Measurement of virtual cathode structures in a plasma sheath caused by secondary electrons

The measured potential profiles of unmagnetized plasma sheath near a stainless steel plate exhibit deep virtual cathode structures caused by secondary electrons produced by high-speed ions hitting the surface of the plate. The depth and thickness of the virtual cathode depend on the ion streaming energy and gas pressure. The experimental results are in agreement with numerical calculations. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3695395]