Return To: Session EXP4 - Current Drive, Heating, Fuelling, Divertors
Prev Page: (EXP4/30) Ion Bernstein Wave Heating Experiments in HT-7
Next Page: Session EXP5 - Transport

(EXP4/31) Mechanism of H-mode Triggering by CT Injection in the STOR-M Tokamak

C. Xiao¹⁾, D. R. McColl¹⁾, A. Hirose¹⁾, S. Sen^2)
 
1) Plasma Physics Laboratory, University of Saskatchewan, Saskatoon, Canada
²⁾ School of Mathematical and Computational Sciences, University of St. Andrews, UK; also at Centre of Plasma Physics, Sapta Swahid Path, India

Abstract.  The H-mode like discharges induced by tangential compact torus (CT) injection in the STOR-M tokamak and by other techniques, such as by a short current pulse and electrode/limiter biasing, are commonly characterized by an increase in the electron density, significant reduction in the H_$\alpha$ radiation level, and steepening of the edge density profile. The H-modes induced by negative biasing and edge heating via a short current pulse result in large negative electric potential biasing, formation of a strong poloidal velocity shear, and slowdown of the toroidal flow. In contrast, in the H-modes induced by positive biasing and CT injection, only moderate positive electric potential biasing occurs. Formation of a strong poloidal velocity shear is absent, but the toroidal flow velocity increases. A plausible mechanism that does not require strong velocity shear itself to suppress the long wavelength turbulence is attributed to the stabilizing role of the curvature in the toroidal velocity profile.

Read the full paper in PDF format.