NewSpace 2010: Polywell and Vasimr

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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GIThruster
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Post by GIThruster »

Dave, the "economic" argument for rail guns, launch loops, lightcraft, elevators--are all the same. They all promise they can lower launch costs IF there are enough launches. From your link:

A space elevator built according to the Edwards proposal is estimated to cost $20 billion ($40B with a 100% contingency).[12]

Which everyone knows means if we get the tech, then maybe $100 billion.

Doesn't matter. We don't have $10 billion to spend.

For a golden age of space travel, private industry needs to get involved and make it pay for itself, which means even $1 billion is out of the question.

Honestly, if you had $1 billion to spend, wouldn't you build a TRITON and a bunch of interplanetary cruisers that can not only fly all over our planetary system, land the entire craft on places like Mars and Titan, lift off without leaving bits behind and fly back to LEO? But notice despite how nice that is, it cannot lead to a "Golden Age" of space travel because it cannot pay for itself. NASA could do that to send a few sets of boots all around our system, and I'm wholly in support of such a thing, but this can never lead to a Golden Age of space travel.

Notice, I am not making an argument against each of these macro-engineering schemes. I'm just saying that they're nothing new and will never be built because they cost too much.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

AcesHigh
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Joined: Wed Mar 25, 2009 3:59 am

Post by AcesHigh »

MSimon wrote:
The ridiculous part is someone who defends a system which 99% of the physics community considers as pseudo-science
Chapter 28 of Book 2 of The Feynman Lectures on Physics.
Unexplored science is a better term. The general mass of physicists are a singularly incurious lot.
thats not the point. I agree too many of the physics community are too close minded and just wont accept theories that THEY view as being radical or breaking current laws (they may not break current laws, but there is a long way to explain that to them)

the point is that I dont accept people to tell me to keep an open mind about ME-Effect... an open mind that MANY in the physics community will NOT keep in respect to ME-Effect, and at the same time, the same people have a close mind towards Space Elevators.


UNLESS propellantless thrusters are real and are invented soon, space elevators might VERY WELL have an important part to play in humanity´s near (50-200 years) future.

AcesHigh
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Post by AcesHigh »

GIThruster wrote:We can't even get a billion dollars to develop TRITON. What makes you think we'll ever get hundreds of billions to launch high tech rope into the sky?
the fact that it WONT cost hundreds of billions of dollars? It wont cost even 10 billion?

its not about the private industry not putting 1 billion dollars in a project. Its about the private industry not seeing benefits in putting 1 billion dollars in a project.

if the space elevator develops in the next decades and the concept proves to be viable AND very cheap, that WILL create an industry and 1 billion dollars will be NOTHING if there will be return.

same thing with ME Thrusters. If they are developed, the industry will pour so much money into it that it will make you "hundreds of billions" you talk about space elevators seem like child´s play.



so dont be so negative about the space elevator yet. Keep your negativity towards SE when ME Thrusters are proved beyond any doubt. While that doesnt happen, keep an open mind about the SE concept. There are lots of credible people that consider them to be viable in the next decades.

GIThruster
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Post by GIThruster »

Aces, trust me; I'm entitled to my opinion and you don't get to dictate it to me.

IMHO, space elevators will NEVER happen just as rail guns proposed 40 years ago for launching into orbit did not happen. Why? Because it costs too much.

Got nothing at all to do with M-E tech. Nothing.

Keep in mind we could have gone to Mars 30 years ago. We didn't because people won't spend the money.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Giorgio
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Post by Giorgio »

The issue is not really that it costs too much, but that there is no immediate return for that investment.

If there was a suitable economic reason to go there be sure that we would have already some colonies on the moon and Mars.
Just look back at what happened with the discovery of America.

IntLibber
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Joined: Wed Sep 24, 2008 3:28 pm

Post by IntLibber »

TallDave wrote:Well, NASA's still holding contests and giving awards for SE tech, so they seem to think there may be a path to viability.

Of course, they're probably assuming a fusion-powered rocket is even less likely. The great thing about the future is no one's been there yet.

Here's a nice SE reference: http://www.spaceelevator.com/

On tensile strength:

http://wiki.spaceelevator.com/@api/deki ... dwards.pdf
The primary technical hurdle for construction of
the space elevator is the production of the highstrength
material with a tensile strength of 100
GPa. At the current time, carbon nanotubes
(CNTs) have been measured with tensile
strengths of 200 GPa.
And that was 5 years ago.
That was of the tensile strength of individual molecules, not thread, not rope, not tether. As soon as you start weaving them together, the tensile strength drops rather quickly. That, and the claims of 200GPa are not supportable since nobody has replicated those results.

