Cathode analog converter for signal transmission efficiency testing and method of using same

Abstract

The present application belongs to the technical field of microwave grid control electron gun, and relates to a cathode analog converter for signal transmission efficiency test and a use method thereof, 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 outer layer of the cathode connector is provided with the grid connector, the filament connector, the cathode connector and the grid connector are coaxially arranged, the input ends thereof are connected with the filament, the cathode and the grid of the microwave grid control electron gun respectively, the output ends thereof are connected with the N-type connector, and the signal transmission efficiency is detected through the N-type connector. The present application can be tested offline, does not need to install the microwave grid control electron gun in the actual use environment, can detect the signal transmission efficiency without vacuumizing, greatly reduces the test time length of the electron gun feeder, reduces the use time length of the cathode-grid assembly, and saves the relevant economic cost.

Description

Technical Field

[0001] This invention relates to a cathode analog converter for signal transmission efficiency testing and its usage method, belonging to the field of microwave grid-controlled electron gun technology. Background Technology

[0002] In recent years, microwave grid-controlled electron guns have been widely used in various microwave electron accelerators. Due to their simple design, small footprint, and low cost, this type of electron gun has gradually become an important research direction for novel high-current microwave electron sources. Currently, most mainstream grid-controlled electron guns employ a method of placing the grid at a very short distance from the emitting surface of a barium-tungsten hot cathode.

[0003] In this type of cathode-grid assembly, the filament heats the cathode, generating free electrons. The emission of these free electrons is controlled by a grid voltage located very close to the emitting surface, acting as a switch. When the grid voltage is positive relative to the cathode emitting surface, electrons are emitted; when the grid voltage is negative relative to the cathode emitting surface, electrons are cut off. Microwave grid-controlled electron guns utilize this principle, transmitting microwave signals to the grid to modulate the electron beam. The tail of this type of cathode-grid assembly typically has a three-layer coaxial structure: from the inside out, a heating filament current input connector, a cathode end connector (since the filament is in direct contact with the cathode emitting surface, the cathode end connector also serves as the heating filament current output connector), and a grid control signal transmission connector.

[0004] Typically, designing a microwave grid-controlled electron gun requires testing the signal transmission efficiency of its RF signal feeder. However, since the cathode grating assembly can only operate in a high vacuum environment, it is impossible to perform offline reliability testing on the designed RF signal feeder. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a cathode analog converter and its method of use for signal transmission efficiency testing, which eliminates the need to install the microwave grid-controlled electron gun in the actual operating environment and allows for offline testing of signal transmission efficiency without the need for vacuuming.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: a cathode analog converter for signal transmission efficiency testing, comprising: a filament connector, a cathode connector, a grid connector, and an N-type connector. The filament connector is disposed in the cathode connector, and the grid connector is disposed on the outer layer of the cathode connector. The filament connector, cathode connector, and grid connector are coaxially arranged. The input ends of the filament connector, cathode connector, and grid connector are respectively connected to the filament, cathode, and grid of a microwave grid-controlled electron gun. The output ends of the filament connector, cathode connector, and grid connector are all connected to the N-type connector, and the signal transmission efficiency is detected through the N-type connector.

[0007] Furthermore, the N-type connector comprises, from the inside out, an N-type connector inner core, an N-type connector inner shielding layer, and an N-type connector outer shielding and tightening layer. The N-type connector inner core is connected to the filament connector, the N-type connector inner shielding layer is connected to the cathode connector, and the N-type connector outer shielding and tightening layer is sleeved on the N-type connector inner shielding layer.

[0008] Furthermore, the outer shield and screw-on layer of the N-type connector are at the same potential as the inner shield of the N-type connector, and the outer shield and screw-on layer of the N-type connector are in direct contact with the grid connector, forming a radio frequency signal receiving space composed of the inner shield of the N-type connector and the inner core of the N-type connector.

[0009] Furthermore, the filament connector and cathode connector are used for DC signal transmission, and the filament connector and cathode connector are short-circuited to form interconnected electrodes.

