Effect of electron collisions on steady states of plasma diodes with an electron potential barrier

Solutions corresponding to steady states of the Pierce diode are derived in the presence of collisions of electrons with background particles and reflection of electrons from the virtual cathode is investigated. Two families of solutions: Bursian and non-Bursian are explored. It is demonstrated that all non-Bursian solutions disappear when the ratio of the average collision frequency to the electron plasma frequency is of the order of 10 %. (paper)