Electron internal transport barriers, rationals and quasi-coherent oscillations in the stellarator TJ-II

The evolution of core quasi-coherent modes has been investigated during the formation of electron internal transport barriers (e-ITB) in the TJ-II stellarator. These modes have been characterized using heavy ion beam probe and electron cyclotron emission diagnostics. The quasi-coherent mode evolves during formation/annihilation of the e-ITB and vanishes as the transport barrier is fully developed. These observations can be interpreted in terms of the influence of sheared flows in the stability of quasi-coherent modes.

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