CN114047540B - Measuring method and measuring system for beam current density distribution of high-current pulse electron beam - Google Patents
Measuring method and measuring system for beam current density distribution of high-current pulse electron beam Download PDFInfo
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- CN114047540B CN114047540B CN202111143404.2A CN202111143404A CN114047540B CN 114047540 B CN114047540 B CN 114047540B CN 202111143404 A CN202111143404 A CN 202111143404A CN 114047540 B CN114047540 B CN 114047540B
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Abstract
The invention provides a measuring method and a measuring system for beam current density distribution of a strong current pulse electron beam, which solve the problem that the current beam current measuring method can not realize beam current density measurement of the complete section of the strong current pulse electron beam. The method comprises the following steps: step one, manufacturing a Cerenkov radiation conversion target; step two, constructing a measuring system; step three, collecting facula images; step four, obtaining the relative intensity distribution of the Cerenkov radiation through the gray value distribution of the facula image; and fifthly, acquiring beam current density distribution. The method provides a design process of the Cerenkov radiation target, thereby providing a basis for realizing beam current density distribution measurement. Meanwhile, the method provides a beam spot image processing method, and the gray value distribution of the beam spot image is converted into beam current density distribution by the method, so that beam current density distribution measurement on the complete section of the strong current pulse electron beam is realized.
Description
Technical Field
The invention belongs to the technical field of pulse power, and particularly relates to a measuring method and a measuring system for beam current density distribution of a high-current pulse electron beam.
Background
The pulse power device utilizes a diode to generate a high-current pulse electron beam, and the electron beam bombards an anode target of the diode to generate X rays. The parameters of beam intensity, beam density, spatial distribution and the like of the strong current pulse electron beam are directly related to the intensity distribution of the X-ray radiation field. The energy of the high-current pulse electron beam can reach millions of eV, the intensity of the beam can reach hundreds of kiloA, and the beam measuring equipment is extremely easy to be damaged or invalid due to electron bombardment due to high electron energy and high electron beam intensity, and the X-ray penetrating capacity in the measuring environment is extremely high, so that high requirements are put on the shielding and electromagnetic interference resisting capacity of the measuring system.
Chinese patent CN103315711a discloses a medical cerenkov fluorescent imaging system through an endoscope, the system uses the endoscope to collect cerenkov fluorescent signals emitted by combining a detected object and a probe, and obtains cerenkov fluorescent images inside the detected object through optical fiber transmission and photoelectric conversion, thereby realizing high-precision diagnosis of medical biopsy. However, this method is directed to a subject in a narrow and curved space, and has a limited diagnostic area.
Chinese patent CN102981180a discloses a water cerenkov light high-energy particle detector, which uses water as a radiator, uses a light collecting device in the detector to collect the generated cerenkov light, and after photoelectric conversion and analog-to-digital conversion, the cerenkov light is finally stored and recorded by a data acquisition device for detecting the particle number and energy of high-energy cosmic particles. However, this method uses water as a radiator, and is not suitable for a high-current pulsed electron beam environment. .
In the paper "real-time measurement of beam spots of high-current short-pulse electron beams" by volume 15 and phase 4 of journal of high-laser and particle beams, chen Saifu et al, which discloses a real-time measurement of beam spots of high-current short-pulse electron beams, quartz glass is used as a radiator in the literature, and a single-frame luminous image of the radiator is shot through a camera for measuring the beam spots of electron beams of a linear accelerator. However, in this method, only beam spot information is acquired for a linear accelerator having low beam intensity, and no beam intensity diagnosis is performed.
In the paper of miniature Faraday cylinder array beam uniformity measurement in volume 27 and 5 of journal of strong laser and particle beams, huyang et al published miniature Faraday cylinder array beam uniformity measurement, the method uses other methods to diagnose the section parameters of electron beams, uses a Faraday cylinder to be arranged on the anode surface of a diode, and directly obtains the beam density intensity of part of the position on the anode surface, but the method is limited by the size of a detector, and the number of Faraday cylinders is limited, so that the strong current pulse beam density distribution information cannot be completely obtained.
