-
#2320 by Rodal on 13 May, 2016 13:58
-
... If different Abraham/Minkowski formulae apply in different circumstances then the forces would be different, especially as, as you remark, n^2 appears to be of the order of 10^8....
Correction: it is your formula (not me!) that gives n=14651, and hence your formula gives n^2 of the order of 10^8, 215 million times higher than vacuum, which is absurdly high. My remark was that on the contrary, I showed why your formula, as well as your value for n does not make sense for this problem.
Bottom line: your formula for n is not applicable, because you assume a plane wave travelling through space and you cannot have a plane wave travelling through the skin depth of copper: it cannot satisfy the boundary conditions of the problem which are that the electric field parallel to the surface of copper should be close to zero, and that the magnetic field should decay exponentially within 1 micrometer of copper. -
#2321 by RERT on 13 May, 2016 14:00
-
There seems to be a mood to suggest that only tests with batteries and with torsional pendulums are valid.
I don't believe this is a scientific position. The only thing which matters is the measured force and its error bars. I'm in-line with the poster who suggested that if I can move a supertanker, he could forgive the piece of string attached to my finger.
To date I don't recall seeing (I confess I read quickly) any scale estimates as to the errors introduced by using cabled power. Making an assertion that only battery driven tests are credible is, in that context, not science. It just smacks of cueing up an excuse to dismiss potentially positive results.
Please prove me wrong, and tell us what size of error might be created by importing mains power to a test rig.
R. -
#2322 by rfmwguy on 13 May, 2016 14:05
-
There seems to be a mood to suggest that only tests with batteries and with torsional pendulums are valid.
I am of the same belief (perhaps a minority here). The good news is the umbilical attachment to the beam is technically at a single point. This helps. I will have an IR temp probe at this juncture to monitor any heat rise. This point is about 5 feet from both the power supply and the magnetron.
I don't believe this is a scientific position. The only thing which matters is the measured force and its error bars. I'm in-line with the poster who suggested that if I can move a supertanker, he could forgive the piece of string attached to my finger.
To date I don't recall seeing (I confess I read quickly) any scale estimates as to the errors introduced by using cabled power. Making an assertion that only battery driven tests are credible is, in that context, not science. It just smacks of cueing up an excuse to dismiss potentially positive results.
Please prove me wrong, and tell us what size of error might be created by importing mains power to a test rig.
R. -
#2323 by RERT on 13 May, 2016 14:13
-
The formula comes from solving the Wave equation in the medium:
∂²A/∂x²-με∂²A/∂t²-μσ∂A/∂t=0
where A is either E or B. I solved this myself, and cross checked against some undergraduate lecture notes in Electromagnetism from Liverpool university available on the web. It's not my formula.
Your condition on B is not a boundary condition, it is an observation on the solution. In any case, the formula gives standard skin depths. I don't see any reason to believe that the incident, reflected and transmitted waves cannot meet the condition on E.
R.
-
#2324 by Rodal on 13 May, 2016 14:18
-
The formula comes from solving the Wave equation in the medium:
That's wrong, as I showed (http://forum.nasaspaceflight.com/index.php?topic=39214.msg1529920#msg1529920) no single travelling wave can meet the boundary conditions of the problem, a well known-fact. To meet the boundary conditions one needs counter-propagating waves: a standing wave. Standing waves, as shown in all of the COMSOL and FEKO runs.
∂²A/∂x²-με∂²A/∂t²-μσ∂A/∂t=0
where A is either E or B. I solved this myself, and cross checked against some undergraduate lecture notes in Electromagnetism from Liverpool university available on the web. It's not my formula.
Your condition on B is not a boundary condition, it is an observation on the solution. In any case, the formula gives standard skin depths. I don't see any reason to believe that the incident, reflected and transmitted waves cannot meet the condition on E.
R.
However, if you think that makes sense, you could have aero run your value of the real part of the electric permittivity 215 million times higher than what he is presently running in Meep runs, and explore its consequences.
Please show us what are the consequences on the electromagnetic fields and the quality factor of resonance if one uses a relative value of real part of the relative electric permittivity 215 million times higher than the value established by user DeltaMass in these threads long ago and that aero has been running in Meep. (For reference: DeltaMass is also from the UK (Oxford University) and had a background in modelling the behavior of metals, the copper material model that has been used in Meep by aero, and shown by SeeShells, uses a real part of εr=1 for copper)
This would advance the discourse, rather than continuing stating your beliefs.
