Abstract: The collector wall axially coextensive with the expanding beam of electrons includes at least portions thereof which extend inwardly to closely approach the periphery of the beam of electrons at several axially spaced planes. In its simplest form this structure consists of a series of annular baffle plates each having a central aperture of a diameter only slightly larger than the diameter of the beam at the axial plane in the collector where the baffle plate is located. These baffle plates have been found to substantially reduce the number of secondary (impact-produced) electrons which return from the collector to the interaction sections of the linear beam microwave tube. As a result spurious signals and noise caused by back-streaming secondary electrons are significantly reduced.

Abstract: A grid electrode for an electron tube with planar electrodes consists of a planar array of fine wires mounted on a support frame. The support frame has a circular outside rim and interconnected interior elements dividing the area inside the rim into three or more separated apertures. The interior elements include radial elements connected to non-radial elements, forming a mechanically rigid structure with good heat conduction to the outside rim which resists buckling out of its plane when differentially heated.

Abstract: In an image tube, a photocathode is disposed to receive a photon image for emitting into the tube a corresponding electron image which is accelerated by an accelerating anode and focused upon an output device, such as a fluorescent screen or a microchannel electron multiplier. A gating electrode is interposed along the beam path between the anode and the output device. The potential difference between the photocathode and the gating electrode is periodically pulsed such that the gating electrode is sufficiently negative relative to the potential of the photocathode for reflecting the image electrons passing through the anode back to the anode for collection thereof and thus for gating off the electron image to the output device. This potential difference may be pulsed by pulsing the photocathode positive with respect to the gating electrode or by pulsing the gating electrode negative with respect to the photocathode.