Gridded electron reversal ionizer
US5256874A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 25, 1992 |
| Grant date | Oct 26, 1993 |
| Priority date | — |
| Expiry date | Mar 25, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J49/147
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.