Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1798800 times)

Offline SeeShells

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Ok let me take it down to a simple analogy I can understand. Nice piece of work BTW.

I have a pressure tank for air and it looks like a Frustum cavity, big end little end. I fill it up with pressure then put a speaker in the end and blast away with the 1812 Overture towards one end that's high with the differential pressure from the speaker. The cannons stet off and pressure differential inside of the tank becomes more asymmetrical with more energy and pressure accumulated at one end. The tank sits, unmoving.

Give me a link to the outside, a hole and I can move it.

Added a little
« Last Edit: 07/18/2015 08:26 PM by SeeShells »

Offline Rodal

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The link to the outside (or to some outside field) is of paramount importance, otherwise it will not move (maybe just explode :)    )
« Last Edit: 07/18/2015 08:52 PM by Rodal »

Offline aero

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The link to the outside (or to some outside field) is of paramount importance, otherwise it will not move (maybe just explode :)    )

Hasn't that always been the fundamental problem needing a solution?
Retired, working interesting problems

Offline SeeShells

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The link to the outside (or to some outside field) is of paramount importance, otherwise it will not move (maybe just explode :)    )

I can hear it through the walls of the tank louder at one end and that's the key as I see it.

If we work backwards instead of inside out we hit the wall of the tank and there is where it falls apart.

Evanescent waves tunneling quantum superluminal effects that throw this thing for a loop and me.

I watched two videos this morning as a refresher.
In the first video a basic understanding of Maxwell's and even Newton's laws providing a basic understanding of waves then feeling good about myself I delved into to a head spinning review of the formation of evanescent waves, barrier tunneling and even a hint of superluminal effects.
I'll be the first to admit it was getting deep in the second video when I asked where in the hell did he get that 1 from?





Offline SeeShells

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The link to the outside (or to some outside field) is of paramount importance, otherwise it will not move (maybe just explode :)    )

Hasn't that always been the fundamental problem needing a solution?
Out west we have a saying... YEEUPP.

Offline aero

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
Retired, working interesting problems

Offline BL

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Ref TheTraveller Post #4570

I don't know your critical specs, so I don't know if these are 'better' or not:

Insulated Wire:   http://www.iw-microwave.com/cable_specs

The cable series numbers are their nominal diameter in mils.  To get specs for a specific cable just click on the cable number.  The 280 series provides around .25 dB/m @ 2.5 GHz and will handle around 1 kw, for example.

IW brags about their low insertion loss but the ones I have used tend to be relatively stiff for a given diameter.

Or

W. L. Gore:  http://tools.gore.com/gmcacalc/#/

The Gore link is to their cable calculator, which provides specs for connectorized cables of the length specified at the freq of interest.  ( .32 db/1 m @ 2.5 GHz, with a power rating of 1532 watts, for example.)

Gore is known for extreme flexibility, low insertion loss, good VSWR, and tolerance for small radius bends  They also define the term 'expensive cables'.

Offline Rodal

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
the result of eps averaging no doubt.  Codes like Meep that do eps averaging should have a routine to output the location of where Boundary Conditions are enforced.  If it doesn't, that's what we expect from a free open code,  where the user is expected to do it.  At the moment I'm using Mathematica to figure out where the nodes are. 

Offline SeeShells

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
I'm not stirring the pot here but asking if anyone you know or anyone here of has looked at this program running in Linux written in C?
http://www.met.reading.ac.uk/clouds/maxwell/

Offline SeeShells

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Ref TheTraveller Post #4570

I don't know your critical specs, so I don't know if these are 'better' or not:

Insulated Wire:   http://www.iw-microwave.com/cable_specs

The cable series numbers are their nominal diameter in mils.  To get specs for a specific cable just click on the cable number.  The 280 series provides around .25 dB/m @ 2.5 GHz and will handle around 1 kw, for example.

IW brags about their low insertion loss but the ones I have used tend to be relatively stiff for a given diameter.

