Getter coating method and device for elliptical vacuum box used for synchrotron radiation source

Abstract

The present invention discloses a getter coating method and device for an elliptical vacuum box for a synchrotron radiation light source, wherein the method is to produce a cathode wire target with spiral wire segments and ceramic shielding segments alternately distributed on the surface, so that a coating area within a specific length range is formed in the vacuum box, and at the same time, the vacuum box is divided into a multi-segment structure, the coating process is divided into two stages of coating, the coating segments and shielding segments in the first coating stage and the second coating stage are swapped, and a complete coating process is formed after two stages of coating; the device comprises a frame, a solenoid, a lifting platform, an elliptical vacuum box, a cathode wire target and a first bellows, the vacuum box is vertically installed in the frame, the cathode wire target is arranged in the vacuum box, and the top of the cathode wire target is connected to the first bellows, the solenoid is arranged at the periphery of the vacuum box, and the solenoid is installed in the frame through the lifting platform. The present invention can achieve uniform coating in the entire area of ​​a large-length, small-diameter elliptical vacuum box.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum box coating of synchrotron radiation light sources, and in particular to a getter coating method and device for an elliptical vacuum box used for a synchrotron radiation light source. Background Art

[0002] With the rise of the fourth-generation synchrotron radiation source, its extremely low emissivity storage ring adopts a compact magnetic focusing structure design, and a large number of small-aperture magnets with high gradient focusing characteristics are used. However, the small-aperture magnets lead to a reduction in the size of the vacuum box, which seriously limits the flow conductance of the vacuum box and prevents the effective pumping speed of the vacuum pump from being fully utilized. In order to improve the pumping efficiency of the vacuum system and reduce the space occupied by the centralized vacuum pump, it is necessary to coat a layer of non-evaporable getter (NEG) film on the inner surface of the vacuum box to replace the traditional centralized vacuum pump. The application of NEG film can greatly simplify the structure of the vacuum box, especially after the NEG film is activated, its vacuum performance is excellent, and the photon desorption yield (PSD) and electron desorption yield (ESD) are small, which meets the requirements of beam physics for extremely high vacuum. Therefore, coating the inner wall of the vacuum box with a non-evaporable film has become a key technology for the fourth-generation synchrotron radiation source.

[0003] After the inner wall of the IAU (In Air Undulator) insert vacuum box of the synchrotron radiation source is coated with a getter, it can meet the dynamic vacuum requirements of the synchrotron radiation source storage ring, and then meet the requirements of the electron lifetime. The IAU insert is an important equipment of the fourth-generation synchrotron radiation source, used to produce high-quality synchrotron radiation light. At present, the IAU vacuum box is generally divided into coated IAU vacuum box and non-coated IAU vacuum box in the world. Generally, the average vacuum degree of the coated IAU vacuum box is an order of magnitude better than that of the non-coated IAU vacuum box. At the same time, due to the low PSD, ESD and other characteristics of the getter film, the coated IAU vacuum box is a good choice for the vacuum outer insert used in long straight sections.

[0004] However, since the IAU vacuum box is generally an elliptical structure (for example, the typical size of the IAU vacuum box in the synchrotron radiation light source project is 22×7.3mm 2 , length 5160mm), how to deposit NEG thin film on its inner wall is the key to the successful application of coating type IAU vacuum box.

[0005] The IAU vacuum box for synchrotron radiation light source coating (IAU vacuum box for short) has the smallest cross-sectional dimensions, especially the elliptical minor axis dimension of 7.3mm and a total length of more than 5m. The magnetron sputtering method with an external solenoid is the most widely used method for depositing NEG films on the inner wall of such slender vacuum boxes. For circular cross-sectional vacuum boxes with an inner diameter greater than 10mm, the coating difficulty is relatively small, and all major laboratories have mastered the film-forming process. However, for vacuum boxes with an inner diameter less than 10mm and a length greater than 5m, especially the IAU vacuum box with an elliptical cross-section, due to the small minor axis and long length of the cross-sectional area, the coating equipment and site requirements are high. Although the mobile solenoid coating method can avoid the problem of too large a device and difficult installation and operation, in actual experiments, it is still difficult to solve the problem of axial and circumferential uniformity of film thickness in the entire area of ​​the vacuum box. At present, through simulation analysis, it is found that due to the existence of the solenoid fringe field, at the end of the solenoid (such as Z<150mm), due to the existence of the magnetic field gradient and the intersection of the magnetic flux lines with the vacuum box (anode), the electrons (including electrons generated in the area and electrons entering from the outside) will quickly die, and will not collide enough with the inert gas (argon gas), and will not be fully ionized, resulting in insufficient discharge in the vacuum box in the end area of ​​the solenoid, and affecting the adjacent areas, causing unstable discharge, which can easily lead to poor thin film deposition effects, such as no film formation, unstable film formation area or poor film thickness uniformity. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a method for coating a getter in an elliptical vacuum box for a synchrotron radiation light source. The coating method is proposed for an IAU vacuum box with an elliptical cross-section (applicable to both rectangular vacuum boxes with a width ≤ 10 and circular vacuum boxes with a φ < 10), and can effectively improve the coating uniformity in the entire area of ​​the vacuum box.

