A method and system for preparing an attenuator

Abstract

The present invention belongs to the technical field of space traveling wave tubes, and specifically provides a method and system for preparing an attenuator. The method for preparing the attenuator includes using a vacuum coating machine to coat a carbon film on the area to be coated in the clamping rod to form a coated area, and the actual thickness value of any point in the coated area is not lower than a preset value; axially dividing the coated area along the clamping rod into multiple sub-areas, measuring the resistance of each sub-area, and calculating the actual thickness value of the carbon film in each sub-area according to the resistance of the sub-area, the size of the clamping rod, the length of the sub-area, and the resistivity of the carbon film; comparing the actual thickness value of each sub-area with the preset value, and using laser ablation to remove the carbon film with excessive thickness.

Description

Technical Field

[0001] The present invention belongs to the technical field of space traveling wave tubes, and specifically provides a method and system for preparing an attenuator. Background Art

[0002] A traveling wave tube is a broadband high-gain device. In order to prevent oscillations caused by internal reflections, an attenuator needs to be installed inside the tube to cut off the feedback path. One type of attenuator structure is a carbon film attenuator, which forms a carbon thin film concentrated attenuator by thermally cracking compounds such as n-heptane in a vacuum and depositing carbon on a clamping rod.

[0003] The inventor has learned that in related technical solutions, in order to control the carbon film thickness of the tapered section of the attenuator, a baffle or other shielding member is set in a vacuum coating machine. The baffle is located between the evaporation source and the clamping rod. When the baffle shields a corresponding position of the clamping rod, the clamping rod cannot be coated. The thickness of the coating at that location is controlled by controlling the exposure time of the corresponding area of the clamping rod in the chamber of the vacuum coating machine.

[0004] The inventor believes that in the above technical solution, a movable shielding member needs to be set in the vacuum coating machine, and the movement of the shielding member needs to be driven by a driving mechanism. If the power source of the driving mechanism (such as an electric push rod or a rotary motor) is set in the working chamber of the vacuum coating machine, the requirements for its high-temperature resistance are relatively high, and it is prone to damage; if the power source is set outside the working chamber of the vacuum coating machine, the transmission mechanism between the power source and the shielding member will pass through the side wall of the vacuum coating machine. The movable characteristic of the transmission mechanism relative to the side wall of the vacuum coating machine increases the sealing difficulty at the side wall of the vacuum coating machine, and it is difficult to ensure the vacuum degree of the working chamber of the vacuum coating machine.

[0005] At the same time, in the above technical solution, limited by the use of the shielding mechanism, the vacuum coating machine can only complete the coating of one clamping rod at a time, which is not convenient for improving the coating efficiency of the clamping rod. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and system for preparing an attenuator to solve at least one of the above technical problems.

[0007] To solve the above problems in the prior art, one or more embodiments of the present invention provide a method for preparing an attenuator, including the following steps:

[0008] Step 1, using a vacuum coating machine to coat a carbon film on the area to be coated in the clamping rod to form a coated area, and the actual thickness value of any point in the coated area is not less than a preset value;

[0009] Step 2: Divide the coating area into multiple sub-regions along the axial direction of the clamping rod, measure the resistance of each sub-region, and calculate the actual thickness value of the carbon film in each sub-region based on the resistance of the sub-region, the outer diameter of the clamping rod, the length of the sub-region, and the resistivity of the carbon film.

[0010] Step 3: Compare the actual thickness value of each sub-region with the preset value, and use laser ablation to remove the carbon film with excessive thickness.

[0011] As a further improvement, the actual thickness of the carbon film in the sub-region calculated in Step 2 is the average thickness, and the average thickness is used to characterize the actual thickness of the carbon film in the sub-region.

[0012] As a further improvement, in Step 3, the thickness of the carbon film ablated and removed is controlled by controlling the laser ablation parameters, and the laser ablation parameters include laser power and ablation time.

[0013] As a further improvement, before Step 3, a mathematical model of the ablation thickness of the carbon film on the surface of the attenuator during laser ablation and the laser ablation parameters is established.

[0014] As a further improvement, the method for establishing the data model is as follows:

[0015] Taking the laser power as a constant value and the ablation time parameter as a variable, obtain multiple sets of carbon film thickness values before and after ablation through experiments; obtain a mathematical model characterizing the corresponding relationship between the ablation time and the ablation thickness under a unit laser power.

