Author Topic: EM Drive Developments Thread 1  (Read 764877 times)

Offline JasonAW3

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Re: EM Drive Developments
« Reply #2420 on: 10/21/2014 08:46 PM »
We now have separate confirmation in both China and the USA that thrust force measurements are related to the TRANSVERSE ELECTRIC modes, since their mode shape result in greater thrust force/PowerInput than the TRANSVERSE MAGNETIC mode shapes.

This is a further challenge to explaining the measured thrust forces in these EM Drives as resulting from the magnetic field interacting with the Earth's magnetic field or with other magnetic fields (like the magnetic damper)


It also explains why NASA Eagleworks explored resonance for the mode TE012

It almost seems that the Magnetic field is interacting with Space itself in this case, much how gravity distorts spacethis configuration of a magnetic field appeasrs to be doing the same thing.

This is my thinking:

It is the electric field modes (not the magnetic modes) that show the greater Q and greater thrust, not the other way around.  There is no such thing as "thrust" using classical Maxwell's equations.  It is a closed system.  The magnetic field vectors from both bases point towards the center.  There is no net magnetic force on the center of mass using classical Maxwell's equations.

If on the other hand, one uses non-classical physics it doesn't follow that the force must come from the magnetic field, on the contrary, for example McCulloch's explanation of inertial changes due to Unruh radiation, it is the photons inertia that matters.

Great...  Quantum Physics again....  Time for the head on top of my shoulders to go explody!
My God!  It's full of universes!

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2421 on: 10/21/2014 08:54 PM »
To enable propulsion one must have an open system: ... an external aether ...

Can I vote for aether?
Sometimes I just flat out don't get it.

Offline aero

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Re: EM Drive Developments
« Reply #2422 on: 10/21/2014 10:01 PM »
Quote
QUESTION: Have you found any pictures? Any dimensions on the Chinese EM Drive?

No - Closest I have came is word description in the numerical calculation paper. He says that the diameter of the small end is just smaller than the wavelength of the fundamental frequency. Same thing Shawyer said in his email. Then

Quote
Fa=Fa1-Fa2-Fa3cosθ. In order to obtain the largest thrust, the design of the cavity requires Fa1/Fa2 to be the largest, Fa3/Fa1 to be the smallest, so Fa≈Fa1-Fa2.


where Fa1 = w_big, Fa2=w_small and Fa3 cos (theta) = height/length/or Prof. M's variable, s .

But that doesn't make a lot of sense to me. Of course with that geometry once you choose an optimum value of Fa2 of course thrust diminishes if you increase it? I guess.
« Last Edit: 10/21/2014 10:06 PM by aero »
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Offline Rodal

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Re: EM Drive Developments
« Reply #2423 on: 10/21/2014 10:15 PM »
Fa=Fa1-Fa2-Fa3cosθ. In order to obtain the largest thrust, the design of the cavity requires Fa1/Fa2 to be the largest, Fa3/Fa1 to be the smallest, so Fa≈Fa1-Fa2.


where Fa1 = w_big, Fa2=w_small and Fa3 cos (theta) = height/length/or Prof. M's variable, s .

But that doesn't make a lot of sense to me. Of course with that geometry once you choose an optimum value of Fa2 of course thrust diminishes if you increase it? I guess.
[/quote]

Thank you for having the great patience to read through that translation. 

Me primitivo-man-without AutoCAD not enjoy reading that translation and not much patience to read it. 
I have difficulty in continuing to read when things like the ones you point out don't make sense  (notice that the statement Fa2 increase diminishes thrust is the opposite of what the paper says in another place_
So much thankful to you for translating it to us and giving us the important points  ;)
« Last Edit: 10/21/2014 10:42 PM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2424 on: 10/21/2014 10:47 PM »
Does anyone reading this have a contact with the NASA Eagleworks people knowledgeable about the resonant cavity? Best bet to get accurate dimensions might be to just ask someone who knows.