[0007] Another object of the present invention is to provide an elliptical vacuum box getter coating device for a synchrotron radiation light source for implementing the above-mentioned coating method.

[0008] The technical solution of the present invention is: a method for coating a getter film of an elliptical vacuum box for a synchrotron radiation light source, comprising the following steps:

[0009] (1) Target production and installation: Ti wire, Zr wire and V wire are uniformly spirally wound on a tungsten steel rod. After winding, the tungsten steel rod is removed to form a spiral hollow section. After cleaning the spiral hollow section, several spiral hollow sections are strung on a straightened Ti wire to form a complete spiral wire section. After the spiral wire sections are strung, a ceramic tube of the same length is sleeved on the Ti wire at the adjacent position (the inner diameter of the ceramic tube is larger than the diameter of the Ti wire but smaller than the outer diameter of the spiral wire section) to form a ceramic shielding section. Then, the same length of spiral wire sections are strung on the Ti wire, and this process is repeated alternately to form a cathode wire target with spiral wire sections (titanium zirconium vanadium) and ceramic shielding sections arranged alternately.

[0010] The cathode wire target is installed in the vacuum box, the top end (Ti core) of the cathode wire target is connected to the first bellows, and the bottom end (Ti core) of the cathode wire target is connected to the weight mechanism;

[0011] The upper and lower ends of the vacuum box are shielding areas respectively, and capsule-shaped ceramics are arranged at both ends of the shielding areas, which are used to maintain the relative position between the cathode and the vacuum box, and there is a ceramic tube between the capsule-shaped ceramic and the spiral wire segment, the purpose is to prevent the entire surface of the capsule-shaped ceramic from being deposited with a thin film during the coating process, thereby causing a short circuit; the weight is placed in the solenoid, and a certain length of shielding ceramic is placed between it and the spiral wire segment, and the relative position of the spiral wire segment and the vacuum box in the axial direction can be adjusted by adjusting the length of the first bellows;

[0012] (2) The first coating stage: The cathode wire target is composed of several spiral wire segments and ceramic shielding segments of the same length from top to bottom. The spiral wire segments and the corresponding area of ​​the vacuum box (anode) maintain an electron path. Electrons are continuously generated on the surface of the cathode wire target and fly to the anode, colliding with Ar atoms to produce Ar ions. Ar ions bombard the target material to produce secondary electrons and sputtered atoms. This area can maintain continuous discharge under the action of the orthogonal electromagnetic field of E×B (where E is the electric field intensity and B is the magnetic induction intensity). The sputtered atoms fly to the anode to form a coating segment (i.e., the area corresponding to the inner wall of the vacuum box and the spiral wire segment on the cathode wire target). Each coating segment has the same length (the length is L), and multiple spaced coating segments are collectively referred to as the first stage coating area. In the area corresponding to the ceramic shielding segment on the cathode wire target, since the ceramic blocks electrons and ions and cannot maintain discharge, the length of each ceramic shielding segment (except for the two ends of the cathode) is the same and equal to the length of a single coating segment (i.e., the length is also L). Multiple spaced shielding segments are collectively referred to as the first stage shielding area;

[0013] There are multiple solenoid stations distributed from top to bottom on the periphery of the vacuum box, and each solenoid station should meet the following position conditions: 1. The edge field areas at the upper and lower ends of the solenoid must correspond to the two ceramic shielding segments on the cathode target; 2. The coating segment between the above two shielding segments is symmetrical about the center point of the solenoid; 3. The coating segment covered by each solenoid station does not overlap with the coating segment covered by other stations; 4. The coating process needs to cover each coating segment in the same solenoid station; the above multiple solenoid stations are collectively referred to as the first stage station group.

[0014] At the beginning of coating, the solenoid is first adjusted to a solenoid station, and after adjusting the air pressure and cathode potential, the coating of the inner wall of the vacuum box corresponding to each spiral wire segment in the solenoid station is completed. Then, the solenoid is hoisted by the lifting platform and adjusted to the next solenoid station for coating. After the coating is completed one by one in all the solenoid stations, the first coating stage is completed, and at this time, half of the inner wall of the vacuum box has been coated;

[0015] (3) The second coating stage: first, adjust the length of the first bellows (i.e., the compression length of the first bellows is L) to make the cathode target material axially displaced relative to the vacuum box (the displacement length is L), so that each spiral wire segment in the first-stage coating area is opposite to the first-stage shielding area, forming the second-stage coating area; and each ceramic shielding segment in the first-stage shielding area is opposite to the first-stage coating area, forming the second-stage shielding area; correspondingly, each station of the first-stage station group descends (the descending height is L) to form the second-stage station group; then, each solenoid station of the second-stage station group is plated to complete the entire coating process.

[0016] In the step (1), when the Ti wire, Zr wire and V wire are uniformly spirally wound on the tungsten steel rod, the diameters of the Ti wire, Zr wire and V wire are 0.5 mm respectively, and the diameter of the tungsten steel rod is 1 mm; when multiple spiral wire segments are connected in series on a straightened Ti wire (also called "center Ti wire"), the diameter of the Ti wire used is 1 mm. The straightness of the tungsten steel is required to be better than 0.01 mm, and the straightness of the center Ti wire is also required to be better than 0.01 mm.