Chinese patent CN102538670a discloses an optical measuring device and method for measuring the focal spot size of a micron-sized electron beam, so that the electron beam bombards a semiconductor panel, the semiconductor panel emits a beam by spontaneous radiation, and the optical measuring method is used to measure the light intensity information of the beam, thereby obtaining the beam spot of the electron beam. However, the semiconductor used in the method cannot bear the bombardment of the high-current pulse electron beam, and is only suitable for electron beams with the size reaching the micron level on equipment such as an electron microscope, a CRT and the like.
The above documents or patents describe measurement methods that take different technical measures to achieve the diagnosis of electron beam parameters. However, these techniques are not suitable for the high-current pulsed electron beam, or can only acquire beam spots, or can only realize the beam intensity measurement of local positions, and are difficult to apply to the beam intensity measurement of the full profile of the high-current pulsed electron beam.
The electron beam distribution image diagnosis can be realized by utilizing the visible light wave band cerenkov radiation generated by electrons in a thin transparent medium and by means of visible light high-speed imaging. The method can be used for measuring the density distribution of the high-current electron beam, and is not easily influenced by X-rays and electromagnetic interference. However, the strong current pulse electron beam has poor collimation, large incidence angle distribution, large cerenkov photon yield difference and difficulty in ensuring a better linear relation between cerenkov radiation intensity and beam current density; in addition, in the experiment, the diode cathode plasma luminescence coincides with the cerenkov radiation spectrum, and the imaging quality is seriously affected.
In summary, the current measurement system and experimental method based on cerenkov radiation are difficult to meet the requirement of measuring the beam current density distribution of the high-current pulse electron beam.
Disclosure of Invention
The invention aims to solve the problem that the current beam current measuring method can not realize the measurement of the beam current density of the complete section of the strong current pulse electron beam, and provides a measuring method and a measuring system of the beam current density distribution of the strong current pulse electron beam.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a measuring method of beam current density distribution of a high current pulse electron beam comprises the following steps:
step one, manufacturing a Cerenkov radiation conversion target;
1.1 Acquiring electron beam energy of the diode high-current pulse according to the diode pulse voltage, and acquiring electron beam incidence angle distribution according to a diode PIC simulation result;
1.2 A Monte Carlo model is established, the transmittance of electrons with different energies in graphite coating layers with different thicknesses is obtained, and meanwhile, the Cherenkov photon quantity change curve family of Cherenkov radiation photons generated by electrons in fused quartz glass under different diode voltages, different electron incidence angles and different fused quartz glass thicknesses is obtained;
1.3 Determining the thickness of the fused silica glass according to the electron beam energy and the electron beam incidence angle distribution obtained in the step 1.1) and combining the Cerenkov photon quantity change curve family obtained in the step 1.2), so that the Cerenkov photon quantity change is within 10% under the electron beam incidence angle distribution;
1.4 Determining the thickness of the graphite coating in the transmittance of the graphite coating with different thicknesses of the electrons obtained in the step 1.2), so that the electron transmittance and the plasma shielding luminous effect of the graphite coating meet the set requirements;
1.5 According to the thickness of the fused silica glass and the thickness of the graphite coating in the step 1.3) and the step 1.4), adding the graphite coating on the surface of the fused silica glass, and manufacturing the rear surface of the fused silica glass as a frosted surface to finish the Cerenkov radiation conversion target;
step two, constructing a measuring system;
a Rogowski coil and a Cerenkov radiation conversion target are placed along the incidence direction of the electron beam, the Cerenkov radiation conversion target is fixed on a rotary table, the included angle between the Cerenkov radiation conversion target and the incidence direction of the electron beam is 45 degrees, and a high-speed imaging unit is arranged on one side of the frosted surface of the Cerenkov radiation conversion target;
step three, collecting facula images;
collecting a rear surface light spot image of the Cerenkov radiation conversion target by using a high-speed imaging unit, wherein the light spot image comprises the spatial distribution, gray value and time information of light spots;
step four, obtaining the relative intensity distribution of the Cerenkov radiation through the gray value distribution of the facula image, namely obtaining the relative intensity distribution of the beam density at different positions of the beam profile;
step five, obtaining beam current density distribution;
obtaining the beam intensity at the imaging moment according to the beam intensity curve measured by the rogowski coil and the time information of the light spot image, and obtaining the beam density distribution on the beam profile by weighted average of the beam intensity;
5.1 Calculating to obtain the spatial resolution D of the Cerenkov radiation conversion target according to the structural parameters of the Cerenkov radiation conversion target;
5.2 According to the reduction multiple f of the high-speed imaging unit and the single pixel point size p of the high-speed imaging unit, calculating to obtain the number d=D/(f×p) of the pixels with the spatial resolution D corresponding to the imaging system;
5.3 Dividing the facula image into i areas with the size of d multiplied by d pixel points on average, and calculating the gray value sum N (i) in the single area;
5.4 Measuring electron beam current intensity I from rogowski coil 0 Obtaining the beam current density in each D X D area
Where J (i) is the beam density in each d×d region.