Alternatively someone could calculate the wavelength of the fundamental frequency for all of the devices for which we have or need dimensions, then use the big/little ratio from Shawyer where we have actual big dimension to get a ratio. See how that ratio maps into our estimates for all of the devices. We do know the slope/taper accurately from the photos that we have. That should help guessing the length. By that I mean, since the taper/slope can be accurately picked off the photos, and for Shawyer at least, where the Big is known then we can use the height to calculate the small or the small to calculate the height, using the measurements least susceptible to error. We can also use this technique to confirm the accuracy of our measurements since they all must fit the equation:

Small = big - taper * height  and height = (big-small)/taper
« Last Edit: 10/21/2014 11:00 PM by aero »
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Offline zen-in

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Re: EM Drive Developments
« Reply #2425 on: 10/22/2014 12:13 AM »
We now have separate confirmation in both China and the USA that thrust force measurements are related to the TRANSVERSE ELECTRIC modes, since their mode shape result in greater thrust force/PowerInput than the TRANSVERSE MAGNETIC mode shapes.

This is a further challenge [ and a hint ] to explaining the measured thrust forces in these EM Drives as resulting from the magnetic field interacting with the Earth's magnetic field or with other magnetic fields (like the magnetic damper)


It also explains why NASA Eagleworks explored resonance for the mode TE012

EDIT:  Electric and magnetic fields are two interrelated aspects of the same electromagnetic tensor; the split of this tensor into electric and magnetic fields depends on the relative velocity of the observer and charge.  Therefore my original wording (challenge to thought process) should be changed to "challenge and hint".  It is a powerful hint to make us think as to what is going on.


The electromagnetic fields, standing wave or otherwise,  inside the cavity would not be expected to have any interaction with the geomagnetic field.   First they are AC and second there is no current flowing in the air.    So the claimed em mode is unrelated to any possible geomagnetic attraction.  There would have to be a DC current loop somewhere for the anomalous thrust to be caused by interaction with the geomagnetic field.    I also don't think the cavity's shape is the reason for the high Q and resonance at specific frequencies.   It isn't a waveguide.  It is just a shielded box.   The resonant frequency is determined by the loop dimensions at the feedpoint or by a 1/4 λ length of Cu fastened to the box at one end.   Here is a diagram of a cavity filter used in radio communication.   The length of the inner Cu rod determines the resonant frequency.   The cavity's size has little effect on the resonant frequency since changing the size only changes the parasitic capacitance by small amounts.

One of the drawings of the em-drive device shows an inner can shape at the small end.   It's possible that is what determines the resonant frequency and high Q.   It would have to be made from Cu and be electrically connected to the cavity at one end.
« Last Edit: 10/22/2014 12:18 AM by zen-in »

Offline Rodal

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Re: EM Drive Developments
« Reply #2426 on: 10/22/2014 12:37 AM »
We now have separate confirmation in both China and the USA that thrust force measurements are related to the TRANSVERSE ELECTRIC modes, since their mode shape result in greater thrust force/PowerInput than the TRANSVERSE MAGNETIC mode shapes.

This is a further challenge [ and a hint ] to explaining the measured thrust forces in these EM Drives as resulting from the magnetic field interacting with the Earth's magnetic field or with other magnetic fields (like the magnetic damper)


It also explains why NASA Eagleworks explored resonance for the mode TE012

EDIT:  Electric and magnetic fields are two interrelated aspects of the same electromagnetic tensor; the split of this tensor into electric and magnetic fields depends on the relative velocity of the observer and charge.  Therefore my original wording (challenge to thought process) should be changed to "challenge and hint".  It is a powerful hint to make us think as to what is going on.


The electromagnetic fields, standing wave or otherwise,  inside the cavity would not be expected to have any interaction with the geomagnetic field.   First they are AC and second there is no current flowing in the air.    So the claimed em mode is unrelated to any possible geomagnetic attraction.  There would have to be a DC current loop somewhere for the anomalous thrust to be caused by interaction with the geomagnetic field.    I also don't think the cavity's shape is the reason for the high Q and resonance at specific frequencies.   It isn't a waveguide.  It is just a shielded box.   The resonant frequency is determined by the loop dimensions at the feedpoint or by a 1/4 λ length of Cu fastened to the box at one end.   Here is a diagram of a cavity filter used in radio communication.   The length of the inner Cu rod determines the resonant frequency.   The cavity's size has little effect on the resonant frequency since changing the size only changes the parasitic capacitance by small amounts.