[0017] In the step (1), when the hollow segment of the spiral wire is cleaned, the oil stain is first removed by chemical cleaning, and then the oxide layer on the surface of the spiral wire segment is removed by plasma discharge. Since the target material will inevitably cause certain target material contamination during the preparation process, and since the target material itself has a certain oxide layer on the surface, in order to ensure the cleanliness and purity of the target surface, the spiral wire segment is subjected to the above cleaning work after winding, which can quickly clean the oxide skin on the surface of the spiral wire segment and release the internal stress of the spiral wire, so as to ensure that the surface of the target material after forming is all fresh pure metal.

[0018] In the step (1), after the cathode wire target is formed, a weight mechanism is installed at the bottom of the cathode wire target.

[0019] The vacuum box is baked and evacuated to a vacuum degree of <5×10 -7 Pa, to ensure that there is no impurity gas in the vacuum box that interferes with the coating;

[0020] In the steps (2) and (3), when coating is performed at each solenoid station, the vacuum box is grounded through a ground wire, and at the same time, the cathode wire target is powered to generate a magnetic field required for plasma discharge. After 99.999% high-purity argon gas is introduced as a discharge gas, a voltage of -300 V is loaded on the cathode wire target to cause glow discharge in the vacuum box, thereby producing a large amount of electrons and Ar+. Then, under the action of the sheath voltage, the Ar+ rushes toward the cathode wire target, knocking out the metal atoms on the surface of the cathode wire target, and the metal atoms fly toward the inner wall of the vacuum box, thereby forming a target coating layer.

[0021] In the steps (2) and (3), when coating is performed at each solenoid station, the coating discharge parameters are as follows: the discharge pressure is 10Pa; the discharge voltage is -300V; the solenoid current is 24A, the center field is 570Gs; the discharge current is 40mA; and the coating time for each solenoid station is 2h.

[0022] The present invention provides an elliptical vacuum box getter coating device for a synchrotron radiation light source for implementing the above-mentioned coating method, characterized in that it includes a frame, a solenoid, a lifting platform, an elliptical vacuum box, a cathode filament target and a first bellows, the vacuum box is vertically installed in the frame, the cathode filament target is arranged in the vacuum box, and the top of the cathode filament target is connected to the first bellows, the solenoid is arranged on the periphery of the vacuum box, and the solenoid is installed in the frame through the lifting platform. In the coating device structure, the elliptical vacuum box is the vacuum box whose inner wall is to be coated. The vacuum box is fixedly installed in the frame. The cathode wire target inside the vacuum box can adjust the relative position of its spiral wire segment and ceramic shielding segment with the inner wall of the vacuum box through the first bellows, so as to achieve the position adjustment between the coating segment and the shielding segment. The height of the solenoid corresponds to a solenoid station (also called coating station) of the vacuum box. The solenoid can be driven to move up and down in the frame through the lifting platform, so as to adjust the solenoid to correspond to different solenoid stations on the vacuum box, and then the solenoid cooperates with the cathode wire target to complete the coating work of the inner wall of the vacuum box in each solenoid station. Among them, the frame, the solenoid and the lifting platform constitute a movable support mechanism, and its specific structure can adopt the same structure as the magnetic field movable coating device disclosed in the invention application with the publication number of CN113174581A.

[0023] The cathode wire target comprises a core, alternately distributed and equal-length spiral wire segments and a ceramic shielding segment, wherein the core is a central Ti wire, and the spiral wire segment comprises a plurality of spiral wire hollow segments connected in series on the core, wherein each spiral wire hollow segment is formed by alternately and evenly winding Ti wire, Zr wire and V wire respectively; and the ceramic shielding segment is a ceramic jacket. That is, the surface of the cathode wire target forms alternately connected spiral wire segments (also called target material segments) and ceramic shielding segments.

[0024] A first connecting transition section is provided between the cathode wire target and the first bellows, and the cathode wire target is connected to the first bellows through the first connecting transition section. A cathode assembly is also provided on the top of the first bellows, and the top of the spiral wire target is connected to the cathode assembly after passing through the first connecting transition section and the first bellows; a connecting flange is provided on the top of the vacuum box, and the vacuum box is fixedly connected to the bottom of the first connecting transition section through the connecting flange. Among them, the first bellows, the first connecting transition section and the vacuum box are coaxially arranged. When the first bellows drives the cathode wire target to move, the cathode assembly on the top of the first bellows follows the movement, but the first connecting transition section and the vacuum box remain stationary. During the coating process at each station, electrons are generated by the discharge of the cathode assembly, and the electrons collide with the argon gas to generate Ar+ in the vacuum box. The cathode wire target is hit by Ar+, and the generated metal atoms fly to the inner wall of the vacuum box and are adsorbed by the inner wall of the vacuum box to form the required uniform coating layer.

