A momentum balance equation including the effect of ion orbit loss is employed to discuss the poloidal plasma rotation in tokamaks. It is found that in a steady state, the high-energy collisionless ions leave the system through an ion orbit loss mechanism and the low-energy collisional ions convect into the system as viscosity-driven flux in such a way that there is no net flux-surface-averaged radial current across the flux surface. The value of poloidal rotation necessary to maintain steady-state ambipolarity is different from that of the conventional neoclassical theory. This confirms the previous results [Phys. Rev. Lett. 63, 2369 (1989)]. It is also shown, by considering the effects of incompressible flow in the phase space described by the orbit-averaged Coulomb collision operator, that the ion orbit loss flux is intimately related to the plasma viscosity.
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Physics and Astronomy(all)
- Fluid Flow and Transfer Processes