One of the drawings of the em-drive device shows an inner can shape at the small end.   It's possible that is what determines the resonant frequency and high Q.   It would have to be made from Cu and be electrically connected to the cavity at one end.

<< I also don't think the cavity's shape is the reason for the high Q and resonance at specific frequencies.>>

Thank your for the input.  The following considerations, however, point towards a resonating cavity where the shape governs the mode shapes:

1) Both NASA Eagleworks (Brady et.al ) and the Chinese University (Juan Yang et.al.) studied the electromagnetic modes of the cavity with Finite Element Analysis.  Both of them describe the resonant modes with the standard terminology used for transverse modes in resonating cavities (linearly polarized transverse to the plane of incidence): transverse magnetic (TM) and transverse (TE) modes accompanied by numbers.  For a cylindrical resonating cavity the first number in the subscript is the azimuthal mode number. The second number is the radial mode number. The radial mode number minus one is the number of nodes in the radial variation of Ez. The third number is the longitudinal mode number. For example: TE012 = azimuthal = 0 (it is an azimuthally symmetric mode), radial =1 (no variation of Ez), longitudinal =2 (longitudinal mode 2, for constant field it would be zero).  This detailed description of the mode shapes by NASA Eagleworks and by the Chinese is telling us that this is indeed a resonating cavity where the shape of the cavity governs  the mode shape.

See, for example http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html for a closed-form solution for a truncated cone with hemispherical ends, where the resonant modes are completely determined by the cavity shape, by the medium inside the cavity and by the material of the cavity.  This completely determines the TM and TE resonant modes and the Q.

2) In your explanation, you are proposing a different kind of resonant cavity than the one modeled by Finite Element Analysis by NASA Eagleworks and by the Chinese.  I don't understand why the Chinese and NASA Eagleworks would conduct a Finite Element Analysis modeling the drive as being a resonant cavity where Q and the resonant modes are completely due to the cavity shape if they would instead be using the type of resonator you are describing.

I attach NASA Eagleworks COMSOL Finite Element analysis of the resonant spectrum (amplitude vs frequency) at the top (and the S21 plot at the bottom) and the Finite Element Analysis of the electric field for the truncated cone.

Quoting the NASA report, regarding the presence of the RF antennas:

<<The RF drive antenna is the lower loop antenna seen in the wireframe representation of the assembly. An S11 (reflected power) plot prediction from COMSOL® is evaluated against the actual S11 output as measured by a vector network analyzer (VNA) connected to the lower antenna. Note that, in practice, a second (RF sense) antenna is present in the thruster in anticipation of implementing a phase lock loop (PLL) control approach to maintain resonance conditions over time. With the presence of the second RF sense antenna, COMSOL® can be used to provide an S21 (two-port delivered power) plot prediction that can also be evaluated against the actual S21 plot from a VNA connected to both the drive and sense antenna.>>
« Last Edit: 10/22/2014 02:40 AM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2427 on: 10/22/2014 03:10 AM »
You know, this whole thing doesn't make any sense.

For an ideal photon rocket F=P/c, = 3.3356E-09   Newtons per watt and for the EM thruster, it is F ~= P*Q/c. For the case, for example, of 850 watts with Q = 5900, P*Q/c = 16.7 mN, compared to the measured value of 16 mN. (They are not all that close but the range is 0.2 to 2, discounting Brady b" case with the Chinese cases approaching twice the total momentum of all the photons --- per second.

So the complete total of all the photons in the cavity are giving their momentum up, and more, to thrust every second. How can that possible make sense. And even don't look at the energy.

Unruh waves can't come close to making a big enough change in mass to cause lost mass to exceed the existing mass. (mi=m(1-L/4T)) For this to work, T would need to be equal to or less than L/4.

There is one way of course but if I say "Tachyons," I'll likely be banned.
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Offline ThinkerX

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Re: EM Drive Developments
« Reply #2428 on: 10/22/2014 05:34 AM »
Quote
So the complete total of all the photons in the cavity are giving their momentum up, and more, to thrust every second. How can that possible make sense. And even don't look at the energy.