This would be of value to DIY like SeeShells that have been showing Meep runs (and relying on them to some extent), as aero has been running the DeltaMass model.
Your formula states that the Meep models that aero has been running and that SeeShells has been showing are extremely wrong: off by a huge factor of 215 million times in the value of the real part of the relative electric permittivity.
Wow! 215 million times, that is a huge difference, affecting the Meep runs that aero and SeeShells have been showing, runs like this one, that were run using εr=1 for copper, while you propose that it should be run with εr=2.15*108 instead:
-
#2325 by RERT on 13 May, 2016 16:13
-
Equations are not beliefs. I note that you did not challenge the equation or its solution.
I'm not trying to solve the frustrum, I'm trying to estimate the velocity of light in a copper conductor. I did the obvious analysis, which turns out to be validated by standard texts. These state that the wavelength at a given frequency is dramatically smaller in a conductor, i.e. the speed of light is much slower. I think that's also intuitive.
Just post your view of the speed of light in copper at 2.45 Ghz with a reference, and I will follow it up. That is what we are debating.
R. -
#2326 by Rodal on 13 May, 2016 16:19
-
Equations are not beliefs. I note that you did not challenge the equation or its solution.
I already showed that you are incorrectly solving Maxwell's equations because your incorrect solution:
I'm not trying to solve the frustrum, I'm trying to estimate the velocity of light in a copper conductor. I did the obvious analysis, which turns out to be validated by standard texts. These state that the wavelength at a given frequency is dramatically smaller in a conductor, i.e. the speed of light is much slower. I think that's also intuitive.
....
R.
1) does not satisfy the boundary conditions of the electromagnetic fields at the copper interface
2) you cannot have an infinite plane wave in a frustum of a cone. For a truncated cone with spherical ends, the solutions are spherical waves, instead of plane waves
3) in your solution you have the electric and magnetic fields completely in phase with each other. The wave solutions for a truncated cone do not have the fields in phase with each other.
Valid solutions to partial differential equations (like Maxwell's equations) must satisfy the boundary conditions of the physical problem.
Thus your "solution" is not applicable to EM Drive Developments - related to space flight applications, as you are now recognizing that you areQuote from: Rertnot trying to solve the frustrum
Rather than continuing to debate your incorrect solution and consequences, and since the Moderator of this thread has asked that people should be helpful to DIY builders, please be helfpful to DIY builders by addressing the fact that what you are proposing is that the model by DeltaMass is off by a huge factor of 215 million times and that the Meep runs by aero are completely wrong, as you state that the real part of the electric permittivity in copper should be 215 million times greater than what aero has been running and SeeShells has been showing.
That would be useful to this thread.
-
#2327 by Gilbertdrive on 13 May, 2016 16:29
-
There seems to be a mood to suggest that only tests with batteries and with torsional pendulums are valid.
I don't believe this is a scientific position. The only thing which matters is the measured force and its error bars. I'm in-line with the poster who suggested that if I can move a supertanker, he could forgive the piece of string attached to my finger.
To date I don't recall seeing (I confess I read quickly) any scale estimates as to the errors introduced by using cabled power. Making an assertion that only battery driven tests are credible is, in that context, not science. It just smacks of cueing up an excuse to dismiss potentially positive results.
Please prove me wrong, and tell us what size of error might be created by importing mains power to a test rig.
R.
I can not speak for others, but I have to precise that when I suggest that only tests with batteries and with torsional pendulums are valid as proof of the emdrive, it is implied that it is with the actual millinewtons thrust. If there is a test where a superconducting emdrive build lifts from the ground, even if there is a wire going to a stationary power supply, it is a different case.
As it was already written, it should be to the people using external power to proove that the thrust is not due to momentum carried by the cable.
But, anyway, I can answer to your question.
The new Pr Yang setup, described in her 2016 peer-reviewed paper, with the external power and the bias of the heating wire, gave a force or 8-10mN. If I use the table on the wiki, the power was 220W, it means around 45mN/Kw.
