Struck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.
(There are three ~1.00" 1/4-20 nylon bolts mounted on a ~2.00" radius spaced every 120 degrees that hold the first PE disc to the PCB end cap. There is then a layer of 3/4" wide office scotch tape at the interface between the first and second PE discs and the center 1/4"-20 nylon bolt that hold second PE disc to the first PE disc.)
it looks like there is a high E-field volume where this center nylon bolt hangs out while running in the TM212 resonant mode.
we tested the copper frustum in its TM010 mode and mounted a 5.0 inch OD by 1.0" thick PTFE disk at the center of the large OD end cap of the copper frustum with one 1/4-20 nylon bolt.
Quote from: Mulletron on 03/24/2015 04:06 pmStruck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.Congratulations on your build progress!As for the HDPE mounting solution...If the initial intention is to replicate the Eagleworks' configuration, I'd propose mimicking the Eagleworks' mounting technique. I've seen at least two different bolt hole patterns in posted images, and some of the verbiage suggesting that different bolt hole patterns are best for different excited modes. ...
Quote from: Mulletron on 03/24/2015 04:06 pmStruck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.QUESTION 1: Before mounting the discs, could you please run a couple of tests without the HDPE discs?If, so I can send you a post showing the mode shapes at the two frequencies near 2.45 GHz and why .There is a mode shape at 2.49 GHz (or at 2.46 GHz according to NASA's COMSOL calculations) that should produce no force without the dielectric disc (because the Poynting vector practically cancels out)There is a mode shape at 2.46 GHz (or at 2.41 GHz according to NASA's COMSOL calculations) that may produce an electromagnetic force without the dielectric disc (because the Poynting vector does not cancel out)QUESTION 2: Do you have access to a thermal IR camera (to identify the mode shapes, etc.) ?
Quote from: Mulletron on 03/24/2015 04:06 pmStruck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.Congratulations on your build progress!As for the HDPE mounting solution...If the initial intention is to replicate the Eagleworks' configuration, I'd propose mimicking the Eagleworks' mounting technique. I've seen at least two different bolt hole patterns in posted images, and some of the verbiage suggesting that different bolt hole patterns are best for different excited modes. (as an aside, since the bolt holes pierce both the dielectric and the copper frustum's plate, I've wondered what the RF field looks like outside of the cavity near those holes; I don't recall seeing any bolt holes in the previously posted/discussed meep sims)
Quote from: jmossman on 03/24/2015 06:53 pmQuote from: Mulletron on 03/24/2015 04:06 pmStruck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.Congratulations on your build progress!As for the HDPE mounting solution...If the initial intention is to replicate the Eagleworks' configuration, I'd propose mimicking the Eagleworks' mounting technique. I've seen at least two different bolt hole patterns in posted images, and some of the verbiage suggesting that different bolt hole patterns are best for different excited modes. (as an aside, since the bolt holes pierce both the dielectric and the copper frustum's plate, I've wondered what the RF field looks like outside of the cavity near those holes; I don't recall seeing any bolt holes in the previously posted/discussed meep sims)My leading intention is to use the 3 Nylon bolt approach like Paul March, but it really pains me to drill holes into perfectly good dielectric resonators. All the Nylon bolts I have at the moment aren't long enough, and if the holes are too big, RF can escape. I'm looking for a better way if there is one.
If your copper in the endplate is thick enough, surface roughening of the copper and of the HD PE results in mechanical interlocking sites and causes bond strength to increase dramatically.
My leading intention is to use the 3 Nylon bolt approach like Paul March, but it really pains me to drill holes into perfectly good dielectric resonators. All the Nylon bolts I have at the moment aren't long enough, and if the holes are too big, RF can escape. I'm looking for a better way if there is one.
Quotetried epoxy and superglue bonding the PE and PTFE discs to the frustum end-caps, but these two plastics just happen to be the slickest and hardest plastics to bond to anything else. Drat!The marine adhesive made by 3M (5200 or 5220 fast cure) will stick to anything
tried epoxy and superglue bonding the PE and PTFE discs to the frustum end-caps, but these two plastics just happen to be the slickest and hardest plastics to bond to anything else. Drat!
