Method for researching electric field interference degree when multiple radio frequency acceleration cavities are connected in series

Abstract

The invention provides a method for researching the electric field interference degree when multiple radio frequency acceleration cavities are connected in series, and the method comprises the following steps: taking a radio frequency acceleration cavity in the middle as an example, and obtaining the electric field interference degree when three radio frequency acceleration cavities are arranged in series and electric fields generated in adjacent radio frequency acceleration cavities at two sides leak to the radio frequency acceleration cavity in the middle; the influence on the accelerating electric field of the intermediate radio frequency accelerating cavity is U1-U3 / U3 and U2-U3 / U3; if the influence is less than 1%, considering that the mutual interference degree of the electric fields of the adjacent cavities can be ignored in the actual operation process of the ion implantation system; if the ratio is large, a cavity or a mechanical structure needs to be improved, and further research is carried out; by researching and calculating the leakage rate of adjacent electric fields when a plurality of cavities are connected in series and the influence on accelerating electric fields in the adjacent cavities, the invention solves the problems that the electric field leakage is generated in the cavities when the close series arrangement of the plurality of cavities is not considered in the current domestic cavity design, and the electric field leakage is influenced. And the interference on the electric field in the adjacent cavity is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of radio frequency acceleration cavities, and in particular relates to a method for studying the electric field interference degree when a plurality of radio frequency acceleration cavities are connected in series. Background Art

[0002] The radio frequency acceleration chamber used for ion implantation provides a high-frequency electric field for ion acceleration. There are often more than five radio frequency chambers directly arranged in series to obtain sufficient acceleration energy. In the current domestic chamber design, testing and debugging process, only the performance parameters of a single chamber are considered. When multiple chambers are closely arranged in series, the electric field generated in the chamber leaks into the adjacent chamber, which interferes with the electric field in the adjacent chamber.

[0003] In the conventional cavity electric field leakage test process, the power feeding port of a single independent cavity is often set as port 1, the sampling port is set as port 2, and then the cavity characteristic parameters are tested by connecting a network analyzer. For example, S parameters are an important parameter that can be used to represent high-frequency circuits with power. It includes the input and output ports of a single cavity. The S parameters describe the ratio of the amplitude of the output signal of a port to the amplitude of the input signal of a port at a specific frequency:

[0004]

[0005] The problem with S-parameter measurement of cavity electric field leakage is that it does not take into account the situation where signals are fed simultaneously from two or more input ports and the output signals are measured from the sampling port. We want to know whether the electric field of cavity 2 in the middle will be weakly coupled with the other two leaking electric fields when power is fed into the three cavities at the same time, and how much the electric field of cavity 2 will change. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention proposes a method for studying the electric field interference degree when multiple radio frequency acceleration cavities are connected in series. The purpose is to solve the problem that in the current domestic cavity design, testing and debugging processes, only the performance parameters of a single cavity are considered, and the electric field generated in the cavity leaks into the adjacent cavity when multiple cavities are closely arranged in series, thereby interfering with the electric field in the adjacent cavity.

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

[0008] A method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series, characterized in that it comprises the following steps:

[0009] Step 1: Assume that the number of the plurality of RF acceleration cavities connected in series is three, and the feeding ports of the three RF acceleration cavities from left to right are respectively set as port 1, port 2, and port 3, and the sampling port of the second RF acceleration cavity in the middle is set as port 4;

[0010] Step 2: Taking the middle RF accelerating cavity as an example, when the three RF accelerating cavities are arranged in series, when the electric fields generated in the adjacent RF accelerating cavities on both sides leak into the middle RF accelerating cavity, the influence on the accelerating electric field of the middle RF accelerating cavity itself is obtained: |U1-U3| / U3 and |U2-U3| / U3;

[0011] Step 3. If the influence is less than 1%, it is considered that the degree of mutual interference between the electric fields of adjacent cavities during the actual operation of the ion implantation system can be ignored; if the ratio is larger, it is necessary to improve the cavity or mechanical structure and conduct further research.

