Physics and engineering of crossed-field discharge devices

The physics of devices such as the Penning cell, anode layer ion source, and cylindrical and planar magnetrons is reviewed, with particular emphasis on new developments in the field. These crossed-field discharge devices are specially designed to operate at gas pressures below 10(-2) Torr which makes them attractive for a wide range of applications. Due to effective electron confinement in crossed electric and magnetic fields some of these devices (e. g. inverted magnetron) can even run at pressures as low as 10(-10) Torr. At such low pressures the electron confinement time is much longer than the ion transit time so that the discharge is practically pure electron plasma. The review covers not only the physics of the discharges themselves, but also their interactions with electromagnetic fields. The latter allow additional control over the discharge parameters. Important historical steps in development of E x B discharge devices as well as their characteristics and differences are described and some possible future research directions are discussed.