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 GP8: Poster Session III: Turbulence, Transport, and NL Processes; Fast Ignition and Laser-Plasma Interactions; Divertors, Edge Physics and Fueling; MHD Theory, Heating and Current Drive; Simulation: MHD; Optimal Helicon Source Performance
Tuesday, November 13, 2007
Rosen Centre Hotel Room: Grand Ballroom, 9:30am - 12:30pm
Abstract ID: BAPS.2007.DPP.GP8.9
Abstract: GP8.00009 : Exponential Frequency Spectrum in a Magnetized Plasma--UCLA
Preview Abstract Abstract
The frequency spectrum of density and temperature fluctuations associated with a controlled, electron temperature filament in a magnetized plasma is investigated. A hot, narrow electron-temperature structure is generated from injection of a small, low-voltage beam into the LAPD-U device. Fluctuations develop after an initial quiescent period dominated by classical electron heat transport. Coherent structures associated with drift-Alfven modes grow due to the electron temperature gradient, but eventually a broadband frequency spectrum emerges, which exhibits an exponential frequency dependence for frequencies less than a third of the ion cyclotron frequency. Similar spectra have been previously observed in totally different experimental situations, including in tokamak plasmas.. Using a variety of signal analysis techniques, it is found that the exponential frequency dependence arises from a series of individual, soliton-like pulses. The relationship of the width, occurrence-frequency and amplitude of individual pulses to the exponential spectral index is determined. The dependence of the formation and characteristics of the solitary pulses on heating power, and magnetic field is explored.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.DPP.GP8.9
The American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics.
1 Physics Ellipse, College Park, MD 20740-3844
Editorial Office 1 Research Road, Ridge, NY 11961-2701 (631) 591-4000
Office of Public Affairs 529 14th St NW, Suite 1050, Washington, D.C. 20045-2001 (202) 662-8700