Aachen PK 2003 – scientific programme
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P: Plasmaphysik
P 8: Magnetic Confinement
P 8.5: Talk
Tuesday, March 18, 2003, 16:50–17:10, FO2
E × B Velocity Measurements from Doppler Reflectometry — •Jasmine Schirmer, G.D. Conway, W. Suttrop, S. Klenge, H. Zohm, and ASDEX Upgrade Team — Max Planck Institute for Plasma Physics, Boltzmannstr. 2, D-85748 Garching
Doppler reflectometry is a powerful non-invasive measurement technique for studying plasma density fluctuations (i.e. turbulence) with high temporal and spatial resolution. This diagnostic, akin to Radar, works by reflecting a microwave beam off the plasma at a finite tilt angle. The tilt induces a Doppler shift in the returning microwave beam from which the perpendicular propagation velocity (v⊥) of the perturbations is obtained. By varying the tilt angle, different plasma density fluctuation wavelengths are selected and thus a spectrum of the turbulence is measured. The perturbation amplitude can also be obtained from the signal intensity. A radial profile of v⊥ is measured by varying the microwave launch frequency. Generally v⊥ is dominated by the E × B velocity (i.e. the intrinsic perturbation phase velocity is small) and hence the radial electric field (Er) profile can be obtained. vE × B profile measurements will be presented from various plasma confinement scenarios, such as L-mode and H-mode, with forward and reversed magnetic fields.