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Title: Ion velocity distribution at the termination shock: 1-D PIC simulation

Abstract

The Voyager 2 (V2) plasma observations of the proton temperature downstream of the quasi-perpendicular heliospheric termination shock (TS) showed that upstream thermal solar wind ions played little role in the shock dissipation mechanism and their downstream temperature is an order of magnitude smaller than predicted by MHD Rankine-Hugoniot conditions. While pickup ions (PUI) are generally expected to play an important role in energy dissipation at the shock, the details remain unclear. Here, one-dimensional (1-D) Particle-in-cell (PIC) code is used to examine kinetic properties and downstream velocity distribution functions of pickup ions (the hot supra-thermal component) and solar wind protons (SWs, the cold component) at the perpendicular heliospheric termination shock. The code treats the pickup ions self-consistently as a third component. Present results show that: (1) both of the incident SWs and PUIs can be separated into two parts: reflected (R) ions and directly transmitted (DT) ions, the energy gain of the R ions at the shock front is much larger than that of the DT ions; (2) the fraction of reflected SWs and their downstream temperature decrease with the relative percentage PUI%; (3) no matter how large the PUI% is, the downstream ion velocity distribution function always can be separatedmore » into three parts: 1. a high energy tail (i.e. the wings) dominated by the reflected PUIs, 2. a low energy core mainly contributed by the directly transmitted SWs, and 3. a middle energy part which is a complicated superposition of reflected SWs and directly transmitted PUIs. The significance of the presence of pickup ions on shock front micro-structure and nonstationarity is also discussed.« less

Authors:
; ;  [1];  [2]
  1. CAS Key Laboratory of Basic Plasma Physics, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)
  2. France
Publication Date:
OSTI Identifier:
22075837
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1500; Journal Issue: 1; Conference: 11. annual international astrophysics conference, Palm Springs, CA (United States), 19-23 Mar 2012; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; DISTRIBUTION FUNCTIONS; ELECTRON TEMPERATURE; ENERGY LOSSES; HELIOSPHERE; ION TEMPERATURE; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA SIMULATION; PROTON TEMPERATURE; RANKINE-HUGONIOT EQUATIONS; SHOCK WAVES; SOLAR PROTONS; SOLAR WIND; VOYAGER SPACE PROBES

Citation Formats

Quanming, Lu, Zhongwei, Yang, Lembege, Bertrand, SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, and LATMOS-UVSQ-IPSL-CNRS, Guyancourt 78280. Ion velocity distribution at the termination shock: 1-D PIC simulation. United States: N. p., 2012. Web. doi:10.1063/1.4768773.
Quanming, Lu, Zhongwei, Yang, Lembege, Bertrand, SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, & LATMOS-UVSQ-IPSL-CNRS, Guyancourt 78280. Ion velocity distribution at the termination shock: 1-D PIC simulation. United States. https://doi.org/10.1063/1.4768773
Quanming, Lu, Zhongwei, Yang, Lembege, Bertrand, SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, and LATMOS-UVSQ-IPSL-CNRS, Guyancourt 78280. 2012. "Ion velocity distribution at the termination shock: 1-D PIC simulation". United States. https://doi.org/10.1063/1.4768773.
@article{osti_22075837,
title = {Ion velocity distribution at the termination shock: 1-D PIC simulation},
author = {Quanming, Lu and Zhongwei, Yang and Lembege, Bertrand and SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136 and LATMOS-UVSQ-IPSL-CNRS, Guyancourt 78280},
abstractNote = {The Voyager 2 (V2) plasma observations of the proton temperature downstream of the quasi-perpendicular heliospheric termination shock (TS) showed that upstream thermal solar wind ions played little role in the shock dissipation mechanism and their downstream temperature is an order of magnitude smaller than predicted by MHD Rankine-Hugoniot conditions. While pickup ions (PUI) are generally expected to play an important role in energy dissipation at the shock, the details remain unclear. Here, one-dimensional (1-D) Particle-in-cell (PIC) code is used to examine kinetic properties and downstream velocity distribution functions of pickup ions (the hot supra-thermal component) and solar wind protons (SWs, the cold component) at the perpendicular heliospheric termination shock. The code treats the pickup ions self-consistently as a third component. Present results show that: (1) both of the incident SWs and PUIs can be separated into two parts: reflected (R) ions and directly transmitted (DT) ions, the energy gain of the R ions at the shock front is much larger than that of the DT ions; (2) the fraction of reflected SWs and their downstream temperature decrease with the relative percentage PUI%; (3) no matter how large the PUI% is, the downstream ion velocity distribution function always can be separated into three parts: 1. a high energy tail (i.e. the wings) dominated by the reflected PUIs, 2. a low energy core mainly contributed by the directly transmitted SWs, and 3. a middle energy part which is a complicated superposition of reflected SWs and directly transmitted PUIs. The significance of the presence of pickup ions on shock front micro-structure and nonstationarity is also discussed.},
doi = {10.1063/1.4768773},
url = {https://www.osti.gov/biblio/22075837}, journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1500,
place = {United States},
year = {Tue Nov 20 00:00:00 EST 2012},
month = {Tue Nov 20 00:00:00 EST 2012}
}