  Particle-in-cell/Monte Carlo technique is used to simulate low pressure
electro-negative and electro-positive plasmas at a frequency of 10 MHz. The
potential, electric field, electron and ion density, and currents flowing
across the plasma are presented. To compare the physical properties of the
electro-positive gas with those of an electro-negative gas, the input voltage
was decreased from 1000 Volts to 350 Volts. The simulation results indicate
that the introduction of negative ions induces dramatic effects on the spatial
and temporal variation of the electric field and on the behavior of the
electron, ion, and displacement currents. In particular, the numerical modeling
predicts the formation of double-layer at the plasma-sheath boundary of
electro-negative discharge.
