Eulerian ion energisation in three-dimensional hybrid-Vlasov-Maxwell turbulence
Abstract
In collisionless plasma turbulence, energy is transferred from electromagnetic fluctuations to the particles. However, the relative contributions of different ion energisation mechanisms remain unclear. We investigate ion energisation in three-dimensional hybrid Vlasov--Maxwell simulations of decaying turbulence at βi0=0.25 and βi0=4, where βi0 is the initial ratio of ion thermal to magnetic pressure. Using the exact ion momentum equation, we decompose the ion energisation rate ji·E into the work done on the parallel, diamagnetic, curvature, agyrotropic and polarisation ion currents. This decomposition requires neither gyrotropy nor scale separation and, therefore, remains valid where guiding-centre theory breaks down. We show that the agyrotropic term, which has no guiding-centre counterpart, accounts for 21 % of the energisation at βi0=0.25 and 91 % at βi0=4. We find that the dominant instantaneous energisation term changes with βi0, from the polarisation current at low βi0 to the diamagnetic and agyrotropic currents at high βi0, at all resolved scales. In addition, we show that reversible exchange with the ion bulk flow dominates the instantaneous rate, so the time-integrated energy transfer is larger at βi0=4 even though the instantaneous rate is smaller. Our results provide quantitative evidence that guiding-centre drifts alone cannot describe ion energisation in kinetic-scale turbulence and that the dominant energisation term depends on βi. The results also highlight the key role of non-local thermodynamic-equilibrium effects in energy conversion in collisionless plasma turbulence.
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BibTeX
@misc{richard2026eulerian,
title = {{Eulerian ion energisation in three-dimensional hybrid-Vlasov-Maxwell turbulence}},
author = {L. Richard and S. S. Cerri and O. Pezzi and C. Granier and J. M. TenBarge},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23740},
eprint = {2610.23740},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23740},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Eulerian ion energisation in three-dimensional hybrid-Vlasov-Maxwell turbulence
AU - L. Richard
AU - S. S. Cerri
AU - O. Pezzi
AU - C. Granier
AU - J. M. TenBarge
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23740
UR - https://arxiv.org/abs/2610.23740
AB - In collisionless plasma turbulence, energy is transferred from electromagnetic fluctuations to the particles. However, the relative contributions of different ion energisation mechanisms remain unclear. We investigate ion energisation in three-dimensional hybrid Vlasov--Maxwell simulations of decaying turbulence at β_i0=0.25 and β_i0=4, where β_i0 is the initial ratio of ion thermal to magnetic pressure. Using the exact ion momentum equation, we decompose the ion energisation rate j_i·E into the work done on the parallel, diamagnetic, curvature, agyrotropic and polarisation ion currents. This decomposition requires neither gyrotropy nor scale separation and, therefore, remains valid where guiding-centre theory breaks down. We show that the agyrotropic term, which has no guiding-centre counterpart, accounts for 21 % of the energisation at β_i0=0.25 and 91 % at β_i0=4. We find that the dominant instantaneous energisation term changes with β_i0, from the polarisation current at low β_i0 to the diamagnetic and agyrotropic currents at high β_i0, at all resolved scales. In addition, we show that reversible exchange with the ion bulk flow dominates the instantaneous rate, so the time-integrated energy transfer is larger at β_i0=4 even though the instantaneous rate is smaller. Our results provide quantitative evidence that guiding-centre drifts alone cannot describe ion energisation in kinetic-scale turbulence and that the dominant energisation term depends on β_i. The results also highlight the key role of non-local thermodynamic-equilibrium effects in energy conversion in collisionless plasma turbulence.
ER -