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#2380 by SeeShells on 29 Jan, 2016 20:03
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...
Right now I like the Foobie Dust theory because their simply isn't enough raw data that's been tested for and released to draw conclusions or even a glimmer of one.
I don't have the faith to just build something that involves high-Q modes and hope it works, or that within a few hours/weeks/months of tinkering with it I'll hit the sweet-spot. As you've found with simulations, there's all kinds of ways it can vibrate. I know from my experience with EM and acoustics how mercurial, crystalline gas-like, they are. I'm convinced slow group-velocity/dispersion to filter out, and inductive skin loss to dissipate the lower-Doppler sideband is the cause of any force. I have a basis to research, calculate, design and troubleshoot. If I'm right.
I would hope your right on your theory, it would save me a lot of grunt time. Although you do need data to flesh out your theories. You're correct with the problems of EM and acoustics and well said. Better than my analogy ... I always thought of them like trying to push around jello with jello tools in a stainless steel bowl.
When I started this project there were just as many theories and a larger quantity of thoughtful guesses. The data was slim but there were a few things that stood out from the noise. See Attachment. This is what I built to test and not only was it built to test one mode of operation it was built to test several modes and Qs. The DUT needed to be able to show data from potentially just a pressure gradient non-accelerating force to a device that would show acceleration.
This was the basis for the multiple test designs with the DUT and in one test stand. Someone has to be able to step up to the plate and do the grunt work because theories are not cutting it without some more data.
It also can provide some confirming data to several robust theories....
Is there a difference in measured thrusts tuning across a resonate point, effectively through cutoffs? Another biggie.
As I've stated, closer to cutoff, slower group velocity and better sideband filtering but lower Q/momentum. A balance will need to be struck.
This is going to be one of the more interesting tests to actually measure thrusts and compare to where in the cutoff region that it's maximized.Is there a difference in sweeping through the cutoffs and the mode generated?
Shawyer's design factor is a good starting point, I guess. Until we nail down the why and how.
Is there a difference in observed static pressure measurements and acceleration, does the drive provide a steady state of acceleration? A huge biggie.Do Diamagnetic materials truly increase the thrusts? Maybe.
I suspect any material, other than ultra low-loss (@ 2.5 Ghz or whatever Fr) Alumina or perhaps your quartz are going to devastate Q and thrust. There is a paper I can dig up describing using an alumina marble to boost cavity Q from ~10k into the millions for accelerators. IIRC, the idea was to pull the electric field and current away from the sidewalls. But what would concern me is Fresnel dragging. If a material has a significant Epsilon-r, that means its atomic dipoles are polarized. Atomic dipoles which will move in the inertial lab-frame of the frustrum, Fresnel-dragging the mode in the lab frame and subtracting from the Doppler-shift and consequently thrust.
The Be ceramic Alumina plate is on the outside of the cavity with the inside layer .80mm O2 Free copper sheeting. You see the same material used in the semi industry for mounting Rf componets. ie: cell phones etc.
The Quartz rod
offers
Permeability
Extreme Hardness
Very Low Coefficient of Thermal Expansion
Resistance to High Temperature
High Chemical Purity
High Corrosion Resistance
Extensive Optical Transmission from Ultra-Violet to Infra-Red
Excellent Electrical Insulation Qualities
Remarkable Stability Under Atomic Bombardment
http://www.technicalglass.com/technical_properties.html
From what I've seen the issues facing builders and decreased Q have been build quality and compensation for thermal effects.
How much remains to be calculated. Now that I've found some equations and theory, I can start worrying about how to calculate and if the problems are tractable on my pathetic pc. Then I can (or not) write something up for the Wiki.
Along with the various conjectures and lists of questions would go corresponding predictions and experiments to falsify. Perhaps my NEWSOP more than any other is easiest to falsify. After having a thrust-producing frustrum, you re-tune it with a little lossy material at top/bottom that's been calculate to attenuate the upper/lower sideband, and then see if the thrust reverses 180
I'll find it very interesting investigating your hypothesis
Shell
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#2381 by zen-in on 29 Jan, 2016 21:01
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I don't see how to justify it as a closed system either, that is, a contained system with NO interaction with the outside. Plenty of things go through the copper walls, gravity, spacetime, neutrinos, static magnetic fields...the list goes on. The problem is finding the interaction which can conserve momentum and not be orders of magnitude off the mark.
