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Abstract In this work we report the results of imaging and spectroscopic measurements of the optical emission spectrum of a negative nanosecond-pulsed cryogenic discharge in liquid nitrogen. With the application of a lower electric field, the discharge first ignites as a ‘faint glow’ around the high-voltage needle electrode, but when the applied electric field reaches the transition value of around 5 MV cm−1the discharge mode switches to a negative in-liquid streamer. The optical emission spectrum of the discharge is populated by the molecular nitrogen emission bands, and their analysis shows that the pressures and temperatures of the negative streamers in liquid nitrogen are at least of few tens of atmospheres and around 140–150 K. The results of this study demonstrate similarity of positive and neganive streamers in cryogenic in-liquid plasma conditions.
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Optical characterization of nanosecond-pulsed discharge in liquid nitrogen
Abstract We report the optical characterization of nanosecond-pulsed plasma ignited directly in liquid nitrogen. Using imaging and optical emission spectroscopy, we estimate neutral temperatures and densities, as well as local electric field values, and the obtained results indicate that the discharge develops via streamer (‘electronic’) mechanism. We show that millimeter-scale plasma propagates in liquid nitrogen at velocities of ∼500 km s−1with the corresponding required local electric fields as high as 25 MV cm−1, while the estimated local electric fields in the ‘core’ of the discharge are around 6–8 MV cm−1(corresponding to reduced electric field values of 600–1000 Td). The neutral and electron densities in the ‘main body’ of the discharge were estimated using broadened argon lines, indicating that the neutral densities in the near-electrode region are around 1020cm−3(tens of atmospheres), while the maximum recorded temperature is just a few tens of degrees above the surrounding liquid. Electron densities were estimated to be ∼1017cm−3, about two orders of magnitude lower than those measured for water discharge.
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- Award ID(s):
- 2108117
- PAR ID:
- 10507885
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics D: Applied Physics
- Volume:
- 57
- Issue:
- 32
- ISSN:
- 0022-3727
- Format(s):
- Medium: X Size: Article No. 325204
- Size(s):
- Article No. 325204
- Sponsoring Org:
- National Science Foundation
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