A method and system for measuring the secondary electron emission coefficient of a dielectric material

Abstract

The application provides a method and system for measuring a secondary electron emission coefficient of a medium material, the method comprising the following steps: obtaining a total primary electron beam current, and cutting the total primary electron beam current to obtain a primary electron beam current; obtaining a beam cutting current and a sampling current, and calculating a ratio of the primary electron beam current to the beam cutting current; obtaining the beam cutting current and the sampling current of the medium material to be measured, and obtaining the secondary electron emission coefficient of the medium material to be measured under primary electron incidence energy; neutralizing accumulated charges on the surface of the medium material to be measured by using a first neutralizing electron gun and a second neutralizing electron gun; measuring the secondary electron emission coefficient under different primary electron incidence energies to obtain a secondary electron emission coefficient curve. The accumulated charges on the surface of the medium material to be measured are neutralized and removed by using the neutralizing electron gun, the problems that a long time is consumed in the previous medium material measurement process and the measurement of the secondary electron emission coefficient less than 1 cannot be realized are solved, and the complete curve of the secondary electron emission coefficient of the medium material is rapidly and accurately measured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of secondary electron emission coefficient measurement of dielectric materials, and relates to a method and system for measuring the secondary electron emission coefficient of dielectric materials. BACKGROUND

[0002] Secondary electron emission, also known as secondary emission, refers to the phenomenon of electron escape from the surface of a material when particles with a certain initial energy bombard the material. The secondary electron emission coefficient is one of the important physical parameters for measuring the secondary electron emission phenomenon, and is defined as the ratio of the number of secondary electrons emitted by the material to the number of electrons bombarding the material surface. In practical applications, the number of electrons cannot be accurately counted, and the secondary electron emission coefficient is generally measured by indirectly calculating the ratio of the electron current emitted by the material surface to the electron current bombarding the material surface. The requirements for the secondary electron emission coefficient are different in different application scenarios. Secondary electron emission can cause micro-discharge effects in space high-power microwave components, electron cloud effects in particle accelerators, and charging and dielectric breakdown phenomena induced by secondary electron emission on the surface of dielectric materials in space vehicles, etc. In these scenarios, it is desirable to have a smaller secondary electron emission coefficient. In the application fields of photomultiplier tubes, microchannel plates, etc. that utilize electron multiplication, it is desirable to have a larger secondary electron emission coefficient.

[0003] The conductive ability of dielectric materials is poor, and if the secondary electron emission coefficient is not 1, the material surface will accumulate electric charges, thereby causing measurement errors of the secondary electron emission coefficient. Therefore, before each measurement, the accumulated electric charges on the material surface must be removed. The currently commonly used surface charge removal techniques mainly include: ① natural discharge. The discharge time of the electric charges of dielectric materials is long, and it cannot be ensured that the electric charges are completely removed; ② heating. The conductivity of dielectric materials generally increases with the increase of temperature, but only the secondary electron emission coefficient at high temperature can be obtained; and ③ low-energy electron scanning. The low-energy electrons are used to bombard and neutralize the positive charges accumulated on the surface of the material, and only the measurement of the part of the curve where the secondary electron emission coefficient of the material is greater than 1 can be realized, and the positive charges may be left on the surface of the dielectric material or negative charges may be accumulated on the surface of the dielectric material due to the uncontrollable neutralization process. It can be seen that the surface charge removal technology of dielectric materials is a key technical obstacle for accurately measuring the secondary electron emission coefficient. SUMMARY

[0004] The present application aims to solve the problem in the prior art that the accumulated electric charges on the surface of dielectric materials cannot be completely removed or the complete secondary electron emission coefficient curve cannot be obtained when measuring the secondary electron emission coefficient of dielectric materials, resulting in errors in the measurement of the secondary electron emission coefficient, and to provide a method and system for measuring the secondary electron emission coefficient of dielectric materials.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A method for measuring a secondary electron emission coefficient of a medium material, comprising the following steps:

