Electron Bernstein wave (EBW) assisted plasma current start-up has been demonstrated for the first time in a tokamak. It was shown that plasma currents up to 17 kA can be generated noninductively by 100 kW of RF power injected. With optimized vertical field ramps, plasma currents up to 33 kA have been achieved without the use of solenoid flux. It is shown that the plasma formation and current generation are governed predominantly by EBW current drive. Experimental results are consistent with ray-tracing and quasilinear Fokker-Planck modeling.

Electron-Bernstein waves (EBW) were excited in the plasma by mode converted extraordinary (X) waves launched from the high field side of the COMPASS-D tokamak at different toroidal angles. It has been found experimentally that X-mode injection perpendicular to the magnetic field provides maximum heating efficiency. Noninductive currents of up to 100 kA were found to be driven by the EBW mode with countercurrent drive. These results are consistent with ray tracing and quasilinear Fokker-Planck simulations.

The existing Globus-M machine [1] is a low aspect ratio compact tokamak (R = 0.36 m, a = 0.24 m) with high specific ohmic and auxiliary heating power. First plasma was achieved in Globus-M in 1999. The machine has demonstrated practically all of the project objectives ever since. Target design parameters (aspect ratio-1.5, 2 − X-point configuration, vertical elongation-2.2, traiangularity-0.45, average density-1.0•10 20 m −3 , plasma current-0.3 MA, toroidal beta-12%, auxiliary heating power-1 MW) [2] were achieved and some of them overcame [3,4]. Also Globus-M

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On MAST studies of the profile evolution of the electron temperature (Te), electron density (ne), radial electric field (Er) as well as novel measurements of the ion temperature (Ti) and toroidal current density (jϕ) in the pedestal region allow further insight into the processes forming and defining the pedestal such as the H-mode access conditions and MHD stability. This includes studies of fast evolution of Te, ne and Er with Δt = 0.2 ms time resolution and the evolution of pe and jϕ through an edge-localized mode (ELM) cycle. Measurements of the H-mode power threshold, PL−H revealed that about 40% more power is required to access H-mode in 4He than in D and that a change in the Z-position of the X-point can change PL−H significantly in single and double null configurations. The profile measurements in the L-mode phase prior to H-mode suggest that neither the gradient nor the value of the mean Te or Er at the plasma edge play a major role in triggering the L–H transition. After the transitions, first the fluctuations are suppressed, then the Er shear layer and the ne pedestal develops followed by the Te pedestal. In the banana regime at low collisionality (ν⋆) ∇Ti ≈ 0 leading to Ti > Te in the pedestal region with Ti ∼ 0.3 keV close to the separatrix. A clear correlation of ∇Ti with ν⋆ is observed. The measured jϕ (using the motional Stark effect) Te and ne are in broad agreement with the common peeling–ballooning stability picture for ELMs and neoclassical calculations of the bootstrap current. The jϕ and ∇pe evolution Δt ≈ 2 ms as well as profiles in discharges with counter current neutral beam injection raise questions with respect to this edge stability picture.