A dynamical equation for self-sustained and pressure-driven turbulence in toroidal plasmas is derived. The growth rate of the dressed-test mode, which belongs to the subcritical turbulence, is obtained as a function of the turbulent transport coefficient. In the limit of a low fluctuation level, the mode has nonlinear instability and shows explosive growth. The growth rate vanishes when the driven transport reaches a stationary-turbulent level. The stationary solution is thermodynamically stable. The characteristic time, by which the stationary and self-sustained turbulence are established, scales with the ion-sound transit time and is accelerated by bad magnetic curvature. The influence of the pressure gradient as well as the radial electric field inhomogeneity are quantified.
All Science Journal Classification (ASJC) codes
- Nuclear Energy and Engineering
- Condensed Matter Physics