I think the elevator concept is great for the moon, for Mars, and other small bodies. I don't think we will build one on Earth for at LEAST 50 years or more, and that is with the full expectation that we will see molecular nanotech showing up some time between 2035-2045 on schedule.

This is a chicken and egg economic problem primarily. The engineering problems of building a 30,000 mile long tether that maintains 100GPa along its length, as difficult as that is going to be to achieve, pale in comparison to the economic problem of putting enough mass up into GSO to build the thing in the first place.

Claims it will fit on a Delta IV are utter nonsense and demonstrate the lack of connection to reality that tethernuts have. Maybe 1000 Delta IV launchers will put up enough mass to stitch enough tether together to make it happen for VERY SMALL payloads. At $200 million per Delta IV launch, thats $200 billion for launch costs alone, never mind the cost of building it. Good luck squeezing that out of congress.

Oh, and even once you build a space elevator, at the rates that climbers can climb the tether, a trip to GSO is going to take over a month for even a small payload. That is going to severely crimp the potential throughput of a tether and is what ultimately will nix it from being built purely on economics.

Now, that all said, I am also going to deal with the claim that ME-thruster concept is unsupported by any evidence. There have been, in fact, some four or five researchers who have all replicated Woodward's results.

And yes, the amount of thrust today is small, but the physics behind it show that it is scalable with the strength of the dielectric materials and will eventually enable high thrust to weight ratios like rocket engines, and even Alcubierre warp drive capabilities once the power density reaches a certain point.

Oh, and NASA identified mach effect thrusters as the greatest potential for breakthrough physics propulsion.

Giorgio
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Post by Giorgio »

IntLibber wrote: There have been, in fact, some four or five researchers who have all replicated Woodward's results.

Oh, and NASA identified mach effect thrusters as the greatest potential for breakthrough physics propulsion.
Do you have any sources for both claims?

GIThruster
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Post by GIThruster »

Jim Woodward's first exploration into M-E thrusters was over a decade ago when he was working with Tom Mayhood, who was his graduate student at the time. The test results of those early studies are impressive, as are the videos of the torque pendulum moving under it's own thrust.

Those were UFG studies. After that time, Jim came upon the design of the MLT in order to sidestep the acoustic impedance issues in the UFG design. After several years study by people like Jim, Paul and others, Jim realized that the MLT does not provide the bulk acceleration necessary for an efficient thruster. In the MLT, only the mobile ion inside the ceramic lattice moves, which is why it was thought to avoid the impedance issue--but the theory behind the thrusters really does say it needs "bulk" acceleration, meaning the entire ceramic lattice; and the MLT never provided this which is why one presumes results were disappointing.

About 7 years ago, Paul did his own MLT studies, and though he was not able to provide the necessary scientific controls (like vacuum) he did record significant thrusts--the highest thrust claims to date. If these test's are to be trusted, that thrust is certainly the result of the much higher frequency his design operated at. M-E scales with the cube of frequency.

After the MLT, Jim began work on the M-E Rotator which is not a thruster, but which does demonstrate M-E. Those results are posted on the web along with a video of the apparatus running. These are impressive results but they are convincing--not compelling--since they do not demonstrate thrust. If you want to compel people to sit up and take notice, you have to generate thrust.

Jim is now back working on the UFG. Hopefully we'll see some interesting test results in the next 3 months or so. He's using PZT not only in the actuator stacks, but as the active ceramic/cap as well, which one hopes will mitigate the previous acoustic impedance issues.

FYI, I was hired about 6 years ago to survey the advanced propulsion technologies that are emerging and identify those worthy of investment by the private sector. My finding was that ONLY Jim Woodward's work is worth such investment. Lock-Mart did the same study the year before I did and came to the same conclusion (I found out later.) NASA did their BPPP and identified a small handful of techs worth investigation, but those included supposed effects that had no theory to explain them, like Podkletnov's work. NASA did invest in some study of both Pod's work and the MLT, but that work never got off the ground before funding was cut.

