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Title: Overestimation of Mach number due to probe shadow

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 7; Related Information: CHORUS Timestamp: 2016-12-27 20:23:14; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

Citation Formats

Gosselin, J. J., Thakur, S. C., Sears, S. H., McKee, J. S., Scime, E. E., and Tynan, G. R. Overestimation of Mach number due to probe shadow. United States: N. p., 2016. Web. doi:10.1063/1.4954820.
Gosselin, J. J., Thakur, S. C., Sears, S. H., McKee, J. S., Scime, E. E., & Tynan, G. R. Overestimation of Mach number due to probe shadow. United States. doi:10.1063/1.4954820.
Gosselin, J. J., Thakur, S. C., Sears, S. H., McKee, J. S., Scime, E. E., and Tynan, G. R. 2016. "Overestimation of Mach number due to probe shadow". United States. doi:10.1063/1.4954820.
title = {Overestimation of Mach number due to probe shadow},
author = {Gosselin, J. J. and Thakur, S. C. and Sears, S. H. and McKee, J. S. and Scime, E. E. and Tynan, G. R.},
abstractNote = {},
doi = {10.1063/1.4954820},
journal = {Physics of Plasmas},
number = 7,
volume = 23,
place = {United States},
year = 2016,
month = 7

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4954820

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Cited by: 2works
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  • Comparisons of the plasma ion flow speed measurements from Mach probes and laser induced fluorescence were performed in the Controlled Shear Decorrelation Experiment. We show the presence of the probe causes a low density geometric shadow downstream of the probe that affects the current density collected by the probe in collisional plasmas if the ion-neutral mean free path is shorter than the probe shadow length, L{sub g} = w{sup 2} V{sub drift}/D{sub ⊥}, resulting in erroneous Mach numbers. We then present a simple correction term that provides the corrected Mach number from probe data when the sound speed, ion-neutral mean free path,more » and perpendicular diffusion coefficient of the plasma are known. The probe shadow effect must be taken into account whenever the ion-neutral mean free path is on the order of the probe shadow length in linear devices and the open-field line region of fusion devices.« less
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  • We have installed and operated a reciprocating Langmuir/Mach probe to simultaneously measure parallel and perpendicular plasma flow profiles along with density, temperature, floating potential profiles, and fluctuating parameters such as fluctuation driven particle flux and wave number on a single shot. Plasma facing components are made from boron nitride and the probe tips are 1-mm-diam carbon cylinders. The Mach probe, designed following the Gundestrup model, has 12 probes arranged in a circular array. Four Langmuir probes mounted at the front of the Mach probe array measure floating potential, ion saturation current, and temperature. The perpendicular flow velocity measurements reduced frommore » the Mach probe array compare well with the phase velocity measured from the proud Langmuir probes and the E{sub r}{times}B poloidal rotation. {copyright} {ital 1997 American Institute of Physics.}« less