[0016] Taking the ablation time parameter as a constant value and the laser power as a variable, obtain multiple sets of carbon film thickness values before and after ablation through experiments; obtain a mathematical model characterizing the corresponding relationship between the laser power and the ablation thickness per unit time.

[0017] As a further improvement, measure the resistance value of the carbon film in the test area of the attenuator, and obtain the thickness of the carbon film before and after ablation through the resistance value, the length of the test area, the outer diameter of the clamping rod, and the resistivity of the carbon film.

[0018] As a further improvement, use a scanning electron microscope to measure the cross-sectional image of the attenuator to obtain the thickness of the carbon film before and after ablation.

[0019] As a further improvement, in Step 1, multiple clamping rods are coated simultaneously in the working chamber of the vacuum coating machine each time.

[0020] One or more embodiments of the present invention further provide an attenuator preparation system for implementing the above-mentioned attenuator preparation method, including:

[0021] A vacuum coating machine for accommodating the clamping rod and coating a carbon film on the area to be coated;

[0022] A resistance measurement mechanism for obtaining the resistance values of multiple sub-regions along the axial direction of the clamping rod;

[0023] A laser ablation mechanism for ablating the excess thickness of the carbon film on the surface of the clamping rod;

[0024] A controller for obtaining the actual thickness of the carbon film according to the resistance value, the preset resistivity of the carbon film and the parameters of the clamping rod, obtaining the thickness to be ablated according to the difference between the actual thickness and the preset thickness of the carbon film, and controlling the ablation parameters of the laser ablation mechanism according to the thickness to be ablated.

[0025] The beneficial effects of the above one or more technical solutions:

[0026] In this solution, the coating of the tapered section is completed in the vacuum coating machine without using a shielding member, avoiding the damage of the power source of the shielding member due to poor heat resistance, or the problem of difficult sealing caused by the power source being set outside the vacuum coating machine and unable to reach the corresponding vacuum degree.

[0027] At the same time, in this solution, after the preliminary coating of the carbon film is completed in the vacuum coating machine, laser ablation is used to change the thickness of the carbon film. The precision of laser ablation for removing the carbon film is high; it is convenient to reduce the precision requirements for coating the clamping rod at the vacuum coating machine stage, thereby saving the manufacturing cost of the attenuator.

[0028] In this solution, by axially dividing the clamping rod into multiple sub-regions, the average thickness of the carbon film in this region can be obtained through the resistance of the sub-region, the resistivity of the carbon film and the parameters of the clamping rod, which is convenient for measuring the thickness of the carbon film without damaging the already coated clamping rod.

[0029] In this solution, laser ablation is used to remove the excess carbon film on the surface of the clamping rod. Laser ablation can remove the carbon film thickness while modifying the outer surface of the carbon film, reducing the surface roughness of the carbon film and improving its surface precision.

[0030] In this solution, the resistance of the sub-region is measured, and then the average thickness of the carbon film is obtained according to the resistance of the sub-region, the outer diameter of the clamping rod, the length of the sub-region, etc. When the length of the sub-region is short, it can be used to represent the actual thickness at any point in this region; this setting method reduces the difficulty of measuring the actual thickness of the carbon film at the clamping rod.

[0031] In this solution, before the preparation of the attenuator, a mathematical model of the corresponding relationship between the ablation thickness of the carbon film on the surface of the attenuator and the laser ablation parameters is established through experiments, which is convenient for accurately adjusting the laser ablation parameters according to the required removal thickness of the carbon film.

[0032] In this solution, a laser ablation method is used to adjust the thickness of the carbon film on the surface of the clamping rod. During the laser ablation process, the moving path of the laser is easy to adjust, which is convenient for achieving a gradually changing carbon film thickness in the tapered section of the attenuator.

[0033] The attenuator preparation system in this solution consists of a vacuum coating machine, a resistance measurement mechanism, a laser ablation mechanism, and a controller. Since only the clamping rod needs to be coated in the vacuum coating machine, there is no need to precisely control the thickness of the carbon film, nor to consider the change in the carbon film thickness in the tapered section of the attenuator. Therefore, multiple clamping rods can be coated in the vacuum coating machine at one time, which is convenient for improving the utilization rate of the vacuum coating machine and the manufacturing efficiency of the attenuator, and reducing its manufacturing cost. Description of the Drawings

[0034] The following describes some embodiments of the present application with reference to the drawings, in which:

[0035] Figure 1 is a schematic flowchart of the method for preparing an attenuator in an embodiment of the present invention. Detailed Embodiments

[0036] Those skilled in the art should understand that the embodiments described below are only preferred embodiments of the present application, and the preferred embodiments are only used to explain the technical principle of the present application, rather than to limit the protection scope of the present application.

