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Title: Algebraic motion of vertically displacing plasmas

Abstract

In this paper, the vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to come in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear “sinking” behaviour shown to be algebraic and decelerating. Finally, the acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quenchmore » dynamics precipitating loss of plasma current.« less

Authors:
ORCiD logo [1];  [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1429048
Alternate Identifier(s):
OSTI ID: 1422853
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 2; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; eddies; electronic circuits; condensed matter properties; electrical properties; plasma confinement; differential equations; classical electromagnetism

Citation Formats

Pfefferle, D., and Bhattacharjee, A. Algebraic motion of vertically displacing plasmas. United States: N. p., 2018. Web. doi:10.1063/1.5011176.
Pfefferle, D., & Bhattacharjee, A. Algebraic motion of vertically displacing plasmas. United States. doi:10.1063/1.5011176.
Pfefferle, D., and Bhattacharjee, A. Tue . "Algebraic motion of vertically displacing plasmas". United States. doi:10.1063/1.5011176. https://www.osti.gov/servlets/purl/1429048.
@article{osti_1429048,
title = {Algebraic motion of vertically displacing plasmas},
author = {Pfefferle, D. and Bhattacharjee, A.},
abstractNote = {In this paper, the vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to come in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear “sinking” behaviour shown to be algebraic and decelerating. Finally, the acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.},
doi = {10.1063/1.5011176},
journal = {Physics of Plasmas},
number = 2,
volume = 25,
place = {United States},
year = {2018},
month = {2}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 2 works
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Figures / Tables:

Figure 1 Figure 1: Vertical drift of a plasma column due to the external eld by two divertor coils for varying values of s2 = γDELR (sets of curves with di erent colour, see legend) and h⁻2ϵ {0, 1/3, 2/3, 1} (bottom to top curves of same colour). The initial exponential behaviourmore » for T → –∞ is traced by the dashed colour lines. The in exion points, $\ddot{χ}$* = 0 are denoted with coloured circles. The black dotted line represents the explicit solution χ(T, h → ∞, s2→0). For better comparison, the x-axis is adjusted so that the span is identical for the three wall models.« less

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    Figures / Tables found in this record:

      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.