From radar to nuclear magnetic resonance

Abstract

As war engulfed Europe from September 1939, and the Axis powers overran most of the western European countries in 1940, the United States undertook to build up quickly its military capabilities. By late 1940, a full year before the U.S. was drawn into war as a combatant, there began a massive move of scientists, especially physicists, temporarily into new organizations set up to develop technologically advanced weapons. One of the first of these, destined to become one of the largest, was the “Radiation Laboratory,” so named with an intent to obscure its purpose, at the Massachusetts Institute of Technology, established in November of 1940 by the National Defense Research Committee (NDRC). Its mission was to develop radio detection and ranging (to become known as Radar), inspired by the startling performance of the pulsed cavity magnetron revealed to U.S. military officers and members of the National Defense Research Committee by the British “Tizard Mission.” Although magnetrons as generators of electromagnetic energy of short wavelength had been developed in several places many years earlier, the new magnetron was a breakthrough in that it could produce microwave pulses many orders of magnitude more intense than could anything else then in existence. It was an ideal device for the development of radar. The visit from the beleaguered British scientists and high military officers, headed by Sir Henry Tizard, had entered into this exchange of secret new military technology to try to obtain technical help and manufacturing support from US industry, relatively insulated from air attack. The cavity magnetron has been described, in view of its developed use in the war, as possibly the most important cargo ever to cross the Atlantic, although many other secret developments were included in the exchange. For example, the British progress toward releasing nuclear energy was also revealed.