Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1805277 times)

Offline Ricvil

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I think the emdrive is just a axion thruster.
The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).
The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).
The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017
The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.
Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.
The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.
To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by  integration of the full stress-energy tensor.
The frequency of the source must adjusted to match the condition of the ressonant backscattering.
The em field is enclosed by the cavity but the axion not.

Offline deuteragenie

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... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency,  TM212 is 6.5% lower and TE213 is 9.2% lower. frequency.
Using those estimates, Meep should have picked up TM114 (except I was exciting TE modes)  and maybe TE114. Probably not TM212 or TE213. I guess we'll see in the fields, if someone can get some numbers somehow....

1) For 10.2 inches you should place the antenna to excite an electric excitation, because the resonance is transverse electric mode shape TE013 at 2.45GHz with L=10.2 inches.  When you state that TM114 would be excited instead of TE013, does that mean that you placed the antenna to excite a magnetic instead of electric mode ?  :)  .


2) Some time ago you were able to calculate with Meep the net force on the EM Drive. It would be most interesting if you could calculate the net force on the EM Drive at every finite difference time step for the cases of rfmwguy being studied, so that we can plot the force vs. time, and see what its time behavior looks like.

There are indications in your plots that the force may not be a sine curve with time, and therefore that the force may sum up to a net amount over an integer number of periods, but we need numerical confirmation (or denial) of this.

When you say net force, you mean Maxwell stress tensor ?
Like in this example (which I have tested and works): http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Optical_forces ?

Offline OttO

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If I am correct and if MEEP is able to simulate Wood anomalies (plasmons), we could end with one OUTSIDE end surface of the frustum less reflective than the other to microwaves.

http://cpb.iphy.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=26571


I read some papers about plasmons created on the external side of a tapered wageguide by microwaves.
If we can control the reflectivity of one end (see paper on top) could it be an effect big enough?

One question that is nagging me is if the existence of plasmons on the surface cone is a function of E or B.
Could we have creation and destruction at very high frequency of them?
If that is so could we hope to a coupling with either microwaves ambient level or more dreamland like with gravity waves?



Online WarpTech

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I know how you feel, but I just found out that the surface resistance of copper at 2.4GHz is supposedly,

RS = 0.013 Ohms.

From this, you can get the power losses as the integral over the internal surface area,

P_loss = ∮S(RS*|H|2)*dS, Basically Ohm's law.

That's a pretty high resistance, so a 100mW source will hardly overcome the copper losses. Based on the heating reported, the losses are in the "watts" range at high Q. I'm sure you will need a stronger source.
Todd

I think he is planning on using an amplifier to up power to 8W, I believe.

I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

Offline VAXHeadroom

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If you can see/think another useful way to try to visualize these I'll see what I can do!  I don't understand really what I'm looking at, just processing the pictures :)  Are these different cross sections (I think they are)? I could build a semi-transparent 3d animated cross section (I think I can anyway!)...

They are cross-sections of a truncated cone.   

...

///////////////////

If you could construct 3D plots out of this information, that would be great.
The numerical data from which the plots were made should be available from aero, as all plots are constructed from numerical data.
[/quote]

Does/Can MEEP output the data in a 3D x/y/z/strength comma separated value file?  I would then be able to create a 3D plot of semi-transparent 'voxels' (bricks inside a volume) in a graphic ray-tracing program and then animate that output.  It would be beautiful :)  It would take me a few days to do the first one (just to do the coding in POVRay for the pictures), but the next one would take an hour.
Emory Stagmer
  Executive Producer, Public Speaker UnTied Music - www.untiedmusic.com

Offline Rodal

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...

They are cross-sections of a truncated cone.   

...

///////////////////

If you could construct 3D plots out of this information, that would be great.
The numerical data from which the plots were made should be available from aero, as all plots are constructed from numerical data.

