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poster.pdf2007-03-28 14:47:49Scott Hsu

Experimental study of driven magnetic relaxation in simply-connected and low aspect ratio geometries

Author: Scott C Hsu
Requested Type: Poster Only
Submitted: 2006-12-18 15:17:36

Co-authors: X. Z. Tang, M. E. Light

Contact Info:
MS E526
Los Alamos, NM   87545

Abstract Text:
The Driven Relaxation Experiment (DRX) is a new laboratory plasma experiment at Los Alamos, with first plasma expected in early 2007. The initial physics goal of DRX is to form and sustain simply-connected driven-relaxed plasmas above the first Jensen-Chu linear resonance of the force-free equation (where the first resonance is the "flipped" Rosenbluth-Bussac spheromak). As was shown recently by Tang & Boozer (PRL, 2005), the linear resonances are regularized in partially relaxed systems, thus removing the energy barriers which have been thought to constrain relaxed states to exist only below the first resonance. DRX will apply an "over-driven" boundary condition at the coaxial gun source, with lambda_gun (~30 m^-1) three times the first resonant lambda of the cylindrical boundary (0.9 m diameter, 1.3 m long). The initial DRX power system will form and sustain the ~10 eV plasma for about 0.6 ms, which is about 10 Sweet-Parker reconnection times and sufficient for the plasma to reach a driven-relaxed steady-state. We will first measure the 2D structure of the equilibrium magnetic field and compare it with the first several linear eigenmodes of the force-free equation, and subsequently study the k-spectrum of the magnetic energy as well as the dynamics of relaxation. Future work, requiring new funding, will add a center stack and CHI system for studying physics issues of non-inductive startup in spherical tokamak geometry, as discussed by X. Z. Tang at this workshop. This work is supported by the LANL LDRD Program.

Characterization: A1,E3

1. Please do not schedule me for Wed afternoon or Thursday. I need to catch a flight out on Wed afternoon.

2. If possible, please place next to Xianzhu Tang if Tang gets a poster.

University of Maryland

Innovative Confinement Concepts Workshop
February 12-14, 2007
College Park, Maryland

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