Startup and Quasistationary Drive of Plasma Current by Lower Hybrid Waves in a Tokamak

A plasma current is initiated and raised to a quasistationary level of about 20 kA by injection of the lower hybrid wave into a cold and low-density plasma produced by electron cyclotron resonance. The plasma current rises more slowly than the experimentally obtained LₚRₚ magnetic diffusion time of the bulk plasma. The current rise time is inversely proportional to the bulk electron density, and agrees well with the collision time of the current-carrying high-energy electrons with the bulk plasma.