[0040] This embodiment discloses a scanning profile measurement target head 1 suitable for low-energy high-current beams, such as... Figure 1 As shown, it includes: a slit portion 11, a biasing portion 12, a collecting portion 13, and a fixing bracket 14;

[0041] The slit section 11 has a composite plate in the middle of it, which is used to block the beam and only allow the beam inside the slit 111 to pass through;

[0042] The bias section 12 has a cutout 121 in the middle corresponding to the slit 111, which is used to suppress secondary electrons through high voltage.

[0043] The collecting section 13 is a V-shaped inverted cone 131 with its opening facing the bias section 12. It is used to collect electrons passing through the slit 111 and suppress the escape of the initial products after beam bombardment. Under the premise of ensuring full collection of beam particles, the inclined cone surface of the V-shaped inverted cone 131 can increase the bombardment area of ​​the particles, thereby reducing heat deposition and temperature rise.

[0044] The fixing bracket 14 is used to fix the slit section 11, the bias section 12 and the collecting section 13 in sequence according to the direction of the stream propagation. The slit section 11, the bias section 12 and the collecting section 13 are connected by a perforation method and are pressed and fixed by ceramic screws and washers.

[0045] like Figure 2As shown, the slit section 11 includes two metal plates. A slit 111 is machined at the center of the first metal plate 112, perpendicular to the direction of motor movement, using wire cutting. The width of this slit 111 affects the spatial resolution of the cross-sectional measurement; theoretically, the smaller the slit width, the better, i.e., the smaller the slit width, the higher the spatial resolution of the cross-sectional measurement. However, in practical applications, due to limitations of the wire cutting process, only relatively small values ​​can be selected. In this embodiment, the slit width of the slit 111 is preferably 0.2 mm, so the limit resolution of the measurement in this embodiment is also around 0.2 mm. In this embodiment, the length of the slit 111 is preferably 50 mm, not less than the beam envelope size. A recessed cooling water channel 114 is provided within the first metal plate 113. The first metal plate 113 consists of two copper half-layers. The recessed cooling water channel 114 is extracted from each copper half-layer, and then the two copper half-layers are snapped together and welded. High-temperature explosive welding is used to weld the first metal plate and the second metal plate into a single unit. Because tantalum has a high melting point of 2980℃ and copper has a high thermal conductivity, in this embodiment, the first metal plate 112 is a tantalum layer and the first metal plate 113 is a copper layer. However, these two materials are not the only options; other metal materials with similar properties can also be used in this embodiment. The material thickness is determined based on the beam energy and range. In this embodiment, it is intended to be applied to the MeV energy region of the MEBT segment of the accelerator. Therefore, the thickness of the tantalum layer is selected as 1.5mm. The thickness of the tantalum layer is not less than the particle range. The slit width of the tantalum layer is 0.2mm, and the slit length is 50mm. The thickness of the copper layer is approximately 17.5mm, which is determined by factors such as the thickness of a single copper layer, the diameter of the water pipe, and the processing technology. The inner tangent section of the slit 111 of the tantalum layer is a right angle to ensure that beam particles outside the slit are completely blocked from passing through. The inner tangent section of the slit 111 of the copper layer is an oblique angle, so the inner tangent section will expand in the direction of beam propagation, so that the beam passing through here will not be completely blocked by the copper layer due to beam divergence caused by its lateral emission. The oblique angle needs to be greater than the emission divergence angle; in this embodiment, the oblique angle is 10°.

[0046] like Figure 3 As shown, in this embodiment, the biasing part 12 is made of pure copper, but it is not limited to this; other conductive metal materials are also acceptable. Relatively speaking, pure copper has a higher conductivity and better processing flexibility. In this embodiment, the preferred size of the cut 121 is 51 × 9.5 mm. 2 The cut 121 has an angled cross-section, the angle of which is not less than the angle of the inner tangent cross-section of the copper layer slit 111, meaning its opening size is not less than the width of the slit 111 and the reverse extension width of the copper layer angle of the slit 111, and not greater than the opening of the V-shaped inverted cone 131, in order to form a better distribution of electric field equipotential lines and a secondary electron suppression effect. In this embodiment, the angle of the cut 121 cross-section is preferably 11.3°.

