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How magnetron unlocked the future of safe aviation across the globe

radar magnetron machine
London Heathrow airport in 1917 by Ben Brooksbank

Clockwise. Radar Oscilloscope, Randall and Boot – early magnetron, Heathrow Airport 1970s

The magnetron, a vacuum tube that produces microwave radiation, was being developed by a number of countries prior to WW2.

The critical breakthrough came in terms of achieving sufficient power. In 1940, at the University of Birmingham in the UK, John Randall and Harry Boot developed a working prototype of a cavity magnetron that produced about 400 W.

Within a week this had improved to 1 kW, and the addition of water cooling saw a jump to 10 kW over the next few months and then an exponential leap to a massive 25 kW.

Britain put this technology to good use in its radar system for its air defense. Here, a set of signals generated from a range of coastal towers known as Chain were read with oscilloscopes. Edwards was involved in the production of components for these oscilloscopes. In fact, vacuum tubes were used extensively.

After the war, research continued into the range of uses for the magnetron and the foundational technology was there for the development of air traffic control, the critical aspect of managing the fast-growing volume of air traffic. Air traffic control, the management in real-time, of thousands of aircraft each hour using a handful of runways, is the undisputed contributor to the remarkable record of air travel safety.

For an understanding of how this innovation unlocked the exponential growth in safe air travel, consider Heathrow airport alone. In its inaugural year of 1946, it managed 63,000 passengers. By 1986 that number exceeded 31 million passengers, handling more than 300,000 flights a year.