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How does a cyclotron accelerate charged particles?

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Diagram of a linear proton resonance accelerator, or linac, showing protons entering from a source, passing through a series of labeled drift tubes powered by a radio-frequency source, and exiting as a beam through a cavity. — particle accelerator The accelerator is a large-diameter tube within which an electric field oscillates at a high radio frequency. Within the accelerator tube are smaller diameter metallic drift tubes, which are carefully sized and spaced to shield the protons from decelerating oscillations of the electric field. In the spaces between the drift tubes, the electric field is oriented properly to accelerate the protons in their direction of travel.

A cyclotron accelerates charged particles using a combination of a constant magnetic field and an alternating electric field.12

The device consists of two hollow, D-shaped electrodes known as dees, placed within an evacuated chamber between the poles of a large magnet. Particles are introduced at the center of the gap between these dees.12

The acceleration process functions as follows:
* Electric Field: A radio-frequency oscillator creates an alternating voltage across the gap between the dees. As particles cross this gap, the electric field propels them, increasing their speed and energy.12
* Magnetic Field: Inside the hollow dees, there is no electric field. Instead, the uniform magnetic field forces the particles into a semicircular path.12
* Spiral Path: Because the electric field reverses polarity at a fixed frequency, the particles are accelerated every time they cross the gap. As their speed increases, the radius of their orbit grows, resulting in a spiral-like trajectory.12

This process continues until the particles reach high energies, though it is eventually limited by relativistic mass increases as the particles approach the speed of light.12