You know you the got EmDrive fever when you wake up at 3am and stare at mode shapes for two hours playing "spot the quadrupole moment". Based on previous discussions about the possibility of photons becoming massive while confined within waveguide and resonators, assuming this to be true, then the deformation of these resonant modes by virtue of the cavity geometry should produce mass quadrupole moments all over the place.
For instance, if I had a resonant sphere, I would have no quadrupole moment.
The quadrupole represents how stretched-out along some axis the mass is. A sphere has zero quadrupole. A rod has a quadrupole. A flat disk also has a quadrupole, with the opposite sign of the quadrupole of a rod pointing out from its flat sides. The rod is a sphere stretched along that axis and the disk is a sphere squashed along that axis. In general, objects can have quadrupole moments along three different axes at right angles to each other. (The quadrupole moment is something called a tensor.)
https://van.physics.illinois.edu/qa/listing.php?id=204
So yeah, I'm squashing massive spheres here at 5:25 in the morning and not really sure if this makes any sense. Is this the definition of pathological science?
Also thanks to @Rodal for offline discussion about TM212 vs TE012.
In this view, the distortion of the confined wavefunction by the cavity is relieved by acceleration. (in the direction which generates the opposite distortion) This is the source of the increase in entropy.
Still looking at the behavior under acceleration as opposed to the static force, ie. the force of the distorted wavefunction trying to restore itself. Each contribution examined so far has reduced the force as acceleration increases.
You know you the got EmDrive fever when you wake up at 3am and stare at mode shapes for two hours playing "spot the quadrupole moment". Based on previous discussions about the possibility of photons becoming massive while confined within waveguide and resonators, assuming this to be true, then the deformation of these resonant modes by virtue of the cavity geometry should produce mass quadrupole moments all over the place.
For instance, if I had a resonant sphere, I would have no quadrupole moment.
The quadrupole represents how stretched-out along some axis the mass is. A sphere has zero quadrupole. A rod has a quadrupole. A flat disk also has a quadrupole, with the opposite sign of the quadrupole of a rod pointing out from its flat sides. The rod is a sphere stretched along that axis and the disk is a sphere squashed along that axis. In general, objects can have quadrupole moments along three different axes at right angles to each other. (The quadrupole moment is something called a tensor.)
https://van.physics.illinois.edu/qa/listing.php?id=204
So yeah, I'm squashing massive spheres here at 5:25 in the morning and not really sure if this makes any sense. Is this the definition of pathological science?
Also thanks to @Rodal for offline discussion about TM212 vs TE012.
In this view, the distortion of the confined wavefunction by the cavity is relieved by acceleration. (in the direction which generates the opposite distortion) This is the source of the increase in entropy.
Still looking at the behavior under acceleration as opposed to the static force, ie. the force of the distorted wavefunction trying to restore itself. Each contribution examined so far has reduced the force as acceleration increases.
You mean like Pound-Rebka?
https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experimentBy the equivalence principle, it'd be the same thing for an EmDrive accelerating. Are you looking for an expression to show where the cavity would fall out of resonance while accelerating?
You know you the got EmDrive fever when you wake up at 3am and stare at mode shapes for two hours playing "spot the quadrupole moment". Based on previous discussions about the possibility of photons becoming massive while confined within waveguide and resonators, assuming this to be true, then the deformation of these resonant modes by virtue of the cavity geometry should produce mass quadrupole moments all over the place.
For instance, if I had a resonant sphere, I would have no quadrupole moment.
The quadrupole represents how stretched-out along some axis the mass is. A sphere has zero quadrupole. A rod has a quadrupole. A flat disk also has a quadrupole, with the opposite sign of the quadrupole of a rod pointing out from its flat sides. The rod is a sphere stretched along that axis and the disk is a sphere squashed along that axis. In general, objects can have quadrupole moments along three different axes at right angles to each other. (The quadrupole moment is something called a tensor.)
https://van.physics.illinois.edu/qa/listing.php?id=204
So yeah, I'm squashing massive spheres here at 5:25 in the morning and not really sure if this makes any sense. Is this the definition of pathological science?
