Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2169343 times)

Mulletron

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1580 on: 04/01/2015 12:03 AM »
....

So my most likely candidate for unloaded testing is 2413.5mhz. I have no clue what mode is being excited here.

....

Yes you have been given a strong clue in this thread  ( http://forum.nasaspaceflight.com/index.php?topic=36313.msg1352878#msg1352878 ) as to what mode is being excited here:

Mode        Frequency (GHz) [Exact sltn.]     Frequency (GHz) [COMSOL FEA]       Poynting Vector

Cyl. TE012     2.20244                                      2.1794                                                0
Cyl.TM311   2.45835                                      2.4068                                                 Towards Small Base
Cyl. TM212    2.49342                                      2.4575                                                 ~ 0

Clearly this frequency ( 2.4135 GHz) falls right in the range of the calculated frequency for mode Cyl. TM311, if the dimensions of your truncated cone are within 1% of the assumed dimensions (Big Diameter=11 inches, Small Diameter=6.25 inches and Axial Length=9 inches).

It is the best mode to excite (in that frequency range) with a cavity lacking a polymer dielectric, because this mode shape (TM311) has a clear Poynting vector.  The other modes have zero Poynting vectors in the longitudinal direction of the truncated cone.

As to why the measured frequency (if correct) is closer to the Finite Element Analysis (FEA) solution, here are possible reasons:

1) Internal dimensions of truncated cone may be 1% larger than the assumed internal dimensions in the exact solution analysis (Big Diameter=11 inches, Small Diameter=6.25 inches and Axial Length=9 inches).

2) Flatness of the big base and the small base.  The exact solution assumes spherical section surfaces for the bases while the Finite Element solution assumes them to be perfectly flat. This can be shown to make a small difference, and its sign (increasing or decreasing the frequency) depends on the electromagnetic mode shape.

3) Internal Damping: damping decreases the frequency of the damped solution as compared to the undamped solution.  The exact solution assumes infinite Q (undamped conditions).

I attach again the predicted heating profile (at the big base) for this mode (TM311) from the exact solution

Thanks for the support in digging up that data from the thread. Now that I've had time to look, I can see those on pages 25 & 26 of Frustum modes overview 2A.pdf graciously provided by Mr. Paul March here:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1333246#msg1333246

Also note that the Comsol plot on page 25 looks exactly like what you provided.

As to the few mhz difference in the first one, TM311(the TM212 one is very very close), as you alluded to, there are many reasons and hidden variables that go into this.

For example, when messing around with the frustum hooked up to the SNA, it was refreshing to see how I could change the resonant frequencies at will just my applying pressure to the large end (raising the resonant freq) and then it would return to steady state when the large end rebounded. I knew I could do that, but it was neat to see it in action.

The VSWR of TM212 was all around bad, around 5.3 or so. I think I can improve it by shortening the probe. It isn't on my list of things to do unless a reason comes up later for it.

The VSWR of TM311 isn't great, but it'll do. I was able to get it down to 1.4 by really torquing down on the cable but it would go back to ~2.

There's lots of quirks I've discovered, such as just the weight of the test cable applying pressure to the frustum walls slightly changes the measured results.

The data I've provided was reproduced after a tear down and build up of the setup to ensure the same results kept happening.

Another source of minor differences is this: So last night, I tried a test fit of the 6.25"x1" HDPE discs I made. They are as close to exactly 6.25" wide as my eyes can see. So the small end of this frustum is a hare less than 6.25" It is hard to tell exactly, but I think I'm narrow by about 1/32" of an inch. So they don't fit. Looking back at the zoomed in ruler shots, I think I can see it on the "width small end right side ruler" photo:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1345818#msg1345818

To correct for this, I'm going to have to mill them down by a small amount still to be determined. For now I can't mount them anyway because all the Nylon bolts I have are just not suitable for these big honkin chunks of plastic. Long bolts are on the way.

On the bright side of things, I was able to test the cables, connectors and the isolator I purchased and they all work up to specs. My old power splitter with port isolation still works. The isolator in particular has a VSWR of 1.03 which is good. The forward power loss was .3dB and the reverse loss is 20dB as advertized.

« Last Edit: 04/01/2015 12:48 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1581 on: 04/01/2015 12:59 AM »
....

