Dynamics of a Self-Consistent Magnetic Field and Diffusive Scattering of Ions in a Plasma with Strong Thermal Anisotropy

We numerically simulate the nonlinear phase of the Weibel instability of a two-component plasma with strong thermal anisotropy and comparable energies of the electron and ion fractions. Spatiotemporal dynamics of the current filaments and the magnetic field created by the electrons or ions is analyzed. It is found that the magnetic field resulting from the electron instability leads to the scattering of ions, decreasing the degree of their momentum distribution anisotropy and suppressing the development of the ion instability. It is shown that the long-term maintenance and evolution of a large-scale quasi-stationary magnetic field are due to the ion currents which are induced by the decaying magnetic field and start to dominate the electrons with time. The possibility of the considered scenario of the Weibel instability in a nonequilibrium laser-produced plasma is discussed.