A high speed valve has a conductive flyer plate responsive to eddy currents induced by an adjacent coil. The eddy currents generate a repulsive force which opens the valve, and a low-mass flyer plate and spring combined with a resonant plate and spring combination provide a fast opening and closing time for the valve. A nozzle structure directs a supersonic flow of gas into a rectangular array of high-density gas suitable for interaction with a laser beam transverse to the rectangular array of jets for the production of wakefield interaction, leading to very high-energy electrons from the gas jet.