A vacuum pumping system for a powder-containing chamber in a fusion device

Abstract

The present invention provides a vacuum pumping system for a powder-containing chamber in a fusion device, comprising a powder-containing chamber, a main pumping pipeline, a side pumping branch I, a side pumping branch II, and a vacuum pumping unit. The present invention uses a vacuum needle valve with a flow coefficient Cv of 0.37 and a pipeline with an inner diameter of Φ4.4mm on the side pumping branch II to control the airflow of the powder-containing chamber in a stable state during the initial vacuum pumping; then uses a pipeline with an inner diameter of Φ16mm on the side pumping branch I to provide a large flow conductance, thereby achieving high vacuum in the powder chamber, avoiding the powder in the chamber from floating around with the fluctuation of the airflow, avoiding the mutual mixing of different powders, and finally achieving real-time injection of low atomic number powder materials into the fusion device, and achieving real-time wall treatment and boundary local mode control of plasma discharge.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear fusion tokamaks, and mainly to a vacuum pumping system containing a powder chamber. Background Art

[0002] In the magnetic confinement nuclear fusion tokamak device, solid powdered low atomic number materials are widely used in the real-time wall treatment of the first wall and the control of boundary localized modes during plasma discharge. They provide good first wall conditions for high-parameter long-pulse plasma discharge in real time and effectively protect key components such as the divertor target plate from damage caused by the explosion of boundary localized modes.

[0003] At present, many fusion devices at home and abroad are equipped with powder injection systems, such as EAST, DIII-D and LHD. The domestic all-superconducting tokamak EAST device uses real-time continuous injection of lithium powder to successfully obtain steady-state plasma discharge of hundreds of seconds and core temperature exceeding 100 million degrees. The system mainly uses a piezoelectric ceramic plate to generate a resonance effect after receiving a sinusoidal voltage of a specific frequency, thereby driving the powder on the piezoelectric ceramic plate to fall freely under gravity and enter the plasma. However, since the diameter of the powder is only at the micron scale and it is a material with a low atomic number, the mass of these powders is very small and it is easy to be affected by air flow fluctuations and drift around. Especially in the initial vacuum stage of the chamber, the powder can easily enter the vacuum pipeline with the air flow and deposit on the sealing surface of the vacuum valve, contaminating the vacuum valve and posing the risk of vacuum leakage; more seriously, the four different types of powders cannot be mixed during the vacuum period due to air flow fluctuations, resulting in irrelevant powder entering the plasma when the powder is injected in real time during the plasma discharge. Therefore, it is urgent to develop a new type of vacuum system to achieve stable high vacuum in the powder chamber. Summary of the invention

[0004] The purpose of the present invention is to provide a vacuum system for a chamber containing micron-sized powder in a fusion device, so as to ensure the stability of the powder in the chamber, avoid powder contamination of the vacuum valve in the vacuum system, and provide stable low atomic number powder injection for plasma discharge.

[0005] The present invention is achieved through the following technical solutions:

[0006] A vacuum pumping system for a powder-containing chamber in a fusion device, comprising a powder-containing chamber, a main pumping pipeline, a side pumping branch I, a side pumping branch II, and a vacuum pumping unit; the powder-containing chamber is loaded with four different low-atomic-number powder materials, including lithium powder, boron powder, silicon powder, and lithium pellets; the main pumping pipeline is connected to the pumped powder-containing chamber, and comprises a vacuum angle valve a with a diameter of Φ16 mm, a stainless steel pipe with an inner diameter of Φ16 mm, and a stainless steel tee with a diameter of Φ16 mm; the side pumping branch I is connected to the side pumping branch II, and the side pumping branch II .... I is connected to one end of the stainless steel tee on the main exhaust pipeline, and the side exhaust branch I includes a vacuum angle valve b with a diameter of Φ16mm and a stainless steel pipe with an inner diameter of Φ16mm; the side exhaust branch II is connected to the other end of the stainless steel tee on the main exhaust pipeline, including a vacuum needle valve, a stainless steel pipe with an inner diameter of Φ4.4mm and a vacuum angle valve c with a diameter of Φ16mm connected in series; the vacuum exhaust unit is connected to the side exhaust branch I and the side exhaust branch II through a stainless steel tee, and includes a turbomolecular pump and a mechanical pump.

[0007] Furthermore, the powder-containing chamber is a chamber loaded with four different low atomic number micron-scale solid powders, and its inner diameter is Φ200mm; the four different solid powders loaded in the powder-containing chamber are: high-purity lithium powder with a diameter of about Φ40μm and a purity >99.9%; high-purity boron powder with a diameter of about Φ70μm and a purity >99.9%; 100 mesh, high-purity silicon powder with a purity >99.9%; high-purity lithium projectiles with a diameter of Φ700μm and a purity >99.9%.

