A simple photopreionization‐stabilized waveguide laser is energized effectively by fast Blumlein‐type pulsers and operates at pressures of up to 13 atm. The laser has an active plasma volume of ∼0.2 cm3and provides 20 ns gain‐switched pulses with beam energies of 10 mJ. The maximum pressures and beam energies are more than an order of magnitude higher than those published previously; the peak power is enhanced by two orders of magnitude.