A reflectometer for fluctuation and correlation studies on the Joint European Torus tokamak

An integrated system of correlation reflectometers have been installed on t he Joint European Torus tokamak. The diagnostic consists of three X-mode, h eterodyne, dual-antenna (bistatic), correlation reflectometers. Two of the reflectometers are dual channel systems at fixed frequencies of 75 GHz (edg e measurements) and 105 GHz (core measurements) with a selectable poloidal (25 mm) or toroidal (40 mm) antenna separation. The third reflectometer is a two frequency system for radial measurements with one channel fixed at 92 GHz and the other swept between 92 and 96 GHz. All three reflectometers op erate simultaneously through the same antenna cluster. The diagnostic can p rovide unique information on the spatial and temporal characteristics of pl asma fluctuations. The capabilities of the system are illustrated with a se lection of results. (C) 1999 American Institute of Physics. [S0034-6748(99) 00510-9].