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#1660
by
zellerium
on 26 Apr, 2016 20:00
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Hey Monomorphic,
That waveguide orientation is going to excite a TM mode in your wedge, correct? Do you have any reasoning behind this decision?
Also, have you considered using any sort of matched load similar to Yang?
High power ferrite circulators (what I believe Yang used) are probably not within any DIY budget, but with your FEKO experience I would bet you could devise a narrow band accepting aperture on the frustum side and a wideband matched load on the other side of the waveguide.
I wonder where the tradeoff of power into the cavity vs quality of resonance would be optimized for a magnetron.
I greatly admire all the work you've been doing! Thanks for posting
Thank you for the kind words!
I've been running sims on the waveguide today and noticed the TM mode excitation. Have already changed the orientation back to TE.
Didn't X_Ray also talk about a narrow band accepting aperture recently? He called it a periodic bandpassfilter.
Ah yes, that definitely looks like an elegant solution. I guess the trick would be sizing everything so that the intermediate cavities can dissipate enough heat to withstand deformation to maintain their resonant properties. I'd be afraid of the first cavity rejecting too much back to the magnetron. Maybe some absorbtive load inside could mitigate that effect?
It may be a better solution to integrate metallic tuning rods into the first cavity to get impedance match. This of course costs a bit of microwave power, also the additive filter cavities due to eddy currents at the inner surfaces, but it narrows the local bandwidth in the EMDrive main cavity.
The biggest issue would be the measurement of VSWR or even S-parameter in this configuration including the magnetron.
Against the thermal problems one could use materials with very small thermal expansion coefficient with a thin copper,silver or gold layer.
edit
Some kind of isolator circuit (circulator & load) should be work to protect the magnetron against overheating.
So we would design the system to operate somewhere above room temperature and account for a small thermal expansion.
If we start with 1000 W and lose 4dB, we would need to dissipate ~600 W. Ideally we would do this in a vacuum chamber through pure radiation so that the thrust measurement apparatus need not conduct any heat away and risk measurement errors.
I made a quick script assuming we're radiating to a surrounding at room temp and it definitely looks feasible. But that's still only 400 W into our frustum, what if we put 5 identical systems joined by waveguides to get closer to the kind of power Yang used?
edit: do we have a consensus on what amount of power was actually delivered into Yang's frustum? Last time I looked into it I didn't find an answer.
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#1661
by
Rodal
on 26 Apr, 2016 20:16
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Question to the HF gurus:
If spectral variation and sort of wandering bandwidths are a problem for reliable and stable mode shaping, then I wonder if there is a way to model and build a very narrow bandwidth 'pre-filter' wave guide that eats the poluted spectrum of an off-the-shelf magnetron and only then feeds the cleared narrow bandwidth spectrum with stable center frequency into an EM drive cavity?
BR
CW
One can only wonder about the direction of all this, as it was not too long ago that there was an article indicating that the Amplitude, Frequency and Phase modulation given by the Magnetron was a good thing to have:
http://nextbigfuture.com/2015/04/magnetron-powered-em-drive-construction.htmlThe first is that Shawyer and the Chinese both used magnetron RF sources for their experiments. An RF source that generates large AM, FM and PM modulation of the carrier wave with typical FM modulation bandwidth on the order of at least +/-20 MHz. (These time rate to change of energy modulations increase the Q-V density in our model.)
The second reason we found running these 3D Q-V plasma simulations for the EMPTY copper frustum, was that increasing the input power tends to focus the Q-V plasma flow from near omnidirectional from the frustum at low powers, to a much more jet like beam at higher powers measured in kW to tens of kW-rf. In fact the simulation for the 100W run predicted only ~50uN for our pure RF system with dielectric, while the 10kW run predicted a thrust level of ~6.0 Newton without a dielectric in the cavity. And at 100kW-rf it was now up to ~1300 Newton, but the input power to thrust production nonlinearity was starting to taper off around 50kW. Of course these Q-V plasma thrust predictions are based on the Q-V not being immutable and non-degradable, a feature we admit is not widely accepted by the mainstream physics community, at least at the moment.
