Current drive and helicity injection

Jensen, T. H.; Chu, M. S.

doi:10.1063/1.864602

Cited by 193 publications

(121 citation statements)

References 12 publications

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“…It is interesting to cast the theory of relaxed states in a general form that illustrates the connection between different types of relaxed state (Jensen & Chu 1984;Taylor 1986). (Even though it is not a convenient way to study specific examples.…”

Section: General Theory Of Relaxed Toroidal Statesmentioning

confidence: 99%

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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Section: General Theory Of Relaxed Toroidal Statesmentioning

confidence: 99%

Special topics in plasma confinement

Taylor

Newton

2015

J. Plasma Phys.

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“…30 In a freely expanding plasma, rapid increase in the toroidal flux modifies the rotational transform profile of the open field lines quickly and hence avoids locking to a primary eigenmode that could destroy the jet morphology at early stage of the expansion. If the plasma is indeed force-free and eventually Taylor relaxed, Jensen-Chu resonance 31 predicts a spheromak solution for the entire radio lobe. In a more realistic partially relaxed plasma, Jensen-Chu resonances are regularized and more complicated magnetic structures become accessible.…”

Section: -4mentioning

confidence: 99%

Miniconference on astrophysical jets

Bellan

2005

Physics of Plasmas

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This miniconference brought together observers of astrophysical jets, analytic and numerical modelers of both astrophysical jets and spheromaks, and laboratory experimentalists. The purpose of the miniconference was to encourage interaction between these diverse groups and also expose the plasma physics community to the interesting plasma issues associated with astrophysical jets. The miniconference emphasized magnetically driven astrophysical jets and consisted of three half-day sessions. The order of presentation was approximately: observations and general properties, experiments, numerical models, and special topics.

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“…equation (20) ff. of Jensen & Chu (1984)) and has a robust topological interpretation (see e.g. Berger (1999) for a heuristic review or Arnold & Khesin (1998) for a more mathematical treatment) the most robust of the remaining IMHD invariants is widely accepted to be the magnetic helicity 2µ 0 K Ω , where, Bhattacharjee & Dewar (1982), we define the invariant K Ω as…”

Section: Helicity Conservation and Taylor Relaxationmentioning

confidence: 99%

“…As tangential B is to be a holonomic constraint rather than a natural boundary condition, we do not treat A on the boundary as freely variable and can constrain χ. Thus we do not need to use either the Bevir-Gray (subtraction of products of toroidal and poloidal loop integrals, Bevir & Gray (1982)) or relative helicity (subtraction of vacuum-field helicity, Jensen & Chu (1984)) modifications of the helicity, the latter fact also implying there is no physical necessity to decompose the magnetic field into a vacuum (harmonic) and a plasma-current-generated component (though it may still be useful conceptually and mathematically, Yoshida & Giga (1990), Yoshida & Dewar (2012)). …”

Section: Helicity Conservation and Taylor Relaxationmentioning

confidence: 99%

Variational formulation of relaxed and multi-region relaxed magnetohydrodynamics

et al. 2015

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Ideal magnetohydrodynamics (IMHD) is strongly constrained by an infinite number of microscopic constraints expressing mass, entropy and magnetic flux conservation in each infinitesimal fluid element, the latter preventing magnetic reconnection. By contrast, in the Taylor relaxation model for formation of macroscopically self-organized plasma equilibrium states, all these constraints are relaxed save for the global magnetic fluxes and helicity. A Lagrangian variational principle is presented that leads to a new, fully dynamical, relaxed magnetohydrodynamics (RxMHD), such that all static solutions are Taylor states but also allows state with flow. By postulating that some long-lived macroscopic current sheets can act as barriers to relaxation, separating the plasma into multiple relaxation regions, a further generalization, multi-region relaxed magnetohydrodynamics (MRxMHD) is developed.

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Current drive and helicity injection

Cited by 193 publications

References 12 publications

Special topics in plasma confinement

Special topics in plasma confinement

Miniconference on astrophysical jets

Variational formulation of relaxed and multi-region relaxed magnetohydrodynamics

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