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#80 by SeeShells on 12 Dec, 2015 21:39
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We had some real problems with porosity of multi-layered surfaces when separating the wafers into single dies with our equipment. This is only considering the mechanical stresses and the chipping of the materials from micro-seed fracturing caused by voids in the materials by the sometimes multiple bonding techniques.
I asked the Tech Support on the quality of deposited silver and he assured me it is 99.9% silver. How much silver you lay down is dependent of time plating. With the little wand that comes in the kit it's very slow but you can increase the time by using a SS 3/8" rod and making a bath for your part ~3=4" deep and drop the rod about 2" into the soultion and about 2" up from the bottom.Non cyanide silver plating solutions are fairly toxic so I was thinking that the parts could be fabricated out of fine silver sheet. I looked up todays prices on the Rio Grande site and found that a .010" thick 6" X 24" sheet costs about $130.
Welcome to the forum
Your suggestion would also address the possible problem of porosity leading to lower conductivity (assuming that the silver sheets are fabricated such as resulting in a non-porous sheet)
On the other hand, there maybe a possible problem of waviness/non-flatness of the sheet due to being so thin, as the surface needs to be smooth for reflection purposes.
Dr. Rodal,
If the sliver plating is greater than skin deapth, shouldn't that avoid the problems in the earlier linked article on the affect of plating? It seems the only issue at that point should be the purity of the plating...
I remember you mentioned this earlier and now I will do the forbidden and assume...., that when electroplating the silver is laid down as atoms or close to it. Using the stainless steel electrode there would be no possibility of eroding clumps of silver from the electrode. The question would be whether the stainless leaches any iron or ?? into solution. But stainless steel does seem to be one of the suggested materials.
Chapter from a book, on the Internet. (I'm not responsible for the horrible highlighting which does not highlight anything in particular)
http://www.tau.ac.il/~chemlaba/Files/Electrodeposition/13208_08.pdf
It's not a great leap of faith to see where porosity of a electroplated material could effect the electrical properties by increasing porosity and thereby the conductivity or permeability at higher frequencies.
A couple of points in laying down >40um of silver. Most of your defects in materials with porosity occurs at the boundary layers between the two metals. The Cu can have voids and oxidation, contaminates that are not removed in the pre-process or from simple grubby fingers touching it. Preparing the surface is critical.
The first .1 to maybe 10um of silver you lay down will contain the most defects from you simply not being in a cleanroom fab to prepare the copper, although after you lay your first layers the voids and holes decrease to a level that should not effect the characteristics of the silver on the final 20um. This is why I wanted to at least lay down >40um of silver to build out of that area of first bond.
Now any RF actions will be under 5um and not effected by the first bond of silver onto the copper.
That said it will be interesting when we nail down meep to compare let's say Q in the real world to what meep says and how close the two are.
Just my 2 cents and back to getting some more work done.
Shell
Added: on second thought I think a short snowy afternoon nap is in order. -
#81 by TheTraveller on 12 Dec, 2015 22:11
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Update on my latest build.
Cutting copper next week. Using a 1.2kW Panasonic maggie, driven by a modified Panasonic maggie inverter power supply. Will be using a 5kv vac switch to remove filament power once the maggie is generating microwaves. Expect 1st Force measurements early Jan 2016.
Report back then.
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#82 by John J Gallagher on 12 Dec, 2015 22:40
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Fine and sterling silver sheets are available in thicknesses of .010" to .102" The thinner gauges could be bonded to copper with soft solder to enable a more robust build. Prices range depending on the market but are $1.24 per square inch for the .010" material and $10.96 for the .102" The resistivity of fine silver is 1.67 where as the sterling silvers range from 2.0 to 2.5 . These materials are cast and rolled to thickness so I would think that they will exhibit bulk values. Fine silver will stay soft and can be worked using leather hammers and turned hard wood molds so domed sections can be fabricated with relative ease.
