A Proof of Principle of Imposed Dynamo Current Drive: Demonstration of Sufficient Confinement

The conceptual design of an experiment for demonstrating and developing the efficient sustainment of a spheromak with sufficient confinement is presented. “Sufficient” means that the current drive power can heat the plasma to its stability β limit. Previous transient experiments showing sufficient confinement in the kilo-electron-volt temperature range with no external toroidal field coil, recent results on Helicity Injected Torus with Steady Inductive (HIT-SI) showing sustainment with sufficient confinement, the potential of imposed dynamo current drive (IDCD) of solving other fusion issues, and a very attractive reactor concept justify a proof-of-principle experiment for a high-β spheromak sustained by IDCD. A machine with 1-m minor radius with the required density control, wall loading, and neutral shielding for a 10-s pulse is described. Peak temperatures of 3 keV and toroidal currents of 3.2 MA and 16% wall-normalized plasma β are envisioned.