I don't understand the (analogy ?) in the following statement:Quotethe circulating currents in the bottom plate observe the circulating current in the top plate as circulating in the same direction and so they are attracted to the top plate. However, the top plate may observe the bottom plate having current circulating in the opposite direction and so it is repelled from the bottom plate. The result is a unidirectional force. How are the circulating currents in the bottom plate "observing" the circulating currents in the top plate?The magnetic electromagnetic fields are out of phase (see the plots below). Why would the bottom circulating current "observe" the top one as circulating in the same direction: "in phase"?(Dustinthewind - [bold with my name is me] in other words information only travels at the speed of light or , dx=c*dt. The key to the image attached is:Reference Numeral - Diagram illustrations as shown in FIGS. 1-2:1 - Electromagnetic force2 - Current in upper wire3 - Current in middle wire4 - Current in lower wire5 - Apparent current of the upper wire6 - Apparent current of the middle wire7 - Apparent current of the lower wire8 - Frame one of six9 - Frame two of six10 - frame three of six11 - frame four of six12 - frame five of six13 - frame six of sixThe image only considers parallel wires but the idea could be extended to make the wires equivalent to the circulating currents in the top and bottom plates or maybe the top plate and some distance down the sidewalls.P.S. the diagram considers three wires but the simplest to consider is only two wires. Ignore one color if you like as they are color coded depending on the wire and limit to two wires. In the three wire diagram the top and bottom wires are out of phase 180 degrees so there is no unidirectional force between them. The wires next to each other are only 90 degrees out of phase. In time what happens is the bottom wire observes the current above it as moving in the same direction = attraction. The top wire observes the current below it as moving in the opposite direction = repulsion)And most important, how does this get around the conservation of momentum problem (if one considers the EM Drive as a closed system with no internal sources) ?(Dustinthewind - here is a quote from the other thread, "A scientific paper that clarifies how newtons 3rd law does not apply to the time delay of information and how it can be used for electromagnetic propulsion. It provides a mathematical background for the time delayed magnetic fields but first illustrating how the static equations miss the effect. https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48" it is titled, "Newton's Third Law in the Framework of Special Relativity" ) - Dustinthewind - Please disregard this reference as I was in error in assuming this paper was dealing with two current loops changing in time 90 degrees out of phase.Assuming no internal magnetic sources (no magnetic monopoles) and no internal electric sources, the divergence of Maxwell's stress tensor is zero (due to the lack of internal sources inside the cavity).The derivative with respect to time of Poynting's vector is zero (if the electromagnetic fields are a harmonic function of time). These conditions lead to no electromagnetic force on the center of mass, even when considering a fully general-relativistic formulation of the principle of conservation of energy-momentum (http://en.wikipedia.org/wiki/Electromagnetic_stress%E2%80%93energy_tensor#Conservation_laws ), because the divergence (in 3D+1 spacetime) of the stress–energy tensor is zero under those previously-stated conditions.In order to have a force and acceleration of the EM Drive one needs electromagnetic sources inside the EM Drive cavity (as assumed for example in Brandenburg's equations) and/or the electromagnetic fields to be a nonlinear non-harmonic function of time.(Dustinthewind - It sounds like you have already considered the time dependent interactions from the sound of it so maybe I'm wrong in speculating on the propulsive effect.)
the circulating currents in the bottom plate observe the circulating current in the top plate as circulating in the same direction and so they are attracted to the top plate. However, the top plate may observe the bottom plate having current circulating in the opposite direction and so it is repelled from the bottom plate. The result is a unidirectional force.
Quote from: Rodal on 03/24/2015 07:22 pmIf your copper in the endplate is thick enough, surface roughening of the copper and of the HD PE results in mechanical interlocking sites and causes bond strength to increase dramatically.I asked this before but my question wasn't answered (perhaps it is a stupid question):Wouldn't roughening the copper internal surface of the end plates (to better bond the glue) dramatically reduce the surface reflectivity, hence the Q factor of the cavity?
Quote from: flux_capacitor on 03/24/2015 07:54 pmQuote from: Rodal on 03/24/2015 07:22 pmIf your copper in the endplate is thick enough, surface roughening of the copper and of the HD PE results in mechanical interlocking sites and causes bond strength to increase dramatically.I asked this before but my question wasn't answered (perhaps it is a stupid question):Wouldn't roughening the copper internal surface of the end plates (to better bond the glue) dramatically reduce the surface reflectivity, hence the Q factor of the cavity?Good point, I presume that surface roughness features with height comparable to the penetration length would have a significant effect on the power loss ratio, so I deleted the mention of roughening to improve adhesion.The effect of roughening on polyethylene does not seem to have universal acceptance: Loctite (see report below) states that they did not find a statistical difference when bonding LDPE (they don't say anything about roughening HD PE)That leaves solvent-based primers as a good option to improve adhesion.Look at page 51 of this report from Henkel North America (Loctite): http://www.henkelna.com/us/content_data/237471_LT2197_Plastic_Guide_v6_LR7911911.pdfwhich are specifically recommended for polyethylene (a very hard to bond polymer)(Ethyl Cyanoacrylate) Loctite 401 Prism from Amazon:http://www.amazon.com/Loctite-Instant-Adhesive-Prism-Bottle/dp/B006GOKRSY/ref=pd_sim_sbs_indust_1?ie=UTF8&refRID=14RMFHYMSB2780RR33CYPrimer for Loctite 401 Prism from Amazon:http://www.amazon.com/Loctite-LOC-18396-770-Cyanoacrylate-Adhesive/dp/B001OBQ8VO/ref=sr_1_fkmr0_1?s=hi&ie=UTF8&qid=1427237585&sr=1-1-fkmr0&keywords=Loctite%C2%AE+770%E2%84%A2+Prism%C2%AE+PrimerTHIS GLUE IS STRONG AND FAST ACTING - MAKE SURE TO WEAR GLOVES AND PROTECT YOURSELF
https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48....
