Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1802819 times)

Offline PaulF

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Roger also mentioned it is best to give the internal frustum surfaces a nice bright shiny polish. No need for Silver or Gold overcoats.

Hah! I wondered that same thing last week. I mentioned this here but nobody replied on it so I don't know if it was picked up.

Offline WarpTech

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...Would TE011 actually work? 2.37GHz is below the TE01 cutoff frequency of 2.9GHz for a cylindrical waveguide of the small end (125cm).   
TE011 is actually not cut-off according to the exact solution with spherical ends for those dimensions listed above (125.7mm).   It looks good and strong, very clear signal in the exact solution.

It would have higher attenuation at the small end, which according to Todd's theory -which has my seal of approval  :) - is a plus.

I suppose that those that think that attenuation is bad may opt against, but it would be nice to test.

The only advantage I see with TE013 is that it has the Poynting vector concentrated at the small end, and a local high amplitude at the small end.

Hey Todd (WarpTech), we need to get your theory written up and in the Wiki http://emdrive.echothis.com/Theory

I hear you! Not enough hours in the day, I'm afraid.

Offline rfmwguy

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I've read engineering management papers about multi-national, multi-disciplined collaborative engineering efforts via the internet, but have never seen them in practice like this until I started reading NSF EM thread #1. I'll join others and give kudos to all and special thanks to Doc Rodal and Chris Bergan for managing/making the threads available. Keep in mind EMDrive is not a classic nuts & bolts engineering issue, but a leading-edge  project...the "effect" is there and while it might be explained or disproven someday, people here can rest assured their serious efforts will not go unnoticed.

Just a little pick-me-up for those whose brains have been pushed to the "outer limits".  :o

Offline TheTraveller

Quote
EDIT: Oh, by the way, the Poynting vector frequency is always twice the frequency of the electromagnetic field, its period is 1/2  the period of the electromagnetic field. It reverses direction twice as often as the electromagnetic fields.
So the Poynting vector is an even number of cycles no matter the number of half-cycles of the drive frequency. Well, next we ask, is the drive frequency (period, wavelength) always an interger number of half-cycles?

Seems it must be in order to resonate but the shape of the cavity and the existance of the dielectric makes one wonder, what is the effective drive frequency as far as the Poynting vector is concerned and does it remain always an even number of cycles everywhere within the cavity?

Perhaps a more salient question would be, what is the strength of the Poynting vector force over one-half cycle as that should be the maximum Poynting force attainable, and how does it compare to F = 2PQ/c?

Only the Experimental EM Drive used an internal small end dielectric. As a result, it had low Q and low thrust.

The Demonstrator and Flight Thruster EM Drives are high Q and high thrust devices which did not use a dielectric.

Shawyer says using a dielecrtic:

1) increases loss,

2) reduces Q,

3) reduces thrust.

His reported results back up that claim

So why the interest in dielectrics?

Why not? Would you be satisfies if I wrote, "and the existance or not of the dielectric"?

My 1st phase is replication, not experimentation.

Have no interest in building anything other than a Flight Thruster that is as close to the unit SPR built as possible. Too many unknowns to start changing things before I have a solid data base to go forward from.

There was no dielectric in either the Demonstrator or Flight Thruster, so there will be no dielectric in my 1st build.

As my design allows for end plate changes, I may experiment with dielectrics once I have established a soild operational unit.

Would not modify the 1st unit as it will become my control or standard unit. Would built another unit for experimentation.

1st phase Replication,
2nd phase Experimentation.

A 100W 3.85GHz Rf amp will dent the budget by $4,000 if I go with MiniCircuit unit. Have started searching ham resources for a lower cost unit.

Suggestions on other 100W 3.5-4.0GHz amps most welcome.
« Last Edit: 05/29/2015 12:18 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline WarpTech

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This was a thought occurring me a moment ago. I have just shown that inside these cavities there is a tiny gravitational effect. Per se this effect is too small account for the observed thrust, if confirmed. But, is there any change in the light propagation inside such cavities causing an asymmetry due to these small gravitational effects?
Yes.
Change gravity-> change a fundamental of space-> change time.

Personally Im still stuck in the "energy density" conundrum. If we think of space as a support mechanism acting in such a manner as to be a "carrier" of energy, and we alter an aspect of space then the energy being carried must also be impacted in some form. In stronger gravity fields spectral lines change as atoms are more compressed and molecules move more rapidly, Refraction would change. Extreme examples would be black holes.

