modeling atmospheric-pressure plasma and plasma chemistry (fa-gung fan and santokh badesha)

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

Modeling Atmospheric-Pressure Plasma and Plasma Chemistry

Fa-Gung Fan* and Santokh S. BadeshaXerox Corporation

5/21/2010

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

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)

Outline


Positive and Negative DC Wire-Cylinder Corona


Positive DC Wire-Cylinder Corona

r

Positive ion

Electron

Negative ion

3500V (at wire surface)

Ground

Number Density

Wire radius: 100 microns

Cylinder radius: 5 mm

cylinder wall

(m)

wire surface

Model domain and

computational mesh

Photoionization

Photoemission,

Secondary emission

Photoemission, Secondary emission

Ionization boundary

(E/N=120Td)


Chen and Davidson, Plasma Chem. Plasma

Process., 22, pp. 199-224, (2002)

Number Density in Ionization Region

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

Positive ion

Negative ion

Electron

(m) (micron)

wire surface

wire surface

r rIonization boundary

(E/N=120Td)

Present work


Negative DC Wire-Cylinder Corona

-3000V (at wire surface)

GroundModel domain and computational mesh

Positive ion

Electron

Negative ion

Ionization boundary

(E/N=120Td)

wire surface

Plasma boundary

(E/N=80Td)


Chen and Davidson, Plasma Chem. Plasma

Process., 23(1), pp. 83-102, (2003)

wire surface

r

Electron

Positive ion

Negative ion

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

Ionization boundary (E/N=120Td)

wire surface

Present work

Number Density in Ionization Region


Positive and Negative DC Needle-Plate Corona


Positive DC Needle-Plate Corona

Electric Field Magnitude (surface)

Electric Field (arrows)

Electrical Potential (contour lines)

Needle (900V)

Plate (grounded)

(Axisymmetric model)

Axis of

symmetry

Positive Ion Density (surface)

Positive Ion Flux (arrows)



Electron Density and Ionization Boundary

Ionization

boundary(E/N=120Td)


Negative DC Needle-Plate Corona

Electron Density (surface)

Electron Flux (arrows)


Needle (-900V)

Plate (grounded)

(Axisymmetric model)

Axis of symmetry

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

Negative ion

Positive ion

Electron

Electron

Positive ion

Negative ion

z zNeedle

tip

(m)

Needle tip

Ionization

boundary

(120Td)

(m)

Ionization boundary(120Td)

Plasma boundary

(80Td)


Negative Charge Density Profile

at the Plate

Charging Profile

(Negative Charge Flux at the Plate)

r r

Negative ion

Electron

Electron

Negative ion

Axis of symmetry

Axis of symmetry

(m) (m)


Streamer in Coplanar Dielectric-Barrier-Discharge (DBD) Corona

Ref: Gibalov and Pietsch, J. Phys. D: Appl. Phys.,

37, pp. 2082–2092 (2004)


electrode electrode

Dielectric

Air

Electrode Configuration in a Coplanar DBD

(2D Model)


Electron Density on the Dielectric

Surface at Different Time

Electrical Potential at the Dielectric

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 andPlasma-induced Chemistry

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


13.56MHz

Plasma Needle for Medical Application

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

� DC Needle-Plate 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)

Technology

wire surface negative

plasma chemistry fa

tdpositive ionwire surface

plasma process

secondary emission wire

plasmapositive ion process

boundary conditions

td computational mesh3500v