Electron cyclotron current drive experiments on T-10

Abstract

The results of electron cyclotron current drive experiments on the T-10 tokamak are presented.The total RF power was up to 2.5 MW, the electron temperature was up to 7 keV and the maximum driven current was 110 kA. The current drive efficiency qcD was approximately 0.1 A/W. The value of qcD and its dependence on the plasma parameters agree satisfactorily with the linear theory, corrected for the finite confinement time of resonant electrons. In discharges with large beta poloidal, ,9, = 3, complete replacement of the inductive current by non-inductive electron cyclotron current drive and bootstrap current was obtained.

Diagnostic techniques for measuring suprathermal electron dynamics in plasmas (invited)

“…Because of the different regions of phase space with which ECH interacts, simulations show that the accelerated electrons remain generally more collisional than in the case of LHCD, resulting in weaker HXR emission. This was confirmed in early measurements, which also showed that more suprathermal emission is observed in the case of ECCD, 43,44 which targets electrons with high parallel velocity, than with pure ECH. These measurements, particularly on the T −10 tokamak, were used to study the decay time upon power switch-off, 43 again concluding that cross-field transport was negligible.…”

“…This was confirmed in early measurements, which also showed that more suprathermal emission is observed in the case of ECCD, 43,44 which targets electrons with high parallel velocity, than with pure ECH. These measurements, particularly on the T −10 tokamak, were used to study the decay time upon power switch-off, 43 again concluding that cross-field transport was negligible. 59 This conclusion was challenged when measurements were performed with ECCD on TCV, which features extremely high ͑up to 40 MW/ m 3 ͒ ECH power densities.…”

“…These types of detectors have been employed in a variety of laboratory experiments. 17,[43][44][45][46] Both Ge and Si detectors have been featured prominently in spacecraft instrumentation, particularly in observations of HXR emitted from the solar corona by flares and coronal mass ejections. 47 More recent is the development of CdTe and CdZnTe ͑CZT͒ crystals as room-temperature HXR detectors.…”

Using High-Power Gyrotrons in the T-10 Tokamak

“…However, as a result of studying the energy keeping during variation in the plasma parameters in a wide range of their values when introducing an additional microwave radiation, it was shown that the energy lifetime τ E significantly decreases with increasing introduced radiation power P : τ E ∝ P −0. 6 . The results of the study of the transport coefficients during the ECR plasma heating are reviewed in [4].…”

“…For this purpose, the further plasma-heating experiments in the T-10 tokamak were conducted using the second ECR harmonic. In this case, the waves had extraordinary polarization, i.e., the X mode was used [5]. In the above-mentioned experiments, the gyrotrons with the frequency f = 140 GHz, power P HF ≈ 0.5 MW, and a microwave-pulse duration of up to 400 ms were used.…”