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Plasma reaction rate units?
Posted Sep 18, 2014, 9:44 p.m. EDT Plasma Physics Version 4.4 1 Reply
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Hello,
in www.comsol.com/community/forums/general/thread/42059/
about cross sections in the plasma module
I got lost in the units of the rate coefficients..
In the manual/help/nomenclature I found:
rj Reaction rate, reaction j [mol/(m^3*s)]
kj Rate coefficient, reaction j [m^3/(mol*s)]
Rk Rate expression, species k [kg/(m^3*s)]
then for the source coefficients:
In the case of rate coefficients, the electron source term is given by
Re=Sum(xj*kj*Nn*ne)
where xj is the mole fraction of the target species for reaction j, kj is the rate coefficient
for reaction j (SI unit: [m^3/s]) and Nn is the total neutral number density (SI unit: [1/m^3]).
(ne electron number density [1/m^3] , i believe)
Here the kj has two different units ? [m^3/(mol*s)] or [m^3/s]
How do I connect the [kg] and [mol] into this unit conversion?
Arigatou gosaimasu
Lukas
nagoya-u
in www.comsol.com/community/forums/general/thread/42059/
about cross sections in the plasma module
I got lost in the units of the rate coefficients..
If you are also loading rate coefficients from the COMSOL Boltzmann solver, beware of the units. Last I checked, the MWP interface expects rate coefficients in m^3/(mol*s) while the Boltzmann solver outputs rate coefficients in m^3/s, so be sure to do the conversion.
--
Luke Gritter
AltaSim Technologies
In the manual/help/nomenclature I found:
rj Reaction rate, reaction j [mol/(m^3*s)]
kj Rate coefficient, reaction j [m^3/(mol*s)]
Rk Rate expression, species k [kg/(m^3*s)]
then for the source coefficients:
In the case of rate coefficients, the electron source term is given by
Re=Sum(xj*kj*Nn*ne)
where xj is the mole fraction of the target species for reaction j, kj is the rate coefficient
for reaction j (SI unit: [m^3/s]) and Nn is the total neutral number density (SI unit: [1/m^3]).
(ne electron number density [1/m^3] , i believe)
Here the kj has two different units ? [m^3/(mol*s)] or [m^3/s]
How do I connect the [kg] and [mol] into this unit conversion?
Arigatou gosaimasu
Lukas
nagoya-u
1 Reply Last Post Sep 19, 2014, 3:45 p.m. EDT
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Posted:
1 decade ago
Lukas,
To convert from [m^3/s] to [m^3/(mol*s)], simply multiply the first by the Avogadro constant (N_A_const in COMSOL).
If you export the rate coefficients for the electron impact reactions from the Boltzmann solver, you should multiply these values by the Avogadro constant before loading them into the Microwave Plasma interface.
--
Luke Gritter
AltaSim Technologies
To convert from [m^3/s] to [m^3/(mol*s)], simply multiply the first by the Avogadro constant (N_A_const in COMSOL).
If you export the rate coefficients for the electron impact reactions from the Boltzmann solver, you should multiply these values by the Avogadro constant before loading them into the Microwave Plasma interface.
--
Luke Gritter
AltaSim Technologies