Microwave interferometry (MWI) is a nonintrusive diagnostic technique, capable of measuring small quantities of electrons present in a flame plasma. In this paper, a 94 GHz microwave interferometer is characterized and validated to perform robust and reliable measurements of electron concentrations in thermal and nonthermal plasmas in a shock tube. The MWI system is validated first by measuring the refractive index of a dielectric material. Subsequently, the system is used for measuring electron densities during the thermal ionization of argon and krypton in shock tube experiments. The measured activation energies are in good agreement with both the measured values from previous studies and theoretical values. The MWI system is finally used for measuring electron density time-histories in fuel oxidation experiments in the shock tube. The electron density profile of methane combustion shows a peak at the ignition time which agrees with pressure measurements. Experimental electron histories are also in overall agreement with predictions of the methane ion chemistry model.
REFERENCES
1.
A.
Feng
and Z.
Munir
, “The effect of an electric field on self-sustaining combustion synthesis: Part I. Modeling studies
,” Metall. Mater. Trans. B
26
, 581
–586
(1995
).2.
K. E.
Shuler
and J.
Weber
, “A microwave investigation of the ionization of hydrogen-oxygen and acetylene-oxygen flames
,” J. Chem. Phys.
22
, 491
–502
(1954
).3.
H. F.
Calcote
, “Ion and electron profiles in flames
,” Symp. (Int.) Combust.
9
, 622
–637
(1963
).4.
T. I.
Cox
, V. G. I.
Deshmukh
, D. A. O.
Hope
, A. J.
Hydes
, N. S. J.
Braithwaite
, and N. M. P.
Benjamin
, “The use of Langmuir probes and optical emission spectroscopy to measure electron energy distribution functions in RF-generated argon plasmas
,” J. Appl. Phys.
20
, 820
–831
(1987
).5.
K. A.
Aadim
, A. A.-K.
Hussain
, N. K.
Abdalameer
, H. A.
Tawfeeq
, and H. H.
Murbat
, “Electron temperature and density measurement of plasma jet in atmospheric pressure
,” Int. J. Novel Res. Phys. Chem. Math.
2
, 28
–32
(2015
).6.
G. G.
Gifford
, “Applications of optical emission spectroscopy in plasma manufacturing systems
,” Proc. SPIE
1392
, 454
–465
(1990
).7.
D. M.
Devia
, L. V.
Rodriguez-Restrepo
, and E.
Restrepo-Parra
, “Methods employed in optical emission spectroscopy analysis: A review
,” Ing. Cienc.
11
, 239
–267
(2015
).8.
E.
Carbone
and S.
Nijdam
, “Thomson scattering on non-equilibrium low density plasmas: Principles, practices and challenges
,” Plasma Phys. Controlled Fusion
57
, 014026
(2015
).9.
M. A.
Cappelli
, N.
Gascon
, and W. A.
Hargus
, Jr., “Millimetre wave plasma interferometry in the new field of a hall plasma accelerator
,” J. Phys. D: Appl. Phys.
39
, 4582
–4588
(2006
).10.
B. E.
Gilchrist
, S. G.
Ohler
, and A. D.
Gallimore
, “Flexible microwave system to measure the electron number density and quantify the communications impact of electric thruster plasma plumes
,” Rev. Sci. Instrum.
68
, 1189
–1194
(1997
).11.
K. E.
Harwell
and R. G.
Jahn
, “Initial ionization rates in shock-heated argon, krypton and xenon
,” Phys. Fluids
7
, 214
–222
(1964
).12.
A. J.
Kelly
, “Atom-atom ionization cross sections of the noble gases–argon, krypton, and xenon
,” J. Chem. Phys.
45
, 1723
–1732
(1966
).13.
T. I.
McLaren
and R. M.
Hobson
, “Initial ionization rates and collision cross section in shock-heated argon
,” Phys. Fluids
11
, 2162
–2171
(1968
).14.
K.-P.
Schneider
and C.
Park
, “Shock tube study of ionization rates of NaCl-contaminated argon
,” Phys. Fluids
18
, 969
–981
(1975
).15.
Y. K.
Karasevich
, “Kinetics of chemical ionization in shock waves: Ionization kinetics in hydrocarbon oxidation
,” Kinet. Catal.
49
, 610
–615
(2008
).16.
Y. K.
Karasevich
, “Kinetics of chemical ionization in shock waves: Kinetic model of ionization in methane oxidation
,” Kinet. Catal.
50
, 73
–81
(2009
).17.
Y. K.
Karasevich
, “Kinetics of chemical ionization in shock waves: IV. Kinetic model of ionization in acetylene oxidation
,” Kinet. Catal.
50
, 617
–626
(2009
).18.
P. A.
Vlasov
, I. V.
Zhiltsova
, V. N.
Smirnov
, A. M.
Tereza
, G. L.
Agafonov
, and D. I.
Mikhailov
, “Chemical ionization of n-hexane, acetylene, and methane behind reflected shock waves
,” Combust. Sci. Technol.
190
, 57
–81
(2018
).19.
See http://www.millitech.com for Millitech, Inc.; accessed
December 2018
.20.