[0010] Furthermore, the cathode connector and the inner core of the N-type connector are integrally formed. The cathode connector is a hollow tubular structure. The filament connector is detachably fixed inside the tubular structure of the cathode connector. The inner core of the N-type connector is located at the end of the cathode connector opposite to the filament connector.

[0011] Furthermore, the inner shielding layer of the N-type connector is integrally formed with the grid connector, and the inner shielding layer of the N-type connector is a stepped tube with different inner diameters, wherein the inner diameter of the grid connector is larger than the maximum inner diameter of the inner shielding layer of the N-type connector.

[0012] Furthermore, an insulating medium is filled between the cathode connector and the grid connector to ensure microwave transmission within the space between the cathode connector and the grid connector and the structural strength of the space.

[0013] Furthermore, the insulating medium is polytetrafluoroethylene.

[0014] Furthermore, the cathode analog converter is connected to the network analyzer via an RF cable.

[0015] This invention also discloses a method for using a cathode analog converter for signal transmission efficiency testing, comprising: outputting a signal from the output terminal of a network analyzer, the signal being input to the feeder via the RF input port of the feeder; the output signal of the feeder being transmitted after DC blocking and then entering the microwave grid-controlled electron gun signal, and being simulated by the cathode analog converter for signal transmission efficiency testing as described above; the output signal of the cathode analog converter being input to the input terminal of the network analyzer via an RF cable to complete the offline test.

[0016] The technical solution of this invention has at least the following technical effects or advantages: The solution of this invention allows for offline testing, eliminating the need to install the microwave grid-controlled electron gun in the actual operating environment and eliminating the need for vacuuming to test its signal transmission efficiency. This significantly reduces the testing time of such electron gun feeders and also reduces the usage time of the cathode grating assembly, saving related economic costs. This enables this type of electron gun to have wider applications in fields such as nuclear technology and is more beneficial to the widespread application of electron accelerators. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a cathode analog converter used for testing the signal transmission efficiency of a microwave grid-controlled electron gun in one embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of one side of the filament connector, cathode connector, and grid connector in a cathode analog converter according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of one side of the N-type connector in a cathode analog converter according to an embodiment of the present invention.

[0020] Figure label:

[0021] 1-Filament connector; 2-Cathode connector; 3-Grid connector; 4-Isolation medium; 5-Outer shield and tightening layer of N-type connector; 6-Inner shielding layer of N-type connector; 7-Inner core of N-type connector. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for a better understanding of the present invention and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In existing technologies, microwave grid-controlled electron guns require testing the signal transmission efficiency of their RF signal feeders. However, cathode gratings, which can only operate in high-vacuum environments, cannot be used for offline reliability testing of the designed RF signal feeders. Instead, the DC blocker must be assembled with the cathode grating and installed on the electron gun and other devices for online testing via emitted electron beams. This necessitates vacuuming with a pump unit for each test, which shortens the cathode grating's lifespan. To address these issues, this invention proposes a cathode analog converter and its usage method for testing the signal transmission efficiency of microwave grid-controlled electron guns. Through coaxial structure design and impedance matching, it combines the geometry of the cathode grating's three-stage signal connector with the commonly used N-type signal transmission connector structure to simulate the actual cathode grating structure. The three layers of the cathode grating are configured separately. The grid connector of the analog converter is connected to the inner shielding layer of the N-type connector, and the filament and cathode connectors are connected to the inner core of the N-type connector. A dielectric such as polytetrafluoroethylene is filled between the inner core and the inner shielding layer of the N-type connector, enabling the transmission of RF signals within the space formed by the inner core and the inner shielding layer of the N-type connector. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] Example 1

[0025] This embodiment discloses a cathode analog converter for testing the signal transmission efficiency of a microwave grid-controlled electron gun, such as... Figure 1 , Figure 2 As shown, the device includes: a filament connector 1, a cathode connector 2, a grid connector 3, and an N-type connector. The filament connector 1 is disposed within the cathode connector 2, and the grid connector 3 is disposed on the outer layer of the cathode connector 2. The filament connector 1, cathode connector 2, and grid connector 3 are coaxially arranged. The input terminals of the filament connector 1, cathode connector 2, and grid connector 3 are respectively connected to the filament, cathode, and grid of the microwave grid-controlled electron gun. The output terminals of the filament connector 1, cathode connector 2, and grid connector 3 are all connected to the N-type connector, through which the signal transmission efficiency is detected. In this embodiment, the cathode side follows the actual dimensions of the three connectors at the tail of a real cathode converter. The filament connector 1 imitates the actual filament connector size, the cathode connector 2 imitates the actual cathode connector size, and the grid connector 3 imitates the actual grid connector size, enabling the DC blocking feeder under test to be smoothly connected to the cathode analog converter in this embodiment.

