Onset and Saturation of the Kink Instability in a Current-Carrying Line-Tied Plasma

Bergerson, W.F.; Forest, C. B.; Fiksel, G.; Hannum, David; Kendrick, R.; Sarff, J. S.; Stambler, S.

doi:10.1103/physrevlett.96.015004

Cited by 67 publications

(63 citation statements)

References 18 publications

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“…III. The finite rotation of the mode, which is also observed in other laboratory devices [10,23], is due to the plasma flow along the helically kinked plasma column. These findings may be of significance to solar and astrophysical flux ropes where the case of free ended ropes may be relevant and their reduced stability limit needs to be taken into account.…”

Section: Discussionsupporting

confidence: 62%

“…The system of second-order differential equations given by Eqs. (23,24) is numerically integrated using the experimental profiles providing the time evolution of the plasma flow velocity. Fig.…”

Section: Plasma Flowmentioning

confidence: 99%

“…[19][20][21] and references therein) and numerical investigations ( [22] and references therein). In laboratory environments, the kink stability of a plasma column with line-tied ends has been experimentally investigated in linear devices, where line-tying is attributed to the presence of highly conducting end plates [23], and in open systems to a local discontinuity for the Alfvén velocity that forms a virtual boundary around the system [8,10].…”

Section: Introductionmentioning

confidence: 99%

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Effects of boundary conditions and flow on the kink instability in a cylindrical plasma column

et al. 2007

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An experimental investigation of the kink instability is presented in a linear plasma column where one end is line-tied to the plasma source, and the other end is not line-tied and therefore free to slide over the surface of the end-plate. This latter boundary condition is a result of plasma sheath resistance that insulates, at least partially, the plasma from the end-plate. The helical m = 1 kink mode is observed to grow when the plasma current exceeds a threshold and, close to the criticality, is characterized by an axial mode structure with maximum displacement at the free axial boundary. Azimuthal rotation of the mode is observed such that the helically kinked column always screws into the free axial boundary. The kink mode structure, rotation frequency and instability threshold are accurately reproduced by a recent kink theory [D. D. Ryutov, et al., Phys. Plasmas 13, 032105 (2006)], which includes axial plasma flow and one end of the plasma column that is free to move due to a perfect non-line-tying boundary condition which is experimentally verified. A brief review of the kink theory and its predictions for the boundary conditions relevant in the present experiments are presented.

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Section: Discussionsupporting

confidence: 62%

Section: Plasma Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of boundary conditions and flow on the kink instability in a cylindrical plasma column

et al. 2007

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“…This direct matching condition does not exist in any of the prior linear flux rope experiments. [15][16][17][18][19] The results present here also represent the first experimental identification of q a = 1 stability in a partial toroidal system. Though this lack of dependence on toroidicity is not particularly surprising given the success of the KS theory in explaining tokamak stability, it does reinforce the applicability of these results to the kink stability properties of other partial toroidal plasmas such as those found in the solar corona.…”

Section: Summary and Discussionsupporting

confidence: 63%

Experimental verification of the Kruskal-Shafranov stability limit in line-tied partial-toroidal plasmas

Öz

Myers

et al. 2011

Physics of Plasmas

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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]. 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., q a = 1).

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“…Two recent review articles discuss these contributions in depth (Zweibel and Yamada 2009;Yamada et al 2010). Highlights include laboratory studies of flux rope dynamics, including reconnection in line tied plasmas and relaxation to a lower energy state (Bergerson et al 2006;Cothran et al 2009;Sun et al 2010), a criterion for the onset of fast collisionless reconnection mediated by the Hall effect (Yamada 2007) and studies of the electron diffusion layer, which clarify the mechanisms responsible for breaking the fieldlines and the apportionment of energy in the reconnection region (Ren et al 2008). These studies thus suggest a possible mechanism for triggering fast reconnection in solar flares and provide detailed information on how energy is apportioned among thermal and nonthermal electron and ion populations in solar reconnection.…”

Section: Reconnection In Starsmentioning

confidence: 99%

The impact of recent advances in laboratory astrophysics on our understanding of the cosmos

et al. 2012

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Abstract. An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena -the radiation and particle spectra we observe -have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling.

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Onset and Saturation of the Kink Instability in a Current-Carrying Line-Tied Plasma

Cited by 67 publications

References 18 publications

Effects of boundary conditions and flow on the kink instability in a cylindrical plasma column

Effects of boundary conditions and flow on the kink instability in a cylindrical plasma column

Experimental verification of the Kruskal-Shafranov stability limit in line-tied partial-toroidal plasmas

The impact of recent advances in laboratory astrophysics on our understanding of the cosmos

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