Magnetic field generation during the collision of narrow plasma clouds

We investigate the dynamics of the collision of narrow plasma clouds, whose transverse dimension is on the order of the electron skin depth. A 2D3V (t wo dimensions in space and three dimensions in velocity space) particle-in- cell (PIC) collisionless relativistic code is used to show the generation o f a quasi-static magnetic field during the collision of narrow plasma cloud s both in electron-ion and electron-positron (pair) plasmas. The localized strong magnetic fluxes result in the generation of the charge separation wi th complicated structures, which may be sources of electromagnetic as well as Langmuir waves. We also present one application of this process, which o ccurs during coalescence of magnetic islands in a current sheet of pair pla smas.