Microwave imaging reflectometry in LHD

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

Three-dimensional (3D) microwave imaging reflectometry has been developed in the large helical device to visualize fluctuating reflection surface which is caused by the density fluctuations. The plasma is illuminated by the probe wave with four frequencies, which correspond to four radial positions. The imaging optics makes the image of cut-off surface onto the 2D (7 × 7 channels) horn antenna ...

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...

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...

Microwave Imaging Using SAR

Polarimetric Synthetic Aperture Radar (Pol.-SAR) allows us to implement the recognition and classification of radar targets. This article investigates the arrangement of scatterers by SAR data and proposes a new Look-up Table of Region (LTR). This look-up table is based on the combination of (entropy H/Anisotropy A) and (Anisotropy A/scattering mechanism α), which has not been reported up now. ...

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