[0007] S1, obtaining a total primary electron beam current, and obtaining a primary electron beam current by cutting the total primary electron beam current;

[0008] S2, obtaining a beam cutting current and a sampling current, and calculating a ratio of the primary electron beam current to the beam cutting current;

[0009] S3, obtaining a beam cutting current and a sampling current of the medium material to be measured, and obtaining a secondary electron emission coefficient of the medium material to be measured under a primary electron incident energy;

[0010] S4, neutralizing accumulated charges on a surface of the medium material to be measured by a first neutralizing electron gun and a second neutralizing electron gun;

[0011] S5, determining whether the measurement is completed, and repeating steps S3-S4 if the measurement is not completed, to measure secondary electron emission coefficients under different primary electron incident energies, and obtaining a secondary electron emission coefficient curve of the medium material to be measured.

[0012] Further improvements of the present application are as follows:

[0013] The ratio of the primary electron beam current to the beam cutting current specifically comprises the following steps:

[0014] The Faraday cup is placed on the sample table, the primary electron gun is turned on at t0, and the primary electron gun is turned off at t1;

[0015] The total primary electron beam current I emitted by the primary electron gun T1 After cutting by the beam cutting electrode, a uniform primary electron beam current I is obtained P1 The primary electron beam current I P1 is incident on the Faraday cup;

[0016] At t1 to t2, the beam cutting current I and the sampling current I are measured and calculated by using the integral amplifier and the data acquisition circuit BC1 ; S1 Wherein I S1 = I P1 ;

[0017] According to the primary electron beam current I P1 and the beam cutting current I BC1 , the ratio K is calculated;

[0018] The incident electron energy of the primary electron gun is adjusted, and the ratio K under different incident electron energies is obtained.

[0019] The secondary electron emission coefficient of the medium material to be measured under the primary electron incident energy is specifically:

[0020] The medium material to be measured is placed on the sample table, the primary electron gun is turned on at t0, and turned off at t1 to obtain the primary electron incident energy;

[0021] The beam cutting current I BC2 and the sampling current I S2 , the actual primary electron beam current I BC2 is calculated according to the ratio K and the beam cutting current I P2 ;

[0022] The secondary electron beam current I P2 is calculated according to the primary electron beam current I S2 and the sampling current I SE ;

[0023] The secondary electron emission coefficient is calculated, which is specifically represented as:

[0024]

[0025] Wherein, σ represents the secondary electron emission coefficient, K represents the ratio of the primary electron beam current I P1 and the beam cutting current I BC1 .

[0026] The accumulated charge on the surface of the medium material to be measured is neutralized by the first neutralizing electron gun and the second neutralizing electron gun, specifically by the following steps:

[0027] When the surface of the medium material to be measured accumulates positive charge, the electron beam emitted by the first neutralizing electron gun obtains an energy of eΔV and reaches the surface of the medium material to be measured, generating negative charge and neutralizing the positive charge on the surface of the medium material to be measured;

[0028] After the positive charge is neutralized, the surface potential of the medium material to be measured decreases to 0, and the electron beam emitted by the first neutralizing electron gun cannot reach the surface of the medium material to be measured;

[0029] A negative bias voltage V N is applied to the second neutralizing electron gun, and the electron beam emitted by the second neutralizing electron gun obtains an energy of e(V N +ΔV) and reaches the surface of the medium material to be measured, generating positive charge and neutralizing the negative charge on the surface of the medium material to be measured until no charge accumulates on the surface of the medium material to be measured;

[0030] The second neutralizing electron gun continues to emit an electron beam to the surface of the medium material to be measured, and accumulates positive charge on the surface of the medium material to be measured. When ΔV>0, the electron beam emitted by the first neutralizing electron gun reaches the surface of the medium material to be measured, and the surface of the medium material to be measured has no charge or has a small amount of charge accumulation, and then the negative bias voltage V NIf positive charges accumulate on the surface, the electrons of the first and second neutralization guns will bombard the surface to generate negative charges to neutralize the positive charges until no charges accumulate, and the neutralization process is terminated.