Further, in step 1.5), according to the structural parameters obtained in step 1.3) and step 1.4), a graphite coating is added on the surface of the fused silica glass in an electrophoresis manner.
In the second step, the cerenkov radiation conversion target is arranged on the rotary table and forms an included angle of 45 degrees with the incidence direction of the electron beam.
Further, in the first step, the thickness of the graphite coating is 10-50 mu m, and the thickness of the fused silica glass is 0.2-1mm.
Meanwhile, the invention also provides a measuring system of the beam current density distribution of the high-current pulse electron beam, which comprises a rogowski coil, a Cerenkov radiation conversion target, a rotary table, a high-speed imaging unit and a data processing unit; the rogowski coil and the cerenkov radiation conversion target are positioned in the vacuum cavity; the rogowski coil is used for acquiring the beam intensity of an electron beam and comprises a coil and a shielding box, wherein the shielding box is of an annular structure, and the coil is coated in the annular cavity; the Cerenkov radiation conversion target comprises a graphite coating and fused silica glass, wherein the graphite coating is arranged on the front surface of the fused silica glass and faces to an electron beam incident end, and the rear surface of the fused silica glass is a frosted surface; the rotary table is arranged below the Cerenkov radiation conversion target and is used for adjusting the included angle between the Cerenkov radiation conversion target and the incidence direction of the electron beam; the high-speed imaging unit is arranged on one side of the Cerenkov radiation conversion target and used for acquiring Cerenkov radiation distribution information and light spot images; the data processing unit is connected with the high-speed imaging unit, and processes the light spot image acquired by the high-speed imaging unit and the electron beam intensity acquired by the rogowski coil to obtain the beam intensity distribution on the beam profile.
Further, the high-speed imaging unit comprises a high-speed imaging camera, an optical filter and a reflecting mirror, wherein the high-speed imaging camera, the optical filter and the reflecting mirror are arranged in the electromagnetic shielding box, and the high-speed imaging camera images light spots on the rear surface of the conversion target through the optical filter and the reflecting mirror.
Further, the high-speed imaging camera is an ICCD camera or a framing camera.
Further, the high-speed imaging camera and the pulse power source are connected with the trigger, trigger delay of the pulse power source and the high-speed imaging camera is regulated through the trigger, and beam profile density distribution of the diode at different moments is obtained.
Furthermore, the rotary table is an electric rotary table or a manual rotary table, so that the included angle between the Cerenkov radiation conversion target and the incident direction of the electron beam is adjusted.
Compared with the prior art, the invention has the following beneficial effects:
1. the method of the invention provides a design process of the Cerenkov radiation conversion target, and the conversion target not only can shield plasma luminous interference, but also can ensure the linear relation between the Cerenkov radiation intensity and the beam intensity, thereby providing a foundation for realizing the measurement of the beam density distribution. Meanwhile, the method of the invention provides a beam spot image processing method, and the gray value distribution of the beam spot image is converted into beam current density distribution by the method, thereby realizing beam current density distribution measurement on the complete section of the strong current pulse electron beam.
2. The measuring system can completely acquire the beam current density distribution on the electron beam profile, and has simple structure and strong electromagnetic interference resistance. Meanwhile, the system adopts a Cerenkov radiation conversion target structure of graphite-plated fused quartz glass, so that the problem of cathode plasma luminous interference is solved.
3. The invention provides a method for selecting proper structural parameters of a Cerenkov radiation conversion target by utilizing numerical simulation, so that the linear relation between the Cerenkov radiation intensity and the beam intensity can be ensured.
Drawings
FIG. 1 is a schematic diagram of a system for measuring beam current density distribution of a high current pulsed electron beam in an embodiment of the present invention;
fig. 2 is a schematic diagram of the installation of a cerenkov radiation conversion target in an embodiment of the present invention.
