High Intensity Molecular Beam Apparatus

Abstract

A high intensity molecular beam apparatus is described which is based on a supersonic stream gas source. Intensities of the order of 10 17 molecules/cm 2 /sec have been achieved with nitrogen. The effects on performance of Mach number, source pressure, and geometry are summarized. Results are compared with theory.

Continuum-source molecular beams

“…Using a as a curve-fitting parameter to match the prediction of Eq. (17) with the data of Deckers and Fenn 28 at the intensity maximum, Valleau and Deckers obtain a reasonable agreement between the experimental and theoretical curves. Thus the situation at present is that two explanations are available to explain the intensity curve shape in the interesting region near the maximum, with experimental evidence available which supports the idea of a shock disturbance external to the skimmer and quantitative analysis available which clearly shows that collisions after skimbinary jets have been shown to have the calculated velocity but in addition can be much enriched in the heavier component.…”

Historical Account And Branching To Rarefied Gas Dynamics Of Atomic and Molecular Beams : A Continuing And Fascinating Odyssey Commemorated By Nobel Prizes Awarded To 23 Laureates In Physics And Chemistry

“…This solution has been widely used after the construction by J. B. Fenn** et al [3,6,7] in 1963 in Princeton, of a first supersonic molecular beam source operated by 32 inch-diffusion pumps.…”

John Bennett Fenn: A Curious Road to the Prize

“…Vacuum pumps with high pumping speed would be needed to handle the mass flow rate of the carrier gas; very high pumping speed; on the order of tens of thousands liters per second! The molecular beam apparatus described in the Review of Scientific Instruments in 1963 [10], Fenn's first publication after a 5-year hiatus, had two 32-inch diffusion pumps, one in the nozzle source chamber, and one in the skimmercollimator chamber, to avoid scattering losses.…”