Toroidicity effects in electrostatic drift wave turbulence in Tokamaks. II. The incoherent response

Abstract

For pt. I see ibid., vol.29, no.8, pp.993-1018 (1987). The concept of clumps is used in the Tokamak turbulence theory. Using the Misguich-Balescu stochastic orbit treatment (1985), the two-point fluctuation correlation equation is studied in detail. It is shown that the Hirshman-Molvig effect (1979) has a special influence on the clumps theory: the general quasilinear diffusion regime does not exist in Tokamaks. It is found that the clumps cannot be considered only as a destabilizing mechanism ('clumps-induced instability'), the presence of Delta omega (the frequency width at fixed wavenumber) stabilizes the plasma. It is also shown that Delta omega approximately omega c> omega as a result of the Hirshman-Molvig effect on the propagator. The saturation appears as a result of the balance between the clumps and the ion Compton scattering. The fluctuation spectrum is estimated, the large ktheta asymptotic form is ktheta -103/.