So, The Pr Yang Experiment is a proof that the cable artifact can give at least 45mN/Kw
Any experiment that does not take any care of the cable, and is giving less than 45 mN/Kw is a proof of nothing.
But there are ways to take the cable into account.
Also, I can understand the 2 following proofs.
1 : If an emdrive is put out of resonance, like in Stansell experiment. The magnetron works the same way. The AC wire itself should not see an internal difference, it should product the same thermal and internal magnetic effects that with the resonating Emdrive.
I do not tell that it is a definitive proof, but it eliminates at least the Pr Yang thermal coax artifact.
2 : The Reversion of the thrust by reverting the frustrum. The Magnetron should still be at the same position, with the wire unchanged, but only the frustrum reverted. The RF feed cable has to be moved, and make an angle but it is not an issue since this cable in entirely on the build.
Here also, the AC Wire cable should not see the difference. It should heat the same, it should get the same magnetic field inside.
The remaining issue that I see in both cases is the external magnetic field outside of the coax. As it was written earlier, the coax is not perfect, so, pratically, there will be some magnetic field escaping outside.
This magnetic field could make a difference following the position of the frustrum, and maybe following if the frustrum is at resonnance or not.
It should be possible to mesure the magnetic field out of the coax, and to calculate the maximum interaction with the build itself. If it is several orders of magnitude lower than the thrust, I think it start to be a strong proof that the thrust is not from the coax cable. -
#2328 by rfmwguy on 13 May, 2016 16:50
-
Lets back up here since I've not followed this too closely being in test stand redesign, setup, etc.,There seems to be a mood to suggest that only tests with batteries and with torsional pendulums are valid.
I don't believe this is a scientific position. The only thing which matters is the measured force and its error bars. I'm in-line with the poster who suggested that if I can move a supertanker, he could forgive the piece of string attached to my finger.
To date I don't recall seeing (I confess I read quickly) any scale estimates as to the errors introduced by using cabled power. Making an assertion that only battery driven tests are credible is, in that context, not science. It just smacks of cueing up an excuse to dismiss potentially positive results.
Please prove me wrong, and tell us what size of error might be created by importing mains power to a test rig.
R.
I can not speak for others, but I have to precise that when I suggest that only tests with batteries and with torsional pendulums are valid as proof of the emdrive, it is implied that it is with the actual millinewtons thrust. If there is a test where a superconducting emdrive build lifts from the ground, even if there is a wire going to a stationary power supply, it is a different case.
As it was already written, it should be to the people using external power to proove that the thrust is not due to momentum carried by the cable.
But, anyway, I can answer to your question.
The new Pr Yang setup, described in her 2016 peer-reviewed paper, with the external power and the bias of the heating wire, gave a force or 8-10mN. If I use the table on the wiki, the power was 220W, it means around 45mN/Kw.
So, The Pr Yang Experiment is a proof that the cable artifact can give at least 45mN/Kw
Any experiment that does not take any care of the cable, and is giving less than 45 mN/Kw is a proof of nothing.
But there are ways to take the cable into account.
Also, I can understand the 2 following proofs.
1 : If an emdrive is put out of resonance, like in Stansell experiment. The magnetron works the same way. The AC wire itself should not see an internal difference, it should product the same thermal and internal magnetic effects that with the resonating Emdrive.
I do not tell that it is a definitive proof, but it eliminates at least the Pr Yang thermal coax artifact.
2 : The Reversion of the thrust by reverting the frustrum. The Magnetron should still be at the same position, with the wire unchanged, but only the frustrum reverted. The RF feed cable has to be moved, and make an angle but it is not an issue since this cable in entirely on the build.
Here also, the AC Wire cable should not see the difference. It should heat the same, it should get the same magnetic field inside.
The remaining issue that I see in both cases is the external magnetic field outside of the coax. As it was written earlier, the coax is not perfect, so, pratically, there will be some magnetic field escaping outside.
This magnetic field could make a difference following the position of the frustrum, and maybe following if the frustrum is at resonnance or not.
It should be possible to mesure the magnetic field out of the coax, and to calculate the maximum interaction with the build itself. If it is several orders of magnitude lower than the thrust, I think it start to be a strong proof that the thrust is not from the coax cable.
