The question I have is why TM010 vs say TM013?
Craig:The one thing you need to understand is that the off-the-shelf 929 MHz XXXkW magnetrons won't work very well with a high-Q copper frustum due to its nominal very wide bandwidth, which means that most of its RF input power would be wasted heating the cavity walls instead of maximizing the generated E&M fields. At room temperature, a copper frustum driving a TE013 resonant response has a resonant -3dB bandwidth of say 30 kHz where as the magnetron's normal output is smeared over 30 to 60 MHz dependent on its design and operating temperature. However, what one can do is to modify the magnetron along the lines in the attached slide so that it becomes a controllable frequency source with similar -3dB bandwidth that can be CONTROLLED with an S11 resonant frequency tracker with force feedback as I was talking about with The Traveler (Phil).BTW, we still don't know what resonant mode will generate the best thruster efficiency other than high Q-factors, to a point, are better. The reason I had Jerry Vera run these COMSOL/QV-Plasma code simulations at the TM010 resonant mode frequency was that we already had the COMSOL results for the EW copper frustum and it had a TM010 resonant frequency close to the 929 MHz output of this L-3 Comm 100kW magnetron with 88% efficiency. From the testing experience of Shawyer and others, the best frustum resonant mode may be to run the cavity at its TE013 resonance, which means purpose building a copper frustum with its as-built TE013 resonance at 929 MHz and one that can handle the 12+kW of power dissipation. Best,
... L-3 was to send me dimensions (I used the Travellers spreadsheet to come up with some rough dimensions to confirm) but then they stopped emailing me after sending pictures
Quote from: WarpTech on 11/23/2016 03:40 pmQuote from: Star-Drive on 11/23/2016 03:27 pmQuote from: WarpTech on 11/23/2016 03:04 pmI have considered the MHD model for many, many years. My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin. If e-p pairs in the frustum had a density ~1x1012 kg/m3, and a life time of ~10-22 s, the frustum would be vaporized from the heat, faster than dropping it onto the surface of the sun.The paper in JBIS is saying that it would require a mass of e-p pairs in excess of 105 kg. So the heat and the mass would not go undetected, therefore that's not it.Regarding the paper you attached, I love this paper! However, at the scale of electrons and quarks, they are constantly undergoing exchange scattering with their counterparts in the QV. At this scale it is possible because the E field exceeds the Schwinger limit, but in the frustum the E field is no where near that limit. So the expectation of producing so many pairs is unreasonable, and I offer that it can't be happening if the frustum is not melting instantly upon their creation.ToddTodd:"My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin."Again you are making the assumption that the e/p pairs are fully fleshed out in our universe, which does require 0.511 MeV per particle and that would indeed melt the frustum if fully developed. What Dr. White's QV conjecture posits is that these virtual force carriers can be expressed in our reality with a variable effective mass/energy density that goes from just barely here to fully here at the Schwinger limit energy densities. Of course the only way to prove this QV conjecture is to test a given frustum design over a broad input power range of four orders of magnitude or greater to see if it generates the COMSOL/QV Plasma code's EW copper frustum's TM010 thrust predictions I posted at NSF.com earlier, or not.Best, Paul M. I've read this idea a very long time ago, but I thought it was discredited because I never heard of it again. If that is the case, a much simpler experiment would be to measure the "linearity" of vacuum permittivity and permeability up to fields strengths equivalent to those in the frustum. Because, any such creation of virtual pairs, or voltage tension between two virtual masses, will change the permittivity and permeability of the vacuum in a measurable way. How non-linear are vacuum filled capacitors as the field strength approaches 10^7 V/m?See the attached paper by Urban, which derives these values from the polarizable vacuum. We could probably extend this to apply directly to such an experiment.Todd:Great idea and thanks much for the pointer to the Urban paper! I will read and consider how one might do this on the cheap in my home lab once it is built. Best, Paul M.
