Multi-chambered acoustic sensor for determination gas composition
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Assignees
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Publication Number
US-9217663-B2
Publication Date
2015-12-22
Expiration Date
Abstract
A sound velocity sensor is defined by a hermetic multi-chambered enclosure for containing flowing gases and mixtures of gases. The contained flowing gases are acoustically excited and the acoustic energy is measured over a fixed distance between a first sending end of the enclosure and a receiving end. The speed of sound of the gases are determined by comparing the energy transmitted through the flowing gases at various frequencies so as to precisely determine the resonant frequency of the gases flowing through the enclosure. In accordance with the present design, the chambers of the enclosure include internal transition shapes therebetween for optimizing the transmission of acoustic energy through the flowing gases and also enhancing one or more additional resonant modes at higher useful frequencies. The transition shapes used in connection with the sensor can be at least one of parabolic, hyperbolic, linear and exponential in nature.
Core Innovation
The invention relates to a sound velocity sensor for analyzing the gas concentration of a flowing mixture of gases. The sensor includes a hermetic enclosure with an interior that defines a resonator chamber and includes a pair of acoustic cavities separated by a constricted region. The enclosure is configured so that gas flows through the resonator chamber, with the flowing mixture including nitrogen as a primary carrier gas.
Acoustic driving means are provided at a first sending end of the enclosure to transmit an acoustic signal through the gas mixture, and receiving means at a second receiving end receive the acoustic signal for processing by a processor. The sensor detects a resonant frequency of the flowing gas mixture and determines the composition based on resonant behavior. The inwardly curved and tapering shape of a first acoustic cavity extending from the sending end and the opposing outwardly curved and tapering shape extending to the receiving end are used to optimize transmission of acoustic energy through the flowing gas mixture.
The invention further enhances at least one additional resonant mode at higher useful frequencies by using a narrow constricted region between the first and second acoustic cavities. The disclosure also describes continuous transition/tapering shapes between adjacent cavities to reduce acoustic impedance loss while improving acoustic-energy transmission. The sensor is described for a reactor utilizing MOCVD or CVD processes, including temperature control of the enclosure and flowing gas mixture, and operating with nitrogen as the primary carrier gas.
Claims Coverage
The document contains two independent claims. The claim set is centered on a nitrogen-primary-carrier hermetic, multi-cavity resonator sound velocity sensor and a corresponding manufacturing method that forms continuous transition areas between adjacent acoustic cavities to improve acoustic-energy transmission.
Hermetic multi-cavity sound velocity sensor with nitrogen carrier gas
A sound velocity sensor including a hermetic enclosure with an interior defining a resonator chamber, a pair of acoustic cavities separated by a constricted region, gas flowing means for flowing a gas mixture including nitrogen as a primary carrier gas through the resonator chamber, acoustic driving means at a first sending end, receiving means at a second receiving end, a processor configured to process the received acoustic signal, and means for detecting a resonant frequency to determine the composition of the gas mixture.
Inwardly and outwardly curved tapering cavities with narrow constricted region for additional resonant modes
The sensor is configured so that a first acoustic cavity is defined by an inwardly curved and tapering shape extending from the first sending end and an opposing second acoustic cavity is defined by an outwardly curved and tapering shape extending to the second receiving end with a narrow constricted region between the cavities to optimize transmission of acoustic energy through the flowing gas mixture and enhance at least one additional resonant mode at higher useful frequencies.
Method of manufacturing a sound velocity sensor with continuous transition areas between adjacent cavities
A method for manufacturing a sound velocity sensor for a reactor utilizing MOCVD or CVD processes using a flowing gas mixture including nitrogen as a primary carrier gas, the method including providing a hermetic enclosure having a sending end, a receiving end, and a plurality of adjacently coupled acoustic cavities defining a resonator chamber; providing an acoustic signal generator and an acoustic signal receiver for transmitting and receiving an acoustic signal through the flowing gas mixture; and providing continuous transition areas between at least two of the plurality of adjacently coupled acoustic cavities for improving the transmission of acoustic energy through the flowing gas mixture between the sending end and the receiving end.
Across the independent claims, the core coverage is a hermetic enclosure resonator with nitrogen-primary-carrier gas and acoustic sending/receiving to determine resonant frequency for composition analysis, where inwardly/outwardly curved tapering cavities with a constricted region enhance additional higher-frequency resonant modes. The manufacturing claim complements this by specifying continuous transition areas between adjacent acoustic cavities to improve acoustic-energy transmission.
Stated Advantages
Optimizing transmission of acoustic energy through the flowing gas mixture.
Enhancing at least one additional resonant mode at higher useful frequencies.
Improving the transmission of acoustic energy through the flowing gas mixture between the first sending end and the second receiving end.
Documented Applications
Analyzing the gas concentration/composition of a flowing gas mixture in a reactor utilizing MOCVD or CVD processes, using nitrogen as a primary carrier gas.
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