Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1878954 times)

Offline Rodal

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The stress at the small base is practically zero for all the previously shown time steps.  In order to save bandwidth I only show the last step

Therefore (?), all of the energy is attenuated by the side walls before it reaches the small base?

Todd

Dr. Rodal,
I suggest that I move the small base cuts one row toward the center to confirm that the cut I made was not actually inside the surface of the copper base. If you get markedly different results one row further inward, doesn't that mean that the current cut was most likely in the wrong place? And if you get very similar results, does that confirm the cut location? Or do I need to move the cut further inward to confirm? And even if the current cut is in the correct location, wouldn't a few cuts in toward the center tell us something? How many and how much?

Thanks for your offer to further clarify this.

I looked at the matrix, and established that the inner electromagnetic fields outermost positions in the longitudinal x direction are at:


Row 16 (rows ranging from 1 to 229) which should be the "Big Base" location

Row 215 (rows ranging from 1 to 229) which should be the "Small Base" location

Please confirm whether the present locations you supplied of the Big Base and the Small Base are at these locations (notice that the first row is defined as 1, not 0) or at another location (and if so at what location).

Thanks

______________

EDIT:

From your message:

@SeeShell -
Your .png and .csv files data is/are up have been uploaded here:

https://drive.google.com/folderview?id=0B1XizxEfB23tfm04QWNVVVVvT3gtcVAzRUp6T1BCLVpoV0EyeVVKR2ZxQkp2a3NKcUNPMU0&usp=sharing

I uploaded my meep data request file/form to hopefully explain what the data is, although it needs more English and fewer Scheme statements. The inside big end is at row 15 and small end at row 216 of the csv files, and the total run meep time t = 13.054 (6527 timesteps).

you don't specify whether you are counting rows starting at 0 or at 1 (1 is the most common convention), but it is apparent that the location of the big base and small base cuts appear to be 1 row beyond the correct location for the field next to the boundary, which should be 16 and 215 instead of 15 and 216
« Last Edit: 07/24/2015 02:13 PM by Rodal »

Offline Rodal

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The stress at the small base is practically zero for all the previously shown time steps.  In order to save bandwidth I only show the last step
Dr. Rodal,
Are you planning to do a slice through the center?
------
We continue by showing the stress tensor component sigma xx at the circular cross-sectional yz plane at  x=97, located on the interior, between the big end and the middle of the frustum.
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1403635#msg1403635
------

There is no center location csv file (at least labeled as such) among the csv files that were supplied by aero.  The csv files that were labeled were the Big Base and the Small Base that I already processed. 

aero is also to confirm as to whether what was labeled as the Small Base is at the correct location:
Row 215 (rows ranging from 1 to 229)

I attach a 3D view of the (azimuthal) Hyy Magnetizing field normal to the xz plane at time slice 00 showing that there is a non-zero magnetizing field throughout.  It is confirmed that the mode shape is indeed TM113.

Closest to you is the big base and furthest away is the small base, in this view of the planar cut (where the truncated cone is a trapezium in the planar cut).

Units are Meep units.
« Last Edit: 07/24/2015 02:27 PM by Rodal »

Offline SeeShells

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The stress at the small base is practically zero for all the previously shown time steps.  In order to save bandwidth I only show the last step
Dr. Rodal,
Are you planning to do a slice through the center?
------
We continue by showing the stress tensor component sigma xx at the circular cross-sectional yz plane at  x=97, located on the interior, between the big end and the middle of the frustum.
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1403635#msg1403635
------

There is no center location csv file (at least labeled as such) among the csv files that were supplied by aero.  The csv files that were labeled were the Big Base and the Small Base that I already processed. 

aero is also to confirm as to whether what was labeled as the Small Base is at the correct location:
Row 215 (rows ranging from 1 to 229)

I attach a 3D view of the (azimuthal) Hyy Magnetizing field normal to the xz plane at time slice 00 showing that there is a non-zero magnetizing field throughout.  It is confirmed that the mode shape is indeed TM113
Looking at the images he posted it does seem that the end of the antenna is too close to the large end plate but it is hard to see in the pictures.

