Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797588 times)

Online flux_capacitor

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High power for DIYers: eBay is a goldmine for magnetrons. See for example this compact CW, 2kW, 2.45GHz Hitachi 2M130 magnetron fitted in a water-cooled C12139-1 assembly, on sale in the US for $65.
Product technical specs available:
http://www.2450mhz.com/PDF/Doc/900022.PDF
Also a very precise magnetron data sheet:
http://www.rell.com/filebase/en/src/Datasheets/2M130-spec.pdf



Besides, ~1kW magnetrons are even cheaper, between 20 and 50 bucks.

Travelling Wave Tube (TWT) amplifiers should also be considered, as they also offer high power and wide bandwidth of operation, although at a slightly higher price.

SECURITY EDIT: At those powers don't forget the cage, always. Michael protects you since 1836
« Last Edit: 06/29/2015 03:31 PM by flux_capacitor »

Offline aero

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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 ?

Yes, exactly that one. Or at least that is the basis for my calculations.
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Offline saucyjack

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All-  To make it easier to search past threads, @Chris Bergin has given me permission to copy the contents of the locked forum threads 1 and 2 onto http://emdrive.wiki - see links at the bottom.  I will do the same for thread 3 when it's locked and we graduate to thread 4.

Each page takes a bit of time to render given the many external photos linked off, but the wiki Search function in the upper right, combined with "Control-F" within the page, should make it a lot to review previous posts.  I find it fascinating that these threads actually began way back in 2012.

Online Rodal

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All-  To make it easier to search past threads, @Chris Bergin has given me permission to copy the contents of the locked forum threads 1 and 2 onto http://emdrive.wiki - see links at the bottom.  I will do the same for thread 3 when it's locked and we graduate to thread 4.

Each page takes a bit of time to render given the many external photos linked off, but the wiki Search function in the upper right, combined with "Control-F" within the page, should make it a lot to review previous posts.  I find it fascinating that these threads actually began way back in 2012.

Thanks for doing this to facilitate searching of the threads.

Could you please lock the searchable NSF EM Drive threads in the wiki so that people are not able to edit and modify them?  (people should be able to just view them and search them, the "Edit" page should not be available, particularly when it comes to modifying other people's comments).

The way it is now, it looks like anyone can come and edit at will these  NSF EM Drive threads in the wiki (I just tried and was able to access the Edit page of the searchable threads without trouble)
« Last Edit: 06/29/2015 03:40 PM by Rodal »

Offline saucyjack

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...

Could you please lock the searchable NSF EM Drive threads in the wiki so that people are not able to edit and modify them?  (people should be able to just view them and search them, the "Edit" page should not be available, particularly when it comes to modifying other people's comments).

The way it is now, it looks like anyone can come and edit at will these  NSF EM Drive threads in the wiki (I just tried and was able to access the Edit page of the searchable threads without trouble)

Good idea, these pages are both locked down now.

Online 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?
As a practical example of using Saucyjack's incorporation of the NSF threads into the EM Drive wiki to make them searchable, I looked for "Axions", and I immediately found this great post by Astrophysicist TMEubanks   (lots of information in a few lines):


Title: Re: EM Drive Developments - related to space flight applications - Thread 2
Post by: TMEubanks on 02/15/2015 06:30 PM
Thoughts on Axions. (I apologize if this has been already covered.)

The question as to whether the EM Drive could be coupling to the Axion background came up on a different forum. I am dubious, and thought it would be useful to post why.