Reference numerals: 1-pulse power source, 2-diode cathode, 3-vacuum cavity, 4-electron beam, 5-diode anode, 6-rogowski coil, 7-optical window, 8-cerenkov radiation conversion target, 9-electron absorption layer, 10-reflector, 11-filter, 12-high-speed imaging camera, 13-electromagnetic shielding box, 14-trigger, 15-rotary table, 16-observation window and 17-base.
Detailed Description
The invention will be described in detail below with reference to the drawings and the detailed description. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention.
The invention provides a measuring method and a measuring system for beam current density distribution of a strong current pulse electron beam based on Cerenkov radiation and high-speed optical imaging, which can acquire complete beam current density distribution information on a beam current section.
The measuring system of the beam current density distribution of the high-current pulse electron beam comprises a rogowski coil 6, a Cerenkov radiation conversion target 8, a rotary table 15, a high-speed imaging unit and a data processing unit; the rogowski coil 6, the cerenkov radiation conversion target 8 are located within the vacuum chamber 3, and the center of the cerenkov radiation conversion target 8 is located on the center line of the rogowski coil 6. The rogowski coil 6 is used for measuring the intensity of the electron beam 4 passing through the cerenkov radiation conversion target 8, and specifically comprises a coil and a shielding box, wherein the shielding box is of an annular structure, the coil is coated in the annular cavity, and the shielding box is used for shielding the space electron beam 4 and X-ray interference. The Cerenkov radiation conversion target 8 main body consists of a graphite coating and fused silica glass, wherein the graphite coating is arranged on the front surface of the fused silica glass and faces the incident end of the electron beam 4, and the rear surface of the fused silica glass is a frosted surface; the structural parameters of the graphite coating and the fused silica glass are determined by the results of a Monte Carlo model on the luminous depth and luminous intensity of the electron beam 4 in a transparent medium, and the structural parameters are material thickness. Specifically, the thickness of the graphite coating is 10-50 mu m, so that the diode cathode 2 plasma luminescence transmitted from the electron incidence direction can be shielded. The thickness of the fused silica glass is 0.2-1mm. The fused silica glass has high visible light transmittance and strong electron beam 4 bombardment resistance, and the thickness of the fused silica glass is reduced as much as possible to improve the spatial resolution on the premise of ensuring the detectable intensity of the Cerenkov radiation. The rear surface of the fused silica glass is provided with a frosting surface, and the cerenkov radiation generated by the electron beam 4 is converted into light spots through the frosting surface.
The rotary table 15 can use an electric or manual mode to realize the adjustment of the included angle between the Cerenkov radiation conversion target 8 and the incident direction of the electron beam 4. The high-speed imaging unit is arranged on one side of the Cerenkov radiation conversion target 8 and used for acquiring Cerenkov radiation distribution information and obtaining a facula image. The high-speed imaging unit may particularly comprise an ICCD camera or a framing camera for accurately acquiring the Cerenkov radiation distribution information of the rear surface of the fused silica glass. The data processing unit is connected with the high-speed imaging unit, and processes the light spot image acquired by the high-speed imaging unit and the beam intensity of the electron beam 4 acquired by the rogowski coil 6 to obtain the beam density distribution on the beam profile.
