Synchrotron radiation and its relevance on plasma diagnostics in next generation tokamaks

Plasma diagnostics using synchrotron radiation in next generation large tokamaks is discussed. Is is first shown that for electron temperature on axis in excess of 20--25 keV, harmonic overlap invalidates the familiar second harmonic emission method for temperature measurements in the central plasma region. Next, it is shown that radiation measurements at arbitrary frequencies of the X-mode normal to the magnetic field in the horizontal and vertical directions yield a set of independent equations for deriving the plasma parameters characterizing the temperature and density profiles. The method and the salient features of the emitted radiation at arbitrary frequencies are illustrated for parameters being considered in the design of tokamak reactors