Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2103219 times)

Offline Thutmose

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Speaking of virtual particles, have there been any attempts to quantify the radiation spewing out of the apparatus?  Something like harmonics of 0.511MeV would be a dead giveaway to solving how this thing works (though I highly doubt it is this simple)...

The problem with this method of thrust, is that at the low power of the device tested, it would only result in about 1% or so of the measured thrust.

Assuming you have a 50w power supply (P), and 1% of that energy goes into pair production Rp, then 50% of the remainder goes into accelerated the produced pairs (K), then the impulse (I) of the device over one second can be calculated as follows:
m = Rp * P / c^2
I = ( 2 * K * m + (K/c)^2 ) ^ 0.5

where c is the speed of light.

the relativistic momentum is used as the particles end up being imparted with a few MeV/c^2 of momentum each, which seems reasonable for a single step in a RF acceleration cavity.

which results in 4.13µNs of impulse, or over 1 second, that same value of thrust.
the thrust increases as pair production rate decreases, but not significantly once less than 1% (10% the thrust is 3.75µN).

one interesting note if pair production is the factor causing thrust, assuming the power supply mentioned here https://web.archive.org/web/20041022135357/http://www.spacetransportation.com/ast/presentations/7b_vandy.pdf is feasable, and 50MWe can be produced at 1kW/kg, then such a device would accelerate at 8g

If something is horribly wrong with my maths, please correct me.

Offline Faustus

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Hooray for EM Drives!!!  We are finally catching up to the U.S.S. Enterprise!!!

Offline DoeJoe

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Let us not forget:

Kepler’s laws gave us a beautiful and powerfully predictive description of the Solar System: planets orbiting in ellipses with the Sun at its center. Newton’s Universal Theory of Gravity gave us the physics that explained Kepler’s laws but also showed that they weren’t perfect. Centuries later, Einstein’s General Relativity gave us our modern picture of gravity, showing that Newton’s gravity isn’t quite right. Science progresses by overthrowing old theories and showing that they are wrong… only, very often, the term “wrong” is over-simplistic, hiding subtleties in how science really progresses.

First presented in Second Life on June 6, 2008.


There is infinitely more that we do not know, than we know.

DJ

Offline Robotbeat

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Also, if you use the wrong solution method or too large of a timestep (or too small, sometimes!) but the equations are right, you can easily have a simulation which does not conserve energy.

Heck, if you've ever written an orbital mechanics simulation using the simple Euler's method, you often end up with your planets flung out to the stars or changing in orbits unless you use a really, really small step size (but then you get into problems with rounding!).

tl;dr: Computer simulations are no way to prove this thing works. It's easy to glitch them (by accident) into screwing up the physics. And, of course, they are no better than their underlying assumptions (and often are worse...).
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline wes_wilson

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Regarding 1):
Virtual particle pairs only exist for an extremely short time and then vanish again. One question I already asked elsewhere is: If virtual particle pairs gained momentum and they afterwards 'disappeared' again, where would the momentum go?

I just answered your question in the post you replied to...let me try explaining it again...under White's theory, if a virtual particle absorbs the momentum, then it must transfer the momentum to a different particle before it disappears.  In the vacuum of empty space, that means it propagates from one virtual particle to the next creating a wave, until the wave reaches a non-virtual particle to absorb the momentum.

Or maybe they don't disappear again at all?  Hawking radiation is one known example where the addition of energy to a virtual particle pair can promote them into real particles; and that concept's been pretty rigorously analyzed.  Maybe that's what's happening here: the energy is promoting virtual particles into real particles and the drive is exchanging momentum between the spacecraft and real particle pairs.

@SpaceX "When can I buy my ticket to Mars?"

Offline cfs

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Also, if you use the wrong solution method or too large of a timestep (or too small, sometimes!) but the equations are right, you can easily have a simulation which does not conserve energy.

Heck, if you've ever written an orbital mechanics simulation using the simple Euler's method, you often end up with your planets flung out to the stars or changing in orbits unless you use a really, really small step size (but then you get into problems with rounding!).

tl;dr: Computer simulations are no way to prove this thing works. It's easy to glitch them (by accident) into screwing up the physics. And, of course, they are no better than their underlying assumptions (and often are worse...).