Quote from: Star-Drive on 11/23/2016 03:27 pmQuote from: WarpTech on 11/23/2016 03:04 pmI have considered the MHD model for many, many years. My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin. If e-p pairs in the frustum had a density ~1x1012 kg/m3, and a life time of ~10-22 s, the frustum would be vaporized from the heat, faster than dropping it onto the surface of the sun.The paper in JBIS is saying that it would require a mass of e-p pairs in excess of 105 kg. So the heat and the mass would not go undetected, therefore that's not it.Regarding the paper you attached, I love this paper! However, at the scale of electrons and quarks, they are constantly undergoing exchange scattering with their counterparts in the QV. At this scale it is possible because the E field exceeds the Schwinger limit, but in the frustum the E field is no where near that limit. So the expectation of producing so many pairs is unreasonable, and I offer that it can't be happening if the frustum is not melting instantly upon their creation.ToddTodd:"My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin."Again you are making the assumption that the e/p pairs are fully fleshed out in our universe, which does require 0.511 MeV per particle and that would indeed melt the frustum if fully developed. What Dr. White's QV conjecture posits is that these virtual force carriers can be expressed in our reality with a variable effective mass/energy density that goes from just barely here to fully here at the Schwinger limit energy densities. Of course the only way to prove this QV conjecture is to test a given frustum design over a broad input power range of four orders of magnitude or greater to see if it generates the COMSOL/QV Plasma code's EW copper frustum's TM010 thrust predictions I posted at NSF.com earlier, or not.Best, Paul M. I've read this idea a very long time ago, but I thought it was discredited because I never heard of it again. If that is the case, a much simpler experiment would be to measure the "linearity" of vacuum permittivity and permeability up to fields strengths equivalent to those in the frustum. Because, any such creation of virtual pairs, or voltage tension between two virtual masses, will change the permittivity and permeability of the vacuum in a measurable way. How non-linear are vacuum filled capacitors as the field strength approaches 10^7 V/m?See the attached paper by Urban, which derives these values from the polarizable vacuum. We could probably extend this to apply directly to such an experiment.
Quote from: WarpTech on 11/23/2016 03:04 pmI have considered the MHD model for many, many years. My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin. If e-p pairs in the frustum had a density ~1x1012 kg/m3, and a life time of ~10-22 s, the frustum would be vaporized from the heat, faster than dropping it onto the surface of the sun.The paper in JBIS is saying that it would require a mass of e-p pairs in excess of 105 kg. So the heat and the mass would not go undetected, therefore that's not it.Regarding the paper you attached, I love this paper! However, at the scale of electrons and quarks, they are constantly undergoing exchange scattering with their counterparts in the QV. At this scale it is possible because the E field exceeds the Schwinger limit, but in the frustum the E field is no where near that limit. So the expectation of producing so many pairs is unreasonable, and I offer that it can't be happening if the frustum is not melting instantly upon their creation.ToddTodd:"My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin."Again you are making the assumption that the e/p pairs are fully fleshed out in our universe, which does require 0.511 MeV per particle and that would indeed melt the frustum if fully developed. What Dr. White's QV conjecture posits is that these virtual force carriers can be expressed in our reality with a variable effective mass/energy density that goes from just barely here to fully here at the Schwinger limit energy densities. Of course the only way to prove this QV conjecture is to test a given frustum design over a broad input power range of four orders of magnitude or greater to see if it generates the COMSOL/QV Plasma code's EW copper frustum's TM010 thrust predictions I posted at NSF.com earlier, or not.Best, Paul M.
I have considered the MHD model for many, many years. My conclusion has been that, the temperature at which electron-positron pairs annihilate each other is in excess of 108 Kelvin. If e-p pairs in the frustum had a density ~1x1012 kg/m3, and a life time of ~10-22 s, the frustum would be vaporized from the heat, faster than dropping it onto the surface of the sun.The paper in JBIS is saying that it would require a mass of e-p pairs in excess of 105 kg. So the heat and the mass would not go undetected, therefore that's not it.Regarding the paper you attached, I love this paper! However, at the scale of electrons and quarks, they are constantly undergoing exchange scattering with their counterparts in the QV. At this scale it is possible because the E field exceeds the Schwinger limit, but in the frustum the E field is no where near that limit. So the expectation of producing so many pairs is unreasonable, and I offer that it can't be happening if the frustum is not melting instantly upon their creation.Todd
Quote from: TheTraveller on 11/23/2016 03:52 pmQuote from: RotoSequence on 11/23/2016 03:42 pmTangent to the present discussion, it's curious that the Eagleworks paper shows effectively no linear response in forward thrust between the 60 to 80 watt runs. Thoughts?I believe doing tuning in vac involves a bit of what someone I know once called "Kentucky Windage"?Would suggest the force vs power results could have been tighter if they had the lowest reflected freq tuner instead of the PLL.Phil:"I believe doing tuning in vac involves a bit of what someone I know once called "Kentucky Windage"?"With 20/20 hindsight in place some of us now know that PLL frequency trackers are NOT the best way to go. What is needed is a digital S11 resonant frequency tracker that can accommodate a variable permitivity in the frustum due to pressure changes, but with a force feedback input that can skew the drive frequency off peak resonant power just a few Hz to kHz to maximize the dynamic force output. It also needs to accommodate vehicle acceleration in the manner that Shawyer has talked about in his patents.Best, Paul M.