Also thanks to @Rodal for offline discussion about TM212 vs TE012.
In this view, the distortion of the confined wavefunction by the cavity is relieved by acceleration. (in the direction which generates the opposite distortion) This is the source of the increase in entropy.
Still looking at the behavior under acceleration as opposed to the static force, ie. the force of the distorted wavefunction trying to restore itself. Each contribution examined so far has reduced the force as acceleration increases.
You mean like Pound-Rebka?
https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment
By the equivalence principle, it'd be the same thing for an EmDrive accelerating. Are you looking for an expression to show where the cavity would fall out of resonance while accelerating?
Yes, Pound-Rebka, as you call it, made a big impression on me at the time. You can see that result in the hypothesis calculation in the wiki.
It's not a "fall out of resonance", but there is an associated frequency shift.
Shawyer mentions on his website
A solution to the acceleration limitation of superconducting EmDrive engines has been found.
but he calls it a doppler shift...
I'm still looking around on his website for the "solution" but since superconducting=high Q, any frequency shifts could kill cavity resonance depending on how narrow the cavity bandwidth actually is.
Shawyer mentions on his website A solution to the acceleration limitation of superconducting EmDrive engines has been found.
but he calls it a doppler shift...
I'm still looking around on his website for the "solution" but since superconducting=high Q, any frequency shifts could kill cavity resonance depending on how narrow the cavity bandwidth actually is.
Read his last 3 papers.
Roger goes into some detail on how acceleration interacts with high Q cavities and the multiple methods they developed to deal with the effects.
Motivation alert - While some may be discouraged by the lack of any new info on emdrive, there is a "noble" reason to continue the search for new propulsion...while it may take decades, if we never start the race, we'll never finish it.
So, I give you a video link to the barge landing yesterday of SpaceX's Falcon 9. Carrying heavy propellant does have its disadvantages:
http://www.space.com/31653-spacex-rocket-landing-crash-droneship-video.html
Motivation alert - While some may be discouraged by the lack of any new info on emdrive, there is a "noble" reason to continue the search for new propulsion...while it may take decades, if we never start the race, we'll never finish it.
So, I give you yesterday's video link to the barge landing yesterday of SpaceX's Falcon 9. Carrying heavy propellant does have its disadvantages:
http://www.space.com/31653-spacex-rocket-landing-crash-droneship-video.html
There was a time when such concerns did not deter engineering studies of much more powerful space propulsion
, performing actual testing with conventional explosives to test the concept (instead of microNewton testing) (look at 8 min, for example), and famous physicists like Freeman Dyson were intimately involved:
20 Astronauts, all-up mission. Return time from Mars: 42 days. Mars surface payload: 150 metric tonshttps://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
Shawyer mentions on his website A solution to the acceleration limitation of superconducting EmDrive engines has been found.
but he calls it a doppler shift...
I'm still looking around on his website for the "solution" but since superconducting=high Q, any frequency shifts could kill cavity resonance depending on how narrow the cavity bandwidth actually is.
Read his last 3 papers.
Roger goes into some detail on how acceleration interacts with high Q cavities and the multiple methods they developed to deal with the effects.
I got it,
http://www.emdrive.com/IAC13paper17254.v2.pdf but what he's saying isn't making any sense.
...
This was just posted on the other site. Things are now making a little more sense.
Quote
Some quick notes.
The movies are mislabelled.
The TE01 mode should be TE10. It is not any reference to the frustum, but the dominant mode of the waveguides that are excited by the RF source. I should have not have mentioned the rectangular waveguide mode, it is confusing.
The Feko solver I'm using is method of moments.
The E-field magnitudes shown are not taken on the surface of the frustum (Where they are zero) but 2mm inside.
Feko calculates the standing waves. The animation in these movies are made my changing the phase of the RF sources so affecting the instantaneous E-field magnitude displayed. At 2.47 Ghz, this would be pretty fast!