Due to the above non-linear thrust scaling with input power predictions, we have started the build up of a 100W-to-1,200W waveguide magnetron RF power system that will drive one of our aluminum RF frustum cavities. Initially the test rig will follow Shawyer's first generation test rig that used a tetter-totter balance system in air only to see if we can generate similar thrust levels that Shawyer reported using a hermetic sealed box, which were in the ~16 to 300 milli-Newton range dependent on the Q-Factor of the frustum.
Now, precisely these things are seen as a bad thing that have to be filtered out ?
I also often see people writing that there is "no accepted theory for the EM Drive, therefore ..." and an acceptance that the EM Drive gets hotter due to induction heating, which leads to thermal expansion, which leads to detuning because the natural frequency changes with a change in dimensions due to thermal expansion. Yet the frequency modulation of the magnetron is now seen as a bad thing?
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#1662
by
X_RaY
on 26 Apr, 2016 20:26
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Hey Monomorphic,
That waveguide orientation is going to excite a TM mode in your wedge, correct? Do you have any reasoning behind this decision?
Also, have you considered using any sort of matched load similar to Yang?
High power ferrite circulators (what I believe Yang used) are probably not within any DIY budget, but with your FEKO experience I would bet you could devise a narrow band accepting aperture on the frustum side and a wideband matched load on the other side of the waveguide.
I wonder where the tradeoff of power into the cavity vs quality of resonance would be optimized for a magnetron.
I greatly admire all the work you've been doing! Thanks for posting
Thank you for the kind words!
I've been running sims on the waveguide today and noticed the TM mode excitation. Have already changed the orientation back to TE.
Didn't X_Ray also talk about a narrow band accepting aperture recently? He called it a periodic bandpassfilter.
Ah yes, that definitely looks like an elegant solution. I guess the trick would be sizing everything so that the intermediate cavities can dissipate enough heat to withstand deformation to maintain their resonant properties. I'd be afraid of the first cavity rejecting too much back to the magnetron. Maybe some absorbtive load inside could mitigate that effect?
It may be a better solution to integrate metallic tuning rods into the first cavity to get impedance match. This of course costs a bit of microwave power, also the additive filter cavities due to eddy currents at the inner surfaces, but it narrows the local bandwidth in the EMDrive main cavity.
The biggest issue would be the measurement of VSWR or even S-parameter in this configuration including the magnetron.
Against the thermal problems one could use materials with very small thermal expansion coefficient with a thin copper,silver or gold layer.
edit
Some kind of isolator circuit (circulator & load) should be work to protect the magnetron against overheating.
So we would design the system to operate somewhere above room temperature and account for a small thermal expansion.
If we start with 1000 W and lose 4dB, we would need to dissipate ~600 W. Ideally we would do this in a vacuum chamber through pure radiation so that the thrust measurement apparatus need not conduct any heat away and risk measurement errors.
I made a quick script assuming we're radiating to a surrounding at room temp and it definitely looks feasible. But that's still only 400 W into our frustum, what if we put 5 identical systems joined by waveguides to get closer to the kind of power Yang used?
edit: do we have a consensus on what amount of power was actually delivered into Yang's frustum? Last time I looked into it I didn't find an answer.
I think it could be a hard job to synchronize several sources. Maybe use a source with higher output?
http://tinyurl.com/jnqodb9or
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#1663
by
X_RaY
on 26 Apr, 2016 20:34
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Question to the HF gurus:
If spectral variation and sort of wandering bandwidths are a problem for reliable and stable mode shaping, then I wonder if there is a way to model and build a very narrow bandwidth 'pre-filter' wave guide that eats the poluted spectrum of an off-the-shelf magnetron and only then feeds the cleared narrow bandwidth spectrum with stable center frequency into an EM drive cavity?
