What historical developments were required prior to the invention of the particle accelerator, and which scientists made these contributions?

The particle accelerator uses electromagnetic fields to propel charged particles, contained in beams, to very high speeds. The electrodynamic accelerator was first developed in the 1920s. As early as the 1910s, however, physicist Ernest Rutherford of New Zealand had experiment with shooting alpha particles into nitrogen. The electrodynamic accelerator propels particles through changing electromagnetic fields, through which the particles may pass multiple times, which supports increased output energy. The development of this class was an important step toward the large-scale accelerator. Most important developments occurred in the 1930s, in part through the Allies versus Axis race to develop nuclear weapons.
Among the important contributors toward the particle accelerator were Leó Szilárd, born in Hungary, and Enrico Fermi, born in Italy. Leo Szilárd conceived the nuclear chain reaction in 1933. Fermi’s work on slow neutrons won him the Nobel Prize for Physics in 1938. Szilárd and Fermi together patented the idea of the nuclear reactor in 1934. Inspired by the work of Norway’s Rolf Widerøe, Ernest Lawrence of the United States went on to develop the cyclotron and later won the 1939 Nobel Prize. Max Steenbeck of Germany patented a betatron electron accelerator in 1934. This work was advanced in the United States by Donald Kerst, while after the Second World War, Steenbeck contributed substantially to the Soviet nuclear program.
https://web.archive.org/web/20060220135256/http://www.aip.org/history/lawrence/

https://www.aps.org/publications/apsnews/201112/physicshistory.cfm