Turbulence Diagnostics Using Microwave Imaging Reflectometry in LHD

首次在大型螺旋装置（LHD）中开发了三维微波成像反射仪（MIR），以显示由于密度波动引起的反射面波动。等离子体被对应于4个径向位置的4个频率的探测波照射，成像光学元件将截断面成像到二维喇叭天线混频器阵列（HMA）上。应用该系统观测了边缘谐振振荡（EHO），观察到沿场线的窄结构。3D MIR有望成为研究湍流和约束最强大的诊断仪之一。

Three dimensional (3D) microwave imaging reflectometry (MIR) has been developed in the large helical device (LHD) to visualize fluctuating reflection surface due to the density fluctuation in the first time. The plasma is illuminated by the probe wave with 4 frequencies, which correspond to 4 radial positions, and the imaging optics makes the image of cut-off surface onto the 2D horn antenna mixer arrays (HMA). This system is applied to observe the edge harmonic oscillation (EHO), and a narrow structure along field lines is observed. The 3D MIR is expected to be one of the most powerful diagnostics to study turbulence and confinement.