EFFECTS OF ORBIT SQUEEZING ON TRANSPORT FLUXES

When the ratio mu(1)(i)/mu(1)(e) is of the order of unity, electron tr ansport fluxes such as bootstrap current can be affected by the ion or bit squeezing. Here, mu(1)(e) is the electron viscous coefficient, and mu(1)(i) is the ion viscous coefficient with the effects of ion orbit squeezing included. The condition mu(1)(i)/mu(1)(e) similar to 1 can be satisfied for plasmas, such as those in enhanced reversed shear (ER S) mode, with ion temperature greater than electron temperature and or bit squeezing factor S much greater than 1. Transport fluxes for both standard squeezed banana orbits and for squeezed orbits close to the m agnetic axis are calculated for a large aspect ratio tokamak. It is fo und that ion heat flux and bootstrap current are reduced in ERS-like p lasmas. Furthermore, the bootstrap current density does not vanish on the magnetic axis for a parabolic pressure profile in minor radius r d ue to the finite value of the fraction of trapped particles. This make s it possible to operate tokamaks in steady state. (C) 1997 American I nstitute of Physics.