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#83 by SeeShells on 12 Dec, 2015 22:57
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Fine and sterling silver sheets are available in thicknesses of .010" to .102" The thinner gauges could be bonded to copper with soft solder to enable a more robust build. Prices range depending on the market but are $1.24 per square inch for the .010" material and $10.96 for the .102" The resistivity of fine silver is 1.67 where as the sterling silvers range from 2.0 to 2.5 . These materials are cast and rolled to thickness so I would think that they will exhibit bulk values. Fine silver will stay soft and can be worked using leather hammers and turned hard wood molds so domed sections can be fabricated with relative ease.
The resistivity of O2 free copper is 1.72 Ohms cm 10-6 (10.371 Ohms cir-mil/ft) are your figures in cm?
This copper is a little tough to work with. .032" or 0.8mm
Shell -
#84 by aero on 13 Dec, 2015 00:37
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Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
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#85 by OnlyMe on 13 Dec, 2015 00:51
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Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
I thought something Dr. Rodal said earlier was that at microwave frequencies there was little difference between silver and copper? -
#86 by Rodal on 13 Dec, 2015 01:00
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Nope, take another gander at http://forum.nasaspaceflight.com/index.php?topic=39004.msg1455988#msg1455988 (pure silver should result in 40% higher Q than pure copper if both are non-porous and free of defects).Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
I thought something Dr. Rodal said earlier was that at microwave frequencies there was little difference between silver and copper?
On the other hand, according to
Radio Frequency Performance of Electro Plated Finishes
A.M. Fowler
Proceedings IREE Australia May 1970
http://k6mhe.com/n7ws/Plating.pdf
, a porous silver coating can give you a much lower Q of only half as much as pure solid copper. (http://forum.nasaspaceflight.com/index.php?topic=39004.msg1456018#msg1456018) -
#87 by OnlyMe on 13 Dec, 2015 01:07
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Nope, take another gander at http://forum.nasaspaceflight.com/index.php?topic=39004.msg1455988#msg1455988 (pure silver should result in 40% higher Q than pure copper if both are non-porous and free of defects).Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
I thought something Dr. Rodal said earlier was that at microwave frequencies there was little difference between silver and copper?
On the other hand, according to
Radio Frequency Performance of Electro Plated Finishes
A.M. Fowler
Proceedings IREE Australia May 1970
http://k6mhe.com/n7ws/Plating.pdf
, a porous silver coating can give you a much lower Q of only half as much as pure solid copper. (http://forum.nasaspaceflight.com/index.php?topic=39004.msg1456018#msg1456018)
Yes, I remember now. Have to think what I was confusing... -
#88 by SeeShells on 13 Dec, 2015 01:08
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If your not sure go with just plain copper and it helps to keep the cost down.
Nope, take another gander at http://forum.nasaspaceflight.com/index.php?topic=39004.msg1455988#msg1455988 (pure silver should result in 40% higher Q than pure copper if both are non-porous and free of defects).Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
I thought something Dr. Rodal said earlier was that at microwave frequencies there was little difference between silver and copper?
On the other hand, according to
Radio Frequency Performance of Electro Plated Finishes
A.M. Fowler
Proceedings IREE Australia May 1970
http://k6mhe.com/n7ws/Plating.pdf
, a porous silver coating can give you a much lower Q of only half as much as pure solid copper. (http://forum.nasaspaceflight.com/index.php?topic=39004.msg1456018#msg1456018)
Next is O2 free copper
Next copper with silver electroplating and can be plain copper.
Next O2 Copper with silver electroplating with gold flash <1um
Next pure silver for a trophy EMDrive.
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#89 by SeeShells on 13 Dec, 2015 01:11
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Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
If you do the silver correctly and avoid the pitfalls of holes and defects you can get up to a 40% boost in just Q. It did cost some but not that much. -
#90 by OnlyMe on 13 Dec, 2015 01:22
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Nope, take another gander at http://forum.nasaspaceflight.com/index.php?topic=39004.msg1455988#msg1455988 (pure silver should result in 40% higher Q than pure copper if both are non-porous and free of defects).Seems to me that if you can get a reproducible signal with silver, you should get one using copper, too. I would think that any more silver will just detract from the effort, and the cost would certainly discourage other DYI'er from entering the fray. I mean, if you use silver and get positive results, everyone will think silver is needed, hence they will be discouraged by the cost.
I thought something Dr. Rodal said earlier was that at microwave frequencies there was little difference between silver and copper?
On the other hand, according to
Radio Frequency Performance of Electro Plated Finishes
A.M. Fowler
Proceedings IREE Australia May 1970
http://k6mhe.com/n7ws/Plating.pdf
, a porous silver coating can give you a much lower Q of only half as much as pure solid copper. (http://forum.nasaspaceflight.com/index.php?topic=39004.msg1456018#msg1456018)
Yes, I remember now. Have to think what I was confusing...
Probably thinking of gold (which is closer to copper in conductivity), just a little lower than pure copper, but gold does not corrode.
I think I was confusing electrical conductivity. -
#91 by SeeShells on 13 Dec, 2015 01:51
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43 years ago I was watching them walk on the moon... for the last time.
I'll never forget them driving around in their very cool looking lunar rover, when that baby pealed out and threw moon dust into the vacuum of space I cheered. I never thought 43 years later we would never be back. It saddened me then and it saddens me now. I always believed we were good enough to go back, claim what was in our neighborhood, our birthright, but we didn't. We should have.
I don't know if this Drive will give us the keys to the neighborhood of space, but it eases the sadness these last 43 years have wrought by me trying and giving what I can to build and test this drive.
Who would have thought a feather of thrust could carry so much weight?
Shell
http://io9.com/the-real-story-of-apollo-17-and-why-we-never-went-ba-1670503448 -
#92 by OnlyMe on 13 Dec, 2015 02:03
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43 years ago I was watching them walk on the moon... for the last time.
I'll never forget them driving around in their very cool looking lunar rover, when that baby pealed out and threw moon dust into the vacuum of space I cheered. I never thought 43 years later we would never be back. It saddened me then and it saddens me now. I always believed we were good enough to go back, claim what was in our neighborhood, our birthright, but we didn't. We should have.
I don't know if this Drive will give us the keys to the neighborhood of space, but it eases the sadness these last 43 years have wrought by me trying and giving what I can to build and test this drive.
Who would have thought a feather of thrust could carry so much weight?
Shell
http://io9.com/the-real-story-of-apollo-17-and-why-we-never-went-ba-1670503448
You know I don't remember the last trip, but I do remember that first step. All gathered around round the TV and the excitement when.., and then my grandfather who had seen gunfights in the streets of Saint Louis broke in to tell us all it was just a Hollywood movie. He never did believe it. And I'll never forget...
How big a the feather?
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#93 by SteveD on 13 Dec, 2015 05:27
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Whatever is going on with the EMDrive, it seems far more likely that the dynamics of the boundary conditions inside the drive, together with an asymmetry in the microwave field density, leads to a asymmetry in the transfer of momentum between the microwaves and the frustum. The issue of relativistic velocities from a constant classical thrust resulting in free energy, is a special relativity problem that should wait until we have some proof that relativistic velocities are even possible.
Personally, I've just been looking at what little data we have and been trying to use it to assign a ballpark probability of how this thing works at a pseudocode level (which risks ending up in pseudoscience pretty quickly). My take is that the drive is a speaker in space. The rf is generating some kind of spacetime wave that has a frequency and can be doppler shifted. The answer to the question of how does a spaceship powered by an EMDrive slow down is the same as how does a photon rocket slow down.
That would explain why the dielectric experiments report so much less thrust. If you have two dielectric disks and a endplate you've got three surfaces that are producing these waves. The waves are interfering with each other, killing the thrust generation. Need to look more at Woodwards work. Wonder if he might be basically right on theory, but having the thrust in his tests killed due to construction issues. (I suppose the next crackpot question is -- if these doppler shifted waves exist -- can they be used to build an Alcubierre Drive). -
#94 by SteveD on 13 Dec, 2015 05:39
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Non cyanide silver plating solutions are fairly toxic so I was thinking that the parts could be fabricated out of fine silver sheet. I looked up todays prices on the Rio Grande site and found that a .010" thick 6" X 24" sheet costs about $130.
