Folks - this is a contribution to theory, not replication. It demonstrates a solution to Maxwell's equations in a theoretical infinite two-dimensional cavity which describes a net total Lorentz force on the conductors. There are some reasons why this might be an academic curiosity, but it may be of interest....
Quote from: deltaMass on 07/23/2015 02:32 amI'm curious as to why the capable engineers at EagleWorks are finding Q-values around 5,000 to 6,000, and yet around here there's a lot of talk about Q-values ten times higher?Because EW is using real world materials with analog sources, not discretized sources and idealized copper that doesn't seem to heat or suffer significant losses of any sort. Perhaps, just guessing here, perhaps if the node granularity was less than the skin depth of the copper, we could see more realistic skin effects. But its not so we can't.
I'm curious as to why the capable engineers at EagleWorks are finding Q-values around 5,000 to 6,000, and yet around here there's a lot of talk about Q-values ten times higher?
Dr. Rodal -The plane waves off to left and right carry off momentum. The delay causes the conducting barriers to carryan induced current, and they radiate in both directions....
Regarding using wire mesh,A wire mesh waveguide is described in https://www.jlab.org/ir/MITSeries/V9.PDF pg 287 with a loss of .4db/m, compared to (typical?) .02db/m. Only ~10%. However, wouldn't one have to multiply that by the expected number of reverberations the wave will traverse? My math on factorials or series is a bit rusty.$120 for a roll of copper looks pricey compared to the $15 aluminum next to it. Perhaps it can be copper plated? Pretty simple to copper plate.Another paper on how to hack a magnetron, to work as an amplifier, CW and very (relatively) narrow bandwidth, and use magnetic solenoid tuning:http://n5dux.com/ham/files/pdf/The%20Magnetron-A%20Low%20Noise%20Long%20Life%20Amplifier.pdf
Quote from: SeeShells on 07/23/2015 02:18 amQuote from: Rodal on 07/23/2015 12:27 amQuote from: aero on 07/22/2015 11:50 pm...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.I'm looking at the Yang/Shell Axial Antenna at Big Base case now: very unusual: the stress, and hence the force at the small base is practically zero. The stress at the big base is a central point stress from the antenna. Close inspection of this mode looks like another TM11 transverse magnetic mode but with drastically lower amplitude.QUESTION1: was the mesh kept the same as in the previous csv Yang/Shell case, and you are sure this is the stress at the small base and not outside it?Most important: QUESTION2: did Meep give you a Q value for this case ?ThanksHe emailed me saying the Q was something like 57,000+ but was worried about the antenna position, I said run it if you want but I was still doing research into the antenna and had questions out to ppl who had 40 years + in this field. It's not one I would want to make.ShellFriendly reminder that Qs over 10K are probably impractical to consider because of the extremely narrow bandwidth; subject to wide variation of resonant freq caused by thermal/mechanical stresses. You could wind up chasing resonance around, especially with a magnetron. I'm with doc on this, high q is not a prerequisite imho.
Quote from: Rodal on 07/23/2015 12:27 amQuote from: aero on 07/22/2015 11:50 pm...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.I'm looking at the Yang/Shell Axial Antenna at Big Base case now: very unusual: the stress, and hence the force at the small base is practically zero. The stress at the big base is a central point stress from the antenna. Close inspection of this mode looks like another TM11 transverse magnetic mode but with drastically lower amplitude.QUESTION1: was the mesh kept the same as in the previous csv Yang/Shell case, and you are sure this is the stress at the small base and not outside it?Most important: QUESTION2: did Meep give you a Q value for this case ?ThanksHe emailed me saying the Q was something like 57,000+ but was worried about the antenna position, I said run it if you want but I was still doing research into the antenna and had questions out to ppl who had 40 years + in this field. It's not one I would want to make.Shell
Quote from: aero on 07/22/2015 11:50 pm...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.I'm looking at the Yang/Shell Axial Antenna at Big Base case now: very unusual: the stress, and hence the force at the small base is practically zero. The stress at the big base is a central point stress from the antenna. Close inspection of this mode looks like another TM11 transverse magnetic mode but with drastically lower amplitude.QUESTION1: was the mesh kept the same as in the previous csv Yang/Shell case, and you are sure this is the stress at the small base and not outside it?Most important: QUESTION2: did Meep give you a Q value for this case ?Thanks
...I wondered why that went quicker last night. Not quick but a little quicker. I guess you found out. Check it again, they are there now.
I think I've lost track of all the DIYers now. Let's see:1. TheTraveller2. SeeShells3. rfmwguy4. Mulletron (?)5. klm(?)Is this on the wiki?Is the wiki link not supposed to be at the top of the page btw? - can't find it.
Quote from: deltaMass on 07/23/2015 03:25 amI think I've lost track of all the DIYers now. Let's see:1. TheTraveller2. SeeShells3. rfmwguy4. Mulletron (?)5. klm(?)Is this on the wiki?Is the wiki link not supposed to be at the top of the page btw? - can't find it.Concerning, this, what do people think about reporting NULL results of experimenters ? .So far we have put in the wiki the information about the Aachen Baby EM Drive guys results as being Null, as hard as they try they are clearly Null, so far (and they have tried different measurements).However we have not reported as Null the partial results of others (with a question mark on the list). Should we post those partial null results as NULL in the Wiki experimental results table http://emdrive.wiki/Experimental_Results ?