Unruh waves can't come close to making a big enough change in mass to cause lost mass to exceed the existing mass. (mi=m(1-L/4T)) For this to work, T would need to be equal to or less than L/4.

There is one way of course but if I say "Tachyons," I'll likely be banned.

Then don't say 'Tachyons.'

I've has idle thoughts about a long shot possible resolution to this problem these past couple of days.

Muletron posted a video a couple days ago giving sort of a capsule history of research into subatomic particles.  The part that intrigued me was where the narrator put forth a chart showing a dozen plus subatomic particles discovered in the search for the Higgs boson.  His attitude - which I'd seen before in print - was one of embarrassed dismissal.  The attitude being these particles are a sort of unprofitable sideline, not worth detailed investigation.    Yet I wonder...might not one or more varieties of these particles hold part of the solution to this drive?  They are elementary 'building block' type critters - maybe certain rules don't fully apply to them?  Maybe they're attracted to photons? 

« Last Edit: 10/22/2014 06:13 AM by ThinkerX »

Offline aero

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Re: EM Drive Developments
« Reply #2429 on: 10/22/2014 07:44 AM »
You see, the problem is that there is more momentum being exchanged with something than the total momentum that exists within the cavity. Even if all of the phonon momentum of all of the resonating photons within the cavity were "transferred" to dark matter, there would not be enough momentum available to produce the measured thrust, particularly in the cases of the Chinese results and Shawyer b" and just barely enough in Shawyer a". And if all the resonating momentum of all the photons departed the cavity, what is there to keep resonating?

If the momentum is transferred to the quantum vacuum virtual plasma, well, there might be enough for Brady's tests data to be satisfied but it doesn't solve the problem of understanding the Jaun and Shawyer cases. There is just not enough momentum in existence in the cavity. Transfer it all and you've transferred only half enough.
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Offline Rodal

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Re: EM Drive Developments
« Reply #2430 on: 10/22/2014 12:53 PM »
You know, this whole thing doesn't make any sense.

For an ideal photon rocket F=P/c, = 3.3356E-09   Newtons per watt and for the EM thruster, it is F ~= P*Q/c. For the case, for example, of 850 watts with Q = 5900, P*Q/c = 16.7 mN, compared to the measured value of 16 mN. (They are not all that close but the range is 0.2 to 2, discounting Brady b" case with the Chinese cases approaching twice the total momentum of all the photons --- per second.

So the complete total of all the photons in the cavity are giving their momentum up, and more, to thrust every second. How can that possible make sense. And even don't look at the energy.

Unruh waves can't come close to making a big enough change in mass to cause lost mass to exceed the existing mass. (mi=m(1-L/4T)) For this to work, T would need to be equal to or less than L/4.

There is one way of course but if I say "Tachyons," I'll likely be banned.

Momentum change when a photon hits the wall is a factor of 2 times the magnitude of the photon's momentum (due to change in direction).

Assuming no losses at the wall due to the collision, (h is Planck's constant, c is speed of light, f is frequency of photon,  M is the effective mass of the wall):

Magnitude of photon's momentum before and after it hits the wall = h*f/c

Momentum change at the wall (due to change in direction): +h*f/c - (- h*f/c) = 2*h*f/c

The wall gains a momentum of 2*h*f/c

The wall gains a kinetic energy of ((2*h*f/c)^2)/(2M) = (2/M) * (h*f/c)^2

Did you include those factors of 2 ?

I think that Shawyer included the factor of 2 in his equation:

Force = (2 * PowerInput * Q /c ) * DesignFactor

If you don't include those factors of 2, you are essentially assuming a completely inelastic collision where all the photons get their energy totally dissipated at the wall and that there is no photon whatsoever bouncing off the wall again.

The index of refraction of copper is orders of magnitude greater than one (taking into account that the microwave wavelength is hundreds of thousands of micrometers, hence way to the right off the scale in the graph below).  Therefore the great majority of the photons (several orders of magnitude greater) are reflected off the wall, and very few photons have their energy dissipated at the wall. 

Hence it is much more valid to assume a factor of 2 (F ~= 2*P*Q/c) rather than a factor of 1 (F ~= P*Q/c).

