Hibp Measurements Using Simultaneous Detection of Ion Species.

A Heavy Ion Beam Probe system was implemented on a small tokamak, RENTOR, using two separate Electrostatic Energy Analyzers. This allowed two successively higher charger states of a singly charged Cesium probing beam to be simultaneously detected from closely overlapping regions of the magnetically confined plasma. The measured ratios of these ion species were a sensitive monitor of the average energy of the plasma electrons. The measured ratios of ion species were anomalously low, precluding an accurate determination of the electron temperature based on a Maxwellian velocity distribution. However, the beam probe technique developed in this thesis can be used as a relative measurement of T_{ rm e}, using a scaling term for consistency with other temperature diagnostics. The time and space resolved data provided by this technique allows the heat flux due to conduction from the plasma to be evaluated. Calculations indicate that the power losses due to thermal conductivity are approximately 10% of the total input power which is reasonable for the type of plasmas under investigation, where the dominant energy loss mechanism is radiation. The plasma discharges investigated in RENTOR were most likely non-thermal and the multiple ion species technique can be shown to be sensitive to deviations from a Maxwellian plasma. Using a displaced Maxwellian model, reasonable agreement is obtained, suggesting that the plasma discharges investigated in RENTOR had mildly runaway or slideaway electrons. Inferred toroidal drift velocities were on the order of a few keV. Additionally, the system was capable or providing independent, simultaneous space potential measurements from the Cs^{2+} and Cs ^{3+} ions. Both ion species yield reasonably close estimates of the space potential, with central values in the neighborhood of 400 Volts.