Magnetic field generation during the collision of electron-ion plasma clouds

We present the results of analytical studies and computer simulations of electron-ion plasma cloud collisions using 2D3V particle-in-cell and 2D two-fluid collisionless relativistic codes. We address the problem covering the generation of a quasistatic magnetic field. Using relativistic two-fluid equations for the two counterstreaming electron populations: we show with the help of linear theory that the generation of a magnetic field can be associated with the "electromagnetic counterstreaming instability". Two-dimensional (2D) particle-in-cell provide good agreement with the results of linear theory. We show that the quasistatic magnetic field undergoes a collisionless change of structure, leading to large-scale, long-lived structures. These processes may be important for the understanding of magnetic field generation in laser plasmas and in space plasmas in the regions where two stellar winds collide.