CN112779505B - Laser steady-state evaporation coating system and method for high-melting-point material in fusion device - Google Patents

Abstract

The invention discloses a laser steady-state evaporation coating system and method for high melting point materials in a fusion device. The system includes a laser, a laser incident window system, a retractable crucible system and a gas component monitoring system. The laser beam generated by the laser is irradiated to the surface of the high melting point material in the crucible through the laser incident window system, and the steady state evaporation of the high melting point material is realized by adjusting the power density of the laser spot. The invention cooperates with the plasma-assisted vapor deposition in the fusion device to form a uniform thin film on the surface of the first wall of the fusion device. The laser incident window system monitors the air pressure in the vacuum chamber between the two vacuum observation windows, which can avoid the vacuum leakage of the fusion device caused by the damage of the vacuum observation window by the laser beam; to the content in the plasma, so as to remind the operator to replace the high melting point material in time, and effectively avoid the damage of the laser to the crucible.

Description

Laser steady-state evaporation coating system and method for high melting point materials in fusion devices

technical field

The invention relates to the steady-state evaporation of high-melting-point materials inside a fusion reactor vacuum chamber, and is suitable for coating the first wall of a fusion device.

Background technique

In the physical experiments of nuclear fusion devices, the high-temperature plasma interacts with the wall, causing the cavity wall to release various impurities into the plasma, resulting in a huge loss of plasma energy. Therefore, effective suppression of impurities in the cavity is one of the major problems that must be solved to achieve controlled thermonuclear fusion. Excessive hydrogen recirculation levels can easily lead to uncontrollable plasma density, which can easily exceed the Greenwald density limit and eventually lead to plasma rupture. In the H-mode plasma discharge, the recirculation will affect the boundary transport barrier, which will affect the H-mode discharge, so the recirculation control of hydrogen and its isotopes is very important for the stable operation of the highly confined plasma. By coating the inner wall of the nuclear fusion vacuum chamber, it can effectively inhibit the escape of metal impurities, oxygen and carbon impurities, effectively reduce the energy loss of plasma discharge, greatly improve the performance of plasma discharge, and reduce fuel recirculation at the same time.

The high melting point coating materials for fusion devices are represented by silicon and boron. Many fusion devices have carried out boronization and silicide wall treatment. The working gas used in boride wall treatment is diborane B ₂ H ₆ , decaborane B ₁₀ H ₁₄ or organic borides such as B(CH ₃ ) ₃ and C ₂ B ₁₀ H ₁₂ (solid state); the working gas used for silicidation is SiH ₄ or SiD ₄ . The level of impurities in the device can be effectively suppressed by boriding the wall, but since the coating raw material used in boriding itself contains hydrogen, a large amount of hydrogen will be deposited on the first wall, and eventually it will be released during plasma discharge. This results in a higher hydrogen recycle and hydrogen-to-deuterium ratio. Experiments have found that after boriding the wall, the density of the plasma and the Dα radiation level are significantly higher than those before boriding, and the ratio of hydrogen to deuterium increases, which is caused by the rich hydrogen in the working gas used. During plasma discharge, a large amount of hydrogen is released into the plasma by isotope exchange, accompanied by a large amount of deuterium retention, resulting in high hydrogen particle recirculation and high fuel particle wall retention after boride wall treatment, It is difficult to reduce the hydrogen-deuterium ratio to less than 25%, and it is impossible to provide the best hydrogen-deuterium ratio conditions for heating a small number of particles. The working gas used during the silicide wall treatment also contains hydrogen, resulting in a significantly higher hydrogen-deuterium ratio than before the silicide wall treatment. After the silicide wall treatment, the hydrogen-deuterium ratio reaches 70% (50% before silicide). In order to reduce the hydrogen-deuterium ratio, after changing the working gas to SiD ₄ , the hydrogen-deuterium ratio can be easily reduced, but it is difficult to reduce the hydrogen-deuterium ratio to less than 20% even if the silicide wall treatment is carried out many times, and the ion gyration is still not achieved. Heating needs.

Moreover, most of the gaseous boron and silicon sources are flammable or toxic, and the exhaust gas is difficult to handle or the processing cost is relatively high. Especially if diborane leaks, a small amount can be fatal.

Contents of the invention

The technical problem to be solved by the present invention is to provide a system capable of realizing steady-state evaporation of high-melting point materials, which is safe and non-toxic compared to the existing silicification and boronization. , The tail gas treatment is simple; the coating formed on the first wall does not introduce impurities such as hydrogen and carbon.

The technical solution of the present invention is a laser steady-state evaporation coating system for high melting point materials in a fusion device, including a laser, a laser incident window system, a retractable crucible system, and a gas composition monitoring system; the laser includes a laser generator and a laser output port , the laser output port is installed on the top of the vacuum chamber of the fusion device, and the laser beam generated by the laser generator is emitted through the laser output port; the scalable crucible system includes a crucible located in the vacuum chamber of the fusion device, and the crucible A high melting point material is placed inside, the high melting point means that the melting point is greater than 1400°C, another marking material is placed between the high melting point material and the inner bottom surface of the crucible; the laser beam emitted by the laser passes through the The laser incident window system irradiates the surface of the high melting point material, and adjusts the power density of the light spot by changing the power of the laser and/or the size of the spot on the surface of the high melting point material, so that the high melting point material can achieve a steady state Evaporation; the gas composition monitoring system is used to monitor the gas composition in the vacuum chamber, and when the composition of the marking material in the gas exceeds a certain threshold, the laser will stop working immediately.

Further, the laser is a continuous semiconductor laser, the power is determined according to the required evaporation rate, and the power density of the laser spot on the surface of the high melting point material is 5.0×10 ⁴ to 1.0×10 ⁶ W/cm ² ; The laser output port walks along the path set by the program, but the laser spot cannot exceed the upper surface of the high melting point material.

Further, the laser incident window system includes a first laser vacuum observation window and a second laser vacuum observation window, a high vacuum solenoid valve with a leak rate of less than 1×10 ^-9 Pa.m ³ /s, the first laser The vacuum observation window and the second laser vacuum observation window can pass through the laser beam generated by the laser; between the first laser vacuum observation window and the second laser vacuum observation window is a first vacuum chamber, and the first vacuum The chamber is equipped with an exhaust pipe, and there is a vacuum gauge with a range of 1×10 ^-6 ~ 1.0×10 ⁵ Pa on the exhaust pipe; the high-vacuum laser incident window system is located on the top of the fusion device vacuum chamber, and passes through the The high vacuum solenoid valve is connected with the vacuum chamber of the fusion device;

When the steady-state evaporation experiment starts, the first vacuum chamber is evacuated through the exhaust pipe, and the air pressure is maintained at 1×10 ^-5 ~ 9×10 ^-5 Pa. When the air pressure in the first vacuum chamber exceeds 9× 10 ^-5 Pa, the laser stops working immediately, and the high vacuum solenoid valve is closed at the same time;

Between the laser vacuum observation window and the high-vacuum solenoid valve is a second vacuum chamber with a blowing port and a pumping port; the high-vacuum solenoid valve is in an open state when the laser is evaporated in a steady state, and the laser can pass through ; After the laser steady-state evaporation ends, the high-vacuum solenoid valve is in a closed state; during the laser steady-state evaporation, the gas is purged through the blowing interface to reduce the pollution of the laser vacuum observation window.

Further, the radius of the laser-transmitting area of the first laser vacuum observation window and the second laser vacuum observation window is larger than the radius of the evaporation crucible.

Further, the temperature resistance of the material of the evaporating crucible is greater than the melting point of the high melting point material; the vapor evaporated in a steady state is generated by ion cyclotron radio frequency ICRF to generate plasma-assisted vapor deposition, and deposited on the first wall surface of the fusion device; The marking material contains elements different from the high melting point material; the melting point of the marking material is lower than that of the high melting point material; both the high melting point material and the marking material are in block shape, and the sum of the heights of the two is smaller than that of the crucible inner wall height.

