Electron and Ion Heating During Magnetic Reconnection in Weakly Collisional Plasmas

Numata, Ryusuke; Loureiro, Nuno F.

doi:10.7566/jpscp.1.015044

Cited by 11 publications

(15 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is important to point out that the restriction to low β e limits the applicability of our conclusions in the solar wind, where, more often than not, β e ∼ 1, but our results will be more relevant to the turbulence closer to the Sun and in the corona: indeed, at the perihelion (approximately 10 solar radii) of the upcoming Parker Solar Probe mission, β e ≈ 0.01, at least in fast-solar-wind streams (Chandran et al 2011). Moreover, the growth-rate scaling (3.2) appears to be quite robust even at moderately large β e : Numata & Loureiro (2015) showed that, keeping all other parameters fixed, γ > ∝ β −1/2 e ∝ d e up to at least β e = 10, in agreement with (3.2), and despite the width of the reconnecting layer being set by ρ e rather than d e . Therefore, we expect our conclusions to be at least qualitatively relevant at β e ∼ 1.…”

Section: Collisionless Tearing Modementioning

confidence: 56%

Disruption of Alfvénic turbulence by magnetic reconnection in a collisionless plasma

2017

View full text Add to dashboard Cite

We calculate the disruption scale λ D at which sheet-like structures in dynamically aligned Alfvénic turbulence are destroyed by the onset of magnetic reconnection in a low-β collisionless plasma. The scaling of λ D depends on the order of the statistics being considered, with more intense structures being disrupted at larger scales. The disruption scale for the structures that dominate the energy spectrum is4/9 , where d e is the electron inertial scale, ρ s is the ion sound scale, and L ⊥ is the outer scale of the turbulence. When β e and ρ s /L ⊥ are sufficiently small, the scale λ D is larger than ρ s and there is a break in the energy spectrum at λ D , rather than at ρ s . We propose that the fluctuations produced by the disruption are circularised flux ropes, which may have already been observed in the solar wind. We predict the relationship between the amplitude and radius of these structures and quantify the importance of the disruption process to the cascade in terms of the filling fraction of undisrupted structures and the fractional reduction of the energy contained in them at the ion sound scale ρ s . Both of these fractions depend strongly on β e , with the disrupted structures becoming more important at lower β e . Finally, we predict that the energy spectrum between λ D and ρ s is steeper than k −3 ⊥ , when this range exists. Such a steep "transition range" is sometimes observed in short intervals of solar-wind turbulence. The onset of collisionless magnetic reconnection may therefore significantly affect the nature of plasma turbulence around the ion gyroscale.

show abstract

Section: Collisionless Tearing Modementioning

confidence: 56%

Disruption of Alfvénic turbulence by magnetic reconnection in a collisionless plasma

2017

View full text Add to dashboard Cite

show abstract

“…Observationally, there have been attempts to measure the kinetic entropy or use entropic measures with satellite observations of, for example, Earth's magnetotail plasma sheet (Kaufmann & Paterson 2009, 2011), Earth's bow shock (Parks et al 2012), the near-Earth solar wind (Weck et al 2015;Olivier, Engelbrecht & Strauss 2019) and auroral currents (Osmane, Dimmock & Pulkkinen 2019). It has also been used in a number of theoretical and numerical studies (Montgomery & Nielson 1970;Hsu, Joyce & Montgomery 1974;Krommes & Hu 1994;Leubner 2004;Watanabe & Sugama 2004;Howes et al 2006;Sarazin et al 2009;Tatsuno et al 2009;Nariyuki 2011;Nakata, Watanabe & Sugama 2012;Loureiro, Schekochihin & Zocco 2013;TenBarge & Howes 2013;Numata & Loureiro 2015;Pezzi, Valentini & Veltri 2016;Grošelj et al 2017;Hesse et al 2017;Pezzi 2017;Cerri, Kunz & Califano 2018;Eyink 2018;Gary et al 2018;Kawazura, Barnes & Schekochihin 2019;Liang et al 2019;Pezzi et al 2019;Du et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Kinetic entropy-based measures of distribution function non-Maxwellianity: theory and simulations

