| 摘要 |
An evacuated tube has a face plate and a tubular body with at least a portion of the body having a circular cross section. In the evacuated tube is an electron emissive electrode adapted to release electrons in response to impinging photons or photoelectrons, means for collecting the electrons and an anode. The electron emissive electrode is cup shaped, having an approximate circular top opening through which photons or photoelectrons enter to impinge on the electrode, a circular rim around the periphery of the top opening, and a side opening through which the electrons pass to exit from the electrode. The inside of the electrode is lined with electron emissive material. The electrode is positioned in the portion of the tubular body having the circular cross section with the rim of the electrode substantially parallel to the plane of the circular cross section and having a diameter substantially the same as the diameter of the circular cross section, and with the top opening of the electrode facing the face plate. The means for collecting the electrons is positioned laterally adjacent to the electrode between the side opening and the tubular body.
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