Test Particle Monte Carlo Simulation of Return Flux due to Ambient Scatter of Outgassing Molecules

The return flux on circular disk surface due to ambient scatter of outgassing molecules is simulated by using the test particle Monte Carlo (TPMC) method. The return flux ratio (RFR) obtained here for the return flux problem is in good agreement with existent results. Moreover, some factors affecting the return flux, such as the radius and temperature of the circular disk and the freestream molecular mass, velocity, temperature and molecular number density, have been analyzed and the mechanism how they affect RFR. has been discussed, which provide theoretical explanations for the evaluation and control of the return flux contamination.