That would be one solution for achieving the highest Q possible, but the Fine Silver sheet would have to be mounted on some kind of backing. Alone it would be almost as flimsy as household Aluminum foil.
Hum, posterboard/cardboard with the fine sheet over it for the frustum and the two endplates in a self-supporting configuration of something sturdier based on the NSF-1701 design?
Actually, don't try this with posterboard if it's anything but a very low power solid state design. I worry that it simply won't be ablet to handle the heat involved. -
#95 by SteveD on 13 Dec, 2015 05:41
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I asked the Tech Support on the quality of deposited silver and he assured me it is 99.9% silver. How much silver you lay down is dependent of time plating. With the little wand that comes in the kit it's very slow but you can increase the time by using a SS 3/8" rod and making a bath for your part ~3=4" deep and drop the rod about 2" into the soultion and about 2" up from the bottom.Non cyanide silver plating solutions are fairly toxic so I was thinking that the parts could be fabricated out of fine silver sheet. I looked up todays prices on the Rio Grande site and found that a .010" thick 6" X 24" sheet costs about $130.
Welcome to the forum
Your suggestion would also address the possible problem of porosity leading to lower conductivity (assuming that the silver sheets are fabricated such as resulting in a non-porous sheet)
On the other hand, there maybe a possible problem of waviness/non-flatness of the sheet due to being so thin, as the surface needs to be smooth for reflection purposes.
Dr. Rodal,
If the sliver plating is greater than skin deapth, shouldn't that avoid the problems in the earlier linked article on the affect of plating? It seems the only issue at that point should be the purity of the plating...
Urm, isn't the question the conductivity of the plating. Would it be possible to grab one of the scraps you practiced on and check the conductivity against a scrap of the raw copper? -
#96 by SteveD on 13 Dec, 2015 06:41
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Update on my latest build.
Cutting copper next week. Using a 1.2kW Panasonic maggie, driven by a modified Panasonic maggie inverter power supply. Will be using a 5kv vac switch to remove filament power once the maggie is generating microwaves. Expect 1st Force measurements early Jan 2016.
Report back then.
Am I reading that right that you are using a magnetron feeding directly from a waveguide on top of the frustum. Not sure you arent' being overly optimistic on your Q.
In any event, here's a spreadsheet that I think might help calculate the thermal lift from the air inside the frustum. While the figures on the bottom, energy to heat the air inside the frustum one degree, are still a work in progress -- if you dump 1200watts in there you've got a good chance that things get hot as hell.
BTW welcome back.
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#97 by TheTraveller on 13 Dec, 2015 08:09
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Update on my latest build.
Cutting copper next week. Using a 1.2kW Panasonic maggie, driven by a modified Panasonic maggie inverter power supply. Will be using a 5kv vac switch to remove filament power once the maggie is generating microwaves. Expect 1st Force measurements early Jan 2016.
Report back then.
Am I reading that right that you are using a magnetron feeding directly from a waveguide on top of the frustum. Not sure you arent' being overly optimistic on your Q.
In any event, here's a spreadsheet that I think might help calculate the thermal lift from the air inside the frustum. While the figures on the bottom, energy to heat the air inside the frustum one degree, are still a work in progress -- if you dump 1200watts in there you've got a good chance that things get hot as hell.
BTW welcome back.
Thanks for the feedback. Will have a look at it.
No waveguide used.
Magnetron bolts directly to big end plate launcher with the antenna inside the frustum at the centre of the big end plate to excite TM113 mode. Mounts like Dave's magneton in NSF-1701 as attached.
Magnetron output power is adjustable from around 100W to 1,200W as the full wave voltage doubler inverter power supply control circuits adjust and regulate magnetron current to be constant. This also helps to reduce maggie freq splatter below that measured with simple 1/2 wave voltage doubler power supplies.
Once my spectrum scanner arrives, will be able to measure the freq splatter width generated by both types of maggie & power supplies.
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#98 by SeeShells on 13 Dec, 2015 12:41
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How big a the feather?43 years ago I was watching them walk on the moon... for the last time.
