Algebraic motion of vertically displacing plasmas

D. Pfefferlé, A. Bhattacharjee

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

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. 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.
Original languageEnglish
Pages (from-to)022516
JournalPhysics of Plasmas
Volume25
Issue number2
DOIs
Publication statusPublished - 1 Feb 2018
Externally publishedYes

Fingerprint

conduction
vessels
vertical motion
sinking
plasma currents
rigid structures
eddy currents
halos
rods
Green's functions
penetration
wire
vacuum
electrical resistivity
expansion
profiles
interactions

Cite this

Pfefferlé, D. ; Bhattacharjee, A. / Algebraic motion of vertically displacing plasmas. In: Physics of Plasmas. 2018 ; Vol. 25, No. 2. pp. 022516.
@article{724bb6d07b5242e082240facc86d841b,
title = "Algebraic motion of vertically displacing plasmas",
abstract = "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. 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.",
author = "D. Pfefferl{\'e} and A. Bhattacharjee",
year = "2018",
month = "2",
day = "1",
doi = "10.1063/1.5011176",
language = "English",
volume = "25",
pages = "022516",
journal = "Physics of Plasmas",
issn = "1070-664X",
publisher = "American Institute of Physics",
number = "2",

}

Algebraic motion of vertically displacing plasmas. / Pfefferlé, D.; Bhattacharjee, A.

In: Physics of Plasmas, Vol. 25, No. 2, 01.02.2018, p. 022516.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Algebraic motion of vertically displacing plasmas

AU - Pfefferlé, D.

AU - Bhattacharjee, A.

PY - 2018/2/1

Y1 - 2018/2/1

N2 - 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. 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.

AB - 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. 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.

U2 - 10.1063/1.5011176

DO - 10.1063/1.5011176

M3 - Article

VL - 25

SP - 022516

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 2

ER -