Electron heating in low-pressure rf glow discharges

Particle-in-cell simulations of radio frequency glow discharges between parallel-plate electrodes were performed to test the role of secondary emission at applied frequencies above the ion plasma frequency. With the secondary electron emission coefficient set to zero, the high-energy tail of the electron energy distribution function in the center of the glow is modulated at the applied frequency, and these energetic electrons show substantial anisotropy. In addition, a pulse of ionization propagates across the glow, correpsonding to the directed velocity of the high-energy electrons in the center of the glow. These high-energy electrons originate at the plasma-sheath boundary and appear to be the result of sheath heating.