betatron

A particle accelerator in which electrons are held in a circular orbit by a magnetic field, and accelerated by a varying electric field superimposed. Very high particle energies have been attained. It is used for research on high-energy electron behaviour or to produce high-energy X-rays.

A betatron is a particle accelerator developed by Donald Kerst at the University of Illinois in 1940 to accelerate electrons. The name "betatron" (a reference to the beta particle, a fast electron) was chosen during a departmental contest.

The stable orbit for the electrons satisfies where θ0 is the flux with the orbit at r0 is the radius and H0 is the magnetic field at r0.

Betatrons were historically employed in particle physics experiments to provide high energy beams of electrons—up to about 300 MeV. If the electron beam is directed at a metal plate, the betatron can be used as a source of energetic x-rays or gamma rays;

Because the mass of the electron increases at relativistic speeds, the cyclotron becomes less efficient at higher energies, placing an upper limit on its beam energy.

The Radiation Center, the first private medical center to treat cancer patients with a betatron was opened by Dr. O.