A method for judging the microdischarge risk of microwave components under different surface treatments

Abstract

A method for judging the microdischarge risk of microwave components under different surface treatments, comprising: testing the secondary electron yield data of different surface treatments of microwave components; fitting a secondary electron yield curve at the incident electron energy according to the tested secondary electron yield data; calculating the probability of the number of outgoing electrons at different incident electron energies according to the relationship between the incident electron energy and the secondary electron yield; calculating the normalized cumulative outgoing probability of electrons at different incident electron energies according to the probability of the number of outgoing electrons; calculating the critical microdischarge threshold points corresponding to different secondary electron yield curves; and judging the risk of microdischarge occurring under different surface treatments. The method of the present invention does not require the calculation of the microdischarge threshold, has accurate prediction results, and has the advantages of being fast and intuitive. This method can be used to screen surface coatings for suppressing the microdischarge effect, providing a new method for quickly evaluating surface coatings for suppressing the microdischarge effect.

Description

Technical Field

[0001] The present invention relates to a method for judging the microdischarge risk of microwave components under different surface treatments, belonging to the field of electronic science and technology. Background Art

[0002] The secondary electron multiplication effect caused by secondary electron emission is an important factor restricting the performance and reliability of accelerators, microwave sources, and aerospace microwave components. In the aerospace field, the secondary electron multiplication effect is also known as the microdischarge effect. Once it occurs, it will cause resonance equipment to detune, the noise level to increase, the output power to decrease, and even trigger low-pressure discharge, damaging the surface of microwave components. Suppressing secondary electron emission to increase the microdischarge threshold has the significant advantage of not increasing the volume and weight of components, and it is the preferred technical approach to solve the microdischarge effect. To suppress secondary electron emission on the surface of microwave components, one is to coat a film layer with a low secondary electron yield on the surface, and the other is to reduce the secondary electron yield through surface treatment.

[0003] When conducting research on coatings for suppressing the microdischarge effect, a large number of experimental values of secondary electron yield (SEY) at discrete energy points are usually obtained through secondary electron yield tests. In the past, in order to verify whether these coatings have the effect of suppressing the microdischarge effect, usually these measured secondary electron yields are fitted and then put into the microdischarge simulation software for threshold calculation. If the calculated microdischarge threshold is high, it is considered that the film layer has good microdischarge suppression ability, and even the film layer is directly coated on the microwave component, and then a microdischarge test is performed to judge whether it has microdischarge suppression ability according to the test results. When developing a microdischarge suppression film layer, a large number of experimental film layers will be produced. Whether through microdischarge simulation software or microdischarge experiments, the microdischarge simulation and microdischarge experiments on a large number of experimental film layers have the disadvantages of slow speed and large time consumption, and cannot immediately evaluate the microdischarge suppression ability of the film layer and accurately screen excellent film layer processes. Summary of the Invention

[0004] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, providing a method for judging the microdischarge risk of microwave components under different surface treatments, and solving the problem of a large amount of time consumption directly caused by microdischarge simulation calculation and microdischarge experiments when suppressing microdischarge of microwave components through surface treatment.

[0005] The technical solution of the invention is: a method for judging the microdischarge risk of microwave components under different surface treatments, the steps are as follows:

[0006] (1) Test the secondary electron yield δ(Ee_in) corresponding to the incident energy point Ee_in on the surface of the microwave component under different surface treatments, and form i groups of test data of (Ee_in, δ(Ee_in)), i = 1, 2... n; n is the total number of surface treatment types;

[0007] (2) According to the secondary electron emission yield δ(Ee_in) corresponding to different incident energy points Ee_in on the i-th group of microwave components obtained from the test in step (1), the incident electron energy E corresponding to this group of test data is fitted. in and secondary electron yield δ(E in ) relationship curve;

[0008] (3) Calculating the probability of the number of emitted electrons corresponding to the incident electron energy based on the relationship curve between the incident electron energy and the secondary electron yield obtained in step (2);

[0009] (4) Calculating the normalized cumulative probability of electron emission at different incident electron energies based on the probability of the number of emitted electrons obtained in step (3);

[0010] (5) Calculate the critical micro-discharge threshold point corresponding to the secondary electron yield curve of the i-th group;

[0011] (6) Repeat steps (2)-(5) to obtain n groups of critical micro-discharge threshold points, arrange them in descending order, and then obtain the micro-discharge risk of each microwave component.

[0012] In the step (1), for each set of test data under surface treatment, the incident energy point Ee_in tested is greater than Emax, where Emax is the energy point corresponding to the maximum secondary electron yield, and the number of test data in each set is greater than 10.