Even for Solar Sails (not as reflective) it is usual to assume a factor of 1.8 instead of 1, which would give in this case F ~= 1.8*P*Q/c instead of P*Q/c.

« Last Edit: 10/22/2014 02:39 PM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2431 on: 10/22/2014 02:33 PM »
Quote
Transfer it all and you've transferred only half enough.

No. I did not use a factor of 2. If I double momentum then transfer it all, I've transferred just enough. But if it bounces off the wall then how does it transfer outside the cavity?
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Offline Rodal

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Re: EM Drive Developments
« Reply #2432 on: 10/22/2014 02:46 PM »
Quote
Transfer it all and you've transferred only half enough.

No. I did not use a factor of 2. If I double momentum then transfer it all, I've transferred just enough. But if it bounces off the wall then how does it transfer outside the cavity?

Concerning acceleration of the center of mass of the drive, that's the whole problem here again: it the problem is analyzed as a closed system using Classical Physics (Maxwell's equation with Abraham's symmetric stress tensor or with Minkowski's asymmetric stress tensor including hidden momentum) there is no acceleration of the center of mass whatsoever.

If one assumes McCulloch's model, the change in momentum for the given geometrical ratio of Length of Cavity to Diameter ratio is not small enough to produce the required acceleration for Unruh wave change of inertia modification. Although it is interesting that in Shawyer's superconducting design the length is now much smaller (compared to the other dimensions) and therefore this ratio is much closer to the one required.  For McCulloch's formulation one would have to perform: 1) a 3 dimensional analysis to properly take into account the contribution from the cone's revolving surface walls  and 2) the energy spectrum of the Unruh waves to settle this issue.

There are still other possible explanations to settle this problem:

1) possible amplification of response due to measurement: certainly this is the case when using inverted pendulums (used at NASA Eagleworks and China experiments).

2) the EM Drives may be producing a moment (around the center of mass) but not an acceleration of the center of mass. Hence if deployed in space they would not accelerate the EM Drive's center of mass.


I have been advocating for using a simple Cavendish style-measurement with oil damping (instead of magnetic damping) to settle this issue.  Brady's NASA report concludes with a sentence that JPL, Glenn and John Hopkins have proposed further measurements, but only John Hopkins has a Cavendish style-type of measurement while the other two (JPL and Glenn) are offering to use inverted pendulums again.  I wish we would get a Cavendish-type measurement (as performed by Brito Marini and Galian to nullify the MLT-type drive) at John Hopkins as soon as possible.

The inverse-square law of gravitation and the Casimir force measurements were performed with Cavendish-type experiments and not with inverted pendulums.

This is one thing (in addition to exercise and mixologists) where kernosabe John and I agree: the need to perform these experiments with a classical type of experiment (self-contained-battery-operated unit in a Cavendish balance) instead of inverted pendulums (NASA and China) or non-Cavendish balances (Shawyer).
« Last Edit: 10/23/2014 01:30 AM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2433 on: 10/22/2014 03:32 PM »
Yes, we need more and better data. But if we assume the current data is in error then we've wasted 163 pages of discussion. If the current data is right then there is not enough momentum in the system provide the measured external thrust.

Who knows of another mechanism to generate external force without momentum transfer or a reactive surface?

Casimir effect but that is internal, I've never heard of an external Casimir effect. Maybe the Unruh effect sets up a perfectly conducting surface just nanometers from the cavity ends. That could generate the outside pressure imbalance that we need.
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Offline Rodal

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Re: EM Drive Developments
« Reply #2434 on: 10/22/2014 03:43 PM »
Yes, we need more and better data. But if we assume the current data is in error then we've wasted 163 pages of discussion. If the current data is right then there is not enough momentum in the system provide the measured external thrust.

Who knows of another mechanism to generate external force without momentum transfer or a reactive surface?

