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.

Improvement of linear accelerator depth-dose curves.

Abstract: A semiempirical analytic description of the accelerator depth-dose curve is described along with its physical explanation. The results of Monte Carlo calculations are presented and compared with experimental data to test this model. Calculations were made for different atomic number (Z) materials used as x-ray targets and flatteners, with the results showing that medium-Z materials are the logical choice. It is demonstrated empirically that D/sub max/ is a simple function of the average energy (E-bar) of the x-ray spectrum. The variation of E-bar with Z of the target and flattener is demonstrated. As a practical example, Monte Carlo calculations and experimental data for old and new Clinac/sup R/ 35 accelerators are presented.

High intensity x-ray source using bellows

Abstract: Several different embodiments of high-intensity rotating-anode X-ray tubes are shown which use a liquid or fluid-cooled rotating-­anode. No ferrofluid-type rotating joints or O-ring gasket-­type seals are required so that the interior of the tube maintains a high vacuum without pumping. A bellows (18) permits mechanical coupling to interior structures of the tube while providing a completely vacuum tight enclosure. All joints may be hard soldered or brazed together so the entire system can be baked at a high temperature during pumpdown.

Broadband linearly polarized beat-wave TE/sub m1//TE/sub 11/ mode converters

Abstract: Broadband linearly polarized waveguide mode converters have been developed to transform the high-order cylindrical TE/sub m1/ output wave from harmonic gyrotron amplifiers into the more useful TE/sub 11/ fundamental waveguide mode. The converter's corrugation period is equal to the beat between the two waves and the bandwidth is predicted to be inversely proportional to the number of periods. Four-period TE/sub 31//TE/sub 11/ and TE/sub 41//TE/sub 11/ converters with an azimuthal perturbation of m/sub c/=4 and m/sub c/=5, respectively, have yielded a peak conversion efficiency of 98% with a bandwidth greater than 3% and a one-period beat-wave converter has been designed to yield 12% bandwidth. However, it has been observed in measurements that the strong coupling in a short converter can lead to a shift of the center-frequency with an accompanying reduction of the efficiency and bandwidth. A two-period TE/sub 41//TE/sub 11/ converter with 5% bandwidth displayed a 5% frequency shift and a conversion efficiency of only 86%.

X-ray tube exposure monitor

Abstract: An X-ray tube exposure monitor for recording the emissions from a diagnostic X-ray tube A photo diode is mounted inside the X-ray tube bulkhead and detects radiation from the X-ray tube The photo diode is connected to a high gain amplifier and, in response to radiation being detected, the output of the amplifier sends an electronic signal to a microprocessor The microprocessor records the emission duration and the temperature of oil around the X-ray tube and increments an exposure count The recording and exposure count is stored in non-volatile memory which is read later by a service technician

Optoelectronic assembly including light transmissive single crystal semiconductor window

Abstract: An optoelectronic assembly obtains substantially improved coupling efficiency between small core optical fibers and small area detectors and emitters The assembly includes a housing containing an active optoelectronic device and a light transmissive single crystal semiconductor window The light transmissive single crystal semiconductor window seals the housing and physically protects the device from the environment The single crystal semiconductor window has an index of refraction higher than conventional glass windows, preferably greater than 2, in order to reduce beam spreading between the optical fiber and small area detectors or emitters The window material is preferably single crystal GaP