Low noise Kα-band hopping reflectometer based on yttrium iron garnet sources at TEXTOR.

The heterodyne hopping reflectometer system based on wide-tuned low noise yttrium iron garnet sources was developed for TEXTOR experiment. Being installed in 1998 it successfully operates more than 10 years providing the measurements of plasma density fluctuations. Owing to the advance multihorn antennae systems installed at three different positions around the tokamak, the correlation properties as well as the propagation measurements of plasma density fluctuations are realized. The reflectometer operates in ordinary polarization mode providing the access mostly to plasma gradient and pedestal region. The capabilities of the diagnostic are illustrated with the examples of measured fluctuation characteristics in the variety of TEXTOR plasmas.