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gas mixtures dielectric barrier discharge

Posted Mar 29, 2015, 7:22 p.m. EDT Plasma Physics Version 4.3 5 Replies

Ayoub Zouaghi
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Hi everyone,
I am working on DBD model in N2-He gas mixtures using Plasma DC Discharge module. For exemple if I take a mixture of 40%N2 with 60%He , how can I specify the quantity or the percentage of N2 and He in the mixture ?

Looking forward to hear from you
Thank you (*_*)
5 Replies Last Post Mar 31, 2015, 8:05 a.m. EDT
Luke Gritter Certified Consultant
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Posted: 10 years ago Mar 30, 2015, 9:41 a.m. EDT
Ayoub,

Once you have added in your plasma chemistry containing all the species you want to include in the simulation, you have to set the initial mole fraction of each species. This is done on the settings tab for each "Species" node (e.g. "Species: N2") in the Model Builder. If you left-click on the "Species" node and scroll down to the bottom of the Settings for that node, you will see the "Initial mole fraction" entry box. You can enter 0.4 for N2, small values for all excited species, and set He to calculate the initial mole fraction from the mass constraint by checking the "From mass constraint" box in the "Species Formula" section of the settings for this species.

--
Luke Gritter
AltaSim Technologies
Ayoub, Once you have added in your plasma chemistry containing all the species you want to include in the simulation, you have to set the initial mole fraction of each species. This is done on the settings tab for each "Species" node (e.g. "Species: N2") in the Model Builder. If you left-click on the "Species" node and scroll down to the bottom of the Settings for that node, you will see the "Initial mole fraction" entry box. You can enter 0.4 for N2, small values for all excited species, and set He to calculate the initial mole fraction from the mass constraint by checking the "From mass constraint" box in the "Species Formula" section of the settings for this species. -- Luke Gritter AltaSim Technologies
Ayoub Zouaghi
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Posted: 10 years ago Mar 30, 2015, 2:40 p.m. EDT
Hi Luck,
Thank you so much for your help, I am gratefull. I have another question please:
to let the initial number of positif ions be the same as the initial number of electrons, we select the "Initial value from electroneutrality constraint" check box.

*In my case I have two kind of positif ions (N2+ and He+), how can I let the plasma initially neutral in this case ?

*same question if we have both positif and negatif ions and electrons (ex: N2+ , O2+ , O-) ?

please I need your help
thank you
Hi Luck, Thank you so much for your help, I am gratefull. I have another question please: to let the initial number of positif ions be the same as the initial number of electrons, we select the "Initial value from electroneutrality constraint" check box. *In my case I have two kind of positif ions (N2+ and He+), how can I let the plasma initially neutral in this case ? *same question if we have both positif and negatif ions and electrons (ex: N2+ , O2+ , O-) ? please I need your help thank you
Luke Gritter Certified Consultant
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Posted: 10 years ago Mar 30, 2015, 5:24 p.m. EDT
Ayoub,

For electrons, the initial number density is set on the Initial Values node. For ions, the initial number density is set on the appropriate Species node (at the bottom of the "General Parameters" section). You can simply enter the initial number density of electrons and each ion species so that the charge adds up to zero. If you want to use the option "Initial value from electroneutrality constraint", you can activate it for only one of the ions. In this case, make sure you have entered the other initial values of charged species in appropriate quantities such that the software calculates a positive initial number density for this species.

--
Luke Gritter
AltaSim Technologies
Ayoub, For electrons, the initial number density is set on the Initial Values node. For ions, the initial number density is set on the appropriate Species node (at the bottom of the "General Parameters" section). You can simply enter the initial number density of electrons and each ion species so that the charge adds up to zero. If you want to use the option "Initial value from electroneutrality constraint", you can activate it for only one of the ions. In this case, make sure you have entered the other initial values of charged species in appropriate quantities such that the software calculates a positive initial number density for this species. -- Luke Gritter AltaSim Technologies
Ayoub Zouaghi
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Posted: 10 years ago Mar 30, 2015, 6:20 p.m. EDT
Thank you Luke I appreciate your help.
To clarify, lets suppose that we have those charged species: electrons, O-, O2+, N2+.
To let the plasma globally neutral, the sum of electrons and O- initial numbers should be equal to the sum of N2+ and O2+ initial number densities, is that correct ? no need to use "Initial value from electroneutrality constraint" . am I right?
Thank you Luke I appreciate your help. To clarify, lets suppose that we have those charged species: electrons, O-, O2+, N2+. To let the plasma globally neutral, the sum of electrons and O- initial numbers should be equal to the sum of N2+ and O2+ initial number densities, is that correct ? no need to use "Initial value from electroneutrality constraint" . am I right?
Luke Gritter Certified Consultant
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Posted: 10 years ago Mar 31, 2015, 8:05 a.m. EDT
Correct.

--
Luke Gritter
AltaSim Technologies
Correct. -- Luke Gritter AltaSim Technologies

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