Device used to produce beams of energetic charged particles (see Elementary Particles) and to direct them against various targets for studies of the structure and
components of the atomic nucleus (see Atom) and of the Forces holding it together. Accelerators also have applications in medicine and
industry, most notably in the production of radioisotopes. The first stage of any
accelerator is an Ion source to produce the Charged particles from a neutral Gas (see States Of Matter). The charged particles are accelerated by Electric Fields. In linear accelerators, which are the most powerful and efficient Electron accelerators, the particle path is a straight line. The early linear
accelerators used large static electric charges, which produced an electric Field along the length of an evacuated tube to accelerate the particles. Present
linear accelerators use Electromagnetic Waves to accomplish the acceleration. To reach high energies without prohibitively
long paths, E.O. Lawrence designed the cyclotron, in which a cylindrical
magnet bends the particle beam into a circular path in a hollow circular Metal box that is split in half to form two D-shaped sections. A Radio Frequency Electric Field is applied across the gap, accelerating the particle each Time it crosses the gap. In the synchrocyclotron, used to accelerate Proton, the Frequency of the accelerating electric field steadily decreases to match the decreasing
angular velocity of the proton caused by the increase of its Mass at relativistic velocities, i.e., those close to the Speed of Light. In the synchrotron, a ring of magnets (see Magnetism) surrounding a doughnut-shaped Vacuum tank produces a Magnetic Field that rises in step with the proton velocities, thus keeping the radius of
their paths constant; this design eliminates the need for a center section of the
magnet, allowing construction of rings with diameters measured in miles. The
Superconducting (see Superconductivity) Supercollider (SSC), which began construction in 1989, was to be the world's
largest proton accelerator, encircling Waxahachie, Tex. (30 mi/48 km south of
Dallas), with its 54 -mi (87 -km) oval main ring. The U.S. Congress killed the
project in 1993. A smaller proton collider is under construction at Cern,
outside Geneva, Switzerland.