COMSOL 6.4 - Dielectric Barrier Discharge in Air

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Dielectric Barrier Discharge in Air

Dielectric barrier discharge (DBD) is a non-thermal plasma phenomenon that occurs between two electrodes separated by a dielectric layer. It is widely employed in applications such as ozone generation, surface modification, and plasma medicine. The presence of the dielectric barrier significantly influences the discharge process by altering the electric field distribution and controlling the motion of charged species. In particular, the accumulation and relaxation of surface charges at the dielectric interface play a crucial role in determining discharge dynamics.

This model simulates DBD in air under an applied AC voltage. As the voltage amplitude increases, the discharge becomes more intense, and the dominant contribution to the total current shifts from displacement current to conduction current.

Model Definition

The Electric Discharge interface is used to simulate the DBD. The built-in charge transport model is used:

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e, p, n denote electrons, positive ions, and negative ions

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ni is the number density of the charge carrier (SI unit: 1/m3)

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E is the electric field (SI unit: V/m)

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zi denotes the carrier charge (SI unit: 1)

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μi denotes the carrier mobility (SI unit: m2/(V·s))

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wi is the drift velocity in the electric field (SI unit: m/s)

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Di is the diffusion coefficient (SI unit: m2/s)

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Ri is the reaction rate (SI unit: 1/(m3·s))

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α is the ionization coefficient (SI unit: 1/m)

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η is the attachment coefficient (SI unit: 1/m)

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βep is the electron–ion recombination coefficient (SI unit: m3/s)

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βpn is the ion–ion recombination coefficient (SI unit: m3/s)

The above transport equations are fully coupled with Poisson’s equation through the electric field and the space charge:

where e is the elementary charge.

The Gas–Solid interface is modeled with the dedicated Dielectric Interface, Surface Transport feature described in the Electric Discharge Module User’s Guide.

Results and Discussion

Figure 1 shows the discharge current as a function of time from the first study. The total current consists of the displacement current superimposed with the gas discharge current. Figure 2 shows the surface charge density at the inner and outer surfaces as a function of time.

Figure 1: The discharge current as a function of time.

Figure 2: The radial distributions surface charge density at several time instants of the first study.

Electric_Discharge_Module/Dielectric_Barrier_Discharges/dbd

Modeling Instructions

From the menu, choose .

In the window, click

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In the window, click

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In the tree, select > .

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In the tree, select > .

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In the window, under click .

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In the window for , locate the section.

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From the list, choose .

Global Definitions

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In the window, under click .

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In the window for , locate the section.

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In the table, enter the following settings:


Name	Expression	Value	Description
Vp	1[kV]	1000 V
f	50[Hz]	50 Hz
t	1/f/100	2E-4 s
Va	Vpsin(2pift)	62.791 V

Interval 1 (i1)

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In the window, under right-click and choose .

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In the window for , locate the section.

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In the table, enter the following settings:


Coordinates (cm)
0.1
0.2
1
1.1

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Electric Discharge (edis)

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In the window, under click .

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In the window for , locate the section.

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Select the checkbox.

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In the window, under > click .

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Select Domains 1 and 3 only.

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In the window for , locate the section.

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From the list, choose .

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Locate the section. From the εr list, choose . In the associated text field, type 3.5.

Add Material from Library

In the toolbar, click

and choose .

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Go to the window.

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In the tree, select > > > .

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Right-click and choose .

Air [Morrow and Lowke, 1997] (mat1)

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In the window, under > click .

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In the window for , locate the section.

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In the list, choose and .

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Select Domain 2 only.

Electric Discharge (edis)

In the window, under > click .

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In the toolbar, click

and choose .

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Select Boundary 1 only.

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In the window for , locate the section.

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In the V0 text field, type Va.

In the window, click .

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In the toolbar, click

and choose .

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Select Boundary 4 only.

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In the window, under click .

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In the window for , locate the section.

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From the list, choose .

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In the window, right-click and choose .

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Select Domain 2 only.

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In the window for , locate the section.

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From the list, choose .

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In the text field, type 200.

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In the text field, type 5.

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Select the checkbox.

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Right-click and choose .

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Select Domains 1 and 3 only.

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In the window for , locate the section.

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In the text field, type 10.

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Step 2: Time Dependent

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In the window, under click .

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In the window for , locate the section.

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In the text field, type range(1/f/100,1/f/20,2/f).

Global Variable Probe 1 (var1)

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In the toolbar, click

and choose .

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In the window for , locate the section.

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In the text field, type edis.I0_0.

Parametric Sweep

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In the toolbar, click

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In the window for , locate the section.

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In the table, enter the following settings:


Parameter name	Parameter value list	Parameter unit
Vp	1 10 20	kV

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In the window, click .

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In the window for , locate the section.

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Clear the checkbox.

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In the toolbar, click

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In the window, right-click and choose .

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In the window for , locate the section.

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From the list, choose .

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From the list, choose .

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Locate the section. In the table, enter the following settings:


Expression	Unit	Description
edis.V0_0	kV	Terminal voltage

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Locate the section. From the list, choose .

Probe Plot Group 1

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In the window, click .

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In the window for , locate the section.

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Select the checkbox.

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Select the checkbox. In the associated text field, type Current, A.

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Select the checkbox. In the associated text field, type Voltage, kV.

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In the table, select the checkbox for .

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Locate the section. From the list, choose .

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Click to expand the section. From the list, choose .

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In the toolbar, click

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Surface Charge Density

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In the toolbar, click

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In the window for , type Surface Charge Density in the text field.

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Right-click and choose .

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Select Boundaries 2 and 3 only.

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In the window for , locate the section.

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In the text field, type edis.rhos.

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In the field, type nC/mm^2.

In the window, under > right-click and choose .

In the window, right-click and choose .

Surface Charge Density

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In the window for , locate the section.

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From the list, choose .

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Locate the section. Select the checkbox.

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Select the checkbox. In the associated text field, type Surface charge density, nC/mm<sup>2</sup>.

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Select the checkbox.

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In the window, click .

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In the window for , click to expand the section.

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Select the checkbox.

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From the list, choose .

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In the table, enter the following settings:


Legends
Inner surface
Outer surface

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Click to expand the section. Find the subsection. From the list, choose .

Surface Charge Density

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In the window, click .

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In the window for , locate the section.

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From the list, choose .

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In the toolbar, click

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