I'm right with you on this. The only clue we have now is Dr White's interferometer which I think measured spatial expansion along the axial length of a common cavity, about 40 times what air heating would have created. Guess we have to determine the mechanism that created it, the dimensional shape of the distortion (if there is any) and the consequences of its creation.
If I might use a basic analogy of a single rubber band...assume both ends are taped down to the top of a desk. Draw a dot on the band, about halfway. Grab that dot and pull towards one fixed end. The band opposite that direction being stretched has expanded, increasing its potential energy. The band in the direction it is pulled is compressed, lowering its potential energy in balance...Release the dot...it returns to equilibrium towards the expanded direction.
Expanded space axially might mean there is compressed space in the opposite direction axially. Just like some of the Alcubierre illustrations I have seen. The dot or the frustum is driven towards expanded space. If this analogy were correct, it might mean that an em pulse is required, not CW.
I don't believe there is anything new in those interferometer measurements. I discussed that last year. This is what I wrote:Quote from: zen-in « Reply #1961 on: 04/24/2015 08:36 PM » EM Drive Developments - related to space flight applications - Thread 2There is really nothing here. I have worked with much more precise interferometers and know that laser fringes are inherently noisy. Any thermal gradiant, vibration, or EM energy pulses will show up as a phase shift. That is one of the biggest problems in achieving high resolution spectroscopy with FTIR. Those interferometers are built to a much higher precision than the White Juday experiment and with accurate mirror alignment a narrow band monochromatic interference pattern will cover half the optical aperture. This is what is shown in the diagram from White's paper, reproduced below. (first image) The 3-D plot is just a 3-D rendering of an interference pattern. The Z-scale has made up numbers and no dimension. In actual fact the difference in path length indicated by this interference pattern is 633/4 nM and is just what normal interference patterns look like. Applying a 3-D toolkit to an interference pattern image does not prove there is a warp field. It is just a flashy powerpoint slide.
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#2382 by JasonAW3 on 29 Jan, 2016 21:19
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So, if I understand this correctly, there doesn't appear to be any sort of optical distortion beyond that which would be generated by the heat produced in the experiment.
I assume that these measurements were taken at normal sea level pressure? If so, it would be easily explainable as heat generated background noise. IE. heat transfer from the copper to the air.
If these measurements were taken in a vacuum, then the explanation becomes a bit more problematic. But it looks like it would still be within the noise range. -
#2383 by rfmwguy on 29 Jan, 2016 21:29
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Thanks for your info Zen...glad to see you back. Not sure if I read your post the first time and was not aware there was a counter-point to it...but my memory is Rodal/10x106
If you were going to put an estimate on it, what percentage would you give that it is not space-time distortion?
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#2384 by zen-in on 29 Jan, 2016 22:17
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Thanks for your info Zen...glad to see you back. Not sure if I read your post the first time and was not aware there was a counter-point to it...but my memory is Rodal/10x106
I would give it 0%. My understanding of their protocol is as follows:
If you were going to put an estimate on it, what percentage would you give that it is not space-time distortion?
(1) Align the interferometer so there is no fringe at the detector.
(2) Energize the capacitor device and acquire an image of the interference pattern.
