Simultaneous measurement of viscosity and flow velocity in Texas Experimental Tokamak-Upgrade (TEXT-U) edge plasmas by using a Visco-Mach probe

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.872424· OSTI ID:565368

Chung, K; Bengtson, R D ^[1]

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1. Fusion Research Center Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

Shear viscosity [{eta}{equivalent_to}{alpha}{times}(massdensity){times}(diffusivity)] and parallel flow velocity [M{sub {infinity}}{times}{radical}((T{sub e}+T{sub i})/m{sub i})] of tokamak edge plasma were simultaneously measured in the Texas Experimental Tokamak-Upgrade (TEXT-U) tokamak by using a {open_quotes}Visco-Mach{close_quotes} probe with the iteration method (VMPI) [K-S. Chung, Nucl. Fusion {bold 34}, 1213 (1994)]. The VMPI was composed of two Mach probes measuring two ratios of ion saturation current densities, with the small Mach probe located within the free presheath generated by the large Mach probe (LMP). Radial variations of the normalized shear viscosity, {alpha}, and parallel Mach number, M{sub {infinity}}, for typical discharges were deduced from two measured ratios of ion saturation current densities, and plasma density from ion saturation currents by LMP. Here {alpha} varied from 0.7 to 1.3 with an estimated error of {plus_minus}40{percent}, and M{sub {infinity}} from 0 to 0.2 for 0{lt}r{minus}r{sub l}{lt}4.5cm, where r{sub l}=27cm is the limiter radius. Also, {alpha} and M{sub {infinity}} increased with the radial direction, while cross-field diffusivity (D{sub {perpendicular}}) was approximately constant. Here D{sub {perpendicular}} is obtained as {approximately}3D{sub B}, where a typical Bohm diffusivity (D{sub B}) is {approximately}1m{sup 2}/s. {copyright} {ital 1997 American Institute of Physics.}

• DOE Contract Number: FG03-94ER54241
• OSTI ID: 565368
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 4; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CURRENT DENSITY
DIFFUSION
FLOW RATE
ITERATIVE METHODS
PLASMA DIAGNOSTICS
PLASMA SHEATH
TEXT DEVICES
TOKAMAK DEVICES
VELOCITY
VISCOSITY