Beam Control

The principle of the Lorentz force is used in applications such as beam control, spectrometers and electron microscopes.

In a spectrometer, the magnet is used to discriminate the energy and ionization state of charged particles. In a mass spectrometer, ionized particles of the material is accelerated and shot through a magnetic field.  Lorentz forces acting on the particles will bend their paths in proportion to the field strength, and the particles mass, velocity and charge sate.  This force is

F=qB X v = ma

where B is the magnetic field vector, v is the velocity vector.  The vector cross product B X v ensures force F acting on the particle and the resulting acceleration a are in a direction perpendicular to the direction of  the magnetic field and the velocity. 

For a given particle, stronger and more uniform field results in greater and more predictable deflection from the original path.  By using a moving particle detector and an array of detectors at the focal plane, the constituent particles, and by extension elements of the material can be quantified and analyzed.

A simple electron beam-focusing magnet - such as would be used in electron microscopes - would consist of a tube shaped magnet magnetized along its length. A beam of electrons shot through such a tube would be focused by the Lorentz force experienced by the electrons in the magnetic field of the magnet.  Permanent magnets used in these applications can result in substantial power savings.

Tailored magnetic field are also used in plasma chambers to keep particles from getting lost to the chamber walls.  Similarly, a field normal to the direction of particle travel, with adequate intensity, will shield that region from the charged particles by deflecting them.

For further inquiries, please e-mail us at info@dextermag.com -or- call us at:  800-345-4082 (In North America) or +44 (0) 1189 602430 (In Europe).