The study of these processes has seen significant progress in recent years thanks to a synergistic approach based on simulations and observations. On the one hand, simulations can deliver output in a temporal and spatial range of scales, going from fluid to electron kinetic. That is partially also due to the advent of GPU facilities that contribute to increasing computational algorithms' power in plasma physics. On the observational side, high cadence measurements of particles and fields and high-resolution 3D measurements of particle distribution functions are currently provided by the missions MMS, Parker Solar Probe, and Solar Orbiter, opening new research scenarios in heliophysics and providing a consistent amount of new data to be analysed. Furthermore, other present and future missions that will give unique plasma measurements around solar system compact objects, such as Bepi Colombo, Juice, Comet Interceptor, and HelioSwarm are demanding the development of new numerical tools for a successful interpretation of the observations.
This session welcomes simulation, observational, and theoretical works relevant to studying the abovementioned processes. We also encourage papers proposing new methods in simulation techniques and data analysis, for example, those rooted in Artificial Intelligence or those based on multi-point satellite observations.
Orals: Tue, 5 May, 16:15–18:00 | Room -2.92
How to cite: Lübke, J., Effenberger, F., Wilbert, M., Fichtner, H., and Grauer, R.: Magnetic mirroring and curvature scattering cause anomalous cosmic-ray transport, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15269, https://doi.org/10.5194/egusphere-egu26-15269, 2026.
The transport of energetic particles is intimately related to the properties of plasma turbulence, a ubiquitous dynamical process that transfers energy across a broad range of spatial and temporal scales. However, the mechanisms governing the interactions between plasma turbulence and energetic particles remain incompletely understood. Here we present comprehensive observations from the upstream region of a quasi-perpendicular interplanetary (IP) shock on 2004 January 22, using data from four Cluster spacecraft to investigate the interplay between turbulence dynamics and energetic particle transport. Our observations reveal a transition in energetic proton fluxes from exponential to power-law decay with increasing distance from the IP shock. This result provides possible observational evidence of a shift in transport behavior from normal diffusion to superdiffusion. This transition correlates with an increase in the time ratio from $\tau_s/\tau_{c}<1$ to $\tau_s/\tau_{c}\gg1$, where $\tau_s$ is the proton isotropization time, and $\tau_{c}$ is the turbulence correlation time. Additionally, the frequency-wavenumber distributions of magnetic energy in the power-law decay zone indicate that energetic particles excite linear Alfvén-like harmonic waves through gyroresonance, thereby modulating the original turbulence structure. These findings provide valuable insights for future studies on the propagation and acceleration of energetic particles in turbulent astrophysical and space plasma systems.
How to cite: Zhao, S., Yan, H., and Liu, T. Z.: Observations of Turbulence and Particle Transport at Interplanetary Shocks: Transition of Transport Regimes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11082, https://doi.org/10.5194/egusphere-egu26-11082, 2026.
Electron-scale instabilities at collisionless shocks are central to plasma dissipation and particle energization, yet their physical origin and nonlinear consequences remain poorly constrained. In this presentation, we investigate the development and impact of electron Kelvin–Helmholtz instability (EKHI) at quasi-perpendicular shocks, which reveals a new pathway for electron acceleration and electron-scale structure formation.
High-resolution particle-in-cell simulations show that intense electron velocity shear naturally forms along the shock surface due to drift motion. When the shear layer thickness approaches electron kinetic scales, it becomes unstable to EKHI. This instability is localized within the shock transition, evolves on electron timescales, and is fundamentally distinct from ion-scale KH modes commonly observed at planetary boundaries.
In the nonlinear stage, the EKHI generates coherent electron vortices embedded within the shock ramp. These vortices are accompanied by strong bipolar parallel electric fields and pronounced charge separation, which effectively generate field-aligned electron beams therein. Interestingly, we further demonstrate that EKHI between the reforming shock fronts can produce electron vortex magnetic holes, which are electron-scale coherent structures frequently observed in turbulent plasma. This indicates a possible generation mechanism for electron-scale magnetic holes in Earth's magnetosheath.
