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Figure B–2. Separation of ions through the magnetic sector
Thermo Fisher Scientific
For a fixed radius, the equation reduces to Equation 2:
For an electromagnet with a fixed accelerating voltage the equation
can be reduced to Equation 3:
This is the basic mass spectrometer equation used by Prima PRO
instrument.
If a fixed position ion detector is placed at the exit from the
electromagnet, the mass of the ion arriving at the detector can be
selected by varying the magnetic field. Refer to Figure B–2. The ion
signal measured at the detector is then proportional to the
concentration of the corresponding component in the sample gas.
This enables the mass spectrometer to be used as a compositional gas
analyser. The constant of proportionality is determined by calibration
against known gas standards.
Analysis and calibration may be complicated by overlapping mass
spectra as a result of the sample gas mixture. Methods to make such
overlaps less convoluted are discussed later.
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Technical Description: System
MV
constant
2
H
Equation 2.
2
M
H
Equation 3.
Principle of Operation
B-3
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