Or

W. L. Gore:  http://tools.gore.com/gmcacalc/#/

The Gore link is to their cable calculator, which provides specs for connectorized cables of the length specified at the freq of interest.  ( .32 db/1 m @ 2.5 GHz, with a power rating of 1532 watts, for example.)

Gore is known for extreme flexibility, low insertion loss, good VSWR, and tolerance for small radius bends  They also define the term 'expensive cables'.
I have a quote coming from Gore, I suspect your right they are not cheap.

Offline Rodal

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
I'm not stirring the pot here but asking if anyone you know or anyone here of has looked at this program running in Linux written in C?
http://www.met.reading.ac.uk/clouds/maxwell/

Seems to only solve solutions to Maxwell's equations in a 2D domain (using the Finite-Difference Time-Domain method) not 3D.  As such it would model the truncated cone as a perfectly flat sheet with trapezium boundaries.  The azimuthal electromagnetic field vectors would become scalar dots in such a model. 
« Last Edit: 07/18/2015 10:06 PM by Rodal »

Offline LasJayhawk

Ref TheTraveller Post #4570

I don't know your critical specs, so I don't know if these are 'better' or not:

Insulated Wire:   http://www.iw-microwave.com/cable_specs

The cable series numbers are their nominal diameter in mils.  To get specs for a specific cable just click on the cable number.  The 280 series provides around .25 dB/m @ 2.5 GHz and will handle around 1 kw, for example.

IW brags about their low insertion loss but the ones I have used tend to be relatively stiff for a given diameter.

Or

W. L. Gore:  http://tools.gore.com/gmcacalc/#/

The Gore link is to their cable calculator, which provides specs for connectorized cables of the length specified at the freq of interest.  ( .32 db/1 m @ 2.5 GHz, with a power rating of 1532 watts, for example.)

Gore is known for extreme flexibility, low insertion loss, good VSWR, and tolerance for small radius bends  They also define the term 'expensive cables'.
I have a quote coming from Gore, I suspect your right they are not cheap.

A 4' Gore-Tex cable terminated in type N connectors ran about $400... In the mid 1990's.

You should be sitting down when you open the quote.

Offline SeeShells

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
I'm not stirring the pot here but asking if anyone you know or anyone here of has looked at this program running in Linux written in C?
http://www.met.reading.ac.uk/clouds/maxwell/

Seems to only solve solutions to Maxwell's equations in a 2D domain (using the Finite-Difference Time-Domain method) not 3D.  As such it would model the truncated cone as a perfectly flat sheet with trapezium boundaries.  The azimuthal electromagnetic field vectors would become scalar dots in such a model.
Ahh that makes sense I knew it was a 2D program using the FDTD method but didn't figure on the vectors we need becoming dots and unusable. Thanks Doc!

Offline SeeShells

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Ref TheTraveller Post #4570

I don't know your critical specs, so I don't know if these are 'better' or not:

Insulated Wire:   http://www.iw-microwave.com/cable_specs

The cable series numbers are their nominal diameter in mils.  To get specs for a specific cable just click on the cable number.  The 280 series provides around .25 dB/m @ 2.5 GHz and will handle around 1 kw, for example.

IW brags about their low insertion loss but the ones I have used tend to be relatively stiff for a given diameter.

Or

W. L. Gore:  http://tools.gore.com/gmcacalc/#/

The Gore link is to their cable calculator, which provides specs for connectorized cables of the length specified at the freq of interest.  ( .32 db/1 m @ 2.5 GHz, with a power rating of 1532 watts, for example.)

Gore is known for extreme flexibility, low insertion loss, good VSWR, and tolerance for small radius bends  They also define the term 'expensive cables'.
I have a quote coming from Gore, I suspect your right they are not cheap.

A 4' Gore-Tex cable terminated in type N connectors ran about $400... In the mid 1990's.

