IMPROVED WIRE ION PLASMA GUN

摘要

An ion plasma electron gun for the generation of electron beams which exhibits electron beam dose uniformity and which is capable of varying the dose received by a material to be irradiated. Positive ions generated by a wire in a plasma discharge chamber are accelerated through an extraction grid onto a second chamber containing a high voltage cold cathode. These positive ions bombard a surface of the cathode, causing the cathode to emit secondary electrons which form an electron beam. After passing through the extraction grid in the plasma discharge chamber, the electron beam exits from the gun by way of a second grid and a foil window supported on the second grid. The gun is constructed so that the electron beam passing through the foil window has a relatively large area and uniform electron distribution which is subsantially the same as the ion distribution of the ion beam impinging upon the cathode. Means are provided for creating a pulse of secondary electrons by varying the period of time in which the secondary electrons are transmitted through the foil.