Exactly what hypothesis is being presented to our readership here?
Are we stating the DC/AC/RF energy transmitted through wires are producing a kinetic momentum outside of Lorentz force and thermal expansion or contraction? Continuous or instantaneous?
If this is the case, my humble suggestion is to write up a brief that CLEARLY states that position with theory and numbers that back it up. Comments here, there and every few pages aren't going to convince anyone, especially me that this hypothesis has any merit.
Typical umbilical connections:
RF is 2.45 GHz consider power to be 750 watts
or
DC is 4 kV at about 0.3 mA pulsed at 60 hz plus (temporary, 1-2 sec heater) voltage of 3 V at about 10 A
Pick a standard coax (similar to RG-8) or wire gauge such as 14
Tell us what kinetic force is presented outside of Lorentz or thermal buckling
In effect, I am challenging those who propose an error source to do what builders have to do...present their case. If this cannot be done, I humbly suggest we not keep re-hashing this topic. Its interesting, for sure, but somebody needs to present it clearly and concisely. -
#2329 by rfmwguy on 13 May, 2016 17:00
-
Thanks to Phil in Australia who found Paul Stansell's public science report he used with his ISEF science experiment. It is attached below.
-
#2330 by X_RaY on 13 May, 2016 17:21
-
The formula comes from solving the Wave equation in the medium:
That's wrong, as I showed (http://forum.nasaspaceflight.com/index.php?topic=39214.msg1529920#msg1529920) no single travelling wave can meet the boundary conditions of the problem, a well known-fact. To meet the boundary conditions one needs counter-propagating waves: a standing wave. Standing waves, as shown in all of the COMSOL and FEKO runs.
∂²A/∂x²-με∂²A/∂t²-μσ∂A/∂t=0
where A is either E or B. I solved this myself, and cross checked against some undergraduate lecture notes in Electromagnetism from Liverpool university available on the web. It's not my formula.
Your condition on B is not a boundary condition, it is an observation on the solution. In any case, the formula gives standard skin depths. I don't see any reason to believe that the incident, reflected and transmitted waves cannot meet the condition on E.
R.
However, if you think that makes sense, you could have aero run your value of the real part of the electric permittivity 215 million times higher than what he is presently running in Meep runs, and explore its consequences.
Please show us what are the consequences on the electromagnetic fields and the quality factor of resonance if one uses a relative value of real part of the relative electric permittivity 215 million times higher than the value established by user DeltaMass in these threads long ago and that aero has been running in Meep. (For reference: DeltaMass is also from the UK (Oxford University) and had a background in modelling the behavior of metals, the copper material model that has been used in Meep by aero, and shown by SeeShells, uses a real part of εr=1 for copper)
This would advance the discourse, rather than continuing stating your beliefs.
This would be of value to DIY like SeeShells that have been showing Meep runs (and relying on them to some extent), as aero has been running the DeltaMass model.
Your formula states that the Meep models that aero has been running and that SeeShells has been showing are extremely wrong: off by a huge factor of 215 million times in the value of the real part of the relative electric permittivity.
Wow! 215 million times, that is a huge difference, affecting the Meep runs that aero and SeeShells have been showing, runs like this one, that were run using εr=1 for copper, while you propose that it should be run with εr=2.15*108 instead:
-
#2331 by Rodal on 13 May, 2016 17:43
-
...
I expect that if you run with a finite value of tan δ, the value of the real part of the electric permittivity then becomes irrelevant, no matter how high since what matters is tan δ =ε "/ε', as shown by Mansuripur (in the reference I gave previous). Is that correct?
So we can set,
ε' =108 with ε " =ε' tan δ
or
ε' =1 with ε " =ε' tan δ
Same thing.
Point being that what characterizes conductors like copper is a large value of tan δ -
#2332 by X_RaY on 13 May, 2016 17:47
-
I also tried the dielectric conditions below. There is almost NO difference as expected.
...
I expect that if you run with a finite value of tandelta, the value of the real part of the electric permittivity then becomes irrelevant, no matter how high since what matters is tan δ =ε "/ε', as shown by Mansuripur (in the reference I gave previous). Is that correct?
Even if i use tanδ =1000 and this huge epsilon there is no resonance at least in the frequency range of
2GHz ot 3GHz(while using conductive surfaces there are several).
