APPLICATION OF DROPLET EVAPORATION MODEL TO THE EXPANSION COOLING OF AN ATOMIC URANIUM BEAM

By using the technique of laser induced fluorescence to measure the ve locity distribution function of an atomic uranium beam produced by eva poration from a spherical surface by electron bombardment, we have obs erved the phenomenon of vapour expansion cooling. Agreement between th e theoretical analysis and experimental results is satisfactory. Some of the results are compared with those published by Havazelet and Birn boim and good agreement is achieved.