Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1804099 times)

Offline ElizabethGreene

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...
What about two cylindrical resonators that are at a set distance and close together but out of phase?  Doesn't this re-introduce the  phase shifted asymmetrical attenuation?

Wouldn't the fields you are trying to attenuate be trapped in the respective resonators?

I was considering the question this morning: "How could I generate an electrical field out of phase but of the same frequency as that within the resonator?"  What I've come up with so far, disclaiming that I am grossly uneducated in the topic, is
1. Electrically split the signal between the magnetron and the waveguide coupling probe.
or.
2. Insert a small probe, < 1/4 wave, into the resonator at some arbitrarily selected point, preferably near an antinode to gather the required charge from the resonator itself.

In the case of 2, you can control the collected power by the length of the probe. You can control how out-of phase it is by altering the length of the intervening bit of cable keeping in mind that the wavelength in copper will be longer than the wavelength in air.

My application is to insert the other end of the now oscillating-out-of-phase probe into an electrically insulated tube, and insert that perpendicular to the E field in the ... (I lack the correct term to describe this, help appreciated) E-field-is-moving in-and-out end of my shiny new non-tapered resonator to see if something interesting happens.

It is my intention to work on this Saturday*.

*One hopes that a related memorial service will not be held soon after.

Offline rfmwguy

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...
What about two cylindrical resonators that are at a set distance and close together but out of phase?  Doesn't this re-introduce the  phase shifted asymmetrical attenuation?

Wouldn't the fields you are trying to attenuate be trapped in the respective resonators?

(...)


Ergo, the ultimate attenuation one would think.

Here's why I chose not to start w/dielectrics.

1. shawyer and yang had none and claimed results.
2. It adds a layer of complexity when the effect is hard to prove all by itself.
3. Suspicious of reflow/outgassing/etc.
4. Added mass, increasing need for more sensitive weight measurement gear.
5. Q reduction
 
Only reason to use them in my experience was miniaturization for flight hardware. Not saying dielectrics will not work, but not ideal for EMDIYers imho.

« Last Edit: 06/17/2015 11:48 PM by rfmwguy »

Offline Acryte

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Please stop diverting away from my question.

What is YOUR TE013 resonance frequency for the 2 sets of dimensions I provided?

(Correct me if I'm wrong here)

TheTraveller, you're being a bit thick. He is saying that unless Shawyer has experimentally verified what mode he was in by taking measurements or making observations to PROVE that specific mode was in effect, that he is simply (and inaccurately) making a postulation as to what mode he BELIEVES that it is operating in, when in reality he does NOT know. Rodal is arguing that the wrong mode is being used to explain how it works, not that your work does not accurately approximate the resonant frequency and design factor etc of his devices... The formula you use coincides very well with Shawyer's own formula to calculate it, which is impressive, and we thank you for that... Yes, you are able to predict the appropriate resonant frequency that Shawyer also uses for his device, but it still doesn't prove his declaration of what mode it's operating in is an accurate statement. That mode is important to Shawyer because that's the one he uses to explain his data with inaccurate theory about open cylindrical waveguides and other things that fly in the face of common sense understanding and mathematical application regarding the system under experimentation.

Offline kml

I don't know what paper by Juan Yang contains this Fig 1 showing microwaves thrusting into space, and where is diagram b  which has placed on the exhaust a “matched load used to absorb the heat transferred from reflected microwaves”.   Does anybody know ?
Yes, I found the paper:
Yang, Juan; Wang, Yu-Quan; Ma, Yan-Jie; Li, Peng-Fei; Yang, Le; Wang, Yang; He, Guo-Qiang (May 2013). "Prediction and experimental measurement of the electromagnetic thrust generated by a microwave thruster system" (PDF). Chinese Physics B (IOP Publishing) 22 (5): 050301. doi:10.1088/1674-1056/22/5/050301

Figure 1 a) and b) from that paper attached below.

Since there is a circulator in there, the exhaust or dummy load radiation would be minimal in a well tuned system.

Offline WarpTech

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What about two cylindrical resonators that are at a set distance and close together but out of phase?  Doesn't this re-introduce the  phase shifted asymmetrical attenuation?

