Claims
- 1. A gas emission spectrometer for analyzing and measuring low concentration levels of one or more gas/vapor impurities in a gas stream under continuous flow conditions comprising: an electric discharge source; means for feeding a gas sample through said electric discharge source at a preselected flow rate; power supply means for applying an alternating voltage across said discharge source at a predetermined excitation frequency and having sufficient peak voltage to sustain an electric discharge and generate emissive radiation from said gas stream over a wide radiation spectrum; means for optically filtering said emissive radiation to form an optical signal having a narrow radiation emission bandwidth corresponding to the stronger emission wavelength(s) of a preselected gas/vapor impurity in said gas sample; means for converting said optical signal into a corresponding electrical signal and analog amplifier means for selectively amplifying said electrical signal within a narrow frequency range centered at substantially twice said excitation frequency, wherein said gas stream impurity is selected from the group consisting of nitrogen and methane, a base gas is argon, said impurity to be analyzed is nitrogen and at said excitation frequency of 255 Hz or higher.
- 2. A gas emission spectrometer as defined in claim 1 wherein said nitrogen below 20 ppb can be detected.
- 3. A gas emission spectrometer as defined in claim 1 wherein said analog amplifier means is a lock-in analog amplifier.
- 4. A gas emission spectrometer as defined in claim 1 wherein said electric discharge source is a silent electric discharge tube.
- 5. A gas emission spectrometer as defined in claim 1 wherein said base gas is selected from the group consisting of argon, helium, krypton and mixtures thereof.
Parent Case Info
This application is a Continuation of prior U.S. application Ser. No. 08/384,043 filing date Feb. 6, 1995, now abandoned, and which is a continuation of application Ser. No. 08/036,163 filing date Mar. 24, 1993, now U.S. Pat. No. 5,412,467.
US Referenced Citations (7)
Non-Patent Literature Citations (2)
Entry |
Holman et al., "Optical Emission Spectroscopy with a Microwave-Induced Plasma in a Sealed Microtube", Tazanna, vol. 29, No. 5, May 1992, pp. 419-421. |
"Emission Spectromeyric Method and Analyzer for Traces of Nitrogen in Oxygen" Analytical Chemistry, vol. 34, No. 10, Sep. 1962, pp. 1254-1260, Fay, Homer, Mohr, Paul H. and Cook, Gerhard A. |
Continuations (2)
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Number |
Date |
Country |
Parent |
384043 |
Feb 1995 |
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Parent |
36163 |
Mar 1993 |
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