Experimental study of the ionization front in pulsed-surface-wave-produced plasmas

The advance of the ionization front along the plasma column is studied during the formation process of plasmas produced by a surface wave. The experimental measurements have been performed in argon gas, for the 0.1-30-Torr pressure range, using pulsed microwave power at 2.45 GHz. The ionization front velocity decreases along the plasma column, from its maximum value at the launcher to the zero value at the stationary plasma column end, similarly to the surface-wave power diminution. This velocity can be expressed to depend only on the product collision frequency times tube radius and the surface-wave incident power along the plasma column.