HR: 1330h
AN: AE32A-0158 [PDF]
TI: NOx Production in Laser -Induced Plasma as a Function of Dissipated Energy
AU: * Rahman, M
EM: Mahbubur.Rahman@hvi.uu.se
AF: Division for Electricity and Lightning Research, The Department of Engineering Sciences, The Źngstr”m
Laboratory, Uppsala University, Box 534, Uppsala, SE-751 21
Sweden
AU: Cooray, V
EM: Vernon.Cooray@hvi.uu.se
AF: Division for Electricity and Lightning Research, The Department of Engineering Sciences, The Źngstr”m
Laboratory, Uppsala University, Box 534, Uppsala, SE-751 21
Sweden
AB:
Lightning has been identified as a potentially important natural source of nitrogen oxides (NOx =NO+NO2) and thus several
laboratory experiments have been conducted to measure the NOx production as a function of energy dissipated in sparks and
laser plasma discharges. Chameides et al. [1977] measured NOx production in air subjected to a centimetre long spark by
chemiluminescenc and derived a yield of (61) 1016 molecule J-1. The sparks were generated by a 35 kV
electrostatic generator, yielding an energy of 36 mJ per spark. Levine et al. [1981] measured NOx production in air using
chemiluminescent technique from several centimetre long sparks having a discharge energy of 12 kJ, which is more than a five
order of magnitude energy increase compared to the energy produced in Chemeides experiment and derived a yield of
(52) 1016 molecule J-1. Hill et al. [1988] investigated also the production of NO in atmospheric coronas
using a specially designed plasma reactor operated at a pressure of 0.1 MPa and a temperature of 300 K and found a yield of
NO to be (1.40.7)1016 molecule J-1. Wang et al. [1998] employed sparks with lightning like peak currents of
up to 30kA, a spark of 4 cm long at atmospheric pressure and found that the production was about (15-401016) molecule
J-1. Navarro-Gonz lez et al. [2001] simulated lightning in the laboratory by a laser-induced plasma generated by a pulsed
Nd.YAG laser at 1064 nm and found a yield of NO to be 1.50.51017 molecule J-1. Rehbein et al. [2001]
measured NOx from a 0.5-2.0 cm long sparks in the energy range of 0.5-2.5 J by chemiluminescenc and derived a yield of
(2.970.2)1016 molecule J-1. An experiment on the production of NOx from a DC corona discharge maintained by
applying a high voltage to the central wire of a coaxial metal cylinder, has also been conducted by Rehbein et al. For the
estimated energy dissipated in the discharge of about 0.4 mJ it has been found that the NOx yield was slightly higher for the
positive corona and the NOx production was in general two orders of magnitude smaller than that of spark discharges
(3-5) 1014 molecule J-1. Here an experimental study on the production of NOx as a function of dissipated
energy in laser-produced plasma in air is presented. A plasma was produced by focusing a (60-180)mJ, 5-ns, 532-nm pulse from
a Q-switched Nd:YAG laser. The results show that the produced NOx molecules per joule in the case of laser plasma at 532 nm
is comparable to the case of electrical discharges. The results also show that the NO and NOx production rates are linearly
correlated to the dissipated plasma energy, within the studied energy range. From the results one can observe that the laser
plasma with energy in the range of 13-99 mJ generates 6.71016 NOx molecules per joule and 4.61016 NO
molecules per joule.
Reference
Chameides W L, et. al.J Atmos Sci 1977;34:143-9.
Hill R. D., et. al. Ind. Eng. Chem. Res. 1988;27, 1264-9.
Levine J S, et. al. Geophys Res Lett 1981;8:357-60.
Navarro-Gonz lez R. et. al. Geophys. Res. Lett. 2001;28(20):3867-70
Rehbein N.et. al. J. Electrostatics 2001;51-52:333-9
Wang Y et. al. J Geophys Res 1998;103(D15):19149-59.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting