Magnetic Field Amplification by a Nonlinear Electron Streaming Instability

• Published in: Physical review letters Vol. 126; no. 21; p. 215101
• Main Authors: Peterson, J. R., Glenzer, S., Fiuza, F.
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 26-05-2021; American Physical Society (APS)
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Amplification; Electron beams; Electrons; Field strength; Filaments; Kinetic energy; Magnetic fields; Magnetohydrodynamic stability; Relativistic effects; Saturation; Stability analysis; streaming instabilities, magnetic field generation, high-energy-density plasmas, astrophysical plasmas; Weibel instability
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.126.215101

Magnetic field amplification by relativistic streaming plasma instabilities is central to a wide variety of high-energy astrophysical environments as well as to laboratory scenarios associated with intense lasers and electron beams. We report on a new secondary nonlinear instability that arises for relativistic dilute electron beams after the saturation of the linear Weibel instability. This instability grows due to the transverse magnetic pressure associated with the beam current filaments, which cannot be quickly neutralized due to the inertia of background ions. We show that it can amplify the magnetic field strength and spatial scale by orders of magnitude, leading to large-scale plasma cavities with strong magnetic field and to very efficient conversion of the beam kinetic energy into magnetic energy. The instability growth rate, saturation level, and scale length are derived analytically and shown to be in good agreement with fully kinetic simulations.