Cathode analog converter for testing signal transmission efficiency and use method thereof

Abstract

The invention belongs to the technical field of microwave grid-control electron guns, and relates to a cathode analog converter for testing signal transmission efficiency and a use method thereof.The cathode analog converter comprises a filament connector, a cathode connector, a grid connector and an N-type connector, the filament connector is arranged in the cathode connector, the grid connector is arranged on the outer layer of the cathode connector, and the N-type connector is arranged on the outer layer of the cathode connector; the filament connector, the cathode connector and the grid connector are coaxially arranged, the input ends of the filament connector, the cathode connector and the grid connector are respectively connected with a filament, a cathode and a grid of the microwave grid-controlled electron gun, the output ends of the filament connector, the cathode connector and the grid connector are connected with the N-type connector, and the signal transmission efficiency is detected through the N-type connector. According to the invention, off-line detection can be carried out, the microwave grid-controlled electron gun does not need to be installed in an actual use environment, the signal transmission efficiency of the microwave grid-controlled electron gun can be detected without vacuum pumping, the problem of long test time of the electron gun feed-in device is greatly reduced, the use time of the cathode grid assembly is reduced, and related economic cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to a cathode simulation converter for signal transmission efficiency test and a method thereof, and belongs to the technical field of microwave grid-controlled electron guns. BACKGROUND

[0002] In recent years, microwave grid-controlled electron guns have been widely used in various types of microwave electronic accelerators. This type of electron gun has gradually become an important research direction of new-type high-current microwave electron sources due to its simple design structure, small footprint and low cost. Currently, the mainstream grid-controlled electron gun adopts the method of placing a grid in a very short distance from the emission surface of a barium tungsten material hot cathode.

[0003] This type of cathode-grid assembly generates free electrons from a filament-heated cathode, and the emission or non-emission of free electrons is controlled by the grid voltage which is very close to the emission surface, thereby playing a switching role. When the grid voltage is positive relative to the cathode emission surface, the electrons are emitted; when the grid voltage is negative relative to the cathode emission surface, the electrons are cut off. The microwave grid-controlled electron gun uses this principle to modulate the electron beam by transmitting a microwave signal to the grid.

[0004] Generally, the signal transmission efficiency of the RF signal feed-in device of the microwave grid-controlled electron gun needs to be tested. However, as a device that can only work in a high-vacuum environment, the cathode-grid assembly cannot perform offline reliability testing on the designed RF signal feed-in device. SUMMARY

[0005] To solve the above problems, the present application provides a cathode simulation converter for signal transmission efficiency test and a method thereof, which does not need to install the microwave grid-controlled electron gun in the actual use environment, and can perform offline detection on the signal transmission efficiency without vacuumizing.

[0006] To achieve the above object, the present application provides the following technical scheme: a cathode simulation converter for signal transmission efficiency test, comprising a filament connector, a cathode connector, a grid connector and an N-type connector, the filament connector is arranged in the cathode connector, the grid connector is arranged outside the cathode connector, the filament connector, the cathode connector and the grid connector are coaxially arranged, the input ends of the filament connector, the cathode connector and the grid connector are connected with the filament, the cathode and the grid of the microwave grid-controlled electron gun, the output ends of the filament connector, the cathode connector and the grid connector are connected with the N-type connector, and the signal transmission efficiency is detected through the N-type connector.

[0007] Further, the N-type joint comprises, from inside to outside, an N-type joint inner core, an N-type joint inner shielding layer and an N-type joint outer shielding and screwing layer, the N-type joint inner core is connected with the filament joint, the N-type joint inner shielding layer is connected with the cathode joint, and the N-type joint outer shielding and screwing layer is sleeved on the N-type joint inner shielding layer.

[0008] Further, the N-type joint outer shielding and screwing layer is at the same potential as the N-type joint inner shielding layer, the N-type joint outer shielding and screwing layer is directly contacted with the grid joint, and a radio frequency signal receiving space composed of the N-type joint inner shielding layer and the N-type joint inner core is formed.

[0009] Further, the filament joint and the cathode joint are used for direct current signal transmission, and the filament joint and the cathode joint are short-circuited to form an intercommunication electrode.