Which is exactly why one needs to use mature simulation packages which have hammered out most of the important physics and weeded out most of the bugs.   ;D

When I first started writing simulations as an undergrad I remember myself thinking how much easier and quicker it would be to write simulations for detectors on my own rather than learning something as monstrously large as Geant4.  But then after taking a computational physics class where we actually got to design these basic simulations and had to worry about things such as weather or not double precision alone is enough to handle calculating derivatives in such small time steps it gave me full appreciation of how well things like Geant4 are actually able to handle the underlying physics. 

Provided one uses a more sophisticated algorithm or package which can handle these small time steps it provides an excellent way to simulate important physics -- especially in cases where it is impossible to solve the system analytically.
« Last Edit: 05/01/2015 05:12 PM by cfs »

Offline mlintin

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Light has momentum and therefore interacts with gravitational fields--the directional force of the gravity blueshifts the light as it travels towards the center of mass. This change in energy will result in an increase in momentum as the energy is increasing at an exponential rate to the increase in speed of light (the relationship is non-linear based on the redshifting equation).  What's being disproven here isn't the Law of Conservation of Momentum, but rather the consistent speed of light in a vacuum.  It's actually a theory of mine, so this is pretty neat news. I mean, obviously it's unlikely to be true.  But I've found more and more support for this (It also explains gravitational redshifting as well as special relativity concepts).   I wonder if they oriented the engine directly opposite to the direction of the gravitational force if the thrust would change, Or if they took the engine out into space into a place with no gravitational field to see what happens.  I'm fascinated by this, despite how unlikely it is to be true.

Offline flux_capacitor

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Regarding 1):
Virtual particle pairs only exist for an extremely short time and then vanish again. One question I already asked elsewhere is: If virtual particle pairs gained momentum and they afterwards 'disappeared' again, where would the momentum go?

I just answered your question in the post you replied to...let me try explaining it again...under White's theory, if a virtual particle absorbs the momentum, then it must transfer the momentum to a different particle before it disappears.  In the vacuum of empty space, that means it propagates from one virtual particle to the next creating a wave, until the wave reaches a non-virtual particle to absorb the momentum.

Or maybe they don't disappear again at all?  Hawking radiation is one known example where the addition of energy to a virtual particle pair can promote them into real particles; and that concept's been pretty rigorously analyzed.  Maybe that's what's happening here: the energy is promoting virtual particles into real particles and the drive is exchanging momentum between the spacecraft and real particle pairs.
That's also a problem. If virtual particles do appear, gain momentum then disappear, momentum conservation seems to be violated. If the virtual particles are promoted as real particles as you suggest and don't disappear, they gain momentum and conservation is preserved, but since they don't escape the cavity (which is hermetically closed) all the momentum sums to zero and there is no thrust, i.e. no EmDrive. [EDIT: it's even worse than that since in a pair production, one particle is an antiparticle, see SH answer just below]
« Last Edit: 05/01/2015 05:35 PM by flux_capacitor »

Offline SH

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Or maybe they don't disappear again at all?  Hawking radiation is one known example where the addition of energy to a virtual particle pair can promote them into real particles; and that concept's been pretty rigorously analyzed.  Maybe that's what's happening here: the energy is promoting virtual particles into real particles and the drive is exchanging momentum between the spacecraft and real particle pairs.

Vacuum fluctuations produce virtual particle-antiparticle pairs.  When real antimatter and matter come into contact they annihilate each other and produce gamma rays.   thus if the virtual particle pair were promoted to "real" particles then they would still annihilate each other and this would be observable as large amounts of gamma radiation.  Moreover, the presence of this gamma radiation (from nothingness) would violate conservation of energy.

Hawking radiation is only present at the event horizon of a black hole because, in order for it to occur, one of the virtual particles in the pair must be sucked into the black hole while the other managed to escape.  This essentially prevents the one that escaped from disappearing back into the vacuum, and energy is conserved because the positive energy of the escaped particle is cancelled out by the negative energy of the particle that got sucked into the black hole, which effectively reduces the black hole's externally measurable mass.


Offline Hexadecibel

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Regarding 1):
Virtual particle pairs only exist for an extremely short time and then vanish again. One question I already asked elsewhere is: If virtual particle pairs gained momentum and they afterwards 'disappeared' again, where would the momentum go?

