A high-intensity beam of metastable helium atoms with good velocity resolution
- 1 January 1977
- journal article
- Published by IOP Publishing in Journal of Physics E: Scientific Instruments
- Vol. 10 (1), 90-94
- https://doi.org/10.1088/0022-3735/10/1/021
Abstract
The excitation of a low-energy ground state helium beam to its metastable states by electron impact is analysed. It is shown that the narrowest velocity distribution for the resulting metastable helium beam is obtained by directing the helium and electron beams parallel or antiparallel. A source of metastable helium atoms was constructed according to this analysis which produced a beam of 3*1014 metastable atoms/s sr with a velocity resolution of 3% FWHM for a room-temperature beam (E=66 meV). A possible source of errors in time-of-flight experiments with metastable atoms is pointed out.Keywords
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