Analysis of loop voltage evolution in current drive experiments in the Phaedrus-T tokamak

Abstract

The loop voltage response in the low-frequency current drive experiments is analyzed in order to extract information about the current drive profile and efficiency. 0 1995 American Znstitute of Physics.after the RF turn-on, are flat within experimental uncertainty in the bulk of the plasma (Fig. 4). The average Z,,= 1.8kO.5 in the Ohmic phase is consistent with 'the measured plasma resistance of 13.5 & that implies Z&= 1.9 for the temperature profile obtained from the-Thomson scattering.' Upon the ~~ RF turn-on, Z& rises to 2.5t0.5.The Z,, profile flatness, together with the constancy-of the electron temperature profile, allows us to represent the corresponding Spitzer conductivity as a separable function of space and time: u(r,t) = [(t)&(r), with ir normalized in such a way that l= 1 in the Ohmic phase. The toroidal electric field diffusion in such a case has been analyzed in the companion paper.3 Characterizing current drive by the source function S = JCdl&, where J, is the driven current density, the edge loop voltage change, for a constant total plasma current, can be expressed as 'L..

Turbulence and transport in the scrape-off layer TCABR tokamak

“…We study how the rf injection affects the total transport in the scrape-off layer and the part of this transport carried out by intermittent convection due to bursts propagating radially. As in other tokamaks [14], in TCABR Alfvén waves have been used to generate the non-inductive current drive [13].…”