Quote from: RotoSequence on 11/23/2016 03:42 pmTangent to the present discussion, it's curious that the Eagleworks paper shows effectively no linear response in forward thrust between the 60 to 80 watt runs. Thoughts?I believe doing tuning in vac involves a bit of what someone I know once called "Kentucky Windage"?Would suggest the force vs power results could have been tighter if they had the lowest reflected freq tuner instead of the PLL.
Tangent to the present discussion, it's curious that the Eagleworks paper shows effectively no linear response in forward thrust between the 60 to 80 watt runs. Thoughts?
Hey @rfmwguy,I'm interested in doing spectrum analysis of my magnetrons and was curious of what equipment you used. I remember EW measured the spectrum of leakage from their microwave button panel with a water load inside. Did you do something similar? What kind of analyzer did you use?Thank you
Simple question to the ForumIf you theory guys had a working EmDrive, on a rotary test rig, at your disposal, what would be the process to develop an acceptable theory to explain what you are observing?What data would you need from the test rig?Please try to be specific so I can ensure that data is available.
Quote from: rq3 on 11/23/2016 01:00 amQuote from: Flyby on 11/22/2016 10:50 pm......I'm asking for more insight on the relation between momentum and reflectance, because it would have profound implications :If i may simplify the situation a bit to explain what was perhaps a bit too poorly elaborated :I recall the discussions about the tennis balls bouncing back and forth in a huge frustum space station.As long you consider the reflectance of the walls to be uniform in every direction, it is only the angle of incidence that will determine the size of the momentum. And in the end, when you add up all bounces, the final sum of all forces will be zero. That much I understood...But I see a problem if the reflectance of the walls would vary according the direction you throw the balls. It would mean that for the direction (small end > big end) the transfer of momentum/force would be smaller then what the angle of incidence would predict.So, it puzzles me on how the relation is then, between the reflectance and the momentum transfer ?To put it simply, physics as we know it requires a force to THROW THE BALL! If you're in a funnel shaped copper cavity headed towards the moon, and you throw a tennis ball towards the moon, you and your cavity are accelerated away from the moon due to the energy required to THROW THE BALL. The tennis ball can then hit a steel plate, a mattress, or glance off the walls. It doesn't matter. When all of the energy has dissipated and the ball has come to rest, the net result is zero gain in momentum. At the most basic level, this is the fundamental issue with the Emdrive, and the issue every one here is trying to explain.EDIT: Of course, an Emdrive is constantly stuffing more and more tennis balls into your copper cavity, and insisting that you throw them in a collimated fashion so that as one tennis ball is leaving your hand, the last one you threw is just exactly bouncing off the wall of your choice (hence all of the discussion about modes and Q). The more tennis balls you can deal with, the greater the Q. The end result is the same. You're going nowhere at a great rate, surrounded by tennis balls. Unless, of course, current physics is incomplete. And I'm sure it is Sigh.. I knew this would happen the moment I started writing about tennis balls...I thought it would be more clear the tennis ball analogy is rather flawed, but apparently, it isn't... It is not about the total sum of all the action/reactions I'm writing about, but I'm trying to get the understanding about reflection right.Reflection is the most essential feature/process of what happens inside an EMdrive.If you take 1 complete cycle, going from big end to small en and back, the total sum of the reflectance from small to big end is < then the total sum, especially when you consider it to be a wave, instead of a particle.The problem with particles is that we associate the too much with real life observations where hard kinetic impacts have an apparent linear relation with the angle of incidence.I'm not trying to explain the EMdrive with this, I don't have a comprehensive theory. I only have questions.In this case about reflection and its relation with force/momentum transfer, because it is the most essential part of what happens inside an EMdrive.The non linearity of reflection is really counter-intuitive and understanding it "might" give a clue to why an EMdrive functions. (IF it really functions).My idea is that - IF the EMdrive does indeed work - we need to see and rethink what misconceptions we have, because maybe we then can find clues that help solve these apparent conflicts. The EMdrive (probably) does not violate CoM. The press likes sensation but totally reverses the logic... The question should be : what did we miss in our understanding of CoM, that doesn't need "new physics", but only a more accurate understanding of what's happening...This means retracing, step by step, what we know and investigating any of the shortcuts we took for granted for so long...Because it is a resonance cavity, any minuscule variation can get potentially amplified (Q 100k ? or more) to a point it becomes no longer negligible...So questions like : what brings us the non-linearity of reflection, or the extraordinary momentum/spin in evanescent waves, become important because they're not really considered in our daily understanding of the world around us.As far as comprehensive theories goes, I do have a preference for Todd's asymmetric dissipation/attenuation based upon the wave properties of RF waves...It's way above my head how he does it, but it looks like a logical and elegant solution to the apparent CoM/CoE conflict...
