Accession Number:

ADA282041

Title:

The Development of Laboratory Ion Sources for Mass Spectrometer Calibration

Descriptive Note:

Final rept. 2 May 1991-3 Aug 1993

Corporate Author:

BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING

Personal Author(s):

Report Date:

1993-08-01

Pagination or Media Count:

44.0

Abstract:

Electron impact ion sources were developed for the purpose of quadrupole mass spectrometer calibration in the laboratory. Prototype ion sources were constructed, and tested for operation in both positive and negative ion modes. In the positive mode, sensitivities approaching 10 exp-3 Atorr were obtained at the highest filament currents tested. Ion currents were linear over an order of magnitude in pressure. Collected ion currents generally increased with electron energy, following somewhat the trend with total ionization cross section. The results of energy analysis of the ion beams are consistent with Gaussian beams with relatively wide variances. Typical beam energies peaked in the regime of 30-35V, with variances of 17-18V. The ion beams did not appear to be fully accelerated at the analyzing electrode. The beams generally seemed to become more Gaussian with reduced variances at the lower electron energies. The use of magnets did not noticeably improve ion source performance in the positive ion mode. However, it did eliminate a significant background current problem at the collector plate. In the negative ion mode, total collected negative ion currents using SF6 were approximately two orders of magnitude less than under comparable conditions in the positive ion mode.

Subject Categories:

  • Inorganic Chemistry
  • Test Facilities, Equipment and Methods
  • Particle Accelerators
  • Nuclear Physics and Elementary Particle Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE