Mass Spectrometer

The mass spectrometer is an instrument which can measure the masses and relative concentrations of atoms and molecules. It makes use of the basic magnetic force on a moving charged particle.

Derive radius expressionHow does a velocity selector work?
Magnetic interactions with chargeApplications of mass spectrometers
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Electromagnetic force

Magnetic field concepts
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Circular Path from Magnetic Field

If a charge moves into a magnetic field with direction perpendicular to the field, it will follow a circular path. The magnetic force, being perpendicular to the velocity, provides the centripetal force.

Application in mass spectrometerApplication in cyclotron
Magnetic confinement
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Magnetic force

Magnetic field concepts
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Velocity Selector

A velocity selector is used with mass spectrometers to select only charged particles with a specific velocity for analysis. It makes use of a geometry where opposing electric and magnetic forces match for a specific particle speed. It therefore lets through undeflected only those particles with the selected velocity.

Application in mass spectrometer
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Magnetic field concepts
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Applications of Mass Spectrometers

Mass spectrometers are sensitive detectors of isotopes based on their masses. They are used in carbon dating and other radioactive dating processes. The combination of a mass spectrometer and a gas chromatograph makes a powerful tool for the detection of trace quantities of contaminants or toxins. A number of satellites and spacecraft have mass spectrometers for the identification of the small numbers of particles intercepted in space. For example, the SOHO satellite uses a mass spectrometer to analyze the solar wind.

Mass spectrometers are used for the analysis of residual gases in high vacuum systems.

Display from residual gas analyzer
Isotopic abundances of krypton
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Magnetic field concepts
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Magnetohydrodynamics

A magnetohydrodynamic generator has been described as a magnet on the tail of a jet engine. A super-hot plasma is created, ionizing the atomsof the fuel mixture. The magnetic field deflects positive and negative charges in differentdirections. Collectingplates for the chargesprovide a DC voltage.

Magnetohydrodynamics as an electricity generation process holds the possibility of very efficient fuel utilization because the extremely high temperatures at which it operates correlate to a high Carnot efficiency.Its practical application has been slow in coming because of a number of problems.

Magnetic interactions with charge
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Magnetic field concepts
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