Formation and Sustainment of a Spheromak with BiasFlux by DC Helicity Injection

The formation and sustainment of a spheromak plasma with bias flux has been demonstrated successfully by “DC” or “electrostatic” helicity injection. The experimental results show that, as the helicity injection rate is increased, the self-generated toroidal plasma current and the toroidal flux increase significantly. By examination of the contours of poloidal flux of the sustained spheromak, we have verified the formation of the magnetic configuration with the external bias flux linking the region of the closed flux surfaces. In addition, it has been found that the λ spk ≡ j // / B value of the sustained spheromak configurations with a small amount of the closed flux in the flux conserver has been affected by the ratio of the electrode current to the bias flux.