[0010] Further, the cathode joint is integrally formed with the N-type joint inner core, the cathode joint is in a hollow tubular structure, the filament joint is detachably fixed in the tubular structure of the cathode joint, and the N-type joint inner core is arranged at an end of the cathode joint opposite to the filament joint.

[0011] Further, the N-type joint inner shielding layer is integrally formed with the grid joint, the N-type joint inner shielding layer is a stepped pipe with different inner diameters, and the inner diameter of the grid joint is greater than the maximum inner diameter of the N-type joint inner shielding layer.

[0012] Further, the cathode joint and the grid joint are filled with an isolation medium to ensure microwave transmission in a space between the cathode joint and the grid joint and structural strength of the space.

[0013] Further, the isolation medium is polytetrafluoroethylene.

[0014] Further, the cathode analog converter is connected with a network analyzer through a radio frequency cable.

[0015] The application further discloses a use method of the cathode analog converter for signal transmission efficiency testing, which comprises the following steps: a network analyzer outputs a signal, the signal is input into a feeder through a radio frequency input port of the feeder, the output signal of the feeder is transmitted through a direct-current isolation transmission and then enters a microwave grid control electron gun signal, and the signal is simulated through the cathode analog converter for signal transmission efficiency testing; the output signal of the cathode analog converter is input into an input end of the network analyzer through a radio frequency cable, and offline testing is completed.

[0016] The technical scheme of the present application has at least the following technical effects or advantages: the scheme in the present application can be used offline, the microwave grid control electron gun does not need to be installed in an actual use environment, the signal transmission efficiency of the electron gun can be detected without vacuumizing, the test time of the electron gun feeder is greatly reduced, the use time of the grid assembly is reduced, and the relevant economic cost is saved. The electron gun of this type can be more widely used in the field of nuclear technology, and is more conducive to the wide application of the electron accelerator. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structure diagram of a cathode analog converter for testing the signal transmission efficiency of a microwave grid control electron gun in an embodiment of the present application; Figure 2 is a structure diagram of one side of a filament joint, a cathode joint and a grid joint in the cathode analog converter in an embodiment of the present application; Figure 3 is a structure diagram of one side of an N-type joint in the cathode analog converter in an embodiment of the present application.

[0018] Reference signs: 1-filament joint; 2-cathode joint; 3-grid joint; 4-isolation medium; 5-N-type joint outer shielding and screwing layer; 6-N-type joint inner shielding layer; 7-N-type joint inner core. DETAILED DESCRIPTION

[0019] In order to make the skilled in the art better understand the technical scheme of the present application, the present application is described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for better understanding of the present application, and they should not be understood as a limitation on the present application. In the description of the present application, it should be understood that the terms used are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0020] In the prior art, the microwave grid control electron gun needs to test the signal transmission efficiency of its RF signal feeder, and the grid assembly, as a device that can only work in a high vacuum environment, cannot perform offline reliability testing on the designed RF signal feeder, and must be assembled with the direct current blocking device and installed in an electron gun or the like to perform online testing through the emission of electron beams, which results in the need for a pump group to be pumped to vacuum each time, and the service life of the grid assembly is consumed. In view of the above problems, the present application provides a cathode simulation converter for microwave grid control electron gun signal transmission efficiency testing and a use method thereof, which combines the geometric structure of the three-level connector of the grid assembly with the commonly used signal transmission N-type connector structure through coaxial structure design and impedance matching, simulates the real grid assembly structure, configures the three-layer connector of the grid assembly respectively, connects the grid mesh connector of the simulation converter with the inner shielding layer of the N-type connector, connects the filament connector and the cathode connector with the inner core of the N-type connector, fills polytetrafluoroethylene medium between the inner core and the inner shielding layer of the N-type connector, and realizes the transmission of the RF signal in the space composed of the inner core and the inner shielding layer of the N-type connector. The present application will be described in detail below with reference to the accompanying drawings.