[0013] In the step (2), the fitting relationship adopts the Vaughan model or the Furman model.

[0014] The calculation in step (3) obtains the probability f(E) of the number of emitted electrons corresponding to the incident electron energy. in )=[δ(E in )-fix(δ(E in ))]×[fix(δ(E in ))+1]+[fix(δ(E in ))+1-δ(E in )]×fix(δ(E in )), where δ(E in ) is the incident electron energy E in The corresponding secondary electron yield, fix() means rounding the function down.

[0015] When the incident energy point E in The corresponding secondary electron yield δ(E in )<1, the probability of emitting electrons is f(E in )=δ(E in );

[0016] When 1 ≤ δ(E in ) < 2, the probability of the emitted electron is f(E in ) = 2 - δ(E in ) + 2(δ(E in ) - 1);

[0017] When 2 ≤ (E in )δ < 3, the probability of the emitted electron is f(E in ) = 2(3 - δ(E in )) + 3(δ(E in ) - 2).

[0018] In the step (4), the normalized electron cumulative emission probability χ(E in ) is:

[0019]

[0020] In the formula, f(E) is calculated according to the step (3);

[0021] The process of calculating the critical microdischarge threshold point corresponding to the secondary electron yield curve in the step (5) is: let the normalized electron cumulative emission probability χ(E in ) = 1, and define the E in at this time as Ea, then the incident electron energy point Ea is the critical microdischarge threshold point.

[0022] In the step (6), the smaller the critical microdischarge threshold point Ea is, the more likely the microwave component with the secondary electron yield test data at this set of incident energies as the surface is to have microdischarge.

[0023] The advantages of the present invention compared with the prior art are as follows:

[0024] (1). The present invention can quickly screen the secondary electron yield for suppressing the microdischarge effect. By calculating the normalized electron cumulative emission probability, the effect of different secondary electron yields in suppressing microdischarge is judged from the point where the normalized electron cumulative emission probability is 1, and the screening result is accurate and reliable;

[0025] (2). The method of the present invention can judge the effect of suppressing microdischarge by simply calculating the secondary electron yield, avoiding the time cost of microdischarge simulation and microdischarge test, and having the advantage of high speed.

[0026] (3). The method of the present invention is simple and intuitive, only needs to test the secondary electron yields of different surface treatments, is easy to implement, and has strong practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the technical flow chart of the present invention;

[0028] Figure 2 Secondary electron yields of three types of surface treatments tested for the present invention at different incident electron energy points, and a schematic diagram of the relationship curve between the secondary electron yield and the incident electron energy fitted according to the test results;

[0029] Figure 3 is Figure 2 A schematic diagram of the relationship between the normalized electron cumulative emission probability and the incident electron energy corresponding to the three secondary electron yield curves shown; Detailed implementation manners

[0030] The present invention will be further explained and described below in conjunction with the accompanying drawings of the specification and the detailed implementation manners.

[0031] Example 1

[0032] As Figure 1 shown, a method for judging the microdischarge risk of microwave components under different surface treatments according to the present invention is as follows:

[0033] Step 1, the secondary electron yield test data is as follows:

[0034]

[0035] Step 2, first fit the test data, and the Furman model is used for fitting. The fitting parameters of the Furman model are as follows:

[0036]

[0037]

[0038] Figure 2 The measured SEY values and the curve fitted by Furman are given.

[0039] Step 3, calculate the electron emission probability:

[0040] f(E in ) = [δ(E in ) - fix(δ(E in ))] × [fix(δ(E in )) + 1] + [fix(δ(E in )) + 1 - δ(E in )] × fix(δ(E in ));

[0041] When δ(E in ) < ˈwʌn, the probability of the emitted electron is f(E in ) = δ(E in );

[0042] When 1 ≤ δ(E in ) < 2, the electron emission probability is f(E in ) = 2 - δ(E in ) + 2(δ(E in ) - 1);

[0043] When 2 ≤ (E in )δ < 3, the probability of emitting two electrons is 3 - δ(E in ), and the probability of emitting three electrons is δ(E in ) - 2. Therefore, the electron emission probability is f(E in ) = 2(3 - δ(E in )) + 3(δ(E in ) - 2);

[0044] And so on. Given the SEY at any known E in , f(E in ) can be calculated.

[0045] Step 4: Calculate the normalized cumulative electron emission probability

[0046]

[0047] For the cumulative electron emission probability in the case of discrete points, numerical integration can be used for calculation, and the corresponding curve of the calculation result is as shown in Figure 3 .

