Leo Szilard (1898 - 1964)

In his Berlin and London days between the world wars, Leo Szilard thought about household refrigerators and nuclear chain reactions. He also invented many of the central features of the accelerators that would take the study of nuclear and particle physics to high energies.
It is little appreciated, even in William Lanouette's excellent biography, that Leo Szilard worked as a professional inventor during most of his scientific career, constantly filing patent applications that covered an astonishingly large range of novel ideas.

Born in Budapest in 1898, Szilard came to Berlin to study engineering after World War I and the upheavals in Hungary that followed in its wake. During his Berlin period (1920–1933) Szilard was granted 31 patents and abandoned 5 other patent applications. Contrast this with his published output as a physicist during the same period: two theoretical papers and two experimental articles.

Hardly any of his inventions seem to have been realized in practice, and there is no evidence that he reaped any financial rewards from his German patents or their foreign equivalents. One exception is a patent on a "Discharge Tube to Be Used as an Electron Source," which he assigned to the Siemens–Schuckert Company in Berlin. One may speculate that he acted as a paid consultant to that firm.

The most famous of Szilard's patents is, of course, his 1934 patent for the idea of a nuclear chain reaction. He was, by then, an unemployed refugee in London. Though the patent did mention uranium and thorium in passing, Szilard had his eye primarily on beryllium. The following year, to keep this patent secret, he assigned it to the British Admiralty.

During Szilard's Berlin period, however, a more mundane topic had been at the center of his technical interests: refrigerators, presumably for household use. The commercially available refrigerators at the time were noisy and generally unreliable. Szilard tried to propose devices without moving parts. These were covered by 16 patents, of which 5 were filed jointly with Albert Einstein.

Szilard's collaboration with this illustrious former patent clerk was not confined to refrigerators. It extended to the fairly well-known Einstein­Szilard pump for liquid metals, for which they filed a British patent in 1927. The proposed pump also had no moving parts. The key idea of the invention was to use a varying magnetic field to induce a ponderomotive force on a closed current loop in the fluid conductor. Nowadays pumps of this kind are used to circulate liquid sodium coolant in nuclear reactors.