RENORMALIZATION-GROUP THEORY OF PLASMA MICROTURBULENCE

The dynamical renormalization-group methods are applied to the gyrokin etic equation describing drift-wave turbulence in plasmas. As in both magnetohydrodynamic and neutral turbulence, small-scale fluctuations a ppear to act as effective dissipative processes on large-scale phenome na. A linear renormalized gyrokinetic equation is derived. No artifici al forcing is introduced into the equations and all the renormalized c orrections are expressed in terms of the fluctuating electric potentia l. The link with the quasilinear limit and the direct interaction appr oximation is investigated. Simple analytical expressions for the anoma lous transport coefficients are derived by using the linear renormaliz ed gyrokinetic equation. Examples show that both quasilinear and Bohm scalings can be recovered depending on the spectral amplitude of the e lectric potential fluctuations.