The invention also provides a measuring method of the beam current density distribution of the high current pulse electron beam, which comprises the following steps:
step one, manufacturing a Cerenkov radiation conversion target 8;
1.1 Obtaining the energy of the diode high-current pulse electron beam according to the diode pulse voltage, and obtaining the incidence angle distribution of the electron beam according to the PIC simulation result of the diode;
1.2 A Monte Carlo model is established, the transmittance of electrons with different energies in graphite coating layers with different thicknesses is obtained, and meanwhile, the Cherenkov photon quantity change curve family of Cherenkov radiation photons generated by electrons in fused quartz glass under different diode voltages, different electron incidence angles and different fused quartz glass thicknesses is obtained;
1.3 Determining the thickness of fused silica glass according to the electron beam energy and the electron beam incidence angle distribution provided in the step 1.1) and combining the Cerenkov photon quantity change curve family obtained in the step 1.2), and ensuring that the Cerenkov photon quantity change is within 10% under a certain electron beam incidence angle distribution;
1.4 According to the transmittance of the graphite coating with different thicknesses of electrons with different energies obtained in the step 1.2), and simultaneously, determining the thickness of the graphite coating under the condition of ensuring higher transmittance of electrons and shielding plasma luminescence effect of the graphite coating;
1.5 According to the thickness of the fused silica glass and the thickness of the graphite coating in the step 1.3) and the step 1.4), adding the graphite coating on the surface of the fused silica glass in an electrophoresis mode, and manufacturing the rear surface of the fused silica glass as a frosted surface to finish the Cerenkov radiation conversion target 8;
step two, constructing a measuring system;
a Rogowski coil 6 and a Cerenkov radiation conversion target 8 are arranged along the incidence direction of the electron beam 4, and the Cerenkov radiation conversion target 8 is fixed on a rotary table 15 and forms an included angle of 45 degrees with the incidence direction of the electron beam 4; the high-speed imaging unit is arranged on one side of the frosting surface of the Cerenkov radiation conversion target 8;
step three, collecting facula images;
collecting a rear surface light spot image of the Cerenkov radiation conversion target 8 by using a high-speed imaging unit, wherein the light spot image comprises the spatial distribution, gray value and time information of light spots;
step four, obtaining the relative intensity distribution of the Cerenkov radiation through the gray value distribution of the facula image, namely obtaining the relative intensity distribution of the beam density at different positions of the beam profile;
step five, obtaining beam current density distribution;
obtaining the beam intensity at the imaging moment according to the beam intensity curve measured by the rogowski coil 6 and the time information of the light spot image, and obtaining the beam density distribution on the beam profile by weighted average of the beam intensity;
5.1 Calculating to obtain the spatial resolution D of the Cerenkov radiation conversion target 8 according to the structural parameters of the Cerenkov radiation conversion target 8;
5.2 According to the reduction multiple f of the high-speed imaging unit and the single pixel point size p of the high-speed imaging unit, calculating to obtain the number d=D/(f×p) of the pixels with the spatial resolution D corresponding to the imaging system;
5.3 Dividing the facula image into i areas with the size of d multiplied by d pixel points on average, and calculating the gray value sum N (i) in the single area;
5.4 Measuring the beam intensity I of the electron beam 4 based on the rogowski coil 6 0 Obtaining the beam current density in each D X D area
Where J (i) is the beam density in each d×d region.
The method provides a design method of the Cerenkov radiation target, and the target can shield plasma luminous interference and ensure the linear relation between the Cerenkov radiation intensity and the beam intensity, thereby providing a basis for realizing the measurement of the beam density distribution. Meanwhile, the method of the invention provides a beam spot image processing method, and the gray value distribution of the beam spot image is converted into beam current density distribution by the method, thereby realizing beam current density distribution measurement on the complete section of the strong current pulse electron beam.
As shown in fig. 1 and 2, the beam current density distribution measuring system of the present invention uses a self-magnetic pinch diode as an example, the vacuum chamber 3 is mounted at the end of the diode, and is closely attached to the diode anode 5, and the electron absorption layer 9 is mounted at the end of the vacuum chamber 3. The rogowski coil 6 is mounted on the inner wall of the vacuum chamber 3. The electron beam 4, after being generated from a diode, passes through the diode anode 5 into the vacuum chamber 3, through the rogowski coil 6, and impinges on the cerenkov radiation conversion target 8 at an angle of incidence. When the electron velocity is greater than the speed of light in the cerenkov radiation conversion target 8, cerenkov radiation is generated. The radiation photons enter the high-speed imaging unit after being scattered by the rear surface of the Cerenkov radiation conversion target 8. The imaging system is placed in an electromagnetic shielding box 13, and a high-speed imaging camera 12 images light spots on the rear surface of the cerenkov radiation conversion target 8 through a filter 11 and a reflecting mirror 10. When the device is used, the trigger delay of the pulse power source 1 and the high-speed imaging camera 12 is regulated by the trigger 14, so that the beam profile density distribution of the diode at different moments can be obtained.
