Reversal electron attachment ionizer for detection of trace species

US4933551A · kind A · utility

Assignee

• The United State of America as represented by the Administrator of the National Aeronautics Space Administration · US

Inventors

• Mark T. Bernius · Midland, US
• Ara Chutjian · La Cañada Flintridge, US

Key dates

• Filing date: Jun 5, 1989
• Grant date: Jun 12, 1990
• Expiry date: Jun 5, 2009

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J49/06
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An in-line reversal electron, high-current ionizer capable of focusing a beam of electrons to a reversal region and executing a reversal of said electrons, such that the electrons possess zero kinetic energy at the point of reversal, may be used to produce both negative and positive ions. A sample gas is introduced at the point of electron reversal for low energy electron-(sample gas) molecule attachment with high efficiency. The attachment process produces negative ions from the sample gas, which includes species present in trace (minute) amounts. These ions are extracted efficiently and directed to a mass analyzer where they may be detected and identified. The generation and detection of positive ions is accomplished in a similar fashion with minimal adjustment to potentials applied to the apparatus.