Experimental Verification of the Kruskal-Shafranov Stability Limit in Line-Tied Partial Toroidal Plasmas
Authors: E. Oz, C.E. Myers, M. Yamada, H. Ji, R.M.. Kulsrud and J. Xie
Abstract:
The stability properties of partial toroidal flux ropes are studied in detail in the laboratory, motivated by
ubiquitous arched magnetic structures found on the solar surface. The flux ropes studied here are magnetized
arc discharges formed between two electrodes in the Magnetic Reconnection Experiment (MRX) [Yamada et
al., Phys. Plasmas, 4, 1936 (1997)]. The three dimensional evolution of these flux ropes is monitored by a
fast visible light framing camera, while their magnetic structure is measured by a variety of internal magnetic
probes. The flux ropes are consistently observed to undergo large-scale oscillations as a result of an external
kink instability. Using detailed scans of the plasma current, the guide field strength, and the length of the
flux rope, we show that the threshold for kink stability is governed by the Kruskal-Shafranov limit for a flux
rope that is held fixed at both ends (i.e., qa = 1).
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Submitted to: Physics of Plasmas (May 2011)
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Download PPPL-4642 (pdf 1.26 MB 7 pp)
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