Development of 3D microwave imaging reflectometry in LHD (invited).

An Ultrashort-Pulse Reflectometry for LHD Plasmas

We have applied an ultrashort-pulse reflectometer (USRM) to large helical device (LHD) plasmas for density profile measurement. This system can be controlled and monitored from remote site (Kyushu University) by using ultra wideband science information network (super-SINET) that ideal bandwidth reaches up to 1 Gbps. As a result of the measurement, we have confirmed reflection wave from the plas...

Investigation of turbulence in reversed field pinch plasma by using microwave imaging reflectometry

Plasma curvature effects on microwave reflectometry fluctuation measurements

Plasma poloidal curvature can significantly extend microwave reflectometry responses to high k⊥ poloidal fluctuations. Reflectometry responses can be several orders of magnitude larger at high k⊥ than that predicted by analysis based on two dimensional (2-D) slab geometry. As a result, the responses may approach the 1-D geometrical optics limit. This super resolution leads to a major modificati...

Reconstruction method of X-mode ultrashort-pulse reflectometry in LHD

Reflectometry is considered to be one of the key diagnostics to measure density profiles and density fluctuations of fusion oriented plasmas. When an electromagnetic wave is launched into a plasma, the wave is reflected at the corresponding cutoff layer of the ordinary (O) mode or the extraordinary (X) mode. Reflectometry measures the time of flight (TOF) or group delay of the reflected wave. W...

Radial Interaction in Dynamic Heat Transport of LHD Plasmas

The radial interaction of heat transport is clarified by cross-correlation between electron heat flux and electron temperature gradient in LHD. Correlations between the heat transport dynamics and the radial structures of turbulence are also investigated. The existence of a turbulence modulator is discerned by using the conventional reflectometry signals. The amplitude of high frequency (> 100k...