X-ray tomography systems for observations of electron cyclotron heated plasmas using novel position-sensitive X-ray semiconductor-detector arrays

Tomographic reconstructions of X-ray emission from hot electrons having a temperature of several tens of keV and cold electrons having a temperature ranging below 100 eV have been carried out by the use of the novel position-sensitive X-ray diagnostic system. The X-ray detection system in the thermal-barrier region of the GAMMA 10 tandem-mirror plasmas consists of a 48-channel silicon semiconductor detector array and the 50-channel microchannel plates (MCPs). When we make outward shifts of the second-harmonic electron cyclotron layers radially by intensifying the mirror magnetic fields in the thermal-barrier region, tomographically reconstructed signals by using the MCP show hollow X-ray profiles and the X-ray reconstructed signals obtained with the semicondcutor detector indicate a good axisymmetric radial profile peaked on the magnetic axis. Several applications including investigation of these hot electrons due to the second-harmonic electron cyclotron heating are made with the newly developed X-ray diagnostic systems.