Electron density measurements of non-inductive start-up plasmas in the TST-2 spherical tokamak

A new 50GHz microwave interferometer was installed, and non-inductively sustained spherical tokamak plasmas in the TST-2 device were measured. The line integrated electron densities (nels) on five chords were compared with visible CCD camera image and equilibrium analysis. It is concluded that the high-density region has a C-like shape along the outboard boundary. This shape suggests that the electron density is not constant on the magnetic flux surface. c