BR
CW
One can only wonder about the direction of all this, as it was not too long ago that there was an article indicating that the Amplitude, Frequency and Phase modulation given by the Magnetron was a good thing to have:
http://nextbigfuture.com/2015/04/magnetron-powered-em-drive-construction.html
The first is that Shawyer and the Chinese both used magnetron RF sources for their experiments. An RF source that generates large AM, FM and PM modulation of the carrier wave with typical FM modulation bandwidth on the order of at least +/-20 MHz. (These time rate to change of energy modulations increase the Q-V density in our model.)
The second reason we found running these 3D Q-V plasma simulations for the EMPTY copper frustum, was that increasing the input power tends to focus the Q-V plasma flow from near omnidirectional from the frustum at low powers, to a much more jet like beam at higher powers measured in kW to tens of kW-rf. In fact the simulation for the 100W run predicted only ~50uN for our pure RF system with dielectric, while the 10kW run predicted a thrust level of ~6.0 Newton without a dielectric in the cavity. And at 100kW-rf it was now up to ~1300 Newton, but the input power to thrust production nonlinearity was starting to taper off around 50kW. Of course these Q-V plasma thrust predictions are based on the Q-V not being immutable and non-degradable, a feature we admit is not widely accepted by the mainstream physics community, at least at the moment.
Due to the above non-linear thrust scaling with input power predictions, we have started the build up of a 100W-to-1,200W waveguide magnetron RF power system that will drive one of our aluminum RF frustum cavities. Initially the test rig will follow Shawyer's first generation test rig that used a tetter-totter balance system in air only to see if we can generate similar thrust levels that Shawyer reported using a hermetic sealed box, which were in the ~16 to 300 milli-Newton range dependent on the Q-Factor of the frustum.
Now, precisely these things are seen as a bad thing that have to be filtered out ?
I also often see people writing that there is "no accepted theory for the EM Drive, therefore ..." and an acceptance that the EM Drive gets hotter due to induction heating, which leads to thermal expansion, which leads to detuning because the natural frequency changes with a change in dimensions due to thermal expansion. Yet the frequency modulation of the magnetron is now seen as a bad thing?
Good point!
Possible filtering should be limited to a necessary BW to be able to deliver an high ammount of RF energy into the frustum while thermal expansion in respect to your argument. Thanks for taking it into account! Hadn't thought on this.
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#1664
by
Tellmeagain
on 26 Apr, 2016 20:51
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...
A force, perpendicular to the longitudinal axis, has been measured and reported by several EM Drive experimenters, including at these Universities in Germany and in the USA:
* Prof. Tajmar et.al at TU Dresden
* Zeller, Kraft, Echols at California Polytechnic State Univ., San Luis Obispo, USA
I do notice that the force is a few orders of magnitude weaker than the usual radiation pressure, but it is in the perpendicular direction, and who knows whether it may be subject to magnification (as remarked by Rotosequence)
Are you absolutely positive that the perpendicular force you measured was due to Lorentz forces due to the cables? Was it reduced by moving the cables?
I believe the perpendicular force we observed was due to a lorentz force caused by the grounding wire which had not been intertwined with the postive and negative wires. I'm not sure of the connection to the paper you linked but unfortunately I don't have time to dive into it today.
I have successfully eliminated the horizontal deflection and have been observing slight vertical deflection (ie axial force) but only on certain occasions.
The sensitivity of our resonance is probably responsible for the inconsistent results: Our VNA is located in another building and we have been attempting to 'lock' the resonance and carry the cylinder over to the testing setup. When it is attached to the VNA it usually only takes a light tap to cause the resonance to shift or disappear completely.
Luckily a professor has purchased a portable VNA that I'll be using soon (this weekend perhaps) and I'll be able to lock a resonant position without moving the cavity and hopefully get some repeatable axial forces.
The deflections I have seen have been between 1~5 mN, just barely above the noise of our pendulum.