[0047] like Figure 4 As shown, in this embodiment, the collecting part 13 is made of pure copper, but it is not limited to this; other conductive metal materials are also acceptable. Relatively speaking, pure copper has a higher conductivity and better processing plasticity. Several triangular serrations 132 are provided on the inner surface of the V-shaped inverted cone 131. The half-angle of the cone peak of the V-shaped inverted cone 131 is 52.5°, and the half-angle of the cone base angle is 18.75°, which is not less than the inclination angle of the cross-section of the cut 121 of the biasing part 12. This structural design facilitates increasing the probability of secondary electrons returning inside the cone, collecting all the beam particles passing through the slit 111, and has high heat-resistant deposition performance as well as the ability to prevent secondary electrons from escaping. The opening of the V-shaped inverted cone 131 has a width perpendicular to the slit 111 that is not less than the width of the cut 121 of the biasing part 12; the opening of the V-shaped inverted cone 131 has a width parallel to the slit 111 that is not less than the length of the cut 121 of the biasing part 12; and the cone base angle is not less than the inclination angle of the cross-section of the cut 121 of the biasing part 12. The dimensions of the opening of the V-shaped inverted cone 131 are 52 × 20 mm. 2 .

[0048] Example 2

[0049] Based on the same inventive concept, this embodiment discloses a scanning profile measurement device suitable for low-energy high-current beams, such as... Figure 5 As shown, it includes: a measuring target head 1, a motion module 2, and a data processing module 3;

[0050] The measuring target 1 adopts the scanning profile measuring target 1 suitable for low-energy high-current beams in Embodiment 1;

[0051] Motion module 2 is used to drive the measuring target head 1 to perform line-by-line scanning in order to obtain the current intensity information of the beam slice at different positions;

[0052] The data processing module 3 is used to analyze and process the data collected by the measuring target 1.

[0053] The measurement target 1, motion module 2 and data processing module 3 perform line-by-line scanning beam confinement and collect particle signals in the lateral direction, and finally reconstruct the beam profile distribution.

[0054] The working principle and mechanism in this embodiment are as follows: the high melting point slit 11 is used to confine the beam. Only low-energy particles that pass through the slit 111 can move to the collection part 13 and be blocked and captured. Then, the electric field generated by the bias part 12 will suppress the escape of secondary products. The current signal on the collection part 13 is then acquired by the data processing module 3. The beam is then scanned laterally in a slice manner by the motion module 2. Finally, the current intensity of each scanning point is fitted to obtain the beam profile distribution.

[0055] like Figure 6As shown, the motion module 2 includes a housing 21, a servo motor 22, a coupling 23, a lead screw 24, a transmission rod 25, a first sealing flange 26, a second sealing flange 27, a limit switch 28, a photoelectric switch 29, and a steel ruler 210. The housing 21 is used to fix the servo motor 22. The servo motor 22 is connected to the coupling 23, the lead screw 24, and the transmission rod 25 in sequence, and drives the transmission rod 25 to reciprocate. The end of the transmission rod 25 is connected to the first sealing flange 26, which is fixedly connected to the measuring target head 1. The second sealing flange 27 is located at the connection between the lead screw 24 and the transmission rod 25, and is used to fix the lead screw 24 and the transmission rod 25 to the housing 21. The limit switch 28 and the photoelectric switch 29 are used to control the position of the measuring target head 1 by limiting the position of the transmission rod 25. The steel ruler 210 is combined with the absolute position encoder on the servo motor 22 to accurately calculate the displacement of the transmission rod 25. In this embodiment, the transmission rod 25 is fixed in the second sealing flange 27 by two supporting menisci 211. Several lifting rings 212 are arranged circumferentially on the second sealing flange 27.

[0056] The motion module 2 also includes a cooling water pipe 213, a water pipe connector 214, a corrugated pipe 215, and a connecting pipe 216. The cooling water pipe 213 includes two pipes, which are connected to one end of the corrugated pipe 215 through the water pipe connector 214. The transmission rod 25 is a hollow structure with two connecting pipes 216 inside. One end of the two connecting pipes 216 is connected to the other end of the corrugated pipe 215, and the other end of the two connecting pipes 216 is connected to the input end and the output end of the cooling water circuit 114 in the first layer metal plate 113 through the through holes on the first sealing flange 26, forming a cooling circuit.

