Bulletin of the American Physical Society
49th Annual Meeting of the Division of Plasma Physics
Volume 52, Number 11
Monday–Friday, November 12–16, 2007; Orlando, Florida
Session CO3: NSTX and General Spherical Tokamak
2:00 PM–4:48 PM,
Monday, November 12, 2007
Rosen Centre Hotel Room: Salon 9/10
Chair: Mickey Wade, General Atomics
Abstract ID: BAPS.2007.DPP.CO3.5
Abstract: CO3.00005 : Gyroradius-Scale Ion Gradients in NSTX*
2:48 PM–3:00 PM
Preview Abstract Abstract
The spherical torus geometry is well suited to compare experimental profiles on a fundamental transport scale. The low-field region in the low-aspect ratio NSTX along with a high spatial resolution charge exchange spectroscopy system make gyroradius-scale ion measurements possible. Ion temperature and density gradients with gyroradius-scale widths have been measured in some NSTX plasmas. Measured ion temperature changes of $\Delta T_i = 250-500$ eV are observed over $\Delta r \sim 1$ cm with total Larmor radius $\sim 1$ cm. Minimum gradient widths comparable to the larger banana orbit width would normally be expected from ``random walk'' arguments of neoclassical theory. Since radial electric field ($E_r$) gradients also vary on a gyro-radius scale, distortion of the gyro orbit is expected to cause orbit shrinking or orbit expansion , depending on the sign of $E_r$. Orbit shrinking removes the apparent discrepancy in the gradient width. \newline \newline  K. C. Shaing, A. Y. Aydemir, R. D. Hazeltine, Phys. Plasmas 5, 3680 (1998).
*This work supported by U.S. DOE Contract \# DE-AC02-76CH03073.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.DPP.CO3.5
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