Quote from: Flyby on 11/22/2016 10:50 pm......I'm asking for more insight on the relation between momentum and reflectance, because it would have profound implications :If i may simplify the situation a bit to explain what was perhaps a bit too poorly elaborated :I recall the discussions about the tennis balls bouncing back and forth in a huge frustum space station.As long you consider the reflectance of the walls to be uniform in every direction, it is only the angle of incidence that will determine the size of the momentum. And in the end, when you add up all bounces, the final sum of all forces will be zero. That much I understood...But I see a problem if the reflectance of the walls would vary according the direction you throw the balls. It would mean that for the direction (small end > big end) the transfer of momentum/force would be smaller then what the angle of incidence would predict.So, it puzzles me on how the relation is then, between the reflectance and the momentum transfer ?To put it simply, physics as we know it requires a force to THROW THE BALL! If you're in a funnel shaped copper cavity headed towards the moon, and you throw a tennis ball towards the moon, you and your cavity are accelerated away from the moon due to the energy required to THROW THE BALL. The tennis ball can then hit a steel plate, a mattress, or glance off the walls. It doesn't matter. When all of the energy has dissipated and the ball has come to rest, the net result is zero gain in momentum. At the most basic level, this is the fundamental issue with the Emdrive, and the issue every one here is trying to explain.EDIT: Of course, an Emdrive is constantly stuffing more and more tennis balls into your copper cavity, and insisting that you throw them in a collimated fashion so that as one tennis ball is leaving your hand, the last one you threw is just exactly bouncing off the wall of your choice (hence all of the discussion about modes and Q). The more tennis balls you can deal with, the greater the Q. The end result is the same. You're going nowhere at a great rate, surrounded by tennis balls. Unless, of course, current physics is incomplete. And I'm sure it is
......I'm asking for more insight on the relation between momentum and reflectance, because it would have profound implications :If i may simplify the situation a bit to explain what was perhaps a bit too poorly elaborated :I recall the discussions about the tennis balls bouncing back and forth in a huge frustum space station.As long you consider the reflectance of the walls to be uniform in every direction, it is only the angle of incidence that will determine the size of the momentum. And in the end, when you add up all bounces, the final sum of all forces will be zero. That much I understood...But I see a problem if the reflectance of the walls would vary according the direction you throw the balls. It would mean that for the direction (small end > big end) the transfer of momentum/force would be smaller then what the angle of incidence would predict.So, it puzzles me on how the relation is then, between the reflectance and the momentum transfer ?
TT, re cavity fabrication ..... if memory serves no more than 4/100s margins? yes? thnx , FL
Have you seen this recent interview with Shawyer for IBTimes UK where he claims that he had EmDrives having 8 g and 18 g of thrust (the latter one Boeing has been testing): What do you think?
..."Shouldn't the time process for a degradable Quantum Vacuum be many orders of magnitude faster?"Agreed, but IMO the time delays observed in the fall 2015 EW lab's in-vacuum testing are specific to the ICFTA design interactions with the EW torque pendulum and are not inherent in the degradable QV interactions. The EW lab's Dec 2014 split system in-vacuum test had much more prompt force turn-on and turn-off responses as demonstrated in figure 12 in the AIAA/JPP paper and my spring 2015 postings here a NSF.com. I've attached a couple of slides from this spring 2015 time period as a reminder to all.Best, Paul M.
Quote from: txdrive on 11/21/2016 09:36 pmQuote from: as58 on 11/21/2016 07:57 pmQuote from: txdrive on 11/21/2016 07:41 pmQuoteAs will be discussed in more detail at the end of the section on slope filtering, in order to run the test article in a fully integrated configuration, the torsion pendulum is operated in a highly loaded configuration, which results in slower displacement rates for the torsion pendulum when an impulsive force is applied.Perhaps nudging the pendulum with a known force could let us get a time to use in place of "slower"?If there only were some kind of, I don't know, calibration pulse.In all seriousness... this is pretty bad. I use the calibration pulse to determine the time constant of the pendulum as 4 seconds, and get no thrust in their latest graphs. What ever was responding to power rapidly is now gone.Yes, there's something odd at 17..20 s , but then, there's great many components being heated non-uniformly. Some may even be undergoing quasi-phase changes (plastics have a glass transition temperature). Some may be warping until they mechanically come in contact with another component.All:This will be my last post of the day. The EW Integrated Copper Frustum Test Article (ICFTA) had metallic and plastic components with competing and non-linear thermal expansions and contractions when heated, see previous posted slides on this topic, that when driving the torque pendulum's center of gravity shifts, blurred the impulsive response of this test article in time, dependent on the magnitude of the impulsive force. For me, it is fully explained in the text of the JPP report, so please go back and read it this section again until it hopefully makes sense to you. Best, Paul M.
