[3] After his A-level exams (Examen artium) in the summer of 1920 at the Halling School in Oslo, Widerøe left for the university of Karlsruhe, Germany, to study electrical engineering.

[1] In 1924, he returned to Norway for a short time period, working in a locomotive facility of the Norwegian State Railways, where he fulfilled his 72-day military service.

There he studied at the Technical University at Aachen, where he proposed a thesis in 1927 for an experimental betatron accelerator, incorporating the work of Swedish scientist Gustav Ising of 1924,[3][6][7] which was not successful at first.

[1][4] Thus, Widerøe instead built a linear accelerator prototype based on Isings proposal and made this the topic of his dissertation under Walter Rogowski.

Inspired by the opportunity to continue his research and promises that his brother would have a better situation in his imprisonment, he agreed to go to Hamburg and start building a German Betatron.