Quote from: Rodal on 06/29/2015 12:32 pmQuote from: aero on 06/29/2015 01:05 amQuote from: Rodal on 06/29/2015 12:01 am... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency, TM212 is 6.5% lower and TE213 is 9.2% lower. frequency. Using those estimates, Meep should have picked up TM114 (except I was exciting TE modes) and maybe TE114. Probably not TM212 or TE213. I guess we'll see in the fields, if someone can get some numbers somehow....1) For 10.2 inches you should place the antenna to excite an electric excitation, because the resonance is transverse electric mode shape TE013 at 2.45GHz with L=10.2 inches. When you state that TM114 would be excited instead of TE013, does that mean that you placed the antenna to excite a magnetic instead of electric mode ? .2) Some time ago you were able to calculate with Meep the net force on the EM Drive. It would be most interesting if you could calculate the net force on the EM Drive at every finite difference time step for the cases of rfmwguy being studied, so that we can plot the force vs. time, and see what its time behavior looks like.There are indications in your plots that the force may not be a sine curve with time, and therefore that the force may sum up to a net amount over an integer number of periods, but we need numerical confirmation (or denial) of this.When you say net force, you mean Maxwell stress tensor ? Like in this example (which I have tested and works): http://ab-initio.mit.edu/wiki/index.php/Meep_Tutorial/Optical_forces ?
Quote from: aero on 06/29/2015 01:05 amQuote from: Rodal on 06/29/2015 12:01 am... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency, TM212 is 6.5% lower and TE213 is 9.2% lower. frequency. Using those estimates, Meep should have picked up TM114 (except I was exciting TE modes) and maybe TE114. Probably not TM212 or TE213. I guess we'll see in the fields, if someone can get some numbers somehow....1) For 10.2 inches you should place the antenna to excite an electric excitation, because the resonance is transverse electric mode shape TE013 at 2.45GHz with L=10.2 inches. When you state that TM114 would be excited instead of TE013, does that mean that you placed the antenna to excite a magnetic instead of electric mode ? .2) Some time ago you were able to calculate with Meep the net force on the EM Drive. It would be most interesting if you could calculate the net force on the EM Drive at every finite difference time step for the cases of rfmwguy being studied, so that we can plot the force vs. time, and see what its time behavior looks like.There are indications in your plots that the force may not be a sine curve with time, and therefore that the force may sum up to a net amount over an integer number of periods, but we need numerical confirmation (or denial) of this.
Quote from: Rodal on 06/29/2015 12:01 am... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency, TM212 is 6.5% lower and TE213 is 9.2% lower. frequency. Using those estimates, Meep should have picked up TM114 (except I was exciting TE modes) and maybe TE114. Probably not TM212 or TE213. I guess we'll see in the fields, if someone can get some numbers somehow....
... I estimate (but I maybe wrong) that TM114's frequency is 0.8% higher than TE013, TE114 is 3.9% higher frequency, TM212 is 6.5% lower and TE213 is 9.2% lower. frequency.
All- To make it easier to search past threads, @Chris Bergin has given me permission to copy the contents of the locked forum threads 1 and 2 onto http://emdrive.wiki - see links at the bottom. I will do the same for thread 3 when it's locked and we graduate to thread 4.Each page takes a bit of time to render given the many external photos linked off, but the wiki Search function in the upper right, combined with "Control-F" within the page, should make it a lot to review previous posts. I find it fascinating that these threads actually began way back in 2012.
