About cavity energy.When an optimal impedance match is achieved between the RF source and its load (the cavity), all the forward power gets dissipated in the cavity walls as real ohmic heat. Thus maximum heating corresponds to maximum energy within the cavity, the condition that is being sought. Notionally then it would be possible to keep the impedance match optimal over temperature changes by simply monitoring the cavity temperature (I'm assuming that the mode does not switch). The latency of thermal feedback is slower than a 1-port or 2-port VSWR measurement, it's true, but it should nevertheless work well. And it can be made contactless.Because there's no free lunch, a perfectly matched high-Q cavity and a perfectly matched low-Q cavity will dissipate exactly the same amount of power in ohmic heating for the same input power. At least, that's the theory.

I understand. I am pointing out that the number you're quoting has dubious physical significance. The last 6 digits - at least - have no effect on anything real. . That's beyond debate, so I have no problem stating these facts.

@Rodal: Well, because the specific heat of copper isn't zero, it takes a finite time to incur a given temperature rise for a given power input. And when there's an impedance mismatch, the dissipated power will fall and so the corresponding temperature changes will be less than in the matched condition.On the other hand, measurable mismatch changes are sensed at the ports with response times on order roughly the cavity dimensions divided by the speed of light. This is far faster than measurable temperature changes.However, if the EmDrive is actually generating thrust, the statement about the equivalence of high- and low-Q dissipation may not be true. That's really the reason I'm pointing this out.

Quote from: deltaMass on 08/06/2015 06:56 AMQuote from: aero on 08/06/2015 04:13 AMQuote from: rfcavity on 08/06/2015 03:43 AMWhat mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?The lattice is 0.2747255683428571 meters longOh please.To 16 significant digits.

Quote from: aero on 08/06/2015 04:13 AMQuote from: rfcavity on 08/06/2015 03:43 AMWhat mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?The lattice is 0.2747255683428571 meters longOh please.

Quote from: rfcavity on 08/06/2015 03:43 AMWhat mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?The lattice is 0.2747255683428571 meters long

What mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?

Quote from: deltaMass on 08/06/2015 06:29 PMI understand. I am pointing out that the number you're quoting has dubious physical significance. The last 6 digits - at least - have no effect on anything real. . That's beyond debate, so I have no problem stating these facts.You're being pedantic about significant digits in a numerical simulation for no apparent purpose but undermining its credibility, when it really doesn't matter.

Quote from: RotoSequence on 08/06/2015 06:49 PMQuote from: deltaMass on 08/06/2015 06:29 PMI understand. I am pointing out that the number you're quoting has dubious physical significance. The last 6 digits - at least - have no effect on anything real. . That's beyond debate, so I have no problem stating these facts.You're being pedantic about significant digits in a numerical simulation for no apparent purpose but undermining its credibility, when it really doesn't matter.Please bear in mind, when one does iterations with float numbers, a seemingly ridiculous accuracy can actually matter. Since float operations are limited in accuracy, each iteration, will result in more inaccurate numbers. Bottom line: It will add up and might actually be significant at the end.

Quote from: meberbs on 08/06/2015 06:13 AM...The key is that when a photon reflects off something twice the photon's momentum is transferred, but this only corresponds to a tiny fraction of the photon's energy. This means the photon is barely redshifted and can continue transferring nearly the same momentum each time until: the mirror accelerates enough to cause large redshift, the photon is absorbed by a mirror which converts the energy to heat rather than directed kinetic energy, or the photon misses the reflector.Since I was curious about the conservation of energy for a single reflection at 0 velocity (when normally equations give 0 doppler shift), I worked out the expected doppler shift. This was based off conservation of momentum and energy, keeping around terms that are normally neglected in doppler shift, since the momentum transfer to objects is negligible in most applications.The result is:v2/v1 = sqrt(a^2 + 4*a +1)-a-1, where a=m*c^2/(h*v1)where v2 is the new frequency, v1 is the starting frequency, m is the mass of the mirror that the photon reflects off, h and c are the usual constants.To get an idea of how little energy is transferred in this case, for a photon at 3 GHz, and a mirror mass of only 1e-35 kg, the ratio is 0.999997. Any actual physical mirror with reasonable mass would result in an immeasurably small doppler shift even for much higher frequencies. Repeated reflection just means you get to convert more of the photons energy into the desired form (kinetic energy of your craft) before the rest gets lost in some way. bolding addedOn a more EM drive related note, photon drive amplification from reflections against test chamber walls was one of my first guesses at possible sources of the EM drive thrust.Nice work.Clearly explains why EMDrive generated Force scales with Q and why a high Q EMDrive can deliver much more Force than can a photon rocket.In an EMDrive ....... Q Rules