Does/Can MEEP output the data in a 3D x/y/z/strength comma separated value file?  I would then be able to create a 3D plot of semi-transparent 'voxels' (bricks inside a volume) in a graphic ray-tracing program and then animate that output.  It would be beautiful :)  It would take me a few days to do the first one (just to do the coding in POVRay for the pictures), but the next one would take an hour.
My impression is that the people running Meep are doing their best to learn Meep, including learning how to output variables.  As to what is possible, just about everything is possible with Meep, even writing your own code subroutines, since Meep's code is open and available.  The problem is either finding already written code to output what one wants, or having to write the code to do it.
« Last Edit: 06/29/2015 01:50 PM by Rodal »

Offline Rodal

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... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency,  TM212 is 6.5% lower and TE213 is 9.2% lower. frequency.
Using those estimates, Meep should have picked up TM114 (except I was exciting TE modes)  and maybe TE114. Probably not TM212 or TE213. I guess we'll see in the fields, if someone can get some numbers somehow....

1) For 10.2 inches you should place the antenna to excite an electric excitation, because the resonance is transverse electric mode shape TE013 at 2.45GHz with L=10.2 inches.  When you state that TM114 would be excited instead of TE013, does that mean that you placed the antenna to excite a magnetic instead of electric mode ?  :)  .


2) Some time ago you were able to calculate with Meep the net force on the EM Drive. It would be most interesting if you could calculate the net force on the EM Drive at every finite difference time step for the cases of rfmwguy being studied, so that we can plot the force vs. time, and see what its time behavior looks like.

There are indications in your plots that the force may not be a sine curve with time, and therefore that the force may sum up to a net amount over an integer number of periods, but we need numerical confirmation (or denial) of this.

When you say net force, you mean Maxwell stress tensor ?
Like in this example (which I have tested and works): http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Optical_forces ?

I think that the force should be computed from surface integration of Maxwell's stress tensor .
The stress tensor components are force/area.  It is a tensor because the force has different components in different directions (basically force perpendicular to the area and force components tangential to the area, and the area has different normal vectors according to its orientation).

 My recollection is that aero referred to it as "force", as to how he computed it, only he can tell.

The link you provide shows how, through energy and photon-number conservation  (*), one can show that knowledge of the phase and the amplitude response of an optomechanically variable system, and its dependence on the mechanical coordinate of interest, is sufficient to compute the forces produced by light. This formalism offers a simple analytical alternative to the correct, but computationally intensive Maxwell stress-tensor methods.

As to whether this alternative is applicable, and how accurately, for the EM Drive (*), I have not had the time to check.  It is important that the algorithm you point to, purely to save computer time and avoid dealing with Maxwell's stress tensor, is making an assumption regarding entropy, since S is proportional to N (*).

__________

(*) The photon number and the internal energy are NOT conserved in a photon gas, instead, it increases strongly with temperature, see https://en.wikipedia.org/wiki/Photon_gas

« Last Edit: 06/29/2015 02:14 PM by Rodal »

Offline kdhilliard

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I just read Mr. Traveller claim on reddit that the vibration increase the thrust of the EmDrive. May I ask you folks if there was already a debate about it here? I would be glad to read about it bit more.

The most recent debate about it here with TheTraveller was on June 24, starting with this post and continuing sporadically through the next four pages, to about here.  I've brought up Shawyer's Measurement Paper several times before

~Kirk

Offline rfmwguy

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I think the emdrive is just a axion thruster.
The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).
The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).
The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017
The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.
Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.
The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.
To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by  integration of the full stress-energy tensor.
The frequency of the source must adjusted to match the condition of the ressonant backscattering.
The em field is enclosed by the cavity but the axion not.
Trouble with axions/dark matter, is its a non-detectable theoretical particle. Validation of thrust is what many of us are attempting now. Best we can do is eliminate other causes before theoretical particles...thus the tag line on all of my posts...

Offline DrBagelBites

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...

I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Offline deuteragenie

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... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency,  TM212 is 6.5% lower and TE213 is 9.2% lower. frequency.
Using those estimates, Meep should have picked up TM114 (except I was exciting TE modes)  and maybe TE114. Probably not TM212 or TE213. I guess we'll see in the fields, if someone can get some numbers somehow....

1) For 10.2 inches you should place the antenna to excite an electric excitation, because the resonance is transverse electric mode shape TE013 at 2.45GHz with L=10.2 inches.  When you state that TM114 would be excited instead of TE013, does that mean that you placed the antenna to excite a magnetic instead of electric mode ?  :)  .


2) Some time ago you were able to calculate with Meep the net force on the EM Drive. It would be most interesting if you could calculate the net force on the EM Drive at every finite difference time step for the cases of rfmwguy being studied, so that we can plot the force vs. time, and see what its time behavior looks like.

