Evolution of the Weibel instability in relativistically hot electron--positron plasmas

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870498· OSTI ID:7240830

Yang, T B; Arons, J ^[1]; Langdon, A B ^[2]

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1. Theoretical Astrophysics Center, University of California at Berkeley, 601 Campbell Hall, Berkeley, California 94720 (United States)
2. X-Division, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

Analytical and numerical studies of the evolution of the Weibel instability in relativistically hot electron--positron plasmas are presented. Appropriate perturbations on the electromagnetic fields and the particle orbits, corresponding to a single unstable mode, are determined analytically and used as initial conditions in the numerical simulations to excite a single unstable mode. A simple estimate of the saturation amplitude is also obtained analytically. Numerical simulations are carried out when a single unstable mode is favorably excited. Comparisons of the simulation results with the analytical ones show very good agreement. Also observed in the simulations are mode competition, mode suppression, and the difference in the long-term evolution between the magnetized and unmagnetized plasmas. For relativistic unmagnetized plasmas, energy-like global constraints, which are conservation laws in addition to the conservation of energy and momentum, are derived. Numerical simulations of the multimode evolution are described. Simulation results show growth in electromagnetic energy in the early stage, a narrowing in the bandwidth and a shift in the peak of the spectrum to longer wavelength in the subsequent evolution, and a decrease in the temperature anisotropy. In a simulation for an unmagnetized plasma, it is observed that the system reaches a steady state halfway through the simulation. In contrast, the peak of the spectrum continues to shift to lower wave number [ital k], and the temperature anisotropy continues to decrease during the entire simulation for a magnetized plasma.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7240830
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:9; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

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