...Could you please lock the searchable NSF EM Drive threads in the wiki so that people are not able to edit and modify them? (people should be able to just view them and search them, the "Edit" page should not be available, particularly when it comes to modifying other people's comments).The way it is now, it looks like anyone can come and edit at will these NSF EM Drive threads in the wiki (I just tried and was able to access the Edit page of the searchable threads without trouble)
Quote from: rfmwguy on 06/29/2015 02:16 pmQuote from: Ricvil on 06/29/2015 01:09 pmI think the emdrive is just a axion thruster.The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by integration of the full stress-energy tensor.The frequency of the source must adjusted to match the condition of the ressonant backscattering.The em field is enclosed by the cavity but the axion not.Trouble with axions/dark matter, is its a non-detectable theoretical particle. Validation of thrust is what many of us are attempting now. Best we can do is eliminate other causes before theoretical particles...thus the tag line on all of my posts...Ricvil, welcome to the forum.The issue of axions was discussed in earlier threads. We even had an Astrophysicist (TMEubanks) involved in the discussion.Unfortunately, concerning an explanation, when we look at the numbers, things (including coupling) did not look goodThere are experiments that have been conducted over the last few years with microwave cavities to try to detect axions in this range. If the EM Drive force would be due to axions, it would mean that the physicists that have been looking for axions would need to be notified that Shawyer invented a more sensitive axion detector than the one they have been using, (Very unlikely), and the fact that if the EM Drive force is due to coupling with axions, how come axions have not been found despite using much more scientifically controlled experiments?
Quote from: Ricvil on 06/29/2015 01:09 pmI think the emdrive is just a axion thruster.The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by integration of the full stress-energy tensor.The frequency of the source must adjusted to match the condition of the ressonant backscattering.The em field is enclosed by the cavity but the axion not.Trouble with axions/dark matter, is its a non-detectable theoretical particle. Validation of thrust is what many of us are attempting now. Best we can do is eliminate other causes before theoretical particles...thus the tag line on all of my posts...
I think the emdrive is just a axion thruster.The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by integration of the full stress-energy tensor.The frequency of the source must adjusted to match the condition of the ressonant backscattering.The em field is enclosed by the cavity but the axion not.
Longitudinal Animation
Quote from: Chrochne on 06/29/2015 09:12 amI just read Mr. Traveller claim on reddit that the vibration increase the thrust of the EmDrive. May I ask you folks if there was already a debate about it here? I would be glad to read about it bit more. Did anybody here tried to increase the vibration in order to increase thrust? I would be glad to check that as well ....Link is here. The claim is in lower half of the thread.https://www.reddit.com/r/EmDrive/comments/3ah1ta/using_thetravellers_excel_emdrive_calculator/Thank you A claim is made based solely on what supposedly Shawyer said.The magnitude and frequency of the vibration that facilitates the measurement of the EM Drive is never addressed.Is the EM Drive an equal opportunity friend of all magnitudes and frequencies of vibration? This is implied, but it leads to absurd nonsense: is nanometer amplitude vibration enough ? How about picometer amplitude vibration? At what level the boundary between vibration in continuum mechanics and quantum mechanics uncertainty is breached ?How about frequency? Is 100 Hz sufficient? How about 0.0000000001 Hz? How about 10^100 Hz?...Statements like this serve to explain the controversy surrounding the EM Drive, and why it has made so little progress (despite the extravagant claims) in the 27 years (almost 3 decades) since Shawyer's 1988 patent application. A scientific approach is needed instead. Hopefully we will hear more news from NASA soon or get independent experimental data from well-constructed tests from the people in this thread.
I just read Mr. Traveller claim on reddit that the vibration increase the thrust of the EmDrive. May I ask you folks if there was already a debate about it here? I would be glad to read about it bit more. Did anybody here tried to increase the vibration in order to increase thrust? I would be glad to check that as well ....Link is here. The claim is in lower half of the thread.https://www.reddit.com/r/EmDrive/comments/3ah1ta/using_thetravellers_excel_emdrive_calculator/Thank you
Quote from: rfmwguy on 06/29/2015 02:23 pmQuote from: DrBagelBites on 06/29/2015 02:17 pmQuote from: WarpTech on 06/29/2015 01:26 pm...I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.ToddYou are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.Good ideas...if I am unable to secure a 100mW exciter today, its off to the magnetron store ;^)My only reservations on getting a magnetron is the inherent danger that comes with them, especially the beryllium oxide found on it. I think if it comes to it, I'll try and get my hands on an amplifier simply because it is safer. Speaking of which, what is the recommended power to start using a Faraday cage? I guess the obvious answer would be when you have to ask. But, I'm genuinely interested.