A recent review of axions as CDM: http://www.pnas.org/.../2015/01/07/1308788112.full.pdf

Current constraints on the axion mass constrain it to be in the range ~ 1 - 1000 micro-eV, and a 2 GHz axion would correspond to 8.2 micro-eV, so that's OK, maybe the EM drive couples to the axion mass. But, check out the Axion Dark-Matter Experiment in the PNAS article. That is much much more sensitive than the EM Drive - they are looking for yoctowatts (10^-24) of RF power in the 2 - 20 micro-eV range, precisely the range of the EM Drive, by tuning the cavity's resonant frequency to the axion mass. There is simply no way that the Drive is coupling to the axion background - the ADMX would see a whopping signal. Now, maybe the ADMX is producing lots of axions, at a low enough velocity to evade the photon rocket limits. That would mean that the EM Drive can convert watts of RF -> axions, while the ADMX is NOT converting 10^-24 watts of dark matter axions -> RF power. While I guess it is possible, I just don't buy it. Nobody is accidentally lucky by 20+ orders of magnitude. (Note also that the theory is pretty clear here - if axions have these kinds of 1 - 10 micro-eV masses, they will supply most or all of the DM, so there will be a background.)
« Last Edit: 06/29/2015 04:19 PM by Rodal »

Offline SeeShells

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rfmwguy hit up on the idea of using a helical antenna and it fit into my ideas of how the frustum works. But... I was having issues with running 800-1000 watts of magnetron 2.45 Ghz energy into it. I'd looked at it before. It wasn't only the helical design that I was pursuing, it was a tapered bifilar helical antenna. Several reasons I like the design is it's compact and it gave me the rotating waveform I was looking for. http://www.antennamagus.com/database/antennas/220/bifilar_helix_antenna_design.png
The issue with it is it needs a ground plane and a ground plane within the Frustum cavity would be a mistake from several standpoints.
So I've been looking to do a modified one and if done right removes the need to use a reflective ground plane. I'm looking at a conical shaped bifilar helical antenna.
http://www.intechopen.com/books/advances-in-satellite-communications/helical-antennas-in-satellite-radio-channel

This is a little beyond a simple dipole I'm afraid, but gives me the ability to increase gain, removes the need for a ground plane, allows the focus the frontal lobe of the pattern into the small end of the cavity and endplate (increase of ~12db) thereby increasing the stored mode energy and there after the power pulse release effect we have seen in the simulation videos. The real plus I believe is the circulating polarized waveform generation for the evanescent wave out the large end of the Frustum cavity.
http://www.fpvuk.org/wp-content/uploads/2012/06/circular.png

Shell

PS: Still working out the basics rfmwguy and you are one sharp guy to grasp so quickly what I'd been mulling over for over a week.

PSS: Back to reading and pushing a pencil on some numbers to build this crazy antenna. I wish my ex was still with us (sharp sharp man) as he'd go, oh that's easy Shell... watch this. And then I'd feel real stupid. lol

PSSS: Go for the POWER rfmwguy, go to Goodwill buy a $10 dollar microwave, strip it, pull out the PS and magnetron. Get out of the noise and internal loss. If that doesn't work for both of us, consider chipping in together, buy a Klystron from ebay and enjoy the visual of slag. ;)

Offline aero

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Longitudinal Animation



Great videos - Could you please make videos of two files located here:
    frmwguy - ez - xyz views / fixed color range Ez views / Two files Ez-x, Ez-y

Those are the only two files of their kind on the drive. They show how the energy stored in high Q the cavity increases as cycles of drive power are added at resonance. Although the drive frequency may not exactly be at resonance, in this case there is Gaussian noise which inputs some power at the resonant peak. Energy accumulates and the color definition increases as the run progresses. This is not the best way to show relative flux within the cavity but at this time, it is the only way we have.

This is to differentiate from the behaviour of the cavity energy when the drive frequency contains no noise and is not quite on resonance. Examples of this situation are currently being uploaded and will be available in a few hours.
       
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Offline zen-in

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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.

Did anybody here tried to increase the vibration in order to increase thrust? I would be glad to check that as well :).

...

Link is here. The claim is in lower half of the thread.
https://www.reddit.com/r/EmDrive/comments/3ah1ta/using_thetravellers_excel_emdrive_calculator/

Thank you :)
A claim is made based solely on what supposedly Shawyer said.

The magnitude and frequency of the vibration that facilitates the measurement of the EM Drive is never addressed.

