Wednesday, October 24, 2012

Super Radiotron!

Irving Langmuir was an American chemist and physicist who produced numerous patents. He was awarded the Nobel Prize in Chemistry 1932 for his research in "surface chemistry". They were very excited about his work with monatomic films on tungsten and platinum filaments, and his general theory of adsorbed films. It all stepped from his invention of the gas filled tungsten lamp in 1913. He discovered that filling a tube with inert gas instead of a vacuum resulted in more brightness less blackening.  But in radio he had another contribution. It's not hard to see how the first gas-filled tungsten lamp led to the Radiotron. Guglielmo Marconi once wrote that Langmuir's 20-kilowatt tube Super Radiotron tube was  "the greatest development of the age"

Doctor Langmuir was a native Brooklynite, and graduate of Columbia University. He studied to be a metallurgical engineer, and spent three years at the University of Göttingen, Germany . There he studied under Professor Walther Nernst, inventor of the eponymous Nernst lamp. Nernst lamps did not use a tungsten (or even metallic) filament. Instead, they used a ceramic rod (a mix of zirconium oxide - yttrium oxide) which was heated to a point of incandescence. the advantage here is that unlike metals i.e. tungsten, ceramic didn't oxidize in air. That means that it didn't need to be in a vacuum. Nernst lamps were only enclosed in class to protect the hot incandescent rod from burning fingers and setting the drapes on fire. Nernst sold his patent to Westinghouse who manufactured them in America. More here.

The Radiotron Tube contains a grid, a filament, and a plate. The filament is large and rugged and the plate, supplied with a direct current of 20,000 volts, is a metallic cylinder 8 inches long and 1½ inches in diameter, sealed directly into the glass of the tube. That re-thinking of Edison's vacuum tube is probably what started Langmuir down the path of to the Radiotron.

Langmuir  worked at General Electric, from 1909–1950 and in that time advanced the fields of physics and chemistry. Not only did he invent that gas-filled tube, he also invented a hydrogen welding technique and was the first industrial chemist to become a Nobel laureate. More here.