Quote from: TheTraveller on 07/26/2015 09:56 pmAnybody know anything about SuperFish?http://www.lanl.gov/projects/feynman-center/technologies/software/poisson-superfish.phpI know that the official download site is down at the moment. I was able to find a mirror site, so if anyone wants to play around with it, you can use the link:http://hallaweb.jlab.org/12GeV/SoLID/download/field/PoissonSuperfish_7.18.exe
Anybody know anything about SuperFish?http://www.lanl.gov/projects/feynman-center/technologies/software/poisson-superfish.php
Quote from: TheTraveller on 07/26/2015 05:41 pmQuote from: flux_capacitor on 07/26/2015 05:27 pmQuote from: TheTraveller on 07/26/2015 04:09 pmThis short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.Yes but the Chinese used a noisy 1000W magnetron, which has AM and FM modulation over a wider bandwidth than your cleaner solid-state 100W RF amp. I remember Shawyer told you to use a magnetron with flat end plates, but a narrow-band emitter with spherical ends.Correct.But the new build Prof Yang has shared allows using flat end plates to obtain a Q of 117,500 by using short constant diameter set backs as attached. I assume the set backs convert a spherical wavefront into a planar wavefront in both directions.When using a tapered waveguide to connect different diameter cylindrical waveguides this is what happens. Planar going in, spherical inside the tapered section and planar when emerging into the opposite side constant diameter cylindrical section.I see this as a major advancement in EMDrive frustum design.My 1st build has now altered to be able to experiment with this new structure as attached. Double ended tuning with sliding end plates inside constant diameter sections. Shawyer did do this for the small end in his Demonstrator EMDrive and repeated it with the Tajmar EMDrive. Both magnetron driven.If this setup can eliminate the need for spherical end plates and still deliver an unloaded Q of 117,500, bring it on.BTW to those "group velocity is different at each end of the frustum" doubters, wonder what the group velocity will be in those constant diameter sections? Would suggest it will be the group velocity as per the constant diameter circular waveguide equations. Which means Cullen, Shawyer & Prof Yang are correct.This is very interesting. However, something twigged prompting me to realize that we now have a fustrum and two cylinders!! This must introduce some very interesting dynamics to an already complex situation. Evanescent waves must be going crazy in there.Seeing a meep simulation of one of our standard models with these extensions would be very, very illuminating.
Quote from: flux_capacitor on 07/26/2015 05:27 pmQuote from: TheTraveller on 07/26/2015 04:09 pmThis short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.Yes but the Chinese used a noisy 1000W magnetron, which has AM and FM modulation over a wider bandwidth than your cleaner solid-state 100W RF amp. I remember Shawyer told you to use a magnetron with flat end plates, but a narrow-band emitter with spherical ends.Correct.But the new build Prof Yang has shared allows using flat end plates to obtain a Q of 117,500 by using short constant diameter set backs as attached. I assume the set backs convert a spherical wavefront into a planar wavefront in both directions.When using a tapered waveguide to connect different diameter cylindrical waveguides this is what happens. Planar going in, spherical inside the tapered section and planar when emerging into the opposite side constant diameter cylindrical section.I see this as a major advancement in EMDrive frustum design.My 1st build has now altered to be able to experiment with this new structure as attached. Double ended tuning with sliding end plates inside constant diameter sections. Shawyer did do this for the small end in his Demonstrator EMDrive and repeated it with the Tajmar EMDrive. Both magnetron driven.If this setup can eliminate the need for spherical end plates and still deliver an unloaded Q of 117,500, bring it on.BTW to those "group velocity is different at each end of the frustum" doubters, wonder what the group velocity will be in those constant diameter sections? Would suggest it will be the group velocity as per the constant diameter circular waveguide equations. Which means Cullen, Shawyer & Prof Yang are correct.
Quote from: TheTraveller on 07/26/2015 04:09 pmThis short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.Yes but the Chinese used a noisy 1000W magnetron, which has AM and FM modulation over a wider bandwidth than your cleaner solid-state 100W RF amp. I remember Shawyer told you to use a magnetron with flat end plates, but a narrow-band emitter with spherical ends.
This short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.
A post over on reddit attributes the thrust to a phenomenon called sputtering. I was wondering how valid this interpretation is. It appears to depend on oxidation, which seems unlikely in a vacuum. Link:http://www.reddit.com/r/Futurology/comments/3emk49/direct_thrust_measured_from_propellantless_em/cthg9uo
....Also apart from the availability of small microwave magnetrons I don't know why we are looking at 2.45GHz since that is restricting you to small ~10kW power levels. There are no 2.45GHz 100kW magnetrons unfortunately. Highest available frequencies are like 940MHz and 930MHz is easily available. Also need to worry about how the isolator waterload would impact the unit; I would assume that since we are looking for resonance the lost RF wouldn't be a concern.
