A screening method and apparatus for a traveling wave tube electron gun cathode

Abstract

The application belongs to the technical field of traveling wave tubes, and particularly provides a screening method and equipment for a traveling wave tube electron gun cathode, which comprises the following steps: placing a traveling wave tube after assembly in a vacuum chamber; supplying power to the electron gun of the traveling wave tube by a power supply, and adjusting the power supply to gradually increase the actual working voltage of the cathode; measuring and obtaining the cathode current value of the electron gun, and obtaining the cathode current density by using the cathode current value of the electron gun and the cathode emission area; establishing the corresponding relationship between the actual working voltage and the cathode current density, and calculating the change rate of the cathode current density; when the change rate of the cathode current density is greater than a set value, recording the actual working voltage U1 at this time; calculating the difference ΔU between the actual working voltage U1 and a set working voltage U2; and when ΔU is greater than ΔU a , determining that the electron emission performance of the electron gun cathode in the tested traveling wave tube meets the set requirements. The application is convenient for simulating an electron gun with cathode electron emission performance meeting the requirements by using a smaller voltage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of traveling wave tubes, and particularly provides a screening method and device for a cathode of a traveling wave tube electron gun. BACKGROUND

[0002] The traveling wave tube electron gun is one of the core components of the traveling wave tube, and mainly consists of a cathode, an anode and a bunching system. The working principle is that a high voltage electric field is applied to the cathode to emit an electron stream, which is subjected to the bunching effect of the bunching system to form a high-speed and dense electron beam, which then enters the microwave cavity of the traveling wave tube to interact with the microwave to produce amplification, frequency conversion, modulation and the like. In the traveling wave tube electron gun, the quality and performance of the cathode directly affect the performance of the entire traveling wave tube; for the traveling wave tube electron gun, it needs to provide an electron stream with a current density greater than a set current density within a set voltage range; otherwise, it is determined that the current emission capability of the traveling wave tube electron gun is poor.

[0003] However, in the actual screening process of the traveling wave tube electron gun, the vacuum degree of the vacuum equipment cannot reach the actual vacuum degree of the traveling wave tube working in space due to the influence of the vacuum extraction equipment; generally, the vacuum degree can reach 5*10^-5 Pa in the ground simulation; that is, there is still gas residue in the vacuum chamber.

[0004] The inventor understands that, in the case that the vacuum degree cannot meet the actual working requirement, the cathode voltage of the traveling wave tube electron gun is increased to the actual working voltage in orbit, which is easy to affect the use precision and service life of the traveling wave tube; and if the cathode voltage is not increased to the actual working voltage in orbit in the screening process, it is difficult to measure whether the current density of the cathode emitted electron stream meets the requirement. SUMMARY

[0005] The purpose of the present application is to provide a screening method and device for a cathode of a traveling wave tube electron gun to at least solve one of the above technical problems.

[0006] In order to solve the above problems in the prior art, one or more embodiments of the present application provide a screening method for a cathode of a traveling wave tube electron gun, comprising the following steps: placing the traveling wave tube after being assembled in a vacuum chamber;

[0007] Connecting each lead wire of the electron gun to the power supply through a wire, the power supply supplies power to the electron gun of the traveling wave tube, and adjusting the power supply to gradually increase the actual working voltage of the cathode;

[0008] Measuring the current at the cathode lead wire of the electron gun to obtain the cathode current value of the electron gun, and obtaining the cathode current density by using the cathode current value of the electron gun and the cathode emission area;

[0009] Record the corresponding cathode current value under different actual working voltage conditions, establish the corresponding relationship between the actual working voltage and the cathode current density, and calculate the change rate of the cathode current density;

[0010] When the change rate of the cathode current density is greater than a set value, record the actual working voltage U1 at this time;

[0011] Calculate the difference ΔU between the actual working voltage U1 and the set working voltage U2;

[0012] When ΔU is greater than a preset ΔU a , it is determined that the electron emission performance of the electron gun cathode of the tested traveling wave tube meets the set requirement; otherwise, it does not meet the requirement.