For example, when messing around with the frustum hooked up to the SNA, it was refreshing to see how I could change the resonant frequencies at will just my applying pressure to the large end (raising the resonant freq) and then it would return to steady state when the large end rebounded. I knew I could do that, but it was neat to see it in action.

The VSWR of TM212 was all around bad, around 5.3 or so. I think I can improve it by shortening the probe. It isn't on my list of things to do unless a reason comes up later for it.

The VSWR of TM311 isn't great, but it'll do. I was able to get it down to 1.4 by really torquing down on the cable but it would go back to ~2.

There's lots of quirks I've discovered, such as just the weight of the test cable applying pressure to the frustum walls slightly changes the measured results.

....

@Mulletron, thanks for disclosing that information: as far as I know you are the first one reporting it, as I have not seen Shawer, Juan Yang or NASA Eagleworks disclose the above information.

Could you please provide more information on the movement of the natural frequency: when applying pressure to the large end, roughly  how much did the natural frequency change? roughly from what natural frequency (without outside pressure on the big end) to what natural frequency (by pushing the big end towards the inside)?
Did you push the big end at its center? Roughly speaking how much was the displacement? would you say that it was very small, of the order of the thickness or less than the thickness of the big base plate?

Thanks
« Last Edit: 04/01/2015 12:59 AM by Rodal »

Mulletron

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1582 on: 04/01/2015 01:09 AM »
....

For example, when messing around with the frustum hooked up to the SNA, it was refreshing to see how I could change the resonant frequencies at will just my applying pressure to the large end (raising the resonant freq) and then it would return to steady state when the large end rebounded. I knew I could do that, but it was neat to see it in action.

The VSWR of TM212 was all around bad, around 5.3 or so. I think I can improve it by shortening the probe. It isn't on my list of things to do unless a reason comes up later for it.

The VSWR of TM311 isn't great, but it'll do. I was able to get it down to 1.4 by really torquing down on the cable but it would go back to ~2.

There's lots of quirks I've discovered, such as just the weight of the test cable applying pressure to the frustum walls slightly changes the measured results.

....

@Mulletron, thanks for disclosing that information: as far as I know you are the first one reporting it, as I have not seen Shawer, Juan Yang or NASA Eagleworks disclose the above information.

Could you please provide more information on the movement of the natural frequency: when applying pressure to the large end, roughly  how much did the natural frequency change? roughly from what natural frequency (without outside pressure on the big end) to what natural frequency (by pushing the big end towards the inside)?
Did you push the big end at its center? Roughly speaking how much was the displacement? would you say that it was very small, of the order of the thickness or less than the thickness of the big base plate?

Thanks

Push on your LCD screen hard enough for the color to change, about that much pressure in the center of the large end. It takes deliberate force to do it. Like squeezing a shaken up Coke bottle. The change was very slight. From memory, it was only about a 1-2mhz. The SNA screen updates every 200ms so you can see it in real time. You can see the whole plot shift to the right slightly.

Another weird quirk I remember from the 700-2700mhz sweeps I did several days ago, is that you can see spikes at other frequencies on the spectrum analyzer (attached to sense port of frustum), which are other than the current center frequency being generated by the sweeper. You can't see/notice them happening unless the frequency is sweeping, otherwise they blend in. So I guess there is some mixing going on inside the cavity. Those harmonics weren't produced by the sweeper. I checked. Anyway, the reason I thought that was neat is because I remembered reading this * a few days ago when I posted it here:
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1348074#msg1348074
* https://www.vahala.caltech.edu/Research/Nonlinear

I very specifically remember being spanned on the spec anny from 700 to 2700, and when the sweeper would start over, at around 800mhz sweeper frequency, I'd see harmonics at the other end of the sweep being chased.
During this, you can even see a spike at the end:

I was sweeping from 800-2600, and spanned from 700-2700, and there are spikes outside my sweep that max hold picked up.

