Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1802430 times)

Offline aero

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Ok - I have a meep control file to share (coded in Scheme). Let me give pointers regarding Meep.

If you don't have Meep installed on your system, then compile it from source.  -- Here:
https://github.com/stevengj/meep/blob/master/src/meep.hpp#L169-L172
The binary installs available are not current with the documentation available and Meep source and documentation is updated often. Plus, there are some nice features recently added that are not available in the precompiled, binary downloads.

There are other interfaces to use instead of the Scheme language. Pick something else if you can use it. Scheme is hard to learn and code. The Python interface is well supported and the Meep native language is C++, here:
http://ab-initio.mit.edu/wiki/index.php/Meep_download

If you use Meep in your publications, be sure to include a proper cite.
http://ab-initio.mit.edu/wiki/index.php/Citing_Meep

The attached control file is fully enclosed, bare bones cavity. It models the Brady cavity in perfect metal using a constant dielectric. True copper behavior could be computed if I knew how to make a Drude model. Here is a Drude-Lorenz model for copper behavior at THz frequencies and above and there exist detailed explainations of how to convert the models to Meep parameters. It is finding the initial parameters in SI units that is my problem.

(define myCu (make dielectric (epsilon 1)
(polarizations
 (make polarizability
(omega 1e-20) (gamma 0.024197) (sigma 4.3873e+41))
(make polarizability
(omega 0.23471) (gamma 0.30488) (sigma 84.489))
(make polarizability
(omega 2.385) (gamma 0.85172) (sigma 1.395))
(make polarizability
(omega 4.2747) (gamma 2.5915) (sigma 3.0189))
(make polarizability
(omega 9.0173) (gamma 3.4722) (sigma 0.59868))
)))
;Additional Information
;Normalization length=1e-06 in meter
;Material_used_is_Cufrom Rakic et al.,Applied Optics (1998)
;Plasma Angular Frequency (and plasma wave vector,kp) in normalized units=6.6236


This material is easily used in Meep by the replacing the code (material metal) with (material myCu) and for our frequency a Drude model, (the first 6 lines) is good. There may even be a less complex (linear) model but the same difficulty holds, that of defining the imaginary coefficient of the dielectric behavior at 2 GHz. And I have the same problem with the HDPE dielectric disk; relating the loss factor to the imaginary coefficient of epsilon_sub_r.

Attached find images of the cavity, the stablized wave form (16 peroids with a very wide Gaussian noise bandwitth) and the control file. Replace the .txt extension with .ctl so Meep will recognize the control file. I have commented the control file in an attempt to share some lessons learned but of course I've missed some things. Ask, but read the comments first.

aero




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Offline SeeShells

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Forbes...
http://www.forbes.com/sites/investor/2015/05/29/investor-alert-emdrive-could-make-uber-seem-about-as-disruptive-as-a-sweat-smear/2/
The reason Iím writing this? If this force engine were to work, every industry you invest in will be turned upside down. Admittedly, this is a very early call.  Inventing a time machine would be more dramatic than EmDrive but not a lot more. A force engine would be like inventing fire.

Love the article Shell. History is full of disruptions, some natural, some forced. An example of forced disruption was: http://en.wikipedia.org/wiki/General_Motors_streetcar_conspiracy

What EMers are hoping for is natural, progressive disruption rather than forced, capitalistic disruptions like the interurban buyouts.
I like the fight between Thomas Edison's DC and Tesla's AC theories. Of course we all know Tesla won out in the end, but the advancement of mankind using AC was very disruptive. It only left a footnote in our history but we're still reaping the benefits of Tesla's genius. I wonder if Tesla was living what would he think of the EM Drive? Would Einstein say "oh das even spookier'!  :o

We have some very very smart people in the world today and naming them one by one I soon run out of fingers and toes and every bit as smart as Tesla, Einstein or the score who laid down our understanding of physics. The thing that's different is there is so much basic data, it's not like we are trying to define what makes a glass gar wrapped in metal foil hold a charge. Fields and projects like this require an intimate knowledge in almost all endeavors of science, science that's grown exponentially through the years. 

To have a site like this that enables the best minds to interact in various fields they excel in is like Brain Funding and I'm glad it's here.

Offline SeeShells

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...Actually a photon rocket is not really "propellantless" as it throws away photons. We could say that its exhaust is "pure energy" (in the sense that the exhaust particles have no rest mass), ...

