Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium of an internal ring current system

Furukawa, Masato

doi:10.1063/1.4862037

Cited by 8 publications

(7 citation statements)

References 28 publications

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“…In this section, we show the results of the numerical analysis based on a numerical code RTEQ (Ring Trap EQuilibrium) developed by Furukawa. 13…”

Section: Numerical Analysismentioning

confidence: 99%

“…While the functional form of the pressure tensor remains arbitrary in such a fluid model, parametric studies on the effect of anisotropic pressure have been performed using numerical analysis. 12,13 We have yet to build a consistent relationship between the kinetic description and the magneto-fluid model and to provide a physical reason for selecting an appropriate form of the pressure tensor.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic construction of the high-beta anisotropic-pressure equilibrium in the magnetosphere

2021

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A theoretical model of the high-beta equilibrium of magnetospheric plasmas was constructed by consistently connecting the (anisotropic pressure) Grad-Shafranov equation and the Vlasov equation. The Grad-Shafranov equation was used to determine the axisymmetric magnetic field for a given magnetization current corresponding to a pressure tensor. Given a magnetic field, we determine the distribution function as a specific equilibrium solution of the Vlasov equation, using which we obtain the pressure tensor. We need to find an appropriate class of the distribution function for these two equations to be satisfied simultaneously. Here, we consider the distribution function that maximizes the entropy on the submanifold specified by the magnetic moment. This is equivalent to the reduction of the canonical Poisson bracket to the noncanonical one having the Casimir corresponding to the magnetic moment. The pressure tensor then becomes a function of the magnetic field (through the cyclotron frequency) and flux function, satisfying the requirement of the Grad-Shafranov equation.

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“…In this section, we show the results of the numerical analysis based on a numerical code RTEQ (Ring Trap EQuilibrium) developed by Furukawa. 13…”

Section: Numerical Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetic construction of the high-beta anisotropic-pressure equilibrium in the magnetosphere

2021

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“…In the higher beta regime, the nonlinear effect of the self-magnetic field diminishes Wp, thus the linear relation underestimates the beta. The possible anisotropic electron pressure (due to resonance heating of the perpendicular component) also provides an underestimate of the beta in the MHD fitting [5].…”

Section: Conventional Operation Regimementioning

confidence: 99%

Improved beta (local beta >1) and density in electron cyclotron resonance heating on the RT-1 magnetosphere plasma

Nishiura¹,

Yoshida²,

Saitoh³

et al. 2015

Nucl. Fusion

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This study reports the recent progress in improved plasma parameters of the RT-1 device. Increased input power and the optimized polarization of electron cyclotron resonance heating (ECRH) with an 8.2 GHz klystron produced a significant increase in electron beta, which is evaluated with an equilibrium analysis of Grad-Shafranov equation. The peak value of the local electron beta e was found to exceed 1. In the high beta and high-density regime, the density limit was observed for H, D, and He plasmas. The line average density was close to the cut off density for 8.2 GHz ECRH. The density limit exists even at the low beta region. This result indicates the density limit is caused by the cutoff density rather than by the beta limit. From the analysis of interferometer data, the uphill diffusion produces a peaked density profile beyond the cutoff density. The ring trap 1 (RT-1) device is a "laboratory magnetosphere" created by a levitated superconducting ring magnet, which is dedicated to studying physical processes in the vicinity of a magnetic dipole. An inhomogeneous magnetic field creates interesting properties of plasmas that are degenerate in homogeneous (or zero) magnetic fields. The RT-1 experiment has demonstrated the self-organization of a plasma clump with a steep density gradient; a peaked density distribution is spontaneously created through "uphill diffusion" [1-3]. Without direct ion heating, the ions remain cold being virtually decoupled with the hot component (> 10 keV) and low density (< 10 18 m-3) electrons. For the study of two-fluid effects on the plasma flow in a high ion beta plasma, two scenarios are investigated to realize ion heating. Scenario A is an ion heating by an ion cyclotron resonance heating (ICRH). Scenario B is a collision relaxation between electrons and ions. In both cases, achieving the electron density > 10 18 m-3 as a target plasma is essential. The operation regime of the RT-1 device has been investigated and extended to a higher electron density and beta by an increase of the ECRH power up to ~ 50 kW with an 8.2 GHz klystron [4]. The ECRH beams from two launchers L#1 and L#2 were injected with both O-modes. The result is shown as the "conventional operation regime" (gray area) (see Fig. 1). After an upgrade in the ECRH system, the polarizations of millimeter waves from two launchers L#1 and L#2 were changed to optimize the deposition and heating efficiency. A twisted waveguide was inserted in the transmission line to rotate the polarization direction of 90 degrees from O-to X-modes.

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“…However, when the plasma pressure becomes comparable to the pressure of the dipole magnetic field (i.e., the so-called beta ratio is of order unity; see [20]), we have to adjust the magnetic field to take into account the spontaneous component. This can be done by solving the Grad-Shafranov equation for ψ with the plasma pressure given by the distribution function (to take into account the pressure anisotropy, we have to use the generalized Grad-Shafranov equation [23,24]). We also assumed charge neutrality, and put the electric potential φ = 0.…”

Section: Remarkmentioning

confidence: 99%

Self-organization in foliated phase space: Construction of a scale hierarchy by adiabatic invariants of magnetized particles

Yoshida

Mahajan

2014

Progress of Theoretical and Experimental Physics

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Adiabatic invariants foliate phase space, and impart a macro-scale hierarchy by separating microscopic variables. On a macroscopic leaf, long-scale ordered structures are created while maximizing entropy. A plasma confined in a magnetosphere is invoked to unveil the organizing principle -in the vicinity of a magnetic dipole, the plasma self-organizes to a state with a steep density gradient. The resulting nontrivial structure has maximum entropy in an appropriate, constrained phase space. One could view such a phase space as a leaf foliated in terms of Casimir invariants -adiabatic invariants measuring the number of quasi-particles (macroscopic representation of periodic motions) are identified as the relevant Casimir invariants. The density clump is created in response to the inhomogeneity of the energy levels (frequencies) of the quasi-particles.

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Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium of an internal ring current system

Cited by 8 publications

References 28 publications

Kinetic construction of the high-beta anisotropic-pressure equilibrium in the magnetosphere

Kinetic construction of the high-beta anisotropic-pressure equilibrium in the magnetosphere

Improved beta (local beta >1) and density in electron cyclotron resonance heating on the RT-1 magnetosphere plasma

Self-organization in foliated phase space: Construction of a scale hierarchy by adiabatic invariants of magnetized particles

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