Life and Work of Rolf Wideröe by © Pedro Waloschek,     => Contents

Box 7:  The War of the Patents

Max Steenbeck (see Box 6) and his then superior Rüdenberg (who, like Wideröe, developed relays for power stations) had already submitted a patent on the stability of electron orbits in betatrons in 1933 [Ru33]. From the text it is apparent that they were aware of Slepian's patent [Sl22] (in those days, and until after World War II, it was not yet mandatory to make precise references to `previously performed or published work' when submitting patents).

Siemens subsequently asked Steenbeck to run a secret project to construct such a tube. He had read Wideröe's thesis [Wi28] in the meantime, and thus took into consideration the 2:1 ratio between steering and accelerating magnetic fields. The machine of 1934/35 was able to accelerate electrons to 1.8 MeV. However, the number of accelerated electrons was far less than had been expected, so the work was stopped. But during the course of this investigation Siemens submitted a second patent for Steenbeck in Germany [St35], the USA [St36] and in Austria, in which protection by patent for both the stability condition and the 2:1 ratio, among other things, was specifically applied for. General Electric USA applied to Siemens for a licence to use this patent and, according to Steenbeck, this was granted on December 6, 1941 (shortly before America entered the War).

Kerst (University of Illinois) had already published his first betatron results in October 1940 [Ke40a] and immediately afterwards he submitted the betatron for US-patenting (for General Electric) [Ke40b]. It is very similar to Steenbeck's patent, although clearer in its formulation. Kerst's famous work on the 2.3 MeV betatron followed it in 1941 [Ke41a]. Kerst makes no mention of Steenbeck's patents in these publications (neither does he mention his own), but he does refer to the work of Wideröe and Walton, and later also to Breit, Tube and Jassinski. It is unusual for patents to be mentioned in scientific publications.

Following Kerst's famous paper, Siemens, prompted by Steenbeck, took up the construction of betatrons again and appointed X-ray-engineer Konrad Gund to do this. Siemens were able to assert their rights in 1954 and received compensation from BBC for their alleged use of Steenbeck's patents.

During 1943/44 Wideröe submitted ten patents on the betatron for BBC and there would be more later.