The White-Juday interferometer does not have a moving mirror so it can't measure the phase shift in realtime. Besides this, the experiment was not done in a vacuum or controlled atmosphere and there was no differential test. By differential test I mean measuring the same interferogram with no RF energy and using that as a reference. The W-J interferometer is not a very precise optical instrument. When I was working for the FTIR company we would use a narrow-band Neon source (a frosted-glass light box with a large Neon bulb in it) to roughly align the interferometer with the moving mirror stopped. After only 1 or 2 fringes covered the 3" Dia. optical path we could align the fixed mirror for maximum interferogram amplitude with a broadband IR source. That was always very tricky because the interferogram's S/N would climb by several orders of magnitude. Only then could you acquire spectra. This is where they would have to be to convince me there was any EM effect being seen. But their instrument does not have the required stability and a camera is not fast enough. With a stable instrument they could collect a sample with no EM in it and then ratio it with one that has the EM capacitor field or whatever it is they sampled. If there is a phase shift it will show up. This could be done with a narrow band source just as well. The interferogram would just be a narrow spike. Below is a typical broadband IR interferogram from an FTIR spectrometer. When an FFT is done on this signal an audio frequency signal that is the passband spectra is produced. For a narrow-band source the only useful information would be the phase shift. One of the instruments we sold was a film thickness guage. It measured the thickness of films deposited on Silicon wafers by measuring the phase shift between the interference patterns reflected from each interface. While those interferometers were less precise and had a smaller aperture, they used a moving mirror. DC drift, heat, and many other factors conspire against optical measurement techniques that don't use differential methods.
Here is a paper on narrow band spectroscopy with FTIR-
http://link.springer.com/chapter/10.1007%2F978-1-4614-7804-1_18#page-1
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#2385 by rfmwguy on 29 Jan, 2016 22:48
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Ok zen...your professional work experience trumps everything I've read. If its not space time distortion, imo, the chances of finding a closed system solution has been dramatically diminished as I cannot imagine coe/com violations.Thanks for your info Zen...glad to see you back. Not sure if I read your post the first time and was not aware there was a counter-point to it...but my memory is Rodal/10x106
I would give it 0%. The White-Juday interferometer does not have a moving mirror so it can't measure the phase shift. Besides this, the experiment was not done in a vacuum or controlled atmosphere and there was no differential test. By differential test I mean measuring the same interferogram with no RF energy. When I was working for the FTIR company we would use a narrow-band Neon source (a frosted-glass light box with a large Neon bulb in it) to roughly align the interferometer with the moving mirror stopped. After only 1 or 2 fringes covered the 3" Dia. optical path we could align the fixed mirror for maximum interferogram amplitude with a broadband IR source. That was always very tricky because the interferogram's S/N would climb by several orders of magnitude. Only then could you acquire spectra. This is where they would have to be to convince me there was any EM effect being seen. Collect a sample with no EM in it and ratio it with one that has the EM or whatever it is they sampled. If there is a phase shift it will show up. This could be done with a narrow band source just as well. The interferogram would just be a narrow spike. Below is a typical broadband IR interferogram from an FTIR spectrometer. When an FFT is done on this signal an audio frequency signal that is the passband spectra is produced. For a narrow-band source the only useful information would be the phase shift.
If you were going to put an estimate on it, what percentage would you give that it is not space-time distortion? -
#2386 by CuriousDreamer on 30 Jan, 2016 00:05
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Guess we can finally agree that "New Physics" is an appropriate Heading for our 21st Century discussions:
<snip>
the theory of relativity has given many correct predictions since its inception at the beginning of the 20th century. It must then be incorporated into all of the laws that underlie physics."
<snip>
I would like to point out that Ptolemy's (100A.D. – 170A.D.) model of the solar system was able to predict the movements of the planets and stars to an extremely accurate level, even though the model placed the earth in the center of the solar system and the planets moved in epicycles. Even when Copernicus (1473A.D. - 1543A.D.) proposed a sun centered model, it wasn’t until Newton (1642A.D. – 1726A.D.) made Copernicus’ planetary orbits elliptical that the sun centered model was accepted.
Will we learn that relativity is completely wrong even though it makes such nice predictions? And will we find that some dismissed theory is actually closer to reality and only needs a minor adjustment?