[0026] like Figure 3 As shown, the N-type connector, from the inside out, includes an inner core 7, an inner shielding layer 6, and an outer shielding and tightening layer 5. The inner core 7 connects to the filament connector 1, the inner shielding layer 6 connects to the cathode connector 2, and the outer shielding and tightening layer 5 is fitted onto the inner shielding layer 6, allowing the N-type connector to be directly connected to a signal transmission efficiency testing device. In this embodiment, the signal transmission efficiency is tested using a network analyzer, but this is not a limitation.

[0027] The outer shield and screw-on layer 5 of the N-type connector are at the same potential as the inner shield layer 6 of the N-type connector. The outer shield and screw-on layer 5 of the N-type connector are in direct contact with the grid connector 3, forming a radio frequency signal receiving space composed of the inner shield layer 6 and the inner core 7 of the N-type connector. The radio frequency signal between the cathode connector 2 and the grid connector 3 is transmitted to this radio frequency signal receiving space to achieve the purpose of radio frequency signal transmission conversion.

[0028] The cathode connector 2 and the N-type connector inner core 7 are integrally formed. The cathode connector 2 is a hollow tubular structure. The filament connector 1 is detachably fixed inside the tubular structure of the cathode connector 2. The N-type connector inner core 7 is located at one end of the cathode connector 2 opposite to the filament connector 1. That is, the cathode connector 2 is tubular and includes both ends. If the filament connector 1 is located at one end of the cathode connector 2, then the N-type connector inner core 7 is located at the other end of the cathode connector 2.

[0029] The inner shielding layer 6 of the N-type connector and the grid connector 3 are integrally formed. The inner shielding layer 6 of the N-type connector is a stepped tube with different inner diameters. The inner diameter of the grid connector 3 is larger than the maximum inner diameter of the inner shielding layer 6 of the N-type connector.

[0030] In the actual operation of the cathode assembly, filament connector 1 and cathode connector 2 are used for DC signal transmission and are not related to radio frequency signals. Filament connector 1 and cathode connector 2 are short-circuited to form interconnected electrodes and are directly connected to the inner core 7 of the N-type connector.

[0031] An insulating medium 4 is filled between the cathode connector 2 and the grid connector 3 to ensure microwave transmission and structural strength within the space between them. In this embodiment, the insulating medium 4 is polytetrafluoroethylene (PTFE).

[0032] Example 2

[0033] Based on the same inventive concept, this embodiment discloses a method for using a cathode analog converter to test the signal transmission efficiency of a microwave grid-controlled electron gun, used to detect the signal transmission efficiency of an RF signal feeder, including the following steps:

[0034] The network analyzer outputs a signal, which is then input into the feeder via the feeder's RF input port.

[0035] The output signal of the feeder is transmitted after DC blocking and then enters the microwave grating electron gun signal, and is simulated by a cathode analog converter for microwave grating electron gun signal transmission efficiency testing as described above.

[0036] The output signal from the cathode analog converter is input to the network analyzer via an RF cable to complete the offline test.

