Hybrid guiding-centre/full-orbit simulations in non-axisymmetric magnetic geometry exploiting general criterion for guiding-centre accuracy

Pfefferlé, David; Graves, J. P.; Cooper, W. A.

doi:10.1088/0741-3335/57/5/054017

Cited by 14 publications

(29 citation statements)

References 19 publications

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“…where the field-dependent quantities referenced on the right-hand side of the equation are evaluated at position R n GC . This method of switching between the two test particle trajectory formulations is similar to those used elsewhere (e.g., Kress et al, 2008;Pfefferlé et al, 2015;Snicker et al, 2010;Sorathia et al, 2017).…”

Section: A1 Test Particle Integrationmentioning

confidence: 99%

Modeling the Depletion and Recovery of the Outer Radiation Belt During a Geomagnetic Storm: Combined MHD and Test Particle Simulations

et al. 2018

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During geomagnetic storms the intensities of the outer radiation belt electron population can exhibit dramatic variability. Deep depletions in intensity during the main phase are followed by increases during the recovery phase, often to levels that significantly exceed their prestorm values. To study these processes, we simulate the evolution of the outer radiation belt during the 17 March 2013 geomagnetic storm using our newly developed radiation belt model (Conservative Hamiltonian Integrator for Magnetospheric Particles) based on test particle and coupled 3‐D ring current and global magnetohydrodynamic (MHD) simulations, and driven solely with solar wind and F10.7 flux data. Our approach differs from previous work in that we use MHD information to identify regions of strong, bursty, and azimuthally localized earthward convection in the magnetotail where test particles are then seeded. We validate our model using in situ Van Allen Probe electron intensities over a multiday period and show that our model is able to reproduce meaningful qualitative and quantitative agreement. Analysis of our model enables us to study the processes that govern the transition from the prestorm to poststorm outer belt. Our analysis demonstrates that during the early main phase of the storm the preexisting outer belt is largely wiped out via magnetopause losses, and subsequently, a new outer belt is created during a handful of discrete, mesoscale injections. Finally, we demonstrate the potential importance of magnetic gradient trapping in the transport and energization of outer belt electrons using a controlled numerical experiment.

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Section: A1 Test Particle Integrationmentioning

confidence: 99%

Modeling the Depletion and Recovery of the Outer Radiation Belt During a Geomagnetic Storm: Combined MHD and Test Particle Simulations

et al. 2018

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“…The nonadiabatic motion of charged particles in highly curved magnetic fields has been previously studied (Birmingham, 1984;Buchner & Zelenyi, 1989;Chen, 1992;Chirkov, 1978;Hudson et al, 1997;Speiser, 1991;Young et al, 2002;Engel et al, 2016). Nonadiabatic motion of particles can also exist in sheared magnetic fields (Smets, 2000;Pfefferle et al, 2015) or for short scale length Northrop (1963). Most of the study of chaotic motion was for the highly stretched field of the magnetotail.…”

Section: Chaotic Electron Motionmentioning

confidence: 99%

Simulations of Electron Energization and Injection by BBFs Using High‐Resolution LFM MHD Fields

et al. 2019

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We study electron injection and energization by bursty bulk flows (BBFs), by tracing electron trajectories using magnetohydrodynamic (MHD) field output from the Lyon‐Fedder‐Mobarry (LFM) code. The LFM MHD simulations were performed using idealized solar wind conditions to produce BBFs. We show that BBFs can inject energetic electrons of few to 100 keV from the magnetotatail beyond −24 RE to inward of geosynchronous, while accelerating them in the process. We also show the dependence of energization and injection on the initial relative position of the electrons to the magnetic field structure of the BBF, the initial pitch angle, and the initial energy. In addition, we have shown that the process can be nonadiabatic with violation of the first adiabatic invariant (μ). Further, we discuss the mechanism of energization and injection in order to give generalized insight into the process.

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“…In this setting we can exhibit some potentially physical relevant effect beyond gyrokinetic or guiding center reductions. For instance, Recently Pfefferlé et al 7 have found that there exists a case where the full trajectory and the trajectory obtained from guiding center reduction are completely different from each other even though the gradient of the magnetic field is 0. In the same vein, Cambon et al 6 study the full orbit effects of charged particle motion in a mag-netic field in toroidal and cylindrical geometry without any assumptions of invariance of the magnetic moment.…”

Section: Introductionmentioning

confidence: 99%

Full particle orbit effects in regular and stochastic magnetic fields

et al. 2016

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1We present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present the particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e. fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The nonmonotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the qprofile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. We show that a similar but more complex scenario appears in the case of particle orbits that depends in a non-trivial way on the energy and pitch angle of the particles. a) Electronic

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Hybrid guiding-centre/full-orbit simulations in non-axisymmetric magnetic geometry exploiting general criterion for guiding-centre accuracy

Cited by 14 publications

References 19 publications

Modeling the Depletion and Recovery of the Outer Radiation Belt During a Geomagnetic Storm: Combined MHD and Test Particle Simulations

Modeling the Depletion and Recovery of the Outer Radiation Belt During a Geomagnetic Storm: Combined MHD and Test Particle Simulations

Simulations of Electron Energization and Injection by BBFs Using High‐Resolution LFM MHD Fields

Full particle orbit effects in regular and stochastic magnetic fields

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