Further, the gas composition monitoring system includes a gas phase mass spectrometer and a data processing feedback device; the data collected by the gas phase mass spectrometer is sent to the data processing feedback device for analysis, and when the composition of the marker material in the gas exceeds a certain threshold, the The data processing feedback device issues an instruction, and the laser stops working.

Further, by adjusting the power of the laser and/or the size of the laser spot irradiated on the surface of the high-melting point material, the power density of the laser spot is adjusted to the required range, so that the surface of the high-melting point material only melts and is accompanied by evaporation; the evaporation rate can be controlled by the spot total power and/or power density to control;

Further, the crucible advances or retreats to a set position in the vacuum chamber of the fusion device through the compression and stretching of the bellows.

According to another aspect of the present invention, a method for coating a high melting point material with a laser steady-state evaporation coating system is proposed, comprising the following steps:

Step 1. The working gas is fed into the vacuum chamber of the fusion device, and the plasma discharge is generated by the ion cyclotron radio frequency (ICRF). The crucible is compressed by the bellows and advances to the designated position in the device; Evacuate and maintain the air pressure at 1×10 ^-5 ~ 9×10 ^-5 Pa, turn on the high vacuum solenoid valve and the laser, and the beam emitted by the laser irradiates the surface of the high melting point material in the crucible through the high vacuum laser incident window system; Set the air pressure threshold in the first vacuum chamber. The air pressure threshold is 9×10 ^-5 Pa. In the subsequent steps, the air pressure in the first vacuum chamber is monitored in real time. When the air pressure is higher than the threshold, the laser immediately Stop working, and the high vacuum solenoid valve is closed at the same time;

Step 2. Set the trajectory of the laser output port so that the light spot moves on the surface of the high melting point material;

Step 3. By adjusting the power of the laser and/or the size of the laser spot on the surface of the high-melting point material, adjust the power density of the laser spot to the required range, so that the surface of the high-melting point material only melts and evaporates; the evaporation rate can be controlled by the spot The total power and/or power density is controlled; the evaporated material is ionized by the plasma generated by ICRF in the device, and diffuses to the first wall under the action of uniform ICRF plasma-assisted vapor deposition in the circumferential direction, so as to realize the uniformity of the first wall Coating; when the high melting point material is partially perforated due to evaporation, the marking material under it will be evaporated by the laser and enter the plasma;

Step 4, the gas phase mass spectrometer is connected to the data processing feedback device to detect the value of the marking material composition, and when the marking material composition increases to a certain set threshold value, the data processing feedback device sends an instruction to the laser to stop working;

Step 5. After the laser steady-state evaporation coating experiment of the high-melting point material is completed, the crucible is retracted to a designated position in the device through the stretching of the bellows.

Advantage and positive effect of the present invention:

Low-melting-point materials in existing fusion devices, such as lithium, use evaporative coating, and there is no evaporative coating system and method for high-melting point materials. The system and method of the present invention provide a system and method capable of realizing steady-state evaporation coating of high-melting point materials, and compared with the existing siliconization and boronization realized by gaseous source materials, it is safe and non-toxic; source materials do not exist Safety problems caused by leakage. During the coating process, impurities such as hydrogen and carbon are not introduced. The air pressure monitoring of the laser incident window system can avoid the vacuum leakage of the fusion device caused by the damage of the vacuum observation window by the laser beam; the real-time monitoring of the gas phase composition of the coating process in the fusion device can effectively avoid the laser beam caused by the evaporation and perforation of high melting point materials. Damage the bottom of the crucible and remind the experimenter to replace the high melting point material.