The frustum walls are perfect conductors.
Note that the E-field scale is logarithmic. This can be misleading or helpful, I'm not sure. Will maybe try a linear scale next time.
I'll do an update with an improved model using copper and S-port measurements soon.
End Quote
No, it that does not make any sense
There is no such thing as mode shape TE10
n in TEmnp can never be zero. n can only be 1,2,3, etc. (*)
I already showed in https://forum.nasaspaceflight.com/index.php?topic=39004.msg1477698#msg1477698 that the mode shape looks like TM112. (**)
1) The tangential electric field parallel to a metal wall must be zero, it can never be non-zero
2) The quantum number "n" in modes TEmnp or TMmnp can never be zero, it must be equal to or greater than 1. There is no such thing as a mode TE10 !!!!!
______________________
(*) TE10 would mean that you have a wave-pattern in the circumferential direction but constant field in the radial direction, which is an obvious impossibility.
(**) It doesn't look like TE11p either. (At least there is such a thing as mode shape TE11p)
Explanation from IslandPlaya, who clears up what he meant by TE10 mode:
I hope this explains that if you feed RF into a frustum using a rectangular waveguide then the waveguide excitation has to be TE10 (at this freq.)
What the heck is happening in the frustum I don't know, but is the whole point of these sims.
I admit to not have completely read IslandPlaya's previous explanation in your message, SeeShells (I was multitasking, fast reading, and only thinking about the modes inside the EM Drive):
It is not any reference to the frustum, but the dominant mode of the waveguides that are excited by the RF source. I should have not have mentioned the rectangular waveguide mode, it is confusing.
The Feko solver I'm using is method of moments.
(
My fault for not carefully reading what IslandPlaya wrote: he was only referring to the mode shape he was feeding into the rectangular waveguide)
OK, so IslandPlaya explains that he was not referring to any mode shape inside the EM Drive frustum of a cone, when he referred to TE10, since there cannot be any such mode "TE10" inside the frustum (since "n" in TEmnp must be greater than zero in a cylindrical cavity or in a truncated cone cavity).
The mode shape shown by IslandPlaya's FEKO simulation looks like transverse magnetic mode: TM112.
NOTE 1: It would be better to show a linear numerical scale for the FEKO contour plot, instead of the logarithmic scale being used, because Maxwell's equations are linear and the electromagnetic fields inside a resonant cavity are better displayed with a linear scale.
NOTE2: It is great that IslandPlaya is using the Boundary Element Method (which the author of FEKO calls the "Method of Moments"). The Boundary Element Method can be shown to be much more accurate for solving a resonant cavity than the Finite Difference Method.
On the discussion on propagation, fields or modes within a cavity or waveguide.
Quick and sweet, at the vets trying to work on a cheap tablet.
Shell
https://www.cst.com/Academia/Examples/Hollow-Rectangular-Waveguide
A hollow waveguide is a transmission line that looks like an empty metallic pipe. It supports the propagation of transverse electric (TE) and transverse magnetic (TM) modes, but not transverse electromagnetic (TEM) modes. There is an infinite number of modes that can propagate as long as the operating frequency is above the cutoff frequency of the mode. The notation TEmn and TMmn are commonly used to denote the type of wave and its mode, where m and n are the mode number in the horizontal and vertical directions respectively. The mode with the lowest cutoff frequency is called the fundamental mode or dominant mode. For a hollow rectangular waveguide the dominant mode is TE10 and its E, H and J fields are shown in Fig. 2.
https://archive.org/stream/ClassicalElectrodynamics/Jackson-ClassicalElectrodynamics#page/n273/mode/2up
I've got to take my little Great Pyrenees in to be spade this morning and will be back on later.
Shell
The mode shape TE10 can exist in a rectangular waveguide (because the fields in a rectangular waveguide lateral dimensions a and b have the same cosine (or sine) functional distribution, so you can have TE01 or TE10).
