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Title: Fully Kinetic Large-scale Simulations of the Collisionless Magnetorotational Instability

Abstract

We present two-dimensional particle-in-cell simulations of the fully kinetic collisionless magnetorotational instability (MRI) in weakly magnetized (high β) pair plasma. The central result of this numerical analysis is the emergence of a self-induced turbulent regime in the saturation state of the collisionless MRI, which can only be captured for large enough simulation domains. One of the underlying mechanisms for the development of this turbulent state is the drift-kink instability (DKI) of the current sheets resulting from the nonlinear evolution of the channel modes. The onset of the DKI can only be observed for simulation domain sizes exceeding several linear MRI wavelengths. The DKI and ensuing magnetic reconnection activate the turbulent motion of the plasma in the late stage of the nonlinear evolution of the MRI. At steady-state, the magnetic energy has an MHD-like spectrum with a slope of k –5/3 for kρ < 1 and k –3 for sub-Larmor scale (kρ > 1). We also examine the role of the collisionless MRI and associated magnetic reconnection in the development of pressure anisotropy. We study the stability of the system due to this pressure anisotropy, observing the development of mirror instability during the early-stage of the MRI. We further discuss themore » importance of magnetic reconnection for particle acceleration during the turbulence regime. Furthermore, consistent with reconnection studies, we show that at late times the kinetic energy presents a characteristic slope of ϵ –2 in the high-energy region.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [2]
  1. Univ. de Lisboa, Lisboa (Portugal); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Univ. de Lisboa, Lisboa (Portugal)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  4. Univ. de Lisboa, Lisboa (Portugal); DCTI/ISCTE Instituto Univ. de Lisboa, Lisboa (Portugal)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1542025
Grant/Contract Number:  
FG02-91ER54109
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 859; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy & Astrophysics; accretion; accretion disks; instabilities; magnetic reconnection; plasmas; turbulence

Citation Formats

Inchingolo, Giannandrea, Grismayer, Thomas, Loureiro, Nuno F., Fonseca, Ricardo A., and Silva, Luis O. Fully Kinetic Large-scale Simulations of the Collisionless Magnetorotational Instability. United States: N. p., 2018. Web. doi:10.3847/1538-4357/aac0f2.
Inchingolo, Giannandrea, Grismayer, Thomas, Loureiro, Nuno F., Fonseca, Ricardo A., & Silva, Luis O. Fully Kinetic Large-scale Simulations of the Collisionless Magnetorotational Instability. United States. doi:10.3847/1538-4357/aac0f2.
Inchingolo, Giannandrea, Grismayer, Thomas, Loureiro, Nuno F., Fonseca, Ricardo A., and Silva, Luis O. Mon . "Fully Kinetic Large-scale Simulations of the Collisionless Magnetorotational Instability". United States. doi:10.3847/1538-4357/aac0f2. https://www.osti.gov/servlets/purl/1542025.
@article{osti_1542025,
title = {Fully Kinetic Large-scale Simulations of the Collisionless Magnetorotational Instability},
author = {Inchingolo, Giannandrea and Grismayer, Thomas and Loureiro, Nuno F. and Fonseca, Ricardo A. and Silva, Luis O.},
abstractNote = {We present two-dimensional particle-in-cell simulations of the fully kinetic collisionless magnetorotational instability (MRI) in weakly magnetized (high β) pair plasma. The central result of this numerical analysis is the emergence of a self-induced turbulent regime in the saturation state of the collisionless MRI, which can only be captured for large enough simulation domains. One of the underlying mechanisms for the development of this turbulent state is the drift-kink instability (DKI) of the current sheets resulting from the nonlinear evolution of the channel modes. The onset of the DKI can only be observed for simulation domain sizes exceeding several linear MRI wavelengths. The DKI and ensuing magnetic reconnection activate the turbulent motion of the plasma in the late stage of the nonlinear evolution of the MRI. At steady-state, the magnetic energy has an MHD-like spectrum with a slope of k –5/3 for kρ < 1 and k –3 for sub-Larmor scale (kρ > 1). We also examine the role of the collisionless MRI and associated magnetic reconnection in the development of pressure anisotropy. We study the stability of the system due to this pressure anisotropy, observing the development of mirror instability during the early-stage of the MRI. We further discuss the importance of magnetic reconnection for particle acceleration during the turbulence regime. Furthermore, consistent with reconnection studies, we show that at late times the kinetic energy presents a characteristic slope of ϵ –2 in the high-energy region.},
doi = {10.3847/1538-4357/aac0f2},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 859,
place = {United States},
year = {2018},
month = {6}
}

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