A linear accelerator is a special linear device used to accelerate atomic and sub-atomic particles to extremely high velocities. These accelerators use electric and magnetic fields to accelerate, steer, and focus the particles to a fine degree of precision. This is done by first placing a proton in a tube with negative potential. The tubes" electric fields from there on are reversed by using alternating current throughout the various tubes. Tubes of increasing size are used to accelerate the particles, while the time spent in each tube is the same. The particles are then shot directly into the end of the tube, usually onto a piece of film and an x-ray plate. These linear accelerators can only be used on ions, atomic nuclei, protons and/or electrons. They cannot act on uncharged particles such as neutral atoms or neutrons. .
To accelerate particles to MeV (mega-electron-volt) or GeV (giga-electron-volts) a radio frequency linear accelerator (RF linac) is used. In these RF linacs, the electric and magnetic frequencies oscillate at extremely high frequencies, known as "radio frequencies," in the range of millions to billions of cycles per second. These RF linacs are the best ways to accelerate particles to MeV and GeV energies.
The particles in these energy ranges have extremely useful applications in the scientific, industrial, medical and military fields. The medical applications are the most important. There are the abilities to produce radioisotopes for medical applications, radiation effects for cancer therapy, and thermal and energetic neutron beams for other various medical applications. There is the ability to use the particle accelerator for material inspection and explosive detection in the military and industrial fields. In the scientific field of research there is the ability to study special types of light and electromagnetic radiation for solid-state physics applications and energetic particle beams for elementary particle physics research.
