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#3940 by Monomorphic on 18 Jul, 2016 15:12
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Dave, just to be clear, our designs are not supposed to arc, yes? What caused the arcing in your build?
Designs should not arc. Imperfections in the copper, silver solder, seams, gaps, etc can cause it. I never heard these arcs forming, especially with the latest mag I have. I tend to think these occurred weeks ago with a previous mag. Spinning copper which would produce no seam on the small diameter would be best...just too expensive to contract this out.
Dave, did you seal your copper with silicone spray? -
#3941 by SeeShells on 18 Jul, 2016 15:28
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Dave, just to be clear, our designs are not supposed to arc, yes? What caused the arcing in your build?
Designs should not arc. Imperfections in the copper, silver solder, seams, gaps, etc can cause it. I never heard these arcs forming, especially with the latest mag I have. I tend to think these occurred weeks ago with a previous mag. Spinning copper which would produce no seam on the small diameter would be best...just too expensive to contract this out.
Dave, did you seal your copper with silicone spray?
Very true. You can passivate the copper from oxidizing by coating the surfaces by using a MG 422B silicone conformal coating spray. It cures @ 150F in an hour. It's well worth the couple bucks.
https://www.amazon.com/MG-Chemicals-Silicone-Conformal-Coating/dp/B008O9YGQI
Shell
made a booboo... fixed it. -
#3942 by rfmwguy on 18 Jul, 2016 16:01
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No, could you get me a pic of the stuff you used?Dave, just to be clear, our designs are not supposed to arc, yes? What caused the arcing in your build?
Designs should not arc. Imperfections in the copper, silver solder, seams, gaps, etc can cause it. I never heard these arcs forming, especially with the latest mag I have. I tend to think these occurred weeks ago with a previous mag. Spinning copper which would produce no seam on the small diameter would be best...just too expensive to contract this out.
Dave, did you seal your copper with silicone spray? -
#3943 by rfmwguy on 18 Jul, 2016 16:06
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Accepting ideas for reconditioning cavity: removing oxidation, smoothing surfaces internally. Cavity cannot be disassembled. My thought was a tumbler or shake table. Anyone with experience with this and the material to use? I'm assuming coarse sand is a no-no.
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#3944 by mikegem on 18 Jul, 2016 16:17
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First 1701A Internal Cavity inspection after weeks of testing:
Overlaying B&W Thermal of small endplate (thanks to Monomorphic) with pic I took today of internal cavity showing arcs. Horizontally flipped internal image so it would match with B&W thermal underneath.
Good correlation between arc spots and heating.
FWIW on arcing in microwave components...
I built CVD chambers at 2.45GHz and 915MHz that ran at 6kW and 60kW respectively. I made prototype chambers by bolting together thick machined plates of aluminum with copper plating on the microwave exposed surfaces. The joined plates fit very well and external detectors showed no radiation leakage.
Nevertheless, I had lots of arcing at the plate joints. I tried a bunch of suppression methods. The only one that reliably worked (and then only temporarily) was to paint each joint on the inside of the chambers with silver paint. Fine while the paint was runny, no arcing. When the paint dried, arcs returned.
After much wondering, I decided it was because as good as the fit was, it wasn't perfect, and there were small spaces where the bolted plates joined. Skin effect made it possible for microwave energy to propagate into these spaces. If the length of these slots was just exactly wrong, the total path length would approximate a quarter wave, leaving one face of the slot at the entrance at a few kV potential with respect to the other. Voila, a high energy arc.
What finally eliminated the arcing was to have the chambers machined from single billets of aluminum. No joints, no arcs. Also a big drain on the project budget. The chambers had removable lids, and there I used machined features that acted as half wave chokes to keep microwave energy away from O-ring seals. No arcs because no potential difference between half wave nodes.
In the frustum you've built - if the arcs are occurring at joined regions, you might use a low melting solder to fill in the joints after you've torqued the bolts. That would fill any residual joint spaces and make them electrically invisible. It also would make disassembly a pain, but not impossible.
Finally, I've also had arcing happen in completely continuous components (extruded waveguide) under really bad VSWR conditions. A TE10 mode arc nearly melted through a silver-plated brass precision waveguide before I shut the source off. So high VSWR, which you might have during mode transitions, could also initiate arcs. -
#3945 by Monomorphic on 18 Jul, 2016 16:21
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No, could you get me a pic of the stuff you used?Dave, just to be clear, our designs are not supposed to arc, yes? What caused the arcing in your build?
Designs should not arc. Imperfections in the copper, silver solder, seams, gaps, etc can cause it. I never heard these arcs forming, especially with the latest mag I have. I tend to think these occurred weeks ago with a previous mag. Spinning copper which would produce no seam on the small diameter would be best...just too expensive to contract this out.
Dave, did you seal your copper with silicone spray?
