Spectroscopic Measurement Of Hydrogen Atom Density In A Plasma Produced With 28 Ghz Ech In Quest

The spatial distribution of the hydrogen atom density was evaluated in a spherical tokamak (ST) plasma sustained only with 28 GHz electron cyclotron heating (ECH). The radially resolved H-delta emissivity was measured using multiple viewing chord spectroscopy and Abel inversion. A collisional-radiative (CR) model analysis of the emissivity resulted in a ground-state hydrogen atom density of 10(15)-10(16) m(-3) and an ionization degree of 1-0.85 in the plasma.