A SPECTROSCOPIC STUDY OF
DISCHARGE SPECIES PRODUCED IN
A PACKED BED DIELECTRIC
BARRIER DISCHARGE
Kenneth W. Engelinga, Maria C. Garciab, Juliusz
Kruszelnickia, Mark J. Kushnera, and John E. Fostera
[email protected], [email protected],
[email protected], [email protected], and
a)University of Michigan, Ann Arbor, MI, USAb)University of Cordoba, Cordoba, Spain
9th Annual MIPSE Graduate Symposium
*Work supported by the National Science Foundation and the DOE
Office of Fusion Energy Science
THE IMPORTANCE OF MICROPLASMAS
Spectroscopic Species and Packed Bed Reactors (PBRs)
• Non-thermal plasma production and propagation
• What are the reaction kinetic mechanisms?
• What surface properties enhance or limit plasma production in
microporous media?
• What variables are available to augment the plasma properties?
• Will the atmospheric plasma non-thermally interact with aggregate media?
Will they have non-destructive effects?
• How does surface morphology effect behavior and propagation (e.g.
catalysis, seeds)?
Micro-plasmas have the potential to advance chemical processing.
2
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
PACKED BED REACTOR DISCHARGES
• Introduction to PBRs
• Rod and mesh or film electrodes
• Dielectric aggregate of varying size, shape, and material
• Gas flow ports – feedstock gases, pollutants
• Various power sources (DC, AC, RF, pulsed)
• Applications
• Ozone generation
• Pollutant mitigation
• Dry-reforming of CH4
• Water reclamation
Seed as aggregate
Mesh ElectrodePlasma formation
3
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
DETAILED APPROACH
• To visualize plasma propagation in PBRs, a 2D cell
investigation was developed
• 2D minimizes overlapping plasmas components and
optical analysis vs. 3D
• Time-resolved optical emission spectroscopy analysis
with ICCD camera and spectrometer
• Monitor electron energetics
• Investigate modes for dielectric-to-dielectric
plasma propagation
• Structured and randomly placed aggregate
• Modeling
• nonPDPSIM, ANSYS:Maxwell EM solver
4
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
EFFECT OF DIELECTRICS
Dielectrics locally enhance the
electric field
Manipulation of media allows
for varying discharge
characteristics
Highest enhancement at
closest dielectric-dielectric
contact points
E/N scales with dielectric
constant
5 mm
ε/εo (26.6)
ε/εo (3.8)
5
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
2D EXPERIMENTAL SETUP
• Nanosecond, pulsed
discharge: 20 kV
• Gas Parameters
• Room air composition
• 760 Torr
• ICCD image capture
• 10 Hz, 100 Hz
• Pulse Delay Generator
Timing
• Zirconia• ε/εo = (26.6)
6
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
PREVIOUS EXPERIMENTAL FINDINGS
• Filamentary Microstreamers
(FM) to Surface Ionization
Waves (SIWs) to FMs as
plasma propagates in
different modes through PBR
• Discharges influenced by
strength of dielectric material
• Quartz and zirconia materials
studied
• Plasma localized at interstitial
locations and surfaces of
dielectric aggregate
7
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
Model, nonPDPSIM
Experiment
1 ms, integrated
OPTICAL EMISSION SPECTROSCOPY
8
• Provides insight into the plasma
• Species produced
• Plasma properties
300 400 500 600 700 800
0
10000
20000
30000
Cu I, Mo I
Zone 1
Second Order
N2+ (1st neg)
N2 (2nd pos)
Gate Delay = 74 ns
Gate Width = 10 ns
gates/Exp = 1000
Acc = 1
I (a
.u.)
(nm)
• Investigations focused on
N2 (337 nm) emission
• Pi-Max3 Acton Spectrometer
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
OPTICAL EMISSION SPECTROSCOPY
• Position (1)
• Placement between disks 1 and 2
• Data taken at 10 Hz, 100 Hz
• 4x Magnification of time-resolved imaging
• Tgas ≈ 345 K
9
0 20 40 60 80 100 120 140 160 180 200
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Position 1
N2 (337.1 nm)
10 Hz
100 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Position 1
N2 (337.1 nm)
10 Hz
100 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)
TIME-RESOLVED IMAGES: POSITION 1, 10 Hz
10
• 10 Hz
• 20 kV, 120 ns
pulse width
• 5 ns exposure
• 4x mag.
a) b) c) d)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Position 1
N2 (337.1 nm)
10 Hz
100 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)
TIME-RESOLVED IMAGES: POSITION 1, 100 Hz
11
• 100 Hz
• 20 kV, 120 ns
pulse width
• 5 ns exposure
• 4x mag.
a) b) c) d)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.00
0.02
0.04
0.06
0.08
0.10
0.12
POS 2 10 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)
OPTICAL EMISSION SPECTROSCOPY
• Position (2)
• Placement between disks 2 and 3
• Data taken at 10 Hz
• 4x Magnification of time-resolved imaging
• Tgas ≈ 345 K
12
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.00
0.02
0.04
0.06
0.08
0.10
0.12
POS 2 10 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)
• 10 Hz
• 20 kV, 120 ns
pulse width
• 5 ns exposure
• 4x mag.