QUESTION: What would you expect to happen to a light beam originating in normal space (the lab) traversing through a modified area of space (inside the cavity) and exiting the modified area back into normal space. Freuency shift? polarization shift?... or nothing because its back in normal space and we cant measure/detect a change

Shining a laser through a small hole in the base and top of a cavity "might" display transverse spectral changes?.  Or have 2 holes in the base and a small internal mirror attached to the cavity top...

It "might" be interesting to have a straight line of small holes directly down each side of a cavity allowing a laser to traverse directly through the cavity. Shifting the laser sequentially from bottom to top may reveal a difference in cavity internal events (or not)?.

EM waves propagating through free space reach a waveguide, what comes out the other side will depend on the dimensions and orientation of the waveguide, its conductivity, length, etc... If the dimensions of the waveguide are much smaller than the wavelength of the wave in free space, it won't pass through it. If it does pass through it, its speed will vary depending on wavelength, and the wave's phase and polarization can be altered by passing through the waveguide as well. There are twisted waveguides for just this purpose.

In GR, the stress energy tensor is what yields gravity. In EM, that tensor represents energy/momentum stored or energy/momentum flowing. The refractive index of the vacuum is also a representation of how much energy "can" be stored. Inductance & Capacitance represent those variables, they store EM energy, and in free space are represented by mu0 and eps0;

c = 1/sqrt(mu0*eps0)

The refractive index in a gravitational field, K depends on the relative values of mu and eps,

c/K = 1/sqrt(mu_rel*eps_rel)

Illustrating that the speed depends on the inductive and capacitive properties of the vacuum, that give it the ability to store the EM wave's energy. In the frustum cavity, as in a waveguide, more energy can be stored than in free space, so the velocity is slower. However, the effect is wavelength dependent, where gravity is not.

As I've said, the frustum mimics gravity over a narrow bandwidth, very well. This effect is many orders of magnitude larger than the effect predicted in Marco's paper. I think it will overwhelm any experimental evidence of the latter.

Todd



Offline TheTraveller

...A 100W 3.85GHz Rf amp will dent the budget by $4,000 if I go with MiniCircuit unit. Have started searching ham resources for a lower cost unit.

Suggestions on other 100W 3.5-4.0GHz amps most welcome.
Suggestion: start by exciting TE011 at 2.4 GHz which should be cheaper and more effective than TE013.  Look at @Notsosureofit's equation http://emdrive.echothis.com/@notsosureofit_Hypothesis (more sophisticated approach than Shawyer's)

Mode:   TE011
Frequency:   2.37833 GHz

Replicate 1st
Experiment 2nd.

Yea I know dull and boring but in my experience, when doing something very new and new to me, replication wins out at the end of the day.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

Flight Thruster build update:

From the best photo of the Flight Thruster I could find and allowing for 2mm thick walls, to add thermal mass and reduce the rate of thermal expansion, the following internal Flight Thruster dimensions were obtained:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

Applying those to my spreadsheet generated:

Df:   0.638
Frequency:   3.85GHz
Mode:   TE013

I then asked Roger Shawyer did I get close? His reply:

Df:  0.635
Frequency:   3.9003GHz
Mode:   TE013

I'm VERY happy with that as my Rf gen can easily go to that frequency. Time now to finalise drawings and get some copper sheet laser cut.

Roger also mentioned it is best to give the internal frustum surfaces a nice bright shinny polish. No need for Silver or Gold overcoats.

Will the end-plates be removable in your design? Can you do an experiment, attaching some Ferrite blocks or Metglass to the inside surface of the "big" end?

Yes both end plates are removable. Will however not modify the 1st test unit (after it is operational) as that will become my control or standard baseline unit.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

...A 100W 3.85GHz Rf amp will dent the budget by $4,000 if I go with MiniCircuit unit. Have started searching ham resources for a lower cost unit.

Suggestions on other 100W 3.5-4.0GHz amps most welcome.
Suggestion: start by exciting TE011 at 2.4 GHz which should be cheaper and more effective than TE013.  Look at @Notsosureofit's equation http://emdrive.echothis.com/@notsosureofit_Hypothesis (more sophisticated approach than Shawyer's)

Mode:   TE011
Frequency:   2.37833 GHz

Replicate 1st
Experiment 2nd.

