Simulation Study on an Intense Current Flow in a High Density Plasma T. Taguchi (Setsunan University), K. Mima, and T. M. Antonsen Relativistic electron beam transport has been studied using a newly developed three dimensional hybrid code, which treats the beam electrons as a kinetic particles while background plasmas, ions and electrons, are described as fluids. As electrons injected from a boundary propagate through the high density region, they produce a large current flow along the propagation. Self-consistent analysis shows that the induced strong magnetic field tears the initially solid beam and generates a lot of small size beamlets. However, the small beams attract each other by the mutual current force, and finally collapse into a single beam. This breakup and merging processes are closely related to the anomalous resistivity in the high density plasma.