Is the EM Drive an equal opportunity friend of all magnitudes and frequencies of vibration?   This is implied, but it leads to absurd nonsense: is nanometer amplitude vibration enough ? How about picometer amplitude vibration?  At what level the boundary between vibration in continuum mechanics and quantum mechanics uncertainty is breached ?

How about frequency?  Is 100 Hz sufficient? How about 0.0000000001 Hz? How about 10^100 Hz?

...

Statements like this serve to explain the controversy surrounding the EM Drive, and why it has made so little progress (despite the extravagant claims) in the 27 years (almost 3 decades) since Shawyer's 1988 patent application.  A scientific approach is needed instead.  Hopefully we will hear more news from NASA soon or get independent experimental data from well-constructed tests from the people in this thread.

One note I would like to add on this subject:   If Shawyer's em-drive does not produce any thrust in the absence of vibration then it will not work in outer space.    Space is a vacuum and sound waves don't travel in space.   There would be no vibrations to "stimulate" the em-drive.   

Offline SeeShells

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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.
Microwaves can be highly focused and reflected. I'm even leary of cell phones. But more than considering what's in the faraday cage getting out, you need to consider keeping the outside interference from getting in. Plus, if you select a fine enough screen (copper screen from the hardware works well) it also helps with air circulation issues. So any power level is a smart move for a faraday cage.

Shell

Edit, like rfmwguy I ned to fex stoopind speeling, and if you can read that you're mucked up too. :)
« Last Edit: 06/29/2015 04:45 PM by SeeShells »

Offline DrBagelBites

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Microwaves can be highly focused and reflected. I'm even leary of cell phones. But more than considering what's in the faraday cage getting out, you need to consider keeping the outside interference from getting in. Plus, if you select a fine enough screen (copper screen from the hardware works well) it also helps with air circulation issues. So any power lever is a smart move for a faraday cage.

Shell

Was planning on just recording noise before testing, but you have a good point. Will look further into copper screen.

-I

Offline SeeShells

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Doing research on a cone spiral wound antenna i ran across one of my childhood heroes designs, using a cone shape. I wish I could pick his brain right now, it would be interesting.
Shell
http://www.villesresearch.com/images/teslacone.jpg
http://nikolatesla-inventor.com/INVENTIONS/index.html

Offline SeeShells

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A claim is made based solely on what supposedly Shawyer said.

The magnitude and frequency of the vibration that facilitates the measurement of the EM Drive is never addressed.

Is the EM Drive an equal opportunity friend of all magnitudes and frequencies of vibration?   This is implied, but it leads to absurd nonsense: is nanometer amplitude vibration enough ? How about picometer amplitude vibration?  At what level the boundary between vibration in continuum mechanics and quantum mechanics uncertainty is breached ?

How about frequency?  Is 100 Hz sufficient? How about 0.0000000001 Hz? How about 10^100 Hz?

...

Statements like this serve to explain the controversy surrounding the EM Drive, and why it has made so little progress (despite the extravagant claims) in the 27 years (almost 3 decades) since Shawyer's 1988 patent application.  A scientific approach is needed instead.  Hopefully we will hear more news from NASA soon or get independent experimental data from well-constructed tests from the people in this thread.

One note I would like to add on this subject:   If Shawyer's em-drive does not produce any thrust in the absence of vibration then it will not work in outer space.    Space is a vacuum and sound waves don't travel in space.   There would be no vibrations to "stimulate" the em-drive.
Very well said. Each and every one of us that's trying to do their best with the resources at hand to build a EMDrive, but also build it as the best valuable scientific tool they can. With the help of some very smart and driven people that would love to see it work. Even better are the ones who would love to open up the "can-o-worms physics" as to why and how it works. It's a win/win even if it fails.  In how it's fooled some very brilliant people with some weird action in a not so obvious abnormality.

