Anomalous particle and electron energy pinches

Interest in plasma pinches has recently increased due to the observation in electron cyclotron heated (ECH) plasmas in the Doublet III-D (DIII-D) tokamak [Plasma Physics and Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] of an electron energy pinch. Previous work on drift wave-induced particle and electron energy pinches concluded that they were only possible in strictly collisionless plasmas, ν*=0, an assumption not applicable to electron-cyclotron heating experiments. In the present work it is shown that a more detailed quasilinear analysis predicts a particle pinch at moderate collisionality, ν*=0.2 to 1.0, when the electron temperature gradient parameter ηe is in the range ηe=2 to 3. Further, the quasilinear analysis is expanded to include the effects of turbulent resonance broadening on the circulating electrons. It is then found that, in addition to a particle pinch (qualitatively the same as the quasilinear prediction), a simultaneous particle and electron energy pinch at moderate collisionality can occur at ηe≂1, which is lower than in ECH experiments where ηe=2 to 3.