Ion-Scale Waves Regulated by Plasma Beta and Cross Helicity: Observational Evidence for the Helicity Barrier in Imbalanced Solar Wind Turbulence
Abstract
Ion-scale waves are believed to play an important role in heating of the solar corona and wind, though their generation mechanism remains unclear. Based on Parker Solar Probe observations, this Letter investigates the occurrence of ion-scale waves in the near-Sun solar wind with heliocentric distances between 0.1 and 0.2 au. Results show that the occurrence rate of left-handed polarized waves significantly depends on the plasma beta (β) and cross helicity (σc). The occurrence rate rapidly increases with decreasing β and increasing σc. Overall, the occurrence rate exceeds 45% when β<0.2 and σc > 0.7 are satisfied. These observations are consistent with the direct predictions of the helicity barrier theory that suggests the generation of ion cyclotron waves via imbalanced magnetized turbulence.
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BibTeX
@misc{zhao2026ionscale,
title = {{Ion-Scale Waves Regulated by Plasma Beta and Cross Helicity: Observational Evidence for the Helicity Barrier in Imbalanced Solar Wind Turbulence}},
author = {G. Q. Zhao and R. Meyrand and H. Q. Feng and H. F. Yang and L. Xiang and Z. Wang},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.29752},
eprint = {2608.29752},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.29752},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Ion-Scale Waves Regulated by Plasma Beta and Cross Helicity: Observational Evidence for the Helicity Barrier in Imbalanced Solar Wind Turbulence
AU - G. Q. Zhao
AU - R. Meyrand
AU - H. Q. Feng
AU - H. F. Yang
AU - L. Xiang
AU - Z. Wang
PY - 2026
DA - 2026/08/30
PB - arXiv
DO - 10.48550/arxiv.2608.29752
UR - https://arxiv.org/abs/2608.29752
AB - Ion-scale waves are believed to play an important role in heating of the solar corona and wind, though their generation mechanism remains unclear. Based on Parker Solar Probe observations, this Letter investigates the occurrence of ion-scale waves in the near-Sun solar wind with heliocentric distances between 0.1 and 0.2 au. Results show that the occurrence rate of left-handed polarized waves significantly depends on the plasma beta (β) and cross helicity (σ_c). The occurrence rate rapidly increases with decreasing β and increasing σ_c. Overall, the occurrence rate exceeds 45% when β<0.2 and σ_c > 0.7 are satisfied. These observations are consistent with the direct predictions of the helicity barrier theory that suggests the generation of ion cyclotron waves via imbalanced magnetized turbulence.
ER -