Two-Dimensional Tomographic Imaging of FRC Merging Process Using Wide-View Visible-Light Tomographic Camera*

The collisional merging experiments of Field-Reversed Configuration (FRC) have been conducted on the FAT-CM device. Two FRC-like initial plasmoids are formed in two conical theta-pinch formation sections which are connected to the central confinement chamber. They are translated by magnetic pressure gradient to collide and merge into a single FRC. A compact and component-based tomographic camera (T-cam) system was developed to visualize the internal structure of FRCs through bremsstrahlung radiation in the visible light range from plasmas. A set of two cameras was attached to the confinement chamber. It successfully reconstructed the internal structure and determined the center of gravity during the translation process of initial plasmoids using the Fourier–Bessel expansion technique. However, it was impossible to do so during and after the collisional merging process due to its narrower observable range compared to the emission area of plasma. The observable range of the wide-view T-cam was designed to enable it to cover most of the area within the confinement chamber. This advancement is expected to enable the reconstruction of the collisional merging process and the subsequent state. This work reports insights from the result of two-dimensional tomographic reconstructions made using the wide-view T-cam.