Density Fluctuation Measurements Using a Frequency Hopping Reflectometer in JT-60U

Naoyuki OYAMA, Hidenobu TAKENAGA, Takahiro SUZUKI, Yoshiteru SAKAMOTO, Akihiko ISAYAMA
2011 Plasma and Fusion Research  
In JT-60U, a frequency hopping reflectometer has been developed to evaluate the poloidal rotation velocity as a Doppler reflectometer and the radial correlation of density fluctuations in plasmas. The system can measure the radial profile of density fluctuations or the radial correlation profile at two spatial points within 250 ms by combining with the other fixed frequency reflectometer. The radial profiles of the poloidal rotation velocity evaluated from the Doppler-shifted frequency spectrum
more » ... of density fluctuations show a positive radial electric field in co-rotating plasmas and a negative radial electric field in counter-rotating plasmas. Density fluctuation measurement at the internal transport barrier (ITB) using a correlation reflectometer revealed that long-range correlation increased when ITB was degraded owing to the central heating by electron cyclotron waves.
doi:10.1585/pfr.6.1402014 fatcat:vhlnrgkzzncknbxb5nkyto7dci