EM Drive Developments - related to space flight applications - Thread 7

[madsci]

  Monomorphic,

  If I'm not mistaken you were working on an optical EmDrive:

   https://www.reddit.com/r/EmDrive/comments/3p1atx/optical_em_drive/

  What happened to that project ?

The wavelength is much smaller in the optical range and the force predicted by all EM Drive theories should be much, much smaller in the optical range with a small micro-dimensioned  EM Drive.

See:

https://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347


Conversely if instead of using an EM Drive with very small micro dimensions, the plan was to use an EM Drive with dimensions similar to the ones built up to now, the mode shape would be extremely high at optical frequencies, and such very high modes are small amplitude. A FEKO simulation would show this.

  Thanks for the answer.
  If I'm not mistaken in Shawyer's theory/formula, the thrust doesn't depend on the wavelength, but it's proportional to:
     -the input power
     -the quality factor Q
  Since the input power is around 12W and Q is in the millions (according to the posts on Reddit), the resulting thrust should be even bigger than the one expected from the 2.45 GHz emdrives.

  Am I missing something here ?

P.S.:
  This is the thread where Q is discussed:

     https://www.reddit.com/r/EmDrive/comments/42uzo7/opticallaser_emdrive_revealed/

The interesting post is this:

Monomorphic 2 points 1 month ago

I calculated this a few months back. Q would be somewhere around 9,000,000 with the aluminum mirrors. ~70,000,000 with dialectric end mirrors

[Monomorphic]

I was able to replicate the "predicted" TE012 in RFPlumber's frustum. The antenna shape is critical in this design to excite this mode. It cannot be replicated with a monopole or dipole antenna in that location.

However, I did not see TE012 at the "actual" frequency of 2.308Ghz.

[rfmwguy]

NASA Eagleworks Update - FYI only

About a month ago, I alluded to a brief email exchange with a member of NASA's Blue Ribbon Panel. There is no confidential information in it and I will keep that member's name private. Here is the relevant context of the email I received:

"As a member of the blue ribbon review panel, I am not allowed to make any public comments about the status or content of a committee report. Only NASA officials or designated representatives can issue public statements about any findings of the blue ribbon committee. My apology for not being able to state anything else.

Likewise, as a blue ribbon committee member, I am under an agreement not to issue any opinions of the project other than what is contained in the committee report once it has been released. (Until the report is released to the public I cannot make any comments.)"

In effect, this confirms that there is/was a panel and that they cannot mention anything prior to an official NASA release. This is why I stated that rumors would not be posted on NSF nor should they be taken seriously if found elsewhere as the key individuals are not going to pre-release information.

We continue to await details from official channels. In respect to this person's position, no further correspondence was initiated.

[Rodal]

  Monomorphic,

  If I'm not mistaken you were working on an optical EmDrive:

   https://www.reddit.com/r/EmDrive/comments/3p1atx/optical_em_drive/

  What happened to that project ?

The wavelength is much smaller in the optical range and the force predicted by all EM Drive theories should be much, much smaller in the optical range with a small micro-dimensioned  EM Drive.

See:

https://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347


Conversely if instead of using an EM Drive with very small micro dimensions, the plan was to use an EM Drive with dimensions similar to the ones built up to now, the mode shape would be extremely high at optical frequencies, and such very high modes are small amplitude. A FEKO simulation would show this.

  Thanks for the answer.
  If I'm not mistaken in Shawyer's theory/formula, the thrust doesn't depend on the wavelength, but it's proportional to:
     -the input power
     -the quality factor Q
  Since the input power is around 12W and Q is in the millions (according to the posts on Reddit), the resulting thrust should be even bigger than the one expected from the 2.45 GHz emdrives.

  Am I missing something here ?

