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#2840
by
Peter Lauwer
on 18 Dec, 2017 01:46
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Hi all,
I wanted to publish my collected EM Drive report that I finished back in Dec 2015 on arXiv but realized I need an endorsement from someone who already has publications. Is anyone willing to endorse me?
Attached is the collected report, nothing has been updated since I finished it. Hopefully someone can find something useful in there!
Thanks,
Kurt
Ability to endorse expires in 6 months. So I can not endorse you. But you can do as follows: browse current papers of your target field (I used pop-ph), find somebody who has the endorsement ability, directly send an endorsement request to him/her. Follow that request with an email with your paper attached. Often that person will just endorse you. If you do not hear back from him in 1 or 2 days, ask somebody else. Good luck!
Looks like a very thorough piece of work, Kurt.
But if the ability to endors expires in 6 months, this one expired a few days ago:
https://arxiv.org/abs/1706.04999I will check Tuesday, I will probably be fully occupied in the coming day.
Ch.. Peter
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#2841
by
WarpTech
on 20 Dec, 2017 22:25
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#2842
by
Mulletron
on 20 Dec, 2017 23:37
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#2843
by
LowerAtmosphere
on 21 Dec, 2017 03:38
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I'm waiting for more research in the metamaterials field to mature. While progress is being made most of it focuses on single layered materials which are a weak analogy to the EM Drive. Funding and time constraints drive the world but we watch keenly from the shadows regardless.
Chins up,
L.A.
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#2844
by
moreno7798
on 22 Dec, 2017 00:25
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Is that a modified version of EM Drive?
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#2845
by
covfefe
on 22 Dec, 2017 11:04
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From what I understand, EMdrive requires a high-Q cavity. But then I read about designs using dielectrics. Don't dielectrics suffer from a loss, increasing with frequency, which would cause the Q to be low? Also, I see designs using Magnetrons. Aren't these very unstable and noisy, RF-wise? Also, Magnetrons have a low life-span as compared to transistors, with a lifespan of 2,000 hours or so, and this can be drastically shortened by abuse which reflects energy back into the Magnetron, such as a poorly tuned cavity. So they seem like a potential source of trouble. I think that using transistors is a better idea. These design issues are what I saw on Zeller and Kraft's paper which was recently posted here.
Elsewhere, I am not sure if it was on this forum or not, I saw the suggestion of using graphene as the RF surface (coated on top of a structural material) because it is an excellent conductor. But doesn't it absorb microwaves?
Regards
C. O'Vfefe
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#2846
by
VAXHeadroom
on 22 Dec, 2017 15:06
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I'm not sure the chirp characteristics of the emitter on this cavity are conducive to MACH effect thrust generation...
Wishing everyone a very Merry Christmas!
Is that a modified version of EM Drive?
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#2847
by
Peter Lauwer
on 22 Dec, 2017 20:37
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From what I understand, EMdrive requires a high-Q cavity. But then I read about designs using dielectrics. Don't dielectrics suffer from a loss, increasing with frequency, which would cause the Q to be low? Also, I see designs using Magnetrons. Aren't these very unstable and noisy, RF-wise? Also, Magnetrons have a low life-span as compared to transistors, with a lifespan of 2,000 hours or so, and this can be drastically shortened by abuse which reflects energy back into the Magnetron, such as a poorly tuned cavity. So they seem like a potential source of trouble. I think that using transistors is a better idea. These design issues are what I saw on Zeller and Kraft's paper which was recently posted here.
Elsewhere, I am not sure if it was on this forum or not, I saw the suggestion of using graphene as the RF surface (coated on top of a structural material) because it is an excellent conductor. But doesn't it absorb microwaves?
Regards
C. O'Vfefe
I think I can safely answer "yes" to most of your questions and propositions.
Peter
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#2848
by
R.W. Keyes
on 24 Dec, 2017 15:45
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From what I understand, EMdrive requires a high-Q cavity. But then I read about designs using dielectrics. Don't dielectrics suffer from a loss, increasing with frequency, which would cause the Q to be low? Also, I see designs using Magnetrons. Aren't these very unstable and noisy, RF-wise? Also, Magnetrons have a low life-span as compared to transistors, with a lifespan of 2,000 hours or so, and this can be drastically shortened by abuse which reflects energy back into the Magnetron, such as a poorly tuned cavity. So they seem like a potential source of trouble. I think that using transistors is a better idea. These design issues are what I saw on Zeller and Kraft's paper which was recently posted here.
Elsewhere, I am not sure if it was on this forum or not, I saw the suggestion of using graphene as the RF surface (coated on top of a structural material) because it is an excellent conductor. But doesn't it absorb microwaves?
Regards
C. O'Vfefe
I think I can safely answer "yes" to most of your questions and propositions.
Peter
I used to have some hope for magnetrons, because they are a cheap way of generating high power. I didn't know about the small service life, though I did know they could be damaged. I've seen microwave ovens with very nice spectrums, and some with horrible spectrums. There are ways to reactively clean-up the signal by varying voltage, but I've since abandoned the magnetron in favor of the amplified output of a SDR (software defined radio) used as a signal source, which is the amplified. Since the SDR can also be used to test the resonant frequency of the cavity, I figure than I can switch between measuring resonance and transmitting the power signal, adjusting for any resonance change due to heat deformation.
Do ALL dielectrics show loss at 'useful' frequencies? Maybe there is some unknown dielectric that doesn't exhibit these principles.
