Measurements of Balmer H sub(α)-line emitted from tokamak plasmas in JFT-2a device

Visible radiation of Balmer H sub(α)-line has been spectroscopically investigated on hydrogen tokamak plasmas in JFT-2a device with toroidal magnetic field 10 kG, plasma current 15 kA and ratio of divertor to plasma currents 1.1. The profiles of H sub(α)-line were measured on the equatorial plane horizontally along both perpendicular and tangential paths to the toroidal magnetic field, and vertically along different three paths in the minor cross-section. The typical measured profiles are interpreted in terms of the doppler broadening at line wings due to high-temperature hydrogen atoms originating through the resonance charge-exchange process and the doppler broadening at the line center due to low-temperature particles corresponding to Franck-Condon neutrals from dissociation of molecular hydrogen neutrals or ions. The peak value of doppler temperature for the hot particles is approximately 50 eV, and temperature of the cold neutrals is a few--several eV. It is noticed that equal temperatures are obtained in measurements along perpendicular and tangential directions to the toroidal magnetic field. Distributions in the minor cross-section of photon numbers of H sub(α)-line are measured, from which the confinement time of charged particles is determined to be 0.5--2.5 msec. (auth.)