[0021] Example 1 The present embodiment discloses a cathode simulation converter for microwave grid control electron gun signal transmission efficiency testing, as shown in Figure 1 , Figure 2 , which comprises a filament connector 1, a cathode connector 2, a grid mesh connector 3 and an N-type connector. The filament connector 1 is arranged in the cathode connector 2, the grid mesh connector 3 is arranged on the outer layer of the cathode connector 2, the filament connector 1, the cathode connector 2 and the grid mesh connector 3 are coaxially arranged, the input ends of the filament connector 1, the cathode connector 2 and the grid mesh connector 3 are connected with the filament, the cathode and the grid mesh of the microwave grid control electron gun respectively, and the output ends of the filament connector 1, the cathode connector 2 and the grid mesh connector 3 are all connected with the N-type connector. The signal transmission efficiency is detected through the N-type connector. In the present embodiment, the cathode side is in accordance with the actual size of the tail three connectors of the real cathode converter, the filament connector 1 simulates the actual filament connector size, the cathode connector 2 simulates the actual cathode connector size, and the grid mesh connector 3 simulates the actual grid mesh connector size, so that the direct current blocking feeder to be tested can be smoothly connected with the cathode simulation converter in the present embodiment.

[0022] As shown in Figure 3 , the N-type connector comprises an N-type connector inner core 7, an N-type connector inner shielding layer 6 and an N-type connector outer shielding and tightening layer 5 from inside to outside, the N-type connector inner core 7 is connected with the filament connector 1, the N-type connector inner shielding layer 6 is connected with the cathode connector 2, and the N-type connector outer shielding and tightening layer 5 is sleeved on the N-type connector inner shielding layer 6, so that the N-type connector can be directly connected with the signal transmission efficiency testing device. In the present embodiment, the signal transmission efficiency testing is detected by a network analyzer, but it is not limited thereto.

[0023] The N-type joint outer shielding and screwing layer 5 and the N-type joint inner shielding layer 6 are at the same potential, the N-type joint outer shielding and screwing layer 5 is directly contacted with the grid joint 3, and the N-type joint inner shielding layer 6 and the N-type joint inner core 7 form a radio frequency signal receiving space. The radio frequency signal between the cathode joint 2 and the grid joint 3 is transmitted to the radio frequency signal receiving space, so as to achieve the purpose of radio frequency signal transmission conversion.

[0024] The cathode joint 2 and the N-type joint inner core 7 are integrally formed, the cathode joint 2 is a hollow tubular structure, the filament joint 1 is detachably fixed in the tubular structure of the cathode joint 2, and the N-type joint inner core 7 is arranged at the end of the cathode joint 2 opposite to the filament joint 1, that is, the cathode joint 2 is tubular and includes two ends, if the filament joint 1 is arranged at one end of the cathode joint 2, the N-type joint inner core 7 is arranged at the other end of the cathode joint 2.

[0025] The N-type joint inner shielding layer 6 and the grid joint 3 are integrally formed, the N-type joint inner shielding layer 6 is a stepped tube with different inner diameters, and the inner diameter of the grid joint 3 is greater than the maximum inner diameter of the N-type joint inner shielding layer 6.

[0026] In the actual work of the cathode-grid assembly, the filament joint 1 and the cathode joint 2 are used for direct current signal transmission and are irrelevant to radio frequency signals, the filament joint 1 and the cathode joint 2 are short-circuit connected to form a mutual electrode, and the N-type joint inner core 7 is directly connected.

[0027] The isolation medium 4 is filled between the cathode joint 2 and the grid joint 3 to ensure the microwave transmission in the space between the cathode joint 2 and the grid joint 3 and the structural strength of the space. In the embodiment, the isolation medium 4 is polytetrafluoroethylene.

[0028] Embodiment two Based on the same inventive concept, the embodiment discloses a use method of a cathode analog converter for testing signal transmission efficiency of a microwave grid control electron gun, which is used for detecting the signal transmission efficiency of a radio frequency signal feeder, and includes the following steps: A network analyzer outputs a signal, and the signal is input into the feeder through a radio frequency input port of the feeder; The output signal of the feeder is transmitted through a direct current isolation transmission and then enters a microwave grid control electron gun signal, and the signal is analogized through the cathode analog converter for testing signal transmission efficiency of the microwave grid control electron gun according to any one of the above. The output signal of the cathode analog converter is input into an input end of a network analyzer through a radio frequency cable, and off-line testing is completed.

