Current Drive operation in a In-blanket ICRF Ring Array

¹ Dept of Physics, University of Turin and INFN, Via P. Giuria 1 10125 Turin
² Ghent University, 9000 Ghent, Belgium

^* Corresponding author: gbosia@to.infn.it

Published online: 23 October 2017

Abstract

The currently predicted Current Drive (CD)efficiency in a tokamak reactor plasma is χ_CD ≤ 50 kA/MW for all auxiliary systems (NBCD, ICCD, ECCD). This would imply a relatively low reactor Q = P_electric /P_auxiliary and an extremely high power density (>10 MW/m²) at the plasma boundary, if injected through the vacuum vessel ports or by in-port launchers.. In a previous paper the concept of an Ion Cyclotron Ring Array (RA) of many elements, integrated in the reactor blanket first wall was proposed. An analysis of this RA operating in steady state Fast Wave Current Drive (FW CD) with all elements individually controlled in magnitude and phase is presented in this paper. For CD operation the RA is operated at low frequency (f ≈ 20MHz) so as to avoid the otherwise overwhelming RF power absorption by ions and α-particles. It is shown that the RA would feature a very directive radiation spectrum, a low power density operation (avoiding the drawbacks associated with high AC and DC potentials) and a potentially high flexibility of operation..