ELECTROSTATIC WAVE INSTABILITY AND PLASMA RADIATION FROM CORONAL LOOPS

Polarization properties of solar and stellar radio emission require. i n some cases, emission below the third or fourth coronal electron gyro level, omega < 3 omega(c);4 omega(c). In the context of plasma radiat ion, the source parameters should be such that the 'intermediate magne tic field condition' 1 < omega(p)(2) / w(c)(2) < 3 is satisfied. Suppo sing this condition, we investigate the generation of electrostatic wa ves in a 'warm' background plasma with a high-energy component of magn etically trapped electrons. We invoke the conversion of upper-hybrid w aves and Bernstein waves into electromagnetic radiation as being respo nsible for intense radio emission from a coronal magnetic loop. Moreov er, 'odd-half harmonic emissions in the solar radio spectrum as well a s the o-mode polarization at the second harmonic of the plasma frequen cy are natural consequence of this proposed model.