Arthur Rudolph Berthold Wehnelt (April 4, 1871 – February 15, 1944) was a German physicist, noted for important contributions in the fields of X-ray physics, gas discharges and electron emission.
He studied physics at the Technische Hochschule Charlottenburg, and from 1893 to 1897 at the Friedrich-Wilhelms University in Berlin.
He taught as a lecturer from 1901 and associate professor of physics from 1904 at the Friedrich-Alexander University Erlangen-Nuremberg.
In this context, he developed in 1902/03 the Wehnelt cylinder, an electrode used in electron guns.
In 1904 he developed what is arguably his most important invention, the Wehnelt or oxide cathode for vacuum tubes.