These are typical optical cavities:it is misleading to be confusing such an optical cavity with an EM Drive:
Radius=8.835cmtheta 30.7199°
Quote from: X_RaY on 03/11/2016 09:00 pmRadius 8.835cm*2=17.67cmRadius? I just need the height (in cm). This is a flat-end frustum. Want to see how it compares to what I found.
Radius 8.835cm*2=17.67cm
Quote from: Rodal on 03/11/2016 03:43 pmThe situation is worse: Monomorphic has accepted that he is aiming for a tolerance of only 1 mm. There is no way that a resonance is going to be achieved at optical frequencies that have a wavelength 200,000 times smaller than the frequencies of a typical EM Drive.There is no way that you are going to have reflection and resonance, with well-formed standing waves with a tolerance of only 1 mm at optical frequencies.How can one have resonance in a cavity having 1 mm tolerance, with an optical wavelength of 0.0006 mm As far as I understand, Monomorphic stated that his microwave frustum will have a tolerance (better than) 1mm, not the optical one. Most likely, the optical one will have optically aligned mirrors. Optical cavities can easily have Q of several millions, see: https://www.rp-photonics.com/q_factor.html Therefore, if we are to take Shawyer's theory as guide, it makes total sense that the thrust of an optical system with: -input power ~ 10W -quality factor > 1e6will be easily measurable. Like RonM, I too think that the optical EmDrive is a legitimate path to explore, at least in light of what we know so far. Of course, there might be other arguments against an optical EmDrive, in this case, let's hear them.
The situation is worse: Monomorphic has accepted that he is aiming for a tolerance of only 1 mm. There is no way that a resonance is going to be achieved at optical frequencies that have a wavelength 200,000 times smaller than the frequencies of a typical EM Drive.There is no way that you are going to have reflection and resonance, with well-formed standing waves with a tolerance of only 1 mm at optical frequencies.How can one have resonance in a cavity having 1 mm tolerance, with an optical wavelength of 0.0006 mm
Actually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific diameter and radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order. NOTE: Side walls are also mirrored, they are only shown clear here so you can see the interior of the frustum.
Quote from: SeeShells on 03/11/2016 04:16 pm...Consider these points.I wondered when RFPlumber's test when he first ran his tests he deformed the large plate from heating. I also wondered how a TE012 mode could provide the thermal profile on the large plate to warp it. It didn't match his COMSOL sim of a TE012. ...Shell, I noticed you keep mentioning that the large plate in my tests has been deformed from heating, I am not sure what makes you think so. I recall the exchange when someone asked whether the end plates on my frustum were flat or warped and I measured it and replied that they were maybe 1 mm warped in the center. My assumption back then was that the question referred to the quality of construction, and not to any deformation caused by the actual test. And my reply was also with an implicit assumption that this 1mm warping has been there from the start, and it was not the result of RF heating. I doubt one can cause any real warping on the plates with only 30W of energy (where a portion of it is then further leaking out as plain RF). Also, if I were to get any non-trivial amount of induction heating inside the frustum, I would have most likely witnessed "thrust" from all the hot air escaping through the gaps around side walls. It is possible that some of the thermal force I am attributing to the RF amplifier hot plate air convection could be coming from said hot air escaping from the frustum, but again, 30W is hardly enough to make any lasting deformation on the 0.5mm copper plates.
...Consider these points.I wondered when RFPlumber's test when he first ran his tests he deformed the large plate from heating. I also wondered how a TE012 mode could provide the thermal profile on the large plate to warp it. It didn't match his COMSOL sim of a TE012. ...
Quote from: SeeShells on 03/11/2016 07:52 pmCavity metal: Believe it was Aluminum It was copper. 0.5mm thick
Cavity metal: Believe it was Aluminum
Quote from: Monomorphic on 03/11/2016 05:24 pmActually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order.Thanks for the picture and the discussion. Does this have side-walls ? if so, what material is used for the side walls?
Actually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order.
I updated my post. The side walls are shown clear here so we can see the interior. They would be of the same material as the end-plate mirrors. Glass and vapor deposited aluminum or dialectric mirror.
The optical resonator is sometimes referred to as an "optical cavity", but this is a misnomer: lasers use open resonators as opposed to the literal cavity that would be employed at microwave frequencies in a maser. The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption. If the gain (amplification) in the medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially.
