CN109751218B

CN109751218B - Built-in high-vacuum low-temperature condensing air pump

Info

Publication number: CN109751218B
Application number: CN201711067659.9A
Authority: CN
Inventors: 李勇; 查方正; 邱银; 卢勇
Original assignee: Southwestern Institute of Physics
Current assignee: Southwestern Institute of Physics
Priority date: 2017-11-03
Filing date: 2017-11-03
Publication date: 2023-10-20
Anticipated expiration: 2037-11-03
Also published as: CN109751218A

Abstract

The invention belongs to the technical field of nuclear fusion, and particularly discloses a built-in high-vacuum low-temperature condensation air pump which is formed into a complete circle by a plurality of sections of circular arc structures, wherein each circular arc structure comprises a heat radiation protection screen, a liquid nitrogen screen, an arc shutter, a nitrogen pipe and a helium pipe; the inside of the arc section of the nitrogen/helium pipe is self-formed into a loop, and the blades of the arc shutter are fixed on the nitrogen pipe at the outer side; the pipelines of the nitrogen pipe, the helium pipe, the heat radiation shielding and the liquid nitrogen shielding are concentric circular arcs. The built-in high-vacuum low-temperature condensation air pump can effectively and timely pump neutral particles, has high pumping speed and small vibration, adopts a shutter design, avoids high-temperature particles to directly strike a liquid helium pipeline, reduces the heat load of the liquid helium pipe, and is compact in structure and convenient to install.

Description

Built-in high-vacuum low-temperature condensing air pump

Technical Field

The invention belongs to the technical field of nuclear fusion, and particularly relates to a built-in condensing and sucking pump for an HL-2M tokamak device.

Background

The normal operation of the tokamak device is very important for controlling the neutral particles, which is one of the necessary requirements for ensuring the plasma quality. The neutral particle control has important influence on constraint improvement, plasma quality, impurity transport, wall material corrosion, target plate heat load, divertor operation, main plasma feeding, safe continuous operation of a fusion reactor core and the like. It can be said that the final goal of the neutral particle control is to improve the plasma confinement. To achieve the goal of improving plasma confinement and improving plasma quality, edge neutrals must be tightly controlled, while to achieve the goal of reducing the thermal load of the divertor target plate, neutrals must be actively added locally, the two goals are reversed, but neutrals must be excluded to be uniform. The neutral particle control is to realize the control of neutral particle pressure by pumping air through an air pumping system when active air supply and passive impurities are generated, so as to achieve the balance between improving plasma constraint, improving plasma quality and reducing the thermal load of a target plate of a divertor.

HL-2M tokamak devices are being built with high plasma parameters, in order to better control the plasma density and expel neutral gases, the pumping system is required to have higher pumping speed, in particular the high parameter discharge requires a larger instantaneous pumping speed and better performance, the vacuum reaches 1.33 x 10 ^-1 ～10 ^-6 Pa, the temperature of the liquid helium pipeline reaches below 4.5K. The common commercial cryopump cannot be applied to the situations of special shape requirements and extremely high pumping speed in an HL-2M device, so that a special cryopump structure is needed, the pumping capacity of the cryopump is maximized, the cryogenic fluid is reasonably distributed and controlled, and the pumping efficiency is improved to meet the requirements.

Disclosure of Invention

The invention aims to provide a built-in high-vacuum low-temperature condensing air pump which can meet the operation requirement of an HL-2M device, is suitable for the operation condition of a severe fusion experimental device, and has higher safety and reliability.

The technical scheme of the invention is as follows:

the utility model provides a built-in high vacuum low temperature condensation aspiration pump, its complete circular of by a plurality of sections circular arc structures constitution, its characterized in that: the arc structure comprises an arc tube formed by a plurality of sections of heat radiation resistant screens in a bent tube shape, a liquid nitrogen screen in a bent tube shape arranged in the arc tube, and an arc shutter, a nitrogen tube and a helium tube arranged in the liquid nitrogen screen; the two nitrogen pipes are respectively arranged at the inner side and the outer side of the liquid nitrogen screen, and the blades of the arc-shaped shutter are fixed on the nitrogen pipe at the outer side; two helium pipes are arranged in the liquid nitrogen screen along the diameter direction; the pipelines of the nitrogen pipe, the helium pipe, the heat radiation shielding screen and the liquid nitrogen screen are concentric arcs; the two nitrogen pipes are communicated with each other at the end part of the arc section where the two helium pipes are located.

