ELECTRON MODULATION AND ION-CYCLOTRON WAVES OBSERVED BY FAST

New observations from the FAST satellite demonstrate strong wave-parti cle interactions between energetic electrons and H+ EMIC waves in inve rted-V arcs. The intense waves are shown to occur in strong upward cur rent regions which contain intense downgoing field-aligned electron fl uxes. Electrons near the inverted-V spectral peak have large, factor o f 2 to 10, coherent flux modulations at or near the wave frequency. Th e electron modulations are typically centered at about f(CH+)/2, where f(CH+) is the local H+ cyclotron frequency. The EMIC waves are broadb anded, extending from about 0.3f(CH+) to 0.7f(CH+). These waves also a ccelerate cold secondary electrons, forming counterstreaming field-ali gned electrons at energies up to about 300 eV.In addition, electron mo dulations at f(CH+) are observed in the density cavities associated wi th upgoing ion beams. Intense waves at f(CH+) are simultaneously detec ted and shown to have a magnetic component similar to the EMIC waves.