Motional Stark effect plasma equilibria during LHCD experiments on PBX‐M

The magnetic field pitch angle measurements from the multichannel Motional Stark Effect (MSE) polarimeter system, together with the external poloidal flux values, toroidal plasma current, coil currents, and plasma pressure profile, as computed by the TRANSP code, are used to constrain the numerical solution of the Grad‐Shafranov equation. The experimental results from the soft x‐ray diagnostic and hard x‐ray bremsstrahlung radiation profiles show clear signatures of a change in the current density profile during Lower hybrid injection. Indications of a variation in the q‐profile are supported by the behavior of the measured sawtooth inversion radius. Modifications in the current density profiles, induced by Lower Hybrid waves, are discussed in terms of their effect on q‐profiles and volume‐averaged quantities like Ii.