Speaker
Mr
Bart Klarenaar
(Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands)
Description
Efficient reduction of CO$_2$ to CO is a key step in the process of storing renewable energy in the form of hydrocarbon fuels. This process is believed to be most efficient when selectively exciting the asymmetric-stretch vibration of CO$_2$. We study the temperature dynamics of CO$_2$ by *in situ* rotational Raman spectroscopy in a pulsed glow discharge. The cylindrical plasma reactor (23 cm length, 2 cm inner diameter) is operated under flowing conditions in the millibar range, with a 10–50 mA plasma current. The plasma is pulsed with a cycle of 5 ms on, 1 ms off, while the residence time of the gas is in the order of seconds.
Raman scattered light is collected from the focal point of a pulsed Nd:YAG laser (532 nm, 100 mJ/pulse, 100 Hz), focused inside the reactor. Rayleigh scattered light is rejected using a volume Bragg grating, after which the remaining light enters a spectrometer and is detected by an ICCD camera. Raman spectra are taken at different time-points during the discharge cycle, as well as at different positions along the longitudinal axis of the reactor. The spectra are fitted to determine the rotational temperature and the molecular concentrations of CO$_2$, CO and O$_2$, exploiting the unique Raman ‘fingerprints’ of these molecular species.
First analysis of a measurement at 6.66 mbar and 50 mA shows that temperatures range from 400 K at the start of the 5 ms plasma pulse to 900 K at the end. Variations along the longitudinal axis stay within ±50 K. Furthermore, the concentrations of CO$_2$, CO, and O$_2$ at the center of the reactor are determined to be 82%, 9%, and 9%, respectively, not varying strongly during the pulse cycle.
Primary author
Mr
Bart Klarenaar
(Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands)
Co-authors
Mrs
Ana Sofia Morillo-Candas
(Laboratoire de Physique des Plasmas, Ecole Polytechnique-CNRS-Univ Paris-Sud-UPMC, Palaiseau, France)
Mr
Dirk van den Bekerom
(Dutch Institute for Fundamental Energy Research, Eindhoven, The Netherlands)
Mrs
Marija Grofulovic
(Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal)
Mr
Mark Damen
(Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands)
Mr
Olivier Guaitella
(Laboratoire de Physique des Plasmas, Ecole Polytechnique-CNRS-Univ Paris-Sud-UPMC, Palaiseau, France)
Mr
Richard Engeln
(Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands)
Mr
Richard van de Sanden
(Dutch Institute for Fundamental Energy Research, Eindhoven, The Netherlands)