I also want to borrow a thermal camera to get a better idea of the heat distribution and the possible force caused by it.
Thank you Zellerium! I'd appreciate it if you give credit to my analysis as posted at,
http://forum.nasaspaceflight.com/index.php?topic=39004.msg1475977#msg1475977
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#1665
by
mikegem
on 26 Apr, 2016 20:51
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Question to the HF gurus:
If spectral variation and sort of wandering bandwidths are a problem for reliable and stable mode shaping, then I wonder if there is a way to model and build a very narrow bandwidth 'pre-filter' wave guide that eats the poluted spectrum of an off-the-shelf magnetron and only then feeds the cleared narrow bandwidth spectrum with stable center frequency into an EM drive cavity?
BR
CW
You can do waveguide pre-filtering, but I've found it more effective to clean up the magnetron power supply, which is the source of most variation in magnetron frequency and amplitude during normal operation.
Older microwave oven maggies run on half- or full-wave rectified but unfiltered high voltage developed from the 60Hz AC line with a transformer. This highly variable voltage modulates the magnetron output frequency and amplitude at either 60Hz or 120Hz (depending on half- or full wave rectifier).
Newer inverter-powered maggies sometimes have filtering that reduces ripple, but not much. Inverter supplies make the frequency and amplitude modulation happen at the inverter frequency or a multiple thereof.
I've built microwave sources for plasma deposition systems which needed good amplitude and frequency stability. I found that using a filtered, regulated HV magnetron supply was essential to get the stability I needed. At 2.45 GHz, my systems could tolerate short-term variations of about ±5MHz off freq, and about ±2% amplitude. I was able to meet those requirements without closing a power control loop around the magnetron. The DC power supply (from Spellman) had 0.1% regulation on output voltage and current. These can sometimes be found on Ebay, but are a no-no if you've no experience with high voltage applications.
One downside to waveguide pre-filtering might be that energy reflected from the pre filter will get back to the magnetron, further decreasing its stability. If you use a waveguide pre filter, you might consider putting a 3-port circulator with a dummy load between the magnetron and the pre filter. This will divert and absorb reflected energy, keeping it from getting back to the magnetron. A circ/dummy load is actually a good idea in any microwave power system if you need stability and you have something other than a perfectly resistive absorber as a load.
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#1666
by
Monomorphic
on 26 Apr, 2016 21:28
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I precisely modeled the extracted microwave waveguide "launcher" and attached it to the wedge geometry. Got strong TE013 at the predicted 2.44889Ghz! This model contains over 500 triangles and required ~10 minutes of processing.
EDIT: Just to be clear, I have been having problems all day with sims using custom designed waveguides. Second run using the extracted waveguide dimensions and voilą!
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#1667
by
zellerium
on 26 Apr, 2016 21:47
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...
A force, perpendicular to the longitudinal axis, has been measured and reported by several EM Drive experimenters, including at these Universities in Germany and in the USA:
* Prof. Tajmar et.al at TU Dresden
* Zeller, Kraft, Echols at California Polytechnic State Univ., San Luis Obispo, USA
I do notice that the force is a few orders of magnitude weaker than the usual radiation pressure, but it is in the perpendicular direction, and who knows whether it may be subject to magnification (as remarked by Rotosequence)
Are you absolutely positive that the perpendicular force you measured was due to Lorentz forces due to the cables? Was it reduced by moving the cables?
I believe the perpendicular force we observed was due to a lorentz force caused by the grounding wire which had not been intertwined with the postive and negative wires. I'm not sure of the connection to the paper you linked but unfortunately I don't have time to dive into it today.
I have successfully eliminated the horizontal deflection and have been observing slight vertical deflection (ie axial force) but only on certain occasions.
The sensitivity of our resonance is probably responsible for the inconsistent results: Our VNA is located in another building and we have been attempting to 'lock' the resonance and carry the cylinder over to the testing setup. When it is attached to the VNA it usually only takes a light tap to cause the resonance to shift or disappear completely.
