ŽÁČEK, August
* 13. 1. 1886, Dobešice near Protivín, Czech Republic
† 26. 10. 1961, Prague, Czech Republic
Physicist
Until 1905 Ž. attended grammar school in Česke Budějovice and then studied mathematics and physics at the Faculty of Charles University in Prague. In 1910 he graduated with the thesis "On the capillary phenomena”. The next two years he studied at the University of Göttingen with Simon, who was concerned with the oscillations caused by the light arch. Then he was appointed assistant at the city Physical Institute of Charles University, where he in 1918 habilitated with “The study on the capacitor range”. After completing military service, which he served in a new transmitter in Petřín in Prague, the University appointed him associate professor at the newly founded Department of Applied Physics in 1921. During the winter of 1921/22, he worked as a trainee in Lund, Sweden in laboratories of Charles Manne Georg Siegbahn, who later won the Nobel Prize (1924). From 1922 onwards he taught experimental physics at Charles University as a full professor. In the following years he was concerned mainly with the characteristics of a magnetron, discovered and described by Albert W. Hull in 1921. Hull described magnetron as an electronic tube, the anode current of which flows through the magnetic field rather than grid potential. Unlike Hull Ž. demonstrated that the critical value of magnetic field in magnetron under the influence of the periodic motion of electrons between the cathode and the anode leads to very rapid oscillations. He noted that the wavelength of this electronic oscillation depends on the magnetron parameters. This dependence was named “Ž.’s relation”. He filed a patent for the application of this discovery in 1924 in Czechoslovakia and Germany. In 1931/32 he was the Dean at the Faculty of natural sciences of Charles University. After years of closing down the Czech universities during the Second World War, he was again able to teach after 1945, yet only for a short period of time, as he was suspended and forcibly retired after the communists took power in 1948. Prior to 1939 he was a member of the Czechoslovak Academy of Sciences and Arts and Masaryk University.