If I had software like COMSOL, I could answer that. It's not so easy to do by hand and I find that;

D x dB/dt + dD/dt x B = 0,

with every other scenario I've tried. I think the DC cone idea I posted this morning is uniquely possible due to the axial symmetry and radial asymmetry of the cone shape.
Todd

I was saying that because the evanescent waves (or the currents) in the two cavities walls being out of phase by pi/2 and 1/4 lambda apart interact.  One cavities evanescent waves appear to be working against the other so it is attenuated at one end.  The other is constructively interfering and working with its partner cavity evanescent waves (due to time retardation).  As a result energy is attenuated from one cavity and transported (tunneled) to the other creating a non-standing wave as a result.  It appears to be asymmetric attenuation in one cavity and asymmetric amplification in the other but with opposite wall orientation w.r.t. each cavity.  Hopefully I am not too far off in this but I think I am right.   

Are "both" the E and B fields phased the same, or are they 90 deg out of phase? In the near-field, they are typically 90 deg out of phase, and the 1/4 wave separation will make them 0 and 180 deg. So one force will be forward, the other will be backwards. So you need to look at both E and B, and forces for both. As I said, it's not an easy thing to solve by hand but for harmonic oscillations, they typically cancel. For evanescent waves, the result may generate thrust since the time average is not zero, so you could be right.

Offline rfmwguy

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https://www.aiaa-propulsionenergy.org

Welcome to the big leagues...the propulsion industry. Mega players and special interests. The conference where nasa emdrive was presented. Where boeing, rolls royce and GE listened carefully. Where they are openly talking about electric propulsion but not in the way you may think. Where you can search papers for "microwave".

And the 2015 conference occurs next month in florida.

A website where anyone interested in emdrive should visit and explore.

Where emdrive does not seem to be on the agenda.

Welcome to the playground where conventional technology titans might feel threatened...or not.

Offline RotoSequence

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Welcome to the playground where conventional technology titans might feel threatened...or not.

They're probably not feeling threatened. EM Drives are interesting at best, but the experimental evidence thus far isn't particularly compelling.  :-\

Offline aero

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Please stop diverting away from my question.

What is YOUR TE013 resonance frequency for the 2 sets of dimensions I provided?

(Correct me if I'm wrong here)

TheTraveller, you're being a bit thick. He is saying that unless Shawyer has experimentally verified what mode he was in by taking measurements or making observations to PROVE that specific mode was in effect, that he is simply (and inaccurately) making a postulation as to what mode he BELIEVES that it is operating in, when in reality he does NOT know. Rodal is arguing that the wrong mode is being used to explain how it works, not that your work does not accurately approximate the resonant frequency and design factor etc of his devices... The formula you use coincides very well with Shawyer's own formula to calculate it, which is impressive, and we thank you for that... Yes, you are able to predict the appropriate resonant frequency that Shawyer also uses for his device, but it still doesn't prove his declaration of what mode it's operating in is an accurate statement. That mode is important to Shawyer because that's the one he uses to explain his data with inaccurate theory about open cylindrical waveguides and other things that fly in the face of common sense understanding and mathematical application regarding the system under experimentation.

You didn't answer my question so this is only my guess of what the RF wave pattern looks like. I leave it to you to decide what mode it is.
Retired, working interesting problems

Offline rfmwguy

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Welcome to the playground where conventional technology titans might feel threatened...or not.

They're probably not feeling threatened. EM Drives are interesting at best, but the experimental evidence thus far isn't particularly compelling.  :-\

Maybe you are right...maybe you are wrong. Opinions can differ. But you have heard the term disruptive technologies...its a real thing...and a real concern in board rooms...been there.

Edit

Forgot the link https://en.m.wikipedia.org/wiki/Disruptive_innovation#Disruptive_technology

and

« Last Edit: 06/18/2015 03:46 AM by rfmwguy »

Offline WarpTech

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It would be interesting if one of the experimenters would hang a magnet in front and behind their frustum. Since the frustum is copper, there should not be any movement of the magnet unless DC magnetic fields are passing through it. It should be fairly easy to see if the magnets start swinging when the magnetron is turned ON.