[0057] like Figure 7 As shown, the data processing module 3 includes an IV impedance amplifier, an analog-to-digital acquisition card (ADC), a programmable logic processor (FPGA), and an embedded ARM and EPICS. The data collected by the measuring target 1 is amplified by the IV impedance amplifier, and the amplified data enters the analog-to-digital acquisition card (ADC) to be converted into digital signals. The programmable logic processor (FPGA) processes the digital signals, and the embedded ARM and EPICS are used to store the digital signals and their processing results.

[0058] In another embodiment of the invention, such as Figure 8 As shown, there are two measuring targets 1. The slits 111 of both measuring targets 1 are at a 45-degree angle to the movement direction of the motion module 2. When the motion module 2 drives the measuring targets to move linearly, a single scan can perform profile measurements in both horizontal and vertical directions. This embodiment enables a single detector to measure the bidirectional beam profile dimensions in a single scan.

[0059] Example 3

[0060] Based on the same inventive concept, to demonstrate the actual measurement effect of the scanning profile measurement device applicable to low-energy high-current beams in this invention, this embodiment first evaluates the field distribution of the bias section 12 using a three-dimensional electromagnetic simulation program. The actual beam parameters used are as follows: protons... 1 P 1+ The energy is 2.1 MeV, the current intensity is 10 mA, and the beam has a Gaussian distribution with σx = 2.5 mm and σy = 2.5 mm.

[0061] like Figure 8 As shown, when the voltage applied by the bias section 12 is -500V, the equipotential lines between the bias section 12 and the collecting section 13 are relatively straight, and the equipotential lines are basically perpendicular to the beam entry direction, that is, the electric field distribution is parallel to the beam entry direction. It can be seen that the design of the bias section 12 in this invention can effectively reduce the escape probability of low-energy electrons below 500eV generated after beam particles bombard the collecting section 13.

[0062] Theoretically, the surface low-energy electron yield (SEY) caused by beam bombardment of the metal constitutes the main body of secondary electrons within the collection section 13. The Sternglass formula is commonly used internationally to evaluate SEY, as shown in the following equation, where the yield is proportional to the energy loss from Coulomb collisions:

[0063] SEY = (dE / dz) * P * d S / ΔE

[0064] In the formula, dE / dz represents the energy loss per unit length. The SRIM program calculates that the average energy loss of a 2.1 MeV proton in copper is approximately 69.17 MeV / mm; P indicates the escape probability of low-energy electrons, which is approximately 0.5; ds represents the escape path of surface electrons, which is approximately 1 nm; and ΔE represents the energy consumed by surface electrons escaping, which is approximately 25 eV. Substituting the parameters, we obtain SEY = 1.383, representing the number of low-energy electrons emitted from the surface of copper after a single proton bombards it with the parameters. According to the formula, assuming all low-energy electrons escape from the collector 13 in a vacuum environment, the limit of the current measurement accuracy that the bias section 12 can improve is approximately (1.38+1) / 1 = 238%. However, the bias section 12 has difficulty suppressing the high-energy electrons generated within the collector 13 due to beam bombardment. Based on the interaction distance of Coulomb collisions and the probabilities of soft and hard collisions between electrons, the total energy loss from both collision types is comparable; therefore, the yield of high-energy electrons will be much smaller than that of low-energy electrons.

[0065] The sawtooth 132 design within the collecting section 13 is such that, when high-energy electrons are emitted isotropically from the bottom of the cone, it is estimated that it can block approximately 33% more electrons, considering only the change in the cone bottom angle caused by the presence of the sawtooth 132. Furthermore, the sawtooth 132 in the middle and upper part of the cone can also cause high-energy electrons to refract back and forth, ultimately losing energy and stopping at the cone wall, which is advantageous.