Offline mrseanpaul81

I am a novice and my expertise has almost no relevance to this. i have been following this discussion since December 2014.

Has anyone attempted to use Eureqa (http://www.nutonian.com/products/eureqa/) to get an equation based on the available data from all the experiments.

Basically, Eureqa is an AI able to analyze data and come up with equations that fit the data (it independently discovered the Law Of Conservation of energy). Here is the wikipedia page (https://en.wikipedia.org/wiki/Eureqa).

Just the first time that I feel I could very slightly add something that could be constructive to this high level discussion :)

Offline Rodal

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Looking at the images he posted it does seem that the end of the antenna is too close to the large end plate but it is hard to see in the pictures.

Shell,

aero had posted that the antenna was only 1.5 mm (0.059 in) away from the big base in the message posted below. (*)

...It was also the same 58 mm antenna centered quarter wavelength from the inside face of the big base but rotated 90 degrees to an axial orentation. Note that 1/4 wave length is only slightly more than half of 58 mm, so the end of the antenna near the big base was about 1.5 mm away from the base, and excited with ez component although hy would have been more natural.

Q? Yea, Q was ridiculously high, like 60 million and the resonant frequency was like 2.463 GHz, which I ignored and made the run at 2.45 GHz.

(*) it may be even closer, given the fact that aero thought that the bases were one row beyond their actual locations: row  16  instead of row 15
« Last Edit: 07/24/2015 02:37 PM by Rodal »

Offline rfmwguy

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NSF-1701 quick update - ordered additional copper clad PCBs for top and bottom plates. Have thought a lot about the static test which I was going to do this weekend. After watching idiots on youtube, I will enclose the open 4 sides of the unit with my remaining copper mesh to further eliminate radiation leakage. (basically enclosing it in a faraday cage.

The top and bottom ends will be the solid copper clad PCB. It can be reconfigurable with mesh at the ends, but I plan on extended duration power-on, so safety is job #1.

Will video static test in a few days.

Offline Rodal

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After watching what on youtube ?

Offline WarpTech

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So... getting back to thrust-to-power ratios. What do you think of this result (attached) for an open-ended, tapered waveguide? Given my parameterization in the first equation is correct for small angles that is...
Todd
At first look I can't find the obvious error, but F/P has to equal 1/c, so it cannot be right.

If there is no waveguide, where the cut-off is 0-Hz, then it is 1/c. If there is a waveguide with a cut-off, the phase velocity is used and where there is a tapered waveguide the term in the denominator is used. So it gives what is expected in all 3 cases.
Todd

Offline ElizabethGreene

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Taking the numbers for making this flying saucer to fly (last part before conclusion) 1.9*10^22 A/s, so first second of hovering needs about 10^22 A, and only increasing quadratically. Any copper coil would sublimate instantly, going superconducting niobium-tin @ 200000 A/cm would require a coil with an astonishing section of 5 trillion square meters, more than surface of India...

I apologize if I misunderstand, but there are two dots above the I in that equation.  I believe that to mean that the rate of the change in the change of current flow needs to be ~ 10^22 amperes per second squared, not that the total power requirements are of that order of magnitude.  The latter part of the same paragraph implies that is roughly 5 amps at 10GHz.

Is that right?

Is that incorrect?

Offline SeeShells

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Looking at the images he posted it does seem that the end of the antenna is too close to the large end plate but it is hard to see in the pictures.

Shell,

aero had specified that the antenna was only 1.5 mm away from the big base in the message posted below.

...It was also the same 58 mm antenna centered quarter wavelength from the inside face of the big base but rotated 90 degrees to an axial orentation. Note that 1/4 wave length is only slightly more than half of 58 mm, so the end of the antenna near the big base was about 1.5 mm away from the base, and excited with ez component although hy would have been more natural.

