Megagauss Magnetic Field Generation and Plasma Jet Formation on Solid Targets Irradiated by an Ultraintense Picosecond Laser Pulse

The spatial and temporal evolution of spontaneous megagauss magnetic fields, generated during the interaction of a picosecond pulse with solid targets at irradiances above $5\times {10}^{18}\mathrm{W}/{\mathrm{cm}}^2$ have been measured using Faraday rotation with picosecond resolution. A high density plasma jet has been observed simultaneously with the magnetic fields by interferometry and optical emission. Two-dimensional magnetohydrodynamic simulations reproduced the main features of the experiment and showed that the jet formation is due to pinching by the magnetic fields.