So I guess that means that there are n higher order modes inside these cavities happening too.
« Last Edit: 04/01/2015 01:39 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

RotoSequence

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1583 on: 04/01/2015 05:07 AM »
If I'm understanding all of these efforts correctly (please correct me if I don't!), in layman's terms, an EM drive is a conductive cavity in which most radio frequencies (RF) can propagate freely, and come out of the other end with a minimal loss of energy. But, at certain frequencies, the cavity will resonate, containing and amplifying the energy of the RF signal. For certain cavity geometries at specific frequencies, the shape (or energy?) of the resonating photons will be pointed in one direction. This directionality seems to be important for making an EM drive work. Conventional wisdom says that the energy should dissipate as heat, but instead, the energy seems to be taking the form of net thrust.

zen-in

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1584 on: 04/01/2015 05:34 AM »
If I'm understanding all of these efforts correctly (please correct me if I don't!), in layman's terms, an EM drive is a conductive cavity in which most radio frequencies (RF) can propagate freely, and come out of the other end with a minimal loss of energy. But, at certain frequencies, the cavity will resonate, containing and amplifying the energy of the RF signal. For certain cavity geometries at specific frequencies, the shape (or energy?) of the resonating photons will be pointed in one direction. This directionality seems to be important for making an EM drive work. Conventional wisdom says that the energy should dissipate as heat, but instead, the energy seems to be taking the form of net thrust.

If that is an accurate summary of the graphs, simulations and related discussion then I will have to disagree.   A long time ago an RF engineer friend explained to me that cavities, filters and LC circuits are never dissipative.   The power either goes through them or is reflected.   If an RF signal with 20 MHz of bandwidth at 2085 MHz is sent through a 5 pole cavity filter with 5 MHz passband a large fraction of the RF power is simply reflected back to the amplifier.   It is for this reason that isolators (circulators with a 50 Ohm load on one port) are used between the amplifier and a filter.    The green on black graphs shown above, unless I am mistaken are S12 plots.   Most of the power is transmitted through the cavity.   More power is reflected at frequencies where there are dips in the S12 plot.  This is where the reflection coefficient (SWR) is higher.   Inside the cavity the Poynting vector is directed from the input port to the output port.   Outside the cavity the Poynting vector is inside the dielectric of the coax; pointing away from the PA.    An interesting experiment would be to decrease the length of the coax from the PA to the cavity by 2-3 cm.   This will change the position of the dips in the S12 plot.  Any reflected power, or return wave as it's sometimes called, will be dissipated as heat inside the amplifier.
« Last Edit: 04/01/2015 05:47 AM by zen-in »

jmossman

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1585 on: 04/01/2015 06:02 AM »
I very specifically remember being spanned on the spec anny from 700 to 2700, and when the sweeper would start over, at around 800mhz sweeper frequency, I'd see harmonics at the other end of the sweep being chased.
During this, you can even see a spike at the end:

I was sweeping from 800-2600, and spanned from 700-2700, and there are spikes outside my sweep that max hold picked up.

So I guess that means that there are n higher order modes inside these cavities happening too.

Would anyone care to speculate as to how much effect spherical faces/endcaps for the small and large ends (instead of flat plates) would have on the these observed interactions?
(i.e.  "truncated spherical cone" versus as-tested "conical frustum")
« Last Edit: 04/01/2015 06:09 AM by jmossman »

RotoSequence

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1586 on: 04/01/2015 06:08 AM »
If I'm understanding all of these efforts correctly (please correct me if I don't!), in layman's terms, an EM drive is a conductive cavity in which most radio frequencies (RF) can propagate freely, and come out of the other end with a minimal loss of energy. But, at certain frequencies, the cavity will resonate, containing and amplifying the energy of the RF signal. For certain cavity geometries at specific frequencies, the shape (or energy?) of the resonating photons will be pointed in one direction. This directionality seems to be important for making an EM drive work. Conventional wisdom says that the energy should dissipate as heat, but instead, the energy seems to be taking the form of net thrust.

If that is an accurate summary of the graphs, simulations and related discussion then I will have to disagree.   A long time ago an RF engineer friend explained to me that cavities, filters and LC circuits are never dissipative.   The power either goes through them or is reflected.   If an RF signal with 20 MHz of bandwidth at 2085 MHz is sent through a 5 pole cavity filter with 5 MHz passband a large fraction of the RF power is simply reflected back to the amplifier.   It is for this reason that isolators (circulators with a 50 Ohm load on one port) are used between the amplifier and a filter.    The green on black graphs shown above, unless I am mistaken are S12 plots.   Most of the power is transmitted through the cavity.   More power is reflected at frequencies where there are dips in the S12 plot.  This is where the reflection coefficient (SWR) is higher.   Inside the cavity the Poynting vector is directed from the input port to the output port.   Outside the cavity the Poynting vector is inside the dielectric of the coax; pointing away from the PA.    An interesting experiment would be to decrease the length of the coax from the PA to the cavity by 2-3 cm.   This will change the position of the dips in the S12 plot.  Any reflected power, or return wave as it's sometimes called, will be dissipated as heat inside the amplifier.