There are indications in your plots that the force may not be a sine curve with time, and therefore that the force may sum up to a net amount over an integer number of periods, but we need numerical confirmation (or denial) of this.

When you say net force, you mean Maxwell stress tensor ?
Like in this example (which I have tested and works): http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Optical_forces ?

I think that the force should be computed from surface integration of Maxwell's stress tensor .
The stress tensor components are force/area.  It is a tensor because the force has different components in different directions (basically force perpendicular to the area and force components tangential to the area, and the area has different normal vectors according to its orientation).

 My recollection is that aero referred to it as "force", as to how he computed it, only he can tell.

The link you provide shows how, through energy and photon-number conservation  (*), one can show that knowledge of the phase and the amplitude response of an optomechanically variable system, and its dependence on the mechanical coordinate of interest, is sufficient to compute the forces produced by light. This formalism offers a simple analytical alternative to the correct, but computationally intensive Maxwell stress-tensor methods.

As to whether this alternative is applicable, and how accurately, for the EM Drive (*), I have not had the time to check.  It is important that the algorithm you point to, purely to save computer time and avoid dealing with Maxwell's stress tensor, is making an assumption regarding entropy, since S is proportional to N (*).

__________

(*) The photon number and the internal energy are NOT conserved in a photon gas, instead, it increases strongly with temperature, see https://en.wikipedia.org/wiki/Photon_gas



Running the example referred to above without MPB produces results in less than 2 minutes on a 5 years old laptop.  Whereas the tutorial says that without MPB the accuracy may be reduced, the chart shows that in practice this is not really the case or is minimal.
So maybe it is possible to use this method to get at least a first idea ?

Offline rfmwguy

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I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Good ideas...if I am unable to secure a 100mW exciter today, its off to the magnetron store ;^)

Offline DrBagelBites

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I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Good ideas...if I am unable to secure a 100mW exciter today, its off to the magnetron store ;^)

My only reservations on getting a magnetron is the inherent danger that comes with them, especially the beryllium oxide found on it. I think if it comes to it, I'll try and get my hands on an amplifier simply because it is safer. Speaking of which, what is the recommended power to start using a Faraday cage? I guess the obvious answer would be when you have to ask. ;) But, I'm genuinely interested.

Offline Fractal

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I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Hello Everyone! Long time lurker (since the first original thread!) and first time poster now.

DrBagelBites: It appears to me that you are trying to perform the experiments in a non intuitive manner. Wouldn't it be better to first validate the effect using the given details from Shawyer/Rodal et al and then move into different power ranges, such as the 8W that is being attempted? To me it sounds like you are trying to work out the power ranges without first validating the principle of operation, even if there isn't a valid theory for its operation as of yet. I thought the whole point of replication was to replicate the exact phenomenon using the same equipment construction and measurement techniques. Just my 2 cents.

Offline DrBagelBites

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I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Hello Everyone! Long time lurker (since the first original thread!) and first time poster now.

DrBagelBites: It appears to me that you are trying to perform the experiments in a non intuitive manner. Wouldn't it be better to first validate the effect using the given details from Shawyer/Rodal et al and then move into different power ranges, such as the 8W that is being attempted? To me it sounds like you are trying to work out the power ranges without first validating the principle of operation, even if there isn't a valid theory for its operation as of yet. I thought the whole point of replication was to replicate the exact phenomenon using the same equipment construction and measurement techniques. Just my 2 cents.

Hello, and welcome to the forum! :)

The main reason I am attempting to do my experiment this way is simply because of money. Would I like to exactly replicate the measurement setup/equipment used? Definitely. But then you could also apply your argument to other builders as well using the fulcrum technique, or the Baby EmDrive. Everyone is trying things and we are figuring out what doesn't work. I don't think many of the DIYers have the available resources to perform the measurements that Shawyer has done.

So, back to the main argument, in the end I am doing this because it interests me and I am using my available resources to try and contribute. If it turns out to be a dud, so be it. It'll be an experience either way. I hope that clears things up. :)

-I

Offline Notsosureofit

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(*) The photon number and the internal energy are NOT conserved in a photon gas, instead, it increases strongly with temperature, see https://en.wikipedia.org/wiki/Photon_gas



Yes.  The entropy problem is quite a bit different for a monochromatic distribution and it looks. so far, that an open system formalism may be required rather than the closed Boltzmann solutions.

