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.
If I am correct and if MEEP is able to simulate Wood anomalies (plasmons), we could end with one OUTSIDE end surface of the frustum less reflective than the other to microwaves.http://cpb.iphy.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=26571
Quote from: WarpTech on 06/29/2015 04:42 amI know how you feel, but I just found out that the surface resistance of copper at 2.4GHz is supposedly,RS = 0.013 Ohms. From this, you can get the power losses as the integral over the internal surface area,P_loss = ∮S(RS*|H|2)*dS, Basically Ohm's law.That's a pretty high resistance, so a 100mW source will hardly overcome the copper losses. Based on the heating reported, the losses are in the "watts" range at high Q. I'm sure you will need a stronger source. ToddI think he is planning on using an amplifier to up power to 8W, I believe.
I know how you feel, but I just found out that the surface resistance of copper at 2.4GHz is supposedly,RS = 0.013 Ohms. From this, you can get the power losses as the integral over the internal surface area,P_loss = ∮S(RS*|H|2)*dS, Basically Ohm's law.That's a pretty high resistance, so a 100mW source will hardly overcome the copper losses. Based on the heating reported, the losses are in the "watts" range at high Q. I'm sure you will need a stronger source. Todd
If you can see/think another useful way to try to visualize these I'll see what I can do! I don't understand really what I'm looking at, just processing the pictures Are these different cross sections (I think they are)? I could build a semi-transparent 3d animated cross section (I think I can anyway!)...
Quote from: Rodal on 06/29/2015 11:29 am...They are cross-sections of a truncated cone. ...///////////////////If you could construct 3D plots out of this information, that would be great.The numerical data from which the plots were made should be available from aero, as all plots are constructed from numerical data.Does/Can MEEP output the data in a 3D x/y/z/strength comma separated value file? I would then be able to create a 3D plot of semi-transparent 'voxels' (bricks inside a volume) in a graphic ray-tracing program and then animate that output. It would be beautiful It would take me a few days to do the first one (just to do the coding in POVRay for the pictures), but the next one would take an hour.
...They are cross-sections of a truncated cone. ...///////////////////If you could construct 3D plots out of this information, that would be great.The numerical data from which the plots were made should be available from aero, as all plots are constructed from numerical data.
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 ?
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.
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.
...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
Quote from: deuteragenie on 06/29/2015 01:11 pmQuote 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 ?I think that the force should be computed from surface integration of Maxwell's stress tensor . The stress tensor components are force/area. It is a tensor because the force has different components in different directions (basically force perpendicular to the area and force components tangential to the area, and the area has different normal vectors according to its orientation). My recollection is that aero referred to it as "force", as to how he computed it, only he can tell.The link you provide shows how, through energy and photon-number conservation (*), one can show that knowledge of the phase and the amplitude response of an optomechanically variable system, and its dependence on the mechanical coordinate of interest, is sufficient to compute the forces produced by light. This formalism offers a simple analytical alternative to the correct, but computationally intensive Maxwell stress-tensor methods.As to whether this alternative is applicable, and how accurately, for the EM Drive (*), I have not had the time to check. It is important that the algorithm you point to, purely to save computer time and avoid dealing with Maxwell's stress tensor, is making an assumption regarding entropy, since S is proportional to N (*).__________(*) The photon number and the internal energy are NOT conserved in a photon gas, instead, it increases strongly with temperature, see https://en.wikipedia.org/wiki/Photon_gas
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.
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: 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.Hello Everyone! Long time lurker (since the first original thread!) and first time poster now.DrBagelBites: It appears to me that you are trying to perform the experiments in a non intuitive manner. Wouldn't it be better to first validate the effect using the given details from Shawyer/Rodal et al and then move into different power ranges, such as the 8W that is being attempted? To me it sounds like you are trying to work out the power ranges without first validating the principle of operation, even if there isn't a valid theory for its operation as of yet. I thought the whole point of replication was to replicate the exact phenomenon using the same equipment construction and measurement techniques. Just my 2 cents.
(*) The photon number and the internal energy are NOT conserved in a photon gas, instead, it increases strongly with temperature, see https://en.wikipedia.org/wiki/Photon_gas
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 02:31 pmQuote 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.BeO is actually safe, I've been around it alot in my past life...its only when you convert it into particulates, such as drilling into it that can cause problems. Even knew a sales gal once that had BeO earrings that she wore to show how safe it is. She worked for a ceramics company. Just don't drill into it...lung exposure is the risk.We put RF radiation up to our ears every day using cellphones at 2W and below. There is a lot of controversy on how much a person can tolerate. However, microwaves cook meat, that means you and me. Faraday the thing 100% of the time is my advice.Edit stoopid typos...
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...