Partial pressure gauge assembly for process contaminant detection using photoionization and associated method
Inventors
Briglin, Shawn M. • Vollero, Michael F. • Wiley, John Gordon
Assignees
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Publication Number
US-12203887-B2
Publication Date
2025-01-21
Expiration Date
Abstract
A photoionization sensor assembly includes a housing defining a chamber with a first end and an opposing second end and being permeable to the analyte gas and non-analyte gases. A radiation source is structured to emit photons into the chamber. A first, second and third electrode are positioned in the chamber. The photons ionize the analyte gas, are insufficient to ionize the non-analyte gases, and causing ejection of photoelectrons from the third electrode. A controller is structured to receive a measurement of a total pressure and electrically bias the electrodes to collect the photoelectrons on the first and second electrodes in a ratio dependent on the total pressure. The controller is structured to determine the ratio of photoelectrons that are collected on the first and second electrodes at the total pressure and determine an amount of electrical current due to ionization by correcting the measured current using the determined ratio.
Core Innovation
The invention relates to a sensor assembly for measuring a total pressure of a gas, using a housing that defines a chamber with a first end and an opposing second end, where the chamber is permeable to molecules of the gas surrounding the housing. The assembly includes a radiation source configured to emit photons into the chamber, and three electrodes positioned toward opposite ends and within the chamber. The photons emitted into the chamber cause an ejection of photoelectrons from the third electrode.
A controller electrically biases the first, second, and third electrodes to attract and collect the ejected photoelectrons on the first and second electrodes in a ratio dependent on the total pressure of the gas. The photoelectrons generate an electrical current on the first and second electrodes, and the controller measures the electrical current generated on those electrodes. The controller determines the total pressure of the gas based on the electrical current generated on the first and second electrodes.
The invention further provides a photoionization sensor assembly configured to measure an analyte gas in a presence of non-analyte gases, where photons ionize at least some molecules of the analyte gas while being insufficient to ionize molecules of the non-analyte gases. The emitted photons strike the third conductive electrode to eject photoelectrons that are collected on the first and second conductive electrodes in a ratio dependent on the total pressure of the analyte gas and the non-analyte gases. The controller uses the determined ratio to subtract an electrical current caused by the photoelectrons from the measured electrical current to determine an amount of electrical current due to ionization of the analyte gas.
Claims Coverage
The document includes four independent claims that cover two inventive features: determining total pressure from photoelectron collection currents in a three-electrode photoionization sensor, and measuring analyte gas ionization in the presence of non-analyte gases by correcting measured current using a pressure-dependent photoelectron collection ratio.
Photoelectrons ejected and collected in pressure-dependent ratio to determine total pressure
Electrically bias the first, second and third electrodes such that the ejected photoelectrons are attracted toward and collected on the first and second electrodes in a ratio dependent on a total pressure of the gas; measure the electrical current generated on the first and second electrodes; determine the total pressure of the gas based on the electrical current generated on the first and second electrodes.
Photoionization of analyte gas with insufficient photons for non-analyte gases and current correction using photoelectron ratio
Ionize at least some molecules of the analyte gas with emitted photons that are insufficient to ionize molecules of the non-analyte gases; attract and collect photoelectrons on the first and second conductive electrodes in a ratio dependent on the total pressure; determine the ratio of ejected photoelectrons collected at the total pressure; and determine an amount of electrical current due to ionization of the analyte gas by correcting the measured current using the determined ratio to subtract an electrical current caused by the photoelectrons from the measured electrical current.
Photoelectron collection ratio-based correction to remove photoelectron current and measure analyte gas ionization
Electrically bias the first, second and third conductive electrodes such that the photoelectrons are attracted toward and collected on the first and second conductive electrodes in a ratio that is dependent on the total pressure of the analyte gas and the non-analyte gases; measure an electrical current generated on the first and second conductive electrodes; determine the ratio of the ejected photoelectrons collected on the first and second conductive electrodes at the total pressure; and determine an amount of electrical current due to ionization of the analyte gas by correcting the measured current using the determined ratio to remove an electrical current caused by the photoelectrons.
Photoelectron-induced current measurement to determine total pressure
Electrically bias the first, second and third conductors such that the ejected photoelectrons are attracted toward and collected on the first and second electrodes in a ratio that is dependent on a total pressure of the gas; measure the electrical current generated on the first and second electrodes; and determine the total pressure of the gas based on the electrical current generated on the first and second electrodes.
The claim coverage is focused on a photoionization sensor architecture in which photons eject photoelectrons from a third electrode and a controller biases multiple electrodes so collected photoelectron currents form a pressure-dependent ratio. For analyte gas measurements, the claims further require using that ratio to correct measured current by subtracting the photoelectron-caused current, leaving current due to ionization of the analyte gas. For total pressure measurements, the measured photoelectron-induced current on the first and second electrodes is used directly to determine total pressure.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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