This study explores the dynamics and structural evolution of high-density plasma beams as they propagate through a lower-density plasma medium, utilizing relativistic kinetic particle-in-cell simulations. The width of the incident plasma beam governs the morphological evolution of jet structures and shock formation. When the beam width is smaller than the ion skin depth, the reduced electron–ion charge separation leads to insufficient magnetic pressure for shock development. Conversely, when the beam width exceeds the ion skin depth, the enhanced magnetic pressure drives shock formation. Moreover, when the beam width exceeds the ion cyclotron radius, the jet density structures are determined by the beam-width-to-ion-cyclotron-radius ratio through the magnetic field configuration.
This study explores how high-density plasma beams evolve as they move through a lower-density plasma. The beam width determines if jets and shocks form - narrower beams lack enough magnetic pressure for shocks, while wider beams can drive shock formation.