Particle balance and heat balance in JT-60U

Abstract

Profiles of the ion saturation current ( I s + and the electron temperature ( T e ) on the divertor plates are measured by the use of a poloidal Langmuir probe array in JT-60U hydrogen ohmic discharges. Total particle and heat fluxes to the divertor plates are calculated by integrating the components of I s + and I s + T e perpendicular to the divertor plate. The results are presented in relation to the main plasma parameters such as ¯n e , B t , and the distance of X-point from the divertor plates. The particle flux and ionized neutral influx, which is deduced from the H α emission signals from the plasma boundary, are in fairly good agreement, within experimental errors. The particle confinement time, τ P SOL , including SOL effects is derived from the measured influx, and it decreases with ¯n e in the relatively high density regime ( ¯n e ≥1.3×10 19 m −3 ). However, the deterioration depends on the direction of B t . The power balance between the heat flux and radiated power is discussed.