Quote from: DrBagelBites on 06/29/2015 02:17 pmQuote from: WarpTech on 06/29/2015 01:26 pm...I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.ToddYou are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.Good ideas...if I am unable to secure a 100mW exciter today, its off to the magnetron store ;^)
Quote from: WarpTech on 06/29/2015 01:26 pm...I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.ToddYou are probably correct. I am also using an 8W power source for my tests as well. I feel it is still worth looking into to see antenna placement/frequency/ etc effects and if thrust is actually able to be produced at that power. Of course if null results are found, another amplifier or a magnetron would be the next step.
...I think he needs to use a magnetron, or at least 100W amplifier. 8W isn't going to overcome the copper losses, the Q will be < 1, all loss and nothing stored. There is no evidence so far of any significant thrust with anything less than a magnetron.Todd
Microwaves can be highly focused and reflected. I'm even leary of cell phones. But more than considering what's in the faraday cage getting out, you need to consider keeping the outside interference from getting in. Plus, if you select a fine enough screen (copper screen from the hardware works well) it also helps with air circulation issues. So any power lever is a smart move for a faraday cage.Shell
Quote from: Rodal on 06/29/2015 11:22 amQuote from: Chrochne on 06/29/2015 09:12 amA claim is made based solely on what supposedly Shawyer said.The magnitude and frequency of the vibration that facilitates the measurement of the EM Drive is never addressed.Is the EM Drive an equal opportunity friend of all magnitudes and frequencies of vibration? This is implied, but it leads to absurd nonsense: is nanometer amplitude vibration enough ? How about picometer amplitude vibration? At what level the boundary between vibration in continuum mechanics and quantum mechanics uncertainty is breached ?How about frequency? Is 100 Hz sufficient? How about 0.0000000001 Hz? How about 10^100 Hz?...Statements like this serve to explain the controversy surrounding the EM Drive, and why it has made so little progress (despite the extravagant claims) in the 27 years (almost 3 decades) since Shawyer's 1988 patent application. A scientific approach is needed instead. Hopefully we will hear more news from NASA soon or get independent experimental data from well-constructed tests from the people in this thread.One note I would like to add on this subject: If Shawyer's em-drive does not produce any thrust in the absence of vibration then it will not work in outer space. Space is a vacuum and sound waves don't travel in space. There would be no vibrations to "stimulate" the em-drive.
Quote from: Chrochne on 06/29/2015 09:12 amA claim is made based solely on what supposedly Shawyer said.The magnitude and frequency of the vibration that facilitates the measurement of the EM Drive is never addressed.Is the EM Drive an equal opportunity friend of all magnitudes and frequencies of vibration? This is implied, but it leads to absurd nonsense: is nanometer amplitude vibration enough ? How about picometer amplitude vibration? At what level the boundary between vibration in continuum mechanics and quantum mechanics uncertainty is breached ?How about frequency? Is 100 Hz sufficient? How about 0.0000000001 Hz? How about 10^100 Hz?...Statements like this serve to explain the controversy surrounding the EM Drive, and why it has made so little progress (despite the extravagant claims) in the 27 years (almost 3 decades) since Shawyer's 1988 patent application. A scientific approach is needed instead. Hopefully we will hear more news from NASA soon or get independent experimental data from well-constructed tests from the people in this thread.
