Modeling Atmospheric-Pressure Plasma and Plasma Chemistry (Fa-Gung Fan and Santokh Badesha)

Modeling Atmospheric-Pressure
Plasma and Plasma Chemistry

Fa-Gung Fan* and Santokh S. Badesha
Xerox Corporation
5/21/2010

* http://www.linkedin.com/in/fagungfan

Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010

Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010

Outline

DC Coaxial Wire-Cylinder Corona
DC Needle-Plate Corona
Coplanar Dielectric Barrier Discharge (DBD)
– Streamer
RF Plasma Needle (Plasma-induced Chemistry)


Positive and Negative
DC Wire-Cylinder Corona


Positive DC Wire-Cylinder Corona
Photoemission,
Secondary emission

Wire radius: 100 microns
Photoionization
Cylinder radius: 5 mm

Positive ion
wire
surface
Photoemission, Number Density
Secondary emission

Ionization Electron
Model domain and Ground boundary
(E/N=120Td)
computational mesh
3500V
(at wire
surface)
Negative ion

(m)
r
cylinder wall


Number Density in Ionization Region

Present work Chen and Davidson, Plasma Chem. Plasma
Positive ion Process., 22, pp. 199-224, (2002)

Negative ion

Electron

r (m) r (micron)

wire Ionization wire
surface boundary surface
(E/N=120Td)

Note: The two are similar cases, but not identical.
(The model domain and the boundary conditions are different.)


Negative DC Wire-Cylinder Corona
Plasma
boundary
(E/N=80Td)

Negative ion

Model domain and Ground

computational mesh
Electron
-3000V
(at wire
Ionization
surface)
boundary
(E/N=120Td)

Positive ion

wire
surface


Number Density in Ionization Region

Present work Chen and Davidson, Plasma Chem. Plasma
Process., 23(1), pp. 83-102, (2003)

Positive ion
Negative ion

Electron

r
wire Ionization wire
surface boundary surface
(E/N=120Td)

Note: The two are similar cases, but not identical.
(The model domain and the boundary conditions are different.)


Positive and Negative


Positive DC Needle-Plate Corona (Axisymmetric model)
Plate
(grounded)

Axis of Electric Field Magnitude (surface)
symmetry
Electric Field (arrows)
Electrical Potential (contour lines)

Needle
(900V)

Positive Ion Density (surface)
Positive Ion Flux (arrows)


Electron Density and Ionization Boundary

Ionization
boundary
(E/N=120Td)


Negative DC Needle-Plate Corona (Axisymmetric model)
Plate
(grounded)

Axis of
symmetry
Electron Density (surface)
Electron Flux (arrows)
Needle
(-900V)

Negative Ion Density (surface)
Negative Ion Flux (arrows)


Electron Density, Ionization Boundary, and Plasma Boundary

Plasma
boundary
(80Td)

Ionization
boundary
(120Td)


Number Density of Charge Species
(Negative DC Needle-Plate Corona)

Only the ionization region
Ionization
boundary
(120Td)

Negative ion
Positive ion

Negative ion

Electron
Plasma
boundary
(80Td)

Positive ion Electron

(m) (m)
z z Ionization
Needle boundary
Needle
tip
tip (120Td)


Negative Charge Density Profile Charging Profile
at the Plate (Negative Charge Flux at the Plate)

Negative ion
Electron

Negative ion
Electron

(m) (m)

r r
Axis of Axis of
symmetry symmetry


Streamer in
Coplanar Dielectric-Barrier-
Discharge (DBD) Corona
Ref: Gibalov and Pietsch, J. Phys. D: Appl. Phys.,
37, pp. 2082–2092 (2004)


Air

electrode electrode

Dielectric

Electrode Configuration in a Coplanar DBD
(2D Model)


Electron Density on the Dielectric Electrical Potential at the Dielectric
Surface at Different Time Surface at Different Time
t (sec)
t (sec)

As the streamer propagating toward the cathode, the electrons generated
by the ionization deposit on the dielectric surface at the location just
above the anode (left figure). This charge build-up modifies the surface
potential of the dielectric (right figure).
The ions move slow, and the effect can be neglected in the time frame
simulated.

RF Plasma Needle and
Plasma-induced Chemistry
Ref: Sakiyama and Graves, J. Phys. D: Appl. Phys.,
39(16), pp. 3644-3652 (2006)


Plasma Needle for Medical Application

13.56MHz

Brok et al., J. Appl. Phys., 98, p. 013302 (2005)


Brok et al., J. Appl. Phys., 98, p. 013302 (2005)


Summary

DC Coaxial Wire-Cylinder Corona
Coplanar Dielectric Barrier Discharge (DBD)
– Streamer
RF Plasma Needle in He-N2 Mixture


Modeling Atmospheric-Pressure Plasma and Plasma Chemistry (Fa-Gung Fan and Santokh Badesha)

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