IMHO, you have to be a dope to invest in Podkletnov's work seeing that there is no theory to explain why it ought to work, and it's darn expensive to investigate. I think the reason Pod's work gets the attention it does, as well as stuff like Tajmar's work (which is a follow-on) is because people DON'T understand what's there and so there's no patent, and an opportunity for fortune and glory. Stupid reason to invest. . .IMHO.

I'm not sure it's fair to say NASA identified M-E as the tech with the greatest potential for breakthrough propulsion. The BPPP never made a recommendation as to which tech it considered had the greatest potential. It is noteworthy, however; that NASA only pressed forward on 2 tech investigations, Woodward's and Pod's, and that there is/was no theory in support of Pod's claims and there has never been any replication success either. Fact is, Pod wants an outrageous amount of money to do the work at all--you'd be aghast at how much money he wanted from Boeing to work for them. Looks like a scam.

Woodward really does stand alone in many ways, especially including that he consistently turns down funding and finances his work out of his own pocket..
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

GIThruster
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Post by GIThruster »

Giorgio wrote:The issue is not really that it costs too much, but that there is no immediate return for that investment.

If there was a suitable economic reason to go there be sure that we would have already some colonies on the moon and Mars.
Just look back at what happened with the discovery of America.
Well there are two separate issue intertwined here. The first is the mandate for exploration--what the human space program has always been about. For that you don't need any return on investment (ROI). The return is seen in terms of scientific understanding, and accompanied by spin offs, but in general, there is no bottom-line ROI involved.

The second issue concerns the private sector and ROI. If space travel can be made economically viable, we can see more than a handful of specially chosen astronauts take to the heavens. If we can make space travel safe, quick, convenient and economical, then we can have our Golden Age of human spaceflight, comparable to the golden ages of say, sail across the Atlantic, steam travel, rail, and most importantly for comparison, the golden age of air travel.

It's important to keep these two issues separate in order to think clearly about them. What one can justify for one set of goals cannot be used to justify another. This is why we cannot say that reduced costs for launch to LEO justifies spending hundreds of billions of dollars. That argument ONLY obtains if you're looking at ROI and economic viability. If on the other hand, you're looking at the exploration issue, building a trillion dollar infrastructure is NEVER going to happen.

BTW, once you have your stuff at the top of the elevator, you have to then use it for something. THAT SOMETHING is more expensive than the elevator itself. That's why scenarios like the elevator are never going to happen. The only way we'll see that order of investment, is if it generates a huge ROI in the private sector, which means a space transport system that has virtually NO INFRASTRUCTURE, like the beginnings of general and commercial aviation.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Giorgio
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Post by Giorgio »

@ GIThruster

You are right of course.
My intention anyhow was not to make such a differentiation, but just an utopistic consideration that if there was an actual immediate return for sending people in space we would not have to worry about government or other agency to find ways to do it. People would take care about it.

Your consideration on the other hand is related to the real and actual situation of space exploration, and is completely correct.

paulmarch
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Location: Friendswood, TX USA

Post by paulmarch »

GIThruster wrote:Jim Woodward's first exploration into M-E thrusters was over a decade ago when he was working with Tom Mayhood, who was his graduate student at the time. The test results of those early studies are impressive, as are the videos of the torque pendulum moving under it's own thrust.

Those were UFG studies. After that time, Jim came upon the design of the MLT in order to sidestep the acoustic impedance issues in the UFG design. After several years study by people like Jim, Paul and others, Jim realized that the MLT does not provide the bulk acceleration necessary for an efficient thruster. In the MLT, only the mobile ion inside the ceramic lattice moves, which is why it was thought to avoid the impedance issue--but the theory behind the thrusters really does say it needs "bulk" acceleration, meaning the entire ceramic lattice; and the MLT never provided this which is why one presumes results were disappointing.

About 7 years ago, Paul did his own MLT studies, and though he was not able to provide the necessary scientific controls (like vacuum) he did record significant thrusts--the highest thrust claims to date. If these test's are to be trusted, that thrust is certainly the result of the much higher frequency his design operated at. M-E scales with the cube of frequency.

After the MLT, Jim began work on the M-E Rotator which is not a thruster, but which does demonstrate M-E. Those results are posted on the web along with a video of the apparatus running. These are impressive results but they are convincing--not compelling--since they do not demonstrate thrust. If you want to compel people to sit up and take notice, you have to generate thrust.