Maybe the EMdrive will be the equivalent of looking down on the solar system and seeing how it really works, but with relativity! Or maybe we will be heating up frozen dinners with our wonderful new inventions…
~Dreamer -
#2387 by spupeng7 on 30 Jan, 2016 00:08
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An interesting (if way over my head) paper from Fernando Minotti of Argentina, http://arxiv.org/pdf/1302.5690.pdf
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#2388 by Rodal on 30 Jan, 2016 00:20
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An interesting (if way over my head) paper from Fernando Minotti of Argentina, http://arxiv.org/pdf/1302.5690.pdf
Yes, we actually examined this paper in previous threads. Please notice that:Quote from: MinottiThe weakest part of the theory seems to be that there is no clear way of preventing large gravitational effects due to the magnetic field of the Earth, as predicted by Eq. (17)
In other words, Minotti writes that the theory used in Minotti's paper is in conflict already with our experimental knowledge of the magnetic field around the Earth, so we already know that the theory discussed in the paper cannot be a good model of reality.
Still, Minotti's mathematical analysis is good and useful, as he obtains an exact solution for resonance of the EM Drive under Maxwell's equations which is even more elegant than Greg Egan's solution. Dr. Frasca (NSF user StrongGR) used Minotti's paper as one of his references for his paper on the EM Drive that we discussed in previous threads:
Einstein-Maxwell equations for asymmetric resonant cavities
Marco Frasca
http://arxiv.org/abs/1505.06917v1
(*) It is interesting that you point out that Minotti is from Argentina, because although a small country bordering on the South Pole, it has contributed already three important contributions to the EM Drive/propellant-less literature:
1) Minotti's paper
2) Brito's papers on propellant-less drives, which predate Shawyer's EM Drive paper and predate several of Woodward's papers as well
3) Marini and Galian's paper on the AIAA Journal of Propulsion and Power, detailing experiments that nullified a Mach-Lorentz type of propellant-less thruster that at one point in time (no longer) was being proposed by Woodward and associates. -
#2389 by Rodal on 30 Jan, 2016 01:03
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TheTRAVELLER's test: CONTOUR PLOTS COMPARISON OF norm of ELECTRIC FIELD in Decibel scale, EXACT SOLUTION vs. FEKO (Boundary Element Method) model
Continuing the discussion from this message ( https://forum.nasaspaceflight.com/index.php?topic=39004.msg1484568#msg1484568 that followed this message: https://forum.nasaspaceflight.com/index.php?topic=39004.msg1483411#msg1483411 ) regarding calculations of TheTraveller's test, I attach below:
1) The previously shown electric field norm (in Decibel logarithmic scale) contour plot calculated using FEKO Boundary Element Method by IslandPlaya (@ Reddit), correctly identified by SeeShells as mode shape TE013
vs.
2) the electric field norm (in Decibel logarithmic scale) contour plot calculated using the exact solution I obtained using Wolfram Mathematica, for mode shape TE013
Notice that the exact solution picture is upside down from the FEKO image, because the exact solution vertical scale is in terms of the distance to the apex of the cone, with the apex of the cone being at the bottom.
The image comparison below verifies the agreement between FEKO and the exact solution obtained with Wolfram Mathematica for TheTraveller's test, and it verifies that indeed SeeShells identified the correct mode shape as TE013 (since in the exact solution there is no doubt as to what the mode shape is, because one sets the m,n,p parameters as input in the solution functions for the exact solution, while in numerical analysis like FEKO, the mode shape has to be identified visually). I had to write a few words of code to get the results in the Decibel scale used by FEKO by default, in order to compare. I find it strange that FEKOdefaultstoshows a logarithmic scale, because I don't find such a nonlinear scale useful for a linear problem, since it artificially places less contours at high magnitude and more contours at low magnitude, hence distorting the physical meaning, in my view. In my view it is better to use a linear scale when outputting the results for a linear problem (this problem is linear because it is a solution to Maxwell's equations, which are linear, and the constitutive equations used are also linear).
__________________________________________
EDIT: IslandPlaya just reported an excellent explanation for the reason that a logarithmic scale is used instead of a linear scale.Quote from: IslandPlayaFeko defaults to linear.
The problem is the scale (min and max) of the fields measured across the whole freq range of the movie and the sharpness of the resonance peaks.
