First, how would you inject light into the frustum? I imagine that would require a hole in one of the end plates which would reduce the Q.
Phil, I don't know where you get your "mirror coating would need to be 10x skin depth thickness", or "Rf penetrates 5x skin depth". Skin depth is an engineering convenience, and nothing else, based on 1/e, ( inverse natural logarithm) of energy depletion of an electromagnetic wave in a conductor. In other words, the wave rapidly depletes within the conductor to the point that its field strength becomes effectively negligable.
Skin depth is defined as the distance below the surface where the current density has fallen to 1/e or 37% of its value at the surface.
P.S. Hanging around as I am very curious to see how the next experimenter is going about convincing herself/himself and others that the observed force is not the result of hot air.
SORRY I meant the height! 17.67cm
Quote from: X_RaY on 03/11/2016 09:10 pmSORRY I meant the height! 17.67cmOkay thanks. I was wondering why is was so short! Looks like you have TE311, albeit not as strong as the TE311 I was able to locate by simulating large numbers of frustum dimensions.
Here is a simple excel calculator to show how many reflections will occur from each end plate, depending on unloaded cavity Q 5 TC time, Rf freq and number of 1/2 resonant waves in the cavity.Example attached shows that for a TXXX3 resonant mode at 2.45 GHZ with a unloaded cavity Q of 86.2k, there would be 45,731 reflection from each end plate, for every cycle of Rf input, until the Rf energy is totally thermalised or converted into an externally usable force over 27.998usec. Which is a good life time for 1 cycle of 2.45GHz input Rf energy.45,731 reflections from each end plate is a lot to keep perfectly aligned and for them to not walk off to a wider separation point. Of course the end plate alignment also affects cavity Q as it affects wall losses.At least now we have a way to calc how many reflection will occur from each end plate if we get the cavity built perfect to 10x skin depth accuracy or better.
X-RaY, out of curiosity, does your spreadsheet indicate that TE211 is possible with a frustum length of ~18cm? End-plate radius can be arbitrary. I've been trying to find larger dimensions that resonate at that mode, as the one I found was only ~12cm in length.
@ Dr. Rodal,You may have already explained this but I can't rely on memory.It is difficult to find Drude model parameters for metals and I am looking for Silver. Plus, data that I do find is not guaranteed to compare to DeltaMass's detailed derivation for copper.Is it fair to simply multiply CU conductivity I'm using from DeltaMass by the ratio silver-conductivity divided by copper-conductivity where I use silver and copper conductivities from a published source? My source gives conductivities, Ag = 62.1 and CU = 58.5aero
Quote from: aero on 03/12/2016 07:35 pm@ Dr. Rodal,You may have already explained this but I can't rely on memory.It is difficult to find Drude model parameters for metals and I am looking for Silver. Plus, data that I do find is not guaranteed to compare to DeltaMass's detailed derivation for copper.Is it fair to simply multiply CU conductivity I'm using from DeltaMass by the ratio silver-conductivity divided by copper-conductivity where I use silver and copper conductivities from a published source? My source gives conductivities, Ag = 62.1 and CU = 58.5aeroPlease refresh my mindA) (preferably) by linking to my messages where I provided the Meep input for copper (I can't find them) or B) otherwise by giving me the actual Meep input you use for copper propertiesThanks
Optical polishing almost done. Before and after pics of small endplate of NSF-1701A
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