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.

Simultaneous measurement of the size distribution of aerosol particles and the number of particles of each size in a flowing gaseous medium

Abstract: A method and apparatus are described for measuring the size distribution of aerosol particles in a gas stream and the number of particles of each size Particle-laden gas flows through the apparatus at a controlled velocity A group of particles located in a first region are rapidly charged by a pulsed corona discharge The group of charged particles flows downstream into a second region in which an axial electric field is applied The mobility of the charged particles through the field is a function of their charge, which in turn is a function of their size, so that the larger particles move through the second region faster and thus in less time than slow particles In this manner, particles having a common size are concentrated in an axial direction as they move downstream The magnitude of the charge on particles arriving at the downstream end of the second region is related to the elapsed time between the time of the charging pulse and the moment at which the charge is measured to indicate the particle size distribution and number of particles of each size

Semiconductor wafer temperature measuring device and method

Abstract: A probe having four spring-loaded tips contacts the backside of a semiconductor wafer in a processing machine. A current is induced across the outer tips and a voltage proportional to the sheet resistance of the wafer is measured across the inner tips. Wafer thickness is used to convert sheet resistance to bulk resistivity. Data on resistivity as a function of temperature is used to determine wafer temperature.

X-ray treatment machine having means for reducing secondary electron skin dose

Abstract: In an x-ray treatment machine a charged particle accelerator or cobalt source is provided for producing a field of high energy x-ray radiation for application to a body, for treatment thereof. The radiation machine includes collimators and field shaping structures for shaping the field of x-ray radiation applied to the body. The high energy x-ray radiation intercepted by the field shaping and collimating structures produces high energy secondary electrons by a number of different atomic processes. These energetic secondaries contaminate the shaped radiation field applied to the body being treated. The contaminating high energy electrons, if not eliminated, substantially increase the dosage of radiation delivered to the surface of the body. However, electron deflecting means, such as magnet structures, are provided for interposing in the electron contaminated field of x-ray radiation, so as to provide an electron deflecting flux for deflecting the contaminating electrons and reducing the dose due to these electrons by spreading them out more uniformly over the treated surface. In addition, an electron absorbing screen is interposed in the secondary electron contaminated radiation field for further absorbing the unwanted high energy secondary electrons.

High speed fet employing ternary and quarternary iii-v active layers

Abstract: A field effect transistor (FET) preferably employs an epitaxial layer of indium gallium arsenide as its active layer. On the surface of the active layer, ohmic source and drain contacts are spaced from respectively opposite sides of a Schottky barrier (rectifying) gate electrode. The active layer is grown over an epitaxial transition layer which is graded from gallium arsenide to indium gallium arsenide and is doped with chromium or oxygen to be semi-insulating. The transition layer is in turn formed over a bulk, intrinsic layer of gallium arsenide. High speed operation of the FET is obtainable because the active layer has excellent electron transport characteristics. Other materials suitable for the active layer are indium arsenide phosphide and indium gallium arsenide phosphide.

Magnetron sputter etching system

Abstract: A planar magnetron etching device having a movable magnetic source which is moved with respect to a substrate to cause lines magnetic flux parallel to the surface of the substrate to sweep above the surface of the substrate during the etching process.