This is what I used. Believe Shell recommended it. https://www.amazon.com/MG-Chemicals-Silicone-Conformal-Coating/dp/B008O9YGQI/ref=pd_nav_hcs_bia_t_1?ie=UTF8&psc=1&refRID=PXAXSRTK2HQ7JNR97X63 -
#3946 by rfmwguy on 18 Jul, 2016 16:57
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Great info, especially based on your hands-on experience. The Silver Solder in the seams is definitely a weak spot at modal points, which this TM013 is smack dab on the small end. I'll try the silicone spray my builder friends recommend. First, I'll fill the cavity with a fine abrasive, removing all oxidation...perhaps with a shake-table type setup. Once the burn spots are removed, I'll experiment with your suggestion. Only problem I have is the assembly is soldered and epoxied so opening is destroying pretty much.First 1701A Internal Cavity inspection after weeks of testing:
Overlaying B&W Thermal of small endplate (thanks to Monomorphic) with pic I took today of internal cavity showing arcs. Horizontally flipped internal image so it would match with B&W thermal underneath.
Good correlation between arc spots and heating.
FWIW on arcing in microwave components...
I built CVD chambers at 2.45GHz and 915MHz that ran at 6kW and 60kW respectively. I made prototype chambers by bolting together thick machined plates of aluminum with copper plating on the microwave exposed surfaces. The joined plates fit very well and external detectors showed no radiation leakage.
Nevertheless, I had lots of arcing at the plate joints. I tried a bunch of suppression methods. The only one that reliably worked (and then only temporarily) was to paint each joint on the inside of the chambers with silver paint. Fine while the paint was runny, no arcing. When the paint dried, arcs returned.
After much wondering, I decided it was because as good as the fit was, it wasn't perfect, and there were small spaces where the bolted plates joined. Skin effect made it possible for microwave energy to propagate into these spaces. If the length of these slots was just exactly wrong, the total path length would approximate a quarter wave, leaving one face of the slot at the entrance at a few kV potential with respect to the other. Voila, a high energy arc.
What finally eliminated the arcing was to have the chambers machined from single billets of aluminum. No joints, no arcs. Also a big drain on the project budget. The chambers had removable lids, and there I used machined features that acted as half wave chokes to keep microwave energy away from O-ring seals. No arcs because no potential difference between half wave nodes.
In the frustum you've built - if the arcs are occurring at joined regions, you might use a low melting solder to fill in the joints after you've torqued the bolts. That would fill any residual joint spaces and make them electrically invisible. It also would make disassembly a pain, but not impossible.
Finally, I've also had arcing happen in completely continuous components (extruded waveguide) under really bad VSWR conditions. A TE10 mode arc nearly melted through a silver-plated brass precision waveguide before I shut the source off. So high VSWR, which you might have during mode transitions, could also initiate arcs.
Will try to keep everyone posted. -
#3947 by zen-in on 18 Jul, 2016 17:32
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Accepting ideas for reconditioning cavity: removing oxidation, smoothing surfaces internally. Cavity cannot be disassembled. My thought was a tumbler or shake table. Anyone with experience with this and the material to use? I'm assuming coarse sand is a no-no.
Rinse it with dilute sulphuric acid H2SO4, heating the outside of the cone to a low temp with a hair dryer while swirling it around. Rinse with distilled water and drain it. You may have to bake it at low temp to get all the water out. That will dissolve any CuO, leaving the inside pink. If you can train gerbils to polish the inside you have it made. I don't believe that is necessary (the polishing). -
#3948 by rfmwguy on 18 Jul, 2016 17:40
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Thanks, I ordered up some silicon carbide grit (medium) and do a vibratory tumble/shake and see what happens. Gerbils are out...wife has too many cat roaming aboutAccepting ideas for reconditioning cavity: removing oxidation, smoothing surfaces internally. Cavity cannot be disassembled. My thought was a tumbler or shake table. Anyone with experience with this and the material to use? I'm assuming coarse sand is a no-no.
Rinse it with dilute sulphuric acid H2SO4, heating the outside of the cone to a low temp with a hair dryer while swirling it around. Rinse with distilled water and drain it. You may have to bake it at low temp to get all the water out. That will dissolve any CuO, leaving the inside pink. If you can train gerbils to polish the inside you have it made. I don't that is necessary.
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#3949 by Rodal on 18 Jul, 2016 18:44
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...
It's already been shown here, probably back in thread 3 or 4, that the amount of energy density is not nearly enough to have any actual effect on space-time or the vacuum, and the electric fields generated are not high enough to create electron-positron pair creation, or dielectric breakdown of the vacuum as I like to think of it.
I suggest you both look at what is happening within the copper itself, instead of the vacuum. Per my new paper, gravity is a dissipative effect acting on oscillations within matter.
...
Todd
Also look at what is happening within the HDPE polymer insert, and compare with what may be happening in the copper... (hint: there is much more dissipation occurring within the HDPE polymer insert).
