Three-dimensional simulations of firehose instability: fluctuating fields and particle acceleration

Abstract:

Observations of waves in plasmas with anisotropic pressure close to firehose marginal stability level are often associated with the presence of energetic ion populations. Possible role of electric field fluctuations produced by firehose instability in particle acceleration is not well understood [1]. We investigate properties of structures produced by the firehose instability and its role in particle heating. Results of three-dimensional numerical simulations in Hall-MHD approximation are compared with properties of one-dimensional analytical solutions and results of two-dimensional simulations. Processes of particle scattering and acceleration in the generated structures are studied in detail by using test particle method.

[1] Stasiewicz K. et al., Acceleration of solar wind ions to 1 MeV by electromagnetic structures upstream of the Earth's bow shock, Europhysics Letters, Vol. 102, 49001, 2013.