Method and inlet control system for controlling a gas flow sample to an evacuated chamber
US4018241A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 3, 1975 |
| Grant date | Apr 19, 1977 |
| Priority date | — |
| Expiry date | Oct 3, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/7761
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method and inlet control system for controlling a gas flow sample to an evacuated chamber such as found in a mass spectrometer, is disclosed. The system utilizes a short inlet passage having an effective opening determined by a tapered diamond or steel tip needle adjacent to the inlet passage. The needle is positionally adjusted with respect to the inlet passage by being mounted on a piezoelectric crystal which is flexed by coupling thereto an electric potential derived by sensing the ions at the ionization chamber of a mass spectrometer, for example, and developing therefrom an electric signal indicative of the total pressure within the ionization chamber. The signal coupled to the piezoelectric crystal is preferably a pulse-width modulated signal with the needle maintaining the inlet passage closed except during the time that the piezoelectric crystal is flexed due to a received pulse. A vacuum pump, and a quadrupole filter, both of which are relatively small, are also disclosed, so that a mass spectrometer system, for example, is sufficiently compact so as to be useful, in conjunction with a respiratory valve, for the analysis of respiratory gases. The method for controlling a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.