There cannot be such thing as a "TE10" mode for a cylindrical waveguide or for a conical waveguide.
The reason for this is that in a cylindrical or a conical waveguide, "n" stands for the quantum number in the radial direction, and that "n=0" would mean a constant waveform in the radial direction, while varying in the circumferential direction (m>0), which is absolutely impossible to occur unless the electromagnetic fields are zero everywhere in the cylinder.
You cannot have a field that varies in the circumferential direction and does not vary in the radial direction.Similarly, it is impossible for a TE10p mode to exist in a cylindrical or a truncated cone cavity.
The Bessel function solutions for a cylindrical cavity have solutions only for n equal to or greater than 1:
http://wwwal.kuicr.kyoto-u.ac.jp/www/accelerator/a4/besselroot.htmlx
On the discussion on propagation, fields or modes within a cavity or waveguide.
Quick and sweet, at the vets trying to work on a cheap tablet.
Shell
https://www.cst.com/Academia/Examples/Hollow-Rectangular-Waveguide
A hollow waveguide is a transmission line that looks like an empty metallic pipe. It supports the propagation of transverse electric (TE) and transverse magnetic (TM) modes, but not transverse electromagnetic (TEM) modes. There is an infinite number of modes that can propagate as long as the operating frequency is above the cutoff frequency of the mode. The notation TEmn and TMmn are commonly used to denote the type of wave and its mode, where m and n are the mode number in the horizontal and vertical directions respectively. The mode with the lowest cutoff frequency is called the fundamental mode or dominant mode. For a hollow rectangular waveguide the dominant mode is TE10 and its E, H and J fields are shown in Fig. 2.
https://archive.org/stream/ClassicalElectrodynamics/Jackson-ClassicalElectrodynamics#page/n273/mode/2up
I've got to take my little Great Pyrenees in to be spade this morning and will be back on later.
Shell
The mode shape TE10 can exist in a rectangular waveguide (because in a rectangular waveguide the lateral dimensions have equal importance, so you can have TE01 or TE10).
There cannot be such thing as a "TE10" mode for a cylindrical waveguide or for a conical waveguide. The reason for this is that in a cylindrical or a conical waveguide, "n" stands for the quantum number in the radial direction, and that "n=0" would mean a constant waveform in the radial direction, which is absolutely impossible to occur unless the electromagnetic fields are zero everywhere in the cylinder.
Correct. Digging this early morning through Jackson's and the web I found that out too.
You image looks like a TM112 in the cavity but it shouldn't be. Need to think on this a bit.
...
Correct. Digging this early morning through Jackson's and the web I found that out too.
You image looks like a TM112 in the cavity but it shouldn't be. Need to think on this a bit.
Why shouldn't it be TM112? It is possible to excite TM112 and that's what FEKO shows.
This reminds me of when you and aero were trying to excite TE012 with Meep in cavities using antennas, and you kept exciting TM modes instead...
Motivation alert - While some may be discouraged by the lack of any new info on emdrive, there is a "noble" reason to continue the search for new propulsion...while it may take decades, if we never start the race, we'll never finish it.
So, I give you yesterday's video link to the barge landing yesterday of SpaceX's Falcon 9. Carrying heavy propellant does have its disadvantages:
http://www.space.com/31653-spacex-rocket-landing-crash-droneship-video.html
There was a time when such concerns did not deter engineering studies of much more powerful space propulsion , performing actual testing with conventional explosives to test the concept (instead of microNewton testing) (look at 8 min, for example), and famous physicists like Freeman Dyson were intimately involved:
20 Astronauts, all-up mission. Return time from Mars: 42 days. Mars surface payload: 150 metric tons
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
The interesting thing is that, from all indications, the ORION would actually have worked and would have opened up large scale human interplanetary travel. It would also have had the unfortunate side effect of producing nasty EMPs and wide scale dispersion of radionucleotides.
...
