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.

Shuttleless toroidal core winder

Abstract: Disclosed is an apparatus for simultaneously winding multiple strands of wire into turns about a toroidal core in rapid fashion. The apparatus includes a U-shaped wire receiving channel having a semi-circular portion with a gap and a pair of open-ended legs. The ends of the channel legs are positioned adjacent opposite sides of a rotatably mounted drum which is driven by a resilient endless belt engaging approximately one half of its annular outer surface. A toroidal core is supplied and rigidly supported in the gap by a core feeding mechanism. A grooved gap crosser is thereafter extended through the central opening of the core to bridge the gap and complete the channel. A pair of pinch roller type feed/brake mechanisms propel and guide the leading ends of the wires into the channel, through the core opening, and up one channel leg to the drum. There the wires are frictionally held between the drum and the belt and they are positively driven into the other channel leg, through the core opening, and back to the drum. Continued feeding of the wire results in the formation of a coil having a plurality of vertically stacked, oval-shaped loops which extend through the core opening and are alternately made of different ones of the wires. Thereafter, staggered braking of the trailing ends of the wires causes the loops to be successively peeled radially inwardly from the channel and the drum as the coil is continuously circulated. The loops are tightened into turns about the core as it is slowly rotated about its axis by the core feeding mechanism. First and second shear mechanisms cut off the trailing and leading ends of the wires at the beginning and end of the winding operation, respectively.

Growth rate monitor for molecular beam epitaxy

Abstract: A light source with appropriate optics focusses light on the wafer surface during deposition, while a nearby collector is biased to collect photoemitted electrons from the growing surface. A pico ammeter can be used to convert the small oscillatory current detected to a substantial voltage signal which can be recorded or processed by computer or other sutiable device. The light must contain wavelengths at energies close to or greater than the energy of the photoemission threshold. The detected photoemitted electron signal has an oscillatory component occurring due to the growth of epitaxial layers. This oscillation has frequency 1/τ, where τ is the monolayer accumulation time.