P.S.:
  This is the thread where Q is discussed:

     https://www.reddit.com/r/EmDrive/comments/42uzo7/opticallaser_emdrive_revealed/

The interesting post is this:

Monomorphic 2 points 1 month ago

I calculated this a few months back. Q would be somewhere around 9,000,000 with the aluminum mirrors. ~70,000,000 with dialectric end mirrors

In the following post I dealt in detail with the force/InputPower and the Q for a number of theories, including Shawyer's theory:


https://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347

in that post I carefullly showed that the smaller the dimensions of the EM Drive the, smaller the Q, which is a well-known fact.  Furthermore, the smaller the EM Drive the smaller the field density which will translate into much smaller force/InputPower.  Conversely, if you one keeps the field density constant, the electromagnetic field magnitudes will be much greater and exceed electric breakdown  (since for constant density, the smaller the volume, the higher the field magnitude).  Electrical breakdown is a serious constraint in linear accelerators  electromagnetic cavities. It limits the electrical field strength, or gradient, which can be maintained in practice, and so, therefore, the power of such devices. (For many years, the design of cavities has been predicated on a semi-empirical formula known as the Kilpatrick criterion in order to address this problem. )

On the other hand, if the EM drive dimensions are kept comparable to present EM Drives, but a frequency in the optical range is used, the mode shape will be extremely high and it is well known that such high mode shapes are very low amplitude.

Briefly stated: I challenge the assertion that the Q will be 9 to 70 million and that there will be a significant force using optical frequencies.  Using a much higher frequency (in the optical range) is the wrong way to go according to all EM Drive theories, including Shawyer's theory.

[madsci]

Briefly stated: I challenge the assertion that the Q will be 9 to 70 million and that there will be a significant force using optical frequencies.  Using a much higher frequency (in the optical range) is the wrong way to go according to all EM Drive theories, including Shawyer's theory.

  Thanks for the detailed response.
  Just to clarify, Monomorphic's optical cavity has macroscopic dimensions (centimeters).

  Can you give an estimation of the order of magnitude of Q for such cavities ?
  Also, what theory/model/formula should be used for such an estimation ?

[Monomorphic]

I challenge the assertion that the Q will be 9 to 70 million and that there will be a significant force using optical frequencies.  Using a much higher frequency (in the optical range) is the wrong way to go according to all EM Drive theories, including Shawyer's theory.

You're probably right Dr. Rodal.  The optical/laser emdrive isn't theorized to operate according to RF frequency emdrive theories.  It is a separate theory I am working on independently.  That's why I tend not to talk about it much here, as this forum is more geared toward RF frequencies. I've also abandoned that other forum for the most part, so I doubt there will be any updates on the optical emdrive until after the interferometer test rig and my first shawyer-esque emdrive is completed and tested.

[Monomorphic]

  Can you give an estimation of the order of magnitude of Q for such cavities ?
  Also, what theory/model/formula should be used for such an estimation ?

This is what I used to estimate Q in an optical cavity.

[SeeShells]

I was able to replicate the "predicted" TE012 in RFPlumber's frustum. The antenna shape is critical in this design to excite this mode. It cannot be replicated with a monopole or dipole antenna in that location.

However, I did not see TE012 at the "actual" frequency of 2.308Ghz.

Very nice work monomorphic to question everything and examine all the frustum builds. Very smart.

If your FEKO calculations (your modeling has been outstanding so far) are correct, being off by 15MHz with his narrow band solid state amp would put him into a area where there was no mode of excitement and no energy being put into the frustum.
https://drive.google.com/folderview?id=0B3jbXEyEMvU8RmZGNk9pVF9GRk0&usp=drive_web
 
Good questions arise.

Shell

PS: I also think RFPlumber did a outstanding job at compiling and presenting his data and my comments are not in any way meant to take away from his DYI build or test, but I'm being a little like monomorphic here and question everything and look at everything.

[rfmwguy]

Hoping RFP will take another stab at it with all the interesting post-test analysis 

[Monomorphic]

I second Shells sentiment. We're not trying to tear anyone down and sincerely appreciate RFPlumbers work.

This is RFPlumber's second run listed in the paper. Same deal as before. Paper says he "verified its resonance modes with a scalar network analyzer."  So what we could be seeing here may be related to our previous discussions on tolerances. I'm simulating a perfect frustum, while RFP is measuring the modes in a crude frustum. Would be interesting to see the interior of the frustum. Is solder protruding like the exterior and changing the geometry?