I am not an RF engineer, and I must defer to the experts. I have no idea what's happening to the RF power inside of the cavity.

Notsosureofit

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1587 on: 04/01/2015 10:52 AM »
Real (as opposed to theoretical) tuned circuits always have resistive losses and some times nonlinear effects.

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1588 on: 04/01/2015 11:24 AM »
If I'm understanding all of these efforts correctly (please correct me if I don't!), in layman's terms, an EM drive is a conductive cavity in which most radio frequencies (RF) can propagate freely, and come out of the other end with a minimal loss of energy. But, at certain frequencies, the cavity will resonate, containing and amplifying the energy of the RF signal. For certain cavity geometries at specific frequencies, the shape (or energy?) of the resonating photons will be pointed in one direction. This directionality seems to be important for making an EM drive work. Conventional wisdom says that the energy should dissipate as heat, but instead, the energy seems to be taking the form of net thrust.

If that is an accurate summary of the graphs, simulations and related discussion then I will have to disagree.   A long time ago an RF engineer friend explained to me that cavities, filters and LC circuits are never dissipative.   The power either goes through them or is reflected.  ....

Real (as opposed to theoretical) tuned circuits always have resistive losses and some times nonlinear effects.

"That cavities, filters and LC circuits are never dissipative" is either an over-simplification or a reference to something else: exotic superconductivity (true only for certain materials at very low temperatures).   Even near absolute zero, a real sample of a normal conductor shows some resistance.

One thing is to state that dissipative losses are negligible in comparison to something and another one to flatly state that there is never any dissipation.

Non-negligible dissipated heat from induction of the magnetic field producing eddy currents in the metal has been documented by NASA Eagleworks using an IR thermal camera image of the exterior surface of the big base of the truncated cone, (for mode shape Cyl. TM212.  [Perhaps under a partial vacuum ? -I don't recall-] ).

Also Prof. Juan Yang's reported temperature vs. time measurements with embedded thermocouples throughout their EM Drive cavity (without a polymer dielectric insert) under atmospheric conditions, that, curiously, show the highest temperature at the center of the small base (trace #1), followed, at a significantly lower temperature by the temperature at the periphery of the big base (trace #5).

Also, tan delta out-of-phase losses in these cavities are not zero: the reported experiments show that the tan delta values of the materials used in these cavities is consistent with real materials experiencing out-of-phase dissipation (therefore one must use the complex form of the physical properties and not neglect the imaginary part if one is interested in assessing the finite value of Q, for example).

Stating that the cavity has no dissipation whatsoever is tantamount to stating that the cavity has an infinite Q, which for purposes of examining the EM Drive would lead to an oversimplification, as it would not allow to assess what is precisely going on at resonance.
« Last Edit: 04/01/2015 02:02 PM by Rodal »

zen-in

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1589 on: 04/01/2015 02:00 PM »
Real (as opposed to theoretical) tuned circuits always have resistive losses and some times nonlinear effects.

Resistive losses are very small in a high Q filter or cavity.   That is what is meant when it is said that filters, cavities, etc are not dissipative.  Power is either transmitted through a filter or is reflected.  A very small fraction is dissipated due to Ohmic losses.

Mulletron

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1590 on: 04/01/2015 09:33 PM »
Built a torsion head. Can adjust for height and twist. *Height adjustment is for safely entering and exiting the Galinstan, and for lining up the center of masses, for the Cavendish experiment.

Twist is for finding/adjusting zero at equilibrium, to zero the laser reflected on screen at theta zero.

Math and methodology for Cavendish:

Coulomb measured charge in similar way:

Starting at 32:30:

Man, this is turning out to be a very daunting undertaking indeed.

Rest:

*edit

*An improved clinch knot will be tied to a rigid body which sits in the detent, in the rigid channel I created in the top HDPE part, and will fall through the hollow body (without touching the sides) to the balance and DUT.

« Last Edit: 04/01/2015 10:35 PM by Mulletron »
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Stormbringer

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1591 on: 04/02/2015 06:03 AM »
i know this one has a big giggle factor but Dave Pares has updated his website again with more experimental results. It is a species of EM drive if real.

http://www.paresspacewarpresearch.org/Projet_Space_Warp/Experiment_5.htm

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ThinkerX

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1592 on: 04/03/2015 12:03 AM »
Quote
know this one has a big giggle factor but Dave Pares has updated his website again with more experimental results. It is a species of EM drive if real.

http://www.paresspacewarpresearch.org/Projet_Space_Warp/Experiment_5.htm

hmmm...worth including with the other experimental EM Drive projects or not?

