Reflectometer fluctuation and correlation studies on Jet
Three X-mode, heterodyne, dual-channel correlation reflectometers (75 GHz, polidal/toroidal : 105 GHz poloidal/toroidal : 92 GHz - 96 GHz swept, radial) operating on the Joint European Torus (JET) tokamak are described, together with recent results. A range of fluctuation phenomena (edge-localized modes (ELM), coherent magnetohydrodynamic (MHD) modes, etc) are observed, as well as variations in core and edge turbulence during ohmic, L-mode and H-mode plasmas. Radial correlation lengths are generally less than 5 mm for turbulence but rise to 1 cm or more for coherent modes. Toroidal correlation lengths range from 5 cm to 10 cm. Large changes in toroidal rotation velocities are also observed (few km per second with interrupted continuous radio frequency (ICRF), tens of km per second with neutral beam heating). Signal imbalances between channels - particularly in low axis and high triangularity discharges, are explained in terms of asymmetries in alignment of the antennas.
Bibliographic Reference: Report: JET-P (97) 13 EN (1997) 11pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon OX14 3EA (GB)
Record Number: 199711266 / Last updated on: 1997-10-10
Original language: en
Available languages: en