[0066] like Figure 9 As shown in (a), temperature simulation of the circulating cooling loop connected in the slit section 11 was performed using ANSYS Fluent. The proton beam energy was 2.1 MeV, the current intensity was 10 mA, the 1x sigma dimension was 2.5 mm, and the water cooling conditions were set to a flow rate of 8 L / min and a water pressure of 0.4 MPa. At a pulse width of 3 ms and a repetition frequency of 3 Hz, the maximum temperature rise of the slit section 11 was approximately 875°C, and it could be effectively cooled within approximately 0.1 ms. Under the beam parameters and pulse conditions, the number of proton beam particles reaching the cone of the collection section 13 after passing through the water-cooled slit section 11 can be evaluated using a two-dimensional Gaussian integral formula.

[0067]

[0068] In the formula, n and N0 represent the particle beam and the number of particles passing through slit 111, respectively; μx and μy represent the beam center in the horizontal and vertical directions, respectively; σx = σy = 2.5 mm represent the standard deviation of the distribution in the two directions, respectively; m represents the range of several times the standard deviation in one direction. Usually, m = 3 or above can contain most of the beam particles; d = 0.2 mm represents the width of slit 111. Substituting the parameters into the integral formula, it can be estimated that when slit 111 scans to the beam center position, only about 3.2% of the particles can enter the collection section 13. It can be seen that the current intensity in the cone of collection section 13 is usually about two orders of magnitude less than that in front of slit 111.

[0069] Under a peak beam pulse power of 21kW in the accelerator's MEBT region, only a few hundred watts reach the collector section 13. Furthermore, due to the specially designed conical structure with a half-angle of 18.75°, its power-bearing area approximately increases from S to S / sin(18.75°), meaning the heat power per unit area decreases by about 3.1 times. Considering all these factors, three-dimensional thermal simulation using ANSYS shows that, under the same 3ms and 3Hz pulse beam measurement modes, the temperature rise of the collector section 13 is essentially negligible.

[0070] As a comparative example, such as Figure 9 As shown in (b), under the same beam conditions, the range of a low-energy 2.1 MeV proton in a tungsten filament using a conventional single-wire probing probe is approximately 15.38 micrometers, and its energy is approximately fully deposited on the filament surface. Considering thermal radiation, thermal conduction, and the thermal conductivity coefficient due to temperature changes, solving the differential equations reveals that at the same 3 Hz repetition frequency, with a beam pulse width of only 0.1 ms, the temperature rise can reach approximately 1300 °C.

[0071]

[0072] In the formula, ρ is the fiber density; V is the fiber volume; C pdT / dt represents the thermal capacity coefficient of the filament, and is considered as a temperature variation coefficient; dT / dt is the first derivative of temperature with time; ΔE is the energy deposited by the beam in the filament; I is the beam current intensity; A i dT represents the area of ​​the beam colliding with the filament; ε is the surface emissivity of the filament; σ is the Stefan-Boltzmann constant; T and T0 represent the filament temperature and ambient temperature, respectively; λ is the thermal conductivity of the filament, and is considered as a temperature-dependent coefficient; 2 / dl 2 This represents the second derivative of the wire temperature along the wire length, i.e., the direction of heat conduction.

[0073] At a proton beam energy of 2.1 MeV, a current intensity of 8.6 mA, a pulse width of 200 μs, and a repetition frequency of 1 Hz, the transverse horizontal profile measurement results in this embodiment are as follows: Figure 10 As shown, the beam envelope center in the lateral direction is approximately -1.43 mm, with a total width of approximately 20 mm and a scanning measurement position resolution of approximately 0.2 mm. The lateral optical parameters of the MEBT segment can be frequently and stably measured and adjusted under such high power conditions to better match the downstream superconducting segment and reduce beam loss.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific embodiments of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention. The content is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A scanning profile measurement target head suitable for low-energy high-current beams, characterized in that, include: Slit section, bias section, collection section, and fixing bracket; The slit section includes a composite plate with a slit in the middle, which is used to block the beam and allow only the beam within the slit to pass through; The bias section has a cut in the middle corresponding to the slit, which is used to suppress secondary electrons through high voltage. The collecting part is a V-shaped inverted cone with its opening facing the biasing part, used to collect electrons passing through the slit; The fixed bracket is used to fix the slit, bias, and collection parts sequentially according to the beam propagation direction; several triangular serrations are provided on the inner surface of the V-shaped inverted cone to increase the probability of secondary electrons returning inside the cone.

