Britannica Sources used in this answer

How did radar technology help lead to the development of modern linear accelerators?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

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.

The development of modern linear accelerators was significantly advanced by the emergence of powerful radio-frequency (RF) technology created for radar during World War II.12

Before this period, linear machines for accelerating lighter particles like protons and electrons were limited by the lack of sufficiently powerful RF oscillators. The wartime research into radar led to the development of microwave technology, most notably the klystron amplifier and the magnetron. These devices provided the high-power RF sources necessary to generate the intense electromagnetic fields required for modern linear accelerators.1345

Specifically, William W. Hansen, a pioneer in microwave technology, applied his work on resonant cavities—which were essential to radar—to the design of electron accelerators. By 1947, he successfully constructed the first traveling-wave linear accelerator for electrons, utilizing the microwave technology refined during the war. Today, large-scale electron linacs continue to rely on these high-power klystrons to produce the electromagnetic fields that accelerate particles to high energies.324