What is the principle of operation of the cyclotron?

In the cyclotron, heavy accelerated particles are injected into the chamber near its center. After that, they move inside the cavity of two slightly spaced half-cylinders (dees), placed in a vacuum chamber between the poles of a strong electromagnet. The uniform magnetic field of this electromagnet bends the trajectory of the particles. The acceleration of moving particles occurs at the moment when they find themselves in the gap between the dees. In this place, they are acted upon by an electric field created by an electric generator of high frequency, which coincides with the frequency of revolution of particles inside the cyclotron (cyclotron frequency). At not too high (nonrelativistic) velocities, this frequency does not depend on the energy of the particles, so that the particles always enter the gap between the dees at the same time instant. Each time they receive a certain speed increment, they continue their movement further along a circle of ever larger radius, and the trajectory of their movement forms a flat unwinding spiral. At the last turn of this spiral, an additional deflecting field is switched on, and the beam of accelerated particles is brought out. Since the magnetic field that sets the orbit of the beam is invariable, and the accelerating high-frequency electric field also does not change the parameters during the acceleration of particles, the cyclotron can operate in a continuous mode: all the turns of the spiral are filled with particles of the ion beam.