Some problems due to spatial instability of a ring current in a plasma

Problems are considered associated with the stability of a ring current in plasma in respect to slow changes during which equilibrium values of the plasma temperature and density are attained. The effect of an iron core inserted inside the tore on the stability of a ring current in plasma is investigated. The maximum temperature of plasma, particularly at shifted equilibrium state may be increased by insertion of an iron core. Problems of repellent force compensation in plasma by an external magnetic field are considered. It is shown that, using variation in the plasma parameters with a current, it is possible to obtain a dynamically stable current-carrying loop inside the plasma (without exerting pressure on the tore wall) by means of an external magnetic field at a certain selection of the law for the field variation