A PRACTICAL SELF-HEALING MERCURY TARGET FOR EFFICIENT GENERATION OF SOFT-X-RAY RADIATION

We have developed a self-healing mercury-wetted target as a practical source of soft x-ray radiation for photoexciting extreme ultraviolet l asers. A threaded rod, rotating in a pool of mercury, demonstrates a s oft x-ray conversion efficiency similar to that of expendable gold-coa ted targets in synchronous photopumping of a photoionization Xe2+ lase r at 109 nm. Surfaces self-heal or are continuously regenerated by rew etting, while mercury debris is removed by evaporation from the target chamber walls and optics. Long target lifetime and self-cleaning perf ormance of the new target system are attractive features in future hig h-repetition-rate, high-throughput applications for photopumping of ex treme ultraviolet or soft x-ray lasers, and more generally as incohere nt sources for soft x-ray lithography and spectroscopy.