[0037] It should be noted that in the description of the present application, the terms indicating directions or positional relationships such as "center", "upper", "lower", "top", "bottom", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description, rather than indicating or implying that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0038] In addition, it should also be noted that in the description of the present application, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can also be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0039] As Figure 1 shown, a typical embodiment of the present application provides a method for preparing an attenuator, including the following steps:

[0040] Step 1: Use a vacuum coating machine to coat a carbon film on the area to be coated in the clamping rod to form a coated area, and the actual thickness value of any point in the coated area is not less than the preset value. Specifically, when using the vacuum coating machine to complete the coating of the clamping rod, it is only necessary to ensure that the actual thickness of any point in the coated area is not less than the preset value, without the need to precisely control the coating thickness, nor to consider the problem of the sequential change of the carbon film thickness at the tapered section of the attenuator; it is convenient to complete the coating of multiple clamping rods at one time in the vacuum coating machine and then transfer to the subsequent process for processing.

[0041] Step 2: Divide the coated area into multiple sub-areas along the axial direction of the clamping rod, measure the resistance of each sub-area, and calculate the actual thickness value of the carbon film in each sub-area according to the resistance of the sub-area, the dimensions of the clamping rod, the length of the sub-area, and the resistivity of the carbon film. In this embodiment, after using the vacuum coating machine to complete the coating of multiple clamping rods, since there are no specific requirements for the placement position of the clamping rods, etc., it is easy to have different carbon film thickness values in each sub-area along the axial direction of the clamping rod. Before using the laser to ablate the carbon film on the surface of the clamping rod, the average thickness of the carbon film in each sub-area is obtained in segments as the actual thickness, which is used as the basis for removing the corresponding thickness from each sub-area of the clamping rod. When the axial length of the sub-area along the clamping rod is less than the set value (for example, less than 3 mm), the difference between the actual carbon film thickness at each point in the sub-area and the average thickness value of the entire sub-area is relatively small, and the average thickness value can be used to represent the actual carbon film thickness of the sub-area.

[0042] In this embodiment, the carbon film is a good conductor, and there are many ways to measure the resistance. The simplest is the contact method, and there are also non-contact methods for measurement (eddy current method, etc.).

[0043] Step 3: Compare the actual thickness value of each sub-area with the preset value, and use the laser ablation method to remove the carbon film with excess thickness.

[0044] In one specific structural form, the laser uses a green laser, which is in the form of a laser line. The laser emitter irradiates the surface of the clamping rod as a laser line, and this laser line is parallel to the clamping rod. The clamping rod rotates along its own axis to complete the ablation of the carbon film in the circumferential direction.

[0045] Specifically, in Step 3, the thickness of the carbon film ablated and removed is controlled by controlling the laser ablation parameters. The laser ablation parameters include laser power and ablation time.

[0046] Specifically, before Step 3, a mathematical model of the ablation thickness of the carbon film on the surface of the attenuator and the laser ablation parameters is established when using laser ablation.

[0047] Specifically, the method for establishing the data model is as follows:

[0048] With the laser power being a fixed value and the ablation time parameter being a variable, multiple sets of carbon film thickness values before and after ablation are obtained through experiments; a mathematical model characterizing the corresponding relationship between the ablation time and the ablation thickness is derived under a unit laser power.

[0049] With the ablation time parameter being a fixed value and the laser power being a variable, multiple sets of carbon film thickness values before and after ablation are obtained through experiments; a mathematical model characterizing the corresponding relationship between the laser power and the ablation thickness is obtained per unit time.

[0050] Specifically, measure the resistance value of the carbon film in the test area of the attenuator, and obtain the thickness of the carbon film before and after ablation through the resistance value, the length of the test area, the outer diameter of the clamping rod, and the resistivity of the carbon film.

[0051] Specifically, use a scanning electron microscope to measure the cross-sectional image of the attenuator to obtain the thickness of the carbon film before and after ablation.

[0052] Specifically, in step 1, coating of multiple clamping rods is completed simultaneously in the working chamber of the vacuum coater each time.