When I choose a linear scale 99% of the movies were coloured blue (the lowest values) with just a few frames 'blipping in' with orange and red. Boring.
So I chose the log scale just so the visualisation was better and more useful.
For doing single freqs. or a narrower range I would choose a linear scale as it eases measurement and comparison.
There was a lot more thought and work went into this sim run and post-processing than may be apparent at first.
If there is a better way to do movie visualisations wrt to scaling of values then please let me know.
What the experience of doing the movies with a linear scale taught me is that the resonance peaks are incredibly narrow in the simulation with fields strengths otherwise being close to zero.
If this is reflected in the real world then it will be a real engineering challenge to first find and then track the chosen resonance freq.
So the reason is because he is displaying not just a single mode, but he is scanning resonances for a whole range of modes from 1.9GHz to 2.9 GHz, spanning a very large range of electric field strengths for different modes (with some dominant modes, having much larger electric field strengths than other, non-dominant modes). A logarithmic scale enables him to clearly show all the resonant modes, because a logarithmic scale over-emphasizes the low-value contours and under-emphasizes the high-value contours. (And this also enabled SeeShells to find TE013 which otherwise would have been hard to find.)
Note:
it is known in the literature that the mode that TheTraveller wants to excite TE013 is a non-dominant mode, all TE01p modes are not dominant: they are difficult to excite. They are high Q, hence narrow bandwidth, and need to be excited by carefully placing current loops at the optimal locations.Quote from: Collin Foundations for Microwave Engineering, page 506Of particular interest is the TE011 mode for wavemeters because its Q is 2 to 3 times that of the TE111 mode. Another advantage of the TE011 mode is that there are no axial currents. This means that the end plate of the cavity can be free to move to adjust the cavity length for tuning purposes without introducing purposes without introducing any significant loss since no currents flow across the gap between the circular end plate and the cylinder wall is parallel to the current flow lines. However the TE011 mode is not the dominant mode: so care must be exercised to choose a coupling scheme that does not excite the other possible modes that could resonate within the frequency tuning range of the cavity
A dominant mode is the mode which explains the largest part of a system's response to an impulse (where the overall system response is obtained from modal mixing or summation of modes). It can also be defined as the mode at which the spectral response contains the maximal spectral power.
When several mode shapes are excited by a wide-spectrum excitation (for example by a magnetron) the more dominant modes participating in the excitation will have a greater participation factor in the total response.
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#2390 by Notsosureofit on 30 Jan, 2016 01:36
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Please notice that:
In other words, Minotti writes that the theory used in Minotti's paper is in conflict already with our experimental knowledge of the magnetic field around the Earth, so we already know that the theory discussed in the paper cannot be a good model of reality.
Still, Minotti's mathematical analysis is good and useful, as he obtains an exact solution for resonance of the EM Drive under Maxwell's equations which is even more elegant than Greg Egan's solution. Dr. Frasca (NSF user StrongGR) used Minotti's paper as one of his references for his paper on the EM Drive that we discussed in previous threads:
Einstein-Maxwell equations for asymmetric resonant cavities
Marco Frasca
http://arxiv.org/abs/1505.06917v1
Speaking of Frasca's paper, I've stared at it long enough to convince myself that his calculation is probably correct, but that it is of the second order. That is to say what he has calculated is the asymmetric contribution from the electromagnetic force on the walls of the cavity as distorted by the gravitational dispersion induced into the cavity. It is not the force of the photon dispersion itself.
I really should try to do the dispersion calculation from Minotti's cavity solution one of these days.
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#2391 by Rodal on 30 Jan, 2016 01:47
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Please notice that:
In other words, Minotti writes that the theory used in Minotti's paper is in conflict already with our experimental knowledge of the magnetic field around the Earth, so we already know that the theory discussed in the paper cannot be a good model of reality.
