| 摘要 |
An ion plasma electron gun for the generation of large area electron beams with uniform electron distribution. Positive ions generated by a wire in a plasma discharge chamber are accelerated through an extraction grid into 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 and 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 a uniform electron distribution which is substantially the same as the ion distribution of the ion beam impinging upon the cathode. Control of the generated electron beam is achieved by applying a control voltage between the wire and the grounded housing of the plasma chamber to control the density of positive ions bombarding the cathode. |