The interesting thing is that, from all indications, the ORION would actually have worked and would have opened up large scale human interplanetary travel. It would also have had the unfortunate side effect of producing nasty EMPs and wide scale dispersion of radionucleotides.
In comparison with the EM Drive, Orion, although "very difficult to test" because it involved the release of radiation in the atmosphere, it was actually tested (using conventional explosives) and a famous physicist like Freeman Dyson was involved, while the EM Drive is being only researched in labs under 1 milliNewton forces for over a decade, with never-ending discussions about whether the results are thermal and electromagnetic experimental artifacts. Canane and Shawyer (the "S" actually stands for Satellite) discussed testing the EM Drive in Space but it has never actually been done...
NSF-1701A Update -
Today, ventured out into the lake-effect snowstorm and picked up a sheet of 19 mil plain aluminum and some aircraft snips. Here's the plan, disassemble NSF-1701 top and bottom plates. Insert aluminum sheet, mark and cut for fit inside copper mesh. Use the solid brass tuning rings to adjust solid aluminum sidewalls for ideal dimensions for resonance to my original mag using VNA.
Tape aluminum and use as either a template for new copper OR fill it to create a form. The form can then be used as "cast" for shaping new copper sheet. Not sure the best approach yet. The solid form would allow spinning copper over it and also properly size/solder a new sheet of copper if I went that way with it. Comments welcomed. Ideas on form filler material? Epoxy resin may not stand up to solder temps, but would be OK for spinning.
Edit - here is a link to copper mesh resonance and original magnetron spectrum:
http://forum.nasaspaceflight.com/index.php?topic=38577.msg1446931#msg1446931I will tune the new frustum for 2455 MHz, which should capture the majority of the mag's energy.
...
The interesting thing is that, from all indications, the ORION would actually have worked and would have opened up large scale human interplanetary travel. It would also have had the unfortunate side effect of producing nasty EMPs and wide scale dispersion of radionucleotides.
In comparison with the EM Drive, Orion, although "very difficult to test" because it involved the release of radiation in the atmosphere, it was actually tested (using conventional explosives) and a famous physicist like Freeman Dyson was involved, while the EM Drive is being only researched in labs under 1 milliNewton forces for over a decade, with never-ending discussions about whether the results are thermal and electromagnetic experimental artifacts. Canane and Shawyer (the "S" actually stands for Satellite) discussed testing the EM Drive in Space but it has never actually been done...
We're probably stuck in the rocket world for lifters for quite a while. Seems to me that previous theories are putting the cart before the horse. IOW, start small in space where impact could be immediate, scale up if possible and then determine if its lift-capable. I have my suspicion that emdrive will never be useable on the ground. I could easily be wrong, but consider the huge amount of RF to extract a mN force. kg lifters? Probably enough RF to toast half a county is my bet.
I think (me only) that what we really have is a small opening to new space-flight technologies, nothing for ground-based applications. I know there's people claiming this will be soon, but my radar goes off on comments like this.
I'd suggest we do the best we can and focus on it being a replacement for ION or Plasma technologies.
Einsteins paper...posted elsewhere, linked here as well. A cylinder in space and imparted motion due to radiation applied:
http://einsteinpapers.press.princeton.edu/vol2-trans/214?ajax
This (the mass of a body changes with its energy content) was precisely the point made by NSF user WarpTech, (Todd we miss ya
) in classic exchanges regarding conservation of energy, that he had in these threads with NSF user DeltaMass (we miss you too
). Unfortunately the EM Drive's claimed self-acceleration does not appear to be explainable on this basis because of...the relatively puny energy change involved in the EM Drive cannot be used to justify the claimed "anomalous force" (off by orders of magnitude...)
Back to the whiteboard and keep your eyes on the Notsosureofit hypothesis, who remains here (from time to time
)...
, performing actual testing with conventional explosives to test the concept (instead of microNewton testing) (look at 8 min, for example), and famous physicists like Freeman Dyson were intimately involved:
) in classic exchanges regarding conservation of energy, that he had in these threads with NSF user DeltaMass (we miss you too