13
TIME-RESOLVED IMAGES: POSITION 2, 10 Hz
a) b) c) d)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
POS 3
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
10 Hz
I (a
.u.)
Time Delay (ns)
OPTICAL EMISSION SPECTROSCOPY
• Position (3)
• Placement between disk 3 and planar electrode
• Data taken at 10 Hz
• 4x Magnification of time-resolved imaging
• Tgas ≈ 345 K
14
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
POS 3
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
10 Hz
I (a
.u.)
Time Delay (ns)
• 10 Hz
• 20 kV, 120 ns
pulse width
• 5 ns exposure
• 4x mag.
15
pla
nar e
lectro
de
a) b) c) d)
TIME-RESOLVED IMAGES: POSITION 3, 10 Hz
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
COMPARISON WITH MODEL
16
• Model (nonPDPSIM) predicts FM to SIW transition.
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
0 20 40 60 80 100 120 140 160 180 200
0.0
0.2
0.4
0.6
0.8
1.0
1.2 POS 1
POS 2
POS 3
10 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)0 50 100 150 200
0.0
0.2
0.4
0.6
0.8
1.0
Normalized at max
10 Hz
GWidth= 10 ns
GDelay changing
Gates/exp = 1000
Acc = 1
I (a
.u.)
Time Delay (ns)
POS1
POS2
POS3
SUMMARY OF EMISSION vs POSITIONS
17
a) b)
• Intensity increases as discharge propagates through
PBR
• Evidence of restrike (double maximum)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
12
3
45
67
t = 0-5 ns t = 5-10 ns t = 10-15
nst = 15-20
ns
t = 20-25 ns t = 25-30 ns t = 30-35 ns t = 35-40
ns
5 mm
EOverall E-field
Direction
1
2
3
4
5
6
7
6 mm
ZIRCONIA: DISCHARGE PROPAGATION
THROUGH PBR
18
• Explains time differences
in emission spectrum
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
CONCLUDING REMARKS
• Evidence of restrikes seen with N2
• Double maximum in emission spectra
• N2 (337.1 nm) peak emission intensity was dependent upon location for this geometry
• Emission peaks at each location at some point in time showing the plasma propagation through the cell
• Likely tracking the density of electrons with energy above the excitation threshold
• Future Investigations:
• Active interrogation to find atomic N populations
• Expand the N2 emission study
• Compare emission spectrum with that using materials of various dielectric strengths
19
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
QUESTIONS
20
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
ADDITIONAL SLIDES
19Topic
270 275 280 285 290 295 300
0
500
1000
1500
2000
2500
3000
293.65 Mo I
289.96 Cu I291.53 Mo I
280.57 Cu I
280.98 Cu I
281.27 Cu I
281.36 Cu I
276.26 Cu I
276.30 Mo I
Cu I
N2 (2nd pos) 297.68 nm
Gate Delay = 74 ns GWidth = 10 ns
Gates/exp = 1000
Acc: 1
I (a
.u.)
(nm)
300 320 340 360
0
5000
10000
15000
20000
25000
30000
35000
346.07 Mo I
348.16 Cu I
N2 (2nd pos) 333.90 nm
317.16 Cu I
317.56 Cu I
319.27 Mo I
322.34 Cu I
324.31 Cu I
and many others
308.25 Cu I
308.04 Mo I
309.39 Cu I
310.13 Mo I
N2 (2nd pos)
350.05 nm
353.67 nm
357.60 nmN2 (2nd pos) 311.67 nm, 313.60 nm, 315.93 nm
N2 (2nd pos) 337.13 nm
Gate Delay = 74 nsGWidth = 10 ns
Gates/exp = 1000
Acc: 1
I (a
.u.)
(nm)
360 380 400 420
0
1000
2000
3000
4000
5000
6000
7000
N2+ (1st neg)
385.79nm
391.44 nm
N2 (2nd pos)
394.30 nm,
399.84 nm,
405.94 nm
N2 (2nd pos)
394.30 nm, 399.84 nm,
405.94 nm
N2 (2nd pos)
371.05 nm, 375.54 nm, 380.49 nm
Mo I
Gate Delay = 74 ns GWidth = 10 ns
Gates/exp = 1000
Acc: 1
I (a
.u.)
(nm)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
ADDITIONAL SLIDES
19
0 50 100 150 200
280
300
320
340
360
380
400
10 Hz
POS 1
Tg
as (
K)
Time Delay (ns)
0 50 100 150 200
290
300
310
320
330
340
350
360POS 2
10 Hz
T
gas (
K)
Time Delay (ns)
20 40 60 80 100
280
300
320
340
360
380
400
420
10 Hz
POS 3
Tg
as (
K)
Time Delay (ns)
MIPSE_2018
University of Michigan
Institute for Plasma Science & Engr.
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