ELECTRON IMPACT IONIZATION CROSS SECTIONS.
Abstract
A program has been undertaken to measure absolute electron-ionization cross sections for metals and other materials of low vapor pressure. Equipment necessary to make these measurements, ionizers, Knudsen cells, charged particle traps, and a large quadrupole mass spectrometer along with an electron-muliplier-particle detector, were designed and constructed. Many calibration tests were made. Absolute cross sections were measured as a function of electron energy for the formation of Ag(+), Ag(++), Cu(+) and Cu(++), from their respective neutral species. Neutral beam intensity was calibrated by use of a beam-trap weight-gain method, which seems less sensitive to systematic errors than the more common Knudsen cell weight loss method. Work continued on the development of the multiple-crossed-beam technique for measuring absolute cross sections, but no useful cross section data has yet been obtained in this way. During the course of the work several new ion source construction techniques were developed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1967
- Accession Number
- AD0826983
Entities
People
- Charles K. Crawford
Organizations
- Massachusetts Institute of Technology