Casimir effect but that is internal, I've never heard of an external Casimir effect. Maybe the Unruh effect sets up a perfectly conducting surface just nanometers from the cavity ends. That could generate the outside pressure imbalance that we need.
Well, concerning transferring momentum to the wall, it makes more sense to assume complete reflection rather than complete dissipation.  If you have a mass swinging from a pendulum elastically hitting a wall you transfer kinetic energy to the wall every time you hit the wall.  However if the swinging mass is made of completely inelastic play-doh, it will hit the wall once and that's it. [And yes perpetual motion people: I'm aware that we have to conserve energy and hence have some losses with every impact. Q is not infinite, it only ranges from 7000 to 50000 which is way smaller than infinite]






Offline aero

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Re: EM Drive Developments
« Reply #2435 on: 10/22/2014 04:06 PM »
Maybe "somehow there is"  a perfectly conducting surface set up just nanometers from the cavity ends. That could generate the outside pressure imbalance that we need.

Could the ionized air and electrons from the wall interacting with the RF wave electric and magnetic fields do something like that?

A mechanism like that would solve our momentum transfer problem as Casimir effect is an accepted phenomena and higher Q could conceivably force the "pseudo conductor plate of ionized something" closer to the wall. Decreasing plate separation increases Casimir force. That also fits.

Of course their could be an oxidation layer on the copper, too.
« Last Edit: 10/22/2014 04:27 PM by aero »
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Offline Rodal

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Re: EM Drive Developments
« Reply #2436 on: 10/22/2014 04:38 PM »
Maybe "somehow there is"  a perfectly conducting surface set up just nanometers from the cavity ends. That could generate the outside pressure imbalance that we need.

Could the ionized air and electrons from the wall interacting with the RF wave electric and magnetic fields do something like that?

A mechanism like that would solve our momentum transfer problem as Casimir effect is an accepted phenomena and higher Q could conceivably force the "pseudo conductor plate of ionized something" closer to the wall. Decreasing plate separation increases Casimir force. That also fits.

Of course their could be an oxidation layer on the copper, too.
No, there is no real and no virtual perfectly conducting wall a nanometer away from the cavity. No,  ionized air and electrons cannot form such a "virtual wall" for a Casimir type effect.  Not for a classic Casimir effect and much less for a dynamic Casimir effect.   Ions in air cannot form something acting as a wall for the Casimir effect purpose.

Were one to postulate ionized air discharge, a corona discharge essentially resulting in electrohydrodynamic thrust would be more likely.  An opposite force to the direction of discharge acting at the location where the corona discharge is taking place.  Perhaps at the gaps of the cupric structure: more likely at the gaps between the flat bases of the truncated cone and its round surface.

Too bad that none of these experiments seem to have been conducted in a vacuum, so that we cannot fully eliminate this.

« Last Edit: 10/22/2014 05:02 PM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2437 on: 10/22/2014 04:51 PM »
Maybe "somehow there is"  a perfectly conducting surface set up just nanometers from the cavity ends. That could generate the outside pressure imbalance that we need.

Could the ionized air and electrons from the wall interacting with the RF wave electric and magnetic fields do something like that?

A mechanism like that would solve our momentum transfer problem as Casimir effect is an accepted phenomena and higher Q could conceivably force the "pseudo conductor plate of ionized something" closer to the wall. Decreasing plate separation increases Casimir force. That also fits.

Of course their could be an oxidation layer on the copper, too.
No, there is no real and no virtual perfectly conducting wall a nanometer away from the cavity. No,  ionized air and electrons cannot form such a "virtual wall" for a Casimir type effect.  Not for a classic Casimir effect and much less for a dynamic Casimir effect.   Ions in air cannot form something acting as a wall for the Casimir effect purpose.

Were one to postulate ionized air discharge, a corona discharge essentially resulting in electrohydrodynamic thrust would be more likely.  An opposite force to the direction of discharge acting at the location where the corona discharge is taking place.

But a counter argument.

No, there cannot be an external force on the cavity without momentum exchange or another mechanism. The probability, as we understand physics, for thrust from this device equals the probability of a wall of electrons forming just outside the inner surface of the copper end surfaces setting up a Casimir effect.