Yea I know dull and boring but in my experience, when doing something very new and new to me, replication wins out at the end of the day.
It is your $4,000 U$D.  I hope you get all the data necessary to attain a replication (Is it possible to replicate?.  Wasn't the Flight Thruster a device made in collaboration with Boeing ? )

As I understand the story, Boeing contracted, in some form, SPR to design the Flight Thruster. I assume the 3.85GHz was chosen so as to be driven from a dual redundant Rf system Boeign had available.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

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Maybe you can borrow it :)

Online Rodal

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...

As I've said, the frustum mimics gravity over a narrow bandwidth, very well. This effect is many orders of magnitude larger than the effect predicted in Marco's paper. I think it will overwhelm any experimental evidence of the latter.

Todd
If you look at the images I posted for the Poynting vector field distribution ( http://forum.nasaspaceflight.com/index.php?topic=37642.msg1381389#msg1381389 ) for the geometry of the Flight Thruster that TheTraveller is going to use (look at the Poynting component images in the LONGITUDINAL direction only), mode TE013 has more of a fine gradient than TE012, which has a finer gradient than TE011.  The higher the longitudinal quantum number "p", the finer the graduation, with the Poynting vector being weakest at the big end and strongest at the small end.

The pictures show the Poynting vector for the first half period.  It reverses direction during the second period.

Perhaps we do want to have this gradual variation in Poynting vector strength from one end to the other, and that's the advantage of TE013. Unfortunately this is not showing the attenuation, but it is interesting to see the gradient in longitudinal direction component of the Poynting vector switching direction from cell to cell...
« Last Edit: 05/29/2015 02:20 AM by Rodal »

Offline apoc2021

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Linking this here for its mention of inverse design algorithms.

http://engineering.stanford.edu/news/stanford-engineers-breakthrough-heralds-super-efficient-light-based-computers

Who knew the shape below would be so effective at splitting IR? Only an algorithm could..

Tangentially related research, but it occurs to me that of all the possible wave guide shapes, we've really only scratched the surface. Perhaps, at some point later, it will be possible to deduce an optimal design algorithmically. Perhaps the Formulize software will be useful.


Offline WarpTech

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...

As I've said, the frustum mimics gravity over a narrow bandwidth, very well. This effect is many orders of magnitude larger than the effect predicted in Marco's paper. I think it will overwhelm any experimental evidence of the latter.

Todd
If you look at the images I posted for the Poynting vector field distribution ( http://forum.nasaspaceflight.com/index.php?topic=37642.msg1381389#msg1381389 ) for the geometry of the Flight Thruster that TheTraveller is going to use (look at the Poynting component images in the LONGITUDINAL direction only), mode TE013 has more of a fine gradient than TE02, which has a finer gradient than TE011.  The higher the longitudinal quantum number "p", the finer the graduation, with the Poynting vector being weakest at the big end and strongest at the small end.

The pictures show the Poynting vector for the first half period.  It reverses direction during the second period.

Perhaps we do want to have this gradual variation in Poynting vector strength from one end to the other, and that's the advantage of TE013. Unfortunately this is not showing the attenuation, but it is interesting to see the gradient in longitudinal direction component of the Poynting vector switching direction from cell to cell...

An interesting and curious point I'd like to make about the Poynting vector in a variable refractive index vacuum, i.e., gravitational field. This refers to the PV Model of gravity, not the frustum.

In PV, given a variable refractive index K, length, time, energy (U), momentum transform as follows;

dx => dx/sqrt(K)
dt => dt*sqrt(K)
U => U/sqrt(K)
p => p*sqrt(K)

This is such that; dx/dt => c/K, and U/p => c/K

In the case of the Poynting vector, S = E x H

The transformation in a variable refractive index is unity;

S => S, and is independent of K. However, the momentum per unit volume is highly dependent on K! 

S/c^2 =>  S*(K/c)^2

This is where I think De Aquino has it right. Please correct me if I'm wrong, but photons mediate the Lorentz force. It is the properties of the materials involved that make the Lorentz force many orders of magnitude stronger than a photon rocket. The materials set the refractive index.

How does this relate to gravity? In a gravitational field, K is larger as you approach the center of mass. This represents an increase in the ability to store energy, an increase in inductance/length and capacitance/length of space-time. Matter makes it easier to store energy as currents and potentials, in layman's terms.