Luckily a professor has purchased a portable VNA that I'll be using soon (this weekend perhaps) and I'll be able to lock a resonant position without moving the cavity and hopefully get some repeatable axial forces.
The deflections I have seen have been between 1~5 mN, just barely above the noise of our pendulum.
I also want to borrow a thermal camera to get a better idea of the heat distribution and the possible force caused by it.
Thank you Zellerium! I'd appreciate it if you give credit to my analysis as posted at, http://forum.nasaspaceflight.com/index.php?topic=39004.msg1475977#msg1475977
Absolutely, you deserve credit for that.
Thank you for your analysis!
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#1668
by
Tellmeagain
on 26 Apr, 2016 23:14
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#1669
by
SeeShells
on 26 Apr, 2016 23:21
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Question to the HF gurus:
If spectral variation and sort of wandering bandwidths are a problem for reliable and stable mode shaping, then I wonder if there is a way to model and build a very narrow bandwidth 'pre-filter' wave guide that eats the poluted spectrum of an off-the-shelf magnetron and only then feeds the cleared narrow bandwidth spectrum with stable center frequency into an EM drive cavity?
BR
CW
You can do waveguide pre-filtering, but I've found it more effective to clean up the magnetron power supply, which is the source of most variation in magnetron frequency and amplitude during normal operation.
Older microwave oven maggies run on half- or full-wave rectified but unfiltered high voltage developed from the 60Hz AC line with a transformer. This highly variable voltage modulates the magnetron output frequency and amplitude at either 60Hz or 120Hz (depending on half- or full wave rectifier).
Newer inverter-powered maggies sometimes have filtering that reduces ripple, but not much. Inverter supplies make the frequency and amplitude modulation happen at the inverter frequency or a multiple thereof.
I've built microwave sources for plasma deposition systems which needed good amplitude and frequency stability. I found that using a filtered, regulated HV magnetron supply was essential to get the stability I needed. At 2.45 GHz, my systems could tolerate short-term variations of about ±5MHz off freq, and about ±2% amplitude. I was able to meet those requirements without closing a power control loop around the magnetron. The DC power supply (from Spellman) had 0.1% regulation on output voltage and current. These can sometimes be found on Ebay, but are a no-no if you've no experience with high voltage applications.
One downside to waveguide pre-filtering might be that energy reflected from the pre filter will get back to the magnetron, further decreasing its stability. If you use a waveguide pre filter, you might consider putting a 3-port circulator with a dummy load between the magnetron and the pre filter. This will divert and absorb reflected energy, keeping it from getting back to the magnetron. A circ/dummy load is actually a good idea in any microwave power system if you need stability and you have something other than a perfectly resistive absorber as a load.
That's a huge ditto Mikegem!!! Like wise I designed and built semiconductor equipment and was exposed (not literally) to the magnetrons that are used in the industry. The keys are just like you said. Clean DC is critical. Also water cooling of the magnetron helps maintain the frequency drift from thermal heating. I've done both.
http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1985/04/page32/index.htmlWonderful to read your post, It's like from the horses mouth.
Shell
PS: back to testing and crunching numbers.
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#1670
by
rfmwguy
on 27 Apr, 2016 01:40
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Tooling to press lip on copper frustum. Frustum silver soldered into shape with torch. Brass rings to hold shape. Next is planing top and bottom edges flat. Seams to get filled with silver epoxy. Perspective distorted with cellphone cam. Small diameter looks bigger than it is.
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#1671
by
spupeng7
on 27 Apr, 2016 02:22
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Question to the HF gurus:
If spectral variation and sort of wandering bandwidths are a problem for reliable and stable mode shaping, then I wonder if there is a way to model and build a very narrow bandwidth 'pre-filter' wave guide that eats the poluted spectrum of an off-the-shelf magnetron and only then feeds the cleared narrow bandwidth spectrum with stable center frequency into an EM drive cavity?