[0031] The sampling current is equal to the primary electron beam current.

[0032] A system for measuring the secondary electron emission coefficient of a medium material comprises a primary electron gun, a beam cutting electrode, a neutralization electron gun, a collector and a sample stage.

[0033] The primary electron gun, the beam cutting electrode, the collector and the sample stage are sequentially arranged, the emission outlet of the primary electron gun is directed towards the beam cutting electrode, the electron beam emitted by the primary electron gun is cut by the beam cutting electrode, and the beam cutting current is obtained and then passes through the collector to be incident on the sample surface, the two side surfaces of the collector are respectively provided with through holes, and the first and second neutralization electron guns respectively emit electron beams to the sample surface through the through holes on the collector.

[0034] The collector is a molybdenum four-prism table with open upper and lower surfaces.

[0035] A negative bias voltage is applied between the second neutralization electron gun and the sample.

[0036] The distance between the primary electron gun and the sample is 5cm.

[0037] The energy of the primary electron gun is 70-3000eV.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The present application provides a method for measuring the secondary electron emission coefficient of a medium material, a primary electron beam with good uniformity is obtained by cutting the electron beam, the synchronous measurement of the primary electron current and the secondary electron current is realized, and the influence of the primary electron beam fluctuation on the measurement accuracy is avoided, the accumulated charges on the surface of the medium material to be measured are neutralized and removed by the first and second neutralization electron guns, the problems of long measurement time and the inability to measure the secondary electron emission coefficient less than 1 in the previous measurement process of the medium material are solved, and the rapid and accurate measurement of the complete curve of the secondary electron emission coefficient of the medium material is realized. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0041] Figure 1 Flow chart of the method for measuring the secondary electron emission coefficient of a medium material according to the present application;

[0042] Figure 2 Block diagram of the system for measuring the secondary electron emission coefficient of a medium material according to the present application;

[0043] Figure 3 Typical secondary electron emission coefficient curve of a medium material according to the present application;

[0044] Figure 4 Schematic diagram of the system for neutralizing positive charges according to the present application;

[0045] Figure 5 Schematic diagram of the system for neutralizing negative charges according to the present application;

[0046] Figure 6 Time sequence diagram of the opening of the electron gun and the application of the negative bias voltage according to the present application;

[0047] Figure 7 Secondary electron emission coefficient of silicate glass measured by the method according to the present application;

[0048] Figure 8 Secondary electron emission coefficient of Si measured by the method according to the present application.

[0049] Wherein: 1 - primary electron gun, 2 - beam cutting electrode, 3 - first neutralizing electron gun, 4 - second neutralizing electron gun, 5 - collector, 6 - sample, 7 - sample stage. DETAILED DESCRIPTION

[0050] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0052] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0053] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product of the present application is used, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used for differentiation and cannot be understood as indicating or implying relative importance.

[0054] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0055] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or indirectly connected through an intermediate medium; can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0056] Reference is made to Figure 3 , a typical secondary electron emission coefficient curve diagram of the medium material, the secondary electron emission coefficient increases first and then decreases with the incident electron energy, and when the incident electron energy is E P1 and E P2 , the secondary electron emission coefficient is 1. Figure 4 and Figure 5 are respectively the system schematic diagrams of neutralizing positive charge and neutralizing negative charge. When E P1 <E P <E P2 , σ>1, the material surface will accumulate positive charge, and the material surface potential is higher than the ground sample, and the potential difference ΔV between the two is >0. As shown in Figure 4 , the cathode of the neutralizing electron gun is at the same potential as the ground sample, and the electrons emitted by the neutralizing gun 1 obtain an energy of eΔV. If eΔV<E P1 , the incident electron beam will generate negative charge on the material surface, and the positive charge accumulated on the material surface will be neutralized, and when the positive charge is completely neutralized, ΔV=0, at this time the electrons emitted by the neutralizing gun 1 cannot reach the material surface, and the neutralization process stops. When E P <E P1 or E P >E P2When σ < 1, the material surface will accumulate negative charges, and the material surface potential is lower than the ground sample, and the potential difference ΔV between the two is ΔV < 0. As shown in Figure 5 , a negative bias voltage -V is applied between the cathode of the neutralizing electron gun and the ground sample N , and the electrons emitted by the neutralizing electron gun obtain an energy of e(V N + ΔV). Make E P1 < e(V N + ΔV) < E P2 , the incident electron beam will generate positive charges on the material surface, and neutralize the negative charges accumulated on the material surface. When the negative charges are completely neutralized, ΔV = 0, and E P1 < eV N < E P2 , the electrons will continue to bombard the material surface, and the material surface will accumulate positive charges, so that the process of neutralizing the positive charges is repeated again, and complete neutralization of the charges is achieved.