[0053] This embodiment also provides an attenuator preparation system for implementing the above-mentioned attenuator preparation method, including: a vacuum coater, a resistance measurement mechanism, a laser ablation mechanism, and a controller. The vacuum coater is used to accommodate the clamping rod and coat a carbon film in the area to be coated; the resistance measurement mechanism is used to obtain the resistance values of multiple sub-regions along the axial direction of the clamping rod; the laser ablation mechanism is used to ablate the carbon film with an excessive thickness on the surface of the clamping rod; the controller is used to obtain the actual thickness of the carbon film according to the resistance value, the preset resistivity of the carbon film, and the clamping rod parameters, obtain the thickness to be ablated according to the difference between the actual thickness of the carbon film and the preset thickness, and control the ablation parameters of the laser ablation mechanism according to the thickness to be ablated.

[0054] In this embodiment, there are various structural forms of the resistance measurement mechanism, which can be set by those skilled in the art themselves.

[0055] So far, the technical solution of the present application has been described in combination with the foregoing preferred embodiments. However, it is easy for those skilled in the art to understand that the protection scope of the present application is not limited to the above-mentioned preferred embodiments. Without departing from the technical principle of the present application, those skilled in the art can split and combine the technical solutions in the above-mentioned preferred embodiments, or make equivalent changes or substitutions to the relevant technical features. Any changes, equivalent substitutions, improvements, etc. made within the technical concept and / or technical principle of the present application will fall within the protection scope of the present application.

Claims

1. A method for preparing an attenuator, characterized in that, Including the following steps: Step 1: Use a vacuum coating machine to coat a carbon film on the area to be coated in the clamping rod to form a coated area, and the actual thickness value of any point in the coated area is not lower than the preset value; Step 2: Divide the coated area into multiple sub-areas along the axial direction of the clamping rod, measure the resistance of each sub-area, and calculate the actual thickness value of the carbon film in each sub-area based on the resistance of the sub-area, the size of the clamping rod, the length of the sub-area, and the resistivity of the carbon film; Step 3: Compare the actual thickness value of each sub-area with the preset value, and use laser ablation to remove the carbon film with excessive thickness; Control the thickness of the carbon film ablated and removed by controlling the laser ablation parameters, and the laser ablation parameters include laser power and ablation time; Before Step 3, establish a mathematical model of the ablation thickness and laser ablation parameters of the carbon film on the surface of the attenuator during laser ablation; The method for establishing the mathematical model is as follows: Take the laser power as a fixed value and the ablation time parameter as a variable, and obtain multiple sets of carbon film thickness values before and after ablation through experiments; obtain a mathematical model characterizing the corresponding relationship between ablation time and ablation thickness under unit laser power; take the ablation time parameter as a fixed value and the laser power as a variable, and obtain multiple sets of carbon film thickness values before and after ablation through experiments; obtain a mathematical model characterizing the corresponding relationship between laser power and ablation thickness per unit time; The actual thickness of the carbon film in the sub-area calculated in Step 2 is the average thickness, and use this average thickness to characterize the actual thickness of the carbon film in the sub-area; measure the resistance value of the carbon film in the test area of the attenuator, and obtain the thickness of the carbon film before and after ablation through the resistance value, the length of the test area, the size of the clamping rod, and the resistivity of the carbon film.

2. The method for preparing an attenuator according to claim 1, wherein Use a scanning electron microscope to measure the cross-sectional image of the attenuator to obtain the thickness of the carbon film before and after ablation.

3. The method for preparing an attenuator according to claim 1, characterized in that, In Step 1, coat multiple clamping rods simultaneously in the working chamber of the vacuum coating machine each time.

4. An attenuator preparation system for implementing the attenuator preparation method according to any one of claims 1-3, characterized in that, Including: A vacuum coating machine, used to accommodate the clamping rod and coat a carbon film on the area to be coated; A resistance measurement mechanism, used to obtain the resistance values of multiple sub-areas along the axial direction of the clamping rod; A laser ablation mechanism, used to ablate the carbon film with excessive thickness on the surface of the clamping rod; A controller, used to obtain the actual thickness of the carbon film based on the resistance value, the preset resistivity of the carbon film, and the clamping rod parameters, obtain the thickness to be ablated according to the difference between the actual thickness of the carbon film and the preset thickness, and control the ablation parameters of the laser ablation mechanism according to the thickness to be ablated.

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