The Duoplasmatron is an ion source in which a cathode filament emits electrons into a vacuum chamber.
[1] A gas such as argon is introduced in very small quantities into the chamber, where it becomes charged or ionized through interactions with the free electrons from the cathode, forming a plasma.
The duoplasmatron was first developed in 1956 by Manfred von Ardenne to provide a powerful source of gas ions.
The cathode works by injecting a beam of electrons with a suitable amount of energy.
In comparison to Penning ionization sources, the duoplasmatron features advantages such as less expenditure, easier handling, and a longer lifetime.