{{short description|German physicist (1865–1947)}} {{Infobox scientist | name = Friedrich Paschen | image = Friedrich Paschen Physiker.jpg | birth_date = {{Birth date|1865|1|22|df=y}} | birth_place = Schwerin | death_date = {{Death date and age|1947|2|25|1865|1|22|df=y}} | death_place = Potsdam | known_for = Paschen–Back effect<br>Paschen series<br>Paschen's law | awards = Rumford Medal {{small|(1928)}} | workplaces = University of Tübingen | doctoral_students = Walther Gerlach | notable_students = Harrison M. Randall }} '''Louis Carl Heinrich Friedrich Paschen''' (22 January 1865 – 25 February 1947) was a German physicist, known for his work on electrical discharges. He is also known for the Paschen series, a series of hydrogen spectral lines in the infrared region that he first observed in 1908. He established the now widely used Paschen curve in his article ''"Über die zum Funkenübergang in Luft, Wasserstoff und Kohlensäure bei verschiedenen Drücken erforderliche Potentialdifferenz"''.<ref>{{cite journal | title = Ueber die zum Funkenübergang in Luft, Wasserstoff und Kohlensäure bei verschiedenen Drucken erforderliche Potentialdifferenz | author = Friedrich Paschen | journal = Annalen der Physik | volume = 273 | issue = 5 | pages = 69–75 | year = 1889 | url = | doi = 10.1002/andp.18892730505|bibcode = 1889AnP...273...69P | hdl = 2027/uc1.$b624756 | hdl-access = free }}</ref> He is known for the Paschen-Back effect, which is the Zeeman effect's becoming non-linear at high magnetic field. He helped explain the hollow cathode effect in 1916.<ref name="Paschen1916">{{cite journal|last1=Paschen|first1=F.|title=Bohrs Heliumlinien|journal=Annalen der Physik|volume=355|issue=16|year=1916|pages=901–940|issn=0003-3804|doi=10.1002/andp.19163551603|bibcode=1916AnP...355..901P|url=https://zenodo.org/record/1447321}}</ref>
==Life== Paschen was born in Schwerin, Grand Duchy of Mecklenburg-Schwerin. From 1884 to 1888 he studied at the universities of Berlin and Strassburg, after which he became an assistant at the Academy of Münster. He became a professor at the Technische Hochschule Hannover in 1893 and professor of physics at the University of Tübingen in 1901. He served as president of the Physikalisch-Technischen Reichsanstalt from 1924–33 and an honorary professor of the University of Berlin in 1925.
During the second world war he had the Chinese scientist He Zehui to stay at his house and she became like a daughter to him. With his help she was introduced to Walther Bothe who led the Kaiser Wilhelm Institute in Heidelberg.<ref>[http://cerncourier.com/cws/article/cern/47833 Zehui He: following a different road], Cern Courier, 2011, retrieved February 2015</ref>
Paschen taught in Berlin until his death in Potsdam in 1947. He is buried at the Stahnsdorf South-Western Cemetery.<ref>{{cite web|url=https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/paschen-louis-carl-heinrich-friedrich|title=Paschen, Louis Carl Heinrich Friedrich. Complete Dictionary of Scientific Biography. 2008.|publisher=Encyclopedia.com|accessdate=21 May 2018}} <http://www.encyclopedia.com></ref>
==See also== * Paschen notation * Townsend discharge
== External links == * {{FamilySearch|id=97D4-6L2|title=Louis Carl Heinrich Paschen}}
==References== {{Reflist}}
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{{DEFAULTSORT:Paschen, Friedrich}} Category:1865 births Category:1947 deaths Category:Burials at Stahnsdorf South-Western Cemetery Category:19th-century German physicists Category:People from Schwerin Category:People from the Grand Duchy of Mecklenburg-Schwerin Category:Humboldt University of Berlin alumni Category:Academic staff of the Humboldt University of Berlin Category:University of Strasbourg alumni Category:Academic staff of the University of Münster Category:Academic staff of Leibniz University Hannover Category:Academic staff of the University of Tübingen Category:Honorary members of the Russian Academy of Sciences (1917–1925) Category:20th-century German physicists