Relativistic analysis of upper hybrid wave propagation and trapping

We investigate the impact of relativistic effects on upper hybrid (UH) waves in plasmas with thermal electrons, particularly focusing modifications conditions under which UH wave trapping and related low-threshold parametric decay instabilities (PDIs) may occur. A moderately (MR) dispersion relation for waves, valid electron temperatures up to 25 keV frequencies twice cyclotron frequency, is obtained from previous results shown reduce warm non-relativistic result commonly used PDI studies at low temperatures. The MR propagate are then determined compared cold plasma theory, showing a general increase density background magnetic field strength resonance occurs finite next corrections possibility X-mode heated (ECRH) ASDEX Upgrade tokamak scaled versions parameters core resembling those expected ITER ECRH plasmas. virtually unchanged relative due temperatures, while potentially important differences between theory exist ITER-like temperatures; found be insufficient both cases. Finally, qualitatively reproduce thresholds previously studied