Two-Fluid Description of Collisionless Perpendicular Shocks

GOMEZ, D. O.; MORALES, L. F.; DMITRUK, P.; BERTUCCI, C.

New Orleans

Congreso; American Geophysical Union Fall Meeting 2017; 2017

AGU

Collisionless shocks are ubiquitous in space physics and astrophysics,such as the bow shocks formed by the solar wind in front of planets, thetermination shock at the heliospheric boundary or the supernova shockfronts expanding in the interstellar plasma. Although the one-fluidmagnetohydrodynamic framework provides a reasonable description of thelarge scale structures of the upstream and downstream plasmas, it fallsshort of providing an adequate description of the internal structure ofthe shock. A more comprehensive description of the inner and outerfeatures of collisionless shocks would require the use of kinetictheory. Nonetheless, in the present work we show that a completetwo-fluid framework (considering the role of both ions and electrons inthe dynamics) can properly capture some of the features observed in realshocks. For the specific case of perpendicular shocks, i.e. cases inwhich the magnetic field is perpendicular to the shock normal, weintegrate the one-dimensional two-fluid MHD equations numerically, todescribe the generation of shocks and their spatial structure along theshock normal. Starting from finite amplitude fast-magnetosonic waves,our simulations show the generation of a stationary fast-magnetosonicshock. More importantly, we show that the ramp thickness is of the orderof a few electron inertial lengths. The parallel and perpendicularcomponents of the self-consistent electric field are derived, and theirrole in accelerating particles is discussed.