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Plasma Module Error: Failed to Evaluate Variable Jacobian

Posted 3 dic 2013, 15:35 GMT-5 Plasma Physics 2 Replies

Michael Muchemu
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I am attempting to model a DC microdischarge in Argon using COMSOL 4.2. I am using a 2D axisymmetric model. The top layer is the anode, the middle layer is a dielectric and the bottom layer is the cathode. The small triangular section is the micro-cavity. The rest is the 'chamber', consisting of Ar.

I've imported all the necessary cross sections as well as townsend coefficients from another physics interface. I have defined my materials properly (resistivity data on the anode and cathode, and permittivity data on the argon).

I've checked and re-checked my BC's and my materials, but despite it all I can't figure out why I get:

Failed to evaluate variable Jacobian:

- Variable : mod1.dc.sfluxi_wAr_1p
- Geometry: 1
- Boundary: 14

I understand the Ar_1p is COMSOL's notation for Ar+. However, I can't locate the variable 'sfluxi_wAr_1p'. The boundary number refers the anode region contiguous to the microcavity.

I've attached my model.

Any help will be greatly appreciated.

Attachments:

2 Replies Last Post 3 dic 2013, 18:43 GMT-5
Luke Gritter Certified Consultant
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Posted: 1 decade ago 3 dic 2013, 17:00 GMT-5
Michael,

Everywhere you specify a Wall boundary condition, you also need to specify a surface reaction boundary condition for each heavy species (in your case, for Ars and Ar+).

--
Luke Gritter
AltaSim Technologies
Michael, Everywhere you specify a Wall boundary condition, you also need to specify a surface reaction boundary condition for each heavy species (in your case, for Ars and Ar+). -- Luke Gritter AltaSim Technologies
Michael Muchemu
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Posted: 1 decade ago 3 dic 2013, 18:43 GMT-5

Michael,

Everywhere you specify a Wall boundary condition, you also need to specify a surface reaction boundary condition for each heavy species (in your case, for Ars and Ar+).

--
Luke Gritter
AltaSim Technologies


Thanks for the quick reply.

I didn't know that.

It was definitely the problem, since it runs without errors now. But I have to disable the External Surface Charge Accumulation BC (ESCABC).

When I enable this BC, it shows the Jacobian error, for the variable nJe on the boundary 12 (that's the dielectric boundary, precisely where the ESCABC is defined). I am not meant to specify anything for this beyond the required boundary, am I?




[QUOTE] Michael, Everywhere you specify a Wall boundary condition, you also need to specify a surface reaction boundary condition for each heavy species (in your case, for Ars and Ar+). -- Luke Gritter AltaSim Technologies [/QUOTE] Thanks for the quick reply. I didn't know that. It was definitely the problem, since it runs without errors now. But I have to disable the External Surface Charge Accumulation BC (ESCABC). When I enable this BC, it shows the Jacobian error, for the variable nJe on the boundary 12 (that's the dielectric boundary, precisely where the ESCABC is defined). I am not meant to specify anything for this beyond the required boundary, am I?

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