Is this right? This looks to me like bad science. How could thrust fall as speed increases? I also looked to "scientific" paper on emdrive page and there is stated that at about 0.7c thrust reverses? http://emdrive.com/sciencemissions.html...
Hi Everyone,I am an RF engineer in the Microwave Instrument Technology Branch at NASA Goddard Space Flight Center. I had seen a few articles here and there about the EM drive and today it caught my eye on IO9.com. While I have only spent the last hour or so reviewing what has been done to eliminated external factors to explain the phenomenon I would like to offer my two-cents. If what I'm suggesting as an explanation has already been eliminated, I apologize.Have you considered the effects of breakdown, and in particular multipaction and corona generation? Multipaction breakdown events are known phenomenon on the RF radar and communication systems community. Essentially, at high RF powers you see an effect similar to arcing within your components. This arcing can occur between conductors and dielectrics or even between conductors in vacuum. Sharp edges such as welds and fasteners - particularly in a cavity resonator such as this - can cause these events. This result is damage to the interior conductor and particle generation (even in metal-only situations) as material is "burned." In this case, the metal walls and / or contaminants of your cavity would serve as the propellant. Corona / plasma can then develop from this particle release and exacerbate the situation.Better descriptions can be found here : http://en.wikipedia.org/wiki/Multipactor_effecthttp://www.microwaves101.com/encyclopedias/multipaction As a real world example, I am the lead engineer for the Radiometer Front End on the recently launched Soil Moisture Active Passive (SMAP) Mission. (http://smap.jpl.nasa.gov/) We had a terrible problem with multipaction in our RF diplexer which was a cavity resonator - similar to your setup. These devices are essentially three-port band-pass filters whose resonant frequencies are set by the physical dimensions of the (mostly) empty cavity. Picture an empty aluminum box about 10'' x 5'' x 5''. We saw damaging breakdown events beginning around 350W at 1.2GHz which is the nominal operating point of our radar. It took several design iterations and many months to totally eliminate various sources of breakdown including sharp edges, gas trapped by resonator pucks, tuning screws, etc. While your cavity and ours arn't exactly the same one could say the situations are quite similar. The NASA Eagleworks system operated at 935MHz at (?)W, Roger Shawyer 2.45GHz at 850W, and Dr Yang at (?)MHz at 2.5KW (apologize if these missing values have been published, I didn't immediately see them). In a nutshell, at these power levels I would be surprised if your systems were not multipacting to some degree as designing a cavity that does not have breakdown at these levels takes a good deal of expertise on the nuances of the issue. So as multipaction events are particle generators these could produce the force you are seeing. What order of magnitude force we would see I havn't the foggiest. But if I were an independent reviewer of your technology I would first ask that you prove this cannot be explained by multipaction. Or show that even if multipaction were occuring the magnitude of the forces involved cannot be explained. These events can be observed by monitoring the RF power level passing through, or in your case reflecting, from a system. An ideal setup would be to add an RF coupler between your magnetron and the cavity and observe the return loss into the system as power is slowly ramped up. You will see a reflected power loss as the energy is converted into the events described. A further test would be to have your resonator opened and carefully inspected by an expert as burn marks and other evidence can be detected optically. Good luck, I can pass you some names off-line if that is of interest. If you havn't already, it would be useful to consult a high-power RF engineer, not necessarily and EM physicist (sorry guys! ). As stated, I am not an expert on this phenomenon but if there are further questions I can perhaps pass them along.-Joseph Knuble(Also, I hope I'm wrong!)
Quote from: jknuble on 05/01/2015 06:33 pmGood luck, I can pass you some names off-line if that is of interest. If you havn't already, it would be useful to consult a high-power RF engineer, not necessarily and EM physicist (sorry guys! ). As stated, I am not an expert on this phenomenon but if there are further questions I can perhaps pass them along.-Joseph Knuble(Also, I hope I'm wrong!)Welcome to the thread We hope you are here to stay Please correct me if I'm wrong, but my understanding of this effect is that the multipactor effect occurs "when electrons accelerated by radio-frequency (RF) fields are self-sustained in a vacuum (or near vacuum)"The counter-argument to this is that most of the EM Drive experiments have been conducted in ambient conditions (not in a vacuum).