....
Most locomotive systems of today are based on open systems. A rocket sheds exhaust gas to propel itself, a speeding bullet generates recoil. A car pushes the road with the same force that is used to accelerate it, the same is true regarding the interaction of a plane with air and of a ship with water. However, the above relativistic considerations suggest’s a new type of motor which is not based on a open system but rather on a closed one....As a final remark we will address the problem of achieving constant force which may be of interest for locomotive applications. A constant force may be achieved by having a direct current in one loop and a current of uniform second derivative on the other. For the choice of values given in table 2 we obtained FT z ∼= 2.74 Newton.Obviously the switching time may represent some difficulty which one may overcome with advanced enough switching technology perhaps using low resistivity superconducting materials. Another possibility for constructing a relativistic motor is using numerous modular solid-state devices each with fast switching and small current such that an appreciable amount of cumulative forcing will result.
Quote from: Star-Drive on 03/22/2015 07:16 pm....The copper frustum thrust reversal due to only its dielectric placement came when I was experimenting with the TM010 mode,...... I think that this mode shape correct designation is TM011 instead of TM010 because:1) There can be no TMmn0 modes for a truncated cone. TMmn0 modes need to have a constant electromagnetic field in the longitudinal direction of the cavity. This is possible for a cylindrical cavity (containing no other dielectrics inside besides the cavity medium) because it has constant geometrical and material properties in the longitudinal direction. But a conical cavity has variable cross-section in the longitudinal direction, therefore the TMnn0 mode is not possible. The first possible mode (if it is not cut-off) is TMmn1. The exact solution for the truncated cone shows this. See for example: http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html :The quantum mode number "p" for a truncated cone is related to k. k cannot be zero for a truncated cone, since k = ω/c for a truncated cone , therefore k = 0 implies zero frequency for a truncated cone. 2) As the attached plot shows, COMSOL's FEA plot shows an electromagnetic field that is not constant in the longitudinal direction, therefore this is not TM010, it looks instead as TM011 upon closer inspection.(Therefore the analyst's designation for TM011 should be changed to TM012 and so forth for TM01p modes)
....The copper frustum thrust reversal due to only its dielectric placement came when I was experimenting with the TM010 mode,...
@frobnicat: please notice this paper, published in The European Physical Journal PlusNovember 2014, 129:240; which was brought up by @dustinthewind:https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48that states:Quote from: Miron Tuval and Asher Yahalom Newton’s Third Law in the Framework of SpecialRelativityMost locomotive systems of today are based on open systems. A rocket sheds exhaust gas to propel itself, a speeding bullet generates recoil. A car pushes the road with the same force that is used to accelerate it, the same is true regarding the interaction of a plane with air and of a ship with water. However, the above relativistic considerations suggest’s a new type of motor which is not based on a open system but rather on a closed one....As a final remark we will address the problem of achieving constant force which may be of interest for locomotive applications. A constant force may be achieved by having a direct current in one loop and a current of uniform second derivative on the other. For the choice of values given in table 2 we obtained FT z ∼= 2.74 Newton.Obviously the switching time may represent some difficulty which one may overcome with advanced enough switching technology perhaps using low resistivity superconducting materials. Another possibility for constructing a relativistic motor is using numerous modular solid-state devices each with fast switching and small current such that an appreciable amount of cumulative forcing will result.The European Physical Journal arose in 1998 as a merger and continuation of the very prestigious journals Zeitschrift für Physik, Journal de Physique, Il Nuovo Cimento, and other journals.The authors are associated with the renowned Isaac Newton Institute for Mathematical Sciences, an international research institute for mathematics and theoretical physics adjoining the Cambridge University Centre for Mathematical Sciences. In 1993 the British mathematician Andrew Wiles announced at the Institute his proof of Fermat's last theorem. Its director as of May 2012 was Cambridge University Professor John Toland (who is famous for formally proving in 1978, Stokes' conjecture on the existence of gravity waves of maximum height on deep water, a previously open problem in mathematical hydrodynamics which dated back to the 19th century).