Author/Authors :
Sharma، نويسنده , , S.K. and Zushi، نويسنده , , H. and Takagi، نويسنده , , I. and Hisano، نويسنده , , Y. and Shikama، نويسنده , , T. and Morita، نويسنده , , S. and Tanabe، نويسنده , , T. and Yoshida، نويسنده , , N. and Sakamoto، نويسنده , , M. and Higashizono، نويسنده , , Y. and Hanada، نويسنده , , K. and Hasegawa، نويسنده , , M. and Nakamura، نويسنده , , K. and Idei، نويسنده , , H. and Sato، نويسنده , , K.N. and Kawasaki، نويسنده , , S. and Nakashima، نويسنده , , H. and Higashijima، نويسنده , , A. and Nakashima، نويسنده , , Y. and Hatano، نويسنده , , Y. and Sagara، نويسنده , , A. and Nakamura، نويسنده , , Y. and Ashikawa، نويسنده , , N. and Maekawa، نويسنده , , T. and Kishimoto، نويسنده , , Y. and Takase، نويسنده , , Y.، نويسنده ,
Abstract :
In order to investigate the overall atomic hydrogen background and the dynamic characteristics of wall pumping/fuelling phenomenon, a permeation probe system has been developed and applied in the spherical tokamak QUEST. Reliability of measurements, within ±3% accuracy and a positive correlation with the hydrogen line emission over three orders of magnitude have been demonstrated for more than 3000 various plasma discharges. By comparison of the experimental permeation (flux) curves with the numerically simulated curves, the net incident atomic hydrogen flux is evaluated in the range of 1 × 1019 H m−2 s−1 to 4 × 1020 H m−2 s−1. The atomic flux has been investigated as a function of various plasma operation parameters like RF power, gas pressure and magnetic configuration. Using the static particle balance and permeation measurements, the progress in wall conditioning has been investigated. An inverse correlation between the atomic hydrogen flux and improvement in wall pumping has been observed over the two campaigns.
