Synchrotron emission from the relativistic ring electrons in the ELMO Bumpy Torus

The energy spectrum of the synchrotron radiation emitted by the relativistic ring electrons in ELMO Bumpy Torus (EBT) has been calculated for various classes of isotropic and anisotropic ring electron distribution functions. Calculations have been carried out for present (EBT-I/S) and planned (EBT-P) experiments. The ring temperatures in EBT-I and EBT-S are approximately 200 and 500 keV, respectively. The projected ring temperature in EBT-P is about 1000–1500 keV. The calculations indicate that the radiation is predominantly in higher harmonics (l≥γ2/2) and the radiation spectrum monotonically decreases and becomes almost flat at high frequencies, as observed in the experiments. With increasing temperature or anisotropy ratio (T⊥/T∥), the total emission increases, the slope of the spectrum at ω≫ωc decreases, and the peak of the spectrum moves to higher frequency. The ratio of the extraordinary wave intensity to ordinary wave intensity decreases with temperature but increases with anisotropy ratio. Calculated spectra and relative intensity levels of EBT-I and EBT-S are found to be in reasonable agreement with the experimental measurements. Both measurements and calculations show that synchrotron losses are low in EBT-I and EBT-S. However, in future experiments (EBT-P, reactor, etc.), radiation losses will play an important role in determining the ring power balance. Correlations of calculated intensity variations with temperature, density, beta, anisotropy ratio, etc., are given that can be used as a useful tool for comparison of theory and experiment, as well as in the determination of ring properties and scaling of the radiation with ring parameters.