Quote from: demofsky on 07/27/2015 02:45 amQuote from: TheTraveller on 07/26/2015 05:41 pmQuote from: flux_capacitor on 07/26/2015 05:27 pmQuote from: TheTraveller on 07/26/2015 04:09 pmThis short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.Yes but the Chinese used a noisy 1000W magnetron, which has AM and FM modulation over a wider bandwidth than your cleaner solid-state 100W RF amp. I remember Shawyer told you to use a magnetron with flat end plates, but a narrow-band emitter with spherical ends.Correct.But the new build Prof Yang has shared allows using flat end plates to obtain a Q of 117,500 by using short constant diameter set backs as attached. I assume the set backs convert a spherical wavefront into a planar wavefront in both directions.When using a tapered waveguide to connect different diameter cylindrical waveguides this is what happens. Planar going in, spherical inside the tapered section and planar when emerging into the opposite side constant diameter cylindrical section.I see this as a major advancement in EMDrive frustum design.My 1st build has now altered to be able to experiment with this new structure as attached. Double ended tuning with sliding end plates inside constant diameter sections. Shawyer did do this for the small end in his Demonstrator EMDrive and repeated it with the Tajmar EMDrive. Both magnetron driven.If this setup can eliminate the need for spherical end plates and still deliver an unloaded Q of 117,500, bring it on.BTW to those "group velocity is different at each end of the frustum" doubters, wonder what the group velocity will be in those constant diameter sections? Would suggest it will be the group velocity as per the constant diameter circular waveguide equations. Which means Cullen, Shawyer & Prof Yang are correct.This is very interesting. However, something twigged prompting me to realize that we now have a fustrum and two cylinders!! This must introduce some very interesting dynamics to an already complex situation. Evanescent waves must be going crazy in there.Seeing a meep simulation of one of our standard models with these extensions would be very, very illuminating.The Tagmar setup is a bit different than this setup in that it looked like the Magnetron was mounted on the broadside of the waveguide, probably a E-probe 1/4 Lambda from the endwall,which will launch a TE mode that is coupled to the resonant iris which then reflected a matched source to the frustum sidewall which should then excite a TM mode in the frustum transverse axis which is at approx a right angle to rectangular waveguide. The diagram which shows a similar setup with the E-probe in the rectangular wave guide end wall will launch a TM mode which will be matched by the iris and reflect a matched source to the frustum wall but should excite a TE mode in the frustum. It will interesting to see his mode data.
Quote from: CraigPichach on 07/27/2015 05:20 am....Also apart from the availability of small microwave magnetrons I don't know why we are looking at 2.45GHz since that is restricting you to small ~10kW power levels. There are no 2.45GHz 100kW magnetrons unfortunately. Highest available frequencies are like 940MHz and 930MHz is easily available. Also need to worry about how the isolator waterload would impact the unit; I would assume that since we are looking for resonance the lost RF wouldn't be a concern.This has been discussed in the past. The actual magnetrons are fairly inexpensive. However, any fustrum would have to be water cooled along with the magnetron Look at all the handwringing over the impact of the wiring in Tajmar's experiment. Imagine what would be required for water cooling plumbing at the 100kW levels!On the whole it was felt that the engineering was significant and that good work could be done with an oven magnetron before moving on to higher levels after there is consensus on how to design and tune a fustrum.
I'm sure the team at SPR and Prof Yangs team could design and build a 100kW EMDrive. Give me 1 year and I could do it.With 20 of those the IXS Clarke could be built.
The device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al. It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...
Another question for Tajmar is whether they used flat or spherical end plates. The following picture seems to show a spherical end plate.
Quote from: lmbfan on 07/27/2015 05:05 amA post over on reddit attributes the thrust to a phenomenon called sputtering. I was wondering how valid this interpretation is. It appears to depend on oxidation, which seems unlikely in a vacuum. Link:http://www.reddit.com/r/Futurology/comments/3emk49/direct_thrust_measured_from_propellantless_em/cthg9uoThe Tajmar cavity was sealed. The oxidation INSIDE the cavity was what happens to copper as you heat it in a oxygen atmo. Is why my cavity will be sealed and N2 filled at 1/2 atmo pressure.As for his other statements, he needs to reread the paper.
Quote from: lmbfan on 07/27/2015 05:05 amA post over on reddit attributes the thrust to a phenomenon called sputtering. I was wondering how valid this interpretation is. It appears to depend on oxidation, which seems unlikely in a vacuum. Link:http://www.reddit.com/r/Futurology/comments/3emk49/direct_thrust_measured_from_propellantless_em/cthg9uoYou can answer that question by filling the enclosed Frustum with Sulfur hexafluoride,Sulfur hexafluoride is an inorganic, colorless, odorless, non-flammable, extremely potent greenhouse gas which is an excellent electrical insulator. SF 6 has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. But it is hard to keep in a perforated cavity. It is used in high power systems to prevent arcing.Shell