[0025] A weight mechanism is provided at the bottom of the cathode wire target, and the weight mechanism includes a second bellows and a second connecting transition section connected to each other, a weight is provided in the second connecting transition section, and a target wire fixing head is provided on the top of the weight, the lower end of the cathode wire target is fixedly mounted on the target wire fixing head, and an end ceramic plate is provided at the lower end of the weight, and the end ceramic plate and the weight are locked and fixed by a ceramic screw. Among them, since the cathode wire target is relatively long and has a relatively small diameter, the weight is connected to the lower end of the cathode wire target through the target wire fixing head, which can ensure the verticality of the center Ti wire, and then the spiral wire segment connected in series with the center Ti wire also has corresponding straightness, thereby improving and enhancing the verticality of the entire cathode wire target, so as to further ensure the uniformity of the coating on the inner wall of the vacuum box. The second bellows can play an auxiliary role when the first bellows adjusts the height of the cathode wire target.

[0026] When the above-mentioned method and device for coating getters in an elliptical vacuum box for a synchrotron radiation light source are used, the principle is as follows: by manufacturing a cathode wire target with spiral wire segments and ceramic shielding segments alternately distributed on the surface, a coating area within a specific length range is formed in the vacuum box, and at the same time, by dividing the vacuum box into a multi-segment structure, the coating process is divided into two stages of coating, and the coating segments and shielding segments in the first coating stage and the second coating stage are swapped, and a complete coating process is formed after two stages of coating; this is because it was found during the simulation analysis process that for the inner wall of the elliptical vacuum box, due to the existence of the fringe field of the solenoid on the outer periphery of the vacuum box, the magnetic field is insufficient to constrain the electrons at the corresponding ends of the solenoid, and the electrons die prematurely. , insufficient collision with the inert gas (argon) and failure to produce sufficient ionization. If the traditional coating method is used, only the central area of ​​the part corresponding to the solenoid in the vacuum box can form a uniform film layer, while the parts corresponding to the two ends of the solenoid cannot form a uniform target film layer; therefore, the coating method and device use alternating coating sections and shielding sections, the length of each solenoid corresponds to a solenoid station, and each solenoid station corresponds to a vacuum box section formed by several coating sections and shielding sections, and the coating process is divided into two stages. In the two coating stages, the coating section and the shielding section are swapped by adjusting the height of the cathode wire target, so that the above-mentioned technical problems can be better overcome and uniform coating of the inner wall of the vacuum box can be achieved.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] In the getter coating method and device for an elliptical vacuum box used in a synchrotron radiation light source, for coating an IAU vacuum box with an elliptical cross-section, a cathode wire target having alternating spiral wire segments and ceramic shielding segments on the surface is manufactured, and the coating segment and the shielding segment are swapped by adjusting the height of the cathode wire target in the first and second coating stages, thereby achieving coating uniformity in the entire area of ​​the elliptical vacuum box with a large length and a small diameter.

[0029] In the method and device for coating the getter of the elliptical vacuum box used in the synchrotron radiation light source, the cathode wire target has the following advantages: 1. Good straightness. After installation, the target spacing is consistent in the entire vacuum box area to be coated; 2. Since the cathode wire target is used in a small-aperture vacuum box with an elliptical cross-section, the target spacing is small, and a large magnetic field strength and a high current density are required during discharge (so that the plasma can diffuse in the entire target area). At the same time, overheating of the cathode should be avoided, which is easy to break the cathode. The cathode wire target is composed of a middle support part (i.e., a central Ti wire) and a surface target part (i.e., a titanium wire, a zirconium wire, and a vanadium wire), and can withstand a higher temperature than a traditional wire-wound target; 3. Generally speaking, the composition ratio distribution of the target material determines the composition of the thin film in the area to be coated. The cathode wire target adopts a spiral dense distribution method, and its composition uniformity is better than that of a traditional wire-wound target; 4. The cathode wire target has a larger surface area than traditional alloy targets and traditional wire-wound targets, and can generate more secondary electrons during sputtering, thereby making it easier to maintain magnetron sputtering discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the principle of the cathode wire target in this coating device.

[0031] Figure 2 Schematic diagram of the cathode wire target structure.

[0032] Figure 3 This is a radial cross-sectional view of the cathode wire target.

[0033] Figure 4 This is a schematic diagram of the structure after the cathode wire target is placed in the vacuum box.

[0034] Figure 5 for Figure 4 Schematic diagram of the principle of a single solenoid station corresponding to the solenoid in direction A.

[0035] Figure 6 It is a structural diagram of the heavy hammer mechanism.

[0036] Figure 7 This is an electron microscope image of the surface morphology of the film layer on the inner wall of the vacuum box after coating.

[0037] Figure 8 This is an electron microscope image of the cross-sectional morphology of the film layer on the inner wall of the vacuum box after coating.

[0038] In the above figures, the components indicated by the reference numerals are as follows:

[0039] 1 is a solenoid, 2 is a vacuum box, 3 is a cathode wire target, 3-1 is a spiral wire segment, 3-2 is a ceramic shielding segment, 4 is a first bellows, 5 is a surface Ti wire, 6 is a Zr wire, 7 is a V wire, 8 is a center Ti wire, 9 is a first connecting transition segment, 10 is a cathode assembly, 11 is a connecting flange, 12 is a heavy hammer mechanism, 13 is a second bellows, 14 is a second connecting transition segment, 15 is a heavy hammer, 16 is a target wire fixing head, 17 is an end ceramic plate, and 18 is a ceramic screw. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0041] Example

[0042] This embodiment provides a getter coating method and device for an elliptical vacuum box used for a synchrotron radiation light source.