The only thing is the Q drops down. Using normalized field strength look equal to the .gif above.
-
#2333 by Rodal on 13 May, 2016 17:49
-
To get a correct value of quality factor (Q) I expect that you have to use a higher value of tan δ. is that correct?
I also tried the dielectric conditions below. There is almost NO difference as expected.
...
I expect that if you run with a finite value of tandelta, the value of the real part of the electric permittivity then becomes irrelevant, no matter how high since what matters is tan δ =ε "/ε', as shown by Mansuripur (in the reference I gave previous). Is that correct?
Microwave frequencies are much lower than the plasma frequency for copper (2620 TeraHertz)
Hence:
* real part of relative electric permittivity closer to 1
* very high value of imaginary part of electric permittivity --> ∞
* tan δ ---> ∞
-
#2334 by SeeShells on 13 May, 2016 17:54
-
I want to inject a little info here about modeling a perfect conductor instead of the drude model of copper. Aero ran one of my designs as a perfect conductor instead of the drude and posted to me a Q >11,000,000,000 yes that's billion. No matter how it made my heart skip a beat I knew it was wrong. We ended up redoing with a drude copper model with a Q around 88k, which was better.Equations are not beliefs. I note that you did not challenge the equation or its solution.
I already showed that you are incorrectly solving Maxwell's equations because your incorrect solution:
I'm not trying to solve the frustrum, I'm trying to estimate the velocity of light in a copper conductor. I did the obvious analysis, which turns out to be validated by standard texts. These state that the wavelength at a given frequency is dramatically smaller in a conductor, i.e. the speed of light is much slower. I think that's also intuitive.
....
R.
1) does not satisfy the boundary conditions of the electromagnetic fields at the copper interface
2) you cannot have an infinite plane wave in a frustum of a cone. For a truncated cone with spherical ends, the solutions are spherical waves, instead of plane waves
3) in your solution you have the electric and magnetic fields completely in phase with each other. The wave solutions for a truncated cone do not have the fields in phase with each other.
Valid solutions to partial differential equations (like Maxwell's equations) must satisfy the boundary conditions of the physical problem.
Thus your "solution" is not applicable to EM Drive Developments - related to space flight applications, as you are now recognizing that you areQuote from: Rertnot trying to solve the frustrum
Rather than continuing to debate your incorrect solution and consequences, and since the Moderator of this thread has asked that people should be helpful to DIY builders, please be helfpful to DIY builders by addressing the fact that what you are proposing is that the model by DeltaMass is off by a huge factor of 215 million times and that the Meep runs by aero are completely wrong, as you state that the real part of the electric permittivity in copper should be 215 million times greater than what aero has been running and SeeShells has been showing.
That would be useful to this thread.
Very busy day, great to see all the good debates.
Shell -
#2335 by Rodal on 13 May, 2016 18:31
-
[...
I want to inject a little info here about modeling a perfect conductor instead of the drude model of copper. Aero ran one of my designs as a perfect conductor instead of the drude and posted to me a Q >11,000,000,000 yes that's billion. No matter how it made my heart skip a beat I knew it was wrong. We ended up redoing with a drude copper model with a Q around 88k, which was better.
Very busy day, great to see all the good debates.
Shell
Yes, at microwave frequencies, (microwave frequency of 2.45 109 Hz is 1 million times smaller than plasma frequency for copper is 2.62 1015 Hz ) real part of electric permittivity in Drude model is close to 1, as it was modeled by DeltaMass. Not 250 million.
Slide from Dr. Raymond Rumpf Lecture
http://emlab.utep.edu/ee5390em21/Lecture%202%20--%20Lorentz%20and%20Drude%20models.pdf
This formula for n in the slide:
n=(1+j)√(σo/(2ω))
using
ω=2 Pi 2.45*10^9 Hz = 1.539*10^10 Hz
σ=5.85x10^7 (questionable what value to use for Drude DC conductivity (σo, here we use typical DC conductivity)
gives
n=(1+j)√(5.85x10^7 /(2*1.539*10^10 Hz))
= (1+j) 0.0436
so, instead of a high value of n~14500 it gives a very low value of n, lower than the value of 1 by a factor of 23 times, which is much better than being larger by a factor of 14500 times . At zero frequency, n goes to Infinity. Since n in this formula is so frequency dependent, I rather go with εr~1 value to evaluate Abraham Mynkowski difference, since the Drude model estimate for εr~1 is independent of frequency.
