A sleeve for assisting a quartz crystal microbalance in the corrosion study of first wall materials

Abstract

The present invention discloses a sleeve for assisting a quartz crystal microbalance in the study of first wall material corrosion, which includes a metal cylinder with different inner diameters, an insulating base, and a high-voltage power supply. After the metal cylinder with different inner diameters is embedded in the insulating base, they are installed together on the surface of the probe, and a positive bias voltage is maintained on the metal cylinder with different inner diameters by using the high-voltage power supply. The sleeve can form a flared structure in front of the quartz crystal, so that the projection of the circular coating area on the surface of the quartz crystal on the outermost closed magnetic surface of the plasma becomes a regular near-circle, and the flux of neutral particles incident on the circular coating area of the quartz crystal is reduced. At the same time, the positive bias voltage on the metal cylinder with different inner diameters can effectively prevent the incidence of impurity ions. The beneficial effects of the present invention include simplifying and accurately calculating the average solid angle of the circular coating area of the quartz crystal with respect to its projection area on the outermost closed magnetic surface of the plasma, extending the service life of the quartz crystal microbalance, and eliminating the interference of impurity deposition.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature plasma diagnostics, and particularly relates to a sleeve for assisting a quartz crystal microbalance in the study of the corrosion of first wall materials. Background Art

[0002] In recent years, the research on the corrosion of plasma-facing materials (PFMs) by neutral particles in the magnetic shadow region of a tokamak device has become a hot topic. The reasons are as follows: in the process of developing towards a future commercial fusion reactor, on the one hand, with the increase of the fusion power, the corrosion rate of PFMs by neutral particles will increase significantly; on the other hand, tritium and impurity particles are prone to co-deposit in the so-called magnetic shadow region where there is no direct plasma contact, which greatly affects the tritium retention rate of the whole device and seriously threatens the safe operation of the device. Neutral particles can affect the tritium retention rate in the device by dominating the corrosion deposition process in the magnetic shadow region.

[0003] EAST has taken the lead in carrying out relevant research on the generation of neutral particles and the corrosion mechanism of PFMs in the world by developing a Low Energy Neutral Particle Analyzer (LENPA) and a Quartz Crystal Microbalance (QMB) system. Among them, the low energy neutral particle analyzer can measure the energy spectrum of neutral particles in the magnetic shadow region, including the neutral particle flux and energy, providing necessary data for the theoretical calculation of the corrosion rate of PFMs by neutral particles, while the QMB can directly measure the mass change of PFMs in the magnetic shadow region by coating its quartz crystal surface to reflect its corrosion deposition process.

[0004] Based on the neutral particle energy spectrum, the theoretical corrosion rate S of PFMs on the quartz crystal surface of the QMB is calculated by the following formula:

[0005]

[0006] where A s and A p are respectively the coating area of PFMs on the quartz crystal and the projected area on the plasma surface. This projected area is also the approximate coating area corresponding to the neutral particle emission surface. $\Omega$ is the average solid angle of the coating area with respect to the projection area, $Y(E)$ is the sputtering yield related to the incident particle energy, species, and target material type, and $d\Gamma(E) / dEd\Omega$ is the neutral particle emission energy spectrum on the plasma surface. Through this formula, the neutral particle energy spectrum measured by LENPA can be converted into the theoretical corrosion rate of neutral particles on the PFMs of the QMB, and compared with the experimental corrosion rate actually measured by the QMB, closely integrating numerical calculation with experimental measurement. The coating area is generally chosen to be circular, so that the projection area is also nearly circular to simplify the calculation of the average solid angle. for the calculation.

