Study of effects of impurity ions and neutral atoms on reversed-field pinch by 2-D MHD pinch simulation

Two-dimensional MHD pinch simulation code, ''TOPICS'', which includes the effects of the impurity ions, the neutral atoms and anomalous resistivity, has been applied to the investigation of the RFP-plasmas at the setting-up phase of the TPE-lR. Simulations are compared with the typical two cases of the experiment: (a) the lower initial bias field and the higher plasma current density and (b) the higher initial bias field and the lower plasma current density. The magnetic field profiles at the setting-up phase in the experiments can be fairly well explained by the simulation assuming the 50% ionization degree of the initial plasma and the presence of 10% oxygen. It is also found from the simulation that the radiation loss due to 5 to 10% impurities is the dominant electron energy loss mechanism. The toroidal magnetic field profile at the setting-up phase calculated by using the isotropic anomalous resistivity is much narrower than that by the classical resistivity. (author)