Description of drawings

Figure 1: Schematic diagram of the system structure of the present invention.

in:

Laser 1, laser incident window system 2, retractable crucible system 3, gas composition monitoring system 4;

Laser generator 11, laser output port 12;

The first laser vacuum observation window 21, the second laser vacuum observation window 22, the exhaust pipe 23, the vacuum gauge 24, the first vacuum chamber 25, the high vacuum solenoid valve 26, the air blowing interface 27, the air extraction interface 28, the first Two vacuum chambers 29;

Crucible 31, high melting point material 32, marking material 33, bellows 34;

Gas phase mass spectrometer 41 , data processing feedback device 42 .

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

According to an embodiment of the present invention, the present invention describes a laser steady-state evaporation system for high melting point materials (especially silicon and boron materials, melting points are 1414°C and 2180°C respectively) for the preparation of the first wall coating of a fusion device. In general, by adjusting the high energy density of the laser spot within a certain range, it is possible to melt high-melting point materials and achieve steady-state evaporation. The evaporated vapor is evenly coated on the surface of the first wall through the plasma-assisted vapor deposition in the fusion device, so as to realize the suppression of impurities and the control of recirculation. The air pressure monitoring of the laser incident window system avoids the vacuum leakage of the fusion device caused by the laser beam damaging the vacuum observation window. And the marking material is ingeniously installed between the inner bottom of the retractable crucible and the high melting point material. When the laser melts through the high melting point material, the marking material will be melted and evaporated without damaging the retractable crucible. At the same time, the marking material will enter the plasma and be monitored in real time by the gas composition monitoring system, so that it is known that the high melting point material in the retractable crucible needs to be replaced, and the laser is stopped to avoid damage to the crucible, thus ensuring the safety and stability of the system run.

Figure 1 schematically represents a laser steady-state evaporation system for high-melting-point materials for fusion devices. It includes a laser 1, a laser incident window system 2, a retractable crucible system 3 and a gas composition monitoring system 4; the laser 1 is installed on the top of the vacuum chamber of the fusion device, and the laser beam is generated from the laser generator 11 and passes through the laser output port 12. The lenses converge and shoot out; the telescopic crucible system 3 includes a telescopic crucible 31 located in the vacuum chamber of the fusion device, and a high melting point material 32 to be evaporated in a steady state is placed inside the telescopic crucible 31, and the high melting point material Another marking material 33 is also placed between 32 and the inner bottom of the telescopic crucible 31; the melting point of the marking material 33 is lower than that of the high melting point material 32; the telescopic crucible 31 can pass through the bellows 34 The tension and compression of the laser device enters the set position or retreats to the position behind the limiter of the fusion device; the laser light emitted by the laser 1 is irradiated to the surface of the high melting point material 32 through the laser incident window system 2, by changing The power of the laser 1 and the size of the spot on the surface of the high-melting point material 32 are adjusted to adjust the power density of the spot so that the high-melting point material 32 can achieve steady-state evaporation; the gas composition monitoring system 4 is used to monitor gas composition, when the composition of the marking material 33 in the gas exceeds a certain threshold, the laser 1 stops working.

The laser output port 12 of the laser 1 is located on the top outside the vacuum chamber of the fusion device. The laser spot passes through the laser incident window system 2 and irradiates to the surface of the high melting point material 32 located in the retractable crucible 31 .

The laser generator 11 uses a semiconductor laser. Due to the uniform light intensity distribution of semiconductor lasers, it is easier to achieve uniform and stable evaporation. According to the characteristics of the interaction between the laser and the material, the power density of the laser spot is in the range of 5×10 ⁴ ~1×10 ⁶ W/cm ² , the material will melt, but there will be no violent liquid droplets ejected from the molten pool. Thus, steady-state evaporation is achieved. By adjusting the power of the laser 1 and/or irradiating the laser spot size on the surface of the high-melting point material 32, the power density of the laser spot is adjusted to the required range, so that the surface of the high-melting point material only melts and is accompanied by evaporation; power and/or power density to control. The spot size of the laser beam irradiated on the surface of the high melting point material 32 can be realized by changing the laser output port 12 with different lenses or lens groups and adjusting the distance between the laser output port 12 and the high melting point material 32 . While increasing the evaporation rate as much as possible, ensure steady evaporation. According to the tests of the present invention, for silicon materials, when the laser power is 2500W and the spot diameter is 0.9mm, (the power density at this time is 3.9×10 ⁵ W/cm ² ), the evaporation rate of silicon is 0.8mg/s, It can meet the coating rate requirements in the EAST fusion device.

