Active control of internal transport barrier formation due to off-axis electron-cyclotron heating in GAMMA 10 experiments
- Plasma Research Centre, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)
The controlled formation of an internal transport barrier (ITB) is observed in GAMMA 10 [T. Cho et al., Nucl. Fusion 45, 1650 (2005)]. The barrier is localized within a layer of a strongly sheared E{sub r}xB plasma rotation (5.5<r{sub c}{<=}10 cm). This high-vorticity layer is formed and maintained by off-axis electron-cyclotron heating, which generates a cylindrical layer (4<r{sub c}<7 cm) with a high-energy electron population that modifies the initial Gaussian radial potential profile into a nonmonotonic one with a hump structure. The local gradients of T{sub i} and T{sub e} are appreciably enhanced in the ITB layer, similarly to those of the ITB in tokamaks and stellarators. Reductions in the effective ion and electron thermal diffusivities are obtained in the barrier layer. A reduction of the observed low-frequency turbulence in the ITB layer and a partial decoupling of the turbulent structures localized on either side of the layer are demonstrated by two-dimensional x-ray diagnostics.
- OSTI ID:
- 21120375
- Journal Information:
- Physics of Plasmas, Vol. 15, Issue 5; Other Information: DOI: 10.1063/1.2906262; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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