Still, Minotti's mathematical analysis is good and useful, as he obtains an exact solution for resonance of the EM Drive under Maxwell's equations which is even more elegant than Greg Egan's solution. Dr. Frasca (NSF user StrongGR) used Minotti's paper as one of his references for his paper on the EM Drive that we discussed in previous threads:
Einstein-Maxwell equations for asymmetric resonant cavities
Marco Frasca
http://arxiv.org/abs/1505.06917v1
Speaking of Frasca's paper, I've stared at it long enough to convince myself that his calculation is probably correct, but that it is of the second order. That is to say what he has calculated is the asymmetric contribution from the electromagnetic force on the walls of the cavity as distorted by the gravitational dispersion induced into the cavity. It is not the force of the photon dispersion itself.
I really should try to do the dispersion calculation from Minotti's cavity solution one of these days.
You definitely should do this, and sooner rather than later
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#2392 by SteveD on 30 Jan, 2016 01:51
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TheTRAVELLER's test: CONTOUR PLOTS COMPARISON OF norm of ELECTRIC FIELD in Decibel scale, EXACT SOLUTION vs. FEKO (Boundary Element Method) model
Continuing the discussion from this message ( https://forum.nasaspaceflight.com/index.php?topic=39004.msg1484568#msg1484568 that followed this message: https://forum.nasaspaceflight.com/index.php?topic=39004.msg1483411#msg1483411 ) regarding calculations of TheTraveller's test, I attach below:
1) The previously shown electric field norm (in Decibel logarithmic scale) contour plot calculated using FEKO Boundary Element Method by IslandPlaya (@ Reddit), correctly identified by SeeShells as mode shape TE013
Nice. Two questions (more proforma than anything else).
1. Any evidence of one or more small areas of extreme energy density (especially around the end plates)? Can this simulation offer an explanation for the observed end plate warping at low levels of rf power?
2. Do each of the lobes contain an equal amount of energy? If not, can you identify which have more or less energy? -
#2393 by Rodal on 30 Jan, 2016 02:03
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TheTRAVELLER's test: CONTOUR PLOTS COMPARISON OF norm of ELECTRIC FIELD in Decibel scale, EXACT SOLUTION vs. FEKO (Boundary Element Method) model
Continuing the discussion from this message ( https://forum.nasaspaceflight.com/index.php?topic=39004.msg1484568#msg1484568 that followed this message: https://forum.nasaspaceflight.com/index.php?topic=39004.msg1483411#msg1483411 ) regarding calculations of TheTraveller's test, I attach below:
1) The previously shown electric field norm (in Decibel logarithmic scale) contour plot calculated using FEKO Boundary Element Method by IslandPlaya (@ Reddit), correctly identified by SeeShells as mode shape TE013
Nice. Two questions (more proforma than anything else).
1. Any evidence of one or more small areas of extreme energy density (especially around the end plates)? Can this simulation offer an explanation for the observed end plate warping at low levels of rf power?
2. Do each of the lobes contain an equal amount of energy? If not, can you identify which have more or less energy?
1) I have not plotted the energy density. Sounds like a very good idea
. Will need to find a little time to write a little code to do it.
2) So far I have shown the a) Magnetic Vector Field, b) the Poynting vector field and c) the Electric vector resultant (magnitude of the vector) in a logarithmic scale to compare with FEKO. I can also readily show plots of the Maxwell stress distribution and different electromagnetic field components in different directions.
3) Maybe some of the readers know of some standard textbook or paper that has the energy density distribution plots? I will look for one to compare with my future calculation...
4) Maybe IslandPlaya, if he reads this, can also use FEKO to plot the energy density (if FEKO has that as an option ? )
5) Warping of the end plates. It could be due to Thermal Buckling of the end plate: due to induction heating of the end plate. Or it could be due to misalignment, consolidation of TheTraveller's frustum which he says is "held only by gravity" as he quickly put it together to get some preliminary results. -
#2394 by rfmwguy on 30 Jan, 2016 15:17
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There are many of us who are often discouraged by doors that appear to close on possible theories for the emdrive effect, for we know it should not work. For those who remain open-minded, I found a list of unresolved problems in physics:
https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics
The Quantum Gravity section has a couple of entries that could relate to the emdrive.