A.
Alquaity
, E.
Es-sebbar
, and A.
Farooq
, “Sensitive and ultra-fast species detection using pulsed cavity ringdown spectroscopy
,” Opt. Express
23
, 7217
(2015
).21.
A. B. S.
Alquaity
, “Laser and mass spectrometric measurements of combustion species
,” Ph.D. thesis, King Abdullah University of Science and Technology
, Thuwal, Kingdom of Saudi Arabia
, 2016
.22.
S. W.
Janson
, “Microwave diagnostics for ion engines
,” in 23rd International Electric Propulsion Conference Seattle, WA, IEPC-93-237
(AIAA
, 1993
), pp. 2185
–2189
.23.
F. E.
Coffield
, S. R.
Thomas
, D.
Lang
, and R. D.
Stever
, “Microwave interferometer using 94-GHz solid-state sources
,” in 10th IEEE Symposium on Fusion Engineering
(IEEE
, 1983
).24.
G. D.
Reed
, W. A.
Hargus
, Jr., and M. A.
Cappelli
, “Microwave interferometry (90 GHz) for hall thruster plume density characterization
,” in AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Tuscon, AZ
(AIAA
, 2005
).25.
A.
Singh
, X.
Gao
, E.
Yavari
, M.
Zakrzewski
, X. H.
Cao
, V. M.
Lubecke
, and O.
Boric-Lubecke
, “Data-based quadrature imbalance compensation for a CW Doppler radar system
,” IEEE Trans. Microwave Theory Tech.
61
, 1718
–1724
(2013
).26.
B.-K.
Park
, S.
Yamada
, and V.
Lubecke
, “Measurement method for imbalance factors in direct-conversion quadrature radar system
,” IEEE Microwave Wireless Compon. Lett.
17
, 403
–405
(2007
).27.
F. F.
Chen
, Plasma Physics and Controlled Fusion, Vol. 1: Plasma Physics
(Plenum Press
, New York and London
, 1984
).28.
M.
Ghorannevisse
and M.
Avakian
, “Interferometry measurement of line average electron density in Alvand IIC tokamak
,” Int. J. Infrared Millimeter Waves
14
, 17
–22
(1993
).29.
30.
K.
Dittmann
, C.
Kullig
, and J.
Meichsner
, “160 GHz Gaussian beam microwave interferometry in low-density RF plasmas
,” Plasma Sources Sci. Technol.
21
, 024001
(2012
).31.
O.
Tudisco
, A. L.
Fabris
, C.
Falcetta
, L.
Accatino
, R. D.
Angelis
, M.
Manente
, F.
Ferri
, M.
Florean
, C.
Neri
, C.
Mazzota
, D.
Pavarin
, F.
Pollastrone
, G.
Rocchi
, A.
Selmo
, L.
Tasinato
, F.
Trezzolani
, and A. A.
Tuccillo
, “A microwave interferometer for small and tenuous plasma density measurements
,” Rev. Sci. Instrum.
84
, 033505
(2013
).32.
33.
J.
Elizondo
, D.
Korneev
, I.
Nascimento
, and W.
de Sa
, “TCABR interferometer
,” Braz. J. Phys.
32
, 123
–130
(2002
).34.
See http://www.rexolite.com for Rexolite; accessed
December 2018
.35.
S.
Trabelsi
, A. W.
Kraszewski
, and S. O.
Nelson
, “Phase-shift ambiguity in microwave dielectric properties measurements
,” IEEE Trans. Instrum. Meas.
49
, 56
–60
(2000
).36.
G.
Neumann
, U.
Banziger
, M.
Kammeyer
, and M.
Lange
, “Plasma-density measurements by microwave interferometry and Langmuir probes in an RF discharge
,” Rev. Sci. Instrum.
64
, 19
–25
(1993
).37.
D. C.
Murphy
, “The measurement and application of electric effects in combustion
,” Ph.D. thesis, University of California
, Berkeley
, 2015
.38.
D. F.
Davidson
and R. K.
Hanson
, “Interpreting shock tube ignition data
,” in WSSCI Fall 2003 Meeting
, 2003
.39.
A. B.
Alquaity
, C.
Bingjie
, J.
Han
, H.
Selim
, M.
Belhi
, Y.
Karakaya
, T.
Kasper
, S. M.
Sarathy
, F.
Bisetti
, and A.
Farooq
, “New insights into methane-oxygen ion chemistry
,” Proc. Combust. Inst.
36
, 1213
–1221
(2017
).40.
W. K.
Metcalfe
, S. M.
Burke
, S. S.
Ahmed
, and H. J.
Curran
, “A hierarchical and comparative kinetic modeling study of C1−C2 hydrocarbon and oxygenated fuels
,” Int. J. Chem. Kinet.
45
, 638
–675
(2013
).41.
J.
Prager
, U.
Riedel
, and J.
Warnatz
, “Modeling ion chemistry and charged species diffusion in lean methane-oxygen flames
,” Proc. Combust. Inst.
31
, 1129
–1137
(2007
).© 2019 Author(s).
2019
Author(s)
You do not currently have access to this content.
