Effects of rectangular cells applied to the simulation of toroidal pinch plasmas

The effect of simulation errors at the boundary on the results of plasma simulation of any cross section was studied. Two-fluid MHD equations were used for the simulation. The numerical calculation was performed for the circular cross section of plasma. When there was no poloidal field, the instability of m = 4 or m = 8 due to the error of plasma boundary arose. With increasing poloidal field intensity, the instability was stabilized, first m = 8 and next m = 4. The growth rate of the instability agreed with the growth rate of gravity instability due to the inertia force of plasma. The errors in the approximation of a curved surface with rectangular cells produced the instability of MHD unstable plasma. However, this error is not very serious problem for the simulation of stable plasma. (Kato, T.)