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Institution

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.
Topics: Beam (structure), Amplifier, Wafer, Cathode, Resonance


Papers
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Journal ArticleDOI
TL;DR: In this paper, a simple technique is described for obtaining exact solutions to the cubic equation which results from the PERT constraint on standard deviation, together with the expression for the mode of the beta distribution, to determine graphically the specific values of the parameters of a beta distribution associated with any particular set of PERT estimates.
Abstract: After reviewing the beta distribution and its properties, a simple technique is described for obtaining exact solutions to the cubic equation which results from the PERT constraint on standard deviation. These solutions are then used, together with the expression for the mode of the beta distribution, to determine graphically the specific values of the parameters of a beta distribution which may be associated with any particular set of PERT estimates. Expressions are derived for approximate values of these parameters in terms of the PERT estimates explicitly, and a comparison is made of the exact and approximate values. The PERT approximation concerning expected time is examined and confirmed to be an excellent simple approximation for the exact value of the associated beta distribution. It is concluded that the beta distributions associated with PERT are not necessarily as restricted, and the differences between the PERT values of expected time and standard deviation and the exact values for the associated beta distribution are not as great, as has previously been indicated in the literature.

28 citations

Patent
31 Jan 1975
TL;DR: In this paper, a grid-controlled electron source comprises an apertured grid spaced in front of a thermionic cathode, where the cathode is made non-emissive by a bonded surface layer of non emissive material such as zirconium.
Abstract: A grid-controlled electron source comprises an apertured grid spaced in front of a thermionic cathode. Areas of the cathode directly behind the grid conductors are made non-emissive by a bonded surface layer of non-emissive material such as zirconium. On porous metal cathodes impregnated with active emitting material the metal surface may be sealed with a dense layer of inactive metal under the non-emissive layer to prevent chemical reaction of the latter with the emitting material. Methods of depositing the surface layers in the desired pattern include coating the cathode's entire large-scale surface contour, followed by machining small concave dimples into the surface, thereby removing the non-emissive layer from the dimpled surfaces from which small beamlets of electrons are focused between the grid conductors without grid interception. Another method is to mask the desired non-emissive areas with an apertured mask having solid elements registered with the desired positions of the grid conductors. The surface behind the mask apertures is coated with an inactive powder, then the mask is removed and the non-emissive layer or layers deposited in the uncoated, previously masked paths. Lastly, the inactive powder is removed, uncovering the emissive surface areas.

28 citations

Journal ArticleDOI
TL;DR: In this article, two isomeric 2,4,6-trimethylpiperidines have been purified by preparative VPC and shown by PMR spectroscopy to have the cis (2,4), cis (4, 6), cis(2,6)-stereochemistry.

28 citations

Patent
12 May 1982
TL;DR: In this paper, an efficient relatively high-power inductive output linear electron beam tube with broadband capabilities is disclosed which is density modulated with a grid applying to the beam an RF modulating signal.
Abstract: An efficient relatively high-power inductive output linear electron beam tube with broad-band capabilities is disclosed which is density modulated with a grid applying to the beam an RF modulating signal. The grid has a large active area which may be of the order of ten square inches, is closely spaced one-twentieth the grid diameter or less to a thermionic cathode, and is comprised of a plurality of curved thin narrow elongated members. With the aid of an annular anode downstream of the grid, the beam is accelerated by DC potential of at least several kilovolts. A high-isolation input signal means includes adjacent but physically and electrically isolated wide-diameter, axially reduced annular cathode and grid lead means for leading both the DC beam-accelerating potential into the cathode, and the modulating RF signal into the grid with minimal impedance. A grid support means at one end of the grid peripherally engages the grid with a resilient deformable contact member to facilitate differential expansion without grid distortion while accurately maintaining the close grid to cathode spacing. The resulting density modulation forms the beam into correspondingly high-density moving bunches of electrons. An axial drift tube means encloses the beam, extends to a collector, and is interrupted by a gap. A coaxial resonant cavity about the drift tube, and into which the gap opens allows the bunches passing closely past the gap to induce efficiently in the cavity a VHF, UHF or microwave output signal corresponding to the modulating signal, but with an output power of at least a kilowatt.

28 citations

Journal ArticleDOI
TL;DR: In this paper, powder X-ray diffraction analysis and resistivity measurements are presented to examine changes in the electronic structure in a narrow composition range near the metal-insulator transition.

28 citations


Authors

Showing all 2160 results

NameH-indexPapersCitations
Richard R. Ernst9635253100
Fred E. Regnier8841225169
Norbert Schuff8828025442
James S. Hyde7941235755
Carl Djerassi77152337630
Ray Freeman7326922872
Robert Kaptein7243624275
Minghwei Hong5851514309
Jesse L. Beauchamp5527510971
Herbert Kroemer522379936
Hans J. Jakobsen492748401
James N. Eckstein421686634
Ivan Bozovic311285060
John Glushka31763004
Gary Virshup241132374
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20171
20161
20122
20111
20104
20093