Tomographic reconstructions of xhyphen;ray emission from hot electrons have been carried out in the thermal barrier region of the GAMMA 10 plasmas. Here, the first application of two sets of the 50hyphen;channel microchannel plates have been performed using their detailed calibration data as a function of xhyphen;ray energy and incident angle lsqb;Rev. Sci. Instrum.59, 256 (1988);59, 2453 (1988);60, 368 (1989)rsqb;. The xhyphen;ray reconstructed signals under standard thermal barrier operating conditions indicate a good axisymmetric radial profile peaked on the magnetic axis. This symmetric profile is important for preventing the formation of a local anisotropic electric field, which may cause particle confinement degradation, and its peaking profile is desirable for thermal barrier potential formation in the core plasma region. When we have relocated the secondhyphen;harmonic electron cyclotron layers (ohgr;=2OHgr;e) in two different ways (moving them out radially, or axially away from the midplane), tomographic reconstructions show hollow xhyphen;ray profiles in both cases. These may be formed due to theEtimes;Brotations of the hot electrons produced near ohgr;=2OHgr;e. These applications of xhyphen;ray tomography to twohyphen;dimensional radial profile observations along with the axial xhyphen;ray profile measurement give information that the production mechanism of these hot electrons is ascribed to secondhyphen;harmonic electron cyclotron heating.
展开▼