Quote from: deltaMass on 07/23/2015 03:25 amI think I've lost track of all the DIYers now. Let's see:1. TheTraveller2. SeeShells3. rfmwguy4. Mulletron (?)5. klm(?)Is this on the wiki?Is the wiki link not supposed to be at the top of the page btw? - can't find it.Concerning, this, what do people think about reporting NULL results of experimenters ? .So far we have put in the wiki the information about the Aachen Baby EM Drive guys results as being Null, as hard as they try they are clearly Null, so far (and they have tried different measurements).However we have not reported as Null the partial results of others (with a question mark on the list). Should we post those partial null results as NULL in the Wiki experimental results table http://emdrive.wiki/Experimental_Results ?And how should we report the results of rfmwguy and SeeShells and others if they are initially reported as NULL ?Should we put those results as Null in the the wiki or wait some amount of time (what amount of time ? ) until they perform further experiments and analysis ?(and if they are initially positive, do we report them right away as positive or do we wait a period of time ?)
Quote from: mwvp on 07/23/2015 09:42 amRegarding using wire mesh,A wire mesh waveguide is described in https://www.jlab.org/ir/MITSeries/V9.PDF pg 287 with a loss of .4db/m, compared to (typical?) .02db/m. Only ~10%. However, wouldn't one have to multiply that by the expected number of reverberations the wave will traverse? My math on factorials or series is a bit rusty.$120 for a roll of copper looks pricey compared to the $15 aluminum next to it. Perhaps it can be copper plated? Pretty simple to copper plate.Another paper on how to hack a magnetron, to work as an amplifier, CW and very (relatively) narrow bandwidth, and use magnetic solenoid tuning:http://n5dux.com/ham/files/pdf/The%20Magnetron-A%20Low%20Noise%20Long%20Life%20Amplifier.pdfNice links. wire mesh intrigued me for several reasons that Doc has summarized. Another one may be the angle of reflection, or better yet, scattering of radiation. Assuming outward vector forces are striking frustum side walls.
Ignore this if it's already posted, but you may want to have a look at this paper: http://arxiv.org/pdf/1302.2537v1.pdf"Newton’s Third Law in the Framework of Special Relativity"The conclusions are pretty juicy, I quote part of them:"We have shown in this paper that in general Newton’s third law is not compatible with the principles of special relativity and the total force on a two current loop system is not zero"Then discusses how to get constant (reactionless!) force using two wires of conducting material, one with constant direct current and the other carefully modulated, if I understand the paper well enough,.
Quote from: Tron on 07/23/2015 02:05 pmIgnore this if it's already posted, but you may want to have a look at this paper: http://arxiv.org/pdf/1302.2537v1.pdf"Newton’s Third Law in the Framework of Special Relativity"The conclusions are pretty juicy, I quote part of them:"We have shown in this paper that in general Newton’s third law is not compatible with the principles of special relativity and the total force on a two current loop system is not zero"Then discusses how to get constant (reactionless!) force using two wires of conducting material, one with constant direct current and the other carefully modulated, if I understand the paper well enough,.It is just a directional "two loop" antenna. The net force becomes from non isotropic asymmetrical radiaton pattern of the antenna.
This was discussed in thread 2, thing is for a "propulsive effect" of constant thrust it relies on a non stationary ever increasing current :http://forum.nasaspaceflight.com/index.php?topic=36313.msg1350655#msg1350655
I thought I would chime in with questions for the AIAA conference. I am going to be attending the event, so I will be able to report back to you guys about what happens, other questions that were asked, etc. Let me know of a couple of definite questions that anyone would want me to ask during the Q and A, AIAA Propulsion and Energy Forum and ExpositionHilton Orlando, Orlando, Florida...TUESDAY, JULY 28, 2015 NFF-04. Future Flight Propulsion Systems ...5:00 PM - 5:30 PMDirect Thrust Measurements of an EMDrive and Evaluation of Possible Side-Effects Martin Tajmar
Quote from: aero on 07/23/2015 02:42 amBecause EW is using real world materials with analog sources, not discretized sources and idealized copper that doesn't seem to heat or suffer significant losses of any sort. Perhaps, just guessing here, perhaps if the node granularity was less than the skin depth of the copper, we could see more realistic skin effects. But its not so we can't.I'm currently running some tests using MIT's starcluster to automate a cluster of meep servers. Using a higher resolution setting in meep of course is much slower, but I think it may allow for more parallelism. If that proves to be true, higher resolutions could be run at a more feasible speed at the expense of using a more costly cluster of servers. Would that be helpful to you folks?
Because EW is using real world materials with analog sources, not discretized sources and idealized copper that doesn't seem to heat or suffer significant losses of any sort. Perhaps, just guessing here, perhaps if the node granularity was less than the skin depth of the copper, we could see more realistic skin effects. But its not so we can't.