A quasisteady model for the plasma ablated from a thick foil by a laser pulse, at low φaλ2L and R/λ2L within a low, narrow range, is given (φa is absorbed intensity, λL wavelength, R focal-spot radius). An approximate analytical solution is given for the two-dimensional plasma dynamics. At large magnetic Reynolds number RM, the morphology of the magnetic field shows features in agreement with recent results for high intensities. Current lines are open: electric current flows toward the spot near its axis, then turns and flows away. The efficiency of converting light energy into electric energy peaks at RM∼1. Both the validity of the model and accuracy of the solution are discussed. The neighborhood of the spot boundary is analyzed in detail by extending classical Prandtl–Meyer results.