Good luck, I can pass you some names off-line if that is of interest. If you havn't already, it would be useful to consult a high-power RF engineer, not necessarily and EM physicist (sorry guys! ). As stated, I am not an expert on this phenomenon but if there are further questions I can perhaps pass them along.-Joseph Knuble(Also, I hope I'm wrong!)
Ok guys, so a lot of new people into this thread, but this thread is mainly for the development of the EM Drive. We knew this would happen, so we have a new "Entry Level" thread for opening questions and general questions.I've moved the last few pages of new members asking questions into that thread, so if you posted here and can't see it, don't worry, it's in this thread.http://forum.nasaspaceflight.com/index.php?topic=37438.0Posting this notice as some sites are linking to this thread and not the section or the article, so people are thinking this is the only thread on this. Remember to use the above link and allow this thread to continue with the Eaglework folk and others updating progress.
Quote from: Andy USA on 05/02/2015 12:05 amOk guys, so a lot of new people into this thread, but this thread is mainly for the development of the EM Drive. We knew this would happen, so we have a new "Entry Level" thread for opening questions and general questions.I've moved the last few pages of new members asking questions into that thread, so if you posted here and can't see it, don't worry, it's in this thread.http://forum.nasaspaceflight.com/index.php?topic=37438.0Posting this notice as some sites are linking to this thread and not the section or the article, so people are thinking this is the only thread on this. Remember to use the above link and allow this thread to continue with the Eaglework folk and others updating progress.I think we need a F.A.Q.
Quote from: R.W. Keyes on 05/02/2015 01:55 amQuote from: Andy USA on 05/02/2015 12:05 amOk guys, so a lot of new people into this thread, but this thread is mainly for the development of the EM Drive. We knew this would happen, so we have a new "Entry Level" thread for opening questions and general questions.I've moved the last few pages of new members asking questions into that thread, so if you posted here and can't see it, don't worry, it's in this thread.http://forum.nasaspaceflight.com/index.php?topic=37438.0Posting this notice as some sites are linking to this thread and not the section or the article, so people are thinking this is the only thread on this. Remember to use the above link and allow this thread to continue with the Eaglework folk and others updating progress.I think we need a F.A.Q.Yes, if the EM Drive thread would be about well-understood science and/or engineering, an FAQ section would be great.We all want answers, that's why we are here.Unfortunately there is substantial amount of disagreement as to the measurements and even more disagreement about the theories.Who is going to be in charge of answering the questions? Are (maybe innocently incorrect or innocently misleading) answers provided by forum volunteers for an unsettled, controversial, Research project like the EM Drive more useful than not having an FAQ section?How can a FAQ section for unsettled Research in a forum be objectively handled for scientific/engineering accuracy? Who will give an authoritative answer in a forum? How is misinformation going to be prevented? How is agreement on what is the correct answer to a question going to be reached?
Quote from: Rodal on 05/02/2015 02:19 amQuote from: R.W. Keyes on 05/02/2015 01:55 amQuote from: Andy USA on 05/02/2015 12:05 amOk guys, so a lot of new people into this thread, but this thread is mainly for the development of the EM Drive. We knew this would happen, so we have a new "Entry Level" thread for opening questions and general questions.I've moved the last few pages of new members asking questions into that thread, so if you posted here and can't see it, don't worry, it's in this thread.http://forum.nasaspaceflight.com/index.php?topic=37438.0Posting this notice as some sites are linking to this thread and not the section or the article, so people are thinking this is the only thread on this. Remember to use the above link and allow this thread to continue with the Eaglework folk and others updating progress.I think we need a F.A.Q.Yes, if the EM Drive thread would be about well-understood science and/or engineering, an FAQ section would be great.We all want answers, that's why we are here.Unfortunately there is substantial amount of disagreement as to the measurements and even more disagreement about the theories.Who is going to be in charge of answering the questions? Are (maybe innocently incorrect or innocently misleading) answers provided by forum volunteers for an unsettled, controversial, Research project like the EM Drive more useful than not having an FAQ section?How can a FAQ section for unsettled Research in a forum be objectively handled for scientific/engineering accuracy? Who will give an authoritative answer in a forum? How is misinformation going to be prevented? How is agreement on what is the correct answer to a question going to be reached?Maybe you should elect the most hardcore and knowledgeable proponent and the most hardcore and knowledgeable critic and produce two answers to each question.
additional, federal money.
