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Managing photon flux in a miniaturized photoionization detector

Journal Article · · Journal of Applied Physics
DOI:https://doi.org/10.1063/5.0193595· OSTI ID:2572037
Miniaturized photoionization detectors (PIDs) are used in conjunction with gas chromatography systems to detect volatile compounds in gases by collecting the current from the photoionized gas analytes. PIDs should be inexpensive and compatible with a wide range of analyte species. One such PID is based on the formation of a He plasma in a dielectric barrier discharge (DBD), which generates vacuum UV (VUV) photons from excited states of He to photoionize gas analytes. There are several design parameters that can be leveraged to increase the ionizing photon flux to gas analytes to increase the sensitivity of the PID. To that end, the methods to maximize the photon flux from a pulsed He plasma in a DBD-PID were investigated using a two-dimensional plasma hydrodynamics model. The ionizing photon flux originated from the resonance states of helium, He(3P) and He(21P), and from the dimer excimer He2*. While the photon flux from the resonant states was modulated over the voltage pulse, the photon flux from He2* persisted long after the voltage pulse passed. Several geometrical optimizations were investigated, such as using an array of pointed electrodes. However, increasing the capacitance of the dielectric enclosing the plasma chamber had the largest effect on increasing the VUV photon fluence to gas analytes.
Research Organization:
University of Michigan, Ann Arbor, MI (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
SC0020232
OSTI ID:
2572037
Journal Information:
Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 14 Vol. 135; ISSN 0021-8979; ISSN 1089-7550
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

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