[0029] The RF signal input end of such a feeder often works at 0 potential used in normal life, and the output end needs to work at a high voltage potential of tens of kilovolts, so the RF signal cannot be transmitted by the commonly used RF cable, and the RF signal needs to be isolated from the high voltage signal back to 0 potential while transmitting the RF signal. The DC-blocking RF feeder will cause attenuation of the RF signal during the feeding process, so in general, the signal transmission efficiency of the feeder needs to be judged by connecting the feeder with the real grid assembly and actually emitting how many electrons by the cathode, and the real grid assembly is expensive and must be kept in a vacuum working environment at all times after being opened, which causes waste of resources. In the embodiment, by designing a cathode analog converter, the signal input end of the feeder is connected to the signal output end of the network analyzer, then the signal output end of the feeder is connected to the input end of the cathode analog converter, and then the signal output end of the cathode analog converter is connected to the signal input end of the network analyzer, so that the network analyzer can measure the signal transmission efficiency of the feeder and the cathode analog converter. The transmission efficiency of the cathode analog converter uses impedance matching technology and coaxial transmission structure, and the transmission loss is a constant value, so the transmission efficiency of the feeder can be calculated by the sum of the transmission efficiency of the feeder and the cathode analog converter and the difference between the transmission efficiency of the cathode analog converter, thereby achieving the purpose of measuring the transmission efficiency of the feeder without using the real grid assembly.

[0030] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it, although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered within the protection scope of the claims of the present application. The above content is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A cathode-analog converter for signal transmission efficiency testing, characterized by The application relates to a cathode analog converter for signal transmission efficiency testing. The N-type joint comprises an N-type joint inner core, an N-type joint inner shielding layer and an N-type joint outer shielding and screwing layer from inside to outside.

2. The cathode-analog converter for signal transmission efficiency test according to claim 1, wherein, The N-type joint outer shielding and screwing layer and the N-type joint inner shielding layer are at the same potential, the N-type joint outer shielding and screwing layer is directly contacted with the grid joint, and a radio frequency signal receiving space formed by the N-type joint inner shielding layer and the N-type joint inner core is formed.

3. The cathode-analog converter for signal transmission efficiency test according to claim 2, wherein, The filament joint and the cathode joint are used for direct current signal transmission, the filament joint and the cathode joint are short-circuited, and the intercommunication electrode is formed.

4. The cathode analog converter for signal transmission efficiency test of claim 2, wherein, The cathode joint is integrally formed with the N-type joint inner core, the cathode joint is a hollow tubular structure, the filament joint is detachably fixed in the tubular structure of the cathode joint, and the N-type joint inner core is arranged at one end of the cathode joint opposite to the filament joint.

5. The cathode-analog converter for signal transmission efficiency test according to claim 4, wherein, The N-type joint inner shielding layer is integrally formed with the grid joint, the N-type joint inner shielding layer is a stepped pipe with different inner diameters, and the inner diameter of the grid joint is larger than the maximum inner diameter of the N-type joint inner shielding layer.

6. The cathode analog converter for signal transmission efficiency test of claim 4, wherein, The cathode joint and the grid joint are filled with an isolation medium to ensure microwave transmission in a space between the cathode joint and the grid joint and structural strength of the space.

7. The cathode analog converter for signal transmission efficiency test of claim 1, wherein, The isolation medium is polytetrafluoroethylene.

8. The cathode analog converter for signal transmission efficiency test of claim 7, wherein, The cathode analog converter is connected with a network analyzer through a radio frequency cable.

9. The cathode analog converter for signal transmission efficiency test of claim 1, wherein, The network analyzer outputs a signal, the signal is input into a feeder through a radio frequency input port of the feeder, 10. A method of using a cathode-analog converter for signal transmission efficiency testing, characterized by, the output signal of the feeder is transmitted through a direct-current isolation transmission and then enters a microwave grid control electron gun signal, and the signal is analogized through the cathode analog converter for signal transmission efficiency testing according to any one of claims 1-9, the output signal of the cathode analog converter is input into an input end of the network analyzer through a radio frequency cable, and off-line testing is completed. ​ ​

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