Improved Core Elwctron Energy Confinement in TCV Tokaman Plasmas with Central EC Counter Current Drive
A quasi stationary regime of improved core electron energy confinement (ICEC) has been identified in the TCV tokamak. It has been obtained under conditions of dominant electron heating using cyclotron waves at the second harmonic (82.3GHz for TCV) and is characterized by core electron temperatures near and above 10 keV and global electron energy confinement times 3 to 4 times higher than those predicted by the RLW scaling law. The heating scenario comprises two phases separated by a time delay of about 300ms : a so-called pre-heating phase with off-axis power deposition and a high performance phase during which additional power is injected into the centre in counter current drive (CNTR-ECCD) orientation with a toroidal component of the beam launching angle of about 30 degrees. For the experiments described here, power levels of 0.9 to 1.3SMW were used for preheating at a normalized radius of p -0.3, whereas up to 0.9MW were injected for central counter ECCD. The target plasma, in limiter configuration, is described by the following parameters: <ne> = 1.5 10(19) m(-3), Ip = 200kA, k ~ 1.7, q(a) >/- 7.
Bibliographic Reference: An oral report given at: The 28th EPS Conference of Controlled Fusion and Plasma Physics. Held in: Madeira (PT) June 2001
Record Number: 200013689 / Last updated on: 2001-09-18
Original language: en
Available languages: en