[0007] However, in the implementation process, there are several problems to be solved. First, in order to save space in the tokamak experimental reactor, the observation window generally integrates different diagnostic systems. Many diagnostics require pipes to be placed in the inner vacuum chamber, which will have an adverse impact on the measurement of the QMB, resulting in an irregular shape of the projection area of the circular coating area on the quartz crystal of the QMB on the plasma surface through the pipes of adjacent diagnostic systems, bringing great difficulties and errors to the calculation of the average solid angle. Secondly, it is found that the QMB is damaged under the conditions of long-pulse high-parameter plasma discharge. This is mainly because the influence of temperature on the quartz crystal is only reversible within a certain range of conditions. When high-energy and high-flux neutral particles continuously impinge on the quartz crystal, even under the working conditions of the water-cooling system, the temperature will continue to rise, ultimately causing the quartz crystal to fail. Finally, after the entire round of experiments, the quartz crystal was taken out, and the surface material was characterized by techniques such as scanning electron microscopy. The presence of deposited elements such as tungsten was found, indicating that there is no lack of impurity deposition even in the magnetic shadow area far from the limiter, and the deposition of impurities will bring great errors to the calculation of the theoretical corrosion rate. Therefore, there is an urgent need for an auxiliary structure that can solve the above problems to improve the application of the QMB in the tokamak device. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a sleeve for an auxiliary quartz crystal microbalance used in the corrosion research of the first wall material. It is a simple and economical QMB auxiliary structure, which solves the problems that it is difficult to calculate the average solid angle between the circular coating area on the QMB quartz crystal and the corresponding neutral particle emission surface during the application of the QMB in the tokamak device, the QMB is prone to failure and damage of the quartz crystal due to excessive neutral particle flux under long-pulse high-parameter plasma conditions, and the deposition of impurities on the quartz crystal surface during the plasma discharge process brings calculation errors, etc.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A sleeve for assisting a quartz crystal microbalance in the corrosion study of first wall materials, comprising a metal cylinder with different inner diameters, an insulating base, and a high-voltage power supply. The main parameters of the metal cylinder with different inner diameters include a large inner diameter d1, a small inner diameter d2, and a height h1. There are 4 threaded holes for fixation and one threaded hole for connecting the power line on its side. The insulating base is similar to a structure formed by combining a co-inner-diameter insulating cylinder structure and a different-inner-diameter insulating cylinder structure. There are 4 through holes for fixation on the side of the upper co-inner-diameter insulating cylinder structure, and the metal cylinder with different inner diameters can be fixed on the insulating base using screws. The main parameters of the lower different-inner-diameter insulating cylinder structure include a large inner diameter d3, a small inner diameter d4, and a height h2.

[0011] Further, the material of the metal cylinder with different inner diameters is tungsten or molybdenum.

[0012] Further, the material of the insulating base is boron nitride.

[0013] Further, the outer diameter of the metal cylinder with different inner diameters should be slightly smaller than the inner diameter of the upper co-inner-diameter insulating cylinder structure of the insulating base so that the metal cylinder with different inner diameters can be embedded in the insulating base.

[0014] Further, the small inner diameter d4 of the lower different-inner-diameter insulating cylinder structure of the insulating base is equal to the diameter of the circular coating area on the surface of the quartz crystal.

[0015] Further, the ratio d1 / (h1 + h2) of the large inner diameter d1 and the height h1 of the metal cylinder with different inner diameters to the height h2 of the different-inner-diameter insulating cylinder structure of the insulating base determines the size of the projected area of the circular coating area on the quartz crystal on the plasma surface.

[0016] Further, the projected area of the circular coating area on the quartz crystal on the plasma surface is a partial area on the outermost closed magnetic surface, and the neutral particles emitted from this area can enter the circular coating area on the quartz crystal.

[0017] Further, the value of d1 / (h1 + h2) can be reduced by reducing the large inner diameter d1 of the metal cylinder with different inner diameters or increasing the height h1 to avoid the destruction of the regular shape of the projected area by the nearby pipelines.

[0018] Further, the small inner diameter d2 of the metal cylinder with different inner diameters is equal to the large inner diameter d3 of the lower different-inner-diameter insulating cylinder structure of the insulating base, and (d1 - d2) / h1 is equal to (d3 - d4) / h2.

[0019] Further, the high-voltage power supply fixes the terminal of one end of the wire on the metal cylinder with different inner diameters using screws to maintain the positive bias voltage on the metal cylinder with different inner diameters.

[0020] Further, the amplitude of the positive bias voltage is 100V.

[0021] The beneficial effects of the present invention are embodied in:

[0022] By adopting a metal cylinder with different inner diameters made of tungsten or molybdenum with a high sputtering threshold, in combination with an insulating base and a high-voltage power supply, the present invention can first avoid possible occlusion by adjusting the structural parameters, so that the projection area of the coating area on the quartz crystal on the outermost closed magnetic surface of the plasma is a regular near-circle, which greatly improves the calculation efficiency and accuracy of the average solid angle between the coating area and the projection area. Secondly, installing a sleeve on the QMB can reduce the incident neutral particle flux, lower the rate of temperature rise, and improve the reliability of the QMB operation. Finally, since impurity elements have more extranuclear electrons and are difficult to be neutralized and generally carry positive charges, by applying a positive bias voltage to the metal cylinder with different inner diameters, the deposition of impurities on the surface of the quartz crystal can be effectively prevented. This is of great significance for improving the application of QMB in the magnetic confinement tokamak device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the application of QMB in the magnetic confinement tokamak device after the present invention is installed.