[0012] Furthermore, the specific process of step 2 is as follows:

[0013] 1) Use three power sources to feed the same power to the three cavities respectively, and the phases of the three cavities are the same. When the electric field generated by the RF accelerating cavity 1 and the RF accelerating cavity 3 leaks to the middle RF accelerating cavity 2, the signal size U1 is measured by sampling from the left gap or the right gap of the RF accelerating cavity 2;

[0014] 2) Use three power sources to feed the same power to the three cavities respectively, where RF accelerating cavities 1 and 3 are in anti-phase with RF accelerating cavity 2. When the electric field generated by RF accelerating cavity 1 and RF accelerating cavity 3 leaks to the middle RF accelerating cavity 2, the signal size measured by sampling from the left gap or the right gap of RF accelerating cavity 2 is U2;

[0015] 3) Only one power source is used to feed the same power as before into the RF acceleration cavity 2, and the signal size measured from the port 4 is U3 (E2);

[0016] 4) Calculate the size of |U1-U3| / U3 and |U2-U3| / U3.

[0017] Further, in the process 1) of step 2), when the three RF accelerating cavities are fed with the same-phase signal, the signal size is U1 measured by sampling from the left gap of the RF accelerating cavity 2, as follows: when the three cavities are fed with the same-phase signal, in addition to the electric field E2 in the left direction, there will also be the electric field E1 leaked from cavity 1 in the right direction, and there will also be the electric field E3 leaked from cavity 3 in the right direction; that is, when the RF accelerating cavity 1 and the RF accelerating cavity 3 are fed with high-frequency signals in the same phase as the cavity 2, an electric field in the opposite direction to itself will be formed in the RF accelerating cavity 2; that is, at this time, the electric field strength of the left gap of the cavity 2 is E2-E1-E3, and the signal size measured by sampling from port 4 is U1=E2-E1-E3;

[0018] Further, in the process 2) of step 2), when the three RF accelerating cavities are fed with anti-phase signals, the signal size is measured by sampling from the gap on the left side of the RF accelerating cavity 2 as U2, which is specifically as follows: when the RF accelerating cavities 1 and 3 are fed with high-frequency signals with anti-phase to the RF accelerating cavity 2, an electric field with the same direction as itself is formed in the RF accelerating cavity 2, that is, at this time, the electric field strength of the left gap of the RF accelerating cavity 2 is E2+E1+E3, where E1, E2, and E3 represent the electric fields formed by the RF accelerating cavities 1, 2, and 3, and their sizes are different, and E2 is greater than E1 and E3; the signal size measured by sampling from port 4 is U2=E2+E1+E3;

[0019] Advantages and effects of the present invention

[0020] The present invention studies and calculates the leakage of adjacent electric fields when multiple cavities are connected in series, and the influence on the acceleration electric field in the adjacent cavity itself, and optimizes the cavity-related structure through the results of the study and calculation to reduce the interference between adjacent electric fields until the interference is considered to be negligible. This solves the problem that in the current domestic cavity design, testing and debugging process, only the performance parameters of a single cavity are considered, and the problem of interference to the electric field in the adjacent cavity caused by the leakage of the electric field generated in the cavity to the adjacent cavity when multiple cavities are closely arranged in series is not considered. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of four ports of three cavities of the present invention;

[0022] Figure 2 It is a schematic diagram of the electric field of the three cavities in the same phase of the present invention;

[0023] Figure 3 This is the field distribution diagram of the leakage from cavity 1 to cavity 2 of the present invention;

[0024] Figure 4 This is the field distribution diagram of the leakage from cavity 3 into cavity 2 of the present invention;

[0025] Figure 5 The electric field distribution of the left gap of cavity 2 when the same-phase power is input to the three cavities of the present invention at the same time;

