Biasing, Acquisition and Interpretation of a Dense Langmuir Probe Array in NSTX
Authors: M. A. Jaworski, J. Kallman, R. Kaita, H. Kugel, B. LeBlanc, and R. Marsala and D. Ruzic
Abstract:
A dense array of 99 Langmuir probes has been installed in the lower divertor region of the National Spherical Torus Experiments (NSTX). This array is instrumented with a system of elec- tronics that allows flexibility in the choice of probes to bias as well as the type of measurement (including standard swept, single probe, triple probe and operation as passive floating potential and scrape-off-layer (SOL) current monitors). The use of flush-mounted probes requires careful inter- pretation. The time dependent nature of the SOL makes swept-probe traces difficult to interpret. To overcome these challenges, the single- and triple-Langmuir probe signals are used in comple- mentary fashion to determine the temperature and density at the probe location. A comparison to mid-plane measurements is made. Work is supported by DOE contracts DE-AC02-09CHI1466 and DE-PS02-07ER07-29.
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Submitted to: Review of Scientific Instruments (May 2010)
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Download PPPL-4552 (pdf 246 KB 8 pp)
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