[0013] One or more embodiments of the present application also provide a screening device for a traveling wave tube electron gun, comprising:

[0014] A vacuum device having a vacuum chamber;

[0015] A workbench for supporting and positioning the traveling wave tube electron gun;

[0016] A power supply for supplying power to the traveling wave tube electron gun;

[0017] A sensor assembly for measuring the voltage of the electron gun cathode and the current of the cathode;

[0018] A controller for receiving the voltage value of the electron gun cathode and the current value of the cathode, the controller being capable of obtaining the cathode current density according to the current value of the cathode and the pre-stored cathode emission area; the controller being capable of obtaining ΔU according to a preset program, and determining whether the electron emission performance of the traveling wave tube cathode electron gun meets the requirement according to the size relationship between ΔU and ΔU a .

[0019] The beneficial effects of one or more technical solutions above are:

[0020] In this scheme, the characteristic that the electron current of the cathode will increase significantly after exceeding a certain voltage value during the process of gradually increasing the cathode voltage in the traveling wave tube electron gun to approach the actual on-orbit working voltage is utilized; the change rate of the cathode current density relative to the cathode voltage is monitored in real time during the screening process, and when the change rate of the cathode current density is greater than a set value, the performance of the electron emission of the electron gun cathode is determined by judging the value of the actual cathode voltage at this time; if the cathode can emit an electron current with a current density meeting the requirement under a smaller actual cathode voltage, it is determined that the quality of the cathode meets the requirement; otherwise, it does not meet the requirement.

[0021] That is, in the present scheme, the performance of the cathode is characterized by testing the inflection point of the electron flow of the cathode in the traveling wave tube electron gun; and the influence on the precision and service life of the electron gun is avoided when the electron gun is loaded to the on-orbit working voltage under the condition that the vacuum degree does not meet the requirements. BRIEF DESCRIPTION OF DRAWINGS

[0022] Some embodiments of the present application will be described below with reference to the accompanying drawings, in which:

[0023] Figure 1 is a flowchart of the screening method in the embodiments of the present application. DETAILED DESCRIPTION

[0024] Those skilled in the art should understand that the embodiments described below are only preferred embodiments of the present application, which are only used to explain the technical principles of the present application, and are not used to limit the protection scope of the present application.

[0025] It should be noted that in the description of the present application, the terms "center", "upper", "lower", "top", "bottom", "vertical", "horizontal", "inner", "outer", and the like indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and is not intended to indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0026] In addition, it should also be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0027] As Figure 1 shown, a typical embodiment of the present application provides a screening method for a traveling wave tube electron gun cathode, comprising the following steps: placing the assembled traveling wave tube in a vacuum chamber;

[0028] Connecting each lead of the electron gun to the power supply through a wire, the power supply supplies power to the electron gun of the traveling wave tube, and adjusting the power supply to gradually increase the actual working voltage of the cathode;

[0029] Measuring the current at the cathode lead of the electron gun to obtain the cathode current value of the electron gun, and obtaining the cathode current density using the cathode current value of the electron gun and the cathode emission area;

[0030] record the corresponding cathode current value under different actual working voltage conditions, establish the corresponding relationship between the actual working voltage and the cathode current density, and calculate the change rate of the cathode current density;

[0031] When the change rate of the cathode current density is greater than a set value, record the actual working voltage U1 at this time;

[0032] Calculate the difference ΔU between the actual working voltage U1 and the set working voltage U2;

[0033] When ΔU is greater than a preset ΔU a , it is determined that the electron emission performance of the cathode of the tested traveling wave tube meets the set requirements; otherwise, it does not meet the requirements.