Quote from: Rodal on 03/11/2016 05:29 pmQuote from: Monomorphic on 03/11/2016 05:24 pmActually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order.Thanks for the picture and the discussion. Does this have side-walls ? if so, what material is used for the side walls?Quote from: Monomorphic on 03/11/2016 05:31 pmI updated my post. The side walls are shown clear here so we can see the interior. They would be of the same material as the end-plate mirrors. Glass and vapor deposited aluminum or dialectric mirror.I don't think that one needs the side walls, and actually the side walls will be detrimental to the effect being pursued.QuoteThe optical resonator is sometimes referred to as an "optical cavity", but this is a misnomer: lasers use open resonators as opposed to the literal cavity that would be employed at microwave frequencies in a maser. The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption. If the gain (amplification) in the medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially.At optical frequencies, your side walls are never going to be accurately straight and parallel to the optical ray and they are never going to be sufficiently smooth. They don't serve any useful function and worse, they are detrimental. It would be better not to have anything that can either reflect or refract the optical rays on the conical sides. Better leave it open.SUGGESTION: Test it both A) with sidewalls and B) WITHOUT side walls
Dr. Rodal, would minimal arc (concave) in the large reflector be beneficial? The mirrors below might do well? FL
...Were the measurements inside or outside of the frustum?
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.
Quote from: FattyLumpkin on 03/11/2016 11:41 pmDr. Rodal, would minimal arc (concave) in the large reflector be beneficial? The mirrors below might do well? FLTelescope mirror coating would need to be 10x skin depth thickness. 1x skin depth for Aluminium at 2,450MHz is 1.66um. http://chemandy.com/calculators/skin-effect-calculator.htmRf penetrates 5x skin depth. So the mirror coating needs to be at least 16.6um thick and pin hole free..Next issue is the end plates (mirrors) need to be in very good, continuous around the rim, electrical contact with the side walls to stop Rf leaks and potential arcing. Not an easy job but could maybe work if the Alum or Silver coating were thick enough.BTW I once hand ground & polished telescope mirrors, so know them well.Interesting though is using 2 in a long confocal arrangement might reduce the amount of eddy current losses in the side walls and if so, increase Q quote a bit. Or not?The shorter the focal length, the higher the phase distortion introduced upon each reflection.Phil
Quote from: Rodal on 03/11/2016 10:17 pmQuote from: Rodal on 03/11/2016 05:29 pmQuote from: Monomorphic on 03/11/2016 05:24 pmActually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order.Thanks for the picture and the discussion. Does this have side-walls ? if so, what material is used for the side walls?Quote from: Monomorphic on 03/11/2016 05:31 pmI updated my post. The side walls are shown clear here so we can see the interior. They would be of the same material as the end-plate mirrors. Glass and vapor deposited aluminum or dialectric mirror.I don't think that one needs the side walls, and actually the side walls will be detrimental to the effect being pursued.QuoteThe optical resonator is sometimes referred to as an "optical cavity", but this is a misnomer: lasers use open resonators as opposed to the literal cavity that would be employed at microwave frequencies in a maser. The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption. If the gain (amplification) in the medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially.At optical frequencies, your side walls are never going to be accurately straight and parallel to the optical ray and they are never going to be sufficiently smooth. They don't serve any useful function and worse, they are detrimental. It would be better not to have anything that can either reflect or refract the optical rays on the conical sides. Better leave it open.SUGGESTION: Test it both A) with sidewalls and B) WITHOUT side wallsBae, in his photonic laser thruster research, found that putting a gain media in the resonance cavity will cause the resonance to become highly resilient to misalignment of the reflectors (he had an Oh Sh*t moment when he held one of the mirrors in his hand and the thing remained in resonance). I'm not sure what adding a solid gain medium would do for an EMDrive, but it might be worth a shot to see if it can alleviate the need for extremely precise alignments.
