Varian Associates

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

Optical wavelength shifting by traveling-wave electrooptic modulation

Abstract: Optical wavelength shifting of 1.054-nm laser pulses in excess of +or- 10 wavenumbers (+or- 300 GHz) was demonstrated. The wavelength shifter consists of synchronous microwave and optical waveguides fabricated monolithically on LiNbO/sub 3/. An optical pulse experiences a constant refractive index gradient that travels with the pulse and causes the wavelength shift. >

Field effect transistor having source and gate electrodes on opposite faces of active layer

Abstract: By positioning the source and gate electrodes on the opposite faces of the active layer, these electrodes can be brought closer together and may have their adjacent edges mutually aligned or even overlapping. The series source resistance and channel resistance can be greatly reduced, because of this closer spacing, which can not be attained when the electrodes are coplanar. By also locating the drain electrode on the same side of the active layer as the source, the source-to-drain spacing can be significantly reduced, reducing channel length and improving the high frequency performance of the transistor. Further, because the electrodes are located on both sides of the active layer, it is possible to provide a large area contact on the bottom, or substrate, side of the epitaxial wafer structure which can advantageously be used to provide a low thermal and electrical resistance connection for the source contact, for example. Finally, the fact that one or more of the electrodes can be contacted from the bottom of the wafer makes possible the simple parallel interconnection of electrodes to easily form multiple element power transistors.

An electronic braking device for asynchronous motors

Abstract: The invention relates to an electronic braking device for asynchronous motors particularly for asynchronous motor equipped with magnetic suspensions such as those employed in turbomolecular pumps, comprising a circuit for recovering the kinetic energy of the rotor during the decelerating phase due to the absence of feeding electric current from the mains, which is adapted to return an electric current that can be used for the emergency feeding the magnetic suspensions (8). Such circuit can further comprise an auxiliary battery (10) for feeding a circuit (9) controlling the magnetic suspensions (8) during the final phase of the stopping cycle of the motor (5) caused by the absence of mains current.

Some Aspects of Electron Beam Optics and X-Ray Production with the Linear Accelerator

Abstract: Part I A mathematical presentation of linear accelerator fundamental design parameters leads to optimization formulae for X-ray output and operational stability. A narrow spread of electron energies is desirable in most linear accelerator applications and especially when post-acceleration beam bending is utilized to project a stable high energy X-ray beam at right angles to the accelerator waveguide. Part II Some consideration is given to electron source optics and an analysis of a chopped prebunched injection system is presented together with a comparison of different types of buncher design with emphasis on obtaining narrow energy spectrum small cross-section electron beams. A method of analysing prebunched injection current and buncher acceptance characteristics is described