AC-modulation quadrupole mass spectrometer
US4695724A · kind A · utility
6Cited by
3References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 24, 1986 |
| Grant date | Sep 22, 1987 |
| Priority date | — |
| Expiry date | Nov 24, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J49/0013
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A quadrupole mass spectrometer generates a stream of ionized particles which are modulated by an AC voltage and transmitted through a quadrupole analyzer to a detection unit. The detection unit detects at a collector electrode thereof a modulated ion current which is fed to a phase detector. The phase detector synchronizes the modulated ion current with a signal of known frequency to produce a DC voltage representative of the level of the modulated ion current. By modulating the ionized particles with the AC voltage, the S/N ratio is improved and adverse effects of external noise are diminished.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.