You should be sitting down when you open the quote.
More than even I thought. Thanks for the heads up.
Shell

Offline Rodal

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
I'm not stirring the pot here but asking if anyone you know or anyone here of has looked at this program running in Linux written in C?
http://www.met.reading.ac.uk/clouds/maxwell/

Seems to only solve solutions to Maxwell's equations in a 2D domain (using the Finite-Difference Time-Domain method) not 3D.  As such it would model the truncated cone as a perfectly flat sheet with trapezium boundaries.  The azimuthal electromagnetic field vectors would become scalar dots in such a model.
Ahh that makes sense I knew it was a 2D program using the FDTD method but didn't figure on the vectors we need becoming dots and unusable. Thanks Doc!
It would be an approximation to an EM Drive with a uniform cross-section-height throughout (not flared cs height) rectangular cross section, where the cross-sectional width is much longer than the cross-sectional height, so as to have an almost flat field configuration.
« Last Edit: 07/18/2015 10:35 PM by Rodal »

Offline Eer

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Hello,

I've been tinkering around with meep on Debian, and I have a procedure for installing meep 1.3 on Debian 8, which packages the older meep 1.2 by default:

# apt-get install h5utils openmpi-bin
# apt-get build-dep meep-openmpi
This installs everything we'll need for dependencies, but by default ./configure won't find libhdf5, so we need to do this.
# cd /usr/lib/x86_64-linux-gnu/
# ln -s libhdf5_openmpi.so libhdf5.so
# export CPPFLAGS="-I/usr/include/hdf5/openmpi"
Now we can head back to our source-building directory and get on with it.
# wget http://ab-initio.mit.edu/meep/meep-1.3.tar.gz
# cd meep-1.3
# ./configure --with-mpi --prefix=$HOME
Obviously this assumes $HOME is in your path, you can install it wherever.
# make
# make install


If anyone has meep files that they lack the time to process on their own hardware, I have a reasonably powerful system that can crank through a 12-thread run of NSF-1701.ctl in about 40 minutes, as well as a web server (nginx) running so I can package the output files (h5, csv, png, whatever) and provide a link.  I'm a sysadmin by trade, and the last physics I took was Newton, so I don't yet know enough to write my own Scheme scripts for meep and get any meaningful output.

Yes, for those wondering, I'm also tidux on /r/emdrive.

Attempting to follow this on Ubunto, which is, I think, Debian jessie (8.1).

I don't wind up with a libhdf5_openmpi.so, but rather x86_64-linux-gnu/libhdf5.so -> libhdf5.so.7.0.0

There's no directory /usr/include/hdf5/openmpi, but there is /usr/include/openmpi.  The hdf5* files are in /usr/include.

meep-1.3 requires libctl version 3.2 or later, but version 3.1 got installed.

These don't seem insurmountable, but it sounds like I am not driving against the same repository you are.  Can you give me a pointer as to how to update my repository list to match yours for, e.g., meep-openmpi ?

Thanks


Offline rq3

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Ref TheTraveller Post #4570

I don't know your critical specs, so I don't know if these are 'better' or not:

Insulated Wire:   http://www.iw-microwave.com/cable_specs

The cable series numbers are their nominal diameter in mils.  To get specs for a specific cable just click on the cable number.  The 280 series provides around .25 dB/m @ 2.5 GHz and will handle around 1 kw, for example.

IW brags about their low insertion loss but the ones I have used tend to be relatively stiff for a given diameter.

Or

W. L. Gore:  http://tools.gore.com/gmcacalc/#/

The Gore link is to their cable calculator, which provides specs for connectorized cables of the length specified at the freq of interest.  ( .32 db/1 m @ 2.5 GHz, with a power rating of 1532 watts, for example.)

Gore is known for extreme flexibility, low insertion loss, good VSWR, and tolerance for small radius bends  They also define the term 'expensive cables'.
I have a quote coming from Gore, I suspect your right they are not cheap.

Shell, you'll probably need another gofundme to buy Gore cables. You may be able to get samples, it never hurts to ask.

Semirigid coax is another way to go, unless you absolutely need flexibility. In either case, it is good assembly practice to "exercise" the cable over it's full temperature range (or more) before assembly to force it to stabilize, especially in phase sensitive applications. For those attempting a phase locked loop configuration for the frustum drive, this may be critical to success.

