Physics basis for an advanced physics and advanced technology tokamak power plant configuration: ARIES-ACT1

The advanced physics and advanced technology tokamak power plant ARIES-ACT1 has a major radius of 6.25 m at an aspect ratio of 4.0, toroidal field of 6.0 T, strong shaping with elongation of 2.2, and triangularity of 0.63. The broadest pressure cases reached wall-stabilized β_N ∼ 5.75, limited by n = 3 external kink mode requiring a conducting shell at b/a = 0.3, requiring plasma rotation, feedback, and/or kinetic stabilization. The medium pressure peaking case reaches β_N = 5.28 with B_T = 6.75, while the peaked pressure case reaches β_N < 5.15. Fast particle magnetohydrodynamic stability shows that the alpha particles are unstable, but this leads to redistribution to larger minor radius rather than loss from the plasma. Edge and divertor plasma modeling shows that 75% of the power to the divertor can be radiated with an ITER-like divertor geometry, while >95% can be radiated in a stable detached mode with an orthogonal target and wide slot geometry. The bootstrap current fraction is 91% with a q₉₅ of 4.5, requiring ∼1.1 MA of external current drive. This current is supplied with 5 MW of ion cyclotron radio frequency/fast wave and 40 MW of lower hybrid current drive. Electron cyclotron is most effective for safety factor control over ρ∼0.2 to 0.6 with 20 MW. The pedestal density is ∼0.9× 10²⁰/m³, and the temperature is ∼4.4 keV. The H₉₈ factor is 1.65, n/n_Gr = 1.0, and the ratio of net power to threshold power is 2.8 to 3.0 in the flattop.