Inflow angular dependency on cryopump and beam target in hall thruster test facility

A role of a beam target installed in ground tests facilities for electric propulsion devices were investigated in terms of induced flow to cryopumps. Cryopumps are widely used for producing high vacuum environments in electric propulsion ground test facilities and their pumping speed depend on an angle where particle flow comes from due to their structure. Particle trajectory from a beam target inside a vacuum chamber for electric propulsion test was calculated by direct simulation Monte Carlo method in a three-dimensional simulation model. Inflow angle of particle flow to pumps varies with a cone angle of a conical beam target, and the peak of inflow angular distribution is 45 degrees on the pump installed at the position where the flux density from the target takes a peak. This result shows that the optimization of the pumping speed of cryopumps is able to be achieved by designing locations of cryopumps with respect to the flux distribution from a beam target..