Laboratory model of magnetosphere created by strong plasma perturbation with frozen-in magnetic field

Abstract: Transient interaction of magnetic dipole with plasma flow carrying southward magnetic field is studied in laboratory experiment. The flow with transverse frozen-in field is generated by means of laser-produced plasma cross-field expansion into background plasma which fills vacuum chamber along externally applied magnetic field prior to interaction. Probe measurements showed that at realized plasma parameters effective collisionless Larmor coupling takes place resulting in formation of strong compressive perturbation which propagates in background with super-Alfvenic velocity and generates in laboratory frame transverse electric field comparable in value to expected induction one. Compression pulse with southward field after short propagation interacts with dipole and creates well defined magnetosphere. Comparison of magnetospheres created by laser-produced plasma expanding in vacuum field and in magnetized background revealed fundamental differences in structure and behavior of electric potential in plasma. In presence of frozen-in southward field direct {\guillemotleft}sub-solar{\guillemotright} penetration of outside electric potential deep inside of magnetosphere was observed taking place with velocity close to upstream Alfven speed.