[0008] Furthermore, the wall thickness of the stainless steel pipe of the main exhaust pipeline is 1.5 mm, and the leakage rate of the vacuum angle valve a is less than 1.3×10 -7 Pa·L / s, used for the isolation and connection between the powder-containing chamber and the rear-end vacuum pumping unit.

[0009] Furthermore, the wall thickness of the stainless steel pipe of the bypass air extraction branch I is 1.5 mm, and the leakage rate of the vacuum angle valve b is less than 1.3×10 -7 Pa·L / s, after the initial exhaust in the powder-containing chamber is completed, the vacuum angle valve b on the side exhaust branch I is opened to provide an exhaust branch with greater conductance for the powder-containing chamber.

[0010] Furthermore, the wall thickness of the stainless steel pipe of the bypass air extraction branch II is 0.8 mm, the flow coefficient Cv of the vacuum needle valve is 0.37, and the leakage rate of the vacuum angle valve c of the bypass air extraction branch II is <1.3×10 -7Pa·L / s; the side exhaust branch II is an exhaust pipeline connected in parallel with the side exhaust branch I. When the powder-containing chamber is initially exhausted, a vacuum needle valve is used to slowly reduce the vacuum degree in the powder-containing chamber, thereby ensuring a stable airflow in the powder-containing chamber and avoiding large fluctuations in the airflow in the powder-containing chamber, which may cause powder to float around in the powder-containing chamber and powder to enter the exhaust pipeline and contaminate the vacuum angle valves and vacuum exhaust unit.

[0011] Furthermore, the vacuum pumping unit is connected to the side pumping branch I and the side pumping branch II through a stainless steel tee, the pumping speed of the turbomolecular pump is 200L / s, and the pumping speed of the mechanical pump is 20L / s, which is used to provide a vacuum pumping function for the powder-containing chamber.

[0012] Furthermore, the main air extraction pipeline is connected to the powder chamber, and a vacuum angle valve is used to achieve isolation and connection between the powder chamber and the rear-end air extraction system; the side air extraction branch I is connected to one end of the tee at the root of the main air extraction pipeline, mainly to provide a larger air extraction flow conductance for the powder chamber; the side air extraction branch II is connected to the other end of the tee at the root of the main air extraction pipeline, and the vacuum needle valve on the side air extraction branch II is used to provide a smaller flow conductance when the powder chamber is initially evacuated, thereby avoiding large air flow fluctuations in the powder chamber.

[0013] Furthermore, the powder chamber is a stainless steel cylinder with an inner diameter of Φ200mm, a wall thickness of 3mm, and a height of 200mm. There are four powder storage channels with a diameter of Φ30mm, a wall thickness of 0.5mm, and a height of 80mm inside, which are used to load lithium powder, boron powder, silicon powder, and lithium projectiles. A glass observation window flange with a diameter of Φ200mm is installed directly above the powder chamber to achieve vacuum sealing of the chamber and monitoring of the powder state of the chamber.

[0014] Furthermore, the stainless steel pipe of the main exhaust pipeline and the vacuum angle valve are sealed with a Φ16mm diameter knife-edge flange and an oxygen-free copper sealing ring to ensure the vacuum airtightness requirements on the main exhaust pipeline. The vacuum angle valve is mainly used to separate and connect the powder chamber with the rear-end exhaust system. When the powder chamber is exhausted, the angle valve remains open; when the powder chamber is exhausted and in a high vacuum environment, the angle valve is closed to connect the powder chamber with the fusion device.

[0015] Furthermore, the side exhaust branch I mainly opens the vacuum angle valve b after the powder chamber completes the initial exhaust, so as to provide a larger exhaust gas conduction for the powder chamber and achieve a high vacuum degree in the powder chamber.

[0016] Furthermore, the front end of the Φ4.4mm stainless steel pipe of the side exhaust branch II passes through a blind flange with a knife-edge diameter of Φ16mm and is fully welded to ensure the airtightness of the stainless steel pipe; its tail is connected to a vacuum needle valve with a flow coefficient Cv of 0.37 using a sleeve. The rear end of the vacuum needle valve is also connected to the vacuum angle valve through a blind flange with a knife-edge diameter of Φ16mm using a Φ4.4mm stainless steel pipe, and the rear end of the angle valve is directly connected to the vacuum exhaust unit. The side exhaust branch II is mainly used for the first time to evacuate the powder chamber, to fully open the angle valve, and then slowly control the opening and closing degree of the vacuum needle valve to ensure that the airflow in the powder chamber is stable and the powder chamber is vacuumed.

