MHD versus kinetic effects in the solar coronal heating: a two stage mechanism
Abstract
Description
Using Particle-In-Cell simulations i.e. in the kinetic plasma description the discovery of a new mechanism of parallel electric field generation was recently reported. Here we show that the electric field generation parallel to the uniform unperturbed magnetic field can be obtained in a much simpler framework using the ideal magnetohydrodynamics (MHD) description. In ideal MHD the electric field parallel to the uniform unperturbed magnetic field appears due to fast magnetosonic waves which are generated by the interaction of weakly non-linear Alfvén waves with the transverse density inhomogeneity. In the context of the coronal heating problem a new {\it two stage mechanism} of plasma heating is presented by putting emphasis, first, on the generation of parallel electric fields within an {\it ideal MHD} description directly, rather than focusing on the enhanced dissipation mechanisms of the Alfvén waves and, second, dissipation of these parallel electric fields via {\it kinetic} effects. It is shown that for a single Alfvén wave harmonic with frequency $ν= 7$ Hz, and longitudinal wavelength $λ_A = 0.63$ Mm for a putative Alfvén speed of 4328 km s$^{-1}$, the generated parallel electric field could account for 10% of the necessary coronal heating requirement. We conjecture that wide spectrum (10$^{-4}-10^3$ Hz) Alfvén waves, based on the observationally constrained spectrum, could provide the necessary coronal heating requirement. By comparing MHD versus kinetic results we also show that there is a clear indication of the {\it anomalous resistivity} which is 100s of times greater than the classical Braginskii value.
presentation at SOHO17, Giardini Naxos, Sicily, 7-12 May, 2006, to appear in SOHO17 proceedings
presentation at SOHO17, Giardini Naxos, Sicily, 7-12 May, 2006, to appear in SOHO17 proceedings
Keywords
Citation
Consulte el texto completo en el siguiente enlace:
https://arxiv.org/abs/astro-ph/0606658
http://arxiv.org/abs/astro-ph/0606658
SOHO-17. 10 Years of SOHO and Beyond, Proceedings of the conference held 7-12 May, 2006 at Giardini Naxos, Sicily, Italy. Edited by H. Lacoste and L. Ouwehand. ESA SP-617. European Space Agency, 2006. Published on CDROM, p.111.1
http://arxiv.org/abs/astro-ph/0606658
SOHO-17. 10 Years of SOHO and Beyond, Proceedings of the conference held 7-12 May, 2006 at Giardini Naxos, Sicily, Italy. Edited by H. Lacoste and L. Ouwehand. ESA SP-617. European Space Agency, 2006. Published on CDROM, p.111.1