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How did Cockcroft and Walton use a voltage multiplier to split lithium nuclei?

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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.

In 1932, John Cockcroft and Ernest Walton achieved the first nuclear reaction using artificially accelerated particles by utilizing a four-stage voltage multiplier, now known as the Cockcroft-Walton generator.12

To generate the necessary high voltage, they combined four rectifier-type direct-voltage power supplies in series using large rectifiers and high-voltage capacitors. An alternating voltage from a transformer was transmitted through an array of capacitors to reach higher stages, while a second group of capacitors maintained a constant direct voltage.1

Although power loss from corona discharge prevented them from reaching the theoretical maximum, the apparatus successfully accelerated protons to energies of 710 keV. By bombarding lithium nuclei with these protons, they caused each lithium nucleus to split into two helium nuclei, a landmark achievement in transmutation that earned them the 1951 Nobel Prize for Physics.123