[0057] The application will be described in further detail below with reference to the accompanying drawings:

[0058] Referring to Figure 1 , the system structure diagram for measuring the secondary electron emission coefficient of the medium material of the application, including a primary electron gun, a beam cutting electrode, a neutralizing electron gun, a collector and a sample table; the primary electron gun, the beam cutting electrode, the collector and the sample table are placed in sequence, the emission outlet of the primary electron gun faces the beam cutting electrode, the electron beam emitted by the primary electron gun is cut by the beam cutting electrode, and the beam cutting current is obtained and then passes through the collector to be incident to the sample surface. The collector is a molybdenum four-prism table with open upper and lower surfaces, two side surfaces of the collector are respectively provided with through holes, and the first neutralizing electron gun and the second neutralizing electron gun respectively emit electron beams to the sample surface through the through holes on the collector. In the system, the energy range of the primary electron gun is 70-3000eV. In order to ensure complete neutralization of the charges accumulated on the surface of the medium material, the two neutralizing electron guns need to be appropriately controlled in time. The time sequence of the opening and closing of the electron gun and the application of the negative bias voltage is shown in Figure 6 , and each time period is set as: t0-t1 = 7μs, t1-t2 = 0.5s, t2-t3 = 10ms, t3-t4 = 10ms, t4-t5 = 1s, t5-t 6(0) = 0.5s. t0-t 6(0) is a complete measurement process, and the entire process takes about 2.2s, and the neutralization charge time is 1.02s, which can measure the secondary electron emission coefficient under a given energy and completely neutralize the accumulated charges. If it is necessary to measure the secondary electron emission coefficient at a higher primary electron energy, the neutralization charge time needs to be increased to ensure complete neutralization.

[0059] Referring to Figure 2The method for measuring the secondary electron emission coefficient of a medium material according to the present application comprises the following steps:

[0060] S1, obtaining the total current of the primary electron beam, and obtaining the current of the primary electron beam after cutting the total current of the primary electron beam.

[0061] S2, obtaining the beam cutting current and the sampling current, and calculating the ratio of the current of the primary electron beam to the beam cutting current.

[0062] S2.1, placing the Faraday cup on the sample table, turning on the primary electron gun at t0, and turning off the primary electron gun at t1.

[0063] S2.2, the total current I of the primary electron beam emitted by the primary electron gun T1 After cutting by the beam cutting electrode, the uniform current I of the primary electron beam is obtained P1 , the current I of the primary electron beam P1 is incident on the Faraday cup.

[0064] S2.3, at t1 to t2, measuring and calculating the beam cutting current I BC1 and the sampling current I S1 by using the integration amplifier and the data acquisition circuit, wherein I S1 = I P1 .

[0065] S2.4, according to the current I of the primary electron beam P1 and the beam cutting current I BC1 , the ratio K is calculated.

[0066] S2.5, adjusting the incident electron energy of the primary electron gun, and obtaining the ratio K under different incident electron energies.

[0067] S3, obtaining the beam cutting current and the sampling current of the medium material to be measured, and obtaining the secondary electron emission coefficient of the medium material to be measured under the incident energy of the primary electron.