CoE difference (between photon rocket and EM drive) appears clearly when comparing behaviour at relativistic speeds, it needs high mass->energy conversion yield and low payload fraction to reach 2/3 light speed with photon rocket. Should the payload at 2/3 light speed hit a rock, the mass equivalent of released energy couldn't possibly be higher than the mass "burnt" to energy during acceleration. This inequality is built in, from the ground up. EM drive proponents (Shawyer, White) sell us spacecraft that could reach 2/3 light speed on fission reactors, with high payload fraction where only a few % of initial mass (at most) was burnt to energy, and when hitting a rock at final velocity release an energy with a mass equivalent much much higher than the mass burnt. Then they say, by the way this must be respecting CoE, and introduce some (as yet to be clearly defined) penalty against some mysterious "gained velocity", not intrinsically built in from the ground up but after the fact as an ad hoc inequality, and what is more scandalous fail to caution (or care) that this little caveat was not used at all when setting up mission profiles that do clearly get us to more energy than was put in. If one is to be taken seriously, one can't say "this is respecting CoE" in one chapter, and say "this could go up to 2/3 light speed on nuclear reactor" the next chapter. This is like saying that x<10 in a preamble, developing other equations showing that x=100, and concluding that is is so great to have x=100 and that everything is fine since x<10. And then when people complain, argue that x needs special treatment, that its values is nothing like we knew before... Grumble, growl, moan...
I wonder if some realize how much power is in the atom. If I convert the mass of a just a dollar bill into energy I have the equivalent energy released in the first atomic bomb. ~63 TJ

Offline aero

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Some time ago I promised Dr. Rodal that I would gather collected papers on evanescent waves to post. I finally found where I had squrreled away the link to a key reference, so here is the list. You've seen parts of some of these papers, but the full paper goes much further than anyone can with just a blog post.

http://arxiv.org/pdf/1308.0547.pdf See Supplimentary Table 1.
http://arxiv.org/pdf/0712.0347.pdf
http://wwwsis.lnf.infn.it/pub/INFN-FM-00-04.pdf I like Appendix B
http://arxiv.org/pdf/1211.0530v2.pdf This one just hints at our situation.
http://bit.ly/1Ja6QLV Again, hints
http://tuttle.merc.iastate.edu/ee439/topics/tunneling.pdf Tunneling and evanescent wave math are very similar.
http://en.wikipedia.org/wiki/Maxwell_stress_tensor Not quite sure why this is here, maybe the stress-energy tensor derivation?

Happy researching.
« Last Edit: 05/30/2015 07:33 PM by aero »
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Offline deltaMass

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Quote from: SeeShells
Would Einstein say "oh das even spookier'!  :o
Probably something like
"spukhafte Statischwirkung"

Offline aero

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Here is a shortened URL

http://bit.ly/1Ja6QLV

to that humongous URL that is screwing up the page formatting here http://forum.nasaspaceflight.com/index.php?topic=37642.msg1382092#msg1382092

Could you please change it to this shortened one ? so as to recover the original page formatting?

Thanks  :)

Done, but the attachment still contains the long one. The one attached here has the short one.
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Offline SeeShells

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Ok - I have a meep control file to share (coded in Scheme). Let me give pointers regarding Meep.

Attached find images of the cavity, the stablized wave form (16 peroids with a very wide Gaussian noise bandwitth) and the control file. Replace the .txt extension with .ctl so Meep will recognize the control file. I have commented the control file in an attempt to share some lessons learned but of course I've missed some things. Ask, but read the comments first.

aero
Aero, your name is very close to Hero. Nice job!

Offline aero

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Ok - I have a meep control file to share (coded in Scheme). Let me give pointers regarding Meep.

Attached find images of the cavity, the stablized wave form (16 peroids with a very wide Gaussian noise bandwitth) and the control file. Replace the .txt extension with .ctl so Meep will recognize the control file. I have commented the control file in an attempt to share some lessons learned but of course I've missed some things. Ask, but read the comments first.

aero

Aero, your name is very close to Hero. Nice job!

I think A is a whole octave before H.  :)
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Offline SeeShells

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Ok - I have a meep control file to share (coded in Scheme). Let me give pointers regarding Meep.
 Ask, but read the comments first.

aero
I've been working to get meep up and going and this answers some basic questions. I think I'm going to do fine. Thanks for the fine work.
PS: Trying to get it up and working, my head exploded.
http://ribkit.sourceforge.net/sler/images/screenshots/sler-v0.1alpha.jpg

Offline Rodal

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« Last Edit: 05/30/2015 10:14 PM by Rodal »

Offline davish

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Oh Baby, here is a test stand floating on air, ready for baby EM drive   :)
...

Is this "baby" EM Drive supposed to have lower thrust according to any of the theories? Or is thrust completely based on resonance?
« Last Edit: 05/30/2015 08:51 PM by davish »

Offline Rodal

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Oh Baby, here is a test stand floating on air, ready for baby EM drive   :)
...

Is this "baby" EM Drive supposed to have lower thrust according to any of the theories? Or is thrust completely based on resonance?

Some theories have thrust inversely proportional to frequency (hence this one at 24 GHz should have ~10 times less thrust than the ones at 2.4 GHz so far tested, based on inverse of linear proportionality alone)

McCulloch's formula  F = PQl/c * (1/w_small - 1/w_big) where l is the cavity length is independent of frequency.  But it is still proportional to power input.

Most theories have thrust proportional to PowerInput  This just has a little battery, so also have to factor out less thrust due to the lower Power Input

So, yes, substantially less thrust, according to those theories.