If Eagleworks thinks this is a bad approach to obtaining additional resources, please let me know why.
This is a question for Eagleworks people:It seems as though you are short of resources of various types. I propose an online petition, utilizing the "we the people" facility of whitehouse.gov, to ask for more resources to be given to NASA, earmarked for Eagleworks, for the projects of the EM-drive/ME-drive/Q-thruster, and its application to the Alcubierre drive. If you could come up with a proposal, perhaps more focused than I've indicated, this would be the meat of the petition.I don't mean to over the heads of the NASA Administration, and force them to take money away from other programs for this one. This would be additional, federal money. In my experience, being given more resources than you can use raises expectations beyond what is achievable. Most often, you can't get a project done twice as fast by spending twice as much money on it.If Eagleworks thinks this is a bad approach to obtaining additional resources, please let me know why.With great respect,Robert W. Keyes
Quote from: JoeOfTex on 05/01/2015 03:41 pmI am assuming the microwaves path is something like this?Where forces F0 through F16 represent the force of a single microwave at different time intervals.If the directional force happens at F2, and the opposing force happens from F3 to F16, this still obeys Newtons third law. Isn't the opposing force just being damped like a spring over time? If M1, M2, ... Mn represent different microwaves, and each Mi is following a similar course, wouldn't this suggest that the directional force will remain positive at a constant rate until the device is shut off causing all forces to cancel? Not according to Maxwell's linear, isotropic equations.The small base of the EM Drive is not open. It is a closed cavity. As such, the waves inside it are not travelling waves, but standing waves. See this: http://en.wikipedia.org/wiki/Standing_waveThe energy flux is pointed towards one end during half a (Poynting vector) period and it is pointed towards the opposite end during the next half-period. Hence the net energy flux over a whole period is completely self-cancelling.No net directional thrust for a microwave closed cavity can be explained just using Maxwell's linear, isotropic equations. If the measurements are not an experimental artifact, another explanation is needed.If the small base would be open, then it would be an inefficient photon rocket, with the microwave photons escaping at the small base end. Less efficient for space propulsion than using a flashlight or a military searchlight as a means of propulsion.Even for a perfectly collimated photon rocket, the thrust/powerInput of such a photon rocket is orders of magnitude less than what is claimed for these experiments.
I am assuming the microwaves path is something like this?Where forces F0 through F16 represent the force of a single microwave at different time intervals.If the directional force happens at F2, and the opposing force happens from F3 to F16, this still obeys Newtons third law. Isn't the opposing force just being damped like a spring over time? If M1, M2, ... Mn represent different microwaves, and each Mi is following a similar course, wouldn't this suggest that the directional force will remain positive at a constant rate until the device is shut off causing all forces to cancel?
Quote from: Rodal on 05/01/2015 03:53 pmQuote from: JoeOfTex on 05/01/2015 03:41 pmI am assuming the microwaves path is something like this?Where forces F0 through F16 represent the force of a single microwave at different time intervals.If the directional force happens at F2, and the opposing force happens from F3 to F16, this still obeys Newtons third law. Isn't the opposing force just being damped like a spring over time? If M1, M2, ... Mn represent different microwaves, and each Mi is following a similar course, wouldn't this suggest that the directional force will remain positive at a constant rate until the device is shut off causing all forces to cancel? Not according to Maxwell's linear, isotropic equations.The small base of the EM Drive is not open. It is a closed cavity. As such, the waves inside it are not travelling waves, but standing waves. See this: http://en.wikipedia.org/wiki/Standing_waveThe energy flux is pointed towards one end during half a (Poynting vector) period and it is pointed towards the opposite end during the next half-period. Hence the net energy flux over a whole period is completely self-cancelling.No net directional thrust for a microwave closed cavity can be explained just using Maxwell's linear, isotropic equations. If the measurements are not an experimental artifact, another explanation is needed.If the small base would be open, then it would be an inefficient photon rocket, with the microwave photons escaping at the small base end. Less efficient for space propulsion than using a flashlight or a military searchlight as a means of propulsion.Even for a perfectly collimated photon rocket, the thrust/powerInput of such a photon rocket is orders of magnitude less than what is claimed for these experiments.With all respect, and I am not sure this is much of an issue to point out but I think the model of the waves in the cavity as standing waves may be a bit over-simplified. 1. I think one can look at standing waves as super-imposed traveling waves of opposite direction but this part is likely less significant. 2. Maybe of more significance is the ac power in power lines can be modeled as standing waves but if no one is using power. When power starts being consumed the standing waves begin to travel towards the object consuming the power. The moving bulges of magnetic/electric field can be thought of as transporting power from the power station to the consumer. There should be some traveling of the standing waves bulges from the power supply towards areas of heat loss in the cavity I would assume. I can't say the power dissipated into heat loss is significant but it does seem to buck the perfect standing wave view for me a bit. I do understand on the other hand that it may be a good approximation.
