Production of VUV coherent light by harmonic generation with the optical klystron of super-ACO

The aim of the experiment presented was to develop a usable source of coherent light in the vacuum ultraviolet (VUV) range (200-50 nm) using the Super-ACO storage ring. A presentation is made of the most recent results where coherent photons have been produced at the 3rd (177 nm) and 5th (106 nm) harmonics of the incident laser. The better performance of the new machine and the laser, compared to the older ACO, is largely offset by experimental difficulties. The number of photons is, however. larger than that obtained with the ACO, but it is approximately one order of magnitude below the expected rate. This seems to be due to positron beam instabilities. The authors believe that the extremely critical alignment of the whole experiment, from the injection laser to the monochromator, does not appear to be compatible with a user facility.