These results identify EKHI as a key mechanism linking shock-surface shear flows, electron vortices, magnetic holes, and electron energization at quasi-perpendicular shocks. This process provides a viable pre-acceleration channel for electrons and has broad implications for kinetic-scale energy conversion at collisionless shocks.
How to cite: Guo, A., Lu, Q., Lu, S., Yao, S., Yang, Z., and Gao, X.: Electron Kelvin-Helmholtz Instability at Quasi-perpendicular Shocks, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8006, https://doi.org/10.5194/egusphere-egu26-8006, 2026.
Collisionless shock waves and plasma turbulence play fundamental roles in particle acceleration and energy dissipation in space plasmas. In the heliosphere, the inherently turbulent solar wind continuously interacts with planetary bow shocks and interplanetary shocks. Such pre-existing turbulence can modulate the shock front, influence particle acceleration and transport, and modify the plasma conditions and plasma stability in the vicinity of the shock. We present a novel modelling setup in which we use MHD simulations to generate turbulent fields that are dynamically input to our hybrid shock simulations. This allows us to study the interaction between realistic plasma turbulence and a shock wave. Here we report results on the influence of upstream turbulence on plasma stability against ion kinetic instabilities downstream of a perpendicular shock. We find that while turbulence can locally drive plasma towards an unstable configuration, it generally makes the downstream plasma more stable against proton cyclotron and mirror mode instabilities. We also find that a sharp low limit in βparallel–Tperp/Tparallel “Brazil plots”, sometimes also seen in observations, can be caused by tracks representing adiabatic evolution of plasma in magnetic islands.
How to cite: Vuorinen, L., Burgess, D., Trotta, D., and Koller, F.: Influence of upstream turbulence on plasma stability at a perpendicular shock: hybrid simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7356, https://doi.org/10.5194/egusphere-egu26-7356, 2026.
In solar wind turbulence, the energy transfer/dissipation rate is typically estimated using MHD third-order structure functions calculated using spacecraft observations. However, the inherent anisotropy of solar wind turbulence leads to significant variations in structure functions along different observational directions, thereby affecting the accuracy of energy-dissipation rate estimation. An unresolved issue is how to optimise the selection of observation angles under limited directional sampling to improve estimation precision. We conduct a series of MHD turbulence simulations with different mean magnetic field strengths, B0. Our analysis of the third-order structure functions reveals that the global energy dissipation rate estimated around a polar angle of θ = 60◦ agrees reasonably with the exact one. The speciality of 60◦ polar angle can be understood by the Mean Value Theorem of Integrals, since the spherical integral of the polar-angle component of the divergence of Yaglom flux is zero, and this polar-angle component changes sign around 60◦. Existing theory on the energy flux vector as a function of the polar angle is assessed, and supports the speciality of 60◦ polar angle. The angular dependence of the third-order structure functions is further assessed with virtual spacecraft data analysis. The present results can be applied to measure the turbulent dissipation rates of energy in the solar wind, which are of potential importance to other areas in which turbulence takes place, such as laboratory plasmas and astrophysics.
How to cite: Yang, Y., Jiang, B., Gao, Z., Pecora, F., Gao, K., Li, C., Oughton, S., Matthaeus, W., and Wan, M.: Angular dependence of third-order law in anisotropic MHD , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7873, https://doi.org/10.5194/egusphere-egu26-7873, 2026.
Modelling turbulence kinetically in space remains challenging due to the multiscale nature of plasma. An alternative approach is to adopt a fluid model hierarchy and close it using a phenomenological expression or law derived from local kinetic simulations. We address this challenge by examining decaying turbulence in the near-Earth magnetosheath using fully kinetic particle-in-cell (PIC) simulations [1]. We apply machine learning techniques to extract a non-local five-moment electron-pressure-tensor closure trained on these simulations. The data are carefully split across simulations initialized with different initial conditions, while maintaining the same turbulence and temperature levels. We evaluate the learned “equation of state” using energy-channel diagnostics, with emphasis on the pressure–strain interaction (a key mediator of turbulence heating). The new global closure outperforms common local approaches (e.g., double-adiabatic [2] and MLP-type closures [3]) in reconstructing key statistics. An equation of state trained on simulations with fewer particles per cell generalises to more accurate simulations with a higher number of particles per cell and different turbulent initialisations, while using the same physical parameters. Off-diagonal terms are more challenging to predict, but performance improves with the quantity of training data.
