第九届青年地学论坛

The direct interaction between Mars and solar wind leads to various plasma activities and particle dynamic processes in Martian space. Here we perform a case study: magnetosonic waves and penetrating solar wind H⁺ are observed simultaneously in Martian magnetic pileup region, accompanied by large reflected H⁺ flux. To figure out whether and what role magnetosonic waves play in H⁺ reflection, we use the test particle simulations to quantitively calculate the scattering and diffusion effects of waves on H⁺, as well as the reflection efficiency. The results show that there is a strong Landau resonance for H⁺ at 10–10⁴ eV, with pitch-angle scattering at <(Δα)²> = 10^-2–10^-1 rad² and energy diffusion at <(ΔE_k/E_k0)²> = ~10^-2 on time scale of ~12 s. Surprisingly, the non-resonance effect can also affect the H⁺ with lower energy 1–10 eV. Due to these significant wave-particle interactions, the reflection efficiency of 10³–10⁴ eV H⁺ is 12.30%, which is five times higher than that without magnetosonic waves. Our study suggests that wave-particle interactions can be one of mechanisms for reflecting the penetrating H⁺ to space, modulating the evolution of the Martian plasma and atmospheric environment.

Mars,wave-particle interactions