The plasma parameters and relative positive and negative ion concentrations in a small, filtered, multicusp ion source, operating at low plasma density (<1*1011 cm-3) with both hydrogen and deuterium gas have been measured using a Langmuir probe and a small mass spectrometer. Under identical source operating conditions the plasma density in D2 is found always to be higher than in H2, while the negative ion density is found to be consistently lower in D2 then in H2. The effect of the different isotopes on transport processes in the discharge can be understood in terms of a simple model. The isotope effect on molecular processes is also discussed.

Comparisons between experimentally measured time-dependent electron energy distribution functions and optical emission intensities are reported for low-frequency (100 and 400 kHz) radio-frequency driven discharges in argon. The electron energy distribution functions were measured with a time-resolved Langmuir probe system. Time-resolved optical emissions of argon resonance lines at 687.1 and 750.4 nm were determined by photon-counting methods. Known ground-state and metastable-state excitation cross sections were used along with the measured electron energy distribution functions to calculate the time dependence of the optical emission intensity. It was found that a calculation using only the ground-state cross sections gave the best agreement with the time dependence of the measured optical emission. Time-dependent electron density, electron temperature, and plasma potential measurements are also reported.

The basic plasma parameters of a tandem multicusp ion source operating with hydrogen and deuterium gas have been measured and are compared. It is found that there is little variation in the electron temperature or electron energy-distribution function; however, both the electron density and plasma potential are consistently higher when operating with D2 rather than H2 gas. The experimental results are in general agreement with simple models of the discharge.

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