[0017] Furthermore, the turbomolecular pump mainly provides a higher vacuum environment for the powder chamber. The front stage of the turbomolecular pump is equipped with a mechanical pump with a pumping speed of 20L / s, which is connected in series with the turbomolecular pump. It is mainly used to provide pumping capacity when the powder chamber is first pumped and to start the front stage pump of the molecular pump after the airflow in the powder chamber is stable.

[0018] Furthermore, after the powder chamber vacuum exhaust system completes powder loading in the powder chamber, it opens the vacuum angle valve a on the main exhaust pipeline, closes the vacuum angle valve b on the side exhaust branch I, opens the vacuum angle valve c on the side exhaust branch II, turns on the mechanical pump, and then slowly controls the opening and closing degree of the vacuum needle valve to ensure the stability of the airflow in the powder-containing chamber, thereby finally achieving a vacuum environment in the powder-containing chamber.

[0019] Beneficial effects:

[0020] The present invention provides a simple, economical and effective vacuum pumping system for a powder-containing chamber, which can effectively protect the vacuum valve on the pumping pipeline and avoid contamination by powder deposition. More importantly, it provides a stable vacuum environment and stable powder output for the powder injection system of the fusion device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 This is a schematic diagram of the bypass air branch II.

[0023] In the figure, 1 is a powder chamber; 2 is a main exhaust pipeline; 3 is a vacuum angle valve a; 4 is a side exhaust branch I; 5 is a vacuum angle valve b; 6 is a side exhaust branch II; 7 is a vacuum needle valve; 8 is a vacuum angle valve c; 9 is a turbomolecular pump; 10 is a mechanical pump; 11 is a knife-edge blind flange with a diameter of Φ16mm; 12 is a stainless steel pipe with an inner diameter of Φ4.4mm. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended 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.

[0025] like Figure 1 As shown, a vacuum pumping system for a powder-containing chamber in a fusion device includes a powder-containing chamber 1, a main pumping pipeline 2, a side pumping branch I4, a side pumping branch II6, and a vacuum pumping unit. The powder-containing chamber 1 is a pumped powder-containing chamber of the present invention, and is loaded with four types of micron-level powder materials; the main pumping pipeline 2 is directly connected to the powder-containing chamber 1, and a vacuum angle valve a3 is installed on the pipeline; the side pumping branch I4 is connected to the main pumping pipeline through a stainless steel tee, and a vacuum angle valve b5 is installed on the pipeline; the side pumping branch II6 is connected to the other end of the stainless steel tee on the main pumping pipeline 1, and a vacuum needle valve 7 and a vacuum angle valve c8 are installed in series on the side pumping branch II6; the vacuum pumping unit is connected to the side pumping branch I4 and the side pumping branch II6 through a stainless steel tee, and mainly includes a turbomolecular pump 9 and a mechanical pump 10.

[0026] The powder-containing chamber 1 can be loaded with powders of four different materials. Commonly used powders include lithium powder with a diameter of about Φ40μm, boron powder with a diameter of about Φ70 microns, silicon powder of 100 mesh, and lithium pellets with a diameter of Φ700 microns. The purity of the selected powder materials is greater than 99.9%. Since metallic lithium is very easy to oxidize in the air and spontaneous combustion may occur in a highly humid environment, a plastic glove box is often used when loading lithium powder and lithium pellets. First, the chamber is completely wrapped with a plastic glove box, and then dry argon gas with a purity of >99.99% is filled into the glove box, and multiple exhaust and inflation actions are performed. The humidity in the chamber is measured using a hygrometer. When the humidity is less than <10%, the lithium powder and lithium pellets placed in the plastic glove box in advance can be loaded into the powder chamber. After all four powders are loaded, the glass observation window above the chamber is sealed in the plastic glove box with an oxygen-free copper sealing ring.

[0027] The main exhaust pipe 2 has an inner diameter of Φ16 mm, a wall thickness of 1.5 mm, and is made of stainless steel. It is connected to the powder chamber 1 through a knife-edge flange and an oxygen-free copper sealing ring. A Φ16 mm diameter, leakage rate <1.3×10 -7When the powder-containing chamber 1 is loaded with powder, the vacuum angle valve a3 is opened to fill the vacuum angle valve a3 with high-purity argon gas, so as to avoid a stream of air being stored in the valve, which may cause the air to enter the powder-containing chamber 1 later and cause oxidation of the lithium powder.