[0068] S3.1, placing the medium material to be measured on the sample table, turning on the primary electron gun at t0, and turning off the primary electron gun at t1, and obtaining the incident energy of the primary electron;

[0069] S3.2, measuring the beam cutting current I BC2 and the sampling current I S2 , and calculating the actual current I of the primary electron beam BC2 according to the ratio K and the beam cutting current I P2 ;

[0070] S3.3, calculating the secondary electron beam current I P2 from the current I of the primary electron beam S2 and the sampling current I SE ;

[0071] S3.4, calculating the secondary electron emission coefficient, specifically represented as:

[0072]

[0073] wherein σ represents the secondary electron emission coefficient, K represents the ratio of the primary electron beam current I P1 and the beam cutting current I BC1 .

[0074] S4, neutralizing the accumulated charge on the surface of the medium material to be measured by the first neutralizing electron gun and the second neutralizing electron gun.

[0075] S4.1, when the surface of the medium material to be measured accumulates positive charge, the electron beam emitted by the first neutralizing electron gun obtains an energy of eΔV and reaches the surface of the medium material to be measured, generating negative charge and neutralizing the positive charge on the surface of the medium material to be measured;

[0076] S4.2, after the positive charge is neutralized, the potential of the surface of the medium material to be measured decreases to 0, and the electron beam emitted by the first neutralizing electron gun cannot reach the surface of the medium material to be measured;

[0077] S4.3, a negative bias voltage V N is applied to the second neutralizing electron gun, and the electron beam emitted by the second neutralizing electron gun obtains an energy of e(V N +ΔV) and reaches the surface of the medium material to be measured, generating positive charge and neutralizing the negative charge on the surface of the medium material to be measured, until no charge accumulates on the surface of the medium material to be measured;

[0078] S4.4, the second neutralizing electron gun continues to emit an electron beam to the surface of the medium material to be measured, and positive charge accumulates on the surface of the medium material to be measured; when ΔV>0, the electron beam emitted by the first neutralizing electron gun reaches the surface of the medium material to be measured, and the surface of the medium material to be measured has no charge or has a small amount of charge accumulation, and then the negative bias voltage V N is stopped being applied to the second electron neutralizing gun; if positive charge accumulates on the surface, the electrons of the first neutralizing electron gun and the second electron neutralizing gun bombard the surface to generate negative charge to neutralize the positive charge, until no charge accumulates, and the neutralization process is terminated.

[0079] S5, determining whether the measurement is completed, and repeating steps S3-S4 if not, to measure the secondary electron emission coefficient under different primary electron incident energies, and obtain the secondary electron emission coefficient curve of the medium material to be measured.

[0080] Embodiment

[0081] The method for measuring the secondary electron emission coefficient of a medium material in the present application specifically comprises the following steps:

[0082] Step 1, the Faraday cup is placed on the sample stage, the primary electron gun is turned on at t0 and turned off at t1. The total primary electron beam current is I T1 , after the beam cutting electrode cuts, the uniform primary electron beam current I P1 is incident on the Faraday cup. From t1 to t2, the beam cutting current I BC1 and the sampling current I P1 equal to I S1 are measured and calculated by using the integrating amplifier and data acquisition circuit. Due to external interference, I T1 at the same energy will change with the test, thus producing different I P1 . However, the ratio of I P1 to I BC1 is constant at the same energy.

[0083] The value of K at the same energy. For subsequent measurements, only the beam cutting electrode current I BC2 needs to be measured, and the actual primary electron beam current I BC2 is calculated by K I P2 , thereby reducing the experimental error of the total electron beam current fluctuation. Since there is no charge accumulation on the Faraday cup, t2-t 6(0) does not work in measuring K.

