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Title: Functional form for plasma velocity in a rapidly rotating tokamak discharge

Abstract

A recently developed technique using charge exchange spectroscopy determines the ion poloidal rotation in tokamak plasmas from the poloidal variation in the toroidal angular rotation speed. The basis for this technique is the functional form for the plasma velocity calculated from the equilibrium equations. The initial development of this technique utilized the functional form determined for conditions where the ion toroidal rotation speed is much smaller than the ion thermal speed. There are cases, however, where the toroidal rotation can be comparable to the ion thermal speed, especially for high atomic number impurities. The present paper extends the previous analysis to this high rotation speed case and demonstrates how to extract the poloidal rotation speed from measurements of the toroidal angular rotation speed at two points on a flux surface.

Authors:
 [1];  [2]
  1. General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)
  2. University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States)
Publication Date:
OSTI Identifier:
22299822
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CHARGE EXCHANGE; MAGNETIC SURFACES; PLASMA; PLASMA IMPURITIES; SPECTROSCOPY; TOKAMAK DEVICES; VELOCITY

Citation Formats

Burrell, K. H., and Chrystal, C. Functional form for plasma velocity in a rapidly rotating tokamak discharge. United States: N. p., 2014. Web. doi:10.1063/1.4891351.
Burrell, K. H., & Chrystal, C. Functional form for plasma velocity in a rapidly rotating tokamak discharge. United States. doi:10.1063/1.4891351.
Burrell, K. H., and Chrystal, C. Tue . "Functional form for plasma velocity in a rapidly rotating tokamak discharge". United States. doi:10.1063/1.4891351.
@article{osti_22299822,
title = {Functional form for plasma velocity in a rapidly rotating tokamak discharge},
author = {Burrell, K. H. and Chrystal, C.},
abstractNote = {A recently developed technique using charge exchange spectroscopy determines the ion poloidal rotation in tokamak plasmas from the poloidal variation in the toroidal angular rotation speed. The basis for this technique is the functional form for the plasma velocity calculated from the equilibrium equations. The initial development of this technique utilized the functional form determined for conditions where the ion toroidal rotation speed is much smaller than the ion thermal speed. There are cases, however, where the toroidal rotation can be comparable to the ion thermal speed, especially for high atomic number impurities. The present paper extends the previous analysis to this high rotation speed case and demonstrates how to extract the poloidal rotation speed from measurements of the toroidal angular rotation speed at two points on a flux surface.},
doi = {10.1063/1.4891351},
journal = {Physics of Plasmas},
number = 7,
volume = 21,
place = {United States},
year = {Tue Jul 15 00:00:00 EDT 2014},
month = {Tue Jul 15 00:00:00 EDT 2014}
}
  • A recently developed technique using charge exchange spectroscopy determines the ion poloidal rotation in tokamak plasmas from the poloidal variation in the toroidal angular rotation speed. The basis for this technique is the functional form for the plasma velocity calculated from the equilibrium equations. The initial development of this technique utilized the functional form determined for conditions where the ion toroidal rotation speed is much smaller than the ion thermal speed. There are cases, however, where the toroidal rotation can be comparable to the ion thermal speed, especially for high atomic number impurities. Furthermore, the present paper extends the previousmore » analysis to this high rotation speed case and demonstrates how to extract the poloidal rotation speed from measurements of the toroidal angular rotation speed at two points on a flux surface.« less
  • A method previously described by Butterworth and Ipser for constructing models of rapidly rotating fluid bodies in general relativity is modified to enable construction of solutions whose sources are very highly flattened. In particular, solutions with increasing oblateness and decreasing angular velocity are exhibited. Also, a discussion is given of the possible association of the terminal of relativistic sequences by equatorial shedding and the first secular axisymmetric instability of the Maclaurin spheroids.
  • Experiments on the axial breathing mode in a rapidly rotating Bose-Einstein condensate are examined. Assuming a cold cloud without thermal component, we show that errors due to defocus of an imaging camera in addition to an inclination of the rotational axis can lead to a significant underestimate of the rotation rate in the fast rotation limit; within these uncertainties, our theoretical prediction agrees with the experimental data. We also show that, in the fast rotation regime, the Thomas-Fermi theory, which is inapplicable there, underestimates the rotation rate. Underestimation of the rotation rate due to these effects would also partly explainmore » a discrepancy between theory and experiment for the Tkachenko mode frequency in the fast rotation regime.« less
  • Zonal flows, initially driven by ion-temperature-gradient turbulence, may evolve due to the neoclassic polarization in a collisionless tokamak plasma. In our previous work [D. Zhou, Nucl. Fusion 54, 042002 (2014)], the residual zonal flow in a tokamak plasma rotating toroidally at sonic speed is found to have the same form as that of a static plasma. In the present work, the form of the residual zonal flow is presented for tokamak plasmas rotating toroidally at arbitrary velocity. The gyro-kinetic equation is analytically solved for low speed rotation to give the expression of residual zonal flows, and the expression is thenmore » generalized for cases with arbitrary rotating velocity through interpolation. The zonal flow level decreases as the rotating velocity increases. The numerical evaluation is in good agreement with the former simulation result for high aspect ratio tokamaks.« less