Modulation of Electron Velocity Distribution Function by Moving Cathode Sheath in a Low-Pressure rf Discharge

Abstract

Interaction between a moving collisionless cathode sheath and bulk electrons in a completely asymmetrical rf glow discharge is studied numerically. The incident electron velocity distribution function, assumed to be Maxwellian, is found to be modulated markedly by the interaction with the rf sheath expanding and contracting symmetrically in time. An electron beam toward the bulk plasma with sufficiently high velocity for ionization of atoms is generated during the sheath expansion. The modulated distribution function and the beam velocity are almost independent of the voltage applied on the cathode, although a slight extension of the tail and a slight increase in the beam velocity are observed with increases in voltage.