Quote from: Mulletron on 04/19/2015 08:08 pmQuote from: Star-Drive on 04/19/2015 04:44 pmDr. Rodal:I missed your question last night on whether the warp-field interferometer cylindrical cavity had any dielectric inside of it. The answer is no it does not, except for the nanometers thick aluminum oxide coating that bare aluminum develops as soon as it is exposed to the oxygen in the air.Next you asked about whether there where optical windows cut into the center of the cylindrical resonant cavity end caps or not. Well, yes there has to be optical window holes for the 633nm laser light to pass through the 7.23cm gap between the endplates of the aluminum cylindrical cavity. We also added two, three inch long, 0.50" OD by 0.25" (6.35mm) ID threaded aluminum tubes to the resonant cavity endplates, see attached picture, that function as two RF chokes that keep the 1.48 GHz RF from leaking into the lab area. So the laser light passes through these RF choke tubes and the cylindrical cavity where the peak ac E-field of 900kV/m is present along the entire 7.23 cm long laser path while in the resonant cavity and an exponentially reducing E-field in the RF chokes since these are cylindrical waveguides well into their cutoff mode since the RF wavelength at 1.48 GHz is 202.7mm. BTW, we are going to add optical borosilicate telescope grade flat windows to the ends of the RF chokes when we get around to pulling a vacuum in this 1.48 GHz resonant cavity.Next a clarification. We used a cylindrical cavity for the warp-field interferometer instead of a frustum shape because we didn't want to create a force with this unit, but instead we needed just a large densification of the Q-V along the active path length of the laser beam while it was traversing the resonant cavity's centerline volume. And this is the main difference between the Q-thruster and a warp-drive. In Dr. White's warp-field conjecture you first have to have an Q-Thruster derived acceleration vector to work on and then you engage the a toroidal warp-field around your accelerating vehicle that then multiples the initial Q-Thruster provided velocity vector by the selected warp-factor. Thus if you have an initial velocity of say 0.01c towards Alpha Centauri with a warp factor of 1,000, your effective velocity becomes 10c while the warp-drive is engaged.Best, Paul M.Paul March, have you seen this?http://arxiv.org/abs/1101.0712http://arxiv.org/abs/1101.1174http://www2.cnrs.fr/en/1859.htmhttp://phys.org/news/2011-05-when-the-speed-of-light.html
Quote from: Star-Drive on 04/19/2015 04:44 pmDr. Rodal:I missed your question last night on whether the warp-field interferometer cylindrical cavity had any dielectric inside of it. The answer is no it does not, except for the nanometers thick aluminum oxide coating that bare aluminum develops as soon as it is exposed to the oxygen in the air.Next you asked about whether there where optical windows cut into the center of the cylindrical resonant cavity end caps or not. Well, yes there has to be optical window holes for the 633nm laser light to pass through the 7.23cm gap between the endplates of the aluminum cylindrical cavity. We also added two, three inch long, 0.50" OD by 0.25" (6.35mm) ID threaded aluminum tubes to the resonant cavity endplates, see attached picture, that function as two RF chokes that keep the 1.48 GHz RF from leaking into the lab area. So the laser light passes through these RF choke tubes and the cylindrical cavity where the peak ac E-field of 900kV/m is present along the entire 7.23 cm long laser path while in the resonant cavity and an exponentially reducing E-field in the RF chokes since these are cylindrical waveguides well into their cutoff mode since the RF wavelength at 1.48 GHz is 202.7mm. BTW, we are going to add optical borosilicate telescope grade flat windows to the ends of the RF chokes when we get around to pulling a vacuum in this 1.48 GHz resonant cavity.Next a clarification. We used a cylindrical cavity for the warp-field interferometer instead of a frustum shape because we