So now, inside the frustum, toward the small end, we have an increased ability to store energy. This is represented in waveguides as a reduced wave velocity, or a higher refractive index. Therefore, the cavity acts as a momentum amplifier, regardless of its Q;

S/c^2 => S*(K/c)^2

I just re-read Greg Eagan's paper more thoroughly. He and Yang end with the same result, the integration of T*n over the surface. His "proof" is based on there being ONLY standing waves, of sin(wt) & cos(wt). He does not consider the Evanescent waves that are decaying into the confined volume of the small end, where c/K << c.

These would have exponentially decaying terms, exp[-a*t - b*x], where "a" and "b" are variables dependent on the shape of the cavity, per Zeng and Fan. The part that determines thrust, based on the shape of the cavity, was neglected by Egan and Yang in their analyses. Their resulting closed form equation is correct, the D, E and B, H fields they plug into it are not. Optimize their integral force equation for the correct representation for D, E and B, H, i.e., NOT standing waves, including non-linear materials, then design a system to meet those requirements.

At this point in time, that's my theory but I'm still learning, reading all this stuff and trying to keep up with all the new information compiling every day. I think De Aquino's idea of Metglass may be a good one, and I'm sure it could be modeled with the integral equation of Egan or Yang, as the properties on one of the surfaces. I just wish I had the software, and the time.

Todd

Offline WarpTech

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Therefore if we used a laser shining through an active cavity, could we "view" the distortion effect and hence have a visual analog gauge that tracks the fluctuating intensity of the "distortion" happening inside?...  a "warping-effect-gauge"

In the frustum? No, because the wavelength of the laser is many orders of magnitude smaller than the cut-off of the cavity. If anything, the light would be refracted by other things, like thermal movement in ionized air. If you evacuated it, the effects would be on the order of G/c^4. Not very easy to detect.

Since what is going on inside is at microwave frequencies, the best way to measure it is with antenna sensors and thermocouples. You can use a laser to detect the warpage of the copper. :)
 

Offline WarpTech

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Yes its shorter than cutoff, which is good as it wont be impacted by the microwaves themselves, but its traversing a modified G field (or at least a mimic of it).  Whats your thoughts on the possibility for interferometry to detect wavelength or temporal related changes of the laser?.

That's my point. It only mimics gravity over a limited bandwidth "near the cut-off wavelength". The laser's wavelength is many orders of magnitude smaller, so it doesn't see any G field. It just sees a microwave background. The "relative" temporal effects happen only to the frequencies of the waves near the cut-off wavelength of the cavity. The laser's frequency is unaffected by this. Interferometry is the wrong tool for this application, IMO.
« Last Edit: 05/29/2015 04:28 AM by WarpTech »

Offline WarpTech

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This image says it all. It shows;

1. The guide wavelength getting longer toward the small end. From this, the wave velocity, or a refractive index are equivalent representations.

2. The Poynting vector is strongest toward the small end, and weakest at the large end.

3. If the Tmn wavelengths at either end were to decay to a longer wavelengths and become evanescent, there will be a higher probability that these waves will be attenuated in the forward direction, toward the small end, due to the geometry.

4.  De Aquino is probably correct, in that when the Poynting vector strikes the material, the amount of momentum that is transferred will depend on the refractive index of the material.

S/c^2 => S*(K/c)^2

Therefore, it will out perform the thrust of a photon rocket, by modification of the equation;

F = P/c => P*(K/c)

Since copper has a very low K and diamagnetic permeability, and the frustum is copper on all sides, the Thrust is practically designed to be nil.  :o

The Q serves as nothing more than an amplifier. Sustaining higher thrust using a high Q, we can model it after a Ferro-resonant transformer. It uses the non-linear saturation of the magnetic core material to control the maximum energy stored, to put a CAP on Q. The load, or in our case the thrust, will drain from the available energy stored in the LC resonator. If Q is capped, the input supply will simply push the stored energy back up to the limit as load increases, until the stored energy can no longer support it. Then it is inherently current limited. I'm just saying, that there are ways to overcome the limitations by using non-linear materials inside. Just a thought...

Todd

Offline demofsky

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Since copper has a very low K and diamagnetic permeability, and the frustum is copper on all sides, the Thrust is practically designed to be nil.  :o

...