[RonM]

I challenge the assertion that the Q will be 9 to 70 million and that there will be a significant force using optical frequencies.  Using a much higher frequency (in the optical range) is the wrong way to go according to all EM Drive theories, including Shawyer's theory.

You're probably right Dr. Rodal.  The optical/laser emdrive isn't theorized to operate according to RF frequency emdrive theories.  It is a separate theory I am working on independently.  That's why I tend not to talk about it much here, as this forum is more geared toward RF frequencies. I've also abandoned that other forum for the most part, so I doubt there will be any updates on the optical emdrive until after the interferometer test rig and my first shawyer-esque emdrive is completed and tested.

Since there isn't an accepted theory on EM drives, I think it is great that you are trying optical frequencies. I expect that you will not see any thrust, but we'll never know unless you give it a try. Data is needed to prove or disprove EM drives and a wide variety of experiments helps.

Keep up the good work.

[Rodal]

Briefly stated: I challenge the assertion that the Q will be 9 to 70 million and that there will be a significant force using optical frequencies.  Using a much higher frequency (in the optical range) is the wrong way to go according to all EM Drive theories, including Shawyer's theory.

  Thanks for the detailed response.
  Just to clarify, Monomorphic's optical cavity has macroscopic dimensions (centimeters).

  Can you give an estimation of the order of magnitude of Q for such cavities ?
  Also, what theory/model/formula should be used for such an estimation ?

1) Monomorphic stated that his proposed optical EM Drive is not based on any existing EM Drive theory, including Shawyer's "theory" :

You're probably right Dr. Rodal.  The optical/laser emdrive isn't theorized to operate according to RF frequency emdrive theories.  It is a separate theory I am working on independently.  That's why I tend not to talk about it much here, as this forum is more geared toward RF frequencies. I've also abandoned that other forum for the most part, so I doubt there will be any updates on the optical emdrive until after the interferometer test rig and my first shawyer-esque emdrive is completed and tested.

2) You ask about the Q for an EM Drive of similar dimensions as the ones tested up to now, but with an optical rather than a radio frequency excitation.

I have addressed the formulas involved in the aforementioned post

https://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347,

but let me address this physically here.

There is a huge dissonance between what has transpired in the last few pages of these threads and this question about a "Q" for such an optical EM Drive:

* on one hand we have TheTraveller (https://forum.nasaspaceflight.com/index.php?topic=39004.msg1502215#msg1502215) posting that Shawyer is stating that a tolerance 10 times the skin depth, or at 2.45 GHz,  10* 1.32 micrometers = 13 micrometers is needed to get 75% (https://forum.nasaspaceflight.com/index.php?topic=39772.msg1502318#msg1502318 ) of the theoretical Q at radio frequencies ~ 2.45 GHz, which have a free space wavelength of ~ 0.1224 m = 122 mm = 122,364 micrometers

So TheTraveller is stating that Shawyer is saying that the tolerance required is ~ 13 micrometers / 122,364 micrometers = 1/9413, about 1/10,000 of the wavelength.

At optical frequencies, of 500 THz, about 200,000 times greater frequency than 2.45 GHz, this means a tolerance requirement of 13/200,000 micrometers = 6.5*10^(-11) m = 65 picometers

So that you understand what this means: the picometre's length is of an order such that its application is almost entirely confined to particle physics and quantum physics. Atoms are between 62 and 520 pm in diameter, and the typical length of a carbon-carbon single bond is 154 pm.

Now, imagine that if to get 75% of theoretical Q at optical frequencies with an EM Drive of similar dimensions as presently tested, a tolerance equal to an atom's diameter, you will begin to understand the absurdity of getting anywhere close to such resonance in an actual device.  It would be practically impossible. 

The situation is worse: Monomorphic has accepted that he is aiming for a tolerance of only 1 mm.  There is no way that a resonance is going to be achieved at optical frequencies that have a wavelength 200,000 times smaller than the frequencies of a typical EM Drive.

There is no way that you are going to have reflection and resonance, with well-formed standing waves with a tolerance of only 1 mm at optical frequencies.