The inside of the liquid nitrogen screen is provided with a spring support along the diameter direction, and the two helium pipes are installed through the spring support.

The connecting line direction of the two nitrogen tube section centers is perpendicular to the connecting line direction of the two helium tube section centers.

The two nitrogen pipes are communicated with each other through a U-shaped pipe at the end part of the arc section where the two nitrogen pipes are located.

The two helium pipes are communicated with each other through a U-shaped pipe at the end part of the arc section where the two helium pipes are located.

The liquid nitrogen screen is fixed in the heat radiation protection screen through a ceramic support column.

The invention has the following remarkable effects:

by adopting the built-in high-vacuum low-temperature condensing air pump, neutral particles can be effectively and timely pumped out, and the pumping speed is high and the vibration is small. The adopted shutter design ensures that the high-temperature particles can reach the liquid helium tube after being subjected to collision pre-cooling and temperature reduction for more than one time when the high Wen Li is extracted, thereby avoiding the high-temperature particles from directly striking the liquid helium tube and reducing the heat load of the liquid helium tube; meanwhile, the shutter and the liquid nitrogen screen are compact in design structure and convenient to install in a limited space. The helium pipe becomes an independent loop in the circular arc structure of each section, so that a through circular loop is not formed in the whole device, and electromagnetic force and coupled induction heat energy formed by the circular loop under the condition of a large magnetic field of Tokamak are avoided. Meanwhile, the helium tube adopts the spring support, so that the fixing effect can be achieved, the heat conduction is small, deformation caused by temperature difference can be absorbed conveniently, and the reliability and safety of the device are improved. The built-in high-vacuum low-temperature condensing air pump has the advantages of simple integral structure, convenient installation and debugging and good processability.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a built-in high vacuum low temperature condensing pump;

FIG. 2 is a schematic diagram in detail in section;

FIG. 3 is a schematic cross-sectional view of an arcuate shutter;

FIG. 4 is a schematic diagram of a liquid nitrogen pipeline loop junction;

FIG. 5 is a schematic cross-sectional view of a liquid helium piping loop junction;

in the figure: 1. a heat radiation shield; 2. arc-shaped shutter; 3. a liquid nitrogen screen; 4. a nitrogen tube; 5. a helium tube; 6. a spring support; 7. ceramic support columns; 8.U tubes; 9. short and small U-shaped tubes.

Detailed Description

The invention is further illustrated by the following figures and detailed description.

As shown in FIG. 1, the device is composed of a plurality of sections of arc structures to form a complete circle. The preferred whole consists of four sections of 90 degree circular arc structures.

As shown in fig. 2 and 3, the internal structure of the device is described by taking a circular arc structure as an example. Each section of arc structure comprises five sections of heat radiation shielding screens 1 arranged outside, a liquid nitrogen shielding screen 3 arranged inside, and an arc shutter 2, a nitrogen pipe 4 and a helium pipe 5 which are arranged in the liquid nitrogen shielding screen 3.

The heat radiation protection screen 1 and the liquid nitrogen screen 3 are both in a bent pipe shape, and the liquid nitrogen screen 3 is arranged inside the heat radiation protection screen 1 and is fixed through the ceramic support column 7. The two nitrogen pipes 4 are respectively arranged at the inner side and the outer side of the liquid nitrogen screen 3, the arc-shaped louver 2 is fixedly arranged at the nitrogen pipe 4 at the outer side of the liquid nitrogen screen 3, and a welding mode can be adopted. Two helium pipes 5 are arranged in the diameter direction of the cross-section circle, and the helium pipes 5 are fixed by a spring support 6 arranged in the diameter direction inside the liquid nitrogen screen 3. The pipeline directions of the nitrogen pipe 4 and the helium pipe 5 and the pipeline directions of the heat radiation shielding plate 1 and the liquid nitrogen shielding plate 3 form concentric circular arcs.

