Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta

摘要

Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-tomagnetic pressure ratio (beta(t)), low internal inductance, high elongation, and nonsolenoidal current drive is a central goal of present tokamak plasma research. Stable access to this desirable parameter space is demonstrated in plasmas with ultralow aspect ratio and high elongation. Local helicity injection provides nonsolenoidal sustainment, low internal inductance, and ion heating. Equilibrium analyses indicate beta(t) up to similar to 100% with a minimum vertical bar B vertical bar well spanning up to similar to 50% of the plasma volume.