I'm just saying, that there are ways to overcome the limitations by using non-linear materials inside. Just a thought...

Todd

This excellent post also highlights what might be a critical source of experimental variation. 

I have lost count of the number of posts where people have described various coatings that were believed to be present on the interior of the fulstrum.  In the past the sense I have was that the coatings were noted more as a curiosity to be potentially revisited but not as a critical component of the experiment. (Of course I am referring to the entire surface and not the end plates which have been extensively discussed here.)

I also want to complement you on this post.  This really crystalised for me what we might be looking at. Thank you! :D
« Last Edit: 05/29/2015 06:15 AM by demofsky »

Offline dustinthewind

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Yes its shorter than cutoff, which is good as it wont be impacted by the microwaves themselves, but its traversing a modified G field (or at least a mimic of it).  Whats your thoughts on the possibility for interferometry to detect wavelength or temporal related changes of the laser?.

That's my point. It only mimics gravity over a limited bandwidth "near the cut-off wavelength". The laser's wavelength is many orders of magnitude smaller, so it doesn't see any G field. It just sees a microwave background. The "relative" temporal effects happen only to the frequencies of the waves near the cut-off wavelength of the cavity. The laser's frequency is unaffected by this. Interferometry is the wrong tool for this application, IMO.

Supposing the increased wavelength toward the narrow end can be paralleled to the slowing down of time and so increasing wavelength then a wave going into that well should come out of the well delayed in time?  I am thinking of how this might play with resonance in the cavity such that the light becomes more out of phase with each bounce from the narrow end, or am I mistaken?   

or what if the frequency to get the most force wasn't exactly at a resonant frequency but slightly off.
« Last Edit: 05/29/2015 06:18 AM by dustinthewind »

Offline dustinthewind

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I'm just gonna leave this here...

"Macroscopic and Direct Light Propulsion of Bulk Graphene Material"
http://arxiv.org/ftp/arxiv/papers/1505/1505.04254.pdf


Quote
The force generated from such a process/mechanism is much
larger than the force generated directly from the conventional light pressure, which is
much smaller than the force required to propel the samples.

Quote
The mechanism behind this novel phenomenon is believed to be an
efficient light-induced ejected electron emission process, following an Auger-like path
due to both the unique band structure of graphene and its macroscopic morphology of
this unique material.

This article is showing that for certain types of materials, light can impart more force to the material, than it would if it were simply used to as a photon rocket to push the same material. The difference is the Auger Effect, where the incoming light causes a population inversion in the material, that then causes electrons to be ejected from the material, greatly increasing the force by many orders of magnitude. Perhaps a similar effect can be obtained asymmetrically in a cavity?

Thank you for posting it!

Todd

My question here is what do the CoM (conservation of Edit:momentum) and CoE (conservation of energy) people think about this force on the graphene?  Obviously it is much larger than that of just light.  Do we still have a violation here?  What is interesting is it is being observed in matter.  Whats to stop them from using a mirror behind a ship and reflecting the laser to propel the ship?  It might not be the right thing to do but  we could even shove a graphene sponge in the narrow end of the cavity and let that magnetron go.  Well I diverge but my question is regarding the CoM and CoE argument. 
« Last Edit: 05/29/2015 05:36 PM by dustinthewind »

Offline Flyby

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With all the past talks about quantum fields and general relativity as reference frames for explaining EMdrive thrust, I've stumbled on this:

http://www.spacedaily.com/reports/How_spacetime_is_built_by_quantum_entanglement_999.html

not sure if it may bring something to the table...but it appears to be one of the first (theoretical) steps in developing a Theory of Everything.
Cant find the technical papers right away, but those might contain something useful for the theorists inhere? (It's way above my head anyway)

Offline Star One

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With all the past talks about quantum fields and general relativity as reference frames for explaining EMdrive thrust, I've stumbled on this:

http://www.spacedaily.com/reports/How_spacetime_is_built_by_quantum_entanglement_999.html

not sure if it may bring something to the table...but it appears to be one of the first (theoretical) steps in developing a Theory of Everything.
Cant find the technical papers right away, but those might contain something useful for the theorists inhere? (It's way above my head anyway)

I posted that yesterday but there was no general response so rather presumptuously I assumed it was of no significance.
« Last Edit: 05/29/2015 10:17 AM by Star One »

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