Flow measurements in the edge plasma of TEXT

Technical Report · Wed May 01 04:00:00 EDT 1996

OSTI ID:285452

Back, R

A new Langmuir probe array, capable of measuring flow velocities along with other plasma parameters was built and tested at the Texas Experimental Tokamak. The circular probe head features 16 carbon pins and was made from boron nitride to allow a large penetration depth of the edge plasma. Four {open_quotes}proud{close_quotes} pins were used to measure the usual plasma parameters and their fluctuations, such as temperature and density. They were surrounded by 12 partially shielded pins mounted on the circumference which allowed the determination of parallel flow velocity. Experimental data demonstrating the capabilities are presented, in particular profiles of the parallel and perpendicular flow velocity. Limits in the accuracy of the models used with special emphasis on turbulent viscosity are discussed. Observed shear flow caused by a significant change in the connection length from the probe to the nearest wall has been observed and is used to deduce a value for the perpendicular viscosity. Comparisons with the perpendicular diffusion coefficient support the theoretical assumption of {eta} {approx_equal} D{sub {perpendicular}}. The results also suggest that a similar probe array might be used for diagnosis of the edge velocity shear layer which is thought to be of importance in H-mode formation.

• Research Organization: Texas Univ., Austin, TX (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG03-94ER54241
• OSTI ID: 285452
• Report Number(s): DOE/ER/54241--162
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DENSITY
FLOW MODELS
LANGMUIR PROBE
PLASMA SCRAPE-OFF LAYER
TEMPERATURE MEASUREMENT
TEXT DEVICES
VISCOUS FLOW