A comparison of Langmuir probe techniques for measuring temperature fluctuations

Abstract

Two techniques are applied and the results compared in the edge plasma of TEXT-U to estimate temperature fluctuations. The first technique fits the measured current fluctuations from a double probe as a function of probe bias with several fitting functions to provide density, and temperature fluctuations but with no spectral information. The second method uses a triple-probe technique to measure density, temperature, and floating potential as a function of time. The two techniques are in agreement to within estimated error limits and find T̃/T≊0.4–0.5 ñ/n both in the scrape-off layer and in the main body of the plasma.