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Title: Oblique Alfvén instabilities driven by compensated currents

Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfvénic instability driven by compensated currents flowing along the background magnetic field. Because of the vastly different electron and ion gyroradii, oblique Alfvénic perturbations react differently on the currents carried by the hot ion beams and the return electron currents. Ultimately, this difference leads to a non-resonant aperiodic instability at perpendicular wavelengths close to the beam ion gyroradius. The instability growth rate increases with increasing beam current and temperature. In the solar wind upstream of Earth's bow shock, the instability growth time can drop below 10 proton cyclotron periods. Our results suggest that this instability can contribute to the turbulence and ion acceleration in space and astrophysical foreshocks.
Authors:
 [1] ; ;  [2]
  1. Main Astronomical Observatory, NASU, Kyiv (Ukraine)
  2. Solar-Terrestrial Centre of Excellence, Space Physics Division, Belgian Institute for Space Aeronomy, Ringlaan-3-Avenue Circulaire, B-1180 Brussels (Belgium)
Publication Date:
OSTI Identifier:
22348205
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ALFVEN WAVES; ASTROPHYSICS; BEAM CURRENTS; DISTURBANCES; INSTABILITY GROWTH RATES; ION BEAMS; MAGNETIC FIELDS; PERTURBATION THEORY; PLASMA; PROTONS; SHOCK WAVES; SOLAR WIND; SPACE; SUPERNOVA REMNANTS; TAIL IONS; TURBULENCE; WAVELENGTHS