A study of mode conversion in an oxygen–hydrogen plasma

Abstract

Linear mode conversion is considered between the ion-cyclotron and magnetosonic branches in a multispecies plasma with parallel magnetic field gradients. The results are interpreted in terms of ion conic heating. The mode-conversion coefficients are solved using perturbation theory, a phase integral approach, and saddle-point theory. These results are compared with numerical calculations. The coefficients thus obtained demonstrate that substantial coupling occurs between the four propagating modes, and a definite absorption occurs. Such absorption corresponds to ion heating and is, under realistic circumstances, sufficient to explain the outflow and heating of ionospheric oxygen.

2D full-wave simulation of waves in space and tokamak plasmas

“…Ref. [12] suggested that polarization reversal and mode conversion occurs at the crossover frequency, where the left-hand (LHP) and right-hand (RHP) polarization modes cross each other in the dispersion relation, from LHP to RHP polarization and such RHP EMIC waves can propagate to the inner magnetosphere, which is consistent with 1D full-wave calculations [13,14].…”

Full‐wave modeling of EMIC waves near the He+ gyrofrequency

“…Polarization reversal occurs where ω = ω cr , such that waves with ω > ω cr are RHP, while they are LHP for ω Lcut < ω < ω cr . At the crossover location, mode conversion between Classes I and II can also occur [e.g., Smith and Brice, 1964;Johnson et al, 1995]. At the point where ω = ω cr , these waves should reverse polarization from LHP to RHP.…”

“…Class II is the H + cyclotron branch, which can be excited near the magnetic equator and propagate along the magnetic field toward higher latitude and increasing magnetic field strength. Johnson et al [1995] demonstrated that there is mode conversion θ k window where the modes can be coupled. Once the waves become RHP, they continue to be guided to the location where ω = ω bb and the waves become unguided for ω < ω bb [Rauch and Roux, 1982].…”

Localization of Ultra-Low Frequency Waves in Multi-Ion Plasmas of the Planetary Magnetosphere

“…Interestingly, the Buchsbaum resonance is also a cutoff condition of the Left-Hand Polarization (LHP) EMIC waves (Johnson et al 1995). In Earth's magnetosphere, as these waves propagate along B 0 , the wave normal angle increases and becomes nearly 90° when waves reach the Buchsbaum resonance.…”