Lawrence Berkeley National Laboratory

The particle-in-cell method is used to calculate the flow fields of gases formed by supersonic nozzles of different shapes under flow conditions typical of gasdynamic sources of molecular beams. The proposed calculation scheme is tested by comparing the calculated flow fields from an acoustic nozzle with the semiempirical calculations made by Ashkenas and Sherman. For a nozzle with a conical supersonic section the calculations are compared with the results of time-of-flight measurements made using the molecular beam generator at the St. Petersburg Institute of Nuclear Physics of the Russian Academy of Sciences. Prospects for the further use of these calculation methods to develop and optimize gasdynamic sources of molecular beams are discussed. © 1998 American Institute of Physics.