[0084] Step 2, the material to be measured is placed on the sample stage, from t0 to t1, the system works in the same way as when measuring K, and the beam cutting electrode current I BC2 and the sampling current I S2 are measured. A bias voltage of +50V is applied on the collector to ensure effective collection of secondary electrons generated by the sample and reduce measurement error. Therefore, the secondary electron beam current I SE can be expressed as I P2 = I S2 + I SE , and the secondary electron emission coefficient

[0085]

[0086] Step 3, at t2, the first neutralizing electron gun and the second neutralizing electron gun start working. If the material surface accumulates positive charge, the electron beam emitted by the first neutralizing electron gun obtains an energy of eΔV and reaches the material surface. Since eΔV < E P1 , the neutralizing electron generates a negative charge that neutralizes the positive charge on the material surface. When the positive charge is neutralized, the material surface potential drops to 0, and the electrons emitted by the first neutralizing electron gun cannot reach the material surface. At t3, the negative bias voltage is applied to meet E P1 < e (V N + ΔV) < E P2The second neutralizing electron gun is applied with a negative bias voltage in the range of - 10 to - 1000 V, and the first neutralizing electron gun is applied with a positive bias voltage in the range of 0 to 1000 V. The positive charges generated by the second neutralizing electron gun neutralize the negative charges on the surface of the material until no charge is accumulated on the surface of the material. However, the electrons from the second neutralizing electron gun still bombard the sample, and the material surface will accumulate positive charges. Once ΔV > 0, the electrons emitted by the first neutralizing electron gun with energy eΔV will reach the sample surface. Finally, no charge or a small amount of positive charge is accumulated on the sample surface, i.e. the surface potential is very low. Then, the negative bias voltage applied to the second neutralizing electron gun is stopped at t4. Assuming that positive charges are accumulated on the surface of the material, the electrons from the first neutralizing electron gun and the second neutralizing electron gun will bombard the surface of the material to generate negative charges to neutralize the positive charges until no charge is accumulated on the surface of the material, and the neutralization process will automatically terminate.

[0087] Step 4, at t5, all neutralizing electron guns are turned off, and the next measurement of the secondary electron emission coefficient of the primary electron with a different energy is waited for. Until t 6(0) , a complete measurement process is finished.

[0088] Step 5, steps 2-4 are repeated to measure the secondary electron emission coefficient under different primary electron incident energies until all measurements are completed.

[0089] Referring to Figure 7 and Figure 8 , respectively, are the secondary electron emission coefficients of silicate glass and Si measured by the method of the present application.

[0090] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of measuring the secondary electron emission coefficient of a dielectric material, characterized in that, The method comprises the following steps: 1-3 S1, obtaining a total primary electron beam current, and obtaining a primary electron beam current after cutting the total primary electron beam current; S2, obtaining a beam cutting current and a sampling current, and calculating a ratio of the primary electron beam current to the beam cutting current, and specifically comprising the following steps: The Faraday cup is placed on the sample stage, and the electron gun is turned on at t 0 and turned off at t 1. total beam current of the primary electron beam emitted by the primary electron gun I T1 obtaining a uniform primary electron beam current after cutting by the beam cutting electrode I P1 primary electron beam current I P1 incident on the Faraday cup; At t 1 to t 2, the beam cutting current is measured and calculated by using an integrating amplifier and a data acquisition circuit I BC1 and the sampling current I S1 where I S1 = I P1 ; According to the electron beam current I P1 and the beam cutting current I BC1 , the ratio of which is calculated K ; Adjusting the incident electron energy of the electron gun once to obtain the ratio under different incident electron energies K ; S3, obtaining a beam cutting current and a sampling current of a to-be-measured medium material, and obtaining a secondary electron emission coefficient of the to-be-measured medium material under a primary electron incident energy, and specifically comprising: The medium material to be tested is placed on the sample table, and the first electron gun is turned on at 0, and the first electron incident energy is acquired when the first electron gun is turned off at 1. t 0, and the first electron incident energy is acquired when the first electron gun is turned off at 1. t 0, and the first electron incident energy is acquired when the first electron gun is turned measured beam chopping current I BC2 and the sampling current I S2 , according to the ratio K and the beam chopping current I BC2 calculating the actual primary electron beam current I P2 ; by the primary electron beam current I P2 and the sampling current I S2 the secondary electron beam current I SE ; calculating the secondary electron emission coefficient, and specifically represented as: wherein, represents the secondary electron emission coefficient, K represents the primary electron beam current I P1 and the beam cutting current I BC1 the ratio of the beam cutting current to the primary electron beam current. S4, neutralizing accumulated charges on a surface of the to-be-measured medium material by the first neutralizing electron gun and the second neutralizing electron gun; S5, judging whether the measurement is completed, and repeating steps S3-S4 if the measurement is not completed, and measuring the secondary electron emission coefficient under different primary electron incident energies to obtain a secondary electron emission coefficient curve of the to-be-measured medium material.

