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Good knowledge of the ECH power deposition profile is essential for the experimental study of heated plasmas (energy and particle transport, magnetic confinement stability), for profile tailoring, current drive, as well as for the verification ECH ray tracing codes. In TCV this is complicated by the combination of a large variety of plasma shapes (elongation <2.56, -0.7 <triangularity <+0.5, to date) and a versatile ECH launching system (ultimately 9 beams, 6 at the second harmonic with independent poloidal and toroidal launching angles and 3 at the third harmonic with independent poloidal launching angles). The dynamic response to ECH power perturbations of the electron temperature inferred from soft X-ray emissivity and diamagnetic measurements is used here to examine the ECH deposition. The deposition can be examined with different modulation waveforms: sinusoidal at high frequencies (70Hz to 500Hz) to diminish the effect of transport; random binary signal (RBS) to diminish the effect of coupling with the sawteeth; the response at power turn on and off. The pollution of the X-ray response from the component due to the sawtooth instability, which usually makes analysis difficult, has been treated using a Generalized Singular Value Decomposition (GSVD) technique. Study is not restricted to non sawtoothing discharges but covers the whole plasma current capability of TCV.

Additional information

Bibliographic Reference: Article: 26th EPS Conference on Controlled Fusion and Plasma Physics, (1999)
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