Study of laser produced plasma in a longitudinal magnetic field

Abstract

Laser produced plasma embedded in a longitudinal magnetic field was studied using a 1 MA pulsed power generator coupled with a 50 TW laser. Half turn coil loads with an internal diameter of 2.5-3.5 mm generate a 50-70 T axial magnetic field near the load. A subpicosecond laser pulse with an intensity of 1018-1019 W/cm2 irradiates a thin Si foil target in the magnetic field of the coil load. A laser produced plasma plume collimates within the longitudinal field to a narrow jet 0.2-0.3 mm in diameter with a length of 3-4 mm and an electron plasma density of (0.2-1) × 1020 cm-3 on the jet axis. The jet propagates with a velocity of 160-200 km/s in general agreement with magnetohydrodynamic simulations. X-ray spectral measurements show an increase in the plasma electron density resulting from the magnetic confinement of the jet.