I just answered your question in the post you replied to...let me try explaining it again...under White's theory, if a virtual particle absorbs the momentum, then it must transfer the momentum to a different particle before it disappears.  In the vacuum of empty space, that means it propagates from one virtual particle to the next creating a wave, until the wave reaches a non-virtual particle to absorb the momentum.

Or maybe they don't disappear again at all?  Hawking radiation is one known example where the addition of energy to a virtual particle pair can promote them into real particles; and that concept's been pretty rigorously analyzed.  Maybe that's what's happening here: the energy is promoting virtual particles into real particles and the drive is exchanging momentum between the spacecraft and real particle pairs.
That's also a problem. If virtual particles do appear, gain momentum then disappear, momentum conservation seems to be violated. If the virtual particles are promoted as real particles as you suggest and don't disappear, they gain momentum and conservation is preserved, but since they don't escape the cavity (which is hermetically closed) all the momentum sums to zero and there is no thrust, i.e. no EmDrive. [EDIT: it's even worse than that since in a pair production, one particle is an antiparticle, see SH answer just below]

I'm no physicist and this probably way off base and completely wrong... but could one explanation be that the device is somehow causing the virtual particles to tunnel?

Offline flux_capacitor

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Hawking radiation is only present at the event horizon of a black hole because, in order for it to occur, one of the virtual particles in the pair must be sucked into the black hole while the other managed to escape.  This essentially prevents the one that escaped from disappearing back into the vacuum, and energy is conserved because the positive energy of the escaped particle is cancelled out by the negative energy of the particle that got sucked into the black hole, which effectively reduces the black hole's externally measurable mass.

What you've just said assumes that antiparticles have a negative energy, which has not been proven, and it would rather be the opposite as the various papers and experiments on that subject seems to tell us that antimatter has a positive mass. Thus positive energy.

Antimatter (as per Dirac) is C-symmetry. But charge conjugation does not reverse energy. T-symmetry does. Feynman imagined another type of antiparticles, with PT-Symmetry. Those beasts would have a negative energy, and negative mass (if they have one). But they have never been observed.
« Last Edit: 05/01/2015 05:45 PM by flux_capacitor »

Offline squid

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Let us not forget:

Kepler’s laws gave us a beautiful and powerfully predictive description of the Solar System: planets orbiting in ellipses with the Sun at its center. Newton’s Universal Theory of Gravity gave us the physics that explained Kepler’s laws but also showed that they weren’t perfect. Centuries later, Einstein’s General Relativity gave us our modern picture of gravity, showing that Newton’s gravity isn’t quite right. Science progresses by overthrowing old theories and showing that they are wrong… only, very often, the term “wrong” is over-simplistic, hiding subtleties in how science really progresses.

First presented in Second Life on June 6, 2008.


There is infinitely more that we do not know, than we know.

DJ

Ah yes, but the issue is that General Relativity reduces to Newtonian gravity in the appropriate limit. Special relativity recovers newtonian mechanics at low speeds. Quantum mechanics recovers classical dynamics in the limit of large quantum number (*). QFT reduces to regular QM at low energies. And so on.

Here is a list of experiments which CANNOT be right, or would give different results if the EM drive really is coupling energy electromagnetically to something else. Others should feel free to add to the list...

1. The Michelson-Morely experiment would not give a null result
2. Atomic transition lines would be at the wrong frequencies
3. Superconducting qubits would show a reduced T1 time due to extra losses in superconducting cavities
4. Accelerator RF cavities would not work as designed, and the LHC would be unable to operate
5. The predicted standard model couplings for subatomic partices would be off
6. W and Z bosons would have different masses
6. Microwave electronics would work differently as the earth rotates around the sun
7. RF waveguide frequencies would not be as predicted
9. Stability of nuclear particles would be changed
10. Solar emission lines would be different

I remind people that the cavity is in some sense a red herring -- it just supports some electromagnetic field, which we must then assume acts on something else to generate a reaction force. You cannot make a theory which only applies in the case of a particular cavity geometry... if momentum is being anomalously generated by a particular configuration of electric and magnetic fields, all fields must create some momentum as Maxwell's equations are linear

(*) okay, for the experts, this is not quite right but you get the idea...
« Last Edit: 05/01/2015 05:56 PM by squid »

Offline squid

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Hawking radiation is only present at the event horizon of a black hole because, in order for it to occur, one of the virtual particles in the pair must be sucked into the black hole while the other managed to escape.  This essentially prevents the one that escaped from disappearing back into the vacuum, and energy is conserved because the positive energy of the escaped particle is cancelled out by the negative energy of the particle that got sucked into the black hole, which effectively reduces the black hole's externally measurable mass.

