Princeton Large Tokamak Scaling Laws for Thermonuclear Fusion Power Multiplication

While present experiments are evaluated on the basis of confinement time, it is the fusion power multiplication factor, Q, and the fusion power that will be the parameters measuring the performance of ignition experiments and fusion reactors. We have determined the relationship of Q to τ_E and the Lawson number, nτ_E, for ohmically heated plasmas from the Princeton large tokamak (PLT). The values Q, τ_E, and nτ_E all increase with density at low densities. Above _e ≃ 4 × 10¹³ cm⁻³, τ_Ee ≃ 30 ms, or _eτ_Ee ≃ 1.2 × 10¹² cm⁻³s, Q saturates; Q scaling has also been obtained on PLT as a function of toroidal magnetic field, plasma current, and auxiliary heating power.