I'll never forget them driving around in their very cool looking lunar rover, when that baby pealed out and threw moon dust into the vacuum of space I cheered. I never thought 43 years later we would never be back. It saddened me then and it saddens me now. I always believed we were good enough to go back, claim what was in our neighborhood, our birthright, but we didn't. We should have.
I don't know if this Drive will give us the keys to the neighborhood of space, but it eases the sadness these last 43 years have wrought by me trying and giving what I can to build and test this drive.
Who would have thought a feather of thrust could carry so much weight?
Shell
http://io9.com/the-real-story-of-apollo-17-and-why-we-never-went-ba-1670503448
You know I don't remember the last trip, but I do remember that first step. All gathered around round the TV and the excitement when.., and then my grandfather who had seen gunfights in the streets of Saint Louis broke in to tell us all it was just a Hollywood movie. He never did believe it. And I'll never forget...
How big a the feather?
Depends on if it's in a vacuum or air, doesn't it? Not ready yet Doc.
Shell -
#99 by Rodal on 13 Dec, 2015 15:29
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Update on my latest build.
Cutting copper next week. Using a 1.2kW Panasonic maggie, driven by a modified Panasonic maggie inverter power supply. Will be using a 5kv vac switch to remove filament power once the maggie is generating microwaves. Expect 1st Force measurements early Jan 2016.
Report back then.
Am I reading that right that you are using a magnetron feeding directly from a waveguide on top of the frustum. Not sure you arent' being overly optimistic on your Q.
In any event, here's a spreadsheet that I think might help calculate the thermal lift from the air inside the frustum. While the figures on the bottom, energy to heat the air inside the frustum one degree, are still a work in progress -- if you dump 1200watts in there you've got a good chance that things get hot as hell.
BTW welcome back.
Thanks for the feedback. Will have a look at it.
No waveguide used.
Magnetron bolts directly to big end plate launcher with the antenna inside the frustum at the centre of the big end plate to excite TM113 mode. Mounts like Dave's magneton in NSF-1701 as attached.
Magnetron output power is adjustable from around 100W to 1,200W as the full wave voltage doubler inverter power supply control circuits adjust and regulate magnetron current to be constant. This also helps to reduce maggie freq splatter below that measured with simple 1/2 wave voltage doubler power supplies.
Once my spectrum scanner arrives, will be able to measure the freq splatter width generated by both types of maggie & power supplies.
On your post http://forum.nasaspaceflight.com/index.php?topic=39004.msg1456624#msg1456624 you state that the Magnetron will excite a transverse MAGNETIC CYLINDRICAL cavity mode TM113
<<Magnetron bolts directly to big end plate launcher with the antenna inside the frustum at the centre of the big end plate to excite TM113 mode>>
while the image for your post http://forum.nasaspaceflight.com/index.php?topic=39004.msg1456505#msg1456505
states that the Magnetron will excite resonance via a transverse ELECTRIC CYLINDRICAL cavity mode TE013
Completely different modes, and the fact is that the cavity in your proposed experiment is NOT a cylindrical cavity, but it is a frustum of a cone, a truncated cone, excited by a magnetron. A Magnetron can excite modes in a truncated cone that have no equivalence in a cylindrical cavity. Many of the Meep runs discussed in these threads show modes that are asymmetric and have no equivalence in cylindrical cavities. (Your spreadsheet cannot excite such asymmetric modes that do not exist in cylindrical cavities so your spreadsheet will be unable to predict whether such an asymmetric mode will be excited in the actual experiment.)
We look forward to discussion of actual experimental data to determine what actual mode shape will be excited. Looking forward to actual experimental verification of the mode shape (using a thermal camera as done by NASA).
__________________________
(*) Neither Yang nor Shawyer have ever published actual experimental data (with a thermal camera) proving what actual mode shapes were excited in their experiments. NASA verified their mode shape in one of their experiments, as per Paul March discussion in previous threads. More experimental data is needed that verifies actual mode shapes excited in EM Drive experiments, to understand what is going on in these experiments.