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#2395 by SeeShells on 30 Jan, 2016 15:38
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There are many of us who are often discouraged by doors that appear to close on possible theories for the emdrive effect, for we know it should not work. For those who remain open-minded, I found a list of unresolved problems in physics:
https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics
The Quantum Gravity section has a couple of entries that could relate to the emdrive.
The fat lady has not belted out her song yet. A good researcher must leave all the doors open including Foobie Dust. Mother Nature has taken us by surprise more than once over the years. If we had EM theory down pat and forget the EMDrive we would have had Mr. Fusion a long time ago. There is still much to learn and know and discover. I try to at least to keep my sanity by putting all the theories on a sliding scale, Foobie Dust is around .1% but the door isn't closed.
Shell -
#2396 by rfmwguy on 30 Jan, 2016 16:05
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I think our old friend Delta Mass would correct you by saying Floobie Dust.There are many of us who are often discouraged by doors that appear to close on possible theories for the emdrive effect, for we know it should not work. For those who remain open-minded, I found a list of unresolved problems in physics:
https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics
The Quantum Gravity section has a couple of entries that could relate to the emdrive.
The fat lady has not belted out her song yet. A good researcher must leave all the doors open including Foobie Dust. Mother Nature has taken us by surprise more than once over the years. If we had EM theory down pat and forget the EMDrive we would have had Mr. Fusion a long time ago. There is still much to learn and know and discover. I try to at least to keep my sanity by putting all the theories on a sliding scale, Foobie Dust is around .1% but the door isn't closed.
Shell
The philosophy/psychology of physics has been a real eye-opener for me. The uncertainties are many, but if you read position statements on the emdrive, you'd never believe there were any possibilities. (Worse yet, its been made into a parody by those who haven't resolved just one of the above physics problems themselves.)
So...we march on...for what reason, I have no idea
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#2397 by SeeShells on 30 Jan, 2016 16:26
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Foobie is my take on Floopie (always hated Floopie). If he has issues with my take he can come back and explain why. He is missed.
I think our old friend Delta Mass would correct you by saying Floobie Dust.There are many of us who are often discouraged by doors that appear to close on possible theories for the emdrive effect, for we know it should not work. For those who remain open-minded, I found a list of unresolved problems in physics:
https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics
The Quantum Gravity section has a couple of entries that could relate to the emdrive.
The fat lady has not belted out her song yet. A good researcher must leave all the doors open including Foobie Dust. Mother Nature has taken us by surprise more than once over the years. If we had EM theory down pat and forget the EMDrive we would have had Mr. Fusion a long time ago. There is still much to learn and know and discover. I try to at least to keep my sanity by putting all the theories on a sliding scale, Foobie Dust is around .1% but the door isn't closed.
Shell
The philosophy/psychology of physics has been a real eye-opener for me. The uncertainties are many, but if you read position statements on the emdrive, you'd never believe there were any possibilities. (Worse yet, its been made into a parody by those who haven't resolved just one of the above physics problems themselves.)
So...we march on...for what reason, I have no idea
I do it because I can. I do it because it has been said you can't do it. I do it because there might be a small chance that it will help our children see a universe without bounds. I do it because someone has to step up to the plate and try. I do it because I made a promise to my mother who passed last year that I'd do my best.
I remember when I was told there are no women engineers and I was foolish to become one. That only made me more determined to prove them wrong. How dare they tarnish a dream.
I'll set in this eye of the hurricane of EMDrive speculation taking a little calculated well thought out steps at a time to make it happen, knowing I'll do my best and keep a promise.
Shell -
#2398 by Rodal on 30 Jan, 2016 17:13
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Although, admittedly, going by memory is treacherous, as I happily admit imperfect memoryThanks for your info Zen...glad to see you back. Not sure if I read your post the first time and was not aware there was a counter-point to it...but my memory is Rodal/10x106
I would give it 0%. My understanding of their protocol is as follows:
If you were going to put an estimate on it, what percentage would you give that it is not space-time distortion?