Of course a Gauss meter sensitive to 2.5 GHz would be better for collecting data. A magnet will at least tell us if "something" is coupling through to the outside world.

Todd

Offline SeeShells

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It would be interesting if one of the experimenters would hang a magnet in front and behind their frustum. Since the frustum is copper, there should not be any movement of the magnet unless DC magnetic fields are passing through it. It should be fairly easy to see if the magnets start swinging when the magnetron is turned ON.

Of course a Gauss meter sensitive to 2.5 GHz would be better for collecting data. A magnet will at least tell us if "something" is coupling through to the outside world.

Todd
And I thought I was going to surprise everyone with my magnet idea. You're just too sharp! It is a great idea for a simple test isn't it?

Offline deltaMass

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An AC magnetic field at GHz with zero bias will show squat on a bar magnet.

Offline aero

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An AC magnetic field at GHz with zero bias will show squat on a bar magnet.

Yes, but as I understand the thought, there may be a DC bias. In which case it should show more than squat. How much more? That is the question.
Retired, working interesting problems

Offline WarpTech

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It would be interesting if one of the experimenters would hang a magnet in front and behind their frustum. Since the frustum is copper, there should not be any movement of the magnet unless DC magnetic fields are passing through it. It should be fairly easy to see if the magnets start swinging when the magnetron is turned ON.

Of course a Gauss meter sensitive to 2.5 GHz would be better for collecting data. A magnet will at least tell us if "something" is coupling through to the outside world.

Todd
And I thought I was going to surprise everyone with my magnet idea. You're just too sharp! It is a great idea for a simple test isn't it?

I think so. Yesterday when I offered my conjecture that the currents are DC, I hadn't realized that a microwave magnetron is said to operate on a 50% duty cycle. The easiest way to do that is a 1/2 wave rectifier. That got me thinking that maybe the waves are driven with a DC offset from the transformer, and exponentially decay right out of the magnetron.

Offline rfmwguy

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It would be interesting if one of the experimenters would hang a magnet in front and behind their frustum. Since the frustum is copper, there should not be any movement of the magnet unless DC magnetic fields are passing through it. It should be fairly easy to see if the magnets start swinging when the magnetron is turned ON.

Of course a Gauss meter sensitive to 2.5 GHz would be better for collecting data. A magnet will at least tell us if "something" is coupling through to the outside world.

Todd
And I thought I was going to surprise everyone with my magnet idea. You're just too sharp! It is a great idea for a simple test isn't it?

I think so. Yesterday when I offered my conjecture that the currents are DC, I hadn't realized that a microwave magnetron is said to operate on a 50% duty cycle. The easiest way to do that is a 1/2 wave rectifier. That got me thinking that maybe the waves are driven with a DC offset from the transformer, and exponentially decay right out of the magnetron.

Hmmm, methinks the voltage doubler cap and diode circuit generating 4kv bias from a 2kv transformer on everyday microwave power supplies does indeed cause the 50% duty cycle. Its pulsed, as in radar...rapidly expanding and collapsing fields...the buzzing noise julian commented on...tilt  :o

Offline WarpTech

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An AC magnetic field at GHz with zero bias will show squat on a bar magnet.

Correcto! But a DC magnetic field is not shielded by copper and evanescent waves do not have time averages equal to zero. Therefore, the volt-seconds product applied to the conductors by the E field is not 100% canceled on each cycle. A DC bias can (and probably does) exist, and that is what can escape outside the copper walls because the skin effect does not apply.

I'm working on the paper now to show a DC field will exert thrust on a conical section, without microwaves. As it moves forward, B-field escapes, lowering the potential energy and impedance, allowing it to draw more power from the battery. Watt goes in is Watt comes out! :) It is a near-field photon rocket that works due to inefficient coupling and leakage inductance. It may not work, but I'm going to write it up anyway.

Since gravity in the PV Model is basically a gradient in the inductance and capacitance, it is simply another expression of how it mimics gravity. It has a DC bias in one direction and this is unique to a cone!
Todd
 

Offline WarpTech

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It would be interesting if one of the experimenters would hang a magnet in front and behind their frustum. Since the frustum is copper, there should not be any movement of the magnet unless DC magnetic fields are passing through it. It should be fairly easy to see if the magnets start swinging when the magnetron is turned ON.