Quote from: as58 on 11/21/2016 07:57 pmQuote from: txdrive on 11/21/2016 07:41 pmQuoteAs will be discussed in more detail at the end of the section on slope filtering, in order to run the test article in a fully integrated configuration, the torsion pendulum is operated in a highly loaded configuration, which results in slower displacement rates for the torsion pendulum when an impulsive force is applied.Perhaps nudging the pendulum with a known force could let us get a time to use in place of "slower"?If there only were some kind of, I don't know, calibration pulse.In all seriousness... this is pretty bad. I use the calibration pulse to determine the time constant of the pendulum as 4 seconds, and get no thrust in their latest graphs. What ever was responding to power rapidly is now gone.Yes, there's something odd at 17..20 s , but then, there's great many components being heated non-uniformly. Some may even be undergoing quasi-phase changes (plastics have a glass transition temperature). Some may be warping until they mechanically come in contact with another component.
Quote from: txdrive on 11/21/2016 07:41 pmQuoteAs will be discussed in more detail at the end of the section on slope filtering, in order to run the test article in a fully integrated configuration, the torsion pendulum is operated in a highly loaded configuration, which results in slower displacement rates for the torsion pendulum when an impulsive force is applied.Perhaps nudging the pendulum with a known force could let us get a time to use in place of "slower"?If there only were some kind of, I don't know, calibration pulse.
QuoteAs will be discussed in more detail at the end of the section on slope filtering, in order to run the test article in a fully integrated configuration, the torsion pendulum is operated in a highly loaded configuration, which results in slower displacement rates for the torsion pendulum when an impulsive force is applied.Perhaps nudging the pendulum with a known force could let us get a time to use in place of "slower"?
As will be discussed in more detail at the end of the section on slope filtering, in order to run the test article in a fully integrated configuration, the torsion pendulum is operated in a highly loaded configuration, which results in slower displacement rates for the torsion pendulum when an impulsive force is applied.
Perhaps L-3 became aware of the potential fire hazard of igniting a plasma in a high Q cavity with high power microwaves? IIRC, ~100 MW is the max for an outstanding vacuum in accelerator cavities. If the Q is 10K, and you put 10KW in, there's your 100 MW.
Quote from: FattyLumpkin on 11/24/2016 12:23 amTT, re cavity fabrication ..... if memory serves no more than 4/100s margins? yes? thnx , FL What does this mean? What are 4/100 margins? Margins of what? Have you a reference to previous posts? Perhaps keep in mind you appear to be asking questions on a public forum of a member who has accomplished a lot of arm waving, prematurely released results without permission to do so, and otherwise posted nothing but noise, unless it was ideas he's slowly absorbed from other's input on this very site. "Magic Happens Inside" strongly implies that some folks don't really understand how to impliment the hardware they fantasize, yet would like to appear to be able to do so. Claims of fabrication, with ball point pen sketches on napkins of multi-thousand dollar hardware just smells "odd", in my not so humble opinion. If, perchance, you are asking about frustum fabrication tolerances, you might want to include the measurement system involved (English, metric, Klingon). In any case, no published results have determined that fabrication tolerances have any effect whatsoever, except as thay may influence cavity Q, which is well established microwave engineering.As a microwave engineer, please don't get into the "how do I fabricate a cavity to resonate with my crappy source" discussion again. Even the latest NASA paper is past this one. You need to build the highest Q cavity possible, and then tune the driving microwave source to it, with a control loop that optimizes force. I addressed this almost 2 years ago. Since absolutely no one knows whether this effect exists at all, optimizing for reflection coefficient or any other effect other than the desired one (thrust versus input microwave power) is completely pointless. Maximize the effect until it is out of all conceivable noise, and develop the theory once the effect is proven. To date, the effect is polywater. All results are "down in the grass" (the baseline noise you see on a spectrum analyser due to it's own thermal and phase noise signature).