Analysis of particle penetration length into the wall crevices

The present work investigates the effects of the surface roughness on the plasma-wall interactions via kinetic simulations of an initial value problem using the particle-in-cell code VPIC[K. J. Bowers et al., Phys. Plasmas 15, 055703 (2008)]. Collisionless plasma immersed in parallel to the wall magnetic field is self-consistently interacting with a nonflat surface, whose roughness is varied relative to the thermal ion gyroradius. The analysis of the numerical results and analytical estimates yields a scaling of the penetration length that can be described by an analytical formula.