Maybe this guys efforts warrant a brief look by Notsosureofit or Doctor Rodal?

Notsosureofit

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1593 on: 04/03/2015 12:44 AM »
Looks atmospheric so far but only time will tell ....

zen-in

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1594 on: 04/03/2015 03:59 AM »
i know this one has a big giggle factor but Dave Pares has updated his website again with more experimental results. It is a species of EM drive if real.

http://www.paresspacewarpresearch.org/Projet_Space_Warp/Experiment_5.htm

Whatever he's doing it looks original.   The PVC pipes with wires through them may be the solution.

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1595 on: 04/03/2015 05:29 PM »
BIG CORRECTION

It has bothered me that, if the Poynting vector (ExB) would be a quadratic function of the harmonic function so that it never changes sign and therefore does not change orientation with time, even for an AC field, as for example discussed in http://en.wikipedia.org/wiki/Poynting_vector#Time-averaged_Poynting_vector, then the operation of the EM Drive would not be a subject of so much controversy.

For the Poynting vector to vary like (Cos[ ω t + phaseAngle])^2 one needs that the E and B fields to be in phase with each other, as shown in the following image for example:

But then it dawned on me, that the E and B fields cannot be in-phase with each other (therefore the above image is only true for a travelling wave and it is inappropriate for an EM Drive cavity which instead has standing waves), because Maxwell's equation states that they must 90 degrees out of phase with each other:

One of Maxwell's equations (http://en.wikipedia.org/wiki/Faraday%27s_law_of_induction#Maxwell.E2.80.93Faraday_equation) states that:

Curl E = - d B / dt

so, for example if the magnetic field B varies as Cos[ ω t], then the electric field must vary as its time derivative:
- d(Cos[ ω t])/dt =  ω Sin[ ω t] , and therefore the Poynting vector ExB should vary as
Sin[ ω t] Cos[ ω t]  = Sin[ 2 ω t] /2, which oscillates at twice the frequency of the electromagnetic fields and has a time average value of zero.

Since the Poynting vector has a time average of zero, there cannot be any net energy flow out of the EM Drive.

This is due to the fact that the waves inside the EM Drive are standing waves.  Therefore the Poynting vector is just describing how energy is transferred between the electric and magnetic fields.

Also this means that there cannot be momentum outflow either, due to the Poynting vector, if the electromagnetic fields are harmonic functions of time.

Imagine, for discussion's sake, that it could indeed be possible that virtual electron-positron pairs would materialize out of the Quantum Vacuum, and that when such a pair materializes the Poynting vector is pointing towards the big base of the truncated cone EM Drive.  Then the electron-positron pair would be transported by the Poynting vector field towards the big base of the truncated cone, and shortly during that transport the electron-positron would cease to exist, returning back to the vacuum.  Then (as shown by Einstein himself in a though-model he proposed a long time ago concerning light particles being transported within a friction-less railroad car) the truncated cone would experience a recoil -simultaneous with the transport of the electron-positron pair-, which would result in a net force towards the small base of the truncated cone.  If the Poynting vector would always be pointing towards the big base, this would function as proposed by Dr. White.

Unfortunately, the standing waves within an EM Drive cavity are such that the E and B  fields must be 90 degrees out of phase with each other (due to Maxwell's equations), and this dictates that the Poynting vector is changing direction at a frequency twice as high as the frequency of the electromagnetic fields.  Therefore, if electron-positron pairs would materialize such as in the thought-model discussed above resulting in a recoil of the EM Drive towards the small base, it would occur just as often that electron-positron pairs would be transported in the completely opposite direction and the EM Drive would experience a force in the opposite direction.  Therefore what would be expected (out of the Quantum Vacuum model) is to have forces in the EM Drive pointing towards the small base just as often as having forces pointed in the opposite direction towards the big base, and this would result in no net transport of the EM Drive over a period of such oscillations.

I will need to correct some of my previous postings concerning the Poynting vector for the EM Drive: for a cavity like the EM Drive, the Poynting vector oscillates with time as  Sin[ 2 ω t] /2: therefore the time average of the Poynting vector must be zero.

