Neutrals beam injection （NBI） has proven to be a very effective method for plasma heating. A set of positive-ion-based NBI system is being designed, manufactured and tested at ASIPP. The aim of this study was to asc...Neutrals beam injection （NBI） has proven to be a very effective method for plasma heating. A set of positive-ion-based NBI system is being designed, manufactured and tested at ASIPP. The aim of this study was to ascertain the most effective cryocondensation pump structure for the hydrogen NBI system. The parameter design and mechanical design were made to determine the optimum parameters and structure of the cryocondensation pump. The lowest pressure of 7.2 × 10^-6 Pa was achieved in the vacuum chamber, which indicated that this type of liquid helium cryocondensation pump could meet the requirement of the NBI system quite well.展开更多
To decrease the radiation heat load of the cryopanel is considered to be necessary for the design of cryopumps. In general, a radiation baffle is mounted between the cryopanel and the heat source. The radiation baffle...To decrease the radiation heat load of the cryopanel is considered to be necessary for the design of cryopumps. In general, a radiation baffle is mounted between the cryopanel and the heat source. The radiation baffle absorbs the majority of the radiated heat load. However, the motion of molecules to be pumped is baffled and the pumping speed is lowered at the same time. Therefore the selection of a good radiation baffle is a very important issue for the economical operation of the cryopump. By calculating and comprehensively analyzing the thermal transmission coefficients and the molecular transmission coefficients of baffles of different structures, a type of Chevron baffle is found to be more satisfactory. This paper focuses on the application of the Monte Carlo Method involved in the process of analysis and calculation.展开更多
The lower cryopump ports in International Thermonuclear Experimental Reactor （ITER） as a part of the vacuum vessel play many important roles. As the boundary of vacuum it must be ensured against structural damage. I...The lower cryopump ports in International Thermonuclear Experimental Reactor （ITER） as a part of the vacuum vessel play many important roles. As the boundary of vacuum it must be ensured against structural damage. In this study a finite element model of the lower cryopump ports was developed by ANSYS code with a purpose to evaluate the stress and displacement level on it. Two kinds of loads were taken into account. One was the hydrostatic pressure including the normal operation pressure and test pressure. The other was the seismic load. The analysis results show that the peak stress does not exceed the allowable stress for either the hydrostatic pressure or the seismic load according to the ITER structural design criterion, which indicates that the structure has a good safety margin.展开更多
The xenon pumping speed testing system of the large-diameter external cryopump was designed to meet the plume test requirements for prototype electric propulsion.The flowmeter method was utilized to measure the xenon ...The xenon pumping speed testing system of the large-diameter external cryopump was designed to meet the plume test requirements for prototype electric propulsion.The flowmeter method was utilized to measure the xenon pumping speed.The test results show that the averaged effective pumping speed of doublecryopumps is 52 200L/s,and that of single-cryopump is 27 100L/s.The pumping speed ratio of two configurations is 1.93.It can be concluded that the pumping speed has in linear relationship with the number of cryopump,and the coefficient is irrelevant with the gas type.The averaged effective pumping speed of xenon is less than its nominal pumping speed,and the averaged pumping efficiency is 0.83.Under the identical inflow conditions,the averaged effective pumping speed ratio of nitrogen is 0.53,slightly less than the theoretical pumping speed ratio of 0.55.Consequently,it can be concluded that results assessment of large-diameter external cryopump design index can guide the engineering application,showing certain reference significance.展开更多
文摘Neutrals beam injection （NBI） has proven to be a very effective method for plasma heating. A set of positive-ion-based NBI system is being designed, manufactured and tested at ASIPP. The aim of this study was to ascertain the most effective cryocondensation pump structure for the hydrogen NBI system. The parameter design and mechanical design were made to determine the optimum parameters and structure of the cryocondensation pump. The lowest pressure of 7.2 × 10^-6 Pa was achieved in the vacuum chamber, which indicated that this type of liquid helium cryocondensation pump could meet the requirement of the NBI system quite well.
文摘To decrease the radiation heat load of the cryopanel is considered to be necessary for the design of cryopumps. In general, a radiation baffle is mounted between the cryopanel and the heat source. The radiation baffle absorbs the majority of the radiated heat load. However, the motion of molecules to be pumped is baffled and the pumping speed is lowered at the same time. Therefore the selection of a good radiation baffle is a very important issue for the economical operation of the cryopump. By calculating and comprehensively analyzing the thermal transmission coefficients and the molecular transmission coefficients of baffles of different structures, a type of Chevron baffle is found to be more satisfactory. This paper focuses on the application of the Monte Carlo Method involved in the process of analysis and calculation.
基金National 973 programme of the Ministry of Science and Technology of China(No.2004CB720704)
文摘The lower cryopump ports in International Thermonuclear Experimental Reactor （ITER） as a part of the vacuum vessel play many important roles. As the boundary of vacuum it must be ensured against structural damage. In this study a finite element model of the lower cryopump ports was developed by ANSYS code with a purpose to evaluate the stress and displacement level on it. Two kinds of loads were taken into account. One was the hydrostatic pressure including the normal operation pressure and test pressure. The other was the seismic load. The analysis results show that the peak stress does not exceed the allowable stress for either the hydrostatic pressure or the seismic load according to the ITER structural design criterion, which indicates that the structure has a good safety margin.
基金National Defense Science and Industry Bureau the Sino Russian in Cooperation of Spaceflight
文摘The xenon pumping speed testing system of the large-diameter external cryopump was designed to meet the plume test requirements for prototype electric propulsion.The flowmeter method was utilized to measure the xenon pumping speed.The test results show that the averaged effective pumping speed of doublecryopumps is 52 200L/s,and that of single-cryopump is 27 100L/s.The pumping speed ratio of two configurations is 1.93.It can be concluded that the pumping speed has in linear relationship with the number of cryopump,and the coefficient is irrelevant with the gas type.The averaged effective pumping speed of xenon is less than its nominal pumping speed,and the averaged pumping efficiency is 0.83.Under the identical inflow conditions,the averaged effective pumping speed ratio of nitrogen is 0.53,slightly less than the theoretical pumping speed ratio of 0.55.Consequently,it can be concluded that results assessment of large-diameter external cryopump design index can guide the engineering application,showing certain reference significance.
