Spectroscopic characteristics of H-alpha/O-I atomic lines generated by nanosecond pulsed corona-like discharge in deionized water

0489522 - ÚFP 2019 RIV GB eng J - Článek v odborném periodiku
Pongrác, Branislav - Šimek, Milan - Člupek, Martin - Babický, Václav - Lukeš, Petr
Spectroscopic characteristics of H-alpha/O-I atomic lines generated by nanosecond pulsed corona-like discharge in deionized water.
Journal of Physics D-Applied Physics. Roč. 51, č. 12 (2018), č. článku 124001. ISSN 0022-3727. E-ISSN 1361-6463
Grant CEP: GA ČR(CZ) GA15-12987S
Institucionální podpora: RVO:61389021
Klíčová slova: underwater discharge * nanosecond pulsed discharge * time-resolved emission spectroscopy
Obor OECD: Fluids and plasma physics (including surface physics)
Impakt faktor: 2.829, rok: 2018
http://iopscience.iop.org/article/10.1088/1361-6463/aaabb1/meta

Basic emission fingerprints of nanosecond discharges produced in deionized water by fast rise-time positive high-voltage pulses (duration of 6 ns and amplitude of + 100 kV) in a point-to-plane electrode geometry were investigated by means of time-resolved intensified charge-coupled device (ICCD) spectroscopy. Time-resolved emission spectra were measured via ICCD kinetic series during the discharge ignition and later phases over the 350-850 nm spectral range with fixed, either 3 ns or 30 ns, acquisition time and with 3 ns or 30 ns time resolution, respectively. The luminous phase of the initial discharge expansion and its subsequent collapse was characterized by a broadband vis-NIR continuum emission evolving during the first few nanoseconds which shifted more toward the UV with further increase of time. After similar to 30 ns from the discharge onset, the continuum gradually disappeared followed by the emission of H-alpha and O-I atomic lines. The electron densities calculated from the H-alpha profile fit were estimated to be of the order of 10(18)-10(19) cm(-3). It is unknown if the H-alpha and O-I atomic lines are generated even in earlier times (before similar to 30 ns) because such signals were not detectable due to the superposition with the strong continuum. However, subsequent events caused by the reflected HV pulses were observed to have significant effects on the emission spectra profiles of the nanosecond discharge. By varying the time delay of the reflected pulse from 45 to 90 ns after the primary pulse, the intensities of the H-alpha/O-I atomic lines in the emission spectra of the secondary discharges were clearly visible and their intensities were greater with shorter time delay between primary and reflected pulses. These results indicate that the discharges generated due to the reflected pulses were very likely generated in the non-relaxed environment.
Trvalý link: http://hdl.handle.net/11104/0283923