How can one have resonance in a cavity having 1 mm tolerance, with an optical wavelength of 0.0006 mm

Also think about the absurdity of discussing resonant mode shapes at such frequencies:  we are discussing mode shape TM212 for NASA's experiment at ~2 GHz and TE012 or TE013 for Shawer and Yang's experiments.  You would be discussing mode shapes with m and p orders of magnitude higher (m,n,p where TEmnp).

We have Monomorphic arguing whether RFMPlumber excited a very low frequency mode shape in his experiment.  Then, we cannot really simultaneously argue for the possibility of exciting optical mode shapes in an EM Drive of similar dimensions

I was able to replicate the "predicted" TE012 in RFPlumber's frustum. The antenna shape is critical in this design to excite this mode. It cannot be replicated with a monopole or dipole antenna in that location.



However, I did not see TE012 at the "actual" frequency of 2.308Ghz.

...

Since there isn't an accepted theory on EM drives, I think it is great that you are trying optical frequencies. I expect that you will not see any thrust, but we'll never know unless you give it a try. Data is needed to prove or disprove EM drives and a wide variety of experiments helps.

Keep up the good work.

Sorry, but there is complete dissonance in these latest pages 

A resonant frequency mode shape with m=thousand or hundreds of thousands ?

A Q in the millions with an optical EM Drive cm long and 1 mm tolerance ??

Q resonance in a cavity having 1 mm tolerance, with an optical wavelength of 0.0006 mm ??

*****

A laser inside a copper cavity that is cm long does not mean that you are going to get a resonance with "m" (in TEmnp) in the dozens of thousands and a Q in the millions.

If people are discussing whether a given mode shape was excited with cm wavelength at 2.45 GHz, what makes one think that they are going to be able to excite any significant resonance amplitude at optical frequencies?



 

[TheTraveller]

Latest email from Roger:

Hi Phil

... The Horizon programme will be transmitted in the UK at 20:00 on Wed 23 March. It is called Project Greenglow the search for gravity control.

Not sure how much reference to EmDrive there will be after it was reviewed by USAF and UK MOD.

Best regards

Roger

[Monomorphic]

How can one have resonance in a cavity having 1 mm tolerance, with an optical wavelength of 0.0006 mm [/b]

The 1mm tolerance is for the 2.45Ghz emdrive Dr. Rodal (though I hope to do better than that!). An optical emdrive would use optomechanical mounts to achieve MUCH higher tolerances (um). Optomechanical mounts are also very expensive. End plates are also purchased laboratory grade concave convex mirrors. It's a whole different beast... which is why I prefer not to talk about it here until after the TE311 Shawyer-esque build is completed. It's confusing as details are being mixed between the two.

[RonM]

...

Since there isn't an accepted theory on EM drives, I think it is great that you are trying optical frequencies. I expect that you will not see any thrust, but we'll never know unless you give it a try. Data is needed to prove or disprove EM drives and a wide variety of experiments helps.

Keep up the good work.

Sorry, but there is complete dissonance in these latest pages 

A resonant frequency mode shape with m=thousand or hundreds of thousands ?

A Q in the millions with an optical EM Drive cm long and 1 mm tolerance ??

*****

A laser inside a cavity that is cm long does not mean that you are going to get a resonance with m in the dozens of thousand and a Q in the millions

I've read page after page about resonant frequency mode shapes and while it is fascinating, does it really have anything to do with anomalous force in EM drives? One would think so if the anomalous force is anything other than unaccounted thermal effects. Then again, there may be something truly unusual going on here. Probably not, but the DIY experimenters here feel that it is worth their time and effort.

Monomorphic has a theory to test and it won't hurt anything to give it a shot.

Although, it would be a good idea to share the theory before building the device. Save time and effort if there are any issues with the theory.

[SeeShells]

Briefly stated: I challenge the assertion that the Q will be 9 to 70 million and that there will be a significant force using optical frequencies.  Using a much higher frequency (in the optical range) is the wrong way to go according to all EM Drive theories, including Shawyer's theory.

  Thanks for the detailed response.
  Just to clarify, Monomorphic's optical cavity has macroscopic dimensions (centimeters).

  Can you give an estimation of the order of magnitude of Q for such cavities ?
  Also, what theory/model/formula should be used for such an estimation ?

