Wave-particle interactions with parallel whistler waves: nonlinear and time-dependent effects revealed by Particle-in-Cell simulations

Abstract

We present a self-consistent Particle-in-Cell simulation of the resonant interactions between anisotropic energetic electrons and a population of whistler waves, with parameters relevant to the Earths radiation belt. By tracking PIC particles, and comparing with test-particle simulations we emphasize the importance of including nonlinear effects and time evolution in the modeling of wave-particle interactions, which are excluded in the resonant limit of quasi- linear theory routinely used in radiation belt studies. In particular we show that pitch angle diffusion is enhanced during the linear growth phase, and it rapidly saturates well before a single bounce period. This calls into question the widely used bounce average performed in most radiation belt diffusion calculations. Furthermore we discuss how the saturation is related to the fact that the domain in which the,particles pitch angle diffuse is bounded, and to the well-known problem of $90^{\circ }$ diffusion barrier diffusion barrier.

to appear on Physics of Plasmas 8 pages, 12 figures

References in corpus (3)

• Whistler mode waves and the electron heat flux in the solar wind: Cluster observations
• Observation of relativistic electron microbursts in conjunction with intense radiation belt whistler-mode waves
• The dissipation of solar wind turbulent fluctuations at electron scales

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• Long-term dynamics driven by resonant wave-particle interactions: from Hamiltonian resonance theory to phase space mapping
• Parker Solar Probe evidence for scattering of electrons in the young solar wind by narrowband whistler-mode waves
• ViDA: a Vlasov-DArwin solver for plasma physics at electron scales
• On application of stochastic differential equations for simulation of nonlinear wave-particle resonant interactions