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.

Pulsed RF excited spectrometer having improved pulse width control

Abstract: RF excitation for a spectrometer is obtained by pulse width modulating an RF carrier to produce the desired broadband RF exciting spectrum. The RF excitation includes a train of composite RF pulses, each composite pulse having a primary pulse portion of a first RF phase and a second pulse portion of a second RF phase opposite that of the first. In this manner, the finite rise and fall times of the primary pulse portion are compensated for by the corresponding rise and fall times of the secondary pulse portion. The primary pulse portion is lengthened by an amount equal to the secondary pulse portion so that the secondary pulse portion cancels the added primary pulse portion. In a spectrometer the compensating second pulse component removes certain undesired side bands of the RF excitation caused by the finite rise and fall times of the applied RF pulses. The compensating second pulse component removes certain undesired side bands associated with each of the resonant lines of the excited resonance spectrum, thereby simplifying the resonance spectrum of the sample under analysis, particularly for wide band RF excitation.

Photovoltaic cell employing lattice matched quaternary passivating layer

Abstract: A photovoltaic cell has an active portion comprising at least one active layer of a IIIA-VA compound having a p-n junction adjacent an upper surface thereof and an overlying epitaxially grown passivating layer of the quaternary alloy AlGaAsP. The passivating layer has a substantially higher bandgap than the active layer so that it is transparent to photons to which the active layer is sensitive. The lattice constant of this passivating layer can be made the same as that of the active layer, thereby to improve efficiency and device performance by reducing surface recombinations of generated carriers, such that a greater percentage of generated carriers will reach the p-n junction and provide useful output electrical energy. The active portion comprises a GaAs layer covered by an AlGaAsP passivating layer, and the AlGaAsP passivating layer can be lattice matched to the GaAs layer.

Anisotropic pyrolytic graphite heater

Abstract: A heater for an indirectly heated vacuum tube cathode is formed of anisotropic pyrolytic graphite in which current passes through the graphite in the "c" direction.