What you've just said assumes that antiparticles have a negative energy, which has not been proven, and it would rather be the opposite as the various papers and experiments on that subject seems to tell us that antimatter has a positive mass. Thus positive energy.

Antimatter (as per Dirac) is C-symmetry. But charge conjugation does not reverse energy. T-symmetry does. Feynman imagined another type of antiparticles, with PT-Symmetry. Those beasts would have a negative energy, and negative mass (if they have one). But they have never been observed.

This is a common misconception. The antiparticle does not have "negative energy". What is going on is simply that the gravitational binding energy of the particle is greater than its rest mass. To an outside observer this looks like negative energy, so to balance the books the other particle gains positive energy and the black hole mass is reduced. However, to an observer inside the event horizon, the antiparticle has positive energy.

See for example the comments by researchers (I am not a specialist in GR) in this article: http://arstechnica.com/science/2015/03/01/completely-implausible-a-controversial-paper-exists-but-so-do-black-holes/

And again, please remember that all discussion about virtual particles should view them first and foremost as calculation tools, not literally particles popping into and out of existence all the time. The fundamental quantity in QFT is always the field, and "virtual particles" refers to fluctuations in the expectation value of the field. To promote them to actual physical particles is to take Feynman diagrams a little too literally...

« Last Edit: 05/01/2015 05:55 PM by squid »

Offline flux_capacitor

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I admit this Hawking radiation thingy and its bald or hairy black hole evaporating, as well as generally speaking the QVF/zero-point energy stuff, is over my head. I like plain vanilla GR more (even including Mach's principle ;) ) Whatever, thanks for the link.
« Last Edit: 05/01/2015 06:03 PM by flux_capacitor »

Offline SH

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if momentum is being anomalously generated by a particular configuration of electric and magnetic fields, all fields must create some momentum as Maxwell's equations are linear[/b]

This is untrue.  EM fields could be used to produce a momentum indirectly by some other interaction that is nonlinear, non-monotonic, or non-differentiable.  For a simple counter example of your claim, consider an electric car.  A large amount of electricity on the motor causes it to spin and this is translated into linear momentum through the wheels...but if you reduce the amount of power, at some point the motor still stop rotating entirely and there will be zero force on the car.

Offline Rodal

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Hello, I have been following Dr. White's publications with interest since he revived the Alcubierre concept in 2003.  I have a few comments and questions below.

...

(3) Evidence in support of the QVP being mutable.  a) the force measurements of the EM-drive, b) the Casimir effect, c) as explained here (http://nextbigfuture.com/2015/02/more-emdrive-experiment-information.html), apparently Dr. White was able to show that the electron shell radii of all atoms up to atomic number 7 can be predicted based on the asumption that QVP is mutable.  I haven't read the details of that and would be curious to read where this is published if anyone knows.  d) A generic property of inflationary cosmology (as written about by Hawking, Alan Guth, Hartle, Turok, Pasachoff, Filippenko, Stenger, Vilenkin and others) is that the universe began from a small quantum fluctuation from the ground state, as stated by Vilenkin "small amount of energy was contained in that [initial] curvature, somewhat like the energy stored  in  a  strung  bow.   This  ostensible  violation  of  energy conservation is allowed by the Heisenberg uncertainty principle for sufficiently small time intervals.  The bubble then inflated exponentially and the universe grew by many orders of magnitude in a tiny fraction of a second".  Thus, it seems that inflationary cosmology is founded on a principle of mutable QVP as well.

...