The laser output port can move according to the set program, so that after the light spot moves on the surface of the high melting point material, the high melting point material can be fully utilized as much as possible. When the high melting point material is locally perforated due to evaporation, the marking material 33 located below it will be evaporated by the laser and thus enter the plasma. At this time, the gas phase mass spectrometer 41 of the real-time composition monitoring system will detect an increase in the composition of the marker material. The gas phase mass spectrometer 41 is connected with the data processing feedback device 42, and when the composition of the marking material 33 increases to a certain set threshold, the data processing feedback device 42 sends an instruction to the laser 1 to stop working. Therefore, the presence of the marking material 33 can effectively prevent the laser from damaging the crucible 31 while reminding the operator to replace the high melting point material.

During the evaporation process of the second laser vacuum observation window 22 of the laser incident window system 2, even if there is an air blowing interface 25 for purging by blowing gas, the high melting point material may gradually accumulate over time. 32 is deposited on the lower surface of the second laser vacuum observation window 22, thereby affecting the penetration effect of the laser beam, and even the laser will damage the second vacuum observation window 22, thereby destroying the vacuum environment of the fusion device. The first laser vacuum viewing window 21 may also be damaged by laser light due to contamination or other reasons.

Because fusion experiments have high requirements on vacuum, once the vacuum is seriously leaked due to this reason, it will take a long time to recover. Therefore, when the second laser vacuum observation window 22 or the first laser vacuum observation window 21 is damaged and leaks, the air pressure of the vacuum chamber 25 will increase. At this time, the high vacuum gauge will send a signal to the data processing feedback device 42 that the detected pressure suddenly rises and exceeds a certain set threshold. The data processing feedback device 42 sends an instruction to the laser 1 to stop working. The laser incident window system 2 can effectively avoid the risk of vacuum leakage due to the laser evaporation system.

According to an embodiment of the present invention, a method for coating a high melting point material in a laser steady-state evaporation coating system of the present invention includes the following steps:

Step 1. The working gas is introduced into the vacuum chamber of the fusion device, and the plasma discharge is generated by the ion cyclotron radio frequency (ICRF). The crucible 31 is compressed by the bellows 34 and advances to the designated position in the device; The exhaust pipe 23 pumps air, and maintains the air pressure at 1×10 ^-5 ~ 9×10 ^-5 Pa, and sets the air pressure threshold in the first vacuum chamber, which is 9×10 ^-5 Pa. In the subsequent steps , monitor the air pressure value in the first vacuum chamber in real time, when the air pressure value is higher than the threshold value, the laser will stop working immediately, and the high vacuum solenoid valve will be closed; the high vacuum solenoid valve and the laser will be turned on, and the beam emitted by the laser will pass through the high vacuum The laser incident window system 2 irradiates the surface of the high melting point material in the crucible;

Step 2. Set the trajectory of the laser output port so that the light spot moves on the surface of the high melting point material;

Step 3, by adjusting the power of the laser 1 and/or irradiating the laser spot size on the surface of the high melting point material 32, adjust the power density of the laser spot to the required range, so that the surface of the high melting point material only melts and is accompanied by evaporation; the evaporation rate can be passed The total power and/or power density of the spot is controlled; the evaporated material is ionized by the plasma generated by ICRF in the device, and diffuses to the first wall under the action of uniform ICRF plasma-assisted vapor deposition in the circumferential direction to realize the first wall uniform coating; when the high melting point material is partially perforated due to evaporation, the marking material 33 located below it will be evaporated by the laser, thereby entering the plasma;

Step 4, the gas phase mass spectrometer 41 is connected with the data processing feedback device 42 to detect the value of the marking material 33 composition in the gas, and when the marking material 33 composition increases to a certain threshold value, the data processing feedback device 42 sends a stop working signal to the laser 1 instruction;

Step 5: After the laser steady-state evaporation coating experiment of the high-melting point material is finished, the crucible 31 is stretched by the bellows 34 and retracted to a designated position in the device.