Quote from: SeeShells on 06/29/2015 04:31 pmMicrowaves can be highly focused and reflected. I'm even leary of cell phones. But more than considering what's in the faraday cage getting out, you need to consider keeping the outside interference from getting in. Plus, if you select a fine enough screen (copper screen from the hardware works well) it also helps with air circulation issues. So any power lever is a smart move for a faraday cage.ShellWas planning on just recording noise before testing, but you have a good point. Will look further into copper screen.-I
Quote from: Rodal on 06/29/2015 03:06 pmQuote from: rfmwguy on 06/29/2015 02:16 pmQuote from: Ricvil on 06/29/2015 01:09 pmI think the emdrive is just a axion thruster.The cavity can be thought as a corrugated waveguide ( by mirror simmetry) where a hybrid mode is the source of axion field ( E.B <> 0).The frequency used on the experiments are close to the models of light axions ( order of micro eletron-volts ~ 1.9 GHz).The point key the production and acceleration of axions could be some thing related with this:"Resonant radiation pressure on neutral particles in a waveguide"- arxiv.org/pdf/physics/0103017The article above talks about a ressonant backscattering of neutral particles, where under right conditions of frequency, a "arbitrarily small" polarizable scatter in a wave guide can have a huge effective scattering cross section.Well, the axion has the electrodynamic property of produce electromagnectic polarization due to axion-photon mixing.The conical geometry of cavity can produce a gradient intensity of the fields inside it, and resulting on a axial non symmetric scattering of axions (produced by the stationary wave of hybrid modes), and thus the thrust is formed.To comprove the hypotesis, a full time-domain numeric simulation of cavity fields using axion electrodynamic (em fields plus axion field) can be done (account to the non linearity), and net force can be estimated by integration of the full stress-energy tensor.The frequency of the source must adjusted to match the condition of the ressonant backscattering.The em field is enclosed by the cavity but the axion not.Trouble with axions/dark matter, is its a non-detectable theoretical particle. Validation of thrust is what many of us are attempting now. Best we can do is eliminate other causes before theoretical particles...thus the tag line on all of my posts...Ricvil, welcome to the forum.The issue of axions was discussed in earlier threads. We even had an Astrophysicist (TMEubanks) involved in the discussion.Unfortunately, concerning an explanation, when we look at the numbers, things (including coupling) did not look goodThere are experiments that have been conducted over the last few years with microwave cavities to try to detect axions in this range. If the EM Drive force would be due to axions, it would mean that the physicists that have been looking for axions would need to be notified that Shawyer invented a more sensitive axion detector than the one they have been using, (Very unlikely), and the fact that if the EM Drive force is due to coupling with axions, how come axions have not been found despite using much more scientifically controlled experiments?As a practical example of using Saucyjack's incorporation of the NSF threads into the EM Drive wiki to make them searchable, I looked for "Axions", and I immediately found this great post by Astrophysicist TMEubanks (lots of information in a few lines):Title: Re: EM Drive Developments - related to space flight applications - Thread 2 Post by: TMEubanks on 02/15/2015 06:30 PMThoughts on Axions. (I apologize if this has been already covered.)The question as to whether the EM Drive could be coupling to the Axion background came up on a different forum. I am dubious, and thought it would be useful to post why. A recent review of axions as CDM: http://www.pnas.org/.../2015/01/07/1308788112.full.pdf Current constraints on the axion mass constrain it to be in the range ~ 1 - 1000 micro-eV, and a 2 GHz axion would correspond to 8.2 micro-eV, so that's OK, maybe the EM drive couples to the axion mass. But, check out the Axion Dark-Matter Experiment in the PNAS article. That is much much more sensitive than the EM Drive - they are looking for yoctowatts (10^-24) of RF power in the 2 - 20 micro-eV range, precisely the range of the EM Drive, by tuning the cavity's resonant frequency to the axion mass. There is simply no way that the Drive is coupling to the axion background - the ADMX would see a whopping signal. Now, maybe the ADMX is producing lots of axions, at a low enough velocity to evade the photon rocket limits. That would mean that the EM Drive can convert watts of RF -> axions, while the ADMX is NOT converting 10^-24 watts of dark matter axions -> RF power. While I guess it is possible, I just don't buy it. Nobody is accidentally lucky by 20+ orders of magnitude. (Note also that the theory is pretty clear here - if axions have these kinds of 1 - 10 micro-eV masses, they will supply most or all of the DM, so there will be a background.)