Jim is now back working on the UFG. Hopefully we'll see some interesting test results in the next 3 months or so. He's using PZT not only in the actuator stacks, but as the active ceramic/cap as well, which one hopes will mitigate the previous acoustic impedance issues.

FYI, I was hired about 6 years ago to survey the advanced propulsion technologies that are emerging and identify those worthy of investment by the private sector. My finding was that ONLY Jim Woodward's work is worth such investment. Lock-Mart did the same study the year before I did and came to the same conclusion (I found out later.) NASA did their BPPP and identified a small handful of techs worth investigation, but those included supposed effects that had no theory to explain them, like Podkletnov's work. NASA did invest in some study of both Pod's work and the MLT, but that work never got off the ground before funding was cut.

IMHO, you have to be a dope to invest in Podkletnov's work seeing that there is no theory to explain why it ought to work, and it's darn expensive to investigate. I think the reason Pod's work gets the attention it does, as well as stuff like Tajmar's work (which is a follow-on) is because people DON'T understand what's there and so there's no patent, and an opportunity for fortune and glory. Stupid reason to invest. . .IMHO.

I'm not sure it's fair to say NASA identified M-E as the tech with the greatest potential for breakthrough propulsion. The BPPP never made a recommendation as to which tech it considered had the greatest potential. It is noteworthy, however; that NASA only pressed forward on 2 tech investigations, Woodward's and Pod's, and that there is/was no theory in support of Pod's claims and there has never been any replication success either. Fact is, Pod wants an outrageous amount of money to do the work at all--you'd be aghast at how much money he wanted from Boeing to work for them. Looks like a scam.

Woodward really does stand alone in many ways, especially including that he consistently turns down funding and finances his work out of his own pocket..

Ron:

What has been your commentary to the diamond based room temperature superconductor guy (Dr. Prins) on the attitude of the science and to a lesser extent the commercial communities in regards to embracing new paradigms like the M-E?

“It's no crime to realize that trying to convince those with decades of study at stake, to re-examine their beliefs, is going to be a major task. What I like so much about Kuhn is, despite he's not an epistemologist, he's identified the dynamic in history as one of failure--as a current paradigm repeatedly fails to answer certain kinds of puzzle questions, as it generates more and more "anomalies" that it cannot cope with, it earns the place of re-evaluation. That opens the door to revolution in science, as opposed to normal, evolution in science.”

Sadly it's not "crazy past understanding" why Jim and all the other M-E experimenters have to endure the curse of dealing with the details of the M-E implementations, for it still boils down to a matter of the required resource people having a belief or faith in Jim’s new M-E paradigm, or not.

(Dorothy clicking her ruby shoe heels together three times, and believing that she would be whisked home by an unknown agent, and be right about it!)

Yes, Jim’s rotary data from last year showed that an M-E like 2-omega signal was being generated, but unless you really understood the experiment from the ground up, it was not a conclusive test series because nobody has gone to the expense of replicating it yet. Jim's verified M-E thrust data to date, (Ref Tajmar’s 2006 Mach-6 MLT data that only showed a transient thrust signature due to the lack of a bulk acceleration component in the Mach-6 series of MLTs.), has never gone over a micro-Newton at best. A thrust level that can be expressed by any number of false positive sources no matter how many controls you think you have in place. And as you noted, I could never afford the required vacuum equipment needed to verify my 2004 and 2005 MLT multi milli-Newton results per the critic's requirements either.

When we can generate reversible milli-Newton plus thrusts in a hard vacuum of 1x10^-7 Torr or less, with self-contained M-E devices powered by its own local power supplies with the entire test article ensemble adequately shielded to cancel possible mundane electrostatic and electrodynamic effects with the vacuum chamber, we should start to see more outside funding interest, but not until then.

BTW, by pure dumb luck both the 2.2 MHz MLT-2004 and 2.15 and 3.8 MHz Mach-2MHz MLT test articles had flexible suspension systems that let them create a bulk acceleration of their respective cap rings under the influence of the MLT’s toroidal B-field coil applied vxB Lorentz force. The MLT-2004 cap ring was mounted in an RTV rubber sheath used to electrically isolate its cap ring from the over-rapped toroidal B-field coil, while the Mach-2MHz cap & toroidal B-field coil assembly was mounted on a Plexiglas dog-bone that acted as a very stiff spring optimized for high frequency response. And yes, I verified that all the electrical and mechanical force vectors in each test article were pushing in the right directions to generate