Although the illustrative specific embodiments of the present invention have been described above, so that those skilled in the art can understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, As long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

Claims (8)

1. A laser steady-state evaporation coating system for high melting point materials in a fusion device, characterized in that it includes a laser (1), a laser incident window system (2), a retractable crucible system (3) and a gas composition monitoring system (4) The laser (1) includes a laser generator (11) and a laser output port (12), and the laser output port (12) is installed on the top of the vacuum chamber of the fusion device, and the laser generated by the laser generator (11) The beam is emitted through the laser output port (12); the scalable crucible system (3) includes a crucible (31) located in the vacuum chamber of the fusion device, and a high melting point material (32) is placed inside the crucible (31), so The high melting point means that the melting point is greater than 1400°C, and another marking material (33) is placed between the high melting point material (32) and the inner bottom surface of the crucible (31); the laser light emitted by the laser (1) The beam is irradiated onto the surface of the high melting point material (32) through the laser incident window system (2), by changing the power of the laser (1) and/or the size of the spot on the surface of the high melting point material (32) , adjust the power density of the light spot, so that the high melting point material (32) realizes steady-state evaporation; the gas composition monitoring system (4) is used to monitor the gas composition in the vacuum chamber, when the composition of the marking material (33) in the gas exceeds a certain When a threshold value is reached, the laser (1) stops working immediately; The laser incident window system (2) includes a first laser vacuum observation window (21) and a second laser vacuum observation window (22), a high vacuum solenoid valve with a leak rate of less than 1×10 ^-9 Pa·m ³ /s (26), the first laser vacuum observation window (21) and the second laser vacuum observation window (22) can pass through the laser beam generated by the laser (1); the first laser vacuum observation window (21) Between the second laser vacuum observation window (22) is the first vacuum chamber (25), the first vacuum chamber (25) has an air extraction pipeline (23), on the air extraction pipeline (23) There is a vacuum gauge (24) with a measuring range of 1×10 ^-6 ~ 1.0×10 ⁵ Pa; the laser incident window system (2) is located on the top of the vacuum chamber of the fusion device, and passes through the high vacuum electromagnetic valve (26) and The vacuum chamber of the fusion device is connected; The first vacuum chamber (25) is pumped through the pumping pipe (23), and the air pressure is maintained at 1×10 ^-5 ~ 9×10 ^-5 Pa. When the air pressure in the first vacuum chamber (25) exceeds 9×10 ^-5 Pa, the laser (1) stops working immediately, and the high vacuum solenoid valve (26) is closed at the same time; Between the second laser vacuum observation window (22) and the high vacuum solenoid valve (26) is a second vacuum chamber (29) with an air blowing interface (27) and an air extraction interface (28); The high-vacuum electromagnetic valve (26) is in an open state during steady-state evaporation, and the laser can pass through; the high-vacuum electromagnetic valve (26) is in a closed state after the laser steady-state evaporation ends; The air interface (27) is purged to reduce the pollution of the second laser vacuum observation window (22). 2. The laser steady-state evaporation coating system for high melting point materials in a fusion device according to claim 1, characterized in that: the laser is a continuous semiconductor laser, the power is determined according to the required evaporation rate, and the laser is in the The power density of the light spot generated on the surface of the high melting point material (32) is 5.0×10 ⁴ ~1.0×10 ⁶ W/cm ² ; the laser output port (12) follows the path set by the program, but the laser spot cannot exceed the The upper surface of the high melting point material (32). 3. The laser steady-state evaporation coating system for high melting point materials in a fusion device according to claim 2, characterized in that: the first laser vacuum observation window (21) and the second laser vacuum observation window (22) can The radius of the laser-transmitting region is greater than the radius of the crucible (31). 