Focus head for X-ray tube, has emitter surrounded by blocking electrodes that are applied with blocking potential independent of one another, so that areas of emitting surface are blocked with respect to electron emission

摘要

The head (1) has a longitudinal emitter (2) e.g. flat and spiral emitters, including an emitting surface and surrounded by a set of blocking electrodes (4, 6, 8) that are applied with a blocking potential independent of one another, so that partial areas of the respective emitting surface are blocked with respect to an electron emission in operating condition. The emitter possesses an oblong form, and the blocking electrodes are arranged at longitudinal sides of the emitting surface such that the blockable partial areas lie one behind the other in a longitudinal direction of the emitter. An independent claim is also included for a method for operating a focus head.