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parallel strip capacitors with small current injection
Posted Dec 1, 2015, 3:07 a.m. EST 2 Replies
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Dear All,
I have a 3D geometry for a simulation of a capacitive tool, made of thin parallel metal strips. I have laid out parallel thin metal strip layers in space, with some insulator in between. I have managed at least to follow an Electrostatic tutorial from the Application Library so that I can apply a constant bias voltage (~500 V) on the electrodes.
But now, I would like to apply a small pulsed current (100 nA, lasting 100 ns) onto one of my strips and see they would capacitively couple the small current onto the other strips, on the other terminal end of my capacitive device. So I would like to simulate this injection of small current, and extract from the simulation the induced conductive current on the other metal strips.
My problem is:
1) How can I apply such a very small pulsed current on one of my Terminals? Perhaps there is some example/tutorial already for this?
2) How can I extract the induced current from the other Terminal strips?
3) How can I set the resistivity of my strips?
Thank you for help
Balint
I have a 3D geometry for a simulation of a capacitive tool, made of thin parallel metal strips. I have laid out parallel thin metal strip layers in space, with some insulator in between. I have managed at least to follow an Electrostatic tutorial from the Application Library so that I can apply a constant bias voltage (~500 V) on the electrodes.
But now, I would like to apply a small pulsed current (100 nA, lasting 100 ns) onto one of my strips and see they would capacitively couple the small current onto the other strips, on the other terminal end of my capacitive device. So I would like to simulate this injection of small current, and extract from the simulation the induced conductive current on the other metal strips.
My problem is:
1) How can I apply such a very small pulsed current on one of my Terminals? Perhaps there is some example/tutorial already for this?
2) How can I extract the induced current from the other Terminal strips?
3) How can I set the resistivity of my strips?
Thank you for help
Balint
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2 Replies Last Post Dec 6, 2015, 5:46 p.m. EST
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Posted:
9 years ago
This question was answered in a regular COMSOL Support case.
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Posted:
9 years ago
Hi Sven,
As you probably read the thread on Friday, thanks to you I managed to get it going with 5.2
(after some phone calls CERN IT kindly helped and provided the 5.2 license).
I can recover the capacitive coupling nicely on both middle and bottom strip layers one I apply
the pulse on the top resistive layer. Really nice, thanks a lot.
However, I would like to ask a perhaps trivial question. I have increased the number of strips, and transformed all the non-resistive strips and resistive strips to "Terminals" because I wanted to be able to measure the "Terminal current" on each of them. I put the V0 to V0 = 0 volt (ground) for the grounded strips and I apply some resistive strips the usual Gaussian pulse.
Then when I plot the current from the defined surface boundary (ec.Jx or ec.Jy depending on what the orientation of the end of the strips are) I get around ~1e-02 nA currents on the strips or smaller current. But when I plot the "Terminal current", ec.I0_1 (or similar) for the same strips (or Terminals) I get roughly ~100 nA. Could you let me know why is this like this?
A related feature is that if I ask for the ec.Jx or ec.Jy currents I get that this current is larger on the bottom layer strips than on the middle layer strips. While if I ask for the corresponding ec.I0_1 (or similar) corresponding "Terminal currents" on the same strips this kind of current is larger on the middle strips than on the bottom strips. So, it seems to show opposite behaviour.
So, there must be some kind of underlying definition which is not obvious to me. I am guessing that the "Terminal current" is the integral of the total current density over the volume of the geometrical object, while the ec.Jx things are just the current across the surface ?
(At least qualitatively the "Terminal current" behaviour is more consistent with what the data shows: the measured pulse heights are larger on the middle strips than on the bottom strips. Because we would like to understand exactly this behaviour in the detector I am trying to understand which kind of definition of current is more useful in practice.)
Thanks a lot for help.
Balint
As you probably read the thread on Friday, thanks to you I managed to get it going with 5.2
(after some phone calls CERN IT kindly helped and provided the 5.2 license).
I can recover the capacitive coupling nicely on both middle and bottom strip layers one I apply
the pulse on the top resistive layer. Really nice, thanks a lot.
However, I would like to ask a perhaps trivial question. I have increased the number of strips, and transformed all the non-resistive strips and resistive strips to "Terminals" because I wanted to be able to measure the "Terminal current" on each of them. I put the V0 to V0 = 0 volt (ground) for the grounded strips and I apply some resistive strips the usual Gaussian pulse.
Then when I plot the current from the defined surface boundary (ec.Jx or ec.Jy depending on what the orientation of the end of the strips are) I get around ~1e-02 nA currents on the strips or smaller current. But when I plot the "Terminal current", ec.I0_1 (or similar) for the same strips (or Terminals) I get roughly ~100 nA. Could you let me know why is this like this?
A related feature is that if I ask for the ec.Jx or ec.Jy currents I get that this current is larger on the bottom layer strips than on the middle layer strips. While if I ask for the corresponding ec.I0_1 (or similar) corresponding "Terminal currents" on the same strips this kind of current is larger on the middle strips than on the bottom strips. So, it seems to show opposite behaviour.
So, there must be some kind of underlying definition which is not obvious to me. I am guessing that the "Terminal current" is the integral of the total current density over the volume of the geometrical object, while the ec.Jx things are just the current across the surface ?
(At least qualitatively the "Terminal current" behaviour is more consistent with what the data shows: the measured pulse heights are larger on the middle strips than on the bottom strips. Because we would like to understand exactly this behaviour in the detector I am trying to understand which kind of definition of current is more useful in practice.)
Thanks a lot for help.
Balint
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