Plasma heating with strong poloidal Ohmic currents

The feasibility of using strong poloidal currents to heat plasmas has been examined experimentally in Tokapole II, operating as a toroidal octupole. The plasma resistivity ranges from that of Spitzer to about 1500 times Spitzer resistivity, as predicted by mirror‐enhanced resistivity theory. This allows large powers (approximately 2 MW) to be coupled to the plasma at modest current levels. However, the confinement time is reduced by the heating, apparently due to a combination of the input power location (near the walls of the vacuum tank) and fluctuation‐enhanced transport.