Model Experiment on Quasi-Stationary Vertical Magnetic Field in a Tokamak Type Apparatus

An experiment with a model device of the JIPP T-II apparatus, a hybrid apparatus between Tokamak and Stellarator, is carried out in order to investigate various factors altering the decay index due to the current of a winding for the D.C. vertical magnetic field (designed index). The image current in an iron core of the current of the winding makes worse the designed index. However, the added contribution of a primary current, its image, and the image of a plasma current in the iron core alters the designed index favorably. The effect of the excitation of the iron core is negligible. The distribution of the resultant decay index in the real apparatus is expected to be improved satisfactorily by the added contribution.