BR
CW
That's exactly the idea behind the prefilter structure. The output of the filter will be several dB lower than the noisy magnetron source alone but with smaller BW.
It works. It is standard technique.
http://tinyurl.com/z7b4lam
http://www.2comu.com/showroom_waveguide_filter.html
http://www.smtconsultancies.co.uk/products/rtcc/rtcc.php
X-Ray,
could this idea be applied to an array of frustums? My 60 GHz experiment is suffering from a lack of volume in the waveguide. Could it somehow be possible to arrange a similar string of wedge shaped frustums so that they resonate together? JMN..
Edited to add quote below,
"Data! Data! Data! I can't make bricks without clay." Sherlock Holmes.
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#1672
by
CW
on 27 Apr, 2016 07:18
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@ Rodal
As an engineer, I ponder on things like stable signal spectra, integrity and systematic approaches.
As far as I understand it, the effective mode shapes in the cavity are dependent on the precise frequency content of the magnetron output at any point in time, which may vary. Please correct me, if I'm wrong. Based on this current understanding of mine, I can not see in how far a variable spectrum could possibly be interpreted as being advantageous in the effort to understand the exact conditions, under which the EM drive test articles may or may not produce unidirectional net acceleration. I could imagine, that the most problems in designing repeatable experiments in this field may lie in undefined spectral working points (ignoring the thermal expansion for the moment). What, if there is an actual EM drive effect, but the spectral magnetron variance produces ever-so slightly changing mode shapes that are causing the test article (akin to how an AC current only shifts electrons back and forth in a conductor) to be accelerated back and forth, resulting in no net acceleration? And then suddenly, for brief spans of time, accelerate the cavity towards the smaller frustum end, and at some times towards the other?
I think that there is a profund lack of controlled conditions in respect to signal spectrum integrity, which might produce random results. For some people, it may work - for some time. And for some, it never does. I think, that tightly controlling the HF spectrum is key to repeatable experiments. Otherwise, I think it's not an experiment, but throwing the dishes on the floor and expecting a fine orchestra piece to be playing out. Somewhere in that random spectrum, a nice tune may be hidden. Most of the times, it isn't.
Regarding the thermal expansion, I would rather design a finely controllable, clean HF source and electronically adapt that frequency to the thermal change of the cavity, instead of tediously trying to somehow mechanically adapt the cavity. Especially, if a slight tap on the adjustable end can already screw up the tuning. Let's be real here.. if this thing works and were put to use in space, it seems ridiculous to have to hire an EM drive shaman working obscure voodoo fine tuning magic, just for the damn thing to work. I think this thing should be as easy as applying power to a self-adjusting piece of hardware and just being good to go. Who would use a car, if the motor cylinders had to be manually fine-tuned each time we want the motor to run? I sure as hell wouldn't.
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#1673
by
X_RaY
on 27 Apr, 2016 08:30
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FYI
http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3732.htmlDirect measurements of the extraordinary optical momentum and transverse spin-dependent force using a nano-cantilever
M. Antognozzi, C. R. Bermingham, R. L. Harniman, S. Simpson, J. Senior, R. Hayward, H. Hoerber, M. R. Dennis, A. Y. Bekshaev, K. Y. Bliokh & F. Nori
AffiliationsContributionsCorresponding authors
Nature Physics (2016) doi:10.1038/nphys3732
Received 24 June 2015 Accepted 14 March 2016 Published online 25 April 2016
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Radiation pressure is associated with the momentum of light1, 2, and it plays a crucial role in a variety of physical systems3, 4, 5, 6. It is usually assumed that both the optical momentum and the radiation-pressure force are naturally aligned with the propagation direction of light, given by its wavevector. Here we report the direct observation of an extraordinary optical momentum and force directed perpendicular to the wavevector, and proportional to the optical spin (degree of circular polarization). Such an optical force was recently predicted for evanescent waves7 and other structured fields8. It can be associated with the ’spin-momentum’ part of the Poynting vector, introduced by Belinfante in field theory 75 years ago9, 10, 11. We measure this unusual transverse momentum using a femtonewton-resolution nano-cantilever immersed in an evanescent optical field above the total internal reflecting glass surface. Furthermore, the measured transverse force exhibits another polarization-dependent contribution determined by the imaginary part of the complex Poynting vector. By revealing new types of optical forces in structured fields, our findings revisit fundamental momentum properties of light and enrich optomechanics.