[0034] For the traveling wave tube electron gun, the current density of the cathode electron emission current is related to the working voltage of the cathode and the temperature of the cathode; as the cathode voltage gradually increases, the current density of the emitted electron current also increases; the corresponding relationship between the cathode voltage and the cathode current density is established, and the voltage-current density characteristic curve obtained in this way has the horizontal coordinate representing the voltage value and the vertical coordinate representing the current density; in this characteristic curve, as the voltage gradually increases, the current density first increases slowly, and then changes suddenly at a certain voltage value, and increases significantly; the mutation point represents that the cathode of the electron gun enters the best performance interval; in this interval, the increase of the voltage will cause the current density to increase by a large value. When the traveling wave tube is working in orbit, the actual working voltage of the cathode is in the best performance interval.

[0035] The purpose of the above embodiment is to obtain the voltage value at which the current density of the cathode of the traveling wave tube electron gun suddenly changes through simulation in a non-absolute vacuum on the ground; and to judge the current emission performance of the cathode of the traveling wave tube according to the size of the voltage value. If the voltage value is low, it indicates that the cathode can emit an electron current with sufficient current density at a low working voltage, and its performance is better; otherwise, it does not meet the use requirements.

[0036] In this embodiment, after the traveling wave tube is placed in the vacuum chamber, the vacuum chamber is evacuated to a vacuum degree of 5x10^-5 Pa.

[0037] In this embodiment, each lead of the electron gun is a cathode lead, a hot sub-lead, a first anode lead, a second anode lead and a focusing and collecting lead, the first anode lead and the second anode lead are respectively in communication with the negative pole of the power supply, and the cathode lead and the focusing and collecting lead are respectively in communication with the positive pole of the power supply.

[0038] In the embodiment, when the power supply supplies power to the electron gun of the traveling wave tube, the infrared thermometer is used to measure the temperature of the electron gun cathode, and the correspondence between the real-time temperature of the cathode and the cathode current density is recorded; if the real-time temperature of the cathode is greater than the set threshold, the test is stopped.

[0039] One or more embodiments of the present application also provide a screening device for a traveling wave tube electron gun cathode, which is used for the above-mentioned screening method for a traveling wave tube electron gun cathode, and includes a vacuum device, a workbench, a power supply, a sensor assembly, and a controller.

[0040] The vacuum device has a vacuum chamber; the workbench is used to realize the support and positioning of the traveling wave tube electron gun;

[0041] The power supply is used to supply power to the traveling wave tube electron gun; the sensor assembly is used to measure the voltage of the electron gun cathode and the current of the cathode; the controller is used to receive the voltage value of the electron gun cathode and the current value of the cathode, the controller can obtain the cathode current density according to the current value of the cathode and the pre-stored cathode emission area; the controller can obtain ΔU according to the preset program, and judge whether the electron flow emission performance of the traveling wave tube cathode electron gun meets the requirements according to the size relationship between ΔU and the pre-set ΔU a .

[0042] In the embodiment, the workbench has a flange plate, the flange plate has a plurality of through holes, and the through holes are respectively used to accommodate and position the lead wires of the traveling wave tube electron gun.

[0043] In the embodiment, the vacuum device has a vacuum pumping assembly for pumping the vacuum chamber.

[0044] In the embodiment, the power supply is integrated in the workbench.

[0045] In the embodiment, the power supply has a current sensor and a voltage sensor integrated therein, the current sensor can measure the current of the electron gun cathode, and the voltage sensor can measure the real-time working voltage of the electron gun cathode.

[0046] In the embodiment, the vacuum device is provided with an infrared thermometer for measuring the temperature of the traveling wave tube electron gun cathode.

[0047] So far, the technical solutions of the present application have been described in combination with the foregoing preferred embodiments, but those skilled in the art can easily understand that the protection scope of the present application is not limited to the foregoing preferred embodiments. Those skilled in the art can split and combine the technical solutions in the foregoing preferred embodiments, or make equivalent changes or replacements to the related technical features, without departing from the technical principles of the present application. Any changes, equivalent replacements, improvements, etc. made within the technical concept and / or technical principles of the present application will fall within the protection scope of the present application.

