Laser plasma simulations of the generation processes of Alfven and collisionless shock waves in space plasma

Generation of Alfven waves propagating along external magnetic field B₀ and Collisionless Shock Waves propagating across B₀ are studied in experiments with laser- produced plasma and magnetized background plasma. The collisionless interaction of interpenetrating plasma flows takes place through a so-called Magnetic Laminar Mechanism (MLM) or Larmor Coupling. At the edge of diamagnetic cavity LP-ions produce induction electric field E_φ which accelerates BP-ions while LP-ions rotate in opposite direction. The ions movement generates sheared azimuthal magnetic field B_φ which could launches torsional Alfven wave. In previous experiments at KI-1 large scale facility a generation of strong perturbations propagating across B₀ with magnetosonic speed has been studied at a moderate value of interaction parameter δ∼0.3. In the present work we report on experiments at conditions of 5∼R2 and large Alfven-Mach number M_A∼10 in which strong transverse perturbations traveling at a scale of ∼1 m in background plasma at a density of ∼3*10¹³ cm^-3 is observed. At the same conditions but smaller M_A ∼ 2 a generation, the structure and dynamic of Alfven wave with wavelength ∼0.5 m propagating along fields B₀∼100÷500 G for a distance of ∼2.5 m is studied. (paper)