4. The laser steady-state evaporation coating system for high melting point materials in a fusion device according to claim 1, characterized in that: the temperature resistance of the material of the crucible (31) is greater than the melting point of the high melting point material (32); Steady-state evaporated vapor generates plasma-assisted vapor deposition through ion cyclotron radio frequency wave ICRF, and is deposited on the first wall surface of the fusion device; the marking material (33) contains elements different from the high melting point material; the The melting point of the marking material (33) is lower than the melting point of the high melting point material (32); the high melting point material (32) and the marking material (33) are both block-shaped, and the sum of the heights of the two is less than the height of the inner wall of the crucible . 5. The laser steady-state evaporation coating system for high melting point materials in a fusion device according to claim 1, characterized in that: the gas composition monitoring system (4) includes a gas phase mass spectrometer (41) and a data processing feedback device (42 ); the data collected by the gas phase mass spectrometer (41) is sent to the data processing feedback device (42) for analysis, and when the composition of the marker material (33) in the gas exceeds a certain threshold value, the data processing feedback device (42) When an instruction is issued, the laser (1) stops working. 6. The laser steady-state evaporation coating system for high melting point materials in a fusion device according to claim 1, characterized in that: by adjusting the power of the laser (1) and/or irradiating the laser spot on the surface of the high melting point material (32) Size, adjust the power density of the laser spot to the required range, so that only the surface of the high melting point material is melted and accompanied by evaporation, and no melt is ejected. 7. The laser steady-state evaporation coating system for high-melting-point materials in a fusion device according to claim 1, characterized in that: the crucible (31) is compressed and stretched by the bellows (34) so that the fusion device Advance or retreat to the set position in the vacuum chamber. 8. A laser steady-state evaporation coating method for high melting point materials in a fusion device, characterized in that it comprises the following steps: Step 1. The working gas is introduced into the vacuum chamber of the fusion device, and the plasma discharge is generated by the ion cyclotron radio frequency (ICRF). The crucible (31) advances to the designated position in the device through the compression of the bellows (34); the first vacuum chamber (25) Pump air through the suction pipe (23), and maintain the air pressure at 1×10 ^-5 ~ 9×10 ^-5 Pa, open the high-vacuum solenoid valve and the laser, and the beam emitted by the laser passes through the laser incident window system (2 ) irradiates the surface of the high-melting point material in the crucible; the air pressure threshold in the first vacuum chamber (25) is set, and the air pressure threshold is 9×10 ^-5 Pa. In subsequent steps, the first vacuum chamber ( 25) internal air pressure value, when the air pressure value is higher than the threshold value, the laser (1) stops working immediately, and the high vacuum solenoid valve (26) is closed simultaneously; Step 2. Set the trajectory of the laser output port so that the light spot moves on the surface of the high melting point material; Step 3. By adjusting the power of the laser (1) and/or irradiating the laser spot size on the surface of the high melting point material (32), the power density of the laser spot is adjusted to the required range, so that the surface of the high melting point material is only melted and accompanied by evaporation, No melt ejection; the evaporation rate is controlled by the total power and/or power density of the spot; the evaporated material is ionized by the plasma generated by ICRF in the device, and dispersed under the action of annular uniform ICRF plasma-assisted vapor deposition to the first wall to achieve a uniform coating on the first wall; when the high melting point material is partially perforated due to evaporation, the marking material (33) located below it will be evaporated by the laser, thereby entering the plasma; Step 4, the gas phase mass spectrometer (41) is connected with the data processing feedback device (42) to detect the component value of the marker material (33) in the gas, and when the component value of the marker material (33) increases to a certain set threshold value, the data The processing feedback device (42) sends an instruction to the laser (1) to stop working; Step 5. After the laser steady-state evaporation coating experiment of high-melting point materials is completed, the crucible (31) is stretched by the bellows (34) and retracted to a designated position in the device.

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