Q? Yea, Q was ridiculously high, like 60 million and the resonant frequency was like 2.463 GHz, which I ignored and made the run at 2.45 GHz.
Looking at the configuration data it does say it was but it looks closer than .59 inch comparing to some of the other images in other tests. Maybe that's just an artifact of meep?

Everything about this test was a little off with the Q being so high, it looked like the antenna was acting to just tune the cavity to the million+ Q range. I don't know enough about how meep calculates Q before a run to even be sure.

Offline SeeShells

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NSF-1701 quick update - ordered additional copper clad PCBs for top and bottom plates. Have thought a lot about the static test which I was going to do this weekend. After watching idiots on youtube, I will enclose the open 4 sides of the unit with my remaining copper mesh to further eliminate radiation leakage. (basically enclosing it in a faraday cage.

The top and bottom ends will be the solid copper clad PCB. It can be reconfigurable with mesh at the ends, but I plan on extended duration power-on, so safety is job #1.

Will video static test in a few days.
Looking forward to seeing your setup!
Shell 

Offline Rodal

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Looking at the configuration data it does say it was but it looks closer than .59 inch comparing to some of the other images in other tests. Maybe that's just an artifact of meep?

Not an artifact apparently, aero thought that the bases were one row outside their actual locations: the big base is at row  16  instead of row 15.

QUESTION: how close did you want the antenna to be to the big base ?


Offline Rodal

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Everything about this test was a little off with the Q being so high, it looked like the antenna was acting to just tune the cavity to the million+ Q range. I don't know enough about how meep calculates Q before a run to even be sure.

We have to correct a misunderstanding: my understanding from the above message (and from a prior message were you though that aero had previously calculated a "Q=87,000+" for another run of Yang/Shell) is that you think that aero was calculating more reasonable Q's than this run before.

From this message of aero:

@Rodal - I'm not sure where you are getting  the data indicating that Q varies by 3 orders of magnitude, perhaps a miscommunication somewhere. If your source is meep Harminv data, then the correct values as I recorded them at the time of the runs are:

 Q   87,830,861
 Q   87,830,729
 Q   5,068,251
 Q   59,477,392

where the first two were using, I believe, a shorter dipole antenna (29 mm) and driving with the previously determined resonance frequency to hone in on the actual cavity resonance frequency as model. It is very consistently 2.46316012E+009 Hz within kHz. The final two were from the model with drive frequency = 2.45 GHz and antenna length = 58 mm as used to generate the 2 Yang-Shell data sets uploaded to Google drive.

It appears that ALL the Q's calculated by Meep so far are way too high for ALL the Meep runs he conducted.  Notice: 87 million rather than 87 thousand.

I calculate with my program Q=45,000 or so for Yang/Shell, for copper, and Q=15,000 for bronze, which are more reasonable numbers.

I think that there is an issue of a constant in Meep being way off its correct value (by orders of magnitude) or there is an issue of Meep units.    The Drude model parameters input into Meep apparently may be the culprit: giving an effective resistivity that is way too low.

I would suggest using Drude values that give a reasonable Q (I calculate 45,000 using copper for Yang/Shell) instead of the present values input for the Drude model for Meep.  Also look at whether there is a Meep units issue in going from the Drude model values suggested by deltaMass to the Drude model units used by Meep
« Last Edit: 07/24/2015 03:11 PM by Rodal »

Offline SeeShells

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Looking at the configuration data it does say it was but it looks closer than .59 inch comparing to some of the other images in other tests. Maybe that's just an artifact of meep?

Not an artifact apparently, aero thought that the bases were one row outside their actual locations: the big base is at row  16  instead of row 15.

QUESTION: how close did you want the antenna to be to the big base ?
A mirror of the one we ran on the small end plate perpendicular antenna.

