Electron image tube having a trapping space for loose particles.

摘要

For the trapping of any loose particles remaining in the envelope of an electron image tube after manufacture or subsequently formed therein, the envelope has a trapping space (49 or 50) which is readily accessible to the loose particles but wherefrom the loose particles can escape only with great difficulty, and which is such that particles trapped therein will not substantially adversely affect normal operation of the tube. The entrance of the trapping space suitably is a funnel-like slit (46 or 48) directed towards the interior of the trapping space (49 or 50). The trapping space (49, 50) is preferably in a region of the envelope free of strong fields in normal operation of the tube.