[0043] The method for coating a getter film of an elliptical vacuum box for a synchrotron radiation source comprises the following steps:

[0044] (1) Target production and installation: Figure 2 As shown, the surface Ti wire 5, Zr wire 6 and V wire 7 are uniformly spirally wound on a tungsten steel rod. After the winding is completed, the tungsten steel rod is removed to form a spiral wire hollow segment. After the spiral wire hollow segment is cleaned, multiple spiral wire hollow segments are connected in series to a straightened Ti wire (i.e., the central Ti wire 8) to form a complete spiral wire segment 3-1; after the spiral wire segments are strung together, a ceramic tube of the same length is sleeved on the Ti wire at the adjacent position (the inner diameter of the ceramic tube is larger than the diameter of the Ti wire but smaller than the outer diameter of the spiral wire segment) to form a ceramic shielding segment 3-2; then, the spiral wire segments of the same length are strung together on the Ti wire, and this process is repeated alternately to form a cathode wire target in which the spiral wire segments (titanium zirconium vanadium) and the ceramic shielding segments are alternately arranged;

[0045] The cathode wire target is installed in the vacuum box, the top end (Ti core) of the cathode wire target is connected to the first bellows, and the bottom end (Ti core) of the cathode wire target is connected to the weight mechanism;

[0046] The upper and lower ends of the vacuum box are shielding areas respectively, and capsule-shaped ceramics are arranged at both ends of the shielding areas, which are used to maintain the relative position between the cathode and the vacuum box, and there is a ceramic tube between the capsule-shaped ceramic and the spiral wire segment, the purpose is to prevent the entire surface of the capsule-shaped ceramic from being deposited with a thin film during the coating process, thereby causing a short circuit; the weight is placed in the solenoid, and a certain length of shielding ceramic is placed between it and the spiral wire segment, and the relative position of the spiral wire segment and the vacuum box in the axial direction can be adjusted by adjusting the length of the first bellows;

[0047] When the Ti wire, Zr wire and V wire are uniformly spirally wound on the tungsten steel rod, the diameters of the Ti wire, Zr wire and V wire are 0.5mm respectively, and the diameter of the tungsten steel rod is 1mm; when multiple spiral wire segments are connected in series on a straightened Ti wire (also called "center Ti wire"), the diameter of the Ti wire used is 1mm. Among them, the straightness of the tungsten steel is required to be better than 0.01mm, and the straightness of the center Ti wire is also required to be better than 0.01mm; after the cathode wire target is formed, a heavy hammer mechanism is also installed at the bottom of the cathode wire target;

[0048] When cleaning the hollow section of the spiral wire, first remove the oil stains by chemical cleaning, and then remove the oxide layer on the surface of the spiral wire section by plasma discharge;

[0049] Before coating, the vacuum box is baked and evacuated to a vacuum degree of <5×10 -7 Pa, to ensure that there is no impurity gas in the vacuum box that interferes with the coating;

[0050] (2) The first coating stage: The cathode wire target is composed of several spiral wire segments and ceramic shielding segments of the same length from top to bottom. The spiral wire segments and the corresponding area of ​​the vacuum box (anode) maintain an electron path. Electrons are continuously generated on the surface of the cathode wire target and fly to the anode, colliding with Ar atoms to produce Ar ions. Ar ions bombard the target material to produce secondary electrons and sputtered atoms. This area can maintain continuous discharge under the action of the orthogonal electromagnetic field of E×B (where E is the electric field intensity and B is the magnetic induction intensity). The sputtered atoms fly to the anode to form a coating segment (i.e., the area corresponding to the inner wall of the vacuum box and the spiral wire segment on the cathode wire target). Each coating segment has the same length (the length is L). Multiple spaced spiral wire segments (also called coating segments) are collectively referred to as the first stage coating area. In the area corresponding to the ceramic shielding segment on the cathode wire target, since the ceramic blocks electrons and ions and cannot maintain discharge, the length of each ceramic shielding segment (except for the two ends of the cathode) is the same and equal to the length of a single coating segment (i.e., the length is also L). Multiple spaced shielding segments are collectively referred to as the first stage shielding area;

[0051] There are multiple solenoid stations distributed from top to bottom around the vacuum box, and each solenoid station should meet the following position conditions: 1. The edge field areas at the upper and lower ends of the solenoid must correspond to the two ceramic shielding segments on the cathode target; 2. The coating segment between the above two shielding segments is symmetrical about the center point of the solenoid; 3. The coating segment covered by each solenoid station does not overlap with the coating segment covered by other stations; 4. The coating process needs to cover each coating segment in the same solenoid station; the above multiple solenoid stations are collectively referred to as the first stage station group;

[0052] At the beginning of coating, the solenoid is first adjusted to a solenoid station, and after adjusting the air pressure and cathode potential, the coating of the inner wall of the vacuum box corresponding to each spiral wire segment in the solenoid station is completed. Then, the solenoid is hoisted by the lifting platform and adjusted to the next solenoid station for coating. After the coating is completed one by one in all the solenoid stations, the first coating stage is completed, and at this time, half of the inner wall of the vacuum box has been coated;