Claims

1. A screening method for a traveling wave tube electron gun cathode, characterized by, The method comprises the following steps: After the TWT is assembled, the TWT is placed in a vacuum chamber; Each lead wire of the electron gun is connected to a power supply through a wire, and the power supply supplies power to the electron gun of the TWT, and the actual working voltage of the cathode is gradually increased by adjusting the power supply; The current at the cathode lead wire of the electron gun is measured, and then the cathode current value of the electron gun is obtained, and the cathode current density is obtained by using the cathode current value of the electron gun and the cathode emission area; The corresponding cathode current value under different actual working voltages is recorded, the corresponding relationship between the actual working voltage and the cathode current density is established, and the change rate of the cathode current density is calculated; When the change rate of the cathode current density is greater than a set value, the actual working voltage U1 at this time is recorded; The actual working voltage U1 and the set working voltage U2 are subtracted to obtain the difference ΔU. When △U is greater than the preset △U a , it is determined that the electron emission performance of the electron gun cathode of the tested traveling wave tube meets the set requirement; otherwise, it does not meet the requirement.

2. The method of claim 1, wherein the method is characterized by: After the TWT is placed in the vacuum chamber, the vacuum chamber is evacuated to a vacuum degree of 5*10^-5 Pa.

3. The method of claim 1, wherein the method is used for screening a cathode for an electron gun of a traveling wave tube, and the method further comprises: providing a plurality of cathodes; and selecting a cathode from the plurality of cathodes based on the measured value of the cathode. Each lead wire of the electron gun is a cathode lead wire, a hot lead wire, a first anode lead wire, a second anode lead wire and a focusing lead wire, the first anode lead wire and the second anode lead wire are in communication with the negative pole of the power supply, and the cathode lead wire and the focusing lead wire are in communication with the positive pole of the power supply.

4. The screening method for the cathode of a traveling wave tube electron gun according to claim 1, characterized in that, When the power supply supplies power to the electron gun of the TWT, the temperature of the cathode of the electron gun is measured by using an infrared thermometer, and the corresponding relationship between the real-time temperature of the cathode and the cathode current density is recorded; if the real-time temperature of the cathode is greater than a set threshold, the test is stopped.

5. A screening apparatus for a traveling wave tube electron gun cathode, for implementing the screening method for a traveling wave tube electron gun cathode according to any one of claims 1 to 4, characterized by It comprises: a vacuum device having a vacuum chamber; a workbench for supporting and positioning the TWT electron gun; a power supply for supplying power to the TWT electron gun; a sensor assembly for measuring the voltage of the cathode of the electron gun and the current of the cathode; a controller for receiving the voltage value of the cathode of the electron gun and the current value of the cathode, and the controller can obtain the cathode current density according to the current value of the cathode and the pre-stored cathode emission area; The controller can obtain △U according to a preset program, and determine whether the electron flow emission performance of the cathode electron gun of the traveling wave tube meets the requirements according to the size relationship between △U and △U a .

6. The screen apparatus for a traveling wave tube electron gun cathode according to claim 5, characterized by, The workbench has a flange plate with a plurality of through holes for accommodating and positioning the lead wires of the TWT electron gun.

7. The screen apparatus for a traveling wave tube electron gun cathode according to claim 5, characterized by, The vacuum device has a vacuum assembly for evacuating the vacuum chamber.

8. The screen apparatus for a traveling wave tube electron gun cathode according to claim 5, characterized by, The workbench integrates the power supply.

9. The screen apparatus for a traveling wave tube electron gun cathode according to claim 5, characterized by, The power supply integrates a current sensor and a voltage sensor, the current sensor can measure the current of the cathode of the electron gun, and the voltage sensor can measure the real-time working voltage of the cathode of the electron gun.

10. The screen apparatus for a traveling wave tube electron gun cathode according to claim 5, characterized by, The vacuum device is provided with an infrared thermometer for measuring the temperature of the cathode of the TWT electron gun.

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