Brooks Automation Gmbh

Helix Technology Corporation

Granville-phillips Company

Michael Dale Borenstein

Daniel Granville Bills

Paul C Arnold

Larry K Carmichael

Paul M Rutt

Stephen C Blouch

Richard A Knott

A measurement instrument having a processor, a first sensor and a second sensor. The processor is adapted to output a measurement signal embodying a measurement of a physical quantity. The first sensor and second sensor are connected to the processor and are operable to generate respectively first and second measurements of the physical quantity. The processor defines a first measurement range within which the measurement signal is dependent on the first measurement and not the second measurement. The processor defines a second measurement range within which the measurement signal is dependent on the second measurement and not the first measurement. The first and second ranges meet at a predetermined transition. The first and second measurements are different at the transition and the measurement embodied in the measurement signal crosses the transition without an abrupt change.

Measurement instrument and method

Pressure measurement instrument and method

A method and apparatus for operating a multi-hot-cathode ionization gauge is provided to increase the operational lifetime of the ionization gauge in gaseous process environments. In example embodiments, the life of a spare cathode is extended by heating the spare cathode to a temperature that is insufficient to emit electrons but that is sufficient to decrease the amount of material that deposits on its surface or is optimized to decrease the chemical interaction between a process gas and a material of the at least one spare cathode. The spare cathode may be constantly or periodically heated. In other embodiments, after a process pressure passes a given pressure threshold, plural cathodes may be heated to a non-emitting temperature, plural cathodes may be heated to a lower emitting temperature, or an emitting cathode may be heated to a temperature that decreases the electron emission current.

Method and apparatus for maintaining emission capabilities of hot cathodes in harsh environments

A combination vacuum gauge provides simultaneous absolute and differential pressure measurements over a wide-range of pressures ranging from atmospheric pressures to ultrahigh vacuum by processing the readings of (i) an absolute high vacuum gauge (e.g., an ionization gauge and/or a heat-loss sensor) and an absolute or a differential low vacuum gauge (e.g., a diaphragm sensor) exposed, through a common port, to pressures in a measurement region, and (ii) a barometric absolute pressure sensor exposed to the ambient atmosphere outside the measurement region. The barometric absolute pressure sensor reading may be used to convert the differential vacuum gauge reading from uncalibrated differential pressure to calibrated absolute pressure or to convert the absolute vacuum gauge reading from absolute pressure to differential pressure.

Wide-range combination vacuum gauge

A method and apparatus are provided for achieving nearly perfect temperature compensation of a heat-loss vacuum gauge over its full pressure range. A voltage is measured across a sensor leg, a sensor leg and a temperature compensating leg connected together in series, or a sensor leg and a fixed resistive leg coupled together in series. A voltage is also measured across a subleg of the temperature compensating leg. The temperature compensating leg may include a temperature sensitive subleg and a temperature stable subleg connected together in series. The sublegs may include one or more temperature sensitive and/or temperature stable elements. The measured voltages are combined to produce temperature independent pressure indications over a pressure range. Three-dimensional curve-fitting or similar techniques may be used to combine the measured voltages.

Technique for improving Pirani gauge temperature compensation over its full pressure range

In a resistively heated heat-loss pressure gauge, electrical current is switched between a sensing element and a compensating element at different duty cycles. As a result, the sensing element is heated relative to the compensating element. A fixed resistance is placed in series with at least the compensating element. The current source applies current to heat the sensing element to a temperature at which the resistance of the sensing element matches the combined resistance of the compensating element and the fixed resistive element.

Method of operating a resistive heat-loss pressure sensor

A combination vacuum gauge provides simultaneous absolute and differential pressure measurements over a wide range of pressures ranging from atmospheric pressures to ultrahigh vacuum by processing the readings from an absolute high vacuum gauge (e.g., an ionization gauge and/or a heat-loss sensor), a differential low vacuum gauge providing a differential relative to ambient pressure (e.g., a diaphragm sensor), and a barometric absolute pressure sensor exposed to the ambient atmosphere outside the measurement region. The barometric absolute pressure sensor reading is used to convert the differential vacuum gauge reading from uncalibrated differential pressure to calibrated absolute pressure.

A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element and the compensating element for applying current through the elements. The current through the sensing element is substantially greater than the current through the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

Apparatus and methods for heat loss pressure measurement

A heat loss gauge for measuring gas pressure in an environment includes a resistive sensing element and a resistive compensating element. The resistive compensating element is in circuit with the sensing element and has temperature response and physical characteristics substantially matching those of the resistive sensing element and is exposed to a substantially matching environment. An electrical source is connected to the sensing element for applying current to heat the sensing element relative to the compensating element. Measuring circuitry is connected to the sensing element and the compensating element for determining gas pressure in the environment to which the sensing element and compensating element are exposed based on electrical response of the sensing element and the compensating element.

An improved Pirani gauge has a small-diameter wire sensing element, coplanar with a small-diameter wire compensating element, with two parallel flat thermally conductive plates spaced from the sensing and compensating elements. The sensing and compensating elements and their connections have the same physical dimensions, thermal properties and resistance properties. The connections have large thermal conductances to a uniform temperature region and the elements are located in the same vacuum environment. A DC heating current is used and confined to only the sensing element. A relatively small AC signal is used to sense bridge balance. A simplified three-dimensional pressure compensation formula provides accurate compensation while simplifying the collection of calibration data. The improved gauge provides significant advancements in Pirani gauge accuracy, production cost, and package size.

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Boulder, CO, United States of America

Michael Dale Borenstein