Also, because I have read the original papers of both Abraham and Minkowski, and neither of them formulate their expressions in terms of the coefficient of refraction, instead they do it in terms of the electric permittivity and the magnetic permeability. Expressing this in term of the index of refraction n involves assuming a relation between n and those material properties, that one is better off avoiding.
////////////////////////////////////////
Concerning Abraham/Minkowski controversy for air/copper or vacuum/copper, see:
Whence the Minkowski Momentum?
Masud Mansuripur† and Armis R. Zakharian‡
Optics Communications 283, 3557-3563 (2010)]
http://arxiv.org/abs/1207.6676
shows that what matters for the Abraham Minkowski controversy is the imaginary part of refractive index of metal, and that the momentum transferred is completely due to the medium inside the cavity (air or vacuum) and not influenced by the metal properties.
Need a dielectric instead of a good conductor to show significant Abraham Minkowski difference for electric field at microwave frequencies. Otherwise need significant difference in magnetic permeability for magnetic field, a magnetic ferrite with μr > 1 instead of copper which has μr ~ 1 similar to vacuum and air.
-
#2336 by FattyLumpkin on 13 May, 2016 20:00
-
Dr. Rodal, could you take a moment out of the current discussion and comment on the Sonny White video specifically re TRL2 to TRL 3, and the sustained 20 Newtons/kilowatt reported. Sonny also stated that EWL had or was in the process of manufacturing and sending their test articles out to other institutions for independent evaluation. Thnx FL
-
#2337 by Rodal on 13 May, 2016 20:09
-
Dr. Rodal, could you take a moment out of the current discussion and comment on the Sonny White video specifically re TRL2 to TRL 3, and the sustained 20 Newtons/kilowatt reported. Sonny also stated that EWL had or was in the process of manufacturing and sending their test articles out to other institutions for independent evaluation. Thnx FL
The video in YouTube was posted in ~June 2014? I think it was a conference about 2 years ago or more at a College? Certainly before the NASA Ames conference which was post-EM Drive paper.
Who knows? Maybe it was a Mach-Lorentz device covered by NDA ? Is he referring to Boeing/Darpa/Serrano Field Effect that as described it had the problem that the thrust (unlike steady anomalous force for EM Drive) was skewed bi-directional pulses that would have to be made uni-directional and there is no straightforward way to do that?
20 N/Kw is not useful unless it is unidirectional
I don't recall Star-Drive discussing <<TRL2 to TRL 3, and the sustained 20 Newtons/kilowatt>> while he was posting at NSF EM Drive thread in late 2014, early 2015, which was after that conference presentation. TRL2 to TRL3 20 N/kW definitely does not sound like the EM Drive project results at NASA...
-
#2338 by frobnicat on 13 May, 2016 20:28
-
.../...
A copper surface has incident and reflected EM plane waves I and R and a transmitted wave T. The transmitted wave T is exactly that required to create the power loss in the copper. Conservation of energy requires power balance i.e. P(I)=P(T)+P(R). Momentum Balance requires the force on the copper to be M(I)-M(T)+M(R) (in terms of fluxes per unit time). Hence the momentum of the transmitted wave is directly relevant to the force on the copper, and its energy to the heat dissipated.
.../...
I don't get it about what you call transmitted wave and the momentum balance expression : in the end the EM momentum that crosses the outer surface of copper is either absorbed (or reflected ?) a few skin depth later... so it seems to me that looking the copper wall in its entirety there is no transmission (no EM energy is going through) and while M(I)-M(T)+M(R) can be considered valid as measured at the surface of copper, the copper wall in its entirety will absorb the "transmitted" momentum and thus for the copper wall we have (M(I)-M(T)+M(R))+M(T)=M(I)+M(R)=net_momentum. Or said otherwise, if looking to the bulk wall from the start we know that transmission is 0 and that net_momentum=M(I)+M(R) directly. This later expressions that goes for the bulk copper wall makes more sense to me because it can be related to the efficiency of a photon sail (orthogonal to plane wave) : when perfectly absorbing (black) momentum is what is Incident, M(R)=0 => net_momentum=M(I), and when perfectly reflecting momentum is double what is Incident, reflection is of same magnitude (and opposite direction) M(R)=M(I) => net_momentum=2×M(I). I'm trying to relate to known and classic situations, not trying (just can't) to comment on Abraham–Minkowski issues and applicability to EMdrive...
