Development Of Liquid Helium Cryocondensation Pump For Drift Tube Of Neutral Beam Injection System

Neutral Beam Injection (NBI) heating having become one of the main auxiliary heating methods in large experimental nuclear fusion research devices for its simple heating principle, mature technology theory and high injection power. The working principle of NBI and the important function of the drift tube are introduced in details, A Liquid helium cryocondensation pump with a capacity of 20,000L/s is designed for the drift tube based on the analysis on 3 kinds of pumping mechanisms.In this paper it is thoroughly discussed that the selection of the shape and the material of the cryocondensation chamber, design calculation and techniques, heat load distribution of the cryogenic system, liquid level measuring system, temperature and vacuum measuring system, temperature distribution of the Chevron baffles and the liquid helium condensation plate and gas distribution in drift-tube. By processing and analyzing the experimental data during cooling down, many key performance data of cryocondensation pump have been gained.The developed Liquid Helium Cryocondensation pump for drift tube of Neutral Beam Injection system is proves to be efficient for the quick pumping of the hydrogen from the vacuum chamber and transferring of the beam. In addition, abundant engineer and physics data have been accumulated for the research of high pumping speed cryocondensation in the future.