Editing Mark Oliphant (section)

=== Radar ===
[[File:Original cavity magnetron, 1940 (9663811280).jpg|thumb| [[Anode]] of the original cavity magnetron developed by [[John Randall (physicist)|John Randall]] and [[Harry Boot]] at Birmingham University]]
In 1938, Oliphant became involved with the development of [[radar]], then still a secret. While visiting prototype radar stations, he realised that shorter-wavelength [[radio waves]] were needed urgently, especially if there was to be any chance of building a radar set small enough to fit into an aircraft. In August 1939, he took a small group to [[Ventnor]], on the [[Isle of Wight]], to examine the [[Chain Home]] system first hand. He obtained a grant from the [[British Admiralty|Admiralty]] to develop radar systems with wavelengths less than {{convert|10|cm|0}}; the best available at the time was {{convert|150|cm|-1}}.<ref name="odnb" />

Oliphant's group at Birmingham worked on developing two promising devices, the [[klystron]] and the [[magnetron]]. Working with [[James Sayers (physicist)|James Sayers]], Oliphant managed to produce an improved version of the klystron capable of generating 400W. Meanwhile, two more members of his Birmingham team, [[John Randall (physicist)|John Randall]] and [[Harry Boot]], worked on a radical new design, a cavity magnetron. By February 1940, they had an output of 400W with a wavelength of {{convert|9.8|cm}}, just the kind of [[microwaves|short wavelengths]] needed for good airborne radars. The magnetron's power was soon increased a hundred-fold, and Birmingham concentrated on magnetron development. The first operational magnetrons were delivered in August 1941. This invention was one of the key scientific breakthroughs during the war and played a major part in defeating the German [[U-boats]], intercepting enemy bombers, and in directing Allied bombers.{{sfn|Cockburn|Ellyard|1981|pp=83–90}}

In 1940, the [[Fall of France]], and the possibility that Britain might be invaded, prompted Oliphant to send his wife and children to Australia. The [[Fall of Singapore]] in February 1942 led him to offer his services to [[John Madsen (physicist)|John Madsen]], the Professor of Electrical Engineering at the [[University of Sydney]], and the head of the Radiophysics Laboratory at the [[CSIRO|Council for Scientific and Industrial Research]], which was responsible for developing radar.{{sfn|Cockburn|Ellyard|1981|pp=83–90}}{{sfn|Mellor|1958|pp=427–428}} He embarked from Glasgow for Australia on {{ship|QSMV|Dominion Monarch}} on 20 March. The voyage, part of a 46-ship convoy, was a slow one, with the convoy frequently zigzagging to avoid U-boats, and the ship did not reach Fremantle until 27 May.{{sfn|Cockburn|Ellyard|1981|pp=91–92}}

The Australians were already preparing to produce radar sets locally. Oliphant persuaded Professor [[Thomas Laby]] to release [[Eric Burhop]] and [[Leslie H. Martin|Leslie Martin]] from their work on optical munitions to work on radar, and they succeeded in building a cavity magnetron in their laboratory at the [[University of Melbourne]] in May 1942.{{sfn|Mellor|1958|p=446}} Oliphant worked with Martin on the process of moving the magnetrons for the laboratory to the production line.{{sfn|Cockburn|Ellyard|1981|pp=92–93}} Over 2,000 radar sets were produced in Australia during the war.{{sfn|Mellor|1958|p=450}}