Microturbulence reduction during counter neutral beam injection in the DIII-D tokamak

When significant neutral beam power is injected in the direction counter to the plasma current in the DIII-D tokamak [Plasma Physics and Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159], a prompt reduction in electrostatic turbulence is observed, principally in shorter wavelength modes. The core radial electric field reverses polarity and becomes sheared as the fluctuations reduce. As the electric field continues evolving, a larger reduction is observed on a slower time scale. These observations support the possibility of controlling turbulence and its associated transport by controlling the internal radial electric field. copyright 1996 American Institute of Physics