...The key is that when a photon reflects off something twice the photon's momentum is transferred, but this only corresponds to a tiny fraction of the photon's energy. This means the photon is barely redshifted and can continue transferring nearly the same momentum each time until: the mirror accelerates enough to cause large redshift, the photon is absorbed by a mirror which converts the energy to heat rather than directed kinetic energy, or the photon misses the reflector.Since I was curious about the conservation of energy for a single reflection at 0 velocity (when normally equations give 0 doppler shift), I worked out the expected doppler shift. This was based off conservation of momentum and energy, keeping around terms that are normally neglected in doppler shift, since the momentum transfer to objects is negligible in most applications.The result is:v2/v1 = sqrt(a^2 + 4*a +1)-a-1, where a=m*c^2/(h*v1)where v2 is the new frequency, v1 is the starting frequency, m is the mass of the mirror that the photon reflects off, h and c are the usual constants.To get an idea of how little energy is transferred in this case, for a photon at 3 GHz, and a mirror mass of only 1e-35 kg, the ratio is 0.999997. Any actual physical mirror with reasonable mass would result in an immeasurably small doppler shift even for much higher frequencies. Repeated reflection just means you get to convert more of the photons energy into the desired form (kinetic energy of your craft) before the rest gets lost in some way. bolding addedOn a more EM drive related note, photon drive amplification from reflections against test chamber walls was one of my first guesses at possible sources of the EM drive thrust.

As I'm sitting here soaking wet I'm thinking what in the heck am I doing... lmao. The line broke on my 2100 psi industrial power washer from the wand... PANDEMONIUM insued! I couldn't get close to the power washer to shut it off as it was like a Buster Keaton skit with it flailing around spraying everything in water and soap (have a container to suck up soap). Sigh. Ran into the house about 150 foot away and shut it off squishing all the way.I guess I need another hose. Fun times at the Egor Shop of Horrors.BBL after I dry myself off .. So how's your day going?Shell http://www.gifwave.com/media/816070_halloween-young-frankenstein-igor-halloweeen-countdown_200s.gif

As I'm sitting here soaking wet I'm thinking what in the heck am I doing... lmao. The line broke on my 2100 psi industrial power washer from the wand... PANDEMONIUM insued! I couldn't get close to the power washer to shut it off as it was like a Buster Keaton skit with it flailing around spraying everything in water and soap (have a container to suck up soap). Sigh. Ran into the house about 150 foot away and shut it off squishing all the way.I guess I need another hose. Fun times at the Egor Shop of Horrors.BBL after I dry myself off .So how's your day going?Shell http://www.gifwave.com/media/816070_halloween-young-frankenstein-igor-halloweeen-countdown_200s.gif

Quote from: TheTraveller on 08/06/2015 07:28 AM...In an EMDrive ....... Q Rules[/b]Q is only half of the story. Mr. Shawyer's force equation translates to Q times input power times (small diameter force per watt minus large diameter force per watt).Theoretically you can increase the small diameter force per watt exponentially by approaching the cut-off size of the equivalent waveguide.I played with the numbers yesterday for F=2P/Vg -> F=2*P*Sqrt(1-(c/(2*(a+x)*f))^2) and found ...for 2a = lambda, f =2.45e9, P=1xFx>=lambda/22/C 6.6e-910e-21.3e-810e-33.73e-810e-61.16e-610e-93.6e-4Note: 10e-9 refers to the calculator version of e. i.e. 2*10e-9 = 2*10^-9By carefully controlling the wide dimension of the reflector you can increase the resultant force by 4 orders of magnitude.Caution:I haven't sanity or double checked these numbers.Submicrometer (10e-6) precision is likely impossible to recognize in a physical system. Thermal distortion = flooby dust interference. It also seems pointless if you are using a wideband Rf source.... so that would be a nifty way to add a couple of orders of magnitude of thrust to your flashlight+skateboard photon rocket.Disclaiming again, I probably broke the math.

...In an EMDrive ....... Q Rules[/b]

Quote from: SeeShells on 08/06/2015 07:11 PMAs I'm sitting here soaking wet I'm thinking what in the heck am I doing... lmao. The line broke on my 2100 psi industrial power washer from the wand... PANDEMONIUM insued! I couldn't get close to the power washer to shut it off as it was like a Buster Keaton skit with it flailing around spraying everything in water and soap (have a container to suck up soap). Sigh. Ran into the house about 150 foot away and shut it off squishing all the way.I guess I need another hose. Fun times at the Egor Shop of Horrors.BBL after I dry myself off .. So how's your day going?Shell http://www.gifwave.com/media/816070_halloween-young-frankenstein-igor-halloweeen-countdown_200s.gifPlease be careful, as we are all worried about your safety. It would be nice to have somebody helping you in case something goes wrong: for example you could have slipped on the wet floor etc. Please don't work alone. Safety first.

Quote from: SeeShells on 08/06/2015 07:11 PMAs I'm sitting here soaking wet I'm thinking what in the heck am I doing... lmao. The line broke on my 2100 psi industrial power washer from the wand... PANDEMONIUM insued! I couldn't get close to the power washer to shut it off as it was like a Buster Keaton skit with it flailing around spraying everything in water and soap (have a container to suck up soap). Sigh. Ran into the house about 150 foot away and shut it off squishing all the way.I guess I need another hose. Fun times at the Egor Shop of Horrors.BBL after I dry myself off .So how's your day going?Shell http://www.gifwave.com/media/816070_halloween-young-frankenstein-igor-halloweeen-countdown_200s.gifWell, I'm happy for you that your experimental setup wasn't further along. I hope you didn't manage to destroy anything of significance?