4. Positive and Negative
DC Wire-Cylinder Corona
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
5. 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
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
6. 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.)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
7. 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
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
8. 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.)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
9. Positive and Negative
DC Needle-Plate Corona
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
10. 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)
Electrical Potential (contour lines)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
11. Electron Density and Ionization Boundary
Ionization
boundary
(E/N=120Td)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
12. Negative DC Needle-Plate Corona (Axisymmetric model)
Plate
(grounded)
Axis of
symmetry
Electron Density (surface)
Electron Flux (arrows)
Electrical Potential (contour lines)
Needle
(-900V)
Negative Ion Density (surface)
Negative Ion Flux (arrows)
Electrical Potential (contour lines)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
13. Electron Density, Ionization Boundary, and Plasma Boundary
Plasma
boundary
(80Td)
Ionization
boundary
(120Td)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
14. 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)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
15. 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
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
16. Streamer in
Coplanar Dielectric-Barrier-
Discharge (DBD) Corona
Ref: Gibalov and Pietsch, J. Phys. D: Appl. Phys.,
37, pp. 2082–2092 (2004)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
17. Air
electrode electrode
Dielectric
Electrode Configuration in a Coplanar DBD
(2D Model)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
19. 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.
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
20. RF Plasma Needle and
Plasma-induced Chemistry
Ref: Sakiyama and Graves, J. Phys. D: Appl. Phys.,
39(16), pp. 3644-3652 (2006)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
21. Plasma Needle for Medical Application
13.56MHz
Brok et al., J. Appl. Phys., 98, p. 013302 (2005)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
22. Brok et al., J. Appl. Phys., 98, p. 013302 (2005)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010
23. Brok et al., J. Appl. Phys., 98, p. 013302 (2005)
Fa-Gung Fan Annual CAMP Technical Meeting, Canandaigua, NY, 5/19-21, 2010