  A strong quasi-stationary magnetic field is generated in hollow targets with
curved internal surface under the action of a relativistically intense
picosecond laser pulse. Experimental data evidence formation of quasistationary
strongly magnetized plasma structures decaying on the hundred picoseconds time
scale, with the maximum value of magnetic field strength of the kilotesla
scale. Numerical simulations unravel the importance of transient processes
during the magnetic field generation, and suggest the existence of fast and
slow regimes of plasmoid evolution depending on the interaction parameters. The
principal setup is universal for perspective highly magnetized plasma
application and fundamental studies.