Thereby solving one impossible situation by substituting another.
« Last Edit: 10/22/2014 04:52 PM by aero »
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Offline Rodal

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Re: EM Drive Developments
« Reply #2438 on: 10/22/2014 05:06 PM »
<<When a current passes between two electrodes — one thinner than the other — it creates a wind in the air between. If enough voltage is applied, the resulting wind can produce a thrust without the help of motors or fuel.
This phenomenon, called electrohydrodynamic thrust — or, more colloquially, “ionic wind” — was first identified in the early 20th century. ...Some researchers have theorized that ionic thrusters, if used as jet propulsion, would be extremely inefficient, requiring massive amounts of electricity to produce enough thrust to propel a vehicle.
Now researchers at MIT have run their own experiments and found that ionic thrusters may be a far more efficient source of propulsion than conventional jet engines. In their experiments, they found that ionic wind produces 110 newtons of thrust per kilowatt, compared with a jet engine’s 2 newtons per kilowatt. The team has published its results in the Proceedings of the Royal Society.
Steven Barrett, an assistant professor of aeronautics and astronautics at MIT, envisions that ionic wind may be used as a propulsion system for small, lightweight aircraft. In addition to their relatively high efficiency, ionic thrusters are silent, and invisible in infrared, as they give off no heat — ideal traits, he says, for a surveillance vehicle.
...
To measure an ion thruster’s efficiency, Barrett and Masuyama built a similarly simple setup, and hung the contraption under a suspended digital scale. They applied tens of thousands of volts, creating enough current draw to power an incandescent light bulb. They altered the distance between the electrodes, and recorded the thrust as the device lifted off the ground. Barrett says that the device was most efficient at producing lower thrust — a desirable, albeit counterintuitive, result.
“It’s kind of surprising, but if you have a high-velocity jet, you leave in your wake a load of wasted kinetic energy,” Barrett explains. “So you want as low-velocity a jet as you can, while still producing enough thrust.” He adds that an ionic wind is a good way to produce a low-velocity jet over a large area.
Getting to liftoff
Barrett acknowledges that there is one big obstacle to ionic wind propulsion: thrust density, or the amount of thrust produced per given area. Ionic thrusters depend on the wind produced between electrodes; the larger the space between electrodes, the stronger the thrust produced. That means lifting a small aircraft and its electrical power supply would require a very large air gap. Barrett envisions that electrodynamic thrusters for aircraft — if they worked — would encompass the entire vehicle.
Another drawback is the voltage needed to get a vehicle off the ground: Small, lightweight balsa models require several kilovolts. Barrett estimates a small craft, with onboard instrumentation and a power supply, would need hundreds or thousands of kilovolts.
“The voltages could get enormous,” Barrett says. “But I think that’s a challenge that’s probably solvable.” For example, he says power might be supplied by lightweight solar panels or fuel cells. Barrett says ionic thrusters might also prove useful in quieter cooling systems for laptops.
Ned Allen, chief scientist and senior fellow at Lockheed Martin Corp., says that while ionic thrusters face serious drawbacks — particularly for aerospace applications — the technology “offers nearly miraculous potential.”
“[Electrohydrodynamic thrust] is capable of a much higher efficiency than any combustion reaction device, such as a rocket or jet thrust-production device,” Allen says. Partly for this reason, Allen says Lockheed Martin is looking into the technology as a potential means of propulsion.
“Efficiency is probably the number one thing overall that drives aircraft design,” Barrett says. “[Ionic thrusters] are viable insofar as they are efficient. There are still unanswered questions, but because they seem so efficient, it’s definitely worth investigating further.”>>

http://lae.mit.edu/ehd/


« Last Edit: 10/22/2014 05:07 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #2439 on: 10/22/2014 05:15 PM »
MIT Aeronautics and Astronautics (Prof. Barrett and Masuyama, Proceedings of the Royal Society) Ionic wind maximum SPECIFIC FORCE= 110 N/kW

Shawyer SPECIFIC FORCE = 0.02 to 0.4 N/kW

IonicWind/ShawyerEMDrive specific force ratio = 5500 to 275 times

So there is plenty of room (orders of magnitude) for these EMDrives measured thrust to be due to small amounts of Ionic Wind escaping from the gaps between the flat bases of the truncated cone and the curved cone surface.

« Last Edit: 10/22/2014 05:24 PM by Rodal »

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