[0037] Such feeders often operate at a normal 0V potential at their RF signal input, while their output needs to operate at a high voltage of tens of kilovolts. They cannot be transmitted using standard RF cables; instead, the high voltage backlash must be isolated from the 0V RF signal during transmission. However, DC-blocking RF feeders cause signal attenuation during the feeding process. Therefore, the signal transmission efficiency is typically determined by measuring the number of electrons emitted by the cathode after connecting the feeder to a real cathode grating assembly. However, real cathode grating assemblies are expensive and require constant pumping to maintain a vacuum environment, resulting in wasted resources. In this embodiment, by designing a cathode analog converter, the signal input terminal of the feeder is connected to the signal output terminal of the network analyzer, then the signal output terminal of the feeder is connected to the input terminal of the cathode analog converter, and finally the signal output terminal of the cathode analog converter is connected to the signal input terminal of the network analyzer. This enables the network analyzer to perform spectral measurement of the signal transmission efficiency of the feeder and the cathode analog converter. Since the transmission efficiency of the cathode analog converter adopts impedance matching technology and coaxial transmission structure, and the transmission loss is a constant value, the transmission efficiency of the feeder can be calculated by the difference between the sum of the transmission efficiencies of the feeder and the cathode analog converter and the transmission efficiency of the cathode analog converter. This achieves the goal of measuring the feeder transmission efficiency without using a real cathode grid component.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific embodiments of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention. The above content is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims

1. A cathode analog converter for signal transmission efficiency testing, characterized in that, include: The device includes a filament connector, a cathode connector, a grid connector, and an N-type connector. The filament connector is disposed within the cathode connector, and the grid connector is disposed on the outer layer of the cathode connector. The filament connector, cathode connector, and grid connector are coaxially arranged. The input ends of the filament connector, cathode connector, and grid connector are respectively connected to the filament, cathode, and grid of the microwave grid-controlled electron gun. The output ends of the filament connector, cathode connector, and grid connector are all connected to the N-type connector. The signal transmission efficiency is detected through the N-type connector. The N-type connector comprises, from the inside out, an N-type connector inner core, an N-type connector inner shielding layer, and an N-type connector outer shielding and tightening layer. The N-type connector inner core is connected to the filament connector, the N-type connector inner shielding layer is connected to the cathode connector, and the N-type connector outer shielding and tightening layer is sleeved on the N-type connector inner shielding layer. The outer shield and screw-on layer of the N-type connector are at the same potential as the inner shield of the N-type connector. The outer shield and screw-on layer of the N-type connector are in direct contact with the grid connector, forming a radio frequency signal receiving space composed of the inner shield of the N-type connector and the inner core of the N-type connector.

2. The cathode analog converter for signal transmission efficiency testing as described in claim 1, characterized in that, The filament connector and cathode connector are used for DC signal transmission, and the filament connector and cathode connector are short-circuited to form interconnected electrodes.

3. The cathode analog converter for signal transmission efficiency testing as described in claim 2, characterized in that, The cathode connector and the inner core of the N-type connector are integrally formed. The cathode connector is a hollow tubular structure. The filament connector is detachably fixed inside the tubular structure of the cathode connector. The inner core of the N-type connector is located at the end of the cathode connector opposite to the filament connector.

4. The cathode analog converter for signal transmission efficiency testing as described in claim 3, characterized in that, The inner shielding layer of the N-type connector is integrally formed with the grid connector. The inner shielding layer of the N-type connector is a stepped tube with different inner diameters, and the inner diameter of the grid connector is larger than the maximum inner diameter of the inner shielding layer of the N-type connector.

5. The cathode analog converter for signal transmission efficiency testing as described in claim 1, characterized in that, The space between the cathode connector and the grid connector is filled with an insulating medium to ensure microwave transmission within the space between the cathode connector and the grid connector and the structural strength of the space.

6. The cathode analog converter for signal transmission efficiency testing as described in claim 5, characterized in that, The isolation medium is polytetrafluoroethylene.

7. The cathode analog converter for signal transmission efficiency testing as described in claim 1, characterized in that, The cathode analog converter is connected to the network analyzer via an RF cable.

8. A method for using a cathode analog converter for signal transmission efficiency testing, characterized in that, include: The network analyzer outputs a signal, which is input to the feeder through the feeder's RF input port. The output signal of the feeder is transmitted after DC blocking and then enters the microwave grid-controlled electron gun signal, and is simulated by the cathode analog converter for signal transmission efficiency testing as described in any one of claims 1-7. The output signal from the cathode analog converter is input to the network analyzer via an RF cable to complete the offline test.

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