Study of an RF mercury discharge: Effect of metastable atoms

A planar one-dimensional particle-in-cell simulation with Monte Carlo Collisions (XPDP1) has been used to study 13.56 MHz mercury discharge including metastable species. Reactions such as metastable creation, ionization from the metastable state, collisions between two metastables were taken into account. The effect of pressure and applied voltage on the metastable density was examined. At high pressure and high voltage the metastable profile is strongly peaked at the sheath edges. At low pressure and low voltage the density profiles are rather hat at the bulk plasma. The shape of the profile is determined by mean free path for electrons and metastables in the discharge.