Helix Technology Corporation

Granville-phillips Company

Daniel Granville Bills

Michael Dale Borenstein

Paul C Arnold

Wilbert Leonard Porter

Stephen L Dodgen

Craig B Van Cleve

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 apparatus for measuring the differential pressure between at least two fluids including (a) first and second pressure enclosures; (b) first and second pressure deformable members where the first deformable member is sealingly connected to the first pressure enclosure and second deformable member is sealingly connected to the second pressure enclosure and the pressure deformable members are rigidly linked so as to move as one unit; (c) a frame for locating the first and second pressure enclosures in fixed relationship to one another; (d) a position sensing device for determining the displacement of the pressure deformable members relative to the frame; (e) a force balancing device including a first portion rigidly connected to the frame and a moveable second portion connected to the pressure deformable members; (f) a transducer for transducing the displacement of the first and second pressure deformable members into a force acting on the moveable second portion of the force balancing device in a direction to decrease the displacement, the first pressure deformable member including a nonflexible circular first plate sealingly connected to at least one flexible first shell of revolution where the first shell is concave on one surface thereof and said second pressure deformable member including a nonflexible circular second plate sealingly connected to at least one flexible second shell of revolution where the second shell is concave on one surface thereof.

Force balancing capacitance manometer

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.

Methods of pressure measurement

An ionization gauge including a source of electrons; an open anode defining an anode volume, where the source of electrons is disposed outside the anode volume; a plurality of ion collector electrodes disposed within the anode volume; a plurality of axially extending anode support posts for supporting the open anode, the anode support posts being electrically connected to the open anode; and the plurality of ion collector electrodes being respectively located sufficiently close to the plurality of axially extending anode support posts so as to substantially repel the electrons from the anode support posts.

Miniature ionization gauge utilizing multiple ion collectors

Controller circuitry and method for controlling the operation of an ionization gauge having a source of electrons, an anode, an ion collector electrode. Circuitry is provided (a) for providing an electron emission current from the electron source (b) for measuring the heating power W.sub.X of the electron source to obtain a measured value of the heating power at an unknown pressure P.sub.X and (c) measuring the ion current to the collector electrode to obtain a measured value of the positive ion current i.sub.+X at the unknown pressure. A memory is also provided for storing at least one equation for pressure, the pressure equation being obtained from a reference gauge by measuring the current i.sub.+cal to the positive ion collector electrode, the electron emission current i.sub.-cal from the electron source and the heating power W.sub.cal of the electron source of the reference gauge at selected calibration pressures P.sub.cal and selected heating powers W.sub.cal of the electron source of the reference gauge, the equation for pressure being in the form of P=f(i.sub.+ /i.sub.-,W). Moreover, a calculator responsive to the stored equation for pressure and the measured values of positive ion collector current i.sub.+X and heating power W.sub.X of the electron source is provided for calculating a pressure indication P.sub.XI when the predetermined pressure gauge is exposed to the unknown pressure P.sub.x at an emission current i.sub.-cal of the electron source, the pressure indication being calculated according to the equation P.sub.XI =f(i.sub.+X /i.sub.-cal, W.sub.X). Means are also provided such that, for a given pressure of the gas and cathode temperature, the temperature of the internal surfaces of the gauge will be substantially repeatable over time and reproducible gauge to gauge.

Ionization gauge and method of using and calibrating same

An apparatus for measuring the differential pressure between at least two fluids including (a) first and second pressure enclosures; (b) first and second pressure deformable members where the first deformable member is sealingly connected to the first pressure enclosure and second deformable member is sealingly connected to the second pressure enclosure and the pressure deformable members are rigidly linked so as to move as one unit; (c) a frame for locating the first and second pressure enclosures in fixed relationship to one another; (d) a position sensing device for determining the displacement of the pressure deformable members relative to the frame; (e) a force balancing device including a first portion rigidly connected to the frame and a moveable second portion connected to the pressure deformable members; and (f) a transducer for transducing the displacement of the first and second pressure deformable members into a force acting on the moveable second portion of the force balancing device in a direction to decrease the displacement.

Controller circuitry and method for controlling the operation of an ionization gauge having a source of electrons, an anode, an ion collector electrode. Circuitry is provided (a) for providing an electron emission current from the electron source (b) for measuring the heating power W.sub.X of the electron source to obtain a measured value of the heating power at an unknown pressure P.sub.X and (c) measuring the ion current to the collector electrode to obtain a measured value of the positive ion current i.sub.+X at the unknown pressure. A memory is also provided for storing at least one equation for pressure, the pressure equation being obtained from a reference gauge by measuring the current i.sub.+cal to the positive ion collector electrode, the electron emission current i.sub.-cal from the electron source and the heating power W.sub.cal of the electron source of the reference gauge at selected calibration pressures P.sub.cal and selected heating powers W.sub.cal of the electron source of the reference gauge, the equation for pressure being in the form of P=f(i.sub.+ /i.sub.-, W). Moreover, a calculator responsive to the stored equation for pressure and the measured values of positive ion collector current i.sub.+X and heating power W.sub.X of the electron source is provided for calculating a pressure indication P.sub.XI when the predetermined pressure gauge is exposed to the unknown pressure P.sub.X at an emission current i.sub.-cal of the electron source, the pressure indication being calculated according to the equation P.sub.XI =f (i.sub.+X /i.sub.-cal, W.sub.X). Means are also provided such that, for a given pressure of the gas and cathode temperature, the temperature of the internal surfaces of the gauge will be substantially repeatable over time and reproducible gauge to gauge.

A device for determining a pressure of gas in an evacuated chamber including a cylinder positioned in fluid communication with the evacuated chamber with the cylinder forming a compressed gas chamber, a reciprocating piston received within the cylinder and mounted for reciprocal movement therein, a port or valve for providing selective fluid communication between the compressed gas chamber and the evacuated chamber is disclosed. A drive mechanism is provided for reciprocating the piston between a retracted position, where the compressed gas chamber communicates with the evacuated chamber, and an extended position where communication between the compressed gas chamber and the evacuated chamber is interrupted, the position being a position where a pressure transducer determines that a predetermined pressure differential between the chambers has been reached. In the preferred embodiment, a stepper motor is used to measure a distance travelled by the piston at the point where the predetermined pressure differential is reached. Utilizing these parameters, a processor then determines the pressure of the gas within the evacuated chamber.

Wide range vacuum gauge

Ionization gauge and method of operating same where the gauge may be of the Bayard-Alpert type and include a shield which completely encloses the electron source, the anode, and the collector electrode so that potentials external to the shield do not disturb the electric charge distribution within the shielded volume to thus stabilize the sensitivity of the gauge. The ionization gauge is further characterized by the following features which may be present either alone or in combination including: (a) the anode is provided with end caps which extend radially inward at least 25% of the radius of the anode but not more than 75% of the radius; (b) the ion collector has a diameter of not less than 0.015 in. and not more than 0.080 in.; (c) the ion collector extends at its free end at least through one of the partial end caps of the anode; (d) the electron source is not substantially longer axially than the region within the anode volume in which the electric field is predominantly directed radially inward and where the electron source is located substantially only adjacent to the foregoing region; (e) the anode is provided with a substantially uniformly transparent grid structure in the regions where the electrons enter the anode volume and where they exit from the anode volume. Moreover, the above features may be utilized in other hot cathode ionization gauges where, for example, the above features (a) and (d) may be utilized in triode gauges.

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Boulder, CO, United States of America

Daniel Granville Bills