The HDPE creates much more asymmetry, particularly for a TM mode (that has an electric field in the longitudinal direction). -
#3950 by JaimeZX on 18 Jul, 2016 21:00
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COINCIDENCE???
First 1701A Internal Cavity inspection after weeks of testing:
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#3951 by RERT on 18 Jul, 2016 21:27
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Hi. I was chatting with my son today about the EM-Drive test rigs. One comment was 'Can they use a strain gauge?'. Sure enough 5 minutes with Google comes up with the Novatech Model 329, a strain gauge with 100milli-Newton range and 4 micronewton max resolution, which is bang in range. I've no idea about anything DIY practical, nor the price of this thing. Thought it worth mentioning that such a thing existed, just in case.
R. -
#3952 by Monomorphic on 18 Jul, 2016 23:32
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Spent a better part of the day completely disassembling the wedge so that I could add a nice polish to the interior. Want to see how this affects Q-factor. This scuffed up the outside, so I added another coat of paint. Waiting for that to dry so I can do another vector network analysis. Here are some before and after shots.
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#3953 by Monomorphic on 19 Jul, 2016 01:05
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Return loss now at -29.29dB. Measured Q-factor using -3dB method: 7,759
Polishing definitely helps! -
#3954 by WarpTech on 19 Jul, 2016 02:09
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Return loss now at -29.29dB. Measured Q-factor using -3dB method: 7,759
Polishing definitely helps!
Give it a push!
Can you monitor the resonant frequency and Q, while giving it a little push forward? Then repeat pushing it backwards?
The concept that the frequency shifts and results in acceleration can be tested the other way around. If accelerating the frustum by exerting a known force causes the frequency to shift and/or the Q to change, it gives us something to characterize what happens when it actually "works". Shawyer said it "ratchets", and this should be observable as a shift in the frequency when you push it. It should shift "lower" if you push the big end, small end leading. It should shift "higher" if you push the small end, big end leading. Thereby requiring more force to push backwards than forwards.
The goal would be to completely characterize what happens to the resonance when the frustum accelerates.
1. Which direction does the frequency shift, depending on which direction you push it?
2. How much does the frequency shift for a given applied force, in each direction?
3. How does this affect the Q?
4. Does the change in Q depend on which way you push it?
etc...
Whatever we learn would be great. Like Shells says, there is no bad data.
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#3955 by SeeShells on 19 Jul, 2016 03:12
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Spent a better part of the day completely disassembling the wedge so that I could add a nice polish to the interior. Want to see how this affects Q-factor. This scuffed up the outside, so I added another coat of paint. Waiting for that to dry so I can do another vector network analysis. Here are some before and after shots.
I'd recommend only one thing on this, otherwise it's great work!
The screw and exposed heads that you used to secure the magnetron waveguide to the drive body may cause you issues from arcing. I found that out on one of the builds and I replaced the screws with brass flat headed screws sometimes called Elevator screws.
https://www.amazon.com/Angelakerry-Browne-Chicago-Button-Leather/dp/B0125X1RKG/ref=sr_1_2?ie=UTF8&qid=1468896060&sr=8-2&keywords=Sam+Browne+Stud+Screw
YMMV
Shell
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#3956 by FattyLumpkin on 19 Jul, 2016 04:04
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Still not quite clear about how folks are estimating Q: My scaled down frustum has a Q of +/- 19,000 mode TE012 @ 2.450161 GHz. Dimensions SD = 12.183 cm, L = 17.544 cm and LD = 21.443 cm. This is indeed quite small when compared to Monomophics's wedge and TM311 frustum. Is this because of the different mode/frequency being stimulated? Or? With bigger cavity shouldn't Q increase? Thanks for the help. , FL
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#3957 by rfmwguy on 19 Jul, 2016 11:02
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"Organisms might be quantum machines"
Think were seeing fresh outlooks on physics. Nice article, thanks. Perhaps unconventional views of physics are being encouraged more than classical beliefs. Makes for a more interesting forum discussion anyway.
http://www.bbc.com/earth/story/20160715-organisms-might-be-quantum-machines
A lot of talk about quantum space and photons here lately. Maybe that article can help give some ideas here too. -
#3958 by Monomorphic on 19 Jul, 2016 13:22
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The screw and exposed heads that you used to secure the magnetron waveguide to the drive body may cause you issues from arcing. I found that out on one of the builds and I replaced the screws with brass flat headed screws sometimes called Elevator screws.
Good advice. I had some thoughts about this as well. What i'm going to do is grind the brass ones I have down to a flat head, sand them smooth, and then reattach them. -
#3959 by SeeShells on 19 Jul, 2016 16:28
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YEA!!!
Got my new matched set of transformers. Been on hold as I lost one of my other ones.
Now I need to wire them in and test.
Shell
