Quadrupol Mass Spectrometer

Quadrupole Mass SpectrometerWe offer Quadrupole Mass Spectrometers from AMETEK®, a leading American manufacturer of process analytics. The product portfolio consists of single, standalone instruments as well as complete systems for qualitative and quantitative gas analysis. The mass range of the devices spans from 1 to 300 amu. Instruments from the DYCOR® series can be configured for various applications. Mass spectrometer systems with a differential pumping stage provide a separate operating volume, where the gas composition can be traced. This is connected to the process environment by an appropriate gas inlet system. These setups are, in addition, suitable for gas analysis up to 1.3 bar. With the ProLine Process Mass Spectrometer, we are able to offer optimal
process analysis and control tool for very demanding applications.

Functional principle Quadrupole Mass SpectrometersPrinciple of operation
Quadrupole Mass Spectrometer consist of four parts: ion source, mass filter, detector and control unit. In the ion source gas particles are ionized by electron bombardment and form ions. The critical parameters of the created ion beam and the preferred type of ionization are dependent on the application. A major issue, especially when a low number of particles must be detected and differentiated from the background, is the influence of the ionization system on the investigated process. After ionization, ions continue through an electrostatic focus plate system and are directed from the ion source into the mass filter.

The mass filter separates the ions in an oscillating electric field, which is created in the space within 4 parallel rods. Such an electric field is termed quadrupolar, as it originates from four "poles". The field has a DC component as well, which allows to tune the device to a "constant resolution" or "constant sensitivity" mode. All these voltages are specified in a way so that only ions with a certain mass-to-charge ratio can pass the mass filter at a time. All other ions are deflected from their path by electrical fields, neutralised and thus, not detected. A vacuum of about 10-4 mbar or better is needed for the ions to be able to pass the analyzer. Otherwise the mean free path of the particles is too short for particles to reach the detector at the end of the quadrupole.
The ions (ion currents) that pass the mass filter are collected by the detector. Faraday cup or SEV detectors are commonly used. The current pulses are subsequently amplified and processed by the control unit.
The control unit supplies the voltage for the ion source, the quadrupole system and the detector. In addition, it receives the detector signal, amplifies and  processes  it. A connected computer controls the measurements and  displays the results graphically in the dedicated software program.

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