Collisionless energy transfer in kinetic turbulence: field–particle correlations in Fourier space

Abstract

Turbulence is commonly observed in nearly collisionless heliospheric plasmas, including the solar wind and corona and the Earth’s magnetosphere. Understanding the collisionless mechanisms responsible for the energy transfer from the turbulent fluctuations to the particles is a frontier in kinetic turbulence research. Collisionless energy transfer from the turbulence to the particles can take place reversibly, resulting in non-thermal energy in the particle velocity distribution functions (VDFs) before eventual collisional thermalization is realized. Exploiting the information contained in the fluctuations in the VDFs is valuable. Here we apply a recently developed method based on VDFs, the field–particle correlation technique, to a $\unicode[STIX]{x1D6FD}=1$ , solar-wind-like, low-frequency Alfvénic turbulence simulation with well-resolved phase space to identify the field–particle energy transfer in velocity space. The field–particle correlations reveal that the energy transfer, mediated by the parallel electric field, results in significant structuring of the VDF in the direction parallel to the magnetic field. Fourier modes representing the length scales between the ion and electron gyroradii show that energy transfer is resonant in nature, localized in velocity space to the Landau resonances for each Fourier mode. The energy transfer closely follows the Landau resonant velocities with varying perpendicular wavenumber $k_{\bot }$ and plasma $\unicode[STIX]{x1D6FD}$ . This resonant signature, consistent with Landau damping, is observed in all diagnosed Fourier modes that cover the dissipation range of the simulation.

A field–particle correlation analysis of a perpendicular magnetized collisionless shock

“…To ascertain the details of the energy transfer in collisionless shocks, we perform a first-principles, continuum kinetic simulation of a perpendicular collisionless shock and use the field-particle correlation technique (Klein & Howes 2016;Howes, Klein & Li 2017;Klein 2017;Klein, Howes & TenBarge 2017;Howes, McCubbin & Klein 2018;Chen, Klein & Howes 2019;Li et al 2019;Horvath, Howes & McCubbin 2020;Klein et al 2020) to characterize this energy exchange directly in phase space. We consider a reduced dimensionality and simplified geometry to isolate the available energization mechanisms available to the plasma, focusing on the energization mechanisms of shock-drift acceleration for the ions and adiabatic heating for the electrons.…”

Dependence of Solar Wind Proton Temperature on the Polarization Properties of Alfvénic Fluctuations at Ion-kinetic Scales

“…In this study, we refer to KAW-like fluctuations as nonlinear turbulent fluctuations with polarization properties that are consistent with linear KAWs, rather than linear modes. This interpretation does not preclude the possibility of resonant damping (Li et al 2016(Li et al , 2019Klein et al 2017Klein et al , 2020Howes et al 2018; Chen et al 2019) or stochastic heating (e.g., Cerri et al 2021) discussed above; however, additional processes cannot be ruled out. For example, kinetic simulations show perpendicular heating of ions by turbulent processes that may be unrelated to wave damping or stochastic heating, although the exact heating mechanism is still unclear (e.g., Parashar et al 2009;Servidio et al 2012;Vasquez 2015;Yang et al 2017).…”

“…, , other fluctuations may be present that we do not measure. Direct evidence of energy transfer between the fluctuations and protons is needed to confirm this result, for example, using the field-particle correlation method Howes et al 2017;Klein 2017;Klein et al 2017;Chen et al 2019;Li et al 2019). This evidence will require higher-resolution data than provided by Wind.…”

Energy Transfer Between Hot Protons and Electromagnetic Ion Cyclotron Waves in Compressional Pc5 Ultra‐low Frequency Waves

“…Attempts to detect energy transfer between charged particles and various waves or to detect the efficiency of pitch angle scattering of particles by waves have been reported and discussed (C. H. K. Chen et al., 2019; Ergun, Carlson, McFadden, Clemmons, Boehm, 1991; Ergun, Carlson, McFadden, TonThat et al., 1991; Fukuhara et al., 2009; Gershman, F‐Viñas et al., 2017; He et al., 2019; Howes et al., 2017; Katoh et al., 2013, 2018; Kitahara & Katoh, 2016; Kitamura et al., 2018; Klein et al., 2017; Kletzing et al., 2005, 2017; T. C. Li et al., 2019; Shoji et al., 2017). Katoh et al.…”

“…Attempts to detect energy transfer between charged particles and various waves or to detect the efficiency of pitch angle scattering of particles by waves have been reported and discussed (C. H. K. Ergun, Carlson, McFadden, TonThat et al, 1991;Fukuhara et al, 2009;Gershman, F-Viñas et al, 2017;He et al, 2019;Howes et al, 2017;Katoh et al, 2013Katoh et al, , 2018Kitahara & Katoh, 2016;Kitamura et al, 2018;Klein et al, 2017;Kletzing et al, 2005Kletzing et al, , 2017; T. C. Li et al, 2019;Shoji et al, 2017). Katoh et al (2013) focused on the detection of the electron nongyrotropy that is caused by nonlinear wave-particle interactions between whistler mode waves and electrons (e.g., Omura et al, 2008) and tested the feasibility of such analysis in a simulation.…”