Hollow cathode duoplasmatron for reactive gas ions

A duoplasmatron using a hollow cathode rather than a head cathode has been developed for a series of instruments. These instruments use a primary ion beam to bombard a sample and create secondary ions that are subsequently mass analyzed. The composition of an unknown sample can then be determined by the mass spectra produced by such an instrument. Some of the requirements of an ion source for this application are (1) high brightness at less than 20 keV, (2) low energy spread to reduce the chromatic aberration of the primary beam, (3) low gas flow rates so that differential pumping may be avoided, and (4) the ability to generate positive and negative ions from reactive gases