Plasma convection near the threshold for MHD instability in nonparaxial magnetic confinement systems

Пастухов, В. П.; Chudin, N. V.

doi:10.1134/1.1416202

Cited by 34 publications

(35 citation statements)

References 13 publications

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“…For the high power heat source, quasilinear transport was present and large but was quickly replaced by the non-linear stage. A similar finding was reported by Pastukhov [9]. He observed that the quasilinear transport started to smooth the profiles, but was not dominant and was replaced by non-linear global plasma motion.…”

Section: Summary Of Simulation Resultssupporting

confidence: 88%

“…This behavior coincides with that seen by Pastukhov [9] in the quasi-stable state, while Makhnin reported smaller scale incoherent turbulence. Also, the development of large-scale convective cells in the nonlinear regime is supported by the theoretical analysis presented by Yoshizawa et.al.…”

Section: Numerical Simulationssupporting

confidence: 89%

“…The simplification arises because the hard core Z-pinch interchange mode requires a 2-D rather than a 3-D simulation. Pastukhov and Chudin modeled the system of reduced MHD equations for an unstable hard core Z-pinch plasma [9][10]. The key result was that violation of the marginal stability did not lead to a disruption, but resulted in non-local anomalous transport through the global plasma motion.…”

Section: Introductionmentioning

confidence: 99%

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Quasilinear theory of interchange modes in a closed field line configuration

2007

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Two important issues for any magnetic fusion configuration are the maximum achievable values of beta and energy confinement time when ideal magnetohydrodynamic (MHD) modes are excited. It is well known that the excitation of the MHD unstable modes typically can lead to violent restructuring of the plasma profiles. The particle and energy transport associated with these modes normally dominates all other transport mechanisms and can lead to plasma disruptions and a rapid loss of energy. This paper analytically investigates the transport of particle density, energy and magnetic field due to the ideal MHD interchange mode in a closed line system using the quasilinear approximation. The transport equations are derived for a static plasma in a hard core Z-pinch configuration and generalized to an arbitrary axisymmetric toroidal closed poloidal filed line configuration. It is shown that violation of the marginal stability criterion leads to rapid quasilinear transport that drives the pressure profile back to its marginal profile and forces the particle density to be inversely proportional to / dl B ∫ . The applicability of the quasilinear approximation is numerically tested for the hard core Z-pinch magnetic configuration using a full nonlinear code.

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Section: Summary Of Simulation Resultssupporting

confidence: 88%

Section: Numerical Simulationssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Quasilinear theory of interchange modes in a closed field line configuration

2007

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“…Non-linear studies indicate that large-scale convective cells will form when the MHD stability limit is weakly violated, which results in the circulation of plasma between the hot core and the cooler edge region [6]. Studies have also predicted that the confined plasma can be stable to low frequency (drift wave) modes when η=dln Te/d ln ne>2/3 [7].…”

Section: Introductionmentioning

confidence: 99%

Confinement improvement with magnetic levitation of a superconducting dipole

et al. 2009

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Abstract. We report the first production of high beta plasma confined in a fully levitated laboratory dipole using neutral gas fueling and electron cyclotron resonance heating. The pressure results primarily from a population of energetic trapped electrons that is sustained for many seconds of microwave heating provided sufficient neutral gas is supplied to the plasma. As compared to previous studies in which the internal coil was supported, levitation results in improved particle confinement that allows higher-density, high-beta discharges to be maintained at significantly reduced gas fueling. Elimination of parallel losses coupled with reduced gas leads to improved energy confinement and a dramatic change in the density profile. Improved particle confinement assures stability of the hot electron component at reduced pressure. By eliminating supports used in previous studies, cross-field transport becomes the main loss channel for both the hot and the background species. Interchange stationary density profiles, corresponding to an equal number of particles per flux tube, are commonly observed in levitated plasmas.

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“…In fact, Pastukhov and Chudin [23,24] show that this scaling persists even during the nonlinear phase of the evolution of the interchange instability.…”

Section: Cylindrical Resultsmentioning

confidence: 99%