Finally, we couple this data-driven electron closure with kinetic ion dynamics, advancing toward hybrid kinetic simulations in which electrons are represented by a neural network-based equation of state. This hybrid physics-informed machine learning framework offers a pathway to computationally efficient models with improved physical realism, potentially enabling both predictive simulations and parameter inference in heliospheric and magnetospheric applications.
How to cite: Miloshevich, G., Vranckx, L., de Oliveira Lopes, F. N., Dazzi, P., Arrò, G., and Henri, P.: Electron Neural Closure for Turbulent Magnetosheath Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12428, https://doi.org/10.5194/egusphere-egu26-12428, 2026.
In collisionless plasmas, turbulence generates intermittent small-scale structures such as intense, thin current sheets, within which magnetic reconnection can occur. These structures, and reconnection in particular, are thought to play a key role in turbulence dynamics, energy dissipation, and particle energisation. The Earth’s magnetosheath, a highly turbulent region downstream of the bow shock, provides a natural laboratory for studying these nonlinear plasma processes. The Magnetospheric MultiScale (MMS) mission offers high-resolution, multi-point observations that are ideally suited to resolving small-scale structures in this environment. However, identifying and characterising such structures in spacecraft observations remains challenging due to their localised nature, complex magnetic topology, and the wide range scales involved.
We propose an unsupervised machine learning approach to systematically identify and characterise these structures, with specific emphasis on magnetic reconnection sites within turbulent plasma observations. Our method uses the Toeplitz Inverse-Covariance Clustering (TICC) algorithm, which models each cluster as a time-invariant correlation network, enabling the detection of complex patterns in turbulence. We evaluate TICC’s ability to identify reconnection events against existing datasets and interpret its clusters using the network-based feature scores. Finally, we assess the turbulence properties associated with the identified structures and the prevalence of magnetic reconnection across multiple intervals. This study aims to provide key insight into how the role of turbulent plasmas may vary across different turbulent environments.
How to cite: Quijia Pilapaña, P., Stawarz, J., and Smith, A.: Characterising Small-Scale Structures in the Turbulent Magnetosheath Using Unsupervised Machine Learning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11844, https://doi.org/10.5194/egusphere-egu26-11844, 2026.
Magnetic reconnection plays an important role in the turbulent relaxation of space and astrophysical plasmas, such as the solar corona, solar wind, and Earth’s magnetosheath. Recent studies have shed light on the role of magnetic reconnection as an efficient energy dissipation mechanism in these large-scale turbulent systems. However, the relative role of magnetic reconnection in dissipating turbulent energy in these macroscopic systems is still not fully understood. To investigate these issues, we simulate a turbulent plasma system using magnetohydrodynamic (MHD) simulations. A large number of reconnection sites are found, and their statistical properties are quantified. The study reveals, for the first time, that the distribution of upstream reconnecting fields is strongly correlated with the distribution of global fields at the energy-containing scales. To further explore these relations in weakly collisional systems, we perform a similar analysis on kinetic Particle-in-Cell (PIC) simulations of plasma turbulence and on in situ observations of the terrestrial magnetosheath using the Magnetospheric Multiscale Mission (MMS). Notably, the key conclusions drawn from MHD simulations remain valid in both the kinetic simulations and MMS observations. These findings are expected to significantly refine theoretical estimates of reconnection rates and heating rates resulting from magnetic reconnection.
How to cite: Khan, M. B., Shay, M. A., Oughton, S., Matthaeus, W. H., Haggerty, C., Adhikari, S., Cassak, P. A., Yang, Y., Bandyopadhyay, R., Roy, S., O’Donnell, D., and Fordin, S.: Turbulent fluctuations at the Correlation Scale as the Driver of Magnetic Reconnection, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22923, https://doi.org/10.5194/egusphere-egu26-22923, 2026.