2. A method of measuring the secondary electron emission coefficient of a dielectric material as claimed in claim 1, characterized in that, The neutralizing accumulated charges on the surface of the to-be-measured medium material by the first neutralizing electron gun and the second neutralizing electron gun specifically comprises the following steps: When the surface of the medium material to be tested accumulates positive charges, the electron beam emitted by the first neutralizing electron gun obtains an energy of eΔ V and reaches the surface of the medium material to be tested, generating negative charges and neutralizing the positive charges on the surface of the medium material to be tested; After the positive charges are neutralized, the surface potential of the to-be-measured medium material is reduced to 0, and the electron beam emitted by the first neutralizing electron gun cannot reach the surface of the to-be-measured medium material. Applying a negative bias voltage V N To the second neutralizing electron gun, the electron beam emitted by the second neutralizing electron gun obtains the energy of e V N +Δ V ) and reaches the surface of the medium material to be measured, generates positive charges, neutralizes the negative charges on the surface of the medium material to be measured, and until no charges accumulate on the surface of the medium material to be measured; The second neutralizing electron gun continues to emit electron beams to the surface of the medium material to be tested, and positive charges are accumulated on the surface of the medium material to be tested. When Δ V > 0, the electron beams emitted by the first neutralizing electron gun reach the surface of the medium material to be tested, and the surface of the medium material to be tested has no electric charge or a small amount of charge accumulated, and then the negative bias voltage applied to the second electron neutralizing gun is stopped V N If positive charges are accumulated on the surface, the electrons of the first neutralizing electron gun and the second neutralizing electron gun will bombard the surface to generate negative charges to neutralize the positive charges until no charge is accumulated, and the neutralization process is terminated.

3. A method of measuring the secondary electron emission coefficient of a dielectric material as claimed in claim 1, characterized in that, The sampling current I S1 And the sampling current I S2 Is equal to the primary electron beam current.

4. A system for measuring the secondary electron emission coefficient of a dielectric material, based on the method for measuring the secondary electron emission coefficient of a dielectric material according to claim 1, characterized in that, The apparatus comprises a primary electron gun, a beam cutting electrode, a neutralizing electron gun, a collector and a sample table. The primary electron gun, the beam cutting electrode, the collector and the sample table are placed in sequence, and an emission outlet of the primary electron gun faces the beam cutting electrode, the electron beam emitted by the primary electron gun is cut by the beam cutting electrode, and the beam cutting current passes through the collector and is incident on the sample surface, two side surfaces of the collector are respectively provided with through holes, and the first neutralizing electron gun and the second neutralizing electron gun respectively emit electron beams to the sample surface through the through holes on the collector.

5. A system for measuring the secondary electron emission coefficient of a dielectric material as claimed in claim 4, characterized in that, The collector is a molybdenum four-prism table with open upper and lower surfaces.

6. A system for measuring the secondary electron emission coefficient of a dielectric material as claimed in claim 4, characterized in that, A negative bias voltage is applied between the second neutralizing electron gun and the sample.

7. A system for measuring the secondary electron emission coefficient of a dielectric material as claimed in claim 4, characterized in that, The distance between the primary electron gun and the sample is 5 cm.

8. A system for measuring the secondary electron emission coefficient of a dielectric material as claimed in claim 4, characterized in that, The energy of the primary electron gun is 70-3000 eV.

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