Betatron

A betatron is a type of cyclic particle accelerator for electrons. It consists of a torus-shaped vacuum chamber with an electron source. Circling the torus is an iron transformer core with a wire winding around it. The device functions similarly to a transformer, with the electrons in the torus-shaped vacuum chamber as its secondary coil. An alternating current in the primary coils accelerates electrons in the vacuum around a circular path. The betatron was the first machine capable of producing electron beams at energies higher than could be achieved with a simple electron gun, and the first circular accelerator in which particles orbited at a constant radius.^[1]

The concept of the betatron had been proposed as early as 1922 by Joseph Slepian.^[2] Through the 1920s and 30s a number of theoretical problems related to the device were considered by scientists including Rolf Wideroe,^[3][4] Ernest Walton, and Max Steenbeck.^[5] The first working betatron was constructed by Donald Kerst at the University of Illinois Urbana-Champaign in 1940.^[6][7][8]