Not being insulting here (or at least trying not to), but all the uwave neophytes need to keep in mind that a 3 dB loss is 0.5 milliwatt in the cable with a 0 dBm signal. Its 500 Watts with a 60 dBm signal.

Ideally your magnetron or better yet, klystron, will be mounted directly, and hermetically, on the frustum. The only need for coax will be for low level signal "sniffing" through very lightly coupled antenna ports, or via a short dual directional coupler in waveguide between the magnetron/klystron and frustum.
« Last Edit: 07/18/2015 10:35 PM by rq3 »

Offline SeeShells

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Dr. Rodel,
Attached is a screen shot of a corner of the .h5 file for SeeShell's model. It illustrates the problem of accurately locating the inside corner of the big end of the frustum. No such problem at the small end.
I'm not stirring the pot here but asking if anyone you know or anyone here of has looked at this program running in Linux written in C?
http://www.met.reading.ac.uk/clouds/maxwell/

Seems to only solve solutions to Maxwell's equations in a 2D domain (using the Finite-Difference Time-Domain method) not 3D.  As such it would model the truncated cone as a perfectly flat sheet with trapezium boundaries.  The azimuthal electromagnetic field vectors would become scalar dots in such a model.
Ahh that makes sense I knew it was a 2D program using the FDTD method but didn't figure on the vectors we need becoming dots and unusable. Thanks Doc!
It would be an approximation to an EM Drive with a rectangular cross section, closer to a rectangular cross section where the cross-sectional width is much longer than the cross-sectional height, so as to have an almost flat field configuration.
And when in the case of perforated copper a 2D line just wouldn't cut it. I've picked the brain of one of the scientist at the SCSC (he's the one who took the pic of me standing in front of the RF injectors, that's RF power) and he seems to think that because of the angle and size that the losses should be minimal.

You know for years evanescent waves were though to be just ghosts with no way to do work through a barrier. Maxwell's equations stated that. Now that's all under question with some of the new studies that are showing extraordinary spin and momentum can be carried. This old gal learned something new.

Offline SeeShells

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Hello,

I've been tinkering around with meep on Debian, and I have a procedure for installing meep 1.3 on Debian 8, which packages the older meep 1.2 by default:

# apt-get install h5utils openmpi-bin
# apt-get build-dep meep-openmpi
This installs everything we'll need for dependencies, but by default ./configure won't find libhdf5, so we need to do this.
# cd /usr/lib/x86_64-linux-gnu/
# ln -s libhdf5_openmpi.so libhdf5.so
# export CPPFLAGS="-I/usr/include/hdf5/openmpi"
Now we can head back to our source-building directory and get on with it.
# wget http://ab-initio.mit.edu/meep/meep-1.3.tar.gz
# cd meep-1.3
# ./configure --with-mpi --prefix=$HOME
Obviously this assumes $HOME is in your path, you can install it wherever.
# make
# make install


If anyone has meep files that they lack the time to process on their own hardware, I have a reasonably powerful system that can crank through a 12-thread run of NSF-1701.ctl in about 40 minutes, as well as a web server (nginx) running so I can package the output files (h5, csv, png, whatever) and provide a link.  I'm a sysadmin by trade, and the last physics I took was Newton, so I don't yet know enough to write my own Scheme scripts for meep and get any meaningful output.

Yes, for those wondering, I'm also tidux on /r/emdrive.

Attempting to follow this on Ubunto, which is, I think, Debian jessie (8.1).

I don't wind up with a libhdf5_openmpi.so, but rather x86_64-linux-gnu/libhdf5.so -> libhdf5.so.7.0.0

There's no directory /usr/include/hdf5/openmpi, but there is /usr/include/openmpi.  The hdf5* files are in /usr/include.

meep-1.3 requires libctl version 3.2 or later, but version 3.1 got installed.

