Volume Rendering Method Applied to 3D Edge Impurity Emission in LHD to Produce Projection Image in Arbitrary Plane

Abstract

Understanding edge impurity transport is one of the important issues for fusion devices to control edge radiation distribution for detachment operation and impurity influx to the confinement region. In LHD, the edge magnetic field structure becomes complex stochastic magnetic field. In order to study relation between impurity transport and the magnetic field geometry, 3D edge impurity emission distributions are obtained by a multichannel spectrometer system and tomography scheme. However, it is difficult to understand the three-dimensional (3-D) structure. Therefore, we propose a visualization system that employs a volume rendering method. With the proposed system, which can be used on a PC or mobile device, the user can observe a 3D structure in an arbitrary plane. To realize this function, we propose a volume visualization system comprising preprocessing and real-time rendering stages. Therefore, the visualization framerate can exceed 30 frames per second on PCs and approximately six frames per second on mobile devices, although the user frequently changes the position and direction of the camera.