https://arxiv.org/ftp/arxiv/papers/1506/1506.04248.pdf
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#1674
by
OttO
on 27 Apr, 2016 11:15
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I am not sure if this has been shown:
http://arxiv.org/abs/1604.04301A 3D Printed Superconducting Aluminium Microwave CavityHere we show that a resonant microwave cavity 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable to the common 6061 alloy of aluminium.
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#1675
by
Notsosureofit
on 27 Apr, 2016 11:34
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Update: Data request for "Notsosureofit's Experiment"
(Relax, this is a numerical experiment, the nano "revolution" has the shop flat out so the rf components and the vacuum chamber just sit there for now while I try tp protect their turf.)
I'm looking to create a table of measured resonance data for frustum cavities with flat ends to compare with Einstein's (General Relativity) constant entropy calculations. While other cavity geometries are also suitable, the flat end frustum seems to be the most common.
The reported data should be:
Measured resonance frequency
Supposed mode in cylindrical notation (not required)
Frustum height
Frustum large diameter
Frustum small diameter
Air or vacuum dielectric
Thanks All,
@Notsosureofit
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#1676
by
OttO
on 27 Apr, 2016 11:37
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#1677
by
Rodal
on 27 Apr, 2016 12:27
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@ Rodal
As an engineer, I ponder on things like stable signal spectra, integrity and systematic approaches.
As far as I understand it, the effective mode shapes in the cavity are dependent on the precise frequency content of the magnetron output at any point in time, which may vary. Please correct me, if I'm wrong. Based on this current understanding of mine, I can not see in how far a variable spectrum could possibly be interpreted as being advantageous in the effort to understand the exact conditions, under which the EM drive test articles may or may not produce unidirectional net acceleration. I could imagine, that the most problems in designing repeatable experiments in this field may lie in undefined spectral working points (ignoring the thermal expansion for the moment). What, if there is an actual EM drive effect, but the spectral magnetron variance produces ever-so slightly changing mode shapes that are causing the test article (akin to how an AC current only shifts electrons back and forth in a conductor) to be accelerated back and forth, resulting in no net acceleration? And then suddenly, for brief spans of time, accelerate the cavity towards the smaller frustum end, and at some times towards the other?
I think that there is a profund lack of controlled conditions in respect to signal spectrum integrity, which might produce random results. For some people, it may work - for some time. And for some, it never does. I think, that tightly controlling the HF spectrum is key to repeatable experiments. Otherwise, I think it's not an experiment, but throwing the dishes on the floor and expecting a fine orchestra piece to be playing out. Somewhere in that random spectrum, a nice tune may be hidden. Most of the times, it isn't.
Regarding the thermal expansion, I would rather design a finely controllable, clean HF source and electronically adapt that frequency to the thermal change of the cavity, instead of tediously trying to somehow mechanically adapt the cavity. Especially, if a slight tap on the adjustable end can already screw up the tuning. Let's be real here.. if this thing works and were put to use in space, it seems ridiculous to have to hire an EM drive shaman working obscure voodoo fine tuning magic, just for the damn thing to work. I think this thing should be as easy as applying power to a self-adjusting piece of hardware and just being good to go. Who would use a car, if the motor cylinders had to be manually fine-tuned each time we want the motor to run? I sure as hell wouldn't.