Of course a Gauss meter sensitive to 2.5 GHz would be better for collecting data. A magnet will at least tell us if "something" is coupling through to the outside world.

Todd
And I thought I was going to surprise everyone with my magnet idea. You're just too sharp! It is a great idea for a simple test isn't it?

I think so. Yesterday when I offered my conjecture that the currents are DC, I hadn't realized that a microwave magnetron is said to operate on a 50% duty cycle. The easiest way to do that is a 1/2 wave rectifier. That got me thinking that maybe the waves are driven with a DC offset from the transformer, and exponentially decay right out of the magnetron.

Hmmm, methinks the voltage doubler cap and diode circuit generating 4kv bias from a 2kv transformer on everyday microwave power supplies does indeed cause the 50% duty cycle. Its pulsed, as in radar...rapidly expanding and collapsing fields...the buzzing noise julian commented on...tilt  :o

I found some schematics for microwave ovens. Yup... that's exactly how it works. The magnetron sees only a 0.7V diode-drop on it's input during the positive half-cycle at 60Hz, and -4kV with an exponential decaying  voltage on the negative half-cycle, with a time constant set by the capacitor and the power consumption of the Magnetron. Such a source is probably 99.999% guaranteed to produce an accumulated DC offset in a low-impedance short-circuit such as a frustum.

Therefore, rather conclusively then, exponentially decaying evanescent waves are not only caused by the geometry, they are being input by the source!

That could be a key difference then between those who used Magnetrons, and Brady who used an RF amplifier. I recall Star Drive saying that "dithering the input" seemed to have the best results.
Todd

Offline dustinthewind

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What about two cylindrical resonators that are at a set distance and close together but out of phase?  Doesn't this re-introduce the  phase shifted asymmetrical attenuation?

If I had software like COMSOL, I could answer that. It's not so easy to do by hand and I find that;

D x dB/dt + dD/dt x B = 0,

with every other scenario I've tried. I think the DC cone idea I posted this morning is uniquely possible due to the axial symmetry and radial asymmetry of the cone shape.
Todd

I was saying that because the evanescent waves (or the currents) in the two cavities walls being out of phase by pi/2 and 1/4 lambda apart interact.  One cavities evanescent waves appear to be working against the other so it is attenuated at one end.  The other is constructively interfering and working with its partner cavity evanescent waves (due to time retardation).  As a result energy is attenuated from one cavity and transported (tunneled) to the other creating a non-standing wave as a result.  It appears to be asymmetric attenuation in one cavity and asymmetric amplification in the other but with opposite wall orientation w.r.t. each cavity.  ...

Are "both" the E and B fields phased the same, or are they 90 deg out of phase? In the near-field, they are typically 90 deg out of phase, and the 1/4 wave separation will make them 0 and 180 deg. So one force will be forward, the other will be backwards. So you need to look at both E and B, and forces for both. As I said, it's not an easy thing to solve by hand but for harmonic oscillations, they typically cancel. For evanescent waves, the result may generate thrust since the time average is not zero, so you could be right.

Initially the E and B fields (light and evanescent waves) in the cavities are in phase till you bring them close and they interfere.  I would assume the evanescent waves of cavity one interacts with the evanescent waves of cavity two which are not in phase.  This interaction then should cause the phase of the evanescent waves in the two separate cavities to drift closer together and as a result light should start to tunnel through from cavity one to two or visa versa depending on the phase relationship.  This new light introduced into the cavity by the interaction is a bit out of phase with even the bottom plate I would assume.  By manipulating the phase and amplitude of light coming into the two cavities I was thinking we could keep the evanescent waves in this phase relationship. 

Yes exactly with time delay one cavity sees 0 degrees out of phase E field evanescent wave and the other cavity sees 180 degrees out of phase evanescent wave.  The resulting interaction produces forces in the same direction and is similar to how a phase array antenna works to focus radiation with out any moving parts. 

