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Abstract
The vertical motion of a tokamak plasma is analytically modelled during its nonlinear phase by a freemoving currentcarrying 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 nonlinear "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 language  English 

Article number  022516 
Pages (fromto)  022516 
Journal  Physics of Plasmas 
Volume  25 
Issue number  2 
DOIs  
Publication status  Published  1 Feb 2018 
Externally published  Yes 
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Dive into the research topics of 'Algebraic motion of vertically displacing plasmas'. Together they form a unique fingerprint.Activities
 3 Contribution or participation in a conference

Sherwood Fusion Theory Conference
David Pfefferle (Participant)
1 May 2017 → 3 May 2017Activity: Conferences and workshops › Contribution or participation in a conference

59th Annual Meeting of the APS Division of Plasma Physics
David Pfefferle (Keynote speaker/Invited speaker)
23 Oct 2017 → 27 Oct 2017Activity: Conferences and workshops › Contribution or participation in a conference

Theory and Simulation of Disruptions Workshop
David Pfefferle (Keynote speaker/Invited speaker)
17 Jul 2017 → 19 Jul 2017Activity: Conferences and workshops › Contribution or participation in a conference