Dear Steve, 1) before we involve in changing the source amplitude: Analysing the high-quality cavity ringdown by time-domain method running the whole time is *extremely* wasteful. In fact, the "harminv", or "filter diagonalization method" was designed to solve exactly this problem: from a short sample of the ringdown, it precisely recovers the frequencies, amplitudes and decay rates of all the modes. For what you do, harminv is orders of magnitude more efficient than the classical, Fourier-transform based approach!
2) Motivated to help you with your particular research, I spent several working days to implement a ready-to-use simulation which I published at https://github.com/FilipDominec/python-meep-utils/tree/master/example_ringdown_cylindrical_cavity It has proven to work efficiently, and it is ready for you. 3) I guess you are focused on the EmDrive experiments. While the topic has several red flags and appears highly suspicious for me, I admit that I am not knowledgeable enough to guess what makes different groups around the world report some positive results. Perhaps there is something completely new beyond my understanding. I am however pretty much convinced that the mysterious force effects can *not* be observed in the pure Maxwell-equation solver, such as MEEP. Therefore, MEEP can only play an auxiliary role for the design of resonant cavities, waveguides etc. Filip 2015-09-12 20:49 GMT+02:00, Steve <[email protected]>: > I need to see the decay of the fields in a resonant cavity excited with > a Gaussian source. (Bandwidth = 0.025 * center frequency) My thought > was: > > (at-time 1 (set! amplitude 0)) which does not work. I tried > (define amp 1) with > (amplitude amp) in the sources list, then > (at-time 1 (set! amp 0)) which didn't work either. And in these cases, > what I mean by "didn't work" is: > ?: 0 [procedure-property #<unspecified> arity] > > > Is there a way to change the source amplitude during the run? > > I really don't care about the source amplitude, I only want to view the > decay of the fields after the source turns off. Perhaps someone knows a > way to make the Gaussian source turn off so that the decaying fields can > be viewed. In this case, the quality factor of the resonant cavity is > very large so waiting for the source to turn off automatically doesn't > work as it never turns off. > > > _______________________________________________ > meep-discuss mailing list > [email protected] > http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
