An improved flow measurement device is provided in a flow path for direct measurement of flow. An internal heat source solves the problem of heat transfer in conventional mass flow meters. The heat transfer associated with the internal heater forms the basis of flow measurement, and improved accuracy is achieved. The flow measurement device advantageously eliminates the introduction of inaccuracies, bypass errors, or inaccurate assumptions that are inherent in a conventional bypass structure. The present measurement device eliminates the need for one or more bubblers and thus overcomes bubbler pressure sensitivity and the bubbler requirement for exact (and unstable) gas vapor saturation of conventional flow measurement. The flow measurement device works equally well with gases, liquids or mixtures of gases and liquids and provides greater control over flow rates with very high degree of precision.
Pinch Valve Suited For Metals And Other Rigid Materials
A pinch valve is described wherein the critical flow path is modified to form a space between two opposing metal disks that transition between an open and a closed state. The disks are characterized by a spring constant and act like a diaphragm. A closure force is applied externally to completely close the disks and truncate flow, while providing a substantially perfect seal. Removal of the external force enables the disks to spring open and initiate flow. The pinch valve advantageously eliminates valve bodies, dead space, moving parts and seals, such as elastomers, that are subject to wear and corrosion.
Formation Of A Silicon Sheet By Cold Surface Casting
Metallurgical grade silicon or high purity silicon beads developed from a fluidized bed process are melted in a cooled aluminum crucible, such that a non wetted interface is created between the molten silicon and a cooled supporting substrate that includes a surface layer of substantially inert aluminum oxide. It is believed that the molten silicon does not wet the surface of the supporting substrate and the surface of the supporting substrate does not chemically interact with the silicon. It is shown that, in spite of the enormous temperature difference, molten silicon (ca. 1450 C. ) can be stabilized, by appropriate energy control, in direct (but non-wetted) contact with cold (ca. 40 C. ) material such as aluminum.
High Reflectivity Atmospheric Pressure Furnace For Preventing Contamination Of A Work Piece
A furnace incorporating a novel thermal design is disclosed. Heating element temperature is reduced compared to conventional designs while providing a precisely controllable process temperature in the range 1000-1400 degrees centigrade. A plurality of Kanthal heating elements are arranged in a planar array as close to the work as possible, thus approximating an isothermal condition with respect to the work. The process chamber is made of aluminum and its internal surfaces are highly polished to reflect heat. The chamber walls have built in active cooling to carry away non-reflected heat and preserve high reflectivity. The heating elements are modular to facilitate removal and replacement without disassembly of the furnace. The configuration of the heating elements is linear rather than coiled and the temperature is monitored directly by measuring the electrical resistance of the Kanthal wires.
High Temperature Heating Element For Preventing Contamination Of A Work Piece
A modular heating element that facilitates removal and replacement without disassembly of a furnace provides a precisely controllable process temperature in the range 1000-1400 degrees centigrade. The configuration of the heating element is linear rather than coiled, and the temperature is monitored directly by measuring the electrical resistance of KANTHAL, or other like Fe Cr Al wire encased in an aluminum ceramic sleeve that provides mechanical support and seals the heating element wire against oxidation, thereby increasing operational temperature and prolonging service life.
Single Body Injector And Method For Delivering Gases To A Surface
Jay B. DeDontney - Santa Cruz CA Nicholas M. Gralenski - Santa Cruz CA Adam Q. Miller - Santa Cruz CA
Assignee:
Watkins-Johnson Co. - Palo Alto CA
International Classification:
C23C 1600
US Classification:
118718
Abstract:
A single body injector for delivering gases to a surface. The injector includes a single elongated block with one or more passages formed in the block and communicating with a gas delivery surface via thin channels which extend between the passages and the gas delivery surface. Metering tubes may be placed in the passages to control the profile of the gases delivered.
Atmospheric Pressure Chemical Vapor Deposition Apparatus
Lawrence D. Bartholomew - Santa Cruz CA Nicholas M. Gralenski - Aptos CA Michael A. Richie - Santa Cruz CA Michael L. Hersh - Boulder Creek CA
Assignee:
Watkins-Johnson Company - Palo Alto CA
International Classification:
C23C 1646 C23C 1654
US Classification:
118719
Abstract:
A conveyorized atmospheric pressure chemical vapor deposition apparatus having a heated muffle and a conveyor belt for conveying objects to be coated through said muffle. At least one chemical vapor deposition zone is provided in the muffle. An injector assembly is also provided for uniformly injecting first and second reactant gases in the deposition zone across the width of the conveyor belt and against the surfaces of the objects to be coated. The gases exit from slots connected to distribution plenums. Polished cooled surfaces are used on the injector assembly to minimize deposition of chemicals thereon.