Calculation of cathode heating in analytical glow discharges

The temperature of the cathode (sample) in analytical glow discharges is calculated as a function of depth in the sample, by means of a one-dimensional heat conduction equation. The energy input is determined by the energetic ions and atoms bombarding the cathode. Calculations are performed for a Cu sample, under various conditions, ranging from perfect cooling from the backside, to the limit of no cooling. The effect of the discharge conditions (voltage-pressure-current) is also investigated. Finally, simulations are carried out for various cathode materials. It is found that the efficiency of cooling has a very important effect on the cathode surface temperature. Moreover, different cathode materials can give rise to great differences in the cathode surface temperature for the same power input, due to a different thermal conductivity.