Beam-driven ECH waves: A parametric study

Electron cyclotron harmonic (ECH) waves play a significant role in driving the diffuse aurora, which constitutes more than 75% of particle energy input into ionosphere. ECH magnetospheric plasmas have long been thought to be excited predominantly by loss cone anisotropy (velocity–space gradients) that arises naturally planetary dipole field. Recent THEMIS observations, however, indicate an electron beam can also excite such Earth's magnetotail. The ambient and plasma conditions under excitation take place are unknown. Knowledge would allow us further explore relative contribution this mechanism wave scattering electrons at Earth outer planets. Using hot dispersion relation, we address nature beam-driven conduct comprehensive parametric survey instability. We find growth is provided resonances both first higher orders. these unstable wide range conditions. rate increases with density, velocity, temperature; it decreases increasing temperature ( T ? / ?), cold density temperature. Such abound magnetotail, where heated earthward convection magnetic reconnection coexist colder ionospheric electrons.