Turbulence reduction and poloidal shear steepening in reversed shear plasmas on Tore Supra
Infra-red light scattering is used to characterize turbulence during reversed shear scenario obtained by a fast current ramp-up on Tore Supra. The preformed hollow profile is feted using ion cyclotron resonance frequency minority heating (ICRH). Turbulence intensity is recorded to dramatically decrease during the ramp-up and to recover smoothly as the discharge is ended. The core reduction, deduced from the light scattering measurements, is confirmed by the effective heat diffusivity behaviour. Turbulence reduction is hown to occur simultaneously with the steepening of the radial electric field shear, deduced from the frequency spectra, as well as with the negative or flat magnetic shear. In consequence, a confinement improvement of about 40% is achieved for about 2 seconds
Bibliographic Reference: Report: EUR-CEA-FC-1684 (1999), 15pp.
Availability: Available from the Librarian CEA Cadarache (FR)
Record Number: 199911756 / Last updated on: 2000-01-30
Original language: en
Available languages: en