« Last Edit: 04/05/2015 03:06 AM by Rodal »

aero

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1596 on: 04/03/2015 06:57 PM »
That's all good, (I think) but how does the big end vs. small end affect the strength of the Poynting vector  and hence magnitude of the force? Likely not at all on average? But the strength varies continuously so for small dx in positive direction it increases in strength but for same small dx in negative direction it decreases in strength. (Not sure I have the signs right.) But momentum is not the same even for the same electron/positron pair.

I am postulating that the strength of the fields in the axial direction is related to the geometry of the cavity in the axial direction. Or perhaps even the mode of the resonance. It seems unlikely that the strength is constant from one end to the other.
Retired, working interesting problems

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1597 on: 04/03/2015 07:08 PM »
That's all good, (I think) but how does the big end vs. small end affect the strength of the Poynting vector  and hence magnitude of the force? Likely not at all on average? But the strength varies continuously so for small dx in positive direction it increases in strength but for same small dx in negative direction it decreases in strength. (Not sure I have the signs right.) But momentum is not the same even for the same electron/positron pair.

I am postulating that the strength of the fields in the axial direction is related to the geometry of the cavity in the axial direction. Or perhaps even the mode of the resonance. It seems unlikely that the strength is constant from one end to the other.
If there are classical harmonic standing waves (resulting in classical resonance due to Maxwell's equations leading to a high Q) then the Poynting vector varies like Sin[ 2 ω t] /2 at twice the frequency ω of the electromagnetic fields and will average zero over a complete period of time (or multiple periods of time).

If you are postulating non-harmonic non-standing waves, we need you to  formally state and post your non-classical equations, to be able to discuss them.
« Last Edit: 04/03/2015 07:14 PM by Rodal »

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1598 on: 04/03/2015 08:04 PM »
That the electric and magnetic fields must be out of phase by 90 degrees, and therefore the Poynting vector oscillates at twice their frequency and averages zero over a period, really follows from Maxwell-Faraday's law.

" Although Faraday's law does not apply to all situations, the Maxwell–Faraday equation and Lorentz force law are always correct and can always be used directly"  (Richard Phillips Feynman, Leighton R B & Sands M L (2006). The Feynman Lectures on Physics. San Francisco: Pearson/Addison-Wesley. Vol. II, pp. 17-2. ISBN 0-8053-9049-9.)
« Last Edit: 04/03/2015 08:21 PM by Rodal »

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1599 on: 04/03/2015 08:33 PM »
I found the following paper  http://www-ssc.igpp.ucla.edu/personnel/russell/papers/skip_ed/node4.html, ( http://onlinelibrary.wiley.com/doi/10.1029/98JA02101/pdf  ) for example, that confirms the simple result I discussed above, for standing waves:

Quote
First, we may obtain some information from the simultaneous Poynting vectors as shown in Figures 5 and 6. If we consider a transverse wave causing field line oscillations, the Poynting vectors behave very differently depending on whether the wave is traveling or standing. Figure 9 is a diagram of the Poynting vectors for the two different schemes. Even though the wave amplitudes for both conditions are set to be the same and the magnitude of Poynting vector oscillations is consequently the same, the traveling wave propagates energy, while the standing wave produces no net energy flux. The Poynting vectors in Figures 5 and 6 more resemble the traveling wave pattern. Thus for the Pc3-4 wave activities in our observations the traveling wave component is stronger. We may also estimate the resonant condition by examining the phase difference between dE and dB [e.g., Singer et al., 1982]. If the phase difference is 90, the wave is standing and a resonant condition is reached.

TRAVELLING WAVE                                                   STANDING WAVE (EM Drive)

Poynting Vector time average is (+1/2)                      Poynting Vector time average is zero

(Cos[ ω t])^2  =( 1+Cos[ 2 ω t]) /2                          Sin[ ω t] Cos[ ω t]  = Sin[ 2 ω t] /2

So it is as simply as this: to transfer energy or momentum from virtual particles in the Quantum Vacuum, as proposed by Dr. White, a traveling wave would be needed, but then one would have no resonance, and no Q.

If one has a cavity EM Drive then resonance can take place, and hence a high Q, but that precludes the possibility of transferring energy or momentum, according to Maxwell's equations.
« Last Edit: 04/05/2015 03:04 AM by Rodal »

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