MICROMETER-SIZED NOZZLES AND SKIMMERS FOR THE PRODUCTION OF SUPERSONIC HE ATOM BEAMS

Micrometer-sized nozzles and skimmers made from drawn glass tubes are described and tested for the production of highly monoenergetic He ato m beams. Glass nozzles with diameters between 1 mu m and 4 mu m when o perated at He source stagnation pressures of up to 1000 atm provide in tense beams with measured speed ratios of S = 50-100, in good agreemen t with the predicted behavior scaled from nozzles with larger openings . Miniature glass skimmers with diameters as small as 3 mu m were also successfully tested with conventional 10 mu m diameter nozzles. These miniature nozzle-beam sources can be used to greatly reduce the size of present-day He-atom surface-scattering time-of-flight spectrometers and to reduce the number of vacuum stages and the size of vacuum pump s. They also open up new experimental possibilities as illustrated by measurements of the spatial profiles of seeded nozzle beams. (C) 1997 American Institute of Physics.