Or are you taking into account the thermal power that will radiate as IR (not as microwave) and can indeed be transmitted through the bulk of the copper wall, albeit much later ? I don't think a lot (any ?) EMdrive concept has ever been tested long enough to reach such stationary powered thermal equilibrium though... and especially not in vacuum (anyway, thermal equilibrium by convection pumping out the power losses implies much higher forces in magnitude, rendering moot the point of accounting for IR radiation pressure for atmospheric tests). The tests I recall were still seeing the temperature rising when the RF excitation was stopped, meaning that most of the power losses in copper where still used to heat copper, not quite yet radiated away 100%. So even in understanding "transmission" in this way it still can't be related to experiments where most of the incident power actually transformed in loss heat was still just "buffering" inside the bulk of copper and not (yet) transmitting through (because of not yet high enough temperature wrt. ambient bath given a certain power to dissipate).
-
#2339 by Gilbertdrive on 13 May, 2016 20:37
-
Lets back up here since I've not followed this too closely being in test stand redesign, setup, etc.,
Exactly what hypothesis is being presented to our readership here?
Are we stating the DC/AC/RF energy transmitted through wires are producing a kinetic momentum outside of Lorentz force and thermal expansion or contraction? Continuous or instantaneous?
If this is the case, my humble suggestion is to write up a brief that CLEARLY states that position with theory and numbers that back it up. Comments here, there and every few pages aren't going to convince anyone, especially me that this hypothesis has any merit.
Typical umbilical connections:
RF is 2.45 GHz consider power to be 750 watts
or
DC is 4 kV at about 0.3 mA pulsed at 60 hz
Pick a standard coax (similar to RG-8) or wire gauge such as 14
Tell us what kinetic force is presented outside of Lorentz or thermal buckling
In effect, I am challenging those who propose an error source to do what builders have to do...present their case. If this cannot be done, I humbly suggest we not keep re-hashing this topic. Its interesting, for sure, but somebody needs to present it clearly and concisely.
My message was answering to a particular questionTo date I don't recall seeing (I confess I read quickly) any scale estimates as to the errors introduced by using cabled power. Making an assertion that only battery driven tests are credible is, in that context, not science. It just smacks of cueing up an excuse to dismiss potentially positive results.
Please prove me wrong, and tell us what size of error might be created by importing mains power to a test rig.
R.
So, using Pr Yang peer-reviewed article I made a precise answer about the size of this error : At least 45mN/Kw of imported power.
The question was not only effects other than thermal. There was no effects excluded, so I answered to the question.
Your question is very different, and correspond to something far more accurate, that would need much reflexion and calculus. My message was about the RERT message that even dismissed thermal effect.
Now, rather than calculing all the possibilities, I think that the rotation of the frustrum is a very good thing to do. The Power wire "know" very few about the position of the frustrum. It still delivers the same power, still heats the same. As I had written, the only effect that I see possibly could be different between the 2 run would be the magnetic effect between the wire and the frustrum.
So, rather than calculing all possible Power wire effects, I suggest that we eliminate most of them by the frustrum reversal. I know, that is a lazy solution for me (and not for you, who do the work) I do not remember if you have forseed this reversal. I confess that I do not have your exact setup in mind, and I insist on the fact that I was not speaking about your particular setup, but about RERT question.
I am sorry, for the remaining effect, I can not make the calculus, for 2 reasons.
1 : I Am not an expert at electromagnetism. Even with all the parameters, I am not able of that.
2 : Even knowing the type of the Coaxial wire, I do not know how much magnetic field is escaping, and I do not know how to calculate the interaction with the frustrum. It would need at least the exact position of the wire, and of the frustrum. It would need to make a modelisation of all the setup. It seems to me Very complicated indeed, and would need much and precise data.
