@article{e3097498bc3c445d971624ccf76ab5bd,
title = "High-frequency heating of the solar wind triggered by low-frequency turbulence",
abstract = "The fast solar wind{\textquoteright}s high speeds and non-thermal features require that considerable heating occurs well above the Sun{\textquoteright}s surface. Two leading theories seem incompatible: low-frequency {\textquoteleft}Alfv{\'e}nic{\textquoteright} turbulence, which transports energy outwards and is observed ubiquitously by spacecraft but seems insufficient to explain the observed dominance of ion over electron heating; and high-frequency ion-cyclotron waves, which explain the non-thermal heating of ions but lack an obvious source. Here we argue that the recently proposed {\textquoteleft}helicity barrier{\textquoteright} effect, which limits electron heating by inhibiting the turbulent cascade of energy to the smallest scales, can unify these two paradigms. Our six-dimensional simulations show how the helicity barrier causes the large-scale energy to grow through time, generating small parallel scales and high-frequency ion-cyclotron-wave heating from low-frequency turbulence, while simultaneously explaining various other long-standing observational puzzles. The predicted causal link between plasma expansion and the ion-to-electron heating ratio suggests that the helicity barrier could contribute to key observed differences between fast and slow wind streams.",
author = "Jonathan Squire and Romain Meyrand and Kunz, {Matthew W.} and Lev Arzamasskiy and Schekochihin, {Alexander A.} and Eliot Quataert",
note = "Funding Information: We thank B. Dorland, B. Chandran and A. Mallet for illuminating discussions. J.S. and R.M acknowledge support from the Royal Society Te Apārangi, New Zealand, through Marsden Fund grant number UOO1727 and Rutherford Discovery Fellowship RDF-U001804. M.W.K. and E.Q. were supported by the Department of Energy through the NSF/DOE Partnership in Basic Plasma Science and Engineering, award numbers DE-SC0019046 and DE-SC0019047, with additional support for E.Q. from a Simons Investigator Award from the Simons Foundation. L.A. acknowledges the support of the Institute for Advanced Study, and the work of A.A.S. was supported in part by UK EPSRC grant number EP/R034737/1. This research was part of the Frontera computing project at the Texas Advanced Computing Center, which is made possible by National Science Foundation award number OAC-1818253. Further computational support was provided by the New Zealand eScience Infrastructure (NeSI) high-performance computing facilities, funded jointly by NeSI{\textquoteright}s collaborator institutions and the NZ MBIE, and through the PICSciE-OIT TIGRESS High Performance Computing Center and Visualization Laboratory at Princeton University. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. Publisher Copyright: {\textcopyright} 2022, The Author(s), under exclusive licence to Springer Nature Limited.",
year = "2022",
month = jun,
doi = "10.1038/s41550-022-01624-z",
language = "English (US)",
volume = "6",
pages = "715--723",
journal = "Nature Astronomy",
issn = "2397-3366",
publisher = "Nature Publishing Group",
number = "6",
}