Thread groove type vacuum pump

摘要

A thread groove type vacuum pump in which the gap between a rotor and a stator is not subjected to any influence of the rotor temperature and thus the pumping performance does not deteriorate during plasma combustion in a nuclear fusion reactor. The thread groove pumping portion is formed as a circular cone so that the expansion and contraction of the rotor occurs along the generatrix of the circular cone. The pump exhibits supreme pumping performance throughout the whole running mode of the vacuum pumping system of the nuclear fusion reactor because the gap between the rotor and the stator is kept constant despite changes of thermal expansion due to the temperature change of the rotor caused by the different gas loads.