2. The scanning profile measurement target head suitable for low-energy high-current beams as described in claim 1, characterized in that, The slit section includes two metal plates. A slit is machined in the center of the first metal plate using wire cutting technology. A recessed cooling water channel is provided in the second metal plate. The first and second metal plates are welded into a whole using high-temperature explosive welding.

3. The scanning profile measurement target head suitable for low-energy high-current beams as described in claim 2, characterized in that, The first metal plate is a tantalum layer, the second metal plate is a copper layer, the inner tangent section of the slit in the tantalum layer is a right angle, and the inner tangent section of the slit in the copper layer is an oblique angle; the cut section of the biasing part is an oblique angle, and the oblique angle of the cut section is not less than the oblique angle of the inner tangent section of the slit in the copper layer.

4. The scanning profile measurement target head suitable for low-energy high-current beams as described in claim 3, characterized in that, The width of the opening of the V-shaped inverted cone perpendicular to the slit direction is not less than the width of the cut of the biasing part; the width of the opening of the V-shaped inverted cone parallel to the slit direction is not less than the length of the cut of the biasing part; the cone base angle is not less than the inclination angle of the cut section of the biasing part.

5. A scanning profile measurement device suitable for low-energy high-current beams, characterized in that, include: Measurement target head, motion module, and data processing module; The measuring target is a scanning profile measuring target suitable for low-energy high-current beams as described in any one of claims 1-4; The motion module is used to drive the measuring target head to perform line-by-line scanning; The data processing module is used to analyze and process the data collected by the measuring target.

6. The scanning profile measurement device suitable for low-energy high-current beams as described in claim 5, characterized in that, The motion module includes a housing, a servo motor, a coupling, a lead screw, a transmission rod, a first sealing flange, a second sealing flange, a limit switch, a photoelectric switch, and a steel ruler. The housing is used to fix the servo motor, which is sequentially connected to the coupling, lead screw, and transmission rod, and drives the transmission rod to reciprocate. The end of the transmission rod is connected to the first sealing flange, which is fixedly connected to the measuring target head. The second sealing flange is disposed at the connection between the lead screw and the transmission rod, and is used to fix the lead screw and the transmission rod to the housing. The limit switch and photoelectric switch are used to control the position of the measuring target head by limiting the position of the transmission rod. The steel ruler, combined with the absolute position encoder on the servo motor, is used to accurately calculate the displacement of the transmission rod.

7. The scanning profile measurement device suitable for low-energy high-current beams as described in claim 6, characterized in that, The motion module also includes a cooling water pipe, a water pipe connector, a corrugated pipe, and a connecting pipe. The cooling water pipe includes two pipes, which are respectively connected to one end of the corrugated pipe through the water pipe connector. The transmission rod is a hollow structure with two connecting pipes installed inside. One end of the two connecting pipes is connected to the other end of the corrugated pipe, and the other end of the two connecting pipes is connected to the input and output ends of the cooling water circuit in the second layer of metal plate through through holes on the first sealing flange, forming a cooling circuit.

8. The scanning profile measurement device for low-energy high-current beams as described in claim 5, characterized in that, There are two measuring targets, and the slits of the two measuring targets are at a 45-degree angle to the movement direction of the motion module. When the motion module drives the test target to move in a straight line, a single scan can perform cross-sectional measurements in both horizontal and vertical directions.

9. The scanning profile measurement device for low-energy high-current beams as described in claim 6, characterized in that, The data processing module includes an IV impedance amplifier, an analog-to-digital acquisition card (ADC), a programmable logic processor (FPGA), and embedded ARM and EPICS. The data collected by the measuring target is amplified by the IV impedance amplifier. The amplified data is then converted into a digital signal by the analog-to-digital acquisition card (ADC). The programmable logic processor (FPGA) processes the digital signal. The embedded ARM and EPICS are used to store the digital signal and the processing results.

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