Toroidal consideration of plasma response to penetration of an external low frequency helical perturbation into a tokamak edge plasma

Abstract

For an adequate comparison with TEXTOR-DED experiments [1] the theoretical treatment of the DED operation, with the plasma response has been taken into account, are made in the toroidal geometry on the basis of two-fluid MHD PACS: 52.55.Dy; 52.55.Fa; 52.55.Rk

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

“…This reflects the single-fluid resistive MHD description of the reference. Turning to [11], though this reference does not include a calculation of coupling to coil currents, it is worth mentioning that it finds resonance half-widths of the same length scale as ours. Neither [7] nor [11] describes the poloidal mode coupling due to toroidal geometry or the finite Larmor radius effect treated by us, though [11] includes the effect of particle drift due to a radial equilibrium field in its DED analysis.…”

“…References [7] and [11] calculate torques exerted by the DED field on the plasma; only the former reference deals with the [3,1] coil setting to which the foregoing estimations of the present section apply (see the 'resonant' case of [7]). For f = 10 kHz it finds a 'typical' poloidal torque of ∼20 Nm.…”

“…Related earlier experimental and theoretical studies on penetration of rotating low frequency (LF) fields into tokamak plasmas [3,4] continues in recent experiments on the HYBTOK-II tokamak [5]. More exclusively theoretically oriented study is an active endeavour [6][7][8][9][10][11][12] which includes modelling of DED coils for the Tokamak Chauffage Alfvén Brésilien (TCABR) [9]. The present work models the DED coils recently installed on TEXTOR, treating them as an antenna producing energy deposition and associated plasma flow in the upper DED frequency band 5-10 kHz, these quantities being presumably linked to the positive DED features cited above.…”

Modelling of the field line penetration and force transfer by the dynamic ergodic divertor of TEXTOR

“…Based on this idea, several approaches for the description of the DED-field in the plasma have been performed using a cylindrical approximation of the plasma. In the first attempt, the plasma velocity was treated in a rather simplified way; namely, only the radial velocity component [17,18] was considered; later the model was extended using additionally the azimuthal one [19]. In this model, we take all components of the linearized perturbed cold MHD equations namely:…”