Observation of plasma confinement in picosecond laser-plasma interactions

Novel features associated with multiterawatt laser interactions with solid targets at incident irradiances in the range (1.0--12.0)×{}10¹⁷ W cm^-2 are presented. Collimation of the plasma flow normal to the target surface has been observed in time-integrated x-ray images and ion-velocity measurements. Ions emitted from the target have a characteristic energy of typically 100 keV. The ion spectrum extends to 1.5 MeV. Calculations are presented that suggest the observed collimation is due to a large magnetic field pinching the plasma.