[0053] (3) Second coating stage: First, adjust the length of the first bellows (i.e., the compression length of the first bellows is L) to make the cathode target material axially displaced relative to the vacuum box (the displacement length is L), so that each spiral wire segment in the first-stage coating area is opposite to the first-stage shielding area, forming the second-stage coating area; and each ceramic shielding segment in the first-stage shielding area is opposite to the first-stage coating area, forming the second-stage shielding area; correspondingly, each station of the first-stage station group descends (the descending height is L) to form the second-stage station group; then, coat each solenoid station of the second-stage station group to complete the entire coating process;

[0054] In the above steps (2) and (3), when coating is performed at each solenoid station, the vacuum box is grounded through the ground wire, and the cathode wire target is powered to generate the magnetic field required for plasma discharge. After the discharge gas 99.999% high-purity argon is introduced, a voltage of -300V is loaded on the cathode wire target, so that the vacuum box glow discharges and produces a large number of electrons and Ar+. Then, under the action of the sheath voltage, the Ar+ rushes to the cathode wire target, knocking out the metal atoms on the surface of the cathode wire target, and the metal atoms fly to the inner wall of the vacuum box, thereby forming the target coating layer. When coating is performed at each solenoid station, the coating discharge parameters are as follows: the discharge pressure is 10Pa; the discharge voltage is -300V; the solenoid current is 24A, the central field is 570Gs; the discharge current is 40mA; and the coating time of each solenoid station is 2h.

[0055] The embodiment of the present invention is used to implement the above-mentioned coating method of the oval vacuum box getter coating device for the synchrotron radiation light source, such as Figure 5 As shown, it includes a frame (not shown in the figure), a solenoid 1, a lifting platform (not shown in the figure), an elliptical vacuum box 2, a cathode wire target 3 (such as Figure 1As shown) and the first bellows 4, the vacuum box is vertically installed in the frame, the cathode wire target is arranged in the vacuum box, and the top of the cathode wire target is connected to the first bellows, the solenoid is arranged on the periphery of the vacuum box, and the solenoid is installed in the frame through a lifting platform. In the coating device structure, the elliptical vacuum box is a vacuum box whose inner wall is to be coated, and the vacuum box is fixedly installed in the frame. The cathode wire target inside it can adjust the relative position of its spiral wire segment and ceramic shielding segment with the inner wall of the vacuum box through the first bellows, so as to achieve the position adjustment between the coating segment and the shielding segment. The height of the solenoid corresponds to a solenoid station of the vacuum box. The lifting platform can drive the solenoid to move up and down in the frame, so as to adjust the solenoid to correspond to different solenoid stations on the vacuum box, and then the solenoid cooperates with the cathode wire target to complete the coating work of the inner wall of the vacuum box in each solenoid station. Among them, the frame, solenoid and lifting platform constitute a movable supporting mechanism, and its specific structure can adopt the same structure as the magnetic field movable coating device disclosed in the invention application with publication number CN113174581A.

[0056] like Figure 1 As shown, the cathode wire target 3 includes a core, alternately distributed and equal-length spiral wire segments and a ceramic shielding segment. The core is a central Ti wire. The spiral wire segment includes multiple spiral wire hollow segments connected in series on the core. Each spiral wire hollow segment is formed by alternately and evenly winding Ti wire, Zr wire and V wire respectively; the ceramic shielding segment is set on the core with a ceramic tube sleeve. That is, the surface of the spiral wire target forms alternately connected spiral wire segments 3-1 (also called target material segments) and ceramic shielding segments 3-2.

[0057] A first connecting transition section 9 is provided between the cathode wire target and the first bellows, and the cathode wire target is connected to the first bellows through the first connecting transition section. A cathode assembly 10 is also provided on the top of the first bellows, and the top of the cathode wire target is connected to the cathode assembly after passing through the first connecting transition section and the first bellows; a connecting flange 11 is provided on the top of the vacuum box, and the vacuum box is fixedly connected to the bottom of the first connecting transition section through the connecting flange. Among them, the first bellows, the first connecting transition section and the vacuum box are coaxially arranged. When the first bellows drives the cathode wire target to move, the cathode assembly on the top of the first bellows follows the movement, but the first connecting transition section and the vacuum box remain stationary. In the coating process of each station, electrons are generated by the discharge of the cathode assembly, and the electrons collide with the argon gas to generate Ar+ in the vacuum box. The cathode wire target is hit by Ar+, and the generated metal atoms are scattered to the inner wall of the vacuum box, and are adsorbed by the inner wall of the vacuum box to form the required uniform coating layer.

[0058] A weight mechanism 12 is provided at the bottom of the cathode wire target. Figure 6As shown, the weight mechanism includes a second bellows 13 and a second connecting transition section 14 connected to each other, a weight 15 is arranged in the second connecting transition section, and a target wire fixing head 16 is arranged on the top of the weight, the lower end of the cathode wire target is fixedly mounted on the target wire fixing head, an end ceramic plate 17 is arranged at the lower end of the weight, and the end ceramic plate and the weight are locked and fixed by a ceramic screw 18 (the arrangement of the end ceramic plate and the ceramic screw can shield the weight and the cathode wire target above it). Among them, since the cathode wire target is relatively long and has a relatively small diameter, the weight is connected to the lower end of the cathode wire target through the target wire fixing head, which can ensure the verticality of the center Ti wire, and then the spiral wire segment connected in series with the center Ti wire also has corresponding straightness, thereby improving and enhancing the verticality of the entire cathode wire target, so as to further ensure the uniformity of the coating on the inner wall of the vacuum box. The second bellows can play an auxiliary role when the first bellows adjusts the height of the cathode wire target.