[0028] The pipe in the side exhaust branch I4 has an inner diameter of Φ16mm, a wall thickness of 1.5mm, and is made of stainless steel. It is connected to the main exhaust pipe 2 through a stainless steel tee, and also uses a knife-edge flange plus an oxygen-free copper sealing ring to ensure the air tightness of the branch. A Φ16mm diameter pipe with a leakage rate of <1.3×10 -7 When the powder-containing chamber 1 is initially vacuumed, the vacuum angle valve b5 is kept closed; after the initial vacuuming is completed in the powder-containing chamber 1 and the internal vacuum is good, the vacuum angle valve b5 is opened to provide a larger vacuum conduction.

[0029] like Figure 2 As shown, the stainless steel pipe 12 in the side exhaust branch II6 has an inner diameter of Φ4.4mm and a wall thickness of 0.8mm. It is made of stainless steel, and its front end passes through a knife-edge blind flange 11 with a knife-edge diameter of Φ16mm and is fully welded and fixed to ensure the airtightness of the stainless steel pipe 12 with an inner diameter of Φ4.4mm. This flange is used to connect to the other end of the tee at the root of the main exhaust pipeline 2. The rear end of the stainless steel pipe 12 is connected to a vacuum needle valve 7 with a flow coefficient Cv of 0.37 through a sleeve joint, and the rear end of the vacuum needle valve 7 is also connected to the Φ4.4mm stainless steel pipe using a sleeve joint. Similarly, the pipe is welded to a knife-edge flange with a diameter of Φ16mm and a rear diameter of Φ16mm, with a leakage rate of <1.3×10 -7 The rear end of the vacuum angle valve c8 is directly connected to the vacuum pumping unit. When the powder-containing chamber is initially evacuated, the vacuum angle valve c8 is opened, and the vacuum needle valve 7 at the front end is slowly opened to evacuate the powder-containing chamber while ensuring that the airflow in the chamber remains stable.

[0030] The vacuum pumping unit is directly connected to the side pumping branch I4 and the side pumping branch II6 through a stainless steel tee with a diameter of Φ16mm. It mainly includes a 200L / s turbomolecular pump 9 and a 20L / s mechanical pump 10. When the powder-containing chamber 1 is initially pumped, only the mechanical pump 10 is turned on to provide vacuum pumping capacity for the powder-containing chamber 1. When the vacuum in the powder-containing chamber 1 satisfies the turbomolecular pump 9 start-up, the turbomolecular pump 9 can be directly turned on to obtain a better vacuum environment.

[0031] The specific working process of the vacuum exhaust system of the powder-containing chamber is as follows: first, open all valves in the system, open the mechanical pump 10 to exhaust the atmosphere on all exhaust pipes, then close all valves on the side exhaust branch I4 and the side exhaust branch II6, and keep the vacuum angle valve a3 on the main exhaust pipe 2 open. Then, complete the loading of the powder in the powder-containing chamber 1 under the argon environment, and encapsulate the glass observation window just above the chamber under the argon environment. Then open the vacuum angle valve c8 on the side exhaust branch II6, and then slowly open the vacuum needle valve 7 on the side exhaust branch II6 while observing the powder state through the glass observation window above the chamber, and slowly open the vacuum needle valve 7 to ensure that the powder in the chamber does not flow, until the vacuum needle valve 7 is fully opened. After the vacuum needle valve 7 is fully opened, open the vacuum angle valve b5 on the side exhaust branch I4, turn on the turbomolecular pump 9, and complete the acquisition of the high vacuum environment of the powder chamber.