IMHO, any copper frustum is useful just to model resonance, because the resistance is just too high, and this will cause heating. The cavity really needs to be superconducting. The problem is the difficulty working with superconductors. A 'metallic' superconductor, easy to machine, is MgB2. While for such 'traditional' superconductors it has a high critical temperature of 39K, this is still too low to be easily achievable. Meanwhile, 'high temperature' superconductors, which can be adequately cooled with liquid nitrogen (YBCO and BSCCO) are ceramics and difficult to form into a frustum. My thoughts now are that my own knowledge of how to fabricate cuprate semiconductors is limited, so I'd be better off working with MgB2 and dealing with the trouble and expense of deep-cryonics, while keeping an eye on progress in high-temperature superconductor fabrication because that's what the practical exploitation of the EMdrive effect will use. But my work is stalled by economic considerations at this time.
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#2849
by
mikegem
on 26 Dec, 2017 00:14
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Magnetrons routinely have longer MTBFs than 2,000 hours. I've had 2.45GHz maggies last >10K hours at full (2kW) power into well-behaved loads. 915MHz maggies have run at 50kW 15K hours for me, again in well-matched systems.
If you're willing to derate power by 50% or so, you can readily get 8K hours out of most oven microwave magnetrons, even in loads that aren't so well matched. Think running the nominal 1kW tube at 500W. There are air-cooled 2.45 GHz tubes that run at 2kW nominal, and could run for several K hours at 800 - 1000W.
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#2850
by
R.W. Keyes
on 26 Dec, 2017 04:05
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Magnetrons routinely have longer MTBFs than 2,000 hours. I've had 2.45GHz maggies last >10K hours at full (2kW) power into well-behaved loads. 915MHz maggies have run at 50kW 15K hours for me, again in well-matched systems.
If you're willing to derate power by 50% or so, you can readily get 8K hours out of most oven microwave magnetrons, even in loads that aren't so well matched. Think running the nominal 1kW tube at 500W. There are air-cooled 2.45 GHz tubes that run at 2kW nominal, and could run for several K hours at 800 - 1000W.
Perhaps there's a difference in quality between the magnetrons used in cheap microwave ovens, and those used, for instance, in radar. If the load in a microwave oven is the food, in certainly changes, and this might account for the quoted short service life. The only reference I can find to the 2,000 hr lifetime is from a company that is selling transistors to replace magnetrons for heating, so they may have just picked the best sounding number for their advertisements. COVFEFE, what is your source for the 2,000 hr service life?
Derating, yes, that makes sense. Does running a magnetron at a lower than spec'd power improve its signal purity?
When using a superconducting cavity, there is the danger of imperfect resonance and other factors creating heat which, if not removed quickly, can 'quench' the superconductor, leading it to be non-conductive with a high EM load to dump, and KABLOOM! Cavity wrecked, and magnetron either outright destroyed or its service life lessened. So, it makes sense to chill as far as is practical beyond the critical temperature, and quickly pump up cooling while cutting input power, and taking it offline for diagnostics. For this reason, a low-temperature superconductor such as niobium creates a real problem because there's not many degrees kelvin between ground state and it's superconductive state. MgB2 is better in this regard, but it's still not as good as the HTS (cuprates, etc).
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#2851
by
Peter Lauwer
on 27 Dec, 2017 14:53
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Btw, this must have been the quietest weeks of the EmDrive threads since they were established.
The coming year must be the year of truth, I think. Several government labs are involved now. Martin Tajmar of the TU Dresden for instance will probably have results to report. The Naval Research lab is probably already doing experiments. A couple of home builders, like Monomorphic and myself, will have results next year.
So, if the situation (the answer to whether the EmDrive generates an anomalous force or not) is still as vague as it is now next Christmas, we should be asking ourselves some critical questions.
All the best, Peter
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#2852
by
Eusa
on 27 Dec, 2017 17:03
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I already have my conclusions: artefacts all the way.
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#2853
by
Peter Lauwer
on 27 Dec, 2017 21:09
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I already have my conclusions: artefacts all the way.
And this forum is still interesting for you to follow?
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#2854
by
R.W. Keyes
on 27 Dec, 2017 22:33
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I already have my conclusions: artefacts all the way.
It's great that you have come to a decision of great personal importance. Now, you have to go back and tailor the facts, conjectures, experimental output, and experimental design to agree with your viewpoints. I've heard it's lots more fun than science is!
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#2855
by
Monomorphic
on 27 Dec, 2017 22:40
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#2856
by
RotoSequence
on 27 Dec, 2017 23:10
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I already have my conclusions: artefacts all the way.
It's great that you have come to a decision of great personal importance. Now, you have to go back and tailor the facts, conjectures, experimental output, and experimental design to agree with your viewpoints. I've heard it's lots more fun than science is!
There's really no need to be defensive about it; EM Drive will stand on its own merits, or it will fall on its own merits.
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#2857
by
Mulletron
on 27 Dec, 2017 23:37
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Something I've been pondering over is that it makes sense to me (I think) that a massive object can have an infinite change in acceleration yet still have a finite acceleration and a finite velocity. Does that make sense?
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#2858
by
Mulletron
on 27 Dec, 2017 23:50
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I'm not sure the chirp characteristics of the emitter on this cavity are conducive to MACH effect thrust generation...
Wishing everyone a very Merry Christmas!
Is that a modified version of EM Drive?
Interesting reading about how structural coloring and diffraction gratings work in nature. I don't think it applies to
grasshoppers crickets though, but it does to other periodic structures found in beetle wings and peacocks.
https://en.m.wikipedia.org/wiki/Structural_colorationhttps://en.m.wikipedia.org/wiki/Diffraction_grating
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#2859
by
masterharper1082
on 28 Dec, 2017 00:22
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Something I've been pondering over is that it makes sense to me (I think) that a massive object can have an infinite change in acceleration yet still have a finite acceleration and a finite velocity. Does that make sense?
Perhaps in the sense of the Dirac Delta Function (an impulse)?
https://en.wikipedia.org/wiki/Dirac_delta_function?wprov=sfla1mh
