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.

The quality of high-energy X-ray beams.

Abstract: Supplement 17 of the British Journal of Radiology is a survey of central-axis depth doses for radiotherapy machines, patterned largely on BJR Supplement 11 published some 11 years earlier. Inspection of the high-energy X-ray depth doses for a 10 x 10 cm field at an SSD of 100 cm disclosed large differences between the two sets of data, especially for qualities above 8 MV. For example, a depth dose of 80% at 10 cm is rated at about 19 MV according to BJR Supplement 11, and 23 MV according to BJR Supplement 17. It was found that the Supplement 17 depth-dose data above 8 MV were erratic, but that the Supplement 11 data could be represented by an analytical expression, providing a unique means of assigning MV quality. It was also found that the dose-weighted average energy of the filtered beam plotted smoothly against depth dose. For dosimetric purposes, it is suggested that this parameter be used as a true measure of beam quality, removing the discrepancies introduced by the use of nominal MV for this purpose.

Wafer lifting and holding apparatus

Abstract: An automatic sputtering apparatus for coating semiconductor wafers uses shuttle wafer carriers and elevators to handle wafers within the apparatus. The wafer carrier has a hole in the center. One side of the wafer carrier is opened, thereby forming a throat in the shuttle wafer carrier in the form of the letter C. The elevator has a cantilevered shaft. The upper part of the shaft of the elevator is centered under the wafer while the lowest part of the cantilevered shaft is under a point outside the wafer carrier. The connecting portion of the shaft passes through the throat of the wafer carrier as the wafer is lifted. Since the lifting portion of the shaft is outside the wafer carrier, the shuttle can move with the elevator in the up position. The pedestal for holding the wafer on the elevator is equipped with arms which project upward at an angle to the horizontal, thereby confining the wafer to a pedestal.

Standing-wave linear accelerator

Abstract: A standing-wave linear charged particle accelerator is disclosed which comprises a plurality of interlaced substructures, with each substructure having a plurality of accelerating cavities disposed along the particle beam path and having side cavities disposed away from the beam path for electromagnetically coupling the accelerating cavities. A standing radio-frequency electromagnetic wave is supported in each substructure, with the wave in each substructure being phase with respect to the wave in every other substructure so that the particle beam will experience a maximum energy gain throughout its path through the accelerator. This interlaced substructure configuration minimizes the transit time of the particles across the gap of each accelerating cavity and makes it possible to operate the accelerator without radio-frequency breakdown at a power level that provides a substantially higher average value of the accelerating electric field along the beam path than has heretofore been obtainable.

Compression seal for elastomeric septum

Abstract: A sealing fixture in combination with a cap member provides a fluid-tight compression seal between an elastomeric septum and a tubular body. The septum is disposed transversely on a first end of the sealing fixture, which is of cylindrical configuration with an axial bore. A second end of the sealing fixture fits over the tubular body. The cap member covers the septum by being screwed down over a threaded portion of the outer wall of the sealing fixture. An aperture is provided in the cap member through which an injection device can be inserted to puncture the septum so as to deliver a quantity of fluid to, or to remove a quantity of fluid from, the tubular body via the bore in the sealing fixture. An outer wall portion of the sealing fixture adjacent the first end thereof is tapered inwardly to form a sharp junction with an inner wall portion of the sealing fixture. This inner wall portion adjacent the first end of the sealing fixture is parallel to the axis of the bore. As the cap member is screwed down over the first end of the sealing fixture, the sharp junction cuts into the septum. An edge portion of the septum overhanging the junction is compressed between the cap member and the tapered outer wall portion of the sealing structure, thereby providing a compression seal while leaving the central portion of the septum relatively stress free.

Frequency modulated selected ion species isolation in a quadrupole ion trap

Abstract: A method of isolating selected ion species in a quadrupole ion trap mass spectrometer is disclosed. One or more ranges of masses to be eliminated from the ion trap are ejected by applying a supplemental dipole excitation waveform, sparsely populated with frequency components, while the trapping field is modulated. The spacing of the frequency components in the supplemental excitation waveform varies across the range of frequencies in the waveform. Preferably, the frequency range is divided into a plurality of subranges, and the spacing of the frequency components in each of the subranges is constant. A method of creating a master set of frequencies used for generating a supplemental excitation waveform is also shown. Likewise, a method of calculating edge frequencies defining a gap in the mass spectrum that is excited by the supplemental waveform is also shown. Modulation of the trapping field may be varied while the supplemental excitation waveform is applied to change the width of the gap in the mass spectrum.