These don't seem insurmountable, but it sounds like I am not driving against the same repository you are.  Can you give me a pointer as to how to update my repository list to match yours for, e.g., meep-openmpi ?

Thanks
I hope all of you meeps out there know how seriously appreciated you are. I'd give you each a hug if I could. From the builders to the theorists we all gain from your work.

Shell

Offline Rodal

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We continue the program started with posts

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1403629#msg1403629
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404000#msg1404000
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404004#msg1404004
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404005#msg1404005
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404006#msg1404006
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404754#msg1404754
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1404783#msg1404783

showing the stress (force/unitArea) on the small and the big Base for what is believed to be Yang's EM Drive geometry:  (Db=0.201m,Ds=0.1492m,L=0.24m), with the dipole antenna previously used by aero for the RFMWGUY geometry, but this time located near the big end: dipole 0.058 m long in the y direction, with Ez excitation where Cartesian axes y and z are perpendicular to longitudinal axis x.
 

The stress tensor σxx (*) component is obtained using Wolfram Mathematica ( http://www.wolfram.com/mathematica/ ) , post-processed from the transient Finite Difference (using Meep) solution for RF feed ON.

The stress component σxx  has a negative magnitude, in both bases: it is compressive on both the Small and the Big bases.  Since it has negative magnitude on both bases it obviously points in different directions:  at the big base it points in the direction from the small base to the big base while at the small base it points in the direction from the big base to the small base.  From the interior to the surface in both cases.  In other words, the electromagnetic field exerts a pressure on both surfaces.

The stress is distributed in the shape of a bell at the big base (narrowly distributed over the central 1/3 of the diameter) and in the shape of a central bell with two crescent sections at the outer periphery at the small base.  This distribution is quite different from the distribution in the case of rfmwguy, which as one may recall had two crescent sections at the periphery for the big base, close to zero at the center, and a bell shape at the small base with no crescent periphery sections.

Notice that several changes  were made at once for this Meep FD model:

1) the geometry from rfmwguy's dimensions to Yang's dimensions.
2) the location of the antenna from being near the small base for rfmwguy to being near the big end for Yang's geometry.
3) the Finite Difference mesh is coarser for the smaller big diameter of the Yang model (0.201m) than the big diameter of rfmwguy's model (0.2794 m): a less precise FD mesh with less nodes in the cross-section.  The actual physical distance between nodes was kept practically the same.  But what matters for a numerical discretization of a partial differential equation is the number of nodes to characterize the fields in the solution to the partial differential equation.  For the same natural mode shape it would be best to keep the same mesh regardless of the actual physical size.

We observe the behavior that we saw for rfmwguy's geometry: the antenna overwhelms the natural TM11 mode that would occur otherwise:  there is no trace of the two crescent shapes this time at the big base because the antenna is near the big base.

It is also very interesting to point out that:

1) The maximum stress at the small base is much larger than the maximum stress at the big base

2) the time at which the maximum stress occurs at the big base is NOT phase-shifted with respect to the time at which the maximum stress occurs at the small base.  I believe that this is due to placing the antenna near the big base rather than the small base.  I think that this is bad.

3) I will post the net force vs. time in a future post.
______________________________






(*)  (we denote by σxx= T11 the contravariant component of the tensor acting along the longitudinal direction "x" of the EM Drive, normal to the the plane yz having normal x, where direction "1" is "x")

(**) For the copper diamagnetism is assumed such that the magnetization M is assumed proportional to the applied magnetic field such that for free space it is assumed that M is zero in free space in the relationship 

(***) The Stress calculations are for an Input Power of 43 Watts (similar to the value used by NASA in some of their runs).  The Stress values are proportional to the Input Power, so for example, if the Input Power were 860 Watts, that means that the calculated values for Stress are 860 Watts/ 43 Watts = 20 times greater than shown in the plots.    In other words, for 860 Watts InputPower, the values for Stress in the plots need to be multiplied by a factor of 20.
« Last Edit: 07/20/2015 08:09 PM by Rodal »

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