1) First one should consider the experimental claims. The experimental claims that resulted in the highest force/PowerInput were the experiments that used magnetrons: particularly the experiments by Yang. Prof. Yang has by far, the highest force/InputPower claimed for any EM Drive experiment. It eclipses any non-superconducting claim: claiming over 300,000 times the force/InputPower of a perfectly collimated photon rocket. Prof. Yang claims these results with a magnetron that is not reported to be filtered or subject to the modifications being proposed to "clean" the output of the magnetron. Hence experimenters insisting on modifying the magnetron to have a "clean source" are apparently disregarding the experimental record. Do these experimenters think that Prof. Yang's results are experimental artifacts?
2) Concerning your statement
"I think, that tightly controlling the HF spectrum is key to repeatable experiments. Otherwise, I think it's not an experiment, but throwing the dishes on the floor and expecting a fine orchestra piece to be playing out. Somewhere in that random spectrum, a nice tune may be hidden. Most of the times, it isn't.
"
it presumes that the physical phenomenon is a deterministic process and that it is a linear process. Yes, I also think that those insisting in filtering the magnetron to reduce the bandwidth, reduce frequency modulation, amplitude modulation and phase modulation are presuming that the process is deterministic, and linear. Another hint that they think so is that they think that one can use a simple control loop to control the process. Yet, there is no evidence that the process is deterministic and linear. On the contrary.
Quantum mechanics does not specify the outcome of individual experiments but only the probabilities.
If the process would not be deterministic, but instead involve random variables (*), the presumption would be wrong: it actually may be better to have frequency and phase modulation. Several theories explaining the EM Drive are based on the Quantum Vacuum, and therefore the process could involve random variables instead of being deterministic. The plasma code of Dr. White is one of those theories, see my previous message which quoted Paul March in these regards.
The plasma code of Dr. White has predicted not just the amplitude of force response but also the direction of force response in a number of cases. (**)
If the process is very nonlinear, filtering the magnetron may be a wrongheaded approach. If the process is nonlinear and not deterministic, a control loop may not work.
Further testing will tell the story: what experiments will result in the maximum force/InputPower ? 
______________
(*) Randomness does not mean that the statistics need to be Gaussian.
(**)
Although Shawyer and McCulloch's equations model the process as being linear: the force being a linear function of power input and the quality of resonance Q, previous reports by Star-Drive indicate that the outcome of the plasma QV code is not linearly dependent on Q and not linearly dependent on power input.
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#1678
by
JaimeZX
on 27 Apr, 2016 13:42
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Dr. Rodal, I lack the expertise to non-concur with anything in your above statement. That said, it should also be impossible to argue with CW's assertion that filtering the RF source to provide consistent frustum input is one key to a repeatable experiment.
Presumably if I have a source from a Panasonic NE-1064 and rfmwguy has an LG LMHM2237ST and Shells is using a Frigidaire FGMV175QF at different ambient temperatures, pressures, AC line voltages, & etc., & etc. - whether or not the effect is due to QV interaction or Unruh radiation, or CU++ spalling, or _________ the experiments are not exactly repeatable (or less so) without knowing the details of the input frequency, bandwidth, power, and so on.
Are we wrong here?
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#1679
by
rfmwguy
on 27 Apr, 2016 13:55
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@CW
Filtering will reduce sidebands but will reflect stopband energy back to the magnetron. Some speculate that this can help stabilize the "free running oscillator" effect of the mag but I have my doubts. My guess is it would mainly be lost to heat. However, filtering does give a "cleaner" source for the cavity. Now whether that is a force producer remains to be seen.
My testing next month will use the same magnetron and injection from September, just a different test stand and cavity. This was on purpose to see what solid sidewalls, heavier endplates, polishing, smaller dimensions optimized for the magnetron and better overall construction have anything to do with the force improvement goal of 100.
I'm reasonably certain I may not achieve this with only these (mechanical) steps. From there, I was going to go solid state like Jamie might and use the NXP device. Think it will be important to stabilize the frequency. Whether AM, FM or Phase modulation is part of the secret or pulse duration or rep rate is, I am not certain. That's what experimentation is for.
