Producing ultrashort, ultraintense plasma-based soft-x-ray laser pulses by high-harmonic seeding

Simulations show that intense plasma-amplified pulses of 100 fs duration and below are feasible by seeding specifically tailored plasma with an ultrashort pulse of high harmonic radiation. Seeding overcomes gain narrowing by driving amplifying media into saturation earlier, and compensates for reduced gain resulting from boosting the lasing transition linewidth. We conclude that ultrahigh intensities (above 10{sup 16} W cm{sup -2}) could be reached.