Your right that the capacitance seems to work against the magnetic field and almost appears to be the relativistic working against the static.  I was looking at the TE01 mode for a cylindrical cavity and the E-field circles the axis and appears to be induced by the light.  In a wire I can see how by capacitance charge builds up from current flow in the wire and so we have evanescent waves shifting from magnetic to static E-field.  One issue is I am not seeing how the TE01 mode in a cylindrical cavity can build up that static E-field.  The currents are symmetric with the plate and just circle around the axis so am I wrong in thinking the evanescent waves in the TE01 mode are magnetic but seem to be lacking static charge build up? 
« Last Edit: 06/18/2015 10:32 AM by dustinthewind »

Offline TheTraveller

IXS Clark. Powered by 20 EMDrives from a stern mounted nuclear reactor. Same guy who designed the EagleWorks Warp Ship.

https://m.flickr.com/#/photos/123021064@N05/

Can see the microwave feed into the big end of the frustum and small end thrusting the ship forward.

Told me he was commissioned to do this work by same source that commissioned him to do the Warp Ship work.
« Last Edit: 06/18/2015 11:40 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 Rodal

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Please stop diverting away from my question.

What is YOUR TE013 resonance frequency for the 2 sets of dimensions I provided?

(Correct me if I'm wrong here)

TheTraveller, you're being a bit thick. He is saying that unless Shawyer has experimentally verified what mode he was in by taking measurements or making observations to PROVE that specific mode was in effect, that he is simply (and inaccurately) making a postulation as to what mode he BELIEVES that it is operating in, when in reality he does NOT know. Rodal is arguing that the wrong mode is being used to explain how it works, not that your work does not accurately approximate the resonant frequency and design factor etc of his devices... The formula you use coincides very well with Shawyer's own formula to calculate it, which is impressive, and we thank you for that... Yes, you are able to predict the appropriate resonant frequency that Shawyer also uses for his device, but it still doesn't prove his declaration of what mode it's operating in is an accurate statement. That mode is important to Shawyer because that's the one he uses to explain his data with inaccurate theory about open cylindrical waveguides and other things that fly in the face of common sense understanding and mathematical application regarding the system under experimentation.

You didn't answer my question so this is only my guess of what the RF wave pattern looks like. I leave it to you to decide what mode it is.

@aero

Is that the electromagnetic field that MEEP 3D predicts for the Flight Thruster?



The field variation in the azimuthal (circumferential) direction "m" looks definitely like having a value of m=1 instead of the value of m=0 for TE013 (m=0,n=1,p=3).

See this chart:



 It doesn't look like the mode shape TE013 that TheTraveller says that Shawyer believes the Flight Thruster should have experienced, based on Shawyer's calculations.  Unfortunately I understand that Shawyer did not perform any experimental verification of what the actual mode shape actually was, so it doesn't look like we can ever be sure what mode shape the Flight Thruster actually experienced. 

The only researcher that has experimentally verified a mode shape, to my knowledge, has been Paul March at NASA, who experimentally verified mode shape TM212 for NASA's truncated cone cavity.




@Traveler

Quote
Frustum big diameter        m   0.2314000
Frustum small diameter   m   0.1257000
Frustum centre length   m   0.1386000

and asked him for the resonate frequency. He sent me the following:

External Rf                   Hz   3,900,300,000

I would prefer not to make an assumption, so I will ask. "Are those internal dimensions?" And, "Are the end plates flat or curved?"

Regarding lack of response on dimensions for the Flight Thruster, yes these are the dimensions that I recall were given by TheTraveller at some point in time (I lost track whether these are the latest or why would they have changed):

Cavity Length (m)   big diameter (m)   small diameter (m)

0.1386                     0.2314                    0.1257

Congratulations on making such great progress with MEEP where you can now run 3D models.

Additionally, there is the issue of what the excitation RF frequency was.  In Shaywer's publications, Shawyer gives 3.85 GHz for the Flight Thruster, but in that quotation TheTraveller is saying that External Rf was instead 3.90 GHz?

What excitation frequency did you use for your MEEP 3 D analysis ? (3.85 GHz or 3.90 GHz ?)

How much computer time do these MEEP 3D runs take ?

Are you running them on the same computer that you were using to run the MEEP 2D models ?
« Last Edit: 06/18/2015 12:44 PM by Rodal »

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