Before starting the experiment, the conversion target structure parameters were determined according to the design method of the cerenkov radiation conversion target 8. The graphite coating with the thickness of several microns on the surface of the conversion target can effectively shield the plasma luminescence interference of the diode cathode 2, simultaneously ensure the high penetration rate of the electron beam 4, has high graphite melting point, is not easy to vaporize and fall off when being bombarded by electrons, and can realize the repeated use of the Cerenkov radiation conversion target 8. And according to the diode operating parameters (pulse voltage and electron incidence angle distribution), a Monte Carlo model is established to estimate the yield of the Cerenkov radiation photons in the fused silica glass under different diode operating parameters. On the premise of ensuring that the photon yield and the beam intensity have better linear relation, the thickness of fused quartz glass is reduced as much as possible so as to improve the spatial resolution. The thickness of the fused silica glass is determined by comprehensively considering the requirements of spatial resolution, photon yield and the like.
In the experiment, as shown in fig. 2, the cerenkov radiation conversion target 8 and the precision rotary table 15 are fixed on the base 17 together, and the included angle between the conversion target and the electron beam 4 is adjusted by rotating the precision rotary table 15. The observation window 16 is used for observing the state of the conversion target before and after the experiment, and the optical window 7 is used for imaging the rear surface of the conversion target by the high-speed imaging unit. After the high-speed imaging unit acquires the light spot image, the spatial distribution, the intensity distribution and the time information of the light spot are obtained through image processing, and finally the beam current density distribution condition on the beam current section is obtained.
Claims (10)
1. The measuring method of the beam current density distribution of the high current pulse electron beam is characterized by comprising the following steps:
step one, manufacturing a Cerenkov radiation conversion target;
1.1 Acquiring electron beam energy of the diode high-current pulse according to the diode pulse voltage, and acquiring electron beam incidence angle distribution according to a diode PIC simulation result;
1.2 A Monte Carlo model is established, the transmittance of electrons with different energies in graphite coating layers with different thicknesses is obtained, and meanwhile, the Cherenkov photon quantity change curve family of Cherenkov radiation photons generated by electrons in fused quartz glass under different diode voltages, different electron incidence angles and different fused quartz glass thicknesses is obtained;
1.3 Determining the thickness of the fused silica glass according to the electron beam energy and the electron beam incidence angle distribution obtained in the step 1.1) and combining the Cerenkov photon quantity change curve family obtained in the step 1.2), so that the Cerenkov photon quantity change is within 10% under the electron beam incidence angle distribution;
1.4 Determining the thickness of the graphite coating in the transmittance of the graphite coating with different thicknesses of the electrons obtained in the step 1.2), so that the electron transmittance and the plasma shielding luminous effect of the graphite coating meet the set requirements;
1.5 According to the thickness of the fused silica glass and the thickness of the graphite coating in the step 1.3) and the step 1.4), adding the graphite coating on the surface of the fused silica glass, and manufacturing the rear surface of the fused silica glass as a frosted surface to finish the Cerenkov radiation conversion target;
step two, constructing a measuring system;
a Rogowski coil and a Cerenkov radiation conversion target are placed along the incidence direction of the electron beam, the Cerenkov radiation conversion target is fixed on a rotary table, the included angle between the Cerenkov radiation conversion target and the incidence direction of the electron beam is 45 degrees, and a high-speed imaging unit is arranged on one side of the frosted surface of the Cerenkov radiation conversion target;
step three, collecting facula images;
collecting a rear surface light spot image of the Cerenkov radiation conversion target by using a high-speed imaging unit, wherein the light spot image comprises the spatial distribution, gray value and time information of light spots;
step four, obtaining the relative intensity distribution of the Cerenkov radiation through the gray value distribution of the facula image, namely obtaining the relative intensity distribution of the beam density at different positions of the beam profile;
step five, obtaining beam current density distribution;
obtaining the beam intensity at the imaging moment according to the beam intensity curve measured by the rogowski coil and the time information of the light spot image, and obtaining the beam density distribution on the beam profile by weighted average of the beam intensity;
5.1 Calculating to obtain the spatial resolution D of the Cerenkov radiation conversion target according to the structural parameters of the Cerenkov radiation conversion target;
5.2 According to the reduction multiple f of the high-speed imaging unit and the single pixel point size p of the high-speed imaging unit, calculating to obtain the number d=D/(f×p) of the pixels with the spatial resolution D corresponding to the imaging system;
5.3 Dividing the facula image into i areas with the size of d multiplied by d pixel points on average, and calculating the gray value sum N (i) in the single area;
5.4 Measuring electron beam current intensity I from rogowski coil 0 Obtaining the beam current density in each D X D area
Where J (i) is the beam density in each d×d region.