Whoa, whoa, whoa!!! I thought this thread was about investigating whether Roger Shawyer's claims were physically realizable? To whit, an easily obtainable microwave oven magnetron, when launched into a "closed" resonant cavity, will develop thrust in reference to its environment, due to reaction against fields which can be incorporated within known Einstein/Newton physics? And as the Q increases, so does the thrust. Period.Again, why has no one TUNED THE SOURCE TO THE FRUSTUM??? Rather than spend EONS TRYING TO TRIM COPPER TO MATCH A RESONANT CAVITY TO AN UNMATCHABLE MICROWAVE SOURCE??? Some experiments and theories are getting way out of bounds, me thinks. Optical replications of an effect that has NEVER been replicated in its original configuration are beyond pointless.
Quote from: SteveD on 03/12/2016 01:29 amQuote from: Rodal on 03/11/2016 10:17 pmQuote from: Rodal on 03/11/2016 05:29 pmQuote from: Monomorphic on 03/11/2016 05:24 pmActually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order.Thanks for the picture and the discussion. Does this have side-walls ? if so, what material is used for the side walls?Quote from: Monomorphic on 03/11/2016 05:31 pmI updated my post. The side walls are shown clear here so we can see the interior. They would be of the same material as the end-plate mirrors. Glass and vapor deposited aluminum or dialectric mirror.I don't think that one needs the side walls, and actually the side walls will be detrimental to the effect being pursued.QuoteThe optical resonator is sometimes referred to as an "optical cavity", but this is a misnomer: lasers use open resonators as opposed to the literal cavity that would be employed at microwave frequencies in a maser. The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption. If the gain (amplification) in the medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially.At optical frequencies, your side walls are never going to be accurately straight and parallel to the optical ray and they are never going to be sufficiently smooth. They don't serve any useful function and worse, they are detrimental. It would be better not to have anything that can either reflect or refract the optical rays on the conical sides. Better leave it open.SUGGESTION: Test it both A) with sidewalls and B) WITHOUT side wallsBae, in his photonic laser thruster research, found that putting a gain media in the resonance cavity will cause the resonance to become highly resilient to misalignment of the reflectors (he had an Oh Sh*t moment when he held one of the mirrors in his hand and the thing remained in resonance). I'm not sure what adding a solid gain medium would do for an EMDrive, but it might be worth a shot to see if it can alleviate the need for extremely precise alignments. Whoa, whoa, whoa!!! I thought this thread was about investigating whether Roger Shawyer's claims were physically realizable? To whit, an easily obtainable microwave oven magnetron, when launched into a "closed" resonant cavity, will develop thrust in reference to its environment, due to reaction against fields which can be incorporated within known Einstein/Newton physics? And as the Q increases, so does the thrust. Period.Again, why has no one TUNED THE SOURCE TO THE FRUSTUM??? Rather than spend EONS TRYING TO TRIM COPPER TO MATCH A RESONANT CAVITY TO AN UNMATCHABLE MICROWAVE SOURCE??? Some experiments and theories are getting way out of bounds, me thinks. Optical replications of an effect that has NEVER been replicated in its original configuration are beyond pointless.
Quote from: Rodal on 03/11/2016 05:29 pmQuote from: Monomorphic on 03/11/2016 05:24 pmActually, you can create a concave-convex optical cavity in the shape of a frustum. In fact, the cavity length (5cm) is dictated by which concave and convex mirrors are available for purchase at specific radii. As pointed out by Dr. Rodal, the huge difference is the modes in an optical cavity will be much higher order.Thanks for the picture and the discussion. Does this have side-walls ? if so, what material is used for the side walls?Quote from: Monomorphic on 03/11/2016 05:31 pmI updated my post. The side walls are shown clear here so we can see the interior. They would be of the same material as the end-plate mirrors. Glass and vapor deposited aluminum or dialectric mirror.At optical frequencies, I don't think that one needs the side walls, and actually the side walls will be detrimental to the effect being pursued.QuoteThe optical resonator is sometimes referred to as an "optical cavity", but this is a misnomer: lasers use open resonators as opposed to the literal cavity that would be employed at microwave frequencies in a maser. The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption. If the gain (amplification) in the medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially.At optical frequencies, your side walls are never going to be accurately straight and parallel to the optical ray and they are never going to be sufficiently smooth. They don't serve any useful function and worse, they are detrimental. It would be better not to have anything that can either reflect or refract the optical rays on the conical sides. Better leave it open. (Of course, do wear eye protection).SUGGESTION: Test it both A) with sidewalls and B) WITHOUT side walls