(1) Align the interferometer so there is no fringe at the detector.
(2) Energize the capacitor device and acquire an image of the interference pattern.
The White-Juday interferometer does not have a moving mirror so it can't measure the phase shift in realtime. Besides this, the experiment was not done in a vacuum or controlled atmosphere and there was no differential test. By differential test I mean measuring the same interferogram with no RF energy and using that as a reference. The W-J interferometer is not a very precise optical instrument. When I was working for the FTIR company we would use a narrow-band Neon source (a frosted-glass light box with a large Neon bulb in it) to roughly align the interferometer with the moving mirror stopped. After only 1 or 2 fringes covered the 3" Dia. optical path we could align the fixed mirror for maximum interferogram amplitude with a broadband IR source. That was always very tricky because the interferogram's S/N would climb by several orders of magnitude. Only then could you acquire spectra. This is where they would have to be to convince me there was any EM effect being seen. But their instrument does not have the required stability and a camera is not fast enough. With a stable instrument they could collect a sample with no EM in it and then ratio it with one that has the EM capacitor field or whatever it is they sampled. If there is a phase shift it will show up. This could be done with a narrow band source just as well. The interferogram would just be a narrow spike. Below is a typical broadband IR interferogram from an FTIR spectrometer. When an FFT is done on this signal an audio frequency signal that is the passband spectra is produced. For a narrow-band source the only useful information would be the phase shift. One of the instruments we sold was a film thickness guage. It measured the thickness of films deposited on Silicon wafers by measuring the phase shift between the interference patterns reflected from each interface. While those interferometers were less precise and had a smaller aperture, they used a moving mirror. DC drift, heat, and many other factors conspire against optical measurement techniques that don't use differential methods.
Here is a paper on narrow band spectroscopy with FTIR-
http://link.springer.com/chapter/10.1007%2F978-1-4614-7804-1_18#page-1 (*), this is my recollection of NASA Eagleworks interferometer tests :
1) The reported results of the warp-field interferometer tests were conducted in-ambient conditions, not in a vacuum. (In this, our memories agree).
2) Half of the data samples were taken in the un-energized state (no DC field across the cap-ring and no Radio Frequency excitation of the resonant cavity) and the other half taken in the energized state being produced by either of the following methods (both methods were studied):
a) a large dc E-field with many kV across the cap-ring,
or
b) a cylindrical resonant cavity resonating resonating with mode shape TM010 at ~1.5 GHz with a loaded Q-factor of ~2,500 being driven with ~30 Watts of RF power.
So, if you are willing to consider that running half of the samples in an un-energized condition constitutes a differential test, then our memories are different, since I recall that NASA run half of the samples in an un-energized condition.
3) Before we (unfortunately) stopped getting updates from Paul March I seem to recall that their attempts at running in vacuum were running into problems of glow discharge, which to me sound like the same multipactor effect that has plagued particle accelerator resonant cavities in vacuum ever since the 1940s (as famously reported by Nobel Prize winner Luis Alvarez, for example) and that have plagued resonant cavity and waveguides operating in space since the 1960's.
4) I hope that Paul March will be allowed to come back, clarify the record (concerning different recollections on whether NASA run or did not run sample runs without energizing) and will update us as to NASA's efforts to run the experiment in vacuum and overcome the multipaction problems.
5) Dr. Marco Frasca (NSF user StrongGR) was also very interested in these interferometer tests, perhaps he can also give us his recollection
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(*) Imperfect memory can be a blessing, sometimes
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#2399 by X_RaY on 30 Jan, 2016 19:01
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Stupid question:
Have someone think about of some kinetic response while heating up the antenna in the first few ms? During the first milliseconds after RF injection the antenna itself acts as a heat sink and causes a divergence of energy applied to the cavitý. Of course this would be a sort of pulse response only.
The back reaction to this energy displacement could cause a kinetic response.. May be this is of the order of 10^-xx.
I am not sure about the relevance at the moment but it came into my mind and I don't wanna withheld this thought
. Will need to find a little time to write a little code to do it.