[0024] Figure 2 It is a schematic diagram of the structure of the sleeve in the present invention.

[0025] Figure 3 It is a schematic diagram of the structure of the metal cylinder with different inner diameters.

[0026] Figure 4 It is a schematic diagram of the structure of the insulating base.

[0027] Among them, 1. Metal cylinder with different inner diameters; 2. Insulating base; 3. Probe; 4. Quartz crystal; 5. Electrode flange; 6. High-voltage power supply; 7. LC oscillation circuit; 8. Acquisition system; 9. Projection area; 10. Pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] As Figure 1As shown in the figure, a sleeve of an auxiliary quartz crystal microbalance for the corrosion study of the first wall material according to the present invention includes a metal cylinder 1 with different inner diameters, an insulating base 2, and a high-voltage power supply 6. After the metal cylinder 1 with different inner diameters and the insulating base 2 are assembled together, the whole is fixed in front of the probe 3 of the QMB. The probe 3 is connected to the LC oscillation circuit 7 outside the vacuum chamber through the electrode flange 5, and the LC oscillation circuit 7 is connected to the acquisition system 8.

[0030] As Figure 2 , Figure 3 shown, the main parameters of the metal cylinder 1 with different inner diameters include the large inner diameter d1, the small inner diameter d2, and the height h1. There are 4 threaded holes for fixation and a threaded hole for connecting the power line on the side surface.

[0031] As Figure 2 shown, the material of the metal cylinder 1 with different inner diameters is tungsten or molybdenum.

[0032] As Figure 2 , Figure 4 shown, the insulating base 2 is similar to a structure combining an insulating cylinder with the same inner diameter and an insulating cylinder with different inner diameters. The main parameters of the lower insulating cylinder structure with different inner diameters include the large inner diameter d3, the small inner diameter d4, and the height h2.

[0033] As Figure 3 shown, the material of the insulating base 2 is boron nitride.

[0034] As Figure 2 shown, the outer diameter of the metal cylinder 1 with different inner diameters should be slightly smaller than the inner diameter of the insulating cylinder structure with the same inner diameter above the insulating base 2, so that the metal cylinder 1 with different inner diameters can be embedded in the insulating base 2. The 4 threaded holes for fixation of the metal cylinder 1 with different inner diameters correspond to the 4 through holes for fixation on the side surface of the insulating cylinder structure with the same inner diameter above the insulating base 2, and the metal cylinder 1 with different inner diameters can be fixed on the insulating base 2 by using screws.

[0035] As Figure 1 shown, the small inner diameter d4 of the lower insulating cylinder structure with different inner diameters of the insulating base 2 should be equal to the diameter of the circular coating area on the surface of the quartz crystal 4.

[0036] As Figure 1 shown, the ratio d1 / (h1 + h2) of the large inner diameter d1 and the height h1 of the metal cylinder 1 with different inner diameters to the height h2 of the lower insulating cylinder structure with different inner diameters of the insulating base 2 determines the size of the projected area of the circular coating area on the surface of the quartz crystal 4 on the plasma surface. This projected area is a partial area on the outermost closed magnetic surface, and the neutral particles emitted from this area can enter the circular coating area on the surface of the quartz crystal 4.

[0037] As Figure 1As shown, the pipe 10 will block the projection area of the circular coating area on the surface of the quartz crystal 4 on the plasma surface. The value of d1 / (h1 + h2) can be reduced by decreasing the large inner diameter d1 of the stepped inner diameter metal cylinder 1 or increasing the height h1, so as to avoid the damage of the pipe 10 to the shape of the projection area and obtain a regular near-circular projection area.

[0038] As Figure 2 shown, the small inner diameter d2 of the stepped inner diameter metal cylinder 1 is equal to the large inner diameter d3 of the stepped inner diameter insulating cylinder structure below the insulating base 2, and (d1 - d2) / h1 is equal to (d3 - d4) / h2.

