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Posted: 1 decade ago 2013年6月6日 GMT-4 16:23

[QUOTE] 3] the charge carriers i.e. electrons generated due to the laser light then get accelerated towards the electrode and within a few pico-seconds die out ; this phenomenon produces radiation in the terahertz region Guessing the physics required , I think I need something that will simulate: 1] charge density distribution over time on a semiconductor 2] lumped port (?) to simulate the electric potential 3] radiation equations from moving charge carriers Someone please help regarding any matter on this topic [/QUOTE] So, I happen to have a situation related to your own. I haven't quite figured out how to solve it though. I am looking to plot the EM radiation from electrons moving at relativistic speeds through a varying magnetic field (Synchrotron Radiation). Different acceleration medium, but the same general idea of an accelerating electron causing EM radiation at different wavelengths. I think the semiconductor module might be able to work for your charge density distribution in the semiconductor. And in the ACDC frequency domain, I have never used anything other than a sine wave, but it states that you can use it for square waves (they just state it needs to be periodic). As for the radiation equations, these can be relatively simple for single charges. It is my opinion that a combination of the RF and Particle Tracing modules would be able to plot the EM radiation generated by any structure. The Particle Tracing module would take the charge density distribution (or current density distribution) to trace out the path of a small set of electrons, similar to what actually happens in the semiconductor (just perhaps with less electrons than the actual case, but that's just a scaling factor). In looking at my EM textbook (graduate level Physics Electrodynamics, "Modern Electrodynamics" by Andrew Zangwill) using the Heaviside Feynman E and B radiation fields, all you should need to know is the retarded normal unit vector as a function of time (just points from the particle to the observation point as a function of time - retarded just means at the time radiation is emitted from the particle as compared to when the radiation is received at the observation point), along with a few constants. If anyone from COMSOL Support is reading this, this might be a simple way to solve for EM radiation due to general electron movement. :-) Unfortunately I am with you on the stuck end of things. Let me know if you have found anything out recently.