Publication Date:
2014-03-13
Description:
A three-dimensional (3D) particle-in-cell (PIC) simulation of the whistler anisotropy instability is carried out for a collisionless, homogeneous, magnetized plasma with β e = 0.10. This is the first 3D PIC simulation of the evolution of enchanced fluctuations from this growing mode driven by an anisotropic electron velocity distribution with T ⊥ e / T ‖ e 〉 1 where ⊥ and ∥ represent directions perpendicular and parallel to the background magnetic field B o , respectively. The early-time magnetic fluctuation spectrum grows with properties reflecting the predictions of linear theory with narrowband maxima at kc / ω e ≃ 1 and k × B o = 0, and a wavevector anisotropy in the sense of k ⊥ 〈 〈 k ∥ . Here ω e represents the electron plasma frequency. At later times the fluctuations undergo both a forward transfer to shorter wavelengths, also with k ⊥ 〈 〈 k ∥ , and an inverse transfer to longer wavelengths with wavevector anisotropy k ⊥ 〉 〉 k ∥ . The inverse transfer is consistent with a prediction of nonlinear three-wave coupling theory.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