[0032] It will be easily understood by those skilled in the art 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 substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A vacuum pumping method for a vacuum pumping system of a powder-containing chamber in a fusion device, characterized in that: The invention comprises a powder-containing chamber, a main exhaust pipeline, a side exhaust branch I, a side exhaust branch II, and a vacuum exhaust unit; the powder-containing chamber is loaded with four different low-atomic-number powder materials, including lithium powder, boron powder, silicon powder, and lithium pellets; the main exhaust pipeline is connected to the exhausted powder-containing chamber, and comprises a vacuum angle valve a with a diameter of Φ16 mm, a stainless steel pipe with an inner diameter of Φ16 mm, and a stainless steel tee with a diameter of Φ16 mm; the side exhaust branch I is connected to one end of the stainless steel tee on the main exhaust pipeline, and the side exhaust branch I comprises a vacuum angle valve b with a diameter of Φ16 mm and a stainless steel pipe with an inner diameter of Φ16 mm. mm stainless steel pipeline; the side exhaust branch II is connected to the other end of the stainless steel tee on the main exhaust pipeline, including a vacuum needle valve, a stainless steel pipeline with an inner diameter of Φ4.4mm and a vacuum angle valve c with a diameter of Φ16mm in series; the vacuum exhaust unit is connected to the side exhaust branch I and the side exhaust branch II through a stainless steel tee, and includes a turbomolecular pump and a mechanical pump; First, open all the valves in the system, turn on the mechanical pump to remove the atmosphere from all the exhaust pipes, then close all the valves on the side exhaust branch I and the side exhaust branch II, and keep the vacuum angle valve a on the main exhaust pipe open; then complete the loading of the powder in the powder chamber 1 under the argon environment, and encapsulate the glass observation window just above the chamber under the argon environment; then open the vacuum angle valve c on the side exhaust branch II, then slowly open the vacuum needle valve on the side exhaust branch II while observing the powder state through the glass observation window above the chamber, and slowly open the vacuum needle valve to ensure that the powder in the chamber does not flow, until the vacuum needle valve is fully opened; after the vacuum needle valve is fully opened, open the vacuum angle valve b on the side exhaust branch I, turn on the turbomolecular pump, and complete the acquisition of a high vacuum environment in the powder chamber.

2. The vacuum pumping method according to claim 1, characterized in that: The powder-containing chamber is a stainless steel cylinder loaded with four different low atomic number micron-scale solid powders, and its inner diameter is Φ200 mm; the four different solid powders loaded in the powder-containing chamber are: high-purity lithium powder with a diameter of Φ40 μm and a purity of >99.9%; high-purity boron powder with a diameter of about Φ70 μm and a purity of >99.9%; high-purity silicon powder with a mesh size of 100 and a purity of >99.9%; and high-purity lithium pellets with a diameter of Φ700 μm and a purity of >99.9%.

3. The vacuum pumping method according to claim 1, characterized in that: The wall thickness of the stainless steel pipe of the main exhaust pipeline is 1.5 mm, and the leakage rate of the vacuum angle valve a is less than 1.3×10 -7 Pa·L / s, used for the isolation and connection between the powder-containing chamber and the rear-end vacuum pumping unit.

4. The vacuum pumping method according to claim 1, characterized in that: The wall thickness of the stainless steel pipe of the bypass air extraction branch I is 1.5 mm, and the leakage rate of the vacuum angle valve b is <1.3×10 -7 Pa·L / s, after the initial exhaust in the powder-containing chamber is completed, the vacuum angle valve b of the side exhaust branch I is opened to provide an exhaust branch with greater flow conductance for the powder-containing chamber.

5. The vacuum pumping method according to claim 1, characterized in that: The wall thickness of the stainless steel pipe of the bypass air extraction branch II is 0.8 mm, the flow coefficient Cv of the vacuum needle valve is 0.37, and the leakage rate of the vacuum angle valve c of the bypass air extraction branch II is <1.3×10 -7 Pa·L / s; the side exhaust branch II is an exhaust pipeline connected in parallel with the side exhaust branch I. When the powder-containing chamber is evacuated for the first time, a vacuum needle valve is used to slowly reduce the vacuum degree in the powder-containing chamber, thereby ensuring the stability of the airflow in the powder-containing chamber and avoiding large fluctuations in the airflow in the powder-containing chamber, which may cause powder to float around in the powder-containing chamber and powder to enter the exhaust pipeline and contaminate the vacuum angle valves and vacuum exhaust units.

6. The vacuum pumping method according to claim 1, characterized in that: The vacuum pumping unit is connected to the side pumping branch I and the side pumping branch II through a stainless steel tee. The pumping speed of the turbomolecular pump is 200L / s, and the pumping speed of the mechanical pump is 20L / s, which is used to provide a vacuum pumping function for the powder-containing chamber.

7. The vacuum pumping method according to claim 1, characterized in that: The main exhaust pipeline uses a vacuum angle valve a to achieve isolation and connection between the powder-containing chamber and the rear-end vacuum exhaust component; the side exhaust branch I provides a larger exhaust flow conductance for the powder-containing chamber; the side exhaust branch II uses the vacuum needle valve thereon to provide a smaller flow conductance when the powder-containing chamber is initially exhausted, thereby avoiding large airflow fluctuations in the powder-containing chamber.

8. The vacuum pumping method according to claim 2, characterized in that: The powder-containing chamber has four powder storage channels with a diameter of Φ30 mm, a wall thickness of 0.5 mm and a height of 80 mm.

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