High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions

Kallman, J.; Jaworski, M. A.; Kaita, R.; Kugel, H.; Gray, T. K.
October 2010
Review of Scientific Instruments;Oct2010, Vol. 81 Issue 10, p10E117
Academic Journal
A high density Langmuir probe array has been developed for measurements of scrape-off layer parameters in NSTX. Relevant scale lengths for heat and particle fluxes are 1-5 cm. Transient edge plasma events can occur on a time scale of several milliseconds, and the duration of a typical plasma discharge is ∼1 s. The array consists of 99 individual electrodes arranged in three parallel radial rows to allow both swept and triple-probe operation and is mounted in a carbon tile located in the lower outer divertor of NSTX between two segments of the newly installed liquid lithium divertor. Initial swept probe results tracking the outer strike point through probe flux measurements are presented.


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