[0048] Step 5: Find the critical incident energy point corresponding to χ = 1. According to the experimental data, the critical microdischarge threshold points E a of the three fitted curves are respectively:

[0049] Data 1: 45.3 Data 2: 54.5 Data 3: 31.4

[0050] Step 6: From the critical microdischarge threshold point E a , it can be judged that the microdischarge threshold of curve C is the lowest, and the microdischarge threshold of curve B is the highest.

[0051] Figure 2 The microdischarge thresholds of the parallel plate of 1.06 GHz·1 mm calculated from the three given SEY curves are:

[0052] Data 1: 39.3 V Data 2: 42 V Data 3: 31.5 V

[0053] The risk of the microdischarge threshold judged by this invention is consistent with the results given by the microdischarge simulation software.

[0054] As described above, the above is only the best specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The content not described in detail in the specification of the present invention belongs to the well-known technology in the art.

Claims

1. A method for judging the microdischarge risk of microwave components under different surface treatments, characterized in that Including: (1) Test the secondary electron yield δ(Ee_in) corresponding to the incident energy point Ee_in on the surface of the microwave component under different surface treatments, and form test data of i groups (Ee_in, δ(Ee_in)), where i = 1, 2…n; n is the total number of surface treatment types; (2) According to the secondary electron emission yield δ(Ee_in) corresponding to different incident energy points Ee_in on the i-th group of microwave components obtained from the test in step (1), the incident electron energy E corresponding to this group of test data is fitted. in and secondary electron yield δ(E in ) relationship curve; (3) According to the relationship curve between the incident electron energy and the secondary electron yield obtained in step (2), calculate the probability of the number of outgoing electrons corresponding to the incident electron energy; (4) According to the probability of the number of outgoing electrons obtained in step (3), calculate the normalized electron cumulative outgoing probability at different incident electron energies; (5) Calculate the critical multipactor threshold point corresponding to the secondary electron yield curve of the i-th group; (6) Repeat steps (2)-(5) to obtain n groups of critical multipactor threshold points, arrange them in descending order, and then obtain the multipactor risks of each microwave component.

2. The method for judging the microdischarge risk of microwave components under different surface treatments according to claim 1, characterized in that: In step (1), for the test data under each group of surface treatments, the tested incident energy point Ee_in > Emax, where Emax is the energy point corresponding to the maximum secondary electron yield, and the number of test data in each group > 10.

3. A method for judging the microdischarge risk of microwave components under different surface treatments according to claim 1, characterized in that: In step (2), the fitting relationship uses the Vaughan model or the Furman model.

4. A method for judging the microdischarge risk of microwave components under different surface treatments according to claim 1, characterized in that: The number probability f(E in ) of the outgoing electrons corresponding to the incident electron energy obtained in the step (3) is = [δ(E in ) - fix(δ(E in ))] × [fix(δ(E in )) + 1] + [fix(δ(E in )) + 1 - δ(E in )] × fix(δ(E in ))), where fix() represents rounding down the function.

5. A method for judging the multipactor risk of microwave components under different surface treatments according to claim 4, characterized in that When δ(E in ) < 1, the probability of the outgoing electron is f(E in ) = δ(E in ); When 1 ≤ δ(E in ) < 2, the probability of the outgoing electron is f(E in ) = 2 - δ(E in ) + 2(δ(E in ) - 1); When 2 ≤ (E in )δ < 3, the probability of the emitted electrons is f(E in ) = 2(3 - δ(E in )) + 3(δ(E in ) - 2).

6. A method for judging the microdischarge risk of microwave components under different surface treatments according to claim 4, characterized in that, The normalized electron cumulative emission probability χ(E in ) in the step (4) is as follows: where f(E) = [δ(E) - fix(δ(E))] × [fix(δ(E)) + 1] + [fix(δ(E)) + 1 - δ(E)] × fix(δ(E)).

7. A method for judging the microdischarge risk of microwave components under different surface treatments according to claim 6, characterized in that The process of calculating the critical microdischarge threshold point corresponding to the secondary electron yield curve in step (5) is as follows: Let the normalized electron cumulative emission probability χ(E in ) = 1, and define the E in at this time as Ea. Then the incident electron energy point Ea is the critical microdischarge threshold point.

8. A method for judging the microdischarge risk of microwave components under different surface treatments according to claim 7, characterized in that, In step (6), the smaller the critical multipactor threshold point Ea, the easier it is for the microwave component with the test data of the secondary electron yield at this group of incident energies as the surface to have multipactor.

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