[0059] When the above-mentioned method and device for coating getters in an elliptical vacuum box for a synchrotron radiation source are used, the principle is as follows: by making a cathode wire target with alternating spiral wire segments and ceramic shielding segments, a coating area within a specific length range is formed in the vacuum box, and at the same time, by dividing the vacuum box into a multi-segment structure, the coating process is divided into two stages of coating, and the coating segments and shielding segments in the first coating stage and the second coating stage are swapped, and a complete coating process is formed after two stages of coating; this is because it was found in the simulation analysis process that for the inner wall of the elliptical vacuum box, due to the existence of the fringe field of the solenoid on the outer periphery of the vacuum box, the magnetic field is insufficient to constrain the electrons at the corresponding ends of the solenoid, and the electrons die prematurely, which is related to the fact that the inner wall of the elliptical vacuum box is shaped like a vacuum box, and ... The inert gas (argon) does not collide enough and fails to produce sufficient ionization. If the traditional coating method is used, only the central area of ​​the part corresponding to the solenoid in the vacuum box can form a uniform film layer, while the parts corresponding to the two ends of the solenoid cannot form a uniform target film layer; therefore, the present coating method and device use alternating coating sections and shielding sections, the length of each solenoid corresponds to a solenoid station, and each solenoid station corresponds to a vacuum box section formed by several coating sections and shielding sections, and the coating process is divided into two stages. In the two coating stages, the coating section and the shielding section are swapped by adjusting the height of the cathode wire target, so that the above-mentioned technical problems can be better overcome and uniform coating of the inner wall of the vacuum box can be achieved.

[0060] The film layer on the inner wall of the elliptical vacuum box obtained after coating by the above-mentioned coating device and method was detected, and samples were taken along the two ends of the long diameter, the two ends of the short diameter, and the arc surface between the long diameter and the short diameter of the elliptical vacuum box, and the film thickness of each sample was detected. It was found that the film thickness at the two ends of the short diameter was the largest, followed by the film thickness of the arc surface between the long diameter and the short diameter, and the film thickness at the two ends of the long diameter was the thinnest. The difference was caused by the distribution of the target spacing, but the surface morphology of each sample (such as Figure 7) and cross-sectional morphology (as shown Figure 8 No obvious film defects were found in the samples (as shown), and the coating uniformity was high.

[0061] As described above, the present invention can be better implemented. The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention; that is, all equivalent changes and modifications made according to the content of the present invention are covered by the scope of protection required by the claims of the present invention.

Claims

1. A method for coating a getter film of an elliptical vacuum box for a synchrotron radiation source, characterized in that: The following steps are involved: (1) Target material preparation and installation: Ti wire, Zr wire and V wire are uniformly spirally wound on a tungsten steel rod. After the winding is completed, the tungsten steel rod is removed to form a spiral wire hollow segment. After the spiral wire hollow segment is cleaned, several spiral wire hollow segments are connected in series to a straightened Ti wire to form a complete spiral wire segment. After the spiral wire segments are connected in series, a ceramic tube of the same length is set on the Ti wire at the adjacent position to form a ceramic shielding segment. Then, the spiral wire segments of the same length are connected in series on the Ti wire, and this process is repeated alternately to form a cathode wire target with spiral wire segments and ceramic shielding segments arranged alternately. The cathode wire target is installed in the vacuum box, the top end of the cathode wire target is connected to the first bellows, and the bottom end of the cathode wire target is connected to the weight mechanism; (2) The first coating stage: The cathode wire target is composed of a number of spiral wire segments and ceramic shielding segments of the same length from top to bottom, in which the electron path is maintained between the spiral wire segments and the corresponding areas of the vacuum box. The multiple spaced spiral wire segments are collectively referred to as the first-stage coating area; in the area corresponding to the ceramic shielding segment on the cathode wire target, the length of each ceramic shielding segment is the same and equal to the length of a single spiral wire segment. The multiple spaced ceramic shielding segments are collectively referred to as the first-stage shielding area; There are multiple solenoid stations distributed from top to bottom on the periphery of the vacuum box, and the multiple solenoid stations are collectively referred to as the first-stage station group; each solenoid station should meet the following position conditions:

1. The edge field areas at the upper and lower ends of the solenoid must correspond to the two ceramic shielding segments on the cathode target; 2. The coating segment between the two shielding segments is symmetrical about the center point of the solenoid; 3. The coating segment covered by each solenoid station does not overlap with the coating segment covered by other stations; 4. The coating process needs to cover each coating segment in the same solenoid station; At the beginning of coating, the solenoid is first adjusted to a solenoid station, and after adjusting the air pressure and cathode potential, the coating of the inner wall of the vacuum box corresponding to each spiral wire segment in the solenoid station is completed. Then, the solenoid is hoisted by the lifting platform and adjusted to the next solenoid station for coating. After the coating is completed one by one in all the solenoid stations, the first coating stage is completed, and at this time, half of the inner wall of the vacuum box has been coated; (3) The second coating stage: first, adjust the length of the first bellows to make the cathode target material axially displaced relative to the vacuum box, so that each spiral wire segment in the first-stage coating area is opposite to the first-stage shielding area, forming the second-stage coating area, and each ceramic shielding segment in the first-stage shielding area is opposite to the first-stage coating area, forming the second-stage shielding area; correspondingly, each solenoid station of the first-stage station group descends to form a second-stage station group; then, each solenoid station of the second-stage station group is coated to complete the entire coating process.