[0026] Figure 6 The electric field distribution of the left gap of cavity 2 when cavities 1 and 3 of the present invention are fed with anti-phase signals;

[0027] Figure 7 The present invention is a flow chart of a method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series. DETAILED DESCRIPTION

[0028] Design principle of the present invention

[0029] 1. The influence of the electric field of the adjacent cavity on the electric field of the current cavity: When multiple RF accelerating cavities are arranged in series, two adjacent cavities share a ground electrode. Since the beam must pass through the middle of the circular hole of the ground electrode, the ground electrode cannot be a completely closed metal baffle, and the electric field generated in the cavity will leak through the circular hole of the ground electrode to the adjacent cavity. If we can study how much this electric field leaks and how much influence it has on the accelerating electric field in the adjacent cavity, we can reduce the interference between adjacent electric fields by optimizing the cavity-related structure until we believe that this interference is negligible.

[0030] 2. Calculation of the influence of the electric field leakage of the adjacent cavity on the electric field of the current cavity:

[0031] ① Find the influence of the electric field leakage of adjacent cavities on the electric field of the current cavity under two extreme conditions, one is the case where the three cavities have the same phase, and the other is the case where the cavities on both sides of the three cavities and the middle cavity have opposite phases. The mutual influence of the electric fields of other phases between the three cavities should be between the above two extreme cases. Therefore, this embodiment only calculates the case where the three cavities have the same power and the same phase and the case where the three cavities have the same power and the opposite phase.

[0032] ② Obtain the electric field shape distribution of the three cavities themselves, such as Figure 2 As shown, since the cavity is at ground potential and the electrode in the center of the cavity is a high-voltage electrode, the direction of the electric field in each cavity is from the middle electrode of the cavity to its two sides, or from the two sides to the middle electrode;

[0033] ③ Obtain the field shape distribution of the electric field leaking from cavity 1 into cavity 2, such as Figure 3 As shown, Figure 3 The electric field shapes of cavity 2 and cavity 3 themselves are not drawn, but only the field shape distribution of cavity 1 is given. However, in fact, the electric fields of cavity 2 and cavity 3 exist. Figure 3The direction of the electric field E1 of cavity 1 received by the gap on the left side of the middle cavity 2 is the same as the direction of E1 on the right side of cavity 1, and the direction of the electric field E1 of cavity 1 received by the gap on the right side of cavity 2 is opposite to the direction of E1 on the right side of cavity 1. Because the gap on the left side of cavity 2 is directly leaked by the electric field on the right side of cavity 1, the middle electrode of cavity 2 is the negative high-voltage electrode, and the direction of the electric field of the gap on the right side of cavity 2 is from the ground electrode to the negative high-voltage electrode, that is, the direction is to the left;

[0034] ④ Obtain the field distribution of cavity 3 leaking into cavity 2. Similarly, the E3 of the right side of cavity 2 and the E3 of the left side of cavity 3 are in the same direction, and the E3 of the left side of cavity 2 and the E3 of the left side of cavity 3 are in opposite directions;

[0035] ⑤ When the three cavities input the same phase power at the same time, the electric field distribution of the left gap of cavity 2 = E2-E1-E3;

[0036] ⑥ When the anti-phase signals are fed into cavities 1 and 3, the electric field distribution of the left gap of cavity 2 = E2+E1+E3.

[0037] ⑦ Use only one power source to feed the same power as before into the RF acceleration cavity 2, and sample the signal from port 4 to obtain a signal size of E2, and set U3 = E2;

[0038] ⑧When three power sources are used to feed the same power to the three cavities respectively and in the same phase, the signal size measured by sampling from port 4 is U1=E2-E1-E3; when three power sources are used to feed the same power to the three cavities respectively, and RF acceleration cavities 1 and 3 are in anti-phase with RF acceleration cavity 2, the signal size measured by sampling from port 4 is U2=E2+E1+E3; calculate the sizes of |U1-U3| / U3 and |U2-U3| / U3, and their ratio is the influence of the electric field generated in the adjacent RF acceleration cavities on the middle RF acceleration cavity itself when the three RF acceleration cavities are arranged in series and the electric field leaks into the middle RF acceleration cavity.