Let's hold off for now as I'm trying to find this publication.
http://www.ncbi.nlm.nih.gov/pubmed/25321046
Single dipole evanescently coupled to a multimode waveguide

Found a full pub
https://www.osapublishing.org/view_article.cfm?gotourl=https%3A%2F%2Fwww%2Eosapublishing%2Eorg%2FDirectPDFAccess%2F8574813D-CAD2-B455-D0A507BFC5A64934_298621%2Foe-22-16-19633%2Epdf%3Fda%3D1%26id%3D298621%26seq%3D0%26mobile%3Dno&org=

If we want to do a 1/4 wave snub embedded the center of the large endplate it still will not (if I have this right) excite a TE mode but should give us more than a full dipole where areo put it and I told him pop it 1/4 wave from the end. The snub may be worth a run in the center to see if we can maintain the asymmetrical stress we just saw and still produce a relatively high Q and TM mode. 

Coming in from the side wall with the snub form what I understand will excite a Te mode if I'm getting this right.

Please bear with me as I'm still trying to learn about old white haired wizard's with hammers making waveguides. Honestly I thought when someone told me that they fine tuned particle accelerators copper walled cavities with ball peen hammers I thought they were pulling my leg. I guess not.
http://www.microwaves101.com/encyclopedias/waveguide-primer

Edit added more
« Last Edit: 07/24/2015 03:18 PM by SeeShells »

Offline X_RaY

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NSF-1701 quick update - ordered additional copper clad PCBs for top and bottom plates. Have thought a lot about the static test which I was going to do this weekend. After watching idiots on youtube, I will enclose the open 4 sides of the unit with my remaining copper mesh to further eliminate radiation leakage. (basically enclosing it in a faraday cage.

The top and bottom ends will be the solid copper clad PCB. It can be reconfigurable with mesh at the ends, but I plan on extended duration power-on, so safety is job #1.

Will video static test in a few days.

Good idea so far. In addition to that it may be helpful to use a bit of absorber material between the outside of your mesh cavity and the shield to suppress possible resonances in that volume.
« Last Edit: 07/24/2015 03:20 PM by X_RaY »

Offline rfmwguy

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After watching what on youtube ?
Don't want to provide links, but some numbskulls speaking russian made several videos of open magnetron horns lighting up bulbs, blowing up radios, etc. All done with kitchen magnetrons and an open horn or can. One of them had a leakage meter and it went off at least 30ft away from the open horn.

I'm sure the perps have a few less brain cells as a result  >:(

Offline WarpTech

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I would suggest using Drude values that give a reasonable Q (I calculate 45,000 using copper for Yang/Shell) instead of the present values input for the Drude model for Meep.  Also look at whether there is a Meep units issue in going from the Drude model values suggested by deltaMass to the Drude model units used by Meep

If that's the case, why not just compare your exact solution to @aero's Meep value, define a scaling factor and be done with it? Compare it at one or 2 different results and see if that gives reasonable numbers.
Todd

Offline Rodal

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I would suggest using Drude values that give a reasonable Q (I calculate 45,000 using copper for Yang/Shell) instead of the present values input for the Drude model for Meep.  Also look at whether there is a Meep units issue in going from the Drude model values suggested by deltaMass to the Drude model units used by Meep

If that's the case, why not just compare your exact solution to @aero's Meep value, define a scaling factor and be done with it? Compare it at one or 2 different results and see if that gives reasonable numbers.
Todd

That's why I bothered to give all these numerical data in my previous message (for Yang/Shell and for rfmwguy/NSF1701):

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1408596#msg1408596

Part of the Socratic method  (https://en.wikipedia.org/wiki/Socratic_method).  Are you saying that I'm not direct enough? :)
« Last Edit: 07/24/2015 03:19 PM by Rodal »

Offline sghill

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After watching what on youtube ?
Don't want to provide links, but some numbskulls speaking russian made several videos of open magnetron horns lighting up bulbs, blowing up radios, etc. All done with kitchen magnetrons and an open horn or can. One of them had a leakage meter and it went off at least 30ft away from the open horn.

I'm sure the perps have a few less brain cells as a result  >:(

I wonder if they go blind from the bathtub vodka or the magnetron radiation first...
Bring the thunder Elon!

Offline SeeShells

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