Carbon influx flow rate in an Ohmically heated plasma in the FM-1 spherator

Abstract

The flow rate of neutral carbon atoms during the initial start-up phase of an Ohmically heated plasma in th e FM-1 spherator was determined from the spatially resolved measurements of the carbon line radiation and independent measurements of spatial distribution of plasma density and electron temperature. This was accomplished by comparing the measured carbon line intensity with a numerical solution of time-dependen t couple d differential rate equations for several carbon ionization states. The differential equations used in the present model correspond to a spatially homogeneous medium. However, th e effects of plasma inhomogeneity were taken into account by calculating the plasma emission at each location using the experimentally measured electron density and temperature (i.e. the measured radial distributions of density and temperature were folded into the numerical calculations). The empirical flow rate of carbon atoms into the discharge. Γflow(t),was found to be Γflow(t)≃ne(t)/τflow. where τflow was 30–100 ms depending upon discharge conditions