et al. 2020

View full text Add to dashboard Cite

We investigate kinetic entropy-based measures of the non-Maxwellianity of distribution functions in plasmas, i.e. entropy-based measures of the departure of a local distribution function from an associated Maxwellian distribution function with the same density, bulk flow and temperature as the local distribution. First, we consider a form previously employed by Kaufmann & Paterson (J. Geophys. Res., vol. 114, 2009, A00D04), assessing its properties and deriving equivalent forms. To provide a quantitative understanding of it, we derive analytical expressions for three common non-Maxwellian plasma distribution functions. We show that there are undesirable features of this non-Maxwellianity measure including that it can diverge in various physical limits and elucidate the reason for the divergence. We then introduce a new kinetic entropy-based non-Maxwellianity measure based on the velocity-space kinetic entropy density, which has a meaningful physical interpretation and does not diverge. We use collisionless particle-in-cell simulations of two-dimensional anti-parallel magnetic reconnection to assess the kinetic entropy-based non-Maxwellianity measures. We show that regions of non-zero non-Maxwellianity are linked to kinetic processes occurring during magnetic reconnection. We also show the simulated non-Maxwellianity agrees reasonably well with predictions for distributions resembling those calculated analytically. These results can be important for applications, as non-Maxwellianity can be used to identify regions of kinetic-scale physics or increased dissipation in plasmas.

show abstract

“…Second, we also found smaller reconnection rates in the high beta case compared to the low beta one, in agreement with previous studies of gyrokinetic simulations of magnetic reconnection. 39,40 However, we can notice in Fig. 1 that the reconnection values for both low and high plasma β cases are still a substantial fraction of (dΨ/dt)/Ψ N ∼ 0.1.…”

Section: A Global Evolutionmentioning

confidence: 90%

Gyrokinetic and kinetic particle-in-cell simulations of guide-field reconnection. I. Macroscopic effects of the electron flows

et al. 2015

View full text Add to dashboard Cite

In this work, we compare gyrokinetic (GK) and fully kinetic Particle-in-Cell (PIC) simulations of magnetic reconnection in the limit of strong guide field. In particular, we analyze the limits of applicability of the GK plasma model compared to a fully kinetic description of force free current sheets for finite guide fields (b g ). Here we report the first part of an extended comparison, focusing on the macroscopic effects of the electron flows. For a low beta plasma (β i = 0.01), it is shown that both plasma models develop magnetic reconnection with similar features in the secondary magnetic islands if a sufficiently high guide field (b g 30) is imposed in the kinetic PIC simulations. Outside of these regions, in the separatrices close to the X points, the convergence between both plasma descriptions is less restrictive (b g 5). Kinetic PIC simulations using guide fields b g 30 reveal secondary magnetic islands with a core magnetic field and less energetic flows inside of them in comparison to the GK or kinetic PIC runs with stronger guide fields. We find that these processes are mostly due to an initial shear flow absent in the GK initialization and negligible in the kinetic PIC high guide field regime, in addition to fast outflows on the order of the ion thermal speed that violate the GK ordering. Since secondary magnetic islands appear after the reconnection peak time, a kinetic PIC/GK comparison is more accurate in the linear phase of magnetic reconnection. For a high beta plasma (β i = 1.0) where reconnection rates and fluctuations levels are reduced, similar processes happen in the secondary magnetic islands in the fully kinetic description, but requiring much lower guide fields (b g 3).

show abstract

Electron and Ion Heating During Magnetic Reconnection in Weakly Collisional Plasmas

Cited by 11 publications

References 13 publications

Disruption of Alfvénic turbulence by magnetic reconnection in a collisionless plasma

Disruption of Alfvénic turbulence by magnetic reconnection in a collisionless plasma

Kinetic entropy-based measures of distribution function non-Maxwellianity: theory and simulations

Gyrokinetic and kinetic particle-in-cell simulations of guide-field reconnection. I. Macroscopic effects of the electron flows

Contact Info

Product

Resources

About