Microwave and mass spectrometric studies of afterglow processes in plasmas produced in rare gases

An experimental system comprising a conventional X-band cavity arrangement in conjunction with a quadrupole mass spectrometer has been developed to allow simultaneous measurement of the time-dependent number densities of electrons and positive ions in decaying rare gas plasmas. In argon, ions at m/e=20, 40 and 80 amu, identified as Ar 2+ , Ar + and Ar 2 + respectively were detected and measurement of the decay time constants yielded reduced mobilities of Ar + and Ar 2 + . The lifetime of the ion identified as Ar 2+ was too short to allow accurate time resolved measurements to be carried out. In krypton, ions identified as Kr 2+ , Kr + and Kr 2 + were detected and reduced mobility values for the two singly charged ions deduced. Experiments in xenon were limited by the mass range capabilities of the mass spectrometer, but gave reduced mobilities for the singly charged atomic and molecular ions.