2. The method for measuring beam current density distribution of high current pulsed electron beam according to claim 1, wherein: in step 1.5), according to the structural parameters obtained in step 1.3) and step 1.4), adding a graphite coating on the surface of the fused silica glass in an electrophoresis mode.
3. The method for measuring beam current density distribution of high current pulsed electron beam according to claim 1, wherein: in the second step, the Cerenkov radiation conversion target is arranged on a rotary table and forms an included angle of 45 degrees with the incidence direction of the electron beam.
4. The method for measuring beam current density distribution of high current pulsed electron beam according to claim 1, wherein: in the first step, the thickness of the graphite coating is 10-50 mu m, and the thickness of the fused silica glass is 0.2-1mm.
5. A measuring system of beam current density distribution of a high-current pulse electron beam is characterized in that: comprises a rogowski coil (6), a Cerenkov radiation conversion target (8), a rotary table (15), a high-speed imaging unit and a data processing unit;
the rogowski coil (6) and the cerenkov radiation conversion target (8) are positioned in the vacuum cavity (3);
the rogowski coil (6) is used for acquiring the beam intensity of the electron beam (4), and comprises a coil and a shielding box, wherein the shielding box is of an annular structure, and the coil is coated inside an annular cavity;
the Cerenkov radiation conversion target (8) comprises a graphite coating and fused silica glass, wherein the graphite coating is arranged on the front surface of the fused silica glass and faces the incident end of the electron beam (4), and the rear surface of the fused silica glass is a frosted surface;
the rotary table (15) is arranged below the Cerenkov radiation conversion target (8) and is used for realizing the adjustment of the included angle between the Cerenkov radiation conversion target (8) and the incidence direction of the electron beam (4);
the high-speed imaging unit is arranged on one side of the Cerenkov radiation conversion target (8) and is used for acquiring Cerenkov radiation distribution information to obtain a facula image;
the data processing unit is connected with the high-speed imaging unit, and processes the light spot image acquired by the high-speed imaging unit and the electron beam intensity acquired by the rogowski coil (6) to obtain the beam intensity distribution on the beam profile.
6. The system for measuring beam current density distribution of high current pulsed electron beam according to claim 5, wherein: the high-speed imaging unit comprises a high-speed imaging camera (12), an optical filter (11) and a reflecting mirror (10) which are arranged in an electromagnetic shielding box (13), wherein the high-speed imaging camera (12) images light spots on the rear surface of the cerenkov radiation conversion target (8) through the optical filter (11) and the reflecting mirror (10).
7. The system for measuring beam current density distribution of high current pulsed electron beam according to claim 6, wherein: the high-speed imaging camera (12) and the pulse power source (1) are connected with the trigger (14), trigger delay of the pulse power source (1) and the high-speed imaging camera (12) is regulated through the trigger (14), and beam profile density distribution of the diode at different moments is obtained.
8. The system for measuring beam current density distribution of high current pulsed electron beam according to claim 7, wherein: the high-speed imaging camera (12) is an ICCD camera or a framing camera.
9. The system for measuring beam current density distribution of high current pulsed electron beam according to claim 5, wherein: the thickness of the graphite coating is 10-50 mu m, and the thickness of the fused silica glass is 0.2-1mm.
10. The system for measuring beam current density distribution of high current pulsed electron beam according to claim 5, wherein: the rotary table (15) is an electric rotary table or a manual rotary table.
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| JPS63241375A (en) * | 1987-03-27 | 1988-10-06 | Kenichi Ueda | Current measurement of electron beam |
| CN106950590A (en) * | 2017-05-08 | 2017-07-14 | 中国工程物理研究院流体物理研究所 | A kind of micron dimension conversion target assembly measured for electron beam emittance |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63241375A (en) * | 1987-03-27 | 1988-10-06 | Kenichi Ueda | Current measurement of electron beam |
| CN106950590A (en) * | 2017-05-08 | 2017-07-14 | 中国工程物理研究院流体物理研究所 | A kind of micron dimension conversion target assembly measured for electron beam emittance |
Non-Patent Citations (1)
| Title |
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| Yana Zlateva等.Cherenkov emission-based external radiotherapy dosimetry: I. Formalism and feasibility.《Medical Physics》.2019,全文. * |
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