[0039] Based on the above invention principle, the present invention designs a method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series, which is characterized by comprising the following steps:

[0040] Step 1: Figure 1 , Figure 7 As shown, it is assumed that the number of the multiple RF acceleration cavities connected in series is three, the feeding ports of the three RF acceleration cavities from left to right are respectively set as port 1, port 2 and port 3, and the sampling port of the second RF acceleration cavity in the middle is set as port 4;

[0041] Step 2: Figure 2 , Figure 3 , Figure 4As shown, taking the middle RF accelerating cavity as an example, when three RF accelerating cavities are arranged in series, when the electric fields generated in the adjacent RF accelerating cavities on both sides leak into the middle RF accelerating cavity, the influence on the accelerating electric field of the middle RF accelerating cavity itself is: |U1-U3| / U3 and |U2-U3| / U3;

[0042] Step 3. If the influence is less than 1%, it is considered that the degree of mutual interference between the electric fields of adjacent cavities during the actual operation of the ion implantation system can be ignored; if the ratio is larger, it is necessary to improve the cavity or mechanical structure and conduct further research.

[0043] Furthermore, the specific process of step 2 is as follows:

[0044] 1) Use three power sources to feed the same power to the three cavities respectively, and the phases of the three cavities are the same. When the electric field generated by the RF accelerating cavity 1 and the RF accelerating cavity 3 leaks to the middle RF accelerating cavity 2, the signal size U1 is measured by sampling from the left gap or the right gap of the RF accelerating cavity 2;

[0045] 2) Use three power sources to feed the same power to the three cavities respectively, where RF accelerating cavities 1 and 3 are in anti-phase with RF accelerating cavity 2. When the electric field generated by RF accelerating cavity 1 and RF accelerating cavity 3 leaks to the middle RF accelerating cavity 2, the signal size measured by sampling from the left gap or the right gap of RF accelerating cavity 2 is U2;

[0046] 3) Only one power source is used to feed the same power as before into the RF acceleration cavity 2, and the signal size measured from the port 4 is U3 (E2);

[0047] 4) Calculate the size of |U1-U3| / U3 and |U2-U3| / U3.

[0048] Furthermore, if Figure 5 As shown, in the process 1) of step 2, when the three RF accelerating cavities are fed with the same phase signal, the signal size measured by sampling from the left gap of the RF accelerating cavity 2 is U1, which is specifically as follows: when the three cavities are fed with the same phase signal, in addition to the electric field E2 in the left direction, there will also be an electric field E1 leaked from cavity 1 in the right direction, and there will also be an electric field E3 leaked from cavity 3 in the right direction; that is, when the RF accelerating cavity 1 and the RF accelerating cavity 3 are fed with high-frequency signals in the same phase as the cavity 2, an electric field in the opposite direction to itself will be formed in the RF accelerating cavity 2; that is, at this time, the electric field strength of the left gap of the cavity 2 is E2-E1-E3, and the signal size measured by sampling from port 4 is U1=E2-E1-E3;

[0049] Furthermore, if Figure 6As shown, in the process 2) of step 2), when the three RF accelerating cavities are fed with anti-phase signals, the signal size is U2 measured by sampling from the gap on the left side of the RF accelerating cavity 2, which is specifically as follows: when the RF accelerating cavities 1 and 3 are fed with high-frequency signals with anti-phase to the RF accelerating cavity 2, an electric field with the same direction as itself is formed in the RF accelerating cavity 2, that is, at this time, the electric field strength of the left gap of the RF accelerating cavity 2 is E2+E1+E3, where E1, E2, and E3 represent the electric fields formed by the RF accelerating cavities 1, 2, and 3, and their sizes are different, and E2 is greater than E1 and E3; the signal size measured by sampling from port 4 is U2=E2+E1+E3;

