The relationship between the edge toroidal field B t and the rotation of the spatial structure of visible light emitted from reversed field pinch (RFP) plasmas is reported. The rotation of the spatial structure of visible light is captured by a high-speed camera attached to a horizontal viewing port of the RELAX , which was designed for RFP experiments. It is found that the rotation velocity and the direction of the spatial structure of visible light depend on B t . In the non-reversal case, the structure rotates in the co-current direction, while in the countercurrent direction in the reversal case. The frequency and direction of the spatial structure of visible light are consistent with magnetic fluctuations measured by magnetic probes.
A new passive monitoring system applied to large surface wave plasmas (SWP) is experimentally tested. In the first experiment, spatial distributions of the electron density and temperature are measured using double probes. Subsequently, an integral photography with deconvolution techniques is applied to identify the three-dimensional emissivity distribution of SWP. The result obtained from the first experiment seems to identify the localization of SWP around the antenna launching an 860-MHz microwave.
In this study, a previously proposed three-dimensional (3D) tomography method using a multiple-pinhole camera is applied experimentally to detect 3D structures in reversed-field pinch plasmas. The 3D structure of the toroidal plasma was successfully reconstructed and found to be consistent with magnetic field measurements at the plasma's edge. The results also indicate that toroidal mode number estimation may be possible using the images from the multiple-pinhole camera.
In this study, we demonstrated the principle underlying the three-dimensional (3D) reconstruction of plasma structure by using a soft X-ray camera with multiple pinholes. Time evolutions of seven independent soft X-ray images were captured by the camera. The obtained data were used to reconstruct a 3D soft X-ray emission profile in the reversed-field pinch produced in the RELAX machine, which appeared to be consistent with the forecast in our feasibility study. c
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