Offline SeeShells

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Microwaves can be highly focused and reflected. I'm even leary of cell phones. But more than considering what's in the faraday cage getting out, you need to consider keeping the outside interference from getting in. Plus, if you select a fine enough screen (copper screen from the hardware works well) it also helps with air circulation issues. So any power lever is a smart move for a faraday cage.

Shell

Was planning on just recording noise before testing, but you have a good point. Will look further into copper screen.

-I
A easy way to put some screen is to use a piece of stiff chicken wire to tie off the fine screen to. FWIW.

Shell

Offline aero

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Views of NSF-1701 are up:

https://drive.google.com/folderview?id=0B1XizxEfB23tfklENXg2TWhrbUhneGxZQzJ0VVhkRFRwUUhCN2xKX24yOGM2bFQzdVV5NlE&usp=sharing

This file shows the 18 views of the E and H components from x, y and z directions.
This is from a Meep model of rfmwguy's 10.2 inch cavity, in copper, driven by a 2.45000 GHz continuous Ez source. The resonant frequency of this cavity is somewhere close to 2.45 GHz but no resonance solutions indicate exactly 2.45 GHz. The continuous source used in this model is ideal and exact. There are no "shoulders" on the input power source, all input energy is at exactly the drive frequency, 2.45 GHz. The antenna model, a dipole, is oriented perpendicular to the central axis of rotation, one-half wavelength from the small end, and is 0.058 meters long.

An important point is to note that these views use a fixed Max/Min range of power/color intensity. I'll leave it to the experts to analyse the characteristics shown.

« Last Edit: 06/29/2015 06:27 PM by aero »
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Offline Ricvil

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Thank you for your answers.
 I just want explain my point of view, and I will not write more comments at all. :) In fact, all experiments until now are trying to detect the axion by converting it into few photons and then detect that few photons signatures by resonant cavitys and interferometers.
 I'm not trying detect then, but i want see a huge effect from a few ones.
Trying to explain the net force using only conventional electromagnetic theory can be more difficult because the emdrive cavity is closed, and net force/tension caused by reflections of photons momentuns tend be zero by the momentum conservation laws.
 The way to produce a net force will be only if something carries momentum out of cavity.
The coupling with axion field with photons is very small in theory, but the article i had cited opens a window for a huge collective interaction, between a small axion field ( "small polarizable scatter") and the electromagnetic modes propagating inside cavity.
The article talks about a total reflection of waves inside waveguide ( total reverse of momentum of photons) by a "arbitrarily small polarizable scatter". This implies on a huge radiation pressure on the scatter (the axion) . At the axion electrodynamic point of view, the small axion field will acting like a "topological insulator" scatter.
A simple numeric simulation can show if the effect is mensurable at the critical frequency of ressonating backscattering.
 The cavity, under mirror simmetry of the taps, can be thought as a corrugated waveguide with triangular cross section profile, and an modal analysis can show the critical frequency pointed by the article ( near the frequency of the second propagating mode of waveguide). To produce the axion field on cavity, the fundamental mode must be a hybrid mode (E.B <>0 is the source of axion field at the equations), but this can occurs because the image of cavity is a corrugated waveguide to the internal em fields.
Inside cavity, there are at least two counter propagating modes, but the gradient of fields distribuition and the positon of the source can make the scatter process to be asymmetrical.
 I think could be very interesting to simulate the axion electrodynamic for the emdrive geometry and frequencys, and see if/when the ressonant backscattering conditions are satisfied. Thank you guys.

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?
As a practical example of using Saucyjack's incorporation of the NSF threads into the EM Drive wiki to make them searchable, I looked for "Axions", and I immediately found this great post by Astrophysicist TMEubanks   (lots of information in a few lines):


Title: Re: EM Drive Developments - related to space flight applications - Thread 2
Post by: TMEubanks on 02/15/2015 06:30 PM
Thoughts on Axions. (I apologize if this has been already covered.)

The question as to whether the EM Drive could be coupling to the Axion background came up on a different forum. I am dubious, and thought it would be useful to post why.

