Abstract: A wide aperture permanent magnet structure which is useful in creating a highly uniform longitudinal or solenoidal magnetic field in the working region of the magnet and in which the aperture of the structure can be equal in cross-sectional area to the working region of the magnet. The geometry and magnetization direction of the constituent magnets are chosen to maximize the uniformity of the longitudinal or solenoidal magnetic field in the working region of the magnet while minimizing the overall volume and weight of the structure as well as eliminating the need for magnetic pole pieces made of iron or other high permeability materials. The invention can take the form of a cylindrical shell of permanent magnets to create a solenoidal magnetic field, or a parallel surface arrangement to create a longitudinal magnetic field.

Abstract: The electron impact surface of an anode/collector is coated with a carbon nanotube coating to reduce the production of secondary electrons and, concomitantly, to suppress the formation of neutral gases and plasma. A carbonizable resin is first applied to the electron impact surface, followed by a coating comprised of carbon nanotubes. The coating is pyro-bonded to the surface by heating the anode/collector to over 700° C. in a non-oxidizing atmosphere. Next, the anode/collector is heated to over 1000° C. while a low-pressure hydrocarbon gas, for example, methane, is flowed over the carbon nanotube coating. The gas decomposes and creates a smooth, non-porous, rigid surface on the carbon nanotube coating. The anode/collector is then heated in a vacuum to evaporate any residual water in the carbon nanotube coating.

Abstract: A vacuum tube having its anode/collector coated with carbonized resin plus pyrocarbon material to reduce out-gassing and secondary electron emission and the method of coating the anode/collector.

Abstract: A vacuum tube having its anode/collector coated with carbon nanotube-based material in which five percent or more of the carbon nanotubes are aligned parallel to the anode/collector's surface.

Abstract: A vacuum tube having its anode/collector coated with carbon nanotube-based material in which five percent or more of the carbon nanotubes are aligned parallel to the anode/collector's surface.

Abstract: A vacuum tube having its anode/collector coated with carbonized resin plus pyrocarbon material to reduce out-gassing and secondary electron emission and the method of coating the anode/collector.