Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma
We study with a 3D particle-in-cell simulation discontinuities between an electron–positron pair plasma and magnetized electrons and protons. A pair plasma is injected at one simulation boundary with a speed 0.6 c along its normal. It expands into an electron-proton plasma and a magnetic field that...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2023-01-01
|
| Series: | New Journal of Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1367-2630/acdd19 |
| _version_ | 1797748602134593536 |
|---|---|
| author | M E Dieckmann D Folini M Falk A Bock P Steneteg R Walder |
| author_facet | M E Dieckmann D Folini M Falk A Bock P Steneteg R Walder |
| author_sort | M E Dieckmann |
| collection | DOAJ |
| description | We study with a 3D particle-in-cell simulation discontinuities between an electron–positron pair plasma and magnetized electrons and protons. A pair plasma is injected at one simulation boundary with a speed 0.6 c along its normal. It expands into an electron-proton plasma and a magnetic field that points orthogonally to the injection direction. Diamagnetic currents expel the magnetic field from within the pair plasma and pile it up in front of it. It pushes electrons, which induces an electric field pulse ahead of the magnetic one. This initial electromagnetic pulse (EMP) confines the pair plasma magnetically and accelerates protons electrically. The fast flow of the injected pair plasma across the protons behind the initial EMP triggers the filamentation instability. Some electrons and positrons cross the injection boundary and build up a second EMP. Electron-cyclotron drift instabilities perturb the plasma ahead of both EMPs seeding a Rayleigh–Taylor (RT)-type instability. Despite equally strong perturbations ahead of both EMPs, the second EMP is much more stable than the initial one. We attribute the rapid collapse of the initial EMP to the filamentation instability, which perturbed the plasma behind it. The RT-type instability transforms the planar EMPs into transition layers, in which magnetic flux ropes and electrostatic forces due to uneven numbers of electrons and positrons slow down and compress the pair plasma and accelerate protons. In our simulation, the expansion speed of the pair cloud decreased by about an order of magnitude and its density increased by the same factor. Its small thickness implies that it is capable of separating a relativistic pair outflow from an electron-proton plasma, which is essential for collimating relativistic jets of pair plasma in collisionless astrophysical plasma. |
| first_indexed | 2024-03-12T16:08:07Z |
| format | Article |
| id | doaj.art-04d24710509143909b38e419ff939cab |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:08:07Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-04d24710509143909b38e419ff939cab2023-08-09T14:15:34ZengIOP PublishingNew Journal of Physics1367-26302023-01-0125606301710.1088/1367-2630/acdd19Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasmaM E Dieckmann0D Folini1M Falk2A Bock3P Steneteg4R Walder5Department of Science and Technology (ITN), Linköping University, Campus Norrköping , SE-60174 Norrköping, SwedenUniv Lyon, ENS de Lyon, Univ Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574 F-69230 Saint-Genis-Laval, FranceDepartment of Science and Technology (ITN), Linköping University, Campus Norrköping , SE-60174 Norrköping, SwedenDepartment of Science and Technology (ITN), Linköping University, Campus Norrköping , SE-60174 Norrköping, SwedenDepartment of Science and Technology (ITN), Linköping University, Campus Norrköping , SE-60174 Norrköping, SwedenUniv Lyon, ENS de Lyon, Univ Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574 F-69230 Saint-Genis-Laval, FranceWe study with a 3D particle-in-cell simulation discontinuities between an electron–positron pair plasma and magnetized electrons and protons. A pair plasma is injected at one simulation boundary with a speed 0.6 c along its normal. It expands into an electron-proton plasma and a magnetic field that points orthogonally to the injection direction. Diamagnetic currents expel the magnetic field from within the pair plasma and pile it up in front of it. It pushes electrons, which induces an electric field pulse ahead of the magnetic one. This initial electromagnetic pulse (EMP) confines the pair plasma magnetically and accelerates protons electrically. The fast flow of the injected pair plasma across the protons behind the initial EMP triggers the filamentation instability. Some electrons and positrons cross the injection boundary and build up a second EMP. Electron-cyclotron drift instabilities perturb the plasma ahead of both EMPs seeding a Rayleigh–Taylor (RT)-type instability. Despite equally strong perturbations ahead of both EMPs, the second EMP is much more stable than the initial one. We attribute the rapid collapse of the initial EMP to the filamentation instability, which perturbed the plasma behind it. The RT-type instability transforms the planar EMPs into transition layers, in which magnetic flux ropes and electrostatic forces due to uneven numbers of electrons and positrons slow down and compress the pair plasma and accelerate protons. In our simulation, the expansion speed of the pair cloud decreased by about an order of magnitude and its density increased by the same factor. Its small thickness implies that it is capable of separating a relativistic pair outflow from an electron-proton plasma, which is essential for collimating relativistic jets of pair plasma in collisionless astrophysical plasma.https://doi.org/10.1088/1367-2630/acdd19plasma discontinuityRayleigh–Taylor instabilitymagnetic flux ropespair plasmaPIC simulationastrophysical jet |
| spellingShingle | M E Dieckmann D Folini M Falk A Bock P Steneteg R Walder Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma New Journal of Physics plasma discontinuity Rayleigh–Taylor instability magnetic flux ropes pair plasma PIC simulation astrophysical jet |
| title | Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma |
| title_full | Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma |
| title_fullStr | Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma |
| title_full_unstemmed | Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma |
| title_short | Three-dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron-proton plasma |
| title_sort | three dimensional structure and stability of discontinuities between unmagnetized pair plasma and magnetized electron proton plasma |
| topic | plasma discontinuity Rayleigh–Taylor instability magnetic flux ropes pair plasma PIC simulation astrophysical jet |
| url | https://doi.org/10.1088/1367-2630/acdd19 |
| work_keys_str_mv | AT medieckmann threedimensionalstructureandstabilityofdiscontinuitiesbetweenunmagnetizedpairplasmaandmagnetizedelectronprotonplasma AT dfolini threedimensionalstructureandstabilityofdiscontinuitiesbetweenunmagnetizedpairplasmaandmagnetizedelectronprotonplasma AT mfalk threedimensionalstructureandstabilityofdiscontinuitiesbetweenunmagnetizedpairplasmaandmagnetizedelectronprotonplasma AT abock threedimensionalstructureandstabilityofdiscontinuitiesbetweenunmagnetizedpairplasmaandmagnetizedelectronprotonplasma AT psteneteg threedimensionalstructureandstabilityofdiscontinuitiesbetweenunmagnetizedpairplasmaandmagnetizedelectronprotonplasma AT rwalder threedimensionalstructureandstabilityofdiscontinuitiesbetweenunmagnetizedpairplasmaandmagnetizedelectronprotonplasma |