1) Monomorphic stated that his proposed optical EM Drive is not based on any existing EM Drive theory, including Shawyer's theory "theory" :

You're probably right Dr. Rodal.  The optical/laser emdrive isn't theorized to operate according to RF frequency emdrive theories.  It is a separate theory I am working on independently.  That's why I tend not to talk about it much here, as this forum is more geared toward RF frequencies. I've also abandoned that other forum for the most part, so I doubt there will be any updates on the optical emdrive until after the interferometer test rig and my first shawyer-esque emdrive is completed and tested.

2) You ask about the Q for an EM Drive of similar dimensions as the ones tested up to now, but with an optical rather than a radio frequency excitation.

I have addressed the formulas involved in the aforementioned post

https://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347,

but let me address this physically here.

There is a huge dissonance between what has transpired in the last few pages of these threads and this question about a "Q" for such an optical EM Drive:

* on one hand we have TheTraveller (https://forum.nasaspaceflight.com/index.php?topic=39004.msg1502215#msg1502215) posting that Shawyer is stating that a tolerance 10 times the skin depth, or at 2.45 GHz,  10* 1.32 micrometers = 13 micrometers is needed to get 75% (https://forum.nasaspaceflight.com/index.php?topic=39772.msg1502318#msg1502318 ) of the theoretical Q at radio frequencies ~ 2.45 GHz, which have a free space wavelength of ~ 0.1224 m = 122 mm = 122,364 micrometers

So TheTraveller is stating that Shawyer is saying that the tolerance required is ~ 13 micrometers / 122,364 micrometers = 1/9413, about 1/10,000 of the wavelength.

At optical frequencies, of 500 THz, about 200,000 times greater frequency than 2.45 GHz, this means a tolerance requirement of 13/200,000 micrometers = 6.5*10^(-11) m = 65 picometers

So that you understand what this means: the picometre's length is of an order such that its application is almost entirely confined to particle physics and quantum physics. Atoms are between 62 and 520 pm in diameter, and the typical length of a carbon-carbon single bond is 154 pm.

Now, imagine that if to get 75% of theoretical Q, a tolerance equal to an atom's diameter, you will begin to understand the absurdity of getting anywhere close to such resonance in an actual device.  It would be practically impossible. 

The situation is worse: Monomorphic has accepted that he is aiming for a tolerance of only 1 mm.  There is no way that a resonance is going to be achieved at optical frequencies that have a wavelength 200,000 times smaller than the frequencies of a typical EM Drive.

Also think about the absurdity of discussing resonant mode shapes at such frequencies:  we are discussing mode shape TM212 for NASA's experiment at ~2 GHz and TE012 or TE013 for Shawer and Yang's experiments.  You would be discussing mode shapes with m and p orders of magnitude higher (m,n,p where TEmnp).

How can we have rfmwguy and seeshells encouraging Monomorphic arguing whether RFMPlumber excited a very low frequency mode shape in his experiment and simultaneously argue for the possibility of exciting optical mode shapes in an EM Drive of similar dimensions.

Sorry, but there is complete dissonance in these latest pages 

My discussion is about the validity of a test and the possible error in a test with a frustum in the microwave mode, not monomorphic's testing of a optical cavity.

Consider these points.

I wondered when RFPlumber's test when he first ran his tests he deformed the large plate from heating.

I also wondered how a TE012 mode could provide the thermal profile on the large plate to warp it. It didn't match his COMSOL sim of a TE012.

Looking at the simulation of RFPlumbers done by monomorphic it just made sense that if he was off in the frequency that it would show up in the area of the highly modified loop antennas as a thermal profile and warp the endplate just like the FEKO image.

TT's spreadsheet doesn't show resonance and FEKO doesn't and I'm not sure if aero ran it in meep, so maybe could you run your numbers to see? Your maths calculated the mode frequencies agreeing with Frank Davis's COMSOL to a very high degree.

Shell

[Rodal]

...

Since there isn't an accepted theory on EM drives, I think it is great that you are trying optical frequencies. I expect that you will not see any thrust, but we'll never know unless you give it a try. Data is needed to prove or disprove EM drives and a wide variety of experiments helps.

Keep up the good work.

