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electron density and ionisation degree in dc discharge
Posted 16 févr. 2017, 09:34 UTC−5 Plasma Physics Version 5.2 1 Reply
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Hi Dear All,
I want to simulate a cold plasma, generating by DC discharge.
I have seen the model of positif column, I remark that the electron density is 10^13 m-3, and neutral species density is 10^22 m -3
for example, if I want to calculate the ionisation degree, I should calculate this report: dc.ne/dc.Ne......and the result is in the order of 10^-9 .
for a cold plasma, the ionisation degree is in the order of 10-4
I would like to know if my formula is correct, and if it's the case, what I should be change to simulate a cold plasma, did I should change the electron density ?
also, I can't understanding how they are calculate the reduced electron mobility.
for another géométrie, the electron density and reduced mobilituy be must change ?
thank you in advance
I want to simulate a cold plasma, generating by DC discharge.
I have seen the model of positif column, I remark that the electron density is 10^13 m-3, and neutral species density is 10^22 m -3
for example, if I want to calculate the ionisation degree, I should calculate this report: dc.ne/dc.Ne......and the result is in the order of 10^-9 .
for a cold plasma, the ionisation degree is in the order of 10-4
I would like to know if my formula is correct, and if it's the case, what I should be change to simulate a cold plasma, did I should change the electron density ?
also, I can't understanding how they are calculate the reduced electron mobility.
for another géométrie, the electron density and reduced mobilituy be must change ?
thank you in advance
1 Reply Last Post 27 févr. 2017, 09:20 UTC−5
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Posted:
7 years ago
Hi,
In the model "positive_column_2d" the density of electrons is arround 1e16 m-3 and not (1e13 is the initial value).
The degree of ionization,alpha , is defined as alpha =ni/(ni+nn), where ni is the number density of ions and nn is the number density of neutral atoms. The electron density is related to this by the average charge state Z of the ions through ne =Z*ni, where ne is the number density of electrons.
Reduced electron mobility is not calculated in comsol plasma interface. you can introduce as constant or a table of mean electron energy vs reduced electron mobility
You can use the Boltzmann Equation physics interface in the Plasma Module to produce this table for your particular gas mixture and operating conditions. To learn how to use this interface, see the example models "boltzmann argon" and "boltzmann oxygen" in the COMSOL Model Library.
The reduced electron mobility is depend on gaz you used.
Good luck
In the model "positive_column_2d" the density of electrons is arround 1e16 m-3 and not (1e13 is the initial value).
The degree of ionization,alpha , is defined as alpha =ni/(ni+nn), where ni is the number density of ions and nn is the number density of neutral atoms. The electron density is related to this by the average charge state Z of the ions through ne =Z*ni, where ne is the number density of electrons.
Reduced electron mobility is not calculated in comsol plasma interface. you can introduce as constant or a table of mean electron energy vs reduced electron mobility
You can use the Boltzmann Equation physics interface in the Plasma Module to produce this table for your particular gas mixture and operating conditions. To learn how to use this interface, see the example models "boltzmann argon" and "boltzmann oxygen" in the COMSOL Model Library.
The reduced electron mobility is depend on gaz you used.
Good luck