Gas breakdown in an atmospheric pressure radio-frequency capacitive plasmasource

Gas breakdown is studied in an atmospheric pressure rf capacitive plasma so urce developed for materials applications. At a rf frequency of 13.56 MHz, breakdown voltage is largely a function of the product of the pressure and the discharge gap spacing, approximating the Paschen curve. However, breakd own voltage varies substantially with rf frequency due to a change in the e lectron loss mechanism. A large increase in breakdown voltage is observed w hen argon, oxygen, or nitrogen is added to helium despite their lower ioniz ation potential. Discussion is given for optimal breakdown conditions at at mospheric pressure. (C) 2001 American Institute of Physics.