Investigations of the magnetic structure and the decay of a plasma-gun-generated compact torus

Turner, W.C.

doi:10.1063/1.864345

Cited by 101 publications

(46 citation statements)

References 22 publications

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“…This topological change has a profound effect on the nature of the relaxed states (Turner et al 1983;Taylor 1985Taylor , 1986Taylor , 1992.…”

Section: Spherical Systems I: Spheromakmentioning

confidence: 99%

“…Experimental data In figure 32 the poloidal and toroidal field profiles given by (11.8) are compared with those measured in the BETA II experiment (Turner et al 1983). This has a cylindrical flux conserver with h/a ∼ 1 and a plasma created by a coaxial gun (see figure 31a).…”

Section: Spheromak Eigenfunctionsmentioning

confidence: 99%

“…FIGURE 31. Methods to create a spheromak discharge: (a) by plasma gun (reproduced with permission from Turner et al 1983Turner et al , copyright 1983, AIP Publishing LLC), (b) by combined θ -z discharge (reprinted with permission from Goldenbaum et al 1980Goldenbaum et al , copyright 1980 by the American Physical Society) and (c) by inductive flux core in S-1 (reprinted with permission from Yamada et al 1981Yamada et al , copyright 1981 by the American Physical Society).…”

Section: Relaxed States Of a Spheromakmentioning

confidence: 99%

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Special topics in plasma confinement

Taylor

Newton

2015

J. Plasma Phys.

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These notes are based on lectures given by one of us (J.B.T.) at the University of Texas in Austin in 1991. Part I concerns some basic features of plasma confinement by magnetic fields as an introduction to an account of plasma relaxation in Part II. Part III discusses confinement by magnetic mirrors, especially minimum-B systems. It also includes a general discussion of adiabatic invariants and of the principle of maximal ordering in perturbation theory. Part IV is devoted to the analysis of perturbations in toroidal plasmas and the stability of ballooning modes. PREFACEThe theory of plasma confinement is complicated and incomplete. Because current textbooks do not include material at the frontier of research, it is hard for students and researchers to become familiar with the state of the art. Bryan Taylor's notes are presented here to start filling that gap. Although based on lectures from over twenty years ago, they provide much needed clarity in selected areas of current plasma confinement research. Of course much of the original work on which these notes are based is by Bryan Taylor and collaborators; but here, he and Sarah Newton draw the many threads together. Indeed, while some may find the results familiar, the insight is fresh and enlightening. The research frontier is just beyond these notes. Some of the outstanding questions are posed and some are left to the reader to discern. For example, we still need to know: how fast plasmas relax; how three-dimensional reconnection works; how ballooning modes saturate and; how minimum B ideas can improve toroidal devices. The insights here will help anyone wanting to answer those and other questions.

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“…This topological change has a profound effect on the nature of the relaxed states (Turner et al 1983;Taylor 1985Taylor , 1986Taylor , 1992.…”

Section: Spherical Systems I: Spheromakmentioning

confidence: 99%

Section: Spheromak Eigenfunctionsmentioning

confidence: 99%

Section: Relaxed States Of a Spheromakmentioning

confidence: 99%

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Special topics in plasma confinement

Taylor

Newton

2015

J. Plasma Phys.

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“…The plasma conducts electrical current between electrodes linked by open magnetic field lines, and nonlinear effects convert toroidal magnetic flux into poloidal flux [1][2][3]. While inductive effects can contribute to formation, symmetry-breaking magnetic fluctuations are required for sustainment [4,5], as found experimentally in SPHEX [6].…”

mentioning

confidence: 99%

Numerical Investigation of Transients in the SSPX Spheromak

et al. 2005

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Nonlinear plasma simulations of the Sustained Spheromak Physics Experiment demonstrate the role of transient effects in establishing a toroidal magnetic structure that confines internal energy. Magnetohydrodynamics modeling with temperature-dependent transport coefficients compares well with experimental measurements and shows that the second current pulse improves confinement by keeping the q profile from falling below the value of 1/2, suppressing resonant m = 1, n = 2 fluctuations.

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“…where K = A · Bd 3 r is the magnetic helicity Turner et al, 1983) of the system. Energy dissipating processes that conserve helicity (e.g., magnetic reconnection) will cause an isolated system to relax to a minimum energy state with the lowest λ allowed by the boundary conditions (Taylor, 1974).…”

Section: Properties Of λ λ λmentioning

confidence: 99%

Spheromaks, solar prominences, and Alfvén instability of current sheets

2014

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Three related efforts underway at Caltech are discussed: experimental studies of spheromak formation, experimental simulation of solar prominences, and Alfvén wave instability of current sheets. Spheromak formation has been studied by using a coaxial magnetized plasma gun to inject helicity-bearing plasma into a very large vacuum chamber. The spheromak is formed without a flux conserver and internal λ profiles have been measured. Spheromak-based technology has been used to make laboratory plasmas having the topology and dynamics of solar prominences. The physics of these structures is closely related to spheromaks (low β, force-free, relaxed state equilibrium) but the boundary conditions and symmetry are different. Like spheromaks, the equilibrium involves a balance between hoop forces, pinch forces, and magnetic tension. It is shown theoretically that if a current sheet becomes sufficiently thin (of the order of the ion skin depth or smaller), it becomes kinetically unstable with respect to the emission of Alfvén waves and it is proposed that this wave emission is an important aspect of the dynamics of collisionless reconnection.

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Investigations of the magnetic structure and the decay of a plasma-gun-generated compact torus

Abstract: Design and experimental results of a new electron gun using a magnetic multipole plasma generator Rev. Sci. Instrum. 62, 761 (1991);

Cited by 101 publications

References 22 publications

Special topics in plasma confinement

Special topics in plasma confinement

Numerical Investigation of Transients in the SSPX Spheromak

Spheromaks, solar prominences, and Alfvén instability of current sheets

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