Multi-scale simulations of plasma with iPIC3D

The nonlinear evolution of collisionless plasmas is typically a multi-scale process where the energy is injected at large, fluid scales and dissipated at small, kinetic scales. Accurately modelling the global evolution requires to take into account the main micro-scale physical processes of interest. This is why comparison of different plasma models is today an imperative task aiming at understanding cross-scale processes in plasmas. We report here the first comparative study of the evolution of a magnetized shear flow, through a variety of different plasma models by using magnetohydrodynamic, Hall-MHD, two-fluid, hybrid kinetic and full kinetic codes. Kinetic relaxation effects are discussed to emphasize the need for kinetic equilibriums to study the dynamics of collisionless plasmas in non trivial configurations. Discrepancies between models are studied both in the linear and in the nonlinear regime of the magnetized Kelvin-Helmholtz instability, to highlight the effects of small scale processes on the nonlinear evolution of collisionless plasmas. We illustrate how the evolution of a magnetized shear flow depends on the relative orientation of the fluid vorticity with respect to the magnetic field direction during the linear evolution when kinetic effects are taken into account. Even if we found that small scale processes differ between the different models, we show that the feedback from small, kinetic scales to large, fluid scales is negligable in the nonlinear regime. This study show that the kinetic modeling validates the use of a fluid approach at large scales, which encourages the development and use of fluid codes to study the nonlinear evolution of magnetized fluid flows, even in the colisionless regime.

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“…iPIC3D is a fully kinetic, fully electromagnetic Particle-in-Cell code 33 . It implements the moment implicit method 34 .…”

Section: Full Pic Codementioning

confidence: 99%

Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

et al. 2013

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“…The simulation of collisionless plasma was carried out using fully kinetic electromagnetic PIC code with implicit time stepping iPic3D (Markidis et al 2010). The simulation domain representing a cubic box of size 20 × 20 × 20 d i (where d i = c/ω pi is ion iner-tial length) has 400 3 cells with 27 particle of each specie per cell.…”

Section: Simulation Setupmentioning

confidence: 99%

Role of Z-pinches in magnetic reconnection in space plasmas

2014

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A widely accepted scenario of magnetic reconnection in collisionless space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is commonly studied in pinches, current channels embedded into twisted magnetic fields. No model of magnetic reconnection in space plasmas considers both null-points and pinches as peers. We have performed a particle-in-cell simulation of magnetic reconnection in a three-dimensional configuration where null-points are present initially, and Z-pinches are formed during the simulation along the lines of spiral null-points. The non-spiral nullpoints are more stable than spiral ones, and no substantial energy dissipation is associated with them. On the contrary, turbulent magnetic reconnection in the pinches causes the magnetic energy to decay at a rate of ∼ 1.5% per ion gyro period. Dissipation in similar structures is a likely scenario in space plasmas with large fraction of spiral null-points.

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“…The boundaries are periodic in the x and z directions, while are perfect conductor and reflecting boundary conditions for fields and particles respectively in the y direction. Simulations are carried out with the parallel implicit Particle-in-Cell iPIC3D code [26].…”

Section: Simulation Set-upmentioning

confidence: 99%

Three dimensional density cavities in guide field collisionless magnetic reconnection

Lapenta

Divin

Goldman³

et al. 2012

Physics of Plasmas

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Particle-in-Cell simulations of collisionless magnetic reconnection with a guide field reveal for the first time the three dimensional features of the low density regions along the magnetic reconnection separatrices, the so-called cavities. It is found that structures with further lower density develop within the cavities. Because their appearance is similar to the rib shape, these formations are here called low density ribs. Their location remains approximately fixed in time and their density progressively decreases, as electron currents along the cavities evacuate them. They develop along the magnetic field lines and are supported by a strong perpendicular electric field that oscillates in space. In addition, bipolar parallel electric field structures form as isolated spheres between the cavities and the outflow plasma, along the direction of the low density ribs and of magnetic field lines.

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Multi-scale simulations of plasma with iPIC3D

Cited by 303 publications

References 24 publications

Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

Nonlinear evolution of the magnetized Kelvin-Helmholtz instability: From fluid to kinetic modeling

Role of Z-pinches in magnetic reconnection in space plasmas

Three dimensional density cavities in guide field collisionless magnetic reconnection

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