A recent review of axions as CDM: http://www.pnas.org/.../2015/01/07/1308788112.full.pdf

Current constraints on the axion mass constrain it to be in the range ~ 1 - 1000 micro-eV, and a 2 GHz axion would correspond to 8.2 micro-eV, so that's OK, maybe the EM drive couples to the axion mass. But, check out the Axion Dark-Matter Experiment in the PNAS article. That is much much more sensitive than the EM Drive - they are looking for yoctowatts (10^-24) of RF power in the 2 - 20 micro-eV range, precisely the range of the EM Drive, by tuning the cavity's resonant frequency to the axion mass. There is simply no way that the Drive is coupling to the axion background - the ADMX would see a whopping signal. Now, maybe the ADMX is producing lots of axions, at a low enough velocity to evade the photon rocket limits. That would mean that the EM Drive can convert watts of RF -> axions, while the ADMX is NOT converting 10^-24 watts of dark matter axions -> RF power. While I guess it is possible, I just don't buy it. Nobody is accidentally lucky by 20+ orders of magnitude. (Note also that the theory is pretty clear here - if axions have these kinds of 1 - 10 micro-eV masses, they will supply most or all of the DM, so there will be a background.)




Offline X_RaY

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Views of NSF-1701 are up:

https://drive.google.com/folderview?id=0B1XizxEfB23tfklENXg2TWhrbUhneGxZQzJ0VVhkRFRwUUhCN2xKX24yOGM2bFQzdVV5NlE&usp=sharing

This file shows the 18 views of the E and H components from x, y and z directions.
This is from a Meep model of rfmwguy's 10.2 inch cavity, in copper, driven by a 2.45000 GHz continuous Ez source. The resonant frequency of this cavity is somewhere close to 2.45 GHz but no resonance solutions indicate exactly 2.45 GHz. The continuous source used in this model is ideal and exact. There are no "shoulders" on the input power source, all input energy is at exactly the drive frequency, 2.45 GHz. The antenna model, a dipole, is oriented perpendicular to the central axis of rotation, one-half wavelength from the small end, and is 0.058 meters long.

An important point is to note that these views use a fixed Max/Min range of power/color intensity. I'll leave it to the experts to analyse the characteristics shown.

Amazing work aero!
It looks a little bit out of phase, there are fluctuations during this thing is oscillating..
« Last Edit: 06/29/2015 07:21 PM by X_RaY »

Offline smartcat

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I am not a Shawyer fan but the Traveller defense could be not so crazy, look at the following paper:

Motion induced radiation from a vibrating cavity
http://arxiv.org/abs/quant-ph/9606029

We study the radiation emitted by a cavity moving in vacuum. We give a quantitative estimate of the photon production inside the cavity as well as of the photon flux radiated from the cavity. A resonance enhancement occurs not only when the cavity length is modulated but also for a global oscillation of the cavity. For a high finesse cavity the emitted radiation surpasses radiation from a single mirror by orders of magnitude.
Amazing!.. Is this IT then?!

The paper is referring to the Dynamic Casimir effect, which has required a SQUID to produce the effect experimentally.  The copper walls of the EM Drive are not moving anywhere close to the required speed.

Here is a mechanical device with high Q that has mechanical vibration in the GHz range:  http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.152.4917&rep=rep1&type=pdf

see how much smaller than the EM Drive's tested by researchers it is:

 20m-diameter = 14,000 times smaller diameter than the EM Drive
 2m-stem

stem offset from the center by only 1m

@Rodal:

The reason I was excited was that there is apparently a way to generate photons "out of space" with GHz mechanical vibrations, and I thought the frustum could perhaps be optimized for that (the energy coming from the EM field at such f), and perhaps the internal fields could also perform the "magic" of either directing the generated photons, or making their generation directional, thereby just transferring momentum in one direction by the photons hitting one end in-elastically, without the frustum experiencing a reaction force during generation or directing - hence magic.

