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Modelling the interaction of alpha particle with a slab of material. Possible? Won't converge?
Posted 14 apr 2016, 06:02 GMT-4 Charged Particle Tracing, Heat Transfer & Phase Change, Studies & Solvers Version 5.2 1 Reply
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I'm currently running a 14 day trial of COMSOL and I'm trying to figure out whether it is able to simulate what I need to simulate.
To start with, I went for a simple model of a cylindrical slab of type 2a diamond with r=3.5mm and t=40 micron. I then wanted to situate a particle beam at a distance of 11.65mm in the positive z direction from the material slab, which emits charged particles at 5.482MeV in the -z direction to the centre of the top of the material. I set the particle beam to air, and I set the whole system to have a stating temperature of 100mK. I wanted to examine the heating of the material slab due to interaction with the particles, which I set to be released one per second, in a simulation lasting 3 seconds. Experimentally, the signal seen on the slab (a bolometer) has a time constant of roughly 15ms. I wanted to see if I can reproduce this in COMSOL.
I wanted to look at the heating effects in the material from the particles as well as, if possible, the energy dissipation in the material (how much is absorbed with different types of particle energies, how much isn't absorbed, maybe even scattering?). I'd also be interested in things like ballistic phonon propagation, but I'm not sure if COMSOL would allow for this or not. This is all time dependent, looking at 3 particle interactions over the course of 3 seconds and the energy/heat dissipation through that time.
I went through the tutorials and made myself a model in 3D, and the model unfortunately would not converge after about 1.5 days on a machine with 180GB of RAM. I unfortunately lost this file (Windows decided to update itself, and I hadn't properly saved it) but I rebuilt it this morning.
Questions:
Can COMSOL simulate what I need it to? I'm particularly interested in what I mentioned above, and in future I would like to expand on this with a more comprehensive model of the bolometer (sensor, the housing in which the detector is situated) and ultimately my lab is very interested in using software to simulate secondary particle generation in larger optical environments (the entire focal plane of a telescope, for example).
Is my model simply too large for it to handle? I'm sorry if my questions are very silly, but I'm new to this and the tutorials I've done, while remarkably clear, don't address the very specific things I'm trying to model. I can upload my model if you think it's something I've done wrong (pretty likely :) )
Also, the model was shown as being about 3.2GB of memory, when I have 180GB available. How can I make more memory available to COMSOL?
Thank you.
To start with, I went for a simple model of a cylindrical slab of type 2a diamond with r=3.5mm and t=40 micron. I then wanted to situate a particle beam at a distance of 11.65mm in the positive z direction from the material slab, which emits charged particles at 5.482MeV in the -z direction to the centre of the top of the material. I set the particle beam to air, and I set the whole system to have a stating temperature of 100mK. I wanted to examine the heating of the material slab due to interaction with the particles, which I set to be released one per second, in a simulation lasting 3 seconds. Experimentally, the signal seen on the slab (a bolometer) has a time constant of roughly 15ms. I wanted to see if I can reproduce this in COMSOL.
I wanted to look at the heating effects in the material from the particles as well as, if possible, the energy dissipation in the material (how much is absorbed with different types of particle energies, how much isn't absorbed, maybe even scattering?). I'd also be interested in things like ballistic phonon propagation, but I'm not sure if COMSOL would allow for this or not. This is all time dependent, looking at 3 particle interactions over the course of 3 seconds and the energy/heat dissipation through that time.
I went through the tutorials and made myself a model in 3D, and the model unfortunately would not converge after about 1.5 days on a machine with 180GB of RAM. I unfortunately lost this file (Windows decided to update itself, and I hadn't properly saved it) but I rebuilt it this morning.
Questions:
Can COMSOL simulate what I need it to? I'm particularly interested in what I mentioned above, and in future I would like to expand on this with a more comprehensive model of the bolometer (sensor, the housing in which the detector is situated) and ultimately my lab is very interested in using software to simulate secondary particle generation in larger optical environments (the entire focal plane of a telescope, for example).
Is my model simply too large for it to handle? I'm sorry if my questions are very silly, but I'm new to this and the tutorials I've done, while remarkably clear, don't address the very specific things I'm trying to model. I can upload my model if you think it's something I've done wrong (pretty likely :) )
Also, the model was shown as being about 3.2GB of memory, when I have 180GB available. How can I make more memory available to COMSOL?
Thank you.
1 Reply Last Post 15 apr 2016, 05:48 GMT-4
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Posted:
8 years ago
I've managed to get the simulator to converge, with a much smaller time step (I need it much finer, but I want to get it running first).
Now the problem is:
- I've set the particle inlet to come from the top of the upper cylinder at 0,0,-t_source. Yet most of the particles seem to get stuck at the top of the air column rather than going to the detector. It's also sending out lots of particles when it should only be sending 3.
- My simulation seems to think that the material slab will go from 100mK to 20mK during the course of the simulation. I had expected to see a very small temperature increase from the particles on the order of 15ms and maybe a couple of mK, but not a decrease.
- I think this all means I've defined something poorly but I'm not sure what.
Is anyone in a position to help? And I'm getting a file size error when I try to attach my file here.
Now the problem is:
- I've set the particle inlet to come from the top of the upper cylinder at 0,0,-t_source. Yet most of the particles seem to get stuck at the top of the air column rather than going to the detector. It's also sending out lots of particles when it should only be sending 3.
- My simulation seems to think that the material slab will go from 100mK to 20mK during the course of the simulation. I had expected to see a very small temperature increase from the particles on the order of 15ms and maybe a couple of mK, but not a decrease.
- I think this all means I've defined something poorly but I'm not sure what.
Is anyone in a position to help? And I'm getting a file size error when I try to attach my file here.