As the solar wind propagates through interplanetary space, adiabatic expansion preferentially cools the plasma in the direction perpendicular to the mean magnetic field, while leaving the temperature parallel to the field largely unaffected. The combined effect of the growing temperature anisotropy and the more rapid decrease of magnetic energy relative to the parallel pressure naturally drives the plasma toward the firehose instability threshold. Concurrently, the turbulent cascade from large to small scales leads to kinetic-scale dissipation, resulting in plasma heating and the potential development of suprathermal tails in velocity distribution functions. A central open question is how turbulence-driven heating competes with expansion-induced temperature anisotropies to regulate the onset and nonlinear evolution of kinetic instabilities. In this work, we present the first fully kinetic three-dimensional particle-in-cell (PIC) simulations of an expanding-box system that includes large-scale turbulent forcing, mimicking Alfvénic fluctuations. Our simulations reveal the emergence of suprathermal tails in the electron velocity distribution functions driven by expansion, suggesting an origin in the interplay between turbulence and the firehose instability. This work aims to bridge solar wind observations and theoretical models by providing a unified, fully kinetic framework that captures the coupled effects of expansion, turbulence-driven heating, and kinetic instabilities at electron scales.
How to cite: Péters de Bonhome, M., Bacchini, F., and Pierrard, V.: Formation of Suprathermal Electron Tails in an Expanding, Turbulent Solar Wind: Insights from Fully Kinetic Particle-in-Cell Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11350, https://doi.org/10.5194/egusphere-egu26-11350, 2026.
We present a model of the heliospheric magnetic field that combines a large-scale Parker Spiral component with a small-scale turbulent contribution generated using a wavelet-based approach. The turbulent fluctuations are constructed to reproduce key properties of magnetic turbulence observed in the expanding solar wind, including a radially decreasing amplitude and a spatially varying correlation length. The wavelet-based method is adapted from a previously developed Cartesian model through the introduction of a new coordinate system, which ensures the correct radial scaling of the turbulence correlation length. This approach allows us to model a wider spectral range of fluctuations than is typically achievable with magnetohydrodynamic simulations, a crucial requirement for accurately describing gyroresonant scattering of energetic particles. The model is designed for future applications in studies of energetic particle transport in the heliosphere.
How to cite: Malara, F., Larosa, A., Pucci, F., Pezzi, O., Sorriso-Valvo, L., Chiappetta, F., Chimenti, M., Nisticò, G., Perri, S., and Zimbardo, G.: Modelling the heliospheric magnetic field through wavelet-based synthetic turbulence, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20991, https://doi.org/10.5194/egusphere-egu26-20991, 2026.
As a universal nonlinear structure in space plasma, electron phase space holes, also named as electrostatic solitary waves (ESWs), have a 60-year research history. An important challenge has been to reveal the microscopic evolutionary process of ESWs. Previous simulations have shown that collision coalescences determine whether several weak ESWs can evolve into a strong one. However, the simulated collision coalescence has not yet been demonstrated in observations. Here, we employ coordinated observations from the MMS multi-satellite mission to unveil two distinct evolutionary processes: collision coalescence and mutual penetration of ESWs in space plasmas. Subsequently, collision simulations reveal that the conditions for coalescence are closely linked to the ratio of the maximum capture velocity of the trapped electrons to the hole velocity, consistent with the findings of energy balance analysis based on the virial theorem and successfully explaining the observed collision coalescence and mutual penetration of ESWs. Therefore, we provide a direct observational evidence to collision coalescence and mutual penetration of ESWs for the first time.
How to cite: Dong, Y. and Yuan, Z.: Collision coalescence and mutual penetration of electron phase space holes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2476, https://doi.org/10.5194/egusphere-egu26-2476, 2026.
