Temporal behavior of the plasma current distribution in the ASDEX tokamak during lower-hybrid current drive

Abstract

Measurements of the time evolution of the current-density distribution in ASDEX show that lower-hybrid current drive leads to broader profiles, whereby q increases from q\ensuremath{\lesssim}1 to q>1 in the plasma central region. Simultaneously, the electron temperature is observed to peak, thus demonstrating that the lower-hybrid--driven current distribution is decoupled from the classical conductivity profile.