Views of NSF-1701 are up:https://drive.google.com/folderview?id=0B1XizxEfB23tfklENXg2TWhrbUhneGxZQzJ0VVhkRFRwUUhCN2xKX24yOGM2bFQzdVV5NlE&usp=sharingThis file shows the 18 views of the E and H components from x, y and z directions.This is from a Meep model of rfmwguy's 10.2 inch cavity, in copper, driven by a 2.45000 GHz continuous Ez source. The resonant frequency of this cavity is somewhere close to 2.45 GHz but no resonance solutions indicate exactly 2.45 GHz. The continuous source used in this model is ideal and exact. There are no "shoulders" on the input power source, all input energy is at exactly the drive frequency, 2.45 GHz. The antenna model, a dipole, is oriented perpendicular to the central axis of rotation, one-half wavelength from the small end, and is 0.058 meters long.An important point is to note that these views use a fixed Max/Min range of power/color intensity. I'll leave it to the experts to analyse the characteristics shown.
Quote from: smartcat on 06/25/2015 01:55 amQuote from: OttO on 06/24/2015 08:51 amI am not a Shawyer fan but the Traveller defense could be not so crazy, look at the following paper:Motion induced radiation from a vibrating cavityhttp://arxiv.org/abs/quant-ph/9606029We study the radiation emitted by a cavity moving in vacuum. We give a quantitative estimate of the photon production inside the cavity as well as of the photon flux radiated from the cavity. A resonance enhancement occurs not only when the cavity length is modulated but also for a global oscillation of the cavity. For a high finesse cavity the emitted radiation surpasses radiation from a single mirror by orders of magnitude.Amazing!.. Is this IT then?!The paper is referring to the Dynamic Casimir effect, which has required a SQUID to produce the effect experimentally. The copper walls of the EM Drive are not moving anywhere close to the required speed.Here is a mechanical device with high Q that has mechanical vibration in the GHz range: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.152.4917&rep=rep1&type=pdfsee how much smaller than the EM Drive's tested by researchers it is: 20µm-diameter = 14,000 times smaller diameter than the EM Drive 2µm-stemstem offset from the center by only 1µm
Quote from: OttO on 06/24/2015 08:51 amI am not a Shawyer fan but the Traveller defense could be not so crazy, look at the following paper:Motion induced radiation from a vibrating cavityhttp://arxiv.org/abs/quant-ph/9606029We study the radiation emitted by a cavity moving in vacuum. We give a quantitative estimate of the photon production inside the cavity as well as of the photon flux radiated from the cavity. A resonance enhancement occurs not only when the cavity length is modulated but also for a global oscillation of the cavity. For a high finesse cavity the emitted radiation surpasses radiation from a single mirror by orders of magnitude.Amazing!.. Is this IT then?!
I am not a Shawyer fan but the Traveller defense could be not so crazy, look at the following paper:Motion induced radiation from a vibrating cavityhttp://arxiv.org/abs/quant-ph/9606029We study the radiation emitted by a cavity moving in vacuum. We give a quantitative estimate of the photon production inside the cavity as well as of the photon flux radiated from the cavity. A resonance enhancement occurs not only when the cavity length is modulated but also for a global oscillation of the cavity. For a high finesse cavity the emitted radiation surpasses radiation from a single mirror by orders of magnitude.
One note I would like to add on this subject: If Shawyer's em-drive does not produce any thrust in the absence of vibration then it will not work in outer space. Space is a vacuum and sound waves don't travel in space. There would be no vibrations to "stimulate" the em-drive.