Varian Associates

About: Varian Associates is a based out in . It is known for research contribution in the topics: Beam (structure) & Amplifier. The organization has 2160 authors who have published 2591 publications receiving 46002 citations.

Microwave waveguide window having the same cutoff frequency as adjoining waveguide section for an increased bandwidth

Abstract: A microwave waveguide window is disclosed wherein a dielectric filled window section of waveguide is sealed across a waveguide. The window filled section of waveguide in one embodiment is dimensioned to have approximately the same low frequency cutoff wavelength as that of the adjoining sections of guide, such that the window and that of the adjoining sections of the waveguide support approximately the same waveguide transmission modes. In certain windows of the present invention, a quarter wave matching transformer portion of the dielectric window extends from the window into the adjacent waveguide sections. In other windows of the present invention, one or both adjoining sections of waveguide have a substantially lower height, such as ridged waveguide, than the dielectric filled window section and a short section of transition waveguide is interposed between the window and the adjoining lower height waveguide with the dielectric window member projecting into the transition section of waveguide.

Method for obtaining uniform etch by modulating bias on extension member around radio frequency etch table

Abstract: A method for etching a semiconductor wafer on an RF etch table employs a succession of different biases on an extension member positioned adjacent the periphery of the table. The extension member is electrically conductive, but is insulated from the etch table. The extension member is positioned with respect to the periphery of the table in a manner such that the plasma sheath induced above the etch table is continued beyond the periphery of the table, thereby eliminating the focusing of ions on the edges of an item being etched on the table. As different bias voltages are applied to the extension member, different etch profiles are experienced on the semiconductor wafer. The aggregation of etch profiles produces a more uniform overall etch.

Nonelectron emissive electrode structure utilizing ion-plated nonemissive coatings

Abstract: A nonemissive electrode structure is disclosed together with a method for fabricating same. The nonelectron emissive electrode structure includes a core member which may be made of any one of a number of different metals such as molybdenum, copper, tantalum or tungsten. A nonelectron emissive material is deposited over the core metal. The nonemissive deposited layer may be any one of a number of different materials which will provide electron emission inhibiting characteristics in the presence of surface contamination by barium and/or strontium. Examples of such electron emission inhibiting materials include titanium, chromium, zirconium, or silicon. An outer coating of carbon is formed over the emission inhibiting layer to further enhance the nonelectron emissive characteristics of the electrode. Alternatively, the nonemissive deposited layer and carbon coating may be codeposited into a single covering layer deposited over the core material. The electrode structure is especially suitable as a grid structure in an electron discharge device employing either an oxide coated cathode or a dispenser cathode of the type containing barium and/or strontium.

Broadband high-power microwave window assembly

Abstract: Broadband High-Power Microwave Window Assembly A window assembly for a hollow waveguide of circular cross-section, with improved bandwidth and cooling capability for handling high microwave power transmissions over wide frequency ranges t is disclosed. A plate or disc of dielectric of refractive index n1 extends sealingly across the waveguide and has two parallel faces which exhibit a pattern of corrugations. One of these faces is in contact with a dielectric fluid of refractive index n2, and apparatus is provided for cooling and circulating the fluid over said one face. Each of the corrugations extends into the fluid a distance proportional to the inverse of the geometric mean of the product of the refractive indices n1, n2. In a preferred embodiment, a second plate is included, separated from the first by a region in which said dielectric fluid is circu-lated, and in which at least both the faces in con-tact with the fluid are corrugated. The corruga-tions not only result in greatly improved matching over a broad band, but also greatly improved fluid flow and surface contact thereof over said one face, for enhanced cooling and thus power handling capa-bility of the window assembly.