Fast-wave current drive in the Irvine torus.

Abstract

Steady-state electron currents were driven by fast waves with ${\ensuremath{\omega}}_{\mathrm{ci}}$\ensuremath{\ll}\ensuremath{\omega}\ensuremath{\ll}${\ensuremath{\omega}}_{\mathrm{ce}}$ in an initially current-free plasma in the Irvine Torus. Current direction was controlled by the fast-wave phased-array antenna. Low power experiments (l25 W) generated up to 1.3 A of electron current with a peak effeciency of \ensuremath{\eta}=InR/P\ensuremath{\simeq}(6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}2}$ A/W)(${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$)m. Up to 14% of the wave energy was converted to poloidal magnetic field energy.