Energy influx measurements with an active thermal probe in plasma-technological processes
Institut für Experimentelle und Angewandte Physik, Leibnizstr. 19, Kiel, D-24098, Germany
2 Formerly Institut für Plasmaforschung und Technologie, Felix-Hausdorff-Str. 2, Greifswald, D-17489, Germany
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Accepted: 4 February 2015
Published online: 24 February 2015
Many plasma-technological applications are based on plasma wall interaction, which can be characterised by calorimetric probes to measure the energy influx from the plasma to the substrate surface. Passive probes are based on the principle of recording the temperature course during heating and cooling of the probe for calculating the energy influx. The disadvantages of these probes are that the energy influx has to be interrupted by switching off the energy source or by using suitable apertures and by the necessity of knowing the exact heat capacity of the probe.
A continuously operating active probe is, therefore, developed which does not need to be calibrated and which compensates the environmental effects as well as the heat conduction by the probe holder. By means of controlled electrical heating the probe is set to a given working temperature and then the energy supply supporting the fixed operating temperature is measured. The energy influx by the plasma is compensated by decreasing the heating power and is directly displayed in J/cm2s. Some practical measurements are presented. Even, if the probe is designed as double probe the directionality of the energy influx can be determined.
Key words: Sensors / Thermal probe / Energy influx / Process control
© The Author(s), 2015