Higher frequency also means more geometrical attenuation, perhaps that's good, if it also has higher Q to go with it

And you can put a lot of these ones together, and it looks much neater and Hi-Tech  :)

If it works, it can go right away into a CubeSat
« Last Edit: 05/31/2015 02:57 PM by Rodal »

Offline davish

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Some theories have thrust inversely proportional to frequency (hence this one at 24 GHz should have ~10 times less thrust than the ones at 2.4 GHz so far tested, based on inverse of linear proportionality alone)
...
And you can put a lot of these ones together, and it looks much neater and Hi-Tech  :)

If it works, it can go right away into a CubeSat

So with the most optimistic figures from the Chinese, a thruster like this could get 72 mN of thrust with 2.5 kW of power, which is obviously way too much power for a CubeSat. If you had, say, four of these baby EM Drives on a CubeSat, would it be a practical propulsion method for getting from LEO to somewhere else, or just for maintaining an orbit in LEO (which would be impressive in its own right)?

Offline kitsuac

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Sorry for my novice question - but is it considered within the realm of physical possibilities that a gravity well is being created (or shifted?) such that the device falls into it rather than being thrusted toward it? If it is remotely feasible, could an experimenter rule it out or confirm by placing a second object on a scale above the device to see if it also falls into the gravity well?

I'm well out of my depth, in spite of endless hours spent trying to gain some small understanding of modern physics, but it's refreshing to see all of this detailed discussion going on in an open forum, where the science is given priority over profit motives and secrecy. It'd be nearly as interesting to eventually find what sort of "boring" explanation may have so far alluded so many bright minds, as it would be to find some significant scientific understanding requiring revision.

Offline aero

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Ok - I have a meep control file to share (coded in Scheme). Let me give pointers regarding Meep.
 Ask, but read the comments first.

aero
I've been working to get meep up and going and this answers some basic questions. I think I'm going to do fine. Thanks for the fine work.
PS: Trying to get it up and working, my head exploded.
http://ribkit.sourceforge.net/sler/images/screenshots/sler-v0.1alpha.jpg

A lot of professional Meep users also use ParaView to look at the data. If you have a few spare braincells left, ... Well, here is the link. http://www.paraview.org/

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Offline rfmwguy

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Sorry for my novice question - but is it considered within the realm of physical possibilities that a gravity well is being created (or shifted?) such that the device falls into it rather than being thrusted toward it? If it is remotely feasible, could an experimenter rule it out or confirm by placing a second object on a scale above the device to see if it also falls into the gravity well?

I'm well out of my depth, in spite of endless hours spent trying to gain some small understanding of modern physics, but it's refreshing to see all of this detailed discussion going on in an open forum, where the science is given priority over profit motives and secrecy. It'd be nearly as interesting to eventually find what sort of "boring" explanation may have so far alluded so many bright minds, as it would be to find some significant scientific understanding requiring revision.

Welcome to the em-think tank...good thought, closest test was a laser test in chamber which I think showed bending. Search thread 2 for "laser" to dig out more specifics.

Also here http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/
« Last Edit: 05/31/2015 12:17 AM by rfmwguy »

Offline zen-in

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Some theories have thrust inversely proportional to frequency (hence this one at 24 GHz should have ~10 times less thrust than the ones at 2.4 GHz so far tested, based on inverse of linear proportionality alone)
...
So, yes, substantially less thrust, according to those theories.

Higher frequency also means more geometrical attenuation, perhaps that's good, if it also has higher Q to go with it

And you can put a lot of these ones together, and it looks much neater and Hi-Tech  :)

If it works, it can go right away into a CubeSat

Much, much safer than playing around with a magnetron or other high power RF source.

Offline Notsosureofit

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Oh Baby, here is a test stand floating on air, ready for baby EM drive   :)

The whole system in one neat package floating on air (magnetically) (Watch out for leaking external field interaction ??? )


Well, if they get it together, I can put that one into a working vacuum system tomorrow !!
« Last Edit: 05/31/2015 12:57 AM by Notsosureofit »

Offline Rodal

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Oh Baby, here is a test stand floating on air, ready for baby EM drive   :)

The whole system in one neat package floating on air (magnetically) (Watch out for leaking external field interaction ??? )


Well, if they get it together, I can put that one into a working vacuum system tomorrow !!
The guy doing this lists himself as being in Aachen.  Aachen has pretty much the top Aerospace University program in Germany.  It is very interesting that he is not just replicating what Shawyer or the Chinese did, but he is going his own very innovative way: with a baby EM Drive operating at 10 times higher frequency, using a modified radar module as the frequency source.   All in a self-contained unit powered by a small battery and tested on a floating on air device.  He has also disclosed that he run a numerical model of the baby EM Drive resonance frequency (to make sure that it resonates at an undisclosed mode shape at 24 GHz) prior to his friend doing the machining.

Somebody wrote to him (in his Blog) that it had been pointed out in this NSF thread that ammonia gas was used in early Masers because ammonia gas emits at 24 GHz and he responded that he found that very interesting.
« Last Edit: 05/31/2015 01:49 AM by Rodal »

Offline deltaMass

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Pardon my naive nonplussedness, but why would the Aachen guy stating that he found ammonia's masing frequency interesting - be interesting? :)

Well, let's first see if it works.
« Last Edit: 05/31/2015 03:30 AM by deltaMass »

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