Several of these questions can only be properly addressed by Dr. White and his colleagues since they best understand their theory. Addressing the EM Drive, concerning question 3) (posted above), the "evidence" although interesting, is not conclusive:

a) the force measurements of the EM-drive,

They are inconsistent.  For example, with the EM Drive re-oriented, rotated by 180 degrees so that it points in the opposite direction, the measurements differ significantly.  Need to have consistent measurements replicated at several labs (NASA Glenn, JPL, John Hopkins have been mentioned) for the evidence to be conclusive. Also, even if the data would be consistent, and the EM Drive can be used for space propulsion, that would not be conclusive evidence that its operation is due to a degradable and mutable quantum vacuum as there are several other explanations being explored.



b) the Casimir effect,

does not need to be explained by a degradable quantum vacuum.  The Casimir effect can alternatively be explained by van der Waal forces without any reference to the quantum vacuum, just based on the fine structure constant (see original publications by the great Nobel Prize winner Julian Schwinger and by Prof. Jaffe -MIT Physics department- for example)



c) Dr. White was able to show that the electron shell radii of all atoms up to atomic number 7 can be predicted based on the asumption that QVP is mutable.

Not conclusive evidence.  The prediction is approximate.  The famous astronomer Eddington (one of the first to successfully confirm General Relativity) believed in the significance of certain numbers having a physical significance that turned out to be unjustified.  Eddington argued that the value of the fine-structure constant α , could be obtained by pure deduction. He related α to the Eddington number, which was his estimate of the number of protons in the universe. This led him in 1929 to conjecture that α was exactly 1/137.



d) A generic property of inflationary cosmology (as written about by Hawking, Alan Guth, Hartle, Turok, Pasachoff, Filippenko, Stenger, Vilenkin and others) is that the universe began from a small quantum fluctuation from the ground state, as stated by Vilenkin "small amount of energy was contained in that [initial] curvature, somewhat like the energy stored  in  a  strung  bow.   This  ostensible  violation  of  energy conservation is allowed by the Heisenberg uncertainty principle for sufficiently small time intervals.  The bubble then inflated exponentially and the universe grew by many orders of magnitude in a tiny fraction of a second".  Thus, it seems that inflationary cosmology is founded on a principle of mutable QVP as well.

Not conclusive evidence because of its extremely low likelihood (based on quantum probability) of such an organized  (rather than random)  small quantum fluctuation from the ground state occurring.  In other words, the mutability and degradability of the quantum vacuum may be possible but extremely unlikely.




Conclusion: consistent experimental results need to be replicated at independent laboratories and a theoretical explanation needs to be embraced by the scientific community.
« Last Edit: 05/01/2015 06:35 PM by Rodal »

Offline CW

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Regarding 1):
Virtual particle pairs only exist for an extremely short time and then vanish again. One question I already asked elsewhere is: If virtual particle pairs gained momentum and they afterwards 'disappeared' again, where would the momentum go?

I just answered your question in the post you replied to...let me try explaining it again...under White's theory, if a virtual particle absorbs the momentum, then it must transfer the momentum to a different particle before it disappears.  In the vacuum of empty space, that means it propagates from one virtual particle to the next creating a wave, until the wave reaches a non-virtual particle to absorb the momentum.

Or maybe they don't disappear again at all?  Hawking radiation is one known example where the addition of energy to a virtual particle pair can promote them into real particles; and that concept's been pretty rigorously analyzed.  Maybe that's what's happening here: the energy is promoting virtual particles into real particles and the drive is exchanging momentum between the spacecraft and real particle pairs.
That's also a problem. If virtual particles do appear, gain momentum then disappear, momentum conservation seems to be violated. If the virtual particles are promoted as real particles as you suggest and don't disappear, they gain momentum and conservation is preserved, but since they don't escape the cavity (which is hermetically closed) all the momentum sums to zero and there is no thrust, i.e. no EmDrive.

I see your point. On the other hand, the crystal lattice of the metal cone is more like a sieve from the viewpoint of electrons/positrons, right?
Reality is weirder than fiction

Offline jknuble

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Hi Everyone,

I am an RF engineer in the Microwave Instrument Technology Branch at NASA Goddard Space Flight Center.  I had seen a few articles here and there about the EM drive and today it caught my eye on IO9.com.  While I have only spent the last hour or so reviewing what has been done to eliminated external factors to explain the phenomenon I would like to offer my two-cents.  If what I'm suggesting as an explanation has already been eliminated, I apologize.

