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Address
196084, St.-Petersburg
Parkovaya str. 4
| ICQ:
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| т/ф: (812) | 388-3814 388-7924 388-3433 |
Quadrupole mass-spectrometer.
Basic characteristics
| Parameters | Values |
| Resolution | 200 |
| Measured masses range | 1-200 |
| Weight | 2.4 kg |
| Time required for analysis | 0.02-60 c/a.e.m |
| Argon sensitivity | 6*10-4 A/mbar |
| Max working pressure | 1*10-4 mbar |
| Min measured concentration | 2*10-12 mbar |
| Analyzer operating temperature | 1500C |
| Analyzer temperature at a heating unit mode | 3000C |
| Electronics operating temperature | 0-400C |
The quadrupole mass-spectrometer possesses high speed of measurement, the maximal stability, has high resolution, and great dynamic range. The software is expressed by means of digital or analog transferring channels, and also by Ethernet. Simple interface, an opportunity of integration with existing data bases, and the creation of library of the given spectra is also presented. The compact size and modular execution allows to adapt the system to solving specific gas analytical problems. Measurements by sliding average values, automatic measurement range search and peak location with step equal to 1 а.е.м. simplify and improve the data processing. Quadrupole mass-spectrometer is suitable for problems of analyzing the structure of residual gases in the vacuum unit.
Principle of operation of quadrupole mass-spectrometer.
The basic scheme of the analyzer (without the body):
- Source of ions. The generation of ions is created by colliding with electrons.
- Rods. The ions become separated by their mass number.
- Collector
- Ionizer
- Heater cathode
- membrane
The given gas is ionized by the beam of electrons, emitted by the heater cathode (Filament), reaching the collector. Ions get to the analyzer through the membrane. The analyzer is a high frequency electric quadrupole and consists of four precisely straight and parallel rods so arranged that the beam of ions from the ionization source of the spectrometer is directed axially between them. A voltage comprising a DC component and a radio frequency component is applied between adjacent rods, opposite rods being electrically connected. Once inside the quadrupole the ions will oscillate in the (x) (y) direction as a result of the high frequency electric field. The oscillations depends on the voltage and the ionic mass number.
Trajectories of ions can be both stable and unstable. Ions with stable trajectories (the amplitude of their oscillation is less than distance from the central quadrupole axis up to a core) pass through the analyzer and get on a collector, creating current in a circuit of a collector, which force is proportional to the partial pressure. While moving ions with unstable trajectories along the analyzer their amplitude increases. Colliding with electrodes ions are neutralized. For receiving spectrum the pressure on electrodes of the ionizer is should be changed.
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