Bródy, Imre

Though he achieved numerous research results in several fields of physics and industrial application, his name is primarily known as the inventor of the krypton lamp.

Between 1909 and 1913, he was a student at the Faculty of Mathematics and Natural Sciences of University of Sciences in Budapest

and he obtained his teacher's diploma in 1915.

He wrote his doctoral dissertation on the chemical constant of monoatomic gases. First he taught high school, then he became an assistant professor in the department of applied physics at the University of Sciences. Early in his career he accomplished valuable theoretical work investigating specific heat and molecular heat.

Between 1920 and 1922, he worked with Max Born at the university in Göttingen

. During less than two years he published 7 papers, the four most important ones of which were written with Born. Max Born and Imre Bródy investigated the interaction of phonons by applying the perturbation calculation method. With this the Born-Kármán model became the basic theoretical tool of crystal dynamics.

He studied the invariant integrals of quantum mechanics and fluctuations responsible for phase transformation.

In 1923, he returned home and became the scientist of the Research Laboratory of United Incandescent-Lamp and Electrical Co. Ltd., of which he remained a leading research worker till the end of his life.

The first task to creating krypton lamps was to develop a proper method for producing krypton at a low price. Bródy jointly with Ferenc Kőrösi, and with Pál Selényi's assistance, found that krypton could be found in the atmosphere at a concentration of 1.5 millionths. On the basis of thermodynamic considerations, he solved the production of krypton with Mihály Polányi's assistance. The essence of their idea was that they liquefied only 10% of a quantity of air and blew the pre-cooled remainder through this, in this way, washing out the majority of the krypton. So it was only this 10% that had to be fractionated. Production of krypton based on this invention started at Ajka in 1937.

Krypton lamps were presented at the Budapest Industrial Fair in 1936 and appeared on foreign markets during that year. He conducted long experiments with Emil Theisz to find the optimum form of krypton lamps. At last they succeeded in achieving a significant saving of krypton by reducing the dimensions of bulbs.

Bródy was an active researcher working on new light source problems. He dealt with the effect of the length and weight of the filament; the deposition of tungsten dust; the fitting of iron wire to glass; the lifetimes of different types of bulbs; the burning of bulbs at fluctuating voltage; and, together with Mihály Neumann (János Neumann's brother), the possibility of creating pressurised bulbs.

He remained with his family after the German occupation of Hungary in 1944, and despite of the immunity the factory provided for him, he succumbed to certain death. He died on December 20, 1944 in Mühldorf as a victim of nazis.

The Roland Eötvös Physical Society

named a prize after him, thus commemorating his life's work.

krypton lamp

In a gas-filled bulb its life-time is limited by the evaporation of the filament. Thermal diffusion is a significant cause of this process. Wolfram with high atomic weight emitted from the filament gets into the filling gas (usually a mixture of argon and nitrogen) of low atomic weight, and moves towards the wall of the bulb dimming the glass.
However, if the atomic weight of the filling gas is also high, this process slows down. Since the atomic weight of krypton (84) is closer to that of wolfram (183) than to that of nitrogen (18) or argon (40), the life-time of bulbs filled with krypton can be extended or rather a better performance can be achieved, provided that the heating temperature and the light efficiency are the same.