Have you considered the effects of breakdown, and in particular multipaction and corona generation?  Multipaction breakdown events are known phenomenon on the RF radar and communication systems community.  Essentially, at high RF powers you see an effect similar to arcing within your components.  This arcing can occur between conductors and dielectrics or even between conductors in vacuum.  Sharp edges such as welds and fasteners - particularly in a cavity resonator such as this - can cause these events.  This result is damage to the interior conductor and particle generation (even in metal-only situations) as material is "burned."  In this case, the metal walls and / or contaminants of your cavity would serve as the propellant.  Corona / plasma can then develop from this particle release and exacerbate the situation.

Better descriptions can be found here : 

http://en.wikipedia.org/wiki/Multipactor_effect

http://www.microwaves101.com/encyclopedias/multipaction 

As a real world example, I am the lead engineer for the Radiometer Front End on the recently launched Soil Moisture Active Passive (SMAP) Mission. (http://smap.jpl.nasa.gov/)  We had a terrible problem with multipaction in our RF diplexer which was a cavity resonator - similar to your setup.  These devices are essentially three-port band-pass filters whose resonant frequencies are set by the physical dimensions of the (mostly) empty cavity.  Picture an empty aluminum box about 10'' x 5'' x 5''.  We saw damaging breakdown events beginning around 350W at 1.2GHz which is the nominal operating point of our radar.  It took several design iterations and many months to totally eliminate various sources of breakdown including sharp edges, gas trapped by resonator pucks, tuning screws, etc.   While your cavity and ours arn't exactly the same one could say the situations are quite similar.  The NASA Eagleworks system operated at 935MHz at (?)W, Roger Shawyer 2.45GHz at 850W, and Dr Yang at (?)MHz at 2.5KW (apologize if these missing values have been published, I didn't immediately see them).   

In a nutshell, at these power levels I would be surprised if your systems were not multipacting to some degree as designing a cavity that does not have breakdown at these levels takes a good deal of expertise on the nuances of the issue.  So as multipaction events are particle generators these could produce the force you are seeing.  What order of magnitude force we would see I havn't the foggiest.  But if I were an independent reviewer of your technology I would first ask that you prove this cannot be explained by multipaction.  Or show that even if multipaction were occuring the magnitude of the forces involved cannot be explained. These events can be observed by monitoring the RF power level passing through, or in your case reflecting, from a system.  An ideal setup would be to add an RF coupler between your magnetron and the cavity and observe the return loss into the system as power is slowly ramped up.  You will see a reflected power loss as the energy is converted into the events described.  A further test would be to have your resonator opened and carefully inspected by an expert as burn marks and other evidence can be detected optically.   

Good luck, I can pass you some names off-line if that is of interest.   If you havn't already, it would be useful to consult a high-power RF engineer, not necessarily and EM physicist (sorry guys!  :) ).  As stated, I am not an expert on this phenomenon but if there are further questions I can perhaps pass them along.

-Joseph Knuble

(Also, I hope I'm wrong!)

Offline Peter Svancarek

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Is this right? This looks to me like bad science. How could thrust fall as speed increases? I also looked to "scientific" paper on emdrive page and there is stated that at about 0.7c thrust reverses?

http://emdrive.com/sciencemissions.html
 The 15 year thrust period is based on the cathode life of the magnetron. This will be the same technology as that used in space qualified TWTA’s, which are currently specified for 15 years continuous operation.

If the 700 W (dc) engine was used as primary propulsion for a 50 kg science probe, a velocity increment of 5.6 km/sec would be achieved in the first year for a thrust of 88 mN. Thereafter, due to the effects of equation 2, the thrust falls as the velocity increases, until after 15 years, the thrust would be 16 mN at a terminal velocity approaching 30 km/sec.



Offline Rodal

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Hi Everyone,

I am an RF engineer in the Microwave Instrument Technology Branch at NASA Goddard Space Flight Center.  I had seen a few articles here and there about the EM drive and today it caught my eye on IO9.com.  While I have only spent the last hour or so reviewing what has been done to eliminated external factors to explain the phenomenon I would like to offer my two-cents.  If what I'm suggesting as an explanation has already been eliminated, I apologize.

