Abstract Details

mauel_icc06_poster.pdf2006-02-20 06:53:06M. Mauel

Reconstruction of the Pressure Profile of LDX High Beta Plasma

Author: M. E. Mauel
Submitted: 2005-12-21 15:28:54

Co-authors: I. Karim, A. Boxer, J. Ellsworth, D. Garnier, A. Hansen, J. Kesner, and E. Ortiz

Contact Info:
Columbia University
500 West 120th Street
New York, NY   10027
United States

Abstract Text:
Basic considerations for modeling and measuring anisotropic
pressure equilibria in LDX are discussed. We compute a
least-squares best-fit of a pressure model, introduced
previously by Connor-Hastie, to magnetic and x-ray measurements.
The anisotropic pressure has four parameters: (1) the ratio
P(perp)/P(para), (2) the radial location of the peak pressure,
(3) the radial width of the pressure profile, and (4) the plasma
diamagnetic current. To fit this model to the magnetic
measurements, the plasma current is related to the pressure
through the self-consistent equilibrium. Since the detected
signal from a magnetic sensor combines contributions from the
plasma current with the decrease of the current required to
maintain constant the flux linked by the superconducting dipole,
we find equally good fits occur either with steep profiles
centered at large radii or with broad profiles centered at
smaller radii. These equilibrium profiles have similar plasma
dipole moments. When only single-frequency ECRH is applied,
very good fits result for a range of pressure-peak profiles that
is resolved using x-ray imaging. Plasma with the highest values
of beta and diamagnetic current are created with
multiple-frequency heating. The sum of the mean-square
deviations between the best-fit model profile and the magnetic
measurements doubles as compared with single-frequency heating,
and this may be related to the presence of two pressure peaks,
one at each resonance. With the pressure profile peak assumed to
be midway between the resonances, then 5 kW of heating creates a
plasma with 3.5 kA of plasma current, a peak perpendicular
pressure of 750 Pa, and a maximum local beta of 21%. This poster
will present details of the reconstruction procedure and
describe new magnetic sensors that will achieve improved
reconstruction accuracy.

Characterization: A2

Please place with other LDX posters

The University of Texas at Austin

Innovative Confinement Concepts Workshop
February 13-16, 2006
Austin, Texas

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