2. The getter coating method for an elliptical vacuum box for a synchrotron radiation source according to claim 1, characterized in that: In step (1), when Ti wire, Zr wire and V wire are uniformly spirally wound on a tungsten steel rod, the diameters of the Ti wire, Zr wire and V wire are 0.5 mm respectively, and the diameter of the tungsten steel rod is 1 mm; when multiple spiral wire segments are connected in series on a straightened Ti wire, the diameter of the Ti wire used is 1 mm.

3. The getter coating method for an elliptical vacuum box for a synchrotron radiation source according to claim 1, characterized in that: In step (1), when the hollow segment of the spiral wire is cleaned, the oil stains are first removed by chemical cleaning, and then the oxide layer on the surface of the spiral wire segment is removed by plasma discharge.

4. The getter coating method for an elliptical vacuum box for a synchrotron radiation source according to claim 1, characterized in that: In step (1), after the cathode wire target is formed, a weight mechanism is installed at the bottom of the cathode wire target.

5. The getter coating method for an elliptical vacuum box for a synchrotron radiation source according to claim 1, characterized in that: The vacuum box is baked and evacuated to a vacuum degree of <5×10 -7 Pa; In step (2) and step (3), when coating is performed at each solenoid station, the vacuum box is grounded through the ground wire, and at the same time, the cathode wire target is powered to generate the magnetic field required for plasma discharge. After the discharge gas 99.999% high-purity argon gas is introduced, a voltage of -300V is loaded on the cathode wire target to cause glow discharge in the vacuum box, producing a large number of electrons and Ar+. Then, under the action of the sheath voltage, the Ar+ rushes toward the cathode wire target, knocking out the metal atoms on the surface of the cathode wire target, and the metal atoms fly to the inner wall of the vacuum box, thereby forming a target coating layer.

6. The getter coating method for an elliptical vacuum box for a synchrotron radiation source according to claim 1, characterized in that: In step (2) and step (3), when coating is performed at each solenoid station, the coating discharge parameters are as follows: the discharge pressure is 10Pa; the discharge voltage is -300V; the solenoid current is 24A, the center field is 570Gs; the discharge current is 40mA; and the coating time for each solenoid station is 2h.

7. A getter coating device for an elliptical vacuum box for a synchrotron radiation source, characterized in that: It includes a frame, a solenoid, a lifting platform, an elliptical vacuum box, a cathode wire target and a first bellows, wherein the vacuum box is vertically installed in the frame, the cathode wire target is arranged in the vacuum box, and the top of the cathode wire target is connected to the first bellows, the solenoid is arranged on the periphery of the vacuum box, and the solenoid is installed in the frame through the lifting platform; The cathode wire target comprises a core, spiral wire segments that are alternately distributed and of equal length, and a ceramic shielding segment. The core is a central Ti wire. The spiral wire segment comprises a plurality of spiral wire hollow segments that are serially connected to the core. Each spiral wire hollow segment is formed by alternately and evenly winding Ti wire, Zr wire and V wire. The ceramic shielding segment is arranged on the core by a ceramic tube sleeve. There are multiple solenoid stations distributed from top to bottom on the periphery of the vacuum box, and the multiple solenoid stations are collectively referred to as the first-stage station group; each solenoid station should meet the following position conditions:

1. The edge field areas at the upper and lower ends of the solenoid must correspond to the two ceramic shielding segments on the cathode target; 2. The coating segment between the two shielding segments is symmetrical about the center point of the solenoid; 3. The coating segment covered by each solenoid station does not overlap with the coating segments covered by other stations; 4. The coating process needs to cover each coating segment in the same solenoid station.

8. The getter coating device for an elliptical vacuum box for a synchrotron radiation source according to claim 7, characterized in that: A first connecting transition section is provided between the cathode wire target and the first bellows, and the cathode wire target is connected to the first bellows through the first connecting transition section. A cathode assembly is also provided on the top of the first bellows, and the top of the cathode wire target is connected to the cathode assembly after passing through the first connecting transition section and the first bellows; a connecting flange is provided on the top of the vacuum box, and the vacuum box is fixedly connected to the bottom of the first connecting transition section through the connecting flange.

9. The getter coating device for an elliptical vacuum box for a synchrotron radiation source according to claim 7, characterized in that: A weight mechanism is provided at the bottom of the cathode wire target, and the weight mechanism includes a second corrugated tube and a second connecting transition section connected to each other. A weight is provided in the second connecting transition section, and a target wire fixing head is provided on the top of the weight. The lower end of the cathode wire target is fixedly mounted on the target wire fixing head, and an end ceramic plate is provided at the lower end of the weight. The end ceramic plate and the weight are locked and fixed by ceramic screws.

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