Berlin 2014 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 13: Poster Session - Diagnostics
P 13.2: Poster
Dienstag, 18. März 2014, 16:30–18:30, SPA Foyer
Cleaning surface contamination of Langmuir probes with Ultraviolet light — •Christian T. Steigies1 and Aroh Barjatya2 — 1Christian-Albrechts-Universität zu Kiel, Germany — 2Embry-Riddle Aeronautical University, FL, USA
The Langmuir probe is a standard instrument for in-situ measurements of the plasma density and temperature, as well as an indicator of spacecraft charging. It is well known that the probe characteristics are distorted by surface contamination effects leading to erroneous measurements of plasma parameters. This not only affects swept Langmuir probes, where this problem is clearly visible in the data with a properly chosen sweep function, but it also modifies the spectrum of fixed-bias probes, where the contamination is not immediately seen in the data. Several approaches to remove the water layer, which causes the contamination, have been undertaken. These include removing the contamination by ion bombardment and internal heating, as well as sweeping at higher rates to bypass the contamination. One method that is frequently used in vacuum systems, and has never been used on a sounding rocket, is using ultra-violet (UV) light to desorb the water layer from the surface. UV light has sufficient energy to also desorb water layers with stronger bonds, and not just the outermost layer that is easily removed via heating. We present here a concept that uses UV light to clear surface contamination on Langmuir probes in sounding rockets.