Offline rfmwguy

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I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Good ideas...if I am unable to secure a 100mW exciter today, its off to the magnetron store ;^)

My only reservations on getting a magnetron is the inherent danger that comes with them, especially the beryllium oxide found on it. I think if it comes to it, I'll try and get my hands on an amplifier simply because it is safer. Speaking of which, what is the recommended power to start using a Faraday cage? I guess the obvious answer would be when you have to ask. ;) But, I'm genuinely interested.
BeO is actually safe, I've been around it alot in my past life...its only when you convert it into particulates, such as drilling into it that can cause problems. Even knew a sales gal once that had BeO earrings that she wore to show how safe it is. She worked for a ceramics company. Just don't drill into it...lung exposure is the risk.

We put RF radiation up to our ears every day using cellphones at 2W and below. There is a lot of controversy on how much a person can tolerate. However, microwaves cook meat, that means you and me. Faraday the thing 100% of the time is my advice.

Edit stoopid typos...
« Last Edit: 06/29/2015 02:52 PM by rfmwguy »

Offline DrBagelBites

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I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.
Todd

You are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.

Good ideas...if I am unable to secure a 100mW exciter today, its off to the magnetron store ;^)

My only reservations on getting a magnetron is the inherent danger that comes with them, especially the beryllium oxide found on it. I think if it comes to it, I'll try and get my hands on an amplifier simply because it is safer. Speaking of which, what is the recommended power to start using a Faraday cage? I guess the obvious answer would be when you have to ask. ;) But, I'm genuinely interested.
BeO is actually safe, I've been around it alot in my past life...its only when you convert it into particulates, such as drilling into it that can cause problems. Even knew a sales gal once that had BeO earrings that she wore to show how safe it is. She worked for a ceramics company. Just don't drill into it...lung exposure is the risk.

We put RF radiation up to our ears every day using cellphones at 2W and below. There is a lot of controversy on how much a person can tolerate. However, microwaves cook meat, that means you and me. Faraday the thing 100% of the time is my advice.

Edit stoopid typos...

Right, I was worried about the particulates. Knowing me, I would accidentally drop the magnetron. So, I am going to keep my distance from them.

As far as the RF radiation levels, I'll cage it once I get out of the range of Wi-Fi power.

Offline Fractal

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DrBagelBites: Thanks for the quick and friendly response! I can certainly appreciate the monetary funding side of things and had not fully considered that factor. I certainly wish you the best of luck in your tests!

On a tangent here, and sincere apologies if this has already been thoroughly discussed and refuted, but has the electrostatic force been fully considered yet? There have been some noted anomalies with electromagnetic devices when it comes to electrostatic fields, notably Townsend Brown experiments. Here are some of the anomalies: http://www.space-mixing-theory.com/article2.pdf

I noticed that some of the discussions with electrostatic reference Q and I do seem to remember that a dielectric was being used initially in the thruster design. Any comments/feedback is welcomed. I am nowhere near the level of mathematical aptitude that so many of you are at, but I hope to contribute with rational thinking (might be counterproductive if the theory is counterintuitive here) and appreciate any insight.

Cheers, and happy building/testing!

Offline Rodal

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I think the emdrive is just a axion thruster.
The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).
The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).
The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017
The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.
Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.
The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.
To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by  integration of the full stress-energy tensor.
The frequency of the source must adjusted to match the condition of the ressonant backscattering.
The em field is enclosed by the cavity but the axion not.
Trouble with axions/dark matter, is its a non-detectable theoretical particle. Validation of thrust is what many of us are attempting now. Best we can do is eliminate other causes before theoretical particles...thus the tag line on all of my posts...

Ricvil, welcome to the forum.

The issue of axions was discussed in earlier threads.  We even had an Astrophysicist (TMEubanks) involved in the discussion.

Unfortunately, concerning an explanation, when we look at the numbers, things (including coupling) did not look good

There are experiments that have been conducted over the last few years with microwave cavities to try to detect axions in this range.  If the EM Drive force would be due to axions, it would mean that the physicists that have been looking for axions would need to be notified that Shawyer invented a more sensitive axion detector than the one they have been using, (Very unlikely), and the fact that if the EM Drive force is due to coupling with axions, how come axions have not been found despite using much more scientifically controlled experiments?

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