Doppler Temperature and Particle Confinement Time Determined from Measurements of Hα-Line on a Tokamak Plasma in the JFT-2a Device

Radiation from the H α -line has been investigated in the hydrogen tokamak plasma obtained under a typical JFT-2a discharge. The profiles of the H α -line were measured along both perpendicular and tangential paths to the toroidal magnetic field. The measured profiles can be interpreted in terms of Doppler broadening at the line wings due to hot hydrogen atoms originating from the resonance charge-exchange process and at the line center due to cold particles having energies of a few to several eV. The peak value of the Doppler temperature for the hot particle was approximately 50 eV. Equal temperatures were obtained from measurements along perpendicular and tangential directions to the toroidal magnatic field. Distributions in the minor cross-section of photon numbers of the H α -line were also measured, from which the confinement time of charged particles was found to be 0.5 to 2.5 msec.