[0039] As Figure 1 shown, the stepped inner diameter metal cylinder 1 in the vacuum chamber is connected to the high-voltage power supply 6 outside the vacuum chamber through the electrode flange 5 to maintain a positive bias voltage of 100V on the stepped inner diameter metal cylinder.

[0040] After the plasma discharge experiment starts, as Figure 1 shown, the positively charged impurity ions are blocked outside the sleeve under the action of the positive bias voltage on the surface of the stepped inner diameter metal cylinder 1. The neutral particles emitted from the area outside the projection area 9 of the circular coating area on the surface of the quartz crystal 4 passing through the sleeve on the outermost closed magnetic surface of the plasma are blocked by the stepped inner diameter metal cylinder 1. Some of the neutral particles emitted from the projection area 9 can pass through the stepped inner diameter metal cylinder 1 and the insulating base 2 and enter the circular coating area on the surface of the quartz crystal 4, mainly causing a reduction in the material quality of the circular coating area on the surface of the quartz crystal 4 through physical sputtering, resulting in a change in the resonance frequency of the quartz crystal. The LC oscillation circuit 7 connected to the quartz crystal 4 outputs the corresponding electrical signal to the acquisition system 8 and records it. A relatively complex solid angle calculation can be simplified to the average solid angle problem of coaxial disks, making the calculation result more accurate and reducing the incident flux of neutral particles at the same time.

[0041] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A sleeve for assisting a quartz crystal microbalance in the corrosion study of first wall materials, characterized in that, It includes a metal cylinder with different inner diameters, an insulating base, and a high-voltage power supply; the parameters of the metal cylinder with different inner diameters include a large inner diameter d1, a small inner diameter d2, and a height h1. There are 4 threaded holes for fixation and one threaded hole for connecting the power cord on the side. The insulating base is a structure combined by a cylindrical insulating structure with the same inner diameter and a cylindrical insulating structure with different inner diameters. There are 4 through holes for fixation on the side of the upper cylindrical insulating structure with the same inner diameter. The metal cylinder with different inner diameters is fixed on the insulating base by screws. The parameters of the lower cylindrical insulating structure with different inner diameters include a large inner diameter d3, a small inner diameter d4, and a height h2; The small inner diameter d4 of the lower cylindrical insulating structure with different inner diameters of the insulating base is equal to the diameter of the circular coating area on the surface of the quartz crystal; The ratio of the large inner diameter d1 of the metal cylinder with different inner diameters, the height h1, and the height h2 of the insulating cylinder structure with different inner diameters of the insulating base determines the size of the projected area of the circular coating area on the quartz crystal on the outermost closed magnetic surface of the plasma, and is reduced by reducing the large inner diameter d1 of the metal cylinder with different inner diameters or increasing the height h1 of the value to avoid the destruction of the regular near-circular projection area by the pipeline; The small inner diameter d2 of the metal cylinder with different inner diameters is equal to the large inner diameter d3 of the insulating cylinder structure with different inner diameters in the insulating base, and is equal to each other.

2. The sleeve for assisting a quartz crystal microbalance in the corrosion study of a first wall material according to claim 1, wherein The material of the metal cylinder with different inner diameters is tungsten or molybdenum.

3. A sleeve for an auxiliary quartz crystal microbalance used in the corrosion study of the first wall material according to claim 1, characterized in that, The material of the insulating base is boron nitride.

4. A sleeve for an auxiliary quartz crystal microbalance used in the corrosion study of the first wall material according to claim 1, characterized in that, The outer diameter of the metal cylinder with different inner diameters is slightly smaller than the inner diameter of the upper cylindrical insulating structure with the same inner diameter of the insulating base, so that the metal cylinder with different inner diameters can be embedded and fixed on the insulating base.

5. A sleeve for an auxiliary quartz crystal microbalance used in the corrosion study of the first wall material according to claim 1, characterized in that, The metal cylinder with different inner diameters is connected to the high-voltage power supply to apply a positive bias voltage, forming a local electric field that can decelerate impurity ions and preventing the impurity ions from incident on the circular coating area on the quartz crystal through the sleeve.

6. A sleeve for an auxiliary quartz crystal microbalance used in the corrosion study of the first wall material as claimed in claim 1, characterized in that, The positive bias voltage is +100 V.

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