How Alfvén waves energize the solar wind: Heat versus work

Jean C. Perez, Benjamin D.G. Chandran, Kristopher G. Klein, Mihailo M. Martinović

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

A growing body of evidence suggests that the solar wind is powered to a large extent by an Alfvén-wave (AW) energy flux. AWs energize the solar wind via two mechanisms: heating and work. We use high-resolution direct numerical simulations of reflection-driven AW turbulence (RDAWT) in a fast-solar-wind stream emanating from a coronal hole to investigate both mechanisms. In particular, we compute the fraction of the AW power at the coronal base () that is transferred to solar-wind particles via heating between the coronal base and heliocentric distance, which we denote by, and the fraction that is transferred via work, which we denote by. We find that ranges from 0.15 to 0.3, where is the Alfvén critical point. This value is small compared with one because the Alfvén speed exceeds the outflow velocity at, where, so the AWs race through the plasma without doing much work. At is a modest fraction of. We find that heating is more effective than work at, the AWs are in an approximate sense 'stuck to the plasma', which helps them do pressure work as the plasma expands. However, much of the AW power has dissipated by the time the AWs reach, so the total rate at which AWs do work on the plasma at A, even though the total rate at which AW energy is transferred to particles at r_{A}$]]> is a small fraction of.

Original languageEnglish (US)
Article number905870218
JournalJournal of Plasma Physics
DOIs
StateAccepted/In press - 2021

Keywords

  • astrophysical plasmas
  • plasma nonlinear phenomena
  • space plasma physics

ASJC Scopus subject areas

  • Condensed Matter Physics

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