[Table of Contents]

Plasma and Fusion Research

Volume 6, 1402014 (2011)

Regular Articles


Density Fluctuation Measurements Using a Frequency Hopping Reflectometer in JT-60U
Naoyuki OYAMA, Hidenobu TAKENAGA, Takahiro SUZUKI, Yoshiteru SAKAMOTO, Akihiko ISAYAMA and the JT-60 Team
Japan Atomic Energy Agency, 801-1 Muko-yama, Naka, Ibaraki 311-0193, Japan
(Received 24 December 2010 / Accepted 11 February 2011 / Published 18 March 2011)

Abstract

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 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.


Keywords

reflectometer, density fluctuation, radial correlation length, radial electric field, plasma rotation

DOI: 10.1585/pfr.6.1402014


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This paper may be cited as follows:

Naoyuki OYAMA, Hidenobu TAKENAGA, Takahiro SUZUKI, Yoshiteru SAKAMOTO, Akihiko ISAYAMA and the JT-60 Team, Plasma Fusion Res. 6, 1402014 (2011).