Magnetic pumping model for energizing superthermal particles applied to observations of the Earth's bow shock

Lichko, Emily; Egedal, J.

doi:10.1038/s41467-020-16660-4

Cited by 24 publications

(42 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, this will lead to power-law solutions with (Montag et al 2017). The diffusion equation in (5.11) (as well as the similar form obtained in Lichko & Egedal (2020)) is, therefore, consistent with the power law distributions recorded in situ by spacecraft throughout the solar wind and the Earth's magnetosphere.…”

Section: Discussionsupporting

confidence: 86%

“…The results of the present paper can be considered an extension of the magnetic pumping model by Lichko & Egedal (2020). Here we uncover an additional heating mechanism, which is related to the particular effect of electrons becoming trapped/untrapped in magnetic mirror-structures that form in the presence of compressional wave dynamics.…”

Section: Introductionmentioning

confidence: 69%

“…Indicated by full lines, the theory is expected to be valid for . Red lines: for comparison the efficiency of magnetic pumping the red lines represent the similar in (6) of Lichko & Egedal (2020), evaluated with and , and considering the same magnetic perturbations as applied for the -mixing.…”

Section: Discussionmentioning

confidence: 98%

“…For comparison, the red lines in figure 5 are obtained from the model of magnetic pumping with trapped electrons developed in Lichko & Egedal (2020), where in (6) an expression is given for the form of due to magnetic pumping, and we evaluate for the same magnetic perturbations as yielded the blue lines in figure 5. Furthermore, in this comparison is obtained assuming .…”

Section: Discussionmentioning

confidence: 99%

“…Previous work on magnetic pumping (such as transit-time damping (Barnes 1966; Berger et al 1971; Stix 1992; Lichko et al 2017)), have largely concluded that pumping is not efficient for energizing superthermal electrons with . Meanwhile, the pumping models of Egedal et al (2018) and Lichko & Egedal (2020) include the effects of trapping and differs significantly from earlier results, as the trapping permits especially electrons with to become energized. Another interesting property that is in contrast to the turbulent cascade where the energy is transferred from large scales to small scales before being absorbed (Howes et al 2008; Sahraoui et al 2009), in magnetic pumping the energy is provided directly by the energy-rich largest-scale magnetic fluctuations.…”

Section: Introductionmentioning

confidence: 92%

See 4 more Smart Citations

Parallel velocity mixing yielding enhanced electron heating during magnetic pumping

2021

Self Cite

View full text Add to dashboard Cite

Magnetic wave perturbations are observed in the solar wind and in the vicinity of Earth's bow shock. For such environments, recent work on magnetic pumping with electrons trapped in the magnetic perturbations has demonstrated the possibility of efficient energization of superthermal electrons. Here we also analyse the energization of such energetic electrons for which the transit time through the system is short compared with time scales associated with the magnetic field evolution. In particular, considering an idealized magnetic configuration we show how trapping/detrapping of energetic magnetized electrons can cause effective parallel velocity ( $v_{\parallel }$ -) diffusion. This parallel diffusion, combined with naturally occurring mechanisms known to cause pitch angle scattering, such as whistler waves, produces enhanced heating rates for magnetic pumping. We find that at low pitch angle scattering rates, the combined mechanism enhances the heating beyond the predictions of the recent theory for magnetic pumping with trapped electrons.

show abstract

Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

See 3 more Smart Citations

Parallel velocity mixing yielding enhanced electron heating during magnetic pumping

2021

Self Cite

View full text Add to dashboard Cite

show abstract

Evaluating the de Hoffmann-Teller cross-shock potential at real collisionless shocks

Schwartz

Ergun

Kucharek

et al. 2021

Preprint

View full text Add to dashboard Cite

Shock waves are common in the heliosphere and beyond. The collisionless nature of most astrophysical plasmas allows for the energy processed by shocks to be partitioned amongst particle sub-populations and electromagnetic fields via physical mechanisms that are not well understood. The electrostatic potential across such shocks is frame dependent. In a frame where the incident bulk velocity is parallel to the magnetic field, the deHoffmann-Teller frame, the potential is linked directly to the ambipolar electric field established by the electron pressure gradient. Thus measuring and understanding this potential solves the electron partition problem, and gives insight into other competing shock processes. Integrating measured electric fields is space is problematic since the measurements can have offsets that change with plasma conditions. The offsets, once integrated, can be as large or larger than the shock potential. Here we exploit the high-quality field and plasma measurements from NASA's Magnetospheric Multiscale mission to attempt this calculation. We investigate recent adaptations of the deHoffmann-Teller frame transformation to include time variability, and conclude that in practise these face difficulties inherent in the 3D time-dependent nature of real shocks by comparison to 1D simulations. Potential estimates based on electron fluid and kinetic analyses provide the most robust measures of the deHoffmann-Teller potential, but with some care direct integration of the electric fields can be made to agree. These results suggest that it will be difficult to independently assess the role of other processes, such as scattering by shock turbulence, in accounting for the electron heating.

show abstract

Evaluating the de Hoffmann-Teller cross-shock potential at real collisionless shocks

Schwartz

Ergun

Kucharek

et al. 2021

Preprint

View full text Add to dashboard Cite

Magnetic pumping model for energizing superthermal particles applied to observations of the Earth's bow shock

Cited by 24 publications

References 32 publications

Parallel velocity mixing yielding enhanced electron heating during magnetic pumping

Parallel velocity mixing yielding enhanced electron heating during magnetic pumping

Evaluating the de Hoffmann-Teller cross-shock potential at real collisionless shocks

Evaluating the de Hoffmann-Teller cross-shock potential at real collisionless shocks

Contact Info

Product

Resources

About