The inner side and the outer side refer to the inner side and the outer side of an arc formed by installing the whole device in a tubular shape.

In a preferred embodiment, the direction of the line connecting the centers of the sections of the two nitrogen pipes 4 is perpendicular to the direction of the line connecting the centers of the sections of the two helium pipes 5.

During operation, the neutral particles are primarily cooled by the nitrogen tube 4 at the outer side through the arc-shaped louver 2, and finally condensed on the helium tube 5, so that the air extraction effect is achieved.

As shown in figure 3, the arc shutter 2 is combined with the outer nitrogen tube 4, and the high-temperature neutral particles can reach the helium tube after more than one collision energy dissipation, so that the high-temperature particles are prevented from directly striking the helium tube to cause high-heat load damage, the reliability and the safety of the device are ensured, and meanwhile, the arc shutter 2 and the liquid nitrogen screen 3 are compact in structure and are convenient to install in a limited space.

As shown in fig. 4, the two nitrogen pipes 4 at the ends of the circular arc structure are connected by a U-shaped pipe 8. As shown in fig. 5, the two helium pipes 5 at the end of the arc structure are connected through the short and small U-shaped pipe 9, so that in each arc structure, the nitrogen pipe 4 or the helium pipe 5 is self-connected, a through circular loop of the nitrogen pipe or the helium pipe is not formed in the whole built-in high-vacuum low-temperature condensation air pump, and electromagnetic force and coupled induction heat energy due to the circular loop under the condition of a magnetic field are avoided.

Claims

1. The utility model provides a built-in high vacuum low temperature condensation aspiration pump, its complete circular of by a plurality of sections circular arc structures constitution, its characterized in that: the arc structure comprises a plurality of sections of arc pipes formed by the heat radiation shielding screens (1), a bent pipe-shaped liquid nitrogen screen (3) arranged in the arc pipes, and an arc louver (2), a nitrogen pipe (4) and a helium pipe (5) arranged in the liquid nitrogen screen (3); the two nitrogen pipes (4) are respectively arranged at the inner side and the outer side of the liquid nitrogen screen (3), and the blades of the arc-shaped shutter (2) are fixed on the nitrogen pipe (4) at the outer side; two helium pipes (5) are arranged in the liquid nitrogen screen (3) along the diameter direction; the pipelines of the nitrogen tube (4), the helium tube (5), the heat radiation shielding screen (1) and the liquid nitrogen screen (3) are concentric arcs; the two nitrogen pipes (4) are communicated at the end parts of the arc sections, and the two helium pipes (5) are communicated at the end parts of the arc sections.

2. The in-line high vacuum low temperature condensing pump of claim 1, wherein: the inside of the liquid nitrogen screen (3) is provided with a spring support (6) along the diameter direction, and the two helium pipes (5) are installed through the spring support (6).

3. The in-line high vacuum low temperature condensing pump of claim 1, wherein: the connecting line direction of the cross section centers of the two nitrogen pipes (4) is perpendicular to the connecting line direction of the cross section centers of the two helium pipes (5).

4. The in-line high vacuum low temperature condensing pump of claim 1, wherein: the two nitrogen pipes (4) are communicated with each other through a U-shaped pipe at the end part of the arc section where the two nitrogen pipes are located.

5. The in-line high vacuum low temperature condensing pump of claim 1, wherein: the two helium pipes (5) are communicated with each other through a U-shaped pipe at the end part of the arc section where the helium pipes are located.

6. The in-line high vacuum low temperature condensing pump according to any one of claims 1-5, characterized in that: the liquid nitrogen screen (3) is fixed in the heat radiation protection screen (1) through a ceramic support column (7).