Friedrich Paschen

Louis Carl Heinrich Friedrich Paschen (1865 to 1947) was a German physicist, known for his work on electrical discharges, born in Schwerin in the Grand Duchy of Mecklenburg-Schwerin. He studied at the universities of Berlin and Strassburg from 1884 to 1888, became an assistant at the Academy of Münster, a professor at the Technische Hochschule Hannover in 1893 and professor of physics at the University of Tübingen in 1901. He is known for the Paschen series, a series of hydrogen spectral lines in the infrared region that he first observed in 1908, for the Paschen curve, established in an article on the potential difference needed for a spark to pass in air, hydrogen and carbon dioxide at different pressures, and for the Paschen-Back effect, in which the Zeeman effect becomes non-linear at high magnetic field. He helped explain the hollow cathode effect in 1916, served as president of the Physikalisch-Technische Reichsanstalt from 1924 to 1933, and died in Potsdam in 1947.