Amplification of perpendicular and parallel magnetic fields by cosmic ray currents

Understand

Cosmic ray (CR) currents through magnetised plasma drive strong instabilities producing amplification of the magnetic field.

• This amplification helps explain the CR energy spectrum as well as observations of supernova remnants and radio galaxy hot spots.
• Using magnetohydrodynamic (MHD) simulations, we study the behaviour of the non-resonant hybrid (NRH) instability (also known as the Bell instability) in the case of CR currents perpendicular and parallel to the initial magnetic field.
• We demonstrate that extending simulations of the perpendicular case to 3D reveals a different character to the turbulence from that observed in 2D.