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The National MagLab is funded by the National Science Foundation and the State of Florida.

Mass Spectrometer (Dual Sector)

Mass spectrometers are instruments that give scientists insight into the composition of complex materials. These spectrometers can analyze materials and identify atoms and molecules by examining how they react to magnetic fields.

The simpler single sector mass spectrometer is made with a single magnetic analyzer. This tutorial explores a widely used variation of this technology, namely, the double sector mass spectrometer. It has two analyzers – one magnetic, one electrostatic.

The interactive tutorial below gives you a look inside of a dual sector mass spectrometer.


  1. Observe the ions traveling through the Mass Spectrometer. The blue ions are the lightest, the green are heavier, and the red are heaviest.
  2. Turn on the machine’s magnetic field and set it to the lowest field strength. Watch what happens to the heaviest ions when they hit the curve in the tunnel through the magnetic field. Watch the other ions make it all the way to the detector.
  3. Adjust the strength of the electric field and observe the effects lowering and raising the strength of the field has on the ions.
  4. Try different combinations of magnetic field and electric field strength and overserve what changes.
  5. Monitor the ion counter to see what impacts your changes have.

The ions enter the first (magnetic) analyzer, where they interact with the magnetic field and are sorted by mass-to-charge ratio. The ions that make it through that curve proceed into the second (electrostatic) analyzer. The ions are traveling at different speeds, and without the help of the electrostatic field, most would crash before making it to the Detector. The charge of ion reacts to the charged walls of the chamber. If the ions are repelled from the walls enough to make it through the chamber, they get counted.