Low energy neutral spectroscopy during pulsed discharge cleaning in PLT

The efflux of neutral hydrogen from PLT during discharge cleaning has been measured using a time‐of‐flight spectrometer. During high ionization pulsed discharge cleaning (PDC), the flux in the energy range of 5 to 1000 eV varies from 1014 H0/cm2⋅s to 1016 H0/cm2⋅s and the average energy from 10 to 80 eV. The energy distributions are nearly single temperature Maxwellians. Low ionization PDC (Taylor‐type) produces a 1000 times lower fluence in the same energy range; however, a flux of 1016 H°/cm2⋅s at energies less than 5 eV is inferred. The detailed submillisecond time variation of these parameters with the fill gas pressure and state of cleanliness of the machine is presented. Comparisons with UV spectroscopy, bolometric measurements, and residual gas analysis are made.