As the inventor claims one needs vibrations (though not at GHz level) to get the thing start moving. So I felt there was a remarkable match between the two setups. I cannot work out any details unfortunately. :-[
« Last Edit: 06/29/2015 10:40 PM by smartcat »

Online A_M_Swallow

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One note I would like to add on this subject:   If Shawyer's em-drive does not produce any thrust in the absence of vibration then it will not work in outer space.    Space is a vacuum and sound waves don't travel in space.   There would be no vibrations to "stimulate" the em-drive.   


Attaching a vibrator to the drive is not hard.

Although when the press finds out the spacecraft needs a vibrator to come we will get lots of dildo jokes.

Online Rodal

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Views of NSF-1701 are up:

https://drive.google.com/folderview?id=0B1XizxEfB23tfklENXg2TWhrbUhneGxZQzJ0VVhkRFRwUUhCN2xKX24yOGM2bFQzdVV5NlE&usp=sharing

This file shows the 18 views of the E and H components from x, y and z directions.
This is from a Meep model of rfmwguy's 10.2 inch cavity, in copper, driven by a 2.45000 GHz continuous Ez source. The resonant frequency of this cavity is somewhere close to 2.45 GHz but no resonance solutions indicate exactly 2.45 GHz. The continuous source used in this model is ideal and exact. There are no "shoulders" on the input power source, all input energy is at exactly the drive frequency, 2.45 GHz. The antenna model, a dipole, is oriented perpendicular to the central axis of rotation, one-half wavelength from the small end, and is 0.058 meters long.

An important point is to note that these views use a fixed Max/Min range of power/color intensity. I'll leave it to the experts to analyse the characteristics shown.

Since we continue with images shown without displaying any numerical values associated with them, we have to resort to some heuristic as following to interpret these pictures:

1) Pictures showing fractals are a numerical artifact due to values close to zero, hence pictures with fractals should be interpreted as low values close to zero

2) Concentrate on images showing smooth and persistent contours (persistent in several frames)

3) Use the field in the longitudinal x direction to determine mode shape

4) Conduct independent eigenvalue analysis to determine frequencies of several modes with the same dimensions (L=10.2 inches in this case) to ascertain nearby mode participation.


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

Using the above-mentioned heuristics, we determine:

1) The strong field in the longitudinal x direction is Ex, in this case Ex -y (the electric field in the longitudinal direction, seen in the x-z plane with normal y).  This field shows 4 wave patterns in the longitudinal direction.  Hence p=4.  Notice that Ex - z is zero.



2) Hx  -y and Hx -z are fractal hence interpreted as close to zero

3) Actually all magnetic fields in this case appear to be fractal, hence interpreted as very low, close to zero

4) Ez is strong both in the planes with y and z normals.  Both show p=4





5) The strong Ex points towards a TM mode.  The lack of any strong H field in the transverse directions points towards a TE mode

6) How can that be?  An examination of the eigenvalue problem using Mathematica and the exact solution shows:


TE114 = 2.434 GHz
TM114 = 2.479 GHz

CONCLUSION: TE114 is excited with strong participation of TM114  We see the strength of Meep: while all the other analysis (including COMSOL FEA by NASA) have been eigenvalue analyses, the Meep solution is a transient solution in time, hence it automatically incorporates a spectrum analysis: it looks at participation of nearby modes.  (This can also be done with COMSOL FEA and other FEA programs of course, but nobody else has reported transient solutions up to now).

Having two modes with equal m, n, p, nearby results in participation of both modes (having TX114 mode shape, where X=either E or M).

It is interesting that although TE013 has a frequency of 2.45GHz, it was not excited (I am suspecting that the dipole antenna has trouble exciting TE01 mode shapes )

This analysis would be much easier and straightforward if when Meep results are shown, they are shown with NUMERICAL values as well, to ascertain the magnitude of what one is looking at
« Last Edit: 06/29/2015 08:24 PM by Rodal »

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