Flux ropes and 3D dynamics in the relaxation scaling experiment

Intrator, T.; Sun, Xuan; Dorf, L.; Sears, J.; Feng, Yan; Weber, T.; Swan, H.

doi:10.1088/0741-3335/55/12/124005

Cited by 10 publications

(11 citation statements)

References 45 publications

(68 reference statements)

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“…For example, what are the underlying physical mechanisms of the merging process, and what are the merging statistics in three-dimensional (3-D) systems? On the experimental side, there have been detailed investigations of the 2-D dynamics during the merger of pairs of annular flux ropes (Yamada et al 1997;Jara-Almonte et al 2016) and others focusing on the 3-D dynamics of flux ropes (Furno et al 2005;Gekelman, Lawrence & Van Compernolle 2012;Intrator et al 2013;Sears et al 2014;Gekelman et al 2016).…”

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confidence: 99%

Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer

2020

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We report on an analytical and numerical study of the dynamics of a three-dimensional array of identical magnetic flux tubes in the reduced-magnetohydrodynamic description of the plasma. We propose that the long-time evolution of this system is dictated by flux-tube mergers, and that such mergers are dynamically constrained by the conservation of the pertinent (ideal) invariants, viz. the magnetic potential and axial fluxes of each tube. We also propose that in the direction perpendicular to the merging plane, flux tubes evolve in a critically balanced fashion. These notions allow us to construct an analytical model for how quantities such as the magnetic energy and the energy-containing scale evolve as functions of time. Of particular importance is the conclusion that, like its two-dimensional counterpart, this system exhibits an inverse transfer of magnetic energy that terminates only at the system scale. We perform direct numerical simulations that confirm these predictions and reveal other interesting aspects of the evolution of the system. We find, for example, that the early time evolution is characterized by a sharp decay of the initial magnetic energy, which we attribute to the ubiquitous formation of current sheets. We also show that a quantitatively similar inverse transfer of magnetic energy is observed when the initial condition is a random, small-scale magnetic seed field.

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confidence: 99%

Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer

2020

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“…In more recent history, a lot of attention was directed also to the effect of the line-tying at the ends of the equilibrium pinch (e.g., Refs. [17][18][19][20]. Unlike Refs.…”

Section: Introductionmentioning

confidence: 94%

Evolution of helical perturbations in a thin-shell model of an imploding liner

Ryutov

Dorf

2014

Physics of Plasmas

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A thin-shell model of the liner stability has been revisited and applied to the stability of the helical perturbations. Several stages of the implosion have been identified, starting from a long initial "latent" phase of an almost resting liner, continuing to the second stage of a rapid contraction and significant perturbation growth, and then transitioning to the third stage where perturbations become ballistic and highly non-linear. The stage of stagnation and rebound is beyond the scope of this paper. An importance of vorticity conservation during the late stages is emphasized. Nonlinear evolution of perturbations is followed up to the point of the formation of cusp structures. Effects of in-surface flows and of their enhancement due to the vorticity conservation are discussed. It is shown that the pre-machined perturbations created only on the outer surface of the liner grow much slower than one could anticipate. The limitations on the thin-shell description are discussed. V C 2014 AIP Publishing LLC.

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“…Early testing of a prototype plasma gun was carried out on the Relaxation Scaling Experiment (RSX) experiment, 44,45 which has improved diagnostic access compared to MSX and is capable of producing axial magnetic fields of 0.12 T, approaching the lower range of reverse bias used in MSX. At typical operational parameters (150 psi line pressure, several hundred ls puff duration, and peak currents of $2 kA), peak plasma density 20 cm downstream of the gun nozzle was measured via Langmuir probe to be $3 Â 10 19 m -3 with a $50% reduction over the next 10 cm.…”

Section: A Initial Conditionsmentioning

confidence: 99%

Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch

2015

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Injection of plasma via an annular array of coaxial plasma guns during the pre-ionization phase of field-reversed configuration (FRC) formation is shown to catalyze the bulk ionization of a neutral gas prefill in the presence of a strong axial magnetic field and change the character of outward flux flow during field-reversal from a convective process to a much slower resistive diffusion process. This approach has been found to significantly improve FRC formation in a conical h-pinch, resulting in a $350% increase in trapped flux at typical operating conditions, an expansion of accessible formation parameter space to lower densities and higher temperatures, and a reduction or elimination of several deleterious effects associated with the pre-ionization phase. V C 2015 AIP Publishing LLC.

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Flux ropes and 3D dynamics in the relaxation scaling experiment

Cited by 10 publications

References 45 publications

Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer

Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer

Evolution of helical perturbations in a thin-shell model of an imploding liner

Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch

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