Have you considered the effects of breakdown, and in particular multipaction and corona generation?  Multipaction breakdown events are known phenomenon on the RF radar and communication systems community.  Essentially, at high RF powers you see an effect similar to arcing within your components.  This arcing can occur between conductors and dielectrics or even between conductors in vacuum.  Sharp edges such as welds and fasteners - particularly in a cavity resonator such as this - can cause these events.  This result is damage to the interior conductor and particle generation (even in metal-only situations) as material is "burned."  In this case, the metal walls and / or contaminants of your cavity would serve as the propellant.  Corona / plasma can then develop from this particle release and exacerbate the situation.

Better descriptions can be found here : 

http://en.wikipedia.org/wiki/Multipactor_effect

http://www.microwaves101.com/encyclopedias/multipaction 

As a real world example, I am the lead engineer for the Radiometer Front End on the recently launched Soil Moisture Active Passive (SMAP) Mission. (http://smap.jpl.nasa.gov/)  We had a terrible problem with multipaction in our RF diplexer which was a cavity resonator - similar to your setup.  These devices are essentially three-port band-pass filters whose resonant frequencies are set by the physical dimensions of the (mostly) empty cavity.  Picture an empty aluminum box about 10'' x 5'' x 5''.  We saw damaging breakdown events beginning around 350W at 1.2GHz which is the nominal operating point of our radar.  It took several design iterations and many months to totally eliminate various sources of breakdown including sharp edges, gas trapped by resonator pucks, tuning screws, etc.   While your cavity and ours arn't exactly the same one could say the situations are quite similar.  The NASA Eagleworks system operated at 935MHz at (?)W, Roger Shawyer 2.45GHz at 850W, and Dr Yang at (?)MHz at 2.5KW (apologize if these missing values have been published, I didn't immediately see them).   

In a nutshell, at these power levels I would be surprised if your systems were not multipacting to some degree as designing a cavity that does not have breakdown at these levels takes a good deal of expertise on the nuances of the issue.  So as multipaction events are particle generators these could produce the force you are seeing.  What order of magnitude force we would see I havn't the foggiest.  But if I were an independent reviewer of your technology I would first ask that you prove this cannot be explained by multipaction.  Or show that even if multipaction were occuring the magnitude of the forces involved cannot be explained. These events can be observed by monitoring the RF power level passing through, or in your case reflecting, from a system.  An ideal setup would be to add an RF coupler between your magnetron and the cavity and observe the return loss into the system as power is slowly ramped up.  You will see a reflected power loss as the energy is converted into the events described.  A further test would be to have your resonator opened and carefully inspected by an expert as burn marks and other evidence can be detected optically.   

Good luck, I can pass you some names off-line if that is of interest.   If you havn't already, it would be useful to consult a high-power RF engineer, not necessarily and EM physicist (sorry guys!  :) ).  As stated, I am not an expert on this phenomenon but if there are further questions I can perhaps pass them along.

-Joseph Knuble

(Also, I hope I'm wrong!)

Welcome to the thread  :)  We hope you are here to stay  ;)

Please correct me if I'm wrong, but my understanding of this effect is that the multipactor effect occurs "when electrons accelerated by radio-frequency (RF) fields are self-sustained in a vacuum (or near vacuum)"

Quote from:  http://www.microwaves101.com/encyclopedias/multipaction   
The existence of multipaction is dependent on the following four conditions being met:

The mean free path of the electrons should be (much) greater then the spacing between the opposing surfaces, which is normally only the case in good vacuum and without any further obstruction in the way (no other di-electricum).
The average number of electrons released is greater than one which is dependent on the secondary electron yield of the surface, which in turn is dependent on the field strength (RF power) between the surfaces.
The time taken by the electron to travel from the surface from which it was released to the surface it impacts with, is to be an integer multiple of one half of the RF period (resonance).
The availability of free electrons to start of the release of secondary electrons.
(In space, free electrons are released from the surfaces by high energy particles, while during on-ground testing they are provided by a radioactive source (strontium 90) or an electron gun)

The counter-argument to this is that most of the EM Drive experiments in the US, UK and China have been conducted in ambient conditions (not in a vacuum).

The only experiments being conducted in a partial vacuum have been those conducted in the US at NASA Eagleworks since the end of December 2014.
« Last Edit: 05/01/2015 06:54 PM by Rodal »

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