[0050] It should be emphasized that the above specific embodiments are merely explanations of the present invention, and they are not limitations of the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without any creative contribution as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series, characterized in that: The following steps are involved: Step 1: Assume that the number of the plurality of RF acceleration cavities connected in series is three, and the feeding ports of the three RF acceleration cavities from left to right are respectively set as port 1, port 2, and port 3, and the sampling port of the second RF acceleration cavity in the middle is set as port 4; Step 2: Taking the middle RF accelerating cavity as an example, when the three RF accelerating cavities are arranged in series, when the electric fields generated in the adjacent RF accelerating cavities on both sides leak into the middle RF accelerating cavity, the influence on the accelerating electric field of the middle RF accelerating cavity itself is obtained: |U1-U3| / U3 and |U2-U3| / U3; Step 3. If the influence is less than 1%, it is considered that the degree of mutual interference between the electric fields of adjacent cavities during the actual operation of the ion implantation system can be ignored; if the ratio is larger, it is necessary to improve the cavity or mechanical structure and conduct further research.

2. According to claim 1, a method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series, characterized in that: The specific process of step 2 is as follows: 1) Use three power sources to feed the same power to the three cavities respectively, and the phases of the three cavities are the same. When the electric field generated by the RF accelerating cavity 1 and the RF accelerating cavity 3 leaks to the middle RF accelerating cavity 2, the signal size U1 is measured by sampling from the left gap or the right gap of the RF accelerating cavity 2; 2) Use three power sources to feed the same power to the three cavities respectively, where RF accelerating cavities 1 and 3 are in anti-phase with RF accelerating cavity 2. When the electric field generated by RF accelerating cavity 1 and RF accelerating cavity 3 leaks to the middle RF accelerating cavity 2, the signal size measured by sampling from the left gap or the right gap of RF accelerating cavity 2 is U2; 3) Only one power source is used to feed the same power as before into the RF acceleration cavity 2, and the signal size measured from the port 4 is U3 (E2); 4) Calculate the size of |U1-U3| / U3 and |U2-U3| / U3.

3. According to claim 2, a method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series, characterized in that: In the process 1) of step 2), when the three RF accelerating cavities are fed with the same-phase signal, the signal size U1 is measured by sampling from the left gap of the RF accelerating cavity 2, which is specifically as follows: when the three cavities are fed with the same-phase signal, in addition to the electric field E2 in the left direction, there will also be an electric field E1 in the right direction leaked from cavity 1, and there will also be an electric field E3 in the right direction leaked from cavity 3; that is, when RF accelerating cavity 1 and RF accelerating cavity 3 are fed with high-frequency signals in phase with cavity 2, an electric field in the opposite direction to itself will be formed in RF accelerating cavity 2; that is, at this time, the electric field strength of the left gap of cavity 2 is E2-E1-E3, and the signal size U1=E2-E1-E3 is measured by sampling from port 4.

4. According to claim 2, a method for studying the electric field interference degree when multiple radio frequency accelerating cavities are connected in series, characterized in that: In the step 2 process 2), when the three RF accelerating cavities are fed with anti-phase signals, the signal size is measured by sampling from the left gap of RF accelerating cavity 2 as U2, which is as follows: when RF accelerating cavities 1 and 3 are fed with high-frequency signals with anti-phase to RF accelerating cavity 2, an electric field with the same direction as itself will be formed in RF accelerating cavity 2, that is, at this time, the electric field strength of the left gap of RF accelerating cavity 2 is E2+E1+E3, E1, E2, and E3 represent the electric fields formed by RF accelerating cavities 1, 2, and 3, and their sizes are different, and E2 is greater than E1 and E3; the signal size measured by sampling from port 4 is U2=E2+E1+E3.

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