The helium vacuum-ultraviolet laser

Abstract

The emission spectrum of electron bombarded liquid helium has a broad continuum centered around 800 A, which is believed to originate in the A'E+u --> X'E+g transition in He2. This system has been studied as a possible medium for a vacuum-ultraviolet laser, It was found that dense helium gas would be better for such a laser. A transversely excited laser was built and tested on nitrogen and hydrogen before trying helium at ten atmospheres pressure. Lasing was observed with nitrogen, but it was never confirmed in the other two gases. Possible causes of failure are discussed along with several suggested improvements in the system. Finally, the feasibility of a pulsed-electron-accelerator powered laser is considered.