Mass analyzer system with reduced drift
US4746794A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 20, 1986 |
| Grant date | May 24, 1988 |
| Priority date | — |
| Expiry date | Oct 20, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J49/04
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A mass analyzer in which an ion signal, typically from a plasma, travels through an orifice into a vacuum chamber, and through a focussing system in the vacuum chamber into a mass spectrometer and ion detector. Drift of the detected ion signal, and differences in drift of the detected ion signal for different elements, are greatly reduced by a small shadow stop placed in the vacuum chamber immediately behind the orifice. The shadow stop and plate containing the orifice are both preferably grounded. The focussing system includes a Bessel box lens, and drift is further reduced by insulating the stop in the Bessel box lens from the barrel and biasing the Bessel stop differently from the barrel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.