Abstract: A vacuum pump is provided with at least one cylinder having a cylinder liner and a piston mounted for reciprocating movement within the cylinder liner. The piston is connected to a crankshaft for reciprocating the piston and the piston is provided with a piston head having a flat face and an upper end thereof. A valve plate having a flat surface facing the flat surface of the piston head is biased into engagement with the end of the cylinder liner whereby upward movement of the piston the flat face of the piston head makes full contact with the flat face of the valve plate to move the valve plate away from the cylinder liner. The piston is provided with two annular lip seals having an L-shaped configuration disposed in opposite directions at opposite ends of the piston in engagement with the cylinder liner.

Abstract: Extra loss is introduced in coupled cavity and klystron RF circuits by applying a surface coating to selected parts of circuit elements used in the circuits. The coating is applied in the form of a slurry, which is then sintered. The slurry comprises a mixture of an iron-base powder (such as a stainless steel) and a dielectric glass ceramic, suspended in a binder dissolved in a solvent. Circuits with the loss coating are easier to match than by other prior art techniques. The loss coating of the invention reduces the fabrication cost of coupled-cavity traveling wave tubes, while improving the performance by minimizing the gain ripple. Higher average power operation is possible, due to elimination of loss buttons previously employed in the prior art.

Abstract: An improved process for fabricating modified isoplanar integrated circuits with enhanced density incorporates a number of interactive and co-acting process steps. First, oxide isolation of epitaxial islands is effected in a two step process, forming a thin thermally grown oxide layer (32), over the surfaces of shallow trenches and then filling the shallow trenches with deposited low temperature oxide (34). Second, an enhanced single polycrystalline or polysilicon layer process uses a blanket implant, eliminates certain masking and etching steps, and defines the polycrystalline layer. Third, a new method and structure is provided for dielectrically isolating and separating contact locations on different surface levels of the integrated circuit structure adjacent to step locations between the surface levels. Finally, a new method constitutes all of the electrical contact locations for the elements of the integrated circuit structure at the same substantially isoplanar level.