Sorry, but there is complete dissonance in these latest pages 

A resonant frequency mode shape with m=thousand or hundreds of thousands ?

A Q in the millions with an optical EM Drive cm long and 1 mm tolerance ??

*****

A laser inside a cavity that is cm long does not mean that you are going to get a resonance with m in the dozens of thousand and a Q in the millions

I've read page after page about resonant frequency mode shapes and while it is fascinating, does it really have anything to do with anomalous force in EM drives? One would think so if the anomalous force is anything other than unaccounted thermal effects. Then again, there may be something truly unusual going on here. Probably not, but the DIY experimenters here feel that it is worth their time and effort.
..

I answered a question I was asked about the Q quality of resonance for such a contraption, quoting somebody stating that the Q would be in 9 to 70 million for an EM Drive with similar dimensions as presently tested, but with optical rather than radio frequencies. The tolerance was quoted as ~ 1mm. That doesn't make sense.

Resonance of 9 to 70 million Q in a cavity that is cm long having 1 mm tolerance, with an optical wavelength of 0.0006 mm

If you can argue how can it make sense to have a Q of 9 to 70 millions with such a contraption, I am all ears. 

[RonM]

...

Since there isn't an accepted theory on EM drives, I think it is great that you are trying optical frequencies. I expect that you will not see any thrust, but we'll never know unless you give it a try. Data is needed to prove or disprove EM drives and a wide variety of experiments helps.

Keep up the good work.

Sorry, but there is complete dissonance in these latest pages 

A resonant frequency mode shape with m=thousand or hundreds of thousands ?

A Q in the millions with an optical EM Drive cm long and 1 mm tolerance ??

*****

A laser inside a cavity that is cm long does not mean that you are going to get a resonance with m in the dozens of thousand and a Q in the millions

I've read page after page about resonant frequency mode shapes and while it is fascinating, does it really have anything to do with anomalous force in EM drives? One would think so if the anomalous force is anything other than unaccounted thermal effects. Then again, there may be something truly unusual going on here. Probably not, but the DIY experimenters here feel that it is worth their time and effort.
..

I answered a question I was asked about the Q quality of resonance for such a contraption, quoting somebody stating that the Q would be in 9 to 70 million. That doesn't make sense.

If you can argue how can it make sense to have a Q of 9 to 70 millions with such a contraption, I am all ears.

I don't think a Q in the millions makes sense. Without seeing Monomorphic's theory we don't know the rational of the optical test, so we have to wait until the test is complete.

[Rodal]

If one googles "optical cavity" one can readily find arXiv and Nature articles on optical nanocavities ( (*)



an arrangement of mirrors that forms a standing wave cavity resonator for light waves) having high Q's > 10^5:  what is being discussed here is an EM Drive copper cavity that is  several centimeters long at optical frequencies, with 1 mm tolerance being able to have a Q >9 million.  Such optical nanocavities not relevant to the discussion of a several cm long copper cavity with mm tolerance.


_____

(*) or even what are considered "large" optical cavities: those larger than 4 μm

[madsci]

The situation is worse: Monomorphic has accepted that he is aiming for a tolerance of only 1 mm.  There is no way that a resonance is going to be achieved at optical frequencies that have a wavelength 200,000 times smaller than the frequencies of a typical EM Drive.

There is no way that you are going to have reflection and resonance, with well-formed standing waves with a tolerance of only 1 mm at optical frequencies.

How can one have resonance in a cavity having 1 mm tolerance, with an optical wavelength of 0.0006 mm

  As far as I understand, Monomorphic stated that his microwave frustum will have a tolerance (better than) 1mm, not the optical one.
  Most likely, the optical one will have optically aligned mirrors.
  Optical cavities can easily have Q of several millions, see:

     https://www.rp-photonics.com/q_factor.html

  Therefore, if we are to take Shawyer's theory as guide, it makes total sense that the thrust of an optical system with:
   -input power ~ 10W
   -quality factor > 1e6
will be easily measurable.

  Like RonM, I too think that the optical EmDrive is a legitimate path to explore, at least in light of what we know so far.
  Of course, there might be other arguments against an optical EmDrive, in this case, let's hear them.