Alpha particles constitute the most energetic ion population in the solar wind and play an important role in turbulent energy conversion and ion-scale heating. Yet, the physical processes governing their temperature evolution, anisotropy development, and differential streaming remain incompletely understood. Using Parker Solar Probe observations and 2.5D particle-in-cell simulations, we investigate how the alpha–proton temperature ratio regulates the subsequent alpha heating efficiency and associated kinetic signatures. The observations reveal that alpha heating and anisotropy are strongly modulated by the local value of temperature ratio. The simulations reproduce these trends, showing that increasing temperature ratio lowers the growth of alpha thermal energy, anisotropy, and differential drift. These results demonstrate that the alpha heating pathway could be self-regulated by its initial thermodynamic state, with hotter alphas remaining farther from the instability threshold and experiencing less resonant energization. Our findings provide new constraints on ion-scale dissipation in the near-Sun solar wind and offer a unified interpretation of alpha-proton heating.
How to cite: Xiong, Q. and Huang, S.: Alpha Particle Heating and Anisotropy in the Solar Wind Turbulence: Insights from PSP Observations and PIC Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4789, https://doi.org/10.5194/egusphere-egu26-4789, 2026.
One of the key questions about magnetic reconnection is to understand how energy is partitioned between ions and electrons, especially inside the EDR and in the outflow regions. This requires studying the energy transport terms corresponding to kinetic, thermal and electromagnetic energies respectively, along with the energy conversion terms. Previous studies have shown that ion energy flux dominates close to the EDR in magnetopause reconnection, while the electron energy flux is dominant inside it. However, one must be careful while computing the energy transport terms using MMS data, since the results can be dominated by uncertainty. This is particularly true for magnetotail reconnection, where the plasma is tenuous. Here, we present a detailed analysis of the errors in these energy transport terms, and perform a comparative study between reconnection events observed in the magnetopause, magnetosheath and magnetotail regions.
How to cite: Roy, S., Vörös, Z., Settino, A., Nakamura, R., Roberts, O., Yang, Y., Bandyopadhyay, R., and Matthaeus, W. H.: Estimating errors in energy transport terms during magnetic reconnection, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14700, https://doi.org/10.5194/egusphere-egu26-14700, 2026.
We present a particle-in-cell (PIC) simulation of decaying turbulence with initial conditions representative of the solar wind, in which magnetic depressions form during the nonlinear phase. We analyse the statistical properties of these structures, including size and intensity. We analyse a few of them in detail, looking at the properties of ions and electrons inside and outside them. Using virtual spacecraft, we simulate how these structures would be observed in situ by real spacecraft. We also analyse the trajectories of a few macroparticles entering these structures and undergoing trapping. We compare our simulation results with recent Solar Orbiter observations in the solar wind.
How to cite: Pucci, F., Karlsson, T., Arrò, G., Simon-Wedlund, C., Preisser, L., Ballerini, G., Henri, P., Califano, F., and Volwerk, M.: Magnetic depressions in a kinetic turbulence simulation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12574, https://doi.org/10.5194/egusphere-egu26-12574, 2026.
Understanding and modelling turbulence in space plasmas requires capturing kinetic effects that go beyond standard fluid closures. In the present work, we present a data-driven framework that combines unsupervised clustering and sparse equation discovery to identify effective closures in turbulent plasmas. Our primary focus is on solar-wind observations, but with possible applications to magnetospheric environments.
We use unsupervised clustering methods, more specifically k-means, to identify dynamically similar regions in both in situ spacecraft data and numerical simulations. The first part of the project is focused on numerical simulations. Clustering is performed on multidimensional feature spaces constructed from plasma moments, fields, and other pressure-tensor-related quantities, applied to either 3D or 2D simulations. The resulting clusters define coherent regions characterized by comparable kinetic activity, anisotropy, and turbulence properties.
These clustered regions serve as domains for sparse identification of nonlinear dynamics (SINDy). Particular emphasis is placed on exploring data-driven closures involving the pressure tensor, including anisotropic and nongyrotropic contributions, and understanding their role in momentum and other dynamical equations.
The framework is designed to function consistently across both in situ measurements, such as Magnetospheric Multiscale (MMS) observations, and PIC simulations, enabling direct validation and comparison. This combined approach provides a structured method for discovering interpretable, region-specific closures in turbulent space plasmas and supports the development of reduced models directly informed by observations.
How to cite: de Oliveira Lopes, F. N., Dazzi, P., Miloshevich, G., and Keppens, R.: Data-Driven Identification of Region-Dependent Pressure Tensor Closures in Turbulent Space Plasmas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21072, https://doi.org/10.5194/egusphere-egu26-21072, 2026.
Jupiter has the most powerful aurora in the solar system, which is currently studied by NASA's Juno spacecraft. Observations above Jupiter's poles have shown that electrons accelerated toward Jupiter, which contribute to auroral emissions, are frequently accompanied by electrons accelerated in the opposite direction, deep into Jupiter's large magnetosphere. These energetic, bidirectional electrons often exhibit broadband energy distributions consistent with a stochastic particle acceleration mechanism. Alfvén waves, which are observed as magnetic field fluctuations, are being discussed to play an important role in the acceleration process. These waves are belived to be generated by the discontinuous radial plasma transport from Jupiter's plasma source Io to the outer magnetosphere. We investigate magnetic field and plasma measurements in Jupiter's middle magnetosphere, where Alfvénic fluctuations have been observed, to analyze if a correlation between magnetic field fluctuations and plasma velocity fluctuations can be observed.
How to cite: Piasecki, J., Saur, J., Szalay, J., and Clark, G.: Magnetic field fluctuations in Jupiter's middle magnetosphere on auroral field lines, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21383, https://doi.org/10.5194/egusphere-egu26-21383, 2026.
The current sheet stress balance conditions describe the equilibrium between magnetic stresses and plasma pressure across a thin current sheet. We build upon existing work developed in the context of magnetotail reconnection to derive a set of stress balance conditions for reconnection outflows in the solar wind, which are typically characterised by a bifurcated reconnection current sheet (RCS). Applying our framework to a symmetric bifurcated RCS model, we determine the outflow region opening angle and beam population properties, obtaining values consistent with observations of reconnection in the solar wind. We then validate our framework against observations of solar wind reconnection outflows from Solar Orbiter, highlighting one event with properties compatible with our simple symmetric model. For this event, we estimate an outflow region opening angle ranging from 3.4°-8.2°, in line with values reported in previous studies. We also reconstruct the outflow beam distribution functions and find that the predicted beam velocities and temperatures match observations well, although the densities are underestimated. Overall, our stress balance framework captures some of the key features of solar wind reconnection outflow, including current sheet bifurcation and counter-streaming beams. Future work will extend the framework to asymmetric reconnection geometries.
How to cite: Suen, G. H. H., Owen, C., and Verscharen, D.: Current sheet stress balance models of bifurcated current sheet reconnection in the solar wind, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7974, https://doi.org/10.5194/egusphere-egu26-7974, 2026.
In recent years, significant progress has been made in the velocity-moment-based quasilinear (QL) theory of waves and instabilities in plasmas with non-equilibrium velocity distributions (VDs) of the Kappa (or κ-) type. However, the temporal variation of the parameter κ, which quantifies the presence of suprathermal particles, is not fully captured by such a QL analysis, and typically κ remains constant during plasma dynamics. We propose a new QL modeling that goes beyond the limits of a previous approach (Moya et al. 2021), realistically assuming that the quasithermal core cannot evolve independently of energetic suprathermals. The case study is done on the electron-cyclotron (EMEC) instability generated by anisotropic bi-Kappa electrons with A = T⊥/T∥ > 1 (∥, ⊥ denoting directions with respect to the background magnetic field). The parameter κ self-consistently varies through the QL equation of kurtosis (fourth-order moment) coupled with temporal variations of the temperature components, relaxing the constraint on the independence of the low-energy (core) electrons and suprathermal high-energy tails of VDs. The results refine and extend previous approaches. A clear distinction is made between regimes that lead to a decrease or an increase in the κ parameter with saturation of the instability. What predominates is a decrease in κ, i.e., an excess of suprathermalization, which energizes suprathermal electrons due to self-generated wave fluctuations. Additionally, we found that VDs can evolve towards a quasi-Maxwellian shape (as κ increases) primarily in regimes with low beta and initial kappa values ≳ 5. The relaxation of bi-Kappa electron VDs under the action of instability is only partial by reducing the temperature anisotropy, whereas the contribution of wave fluctuations generally enhances suprathermal electrons. The present results show preliminary agreement with in-situ observations in the solar wind, suggesting that the new QL model could provide a sufficiently explanatory theoretical basis for the kinetic instabilities in natural plasmas with Kappa-like distributions.
How to cite: Moya, P. S., Navarro, R., Lazar, M., Yoon, P., López, R., and Poedts, S.: Quasilinear approach of bi-Kappa distributed electrons with dynamic κ parameter. EMEC instability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11406, https://doi.org/10.5194/egusphere-egu26-11406, 2026.
In plasma physics, one of the main obstacles to unravelling the mechanisms responsible for energy transfer between electromagnetic fields and plasma particles is the multiscale nature of plasma phenomena. In this context, plasma turbulence plays a fundamental role because it transports energy across spatial scales from the energy injection scales (large-scales) down to small-scales at which energy is dissipated. One of the key open challenges in plasma turbulence research is understanding how the small-scale turbulent dynamics couple into and influences the large-scale behaviour of the system and how that influences the energy budget and energy transport at system scales. One approach to address this challenge is to employ so-called Large Eddy Simulations, where the large scales of the system are directly simulated, and the small-scale anomalous dynamics are parameterized using Sub-Grid-Scale (SGS) models for the anomalous contributions. However, the appropriate SGS models for describing collisionless plasma systems with large scale separations remain poorly constrained.
In this work, we employ a series of Vlasov-Hybrid simulations modelling conditions similar to turbulence in Earth’s magnetosheath to characterize the anomalous contributions to the total electric field from each term in the generalized Ohm’s law for different plasma conditions. We discuss the role of anomalous (turbulent) resistivity and anomalous viscosity on the total electric field, and we show that the most relevant anomalous contribution comes from the Hall term for plasmas with low plasma beta. We provide insight on how to model SGS terms in collisionless plasmas at scales within the kinetic range where terms associated with sub-ion physics are not necessarily negligible. To do this we establish the dependence of the anomalous terms on resolved quantities such as the magnetic field, electric current density and plasma vorticity and we evaluate their contribution to the magnetic field generation. Since electric fields strongly contribute to plasma particle energization, our results are relevant for better understanding the cross-scale energy transfer and the anomalous contribution to the energy budget.
How to cite: Agudelo Rueda, J. A., Stawarz, J. E., Franci, L., Granier, C., and Yokoi, N.: On the Anomalous Contribution to the Electric Field in Turbulent Collisionless Plasmas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19281, https://doi.org/10.5194/egusphere-egu26-19281, 2026.
Posters virtual: Thu, 7 May, 14:00–18:00 | vPoster spot 1b
EGU26-15102 | Posters virtual | VPS23
Anisotropic energy transfer rate quantified by LPDE and directional averaging methods in MHD turbulenceThu, 07 May, 14:15–14:18 (CEST) vPoster spot 1b
The energy cascade rate (ε) depicts the energy transfer in a turbulent system. In incompressible magneto-hydrodynamic (MHD) turbulence, ε is linked to the third-order structure function (Yaglom vector) via the Yaglom/Politano–Pouquet law in the inertial range. In this study, we compare three estimators of ε in anisotropic MHD turbulence: (1) the lag polyhedral derivative ensemble (LPDE) technique that reconstructs the divergence of the Yaglom vector via tetrahedral linear gradients; (2) a directional-averaged third-order estimator that evaluates the Yaglom vector along a finite number of lag directions and averages over solid angle; and (3) the Yaglom vector on 60 degree with respect to the mean magnetic field direction. To ensure a fair comparison in more realistic MHD turbulence, we emulate a multipoint virtual mission within anisotropic three-dimensional MHD simulations with a guide field B₀ along the z-axis. This work illuminates the reliable regime for LPDE and directional-averaging methods, and also tests whether 60 degree Yaglom vector is an accurate estimate of ε, providing practical guidance in both simulation and observational turbulence analysis.
How to cite: Gao, Z., Yang, Y., Jiang, B., and Pecora, F.: Anisotropic energy transfer rate quantified by LPDE and directional averaging methods in MHD turbulence, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15102, https://doi.org/10.5194/egusphere-egu26-15102, 2026.