didn't want to create a force with this unit, but instead we needed just a large densification of the Q-V along the active path length of the laser beam while it was traversing the resonant cavity's centerline volume. And this is the main difference between the Q-thruster and a warp-drive. In Dr. White's warp-field conjecture you first have to have an Q-Thruster derived acceleration vector to work on and then you engage the a toroidal warp-field around your accelerating vehicle that then multiples the initial Q-Thruster provided velocity vector by the selected warp-factor. Thus if you have an initial velocity of say 0.01c towards Alpha Centauri with a warp factor of 1,000, your effective velocity becomes 10c while the warp-drive is engaged.Best, Paul M.Paul March, have you seen this?http://arxiv.org/abs/1101.0712http://arxiv.org/abs/1101.1174http://www2.cnrs.fr/en/1859.htmhttp://phys.org/news/2011-05-when-the-speed-of-light.html
Dr. Rodal:I missed your question last night on whether the warp-field interferometer cylindrical cavity had any dielectric inside of it. The answer is no it does not, except for the nanometers thick aluminum oxide coating that bare aluminum develops as soon as it is exposed to the oxygen in the air.Next you asked about whether there where optical windows cut into the center of the cylindrical resonant cavity end caps or not. Well, yes there has to be optical window holes for the 633nm laser light to pass through the 7.23cm gap between the endplates of the aluminum cylindrical cavity. We also added two, three inch long, 0.50" OD by 0.25" (6.35mm) ID threaded aluminum tubes to the resonant cavity endplates, see attached picture, that function as two RF chokes that keep the 1.48 GHz RF from leaking into the lab area. So the laser light passes through these RF choke tubes and the cylindrical cavity where the peak ac E-field of 900kV/m is present along the entire 7.23 cm long laser path while in the resonant cavity and an exponentially reducing E-field in the RF chokes since these are cylindrical waveguides well into their cutoff mode since the RF wavelength at 1.48 GHz is 202.7mm. BTW, we are going to add optical borosilicate telescope grade flat windows to the ends of the RF chokes when we get around to pulling a vacuum in this 1.48 GHz resonant cavity.Next a clarification. We used a cylindrical cavity for the warp-field interferometer instead of a frustum shape because we didn't want to create a force with this unit, but instead we needed just a large densification of the Q-V along the active path length of the laser beam while it was traversing the resonant cavity's centerline volume. And this is the main difference between the Q-thruster and a warp-drive. In Dr. White's warp-field conjecture you first have to have an Q-Thruster derived acceleration vector to work on and then you engage the a toroidal warp-field around your accelerating vehicle that then multiples the initial Q-Thruster provided velocity vector by the selected warp-factor. Thus if you have an initial velocity of say 0.01c towards Alpha Centauri with a warp factor of 1,000, your effective velocity becomes 10c while the warp-drive is engaged.Best, Paul M.
Quote from: Star-Drive on 04/19/2015 10:00 pmMulletron:No I hadn't but thanks for the pointers. So what to you think an asymmetric difference of ~1x10^-18 m/s in velocity of light bring to the table? That the vacuum can be differentially polarized by applied E and B-fields in a volume, in this case dc E&M fields??Best, Paul M.Their results seem to support what you guys are reporting from your open air experiments, which is a win, but I don't think we can call this length contraction (even though it might look like it) for sure until the same results are in repeated in vacuum.
Mulletron:No I hadn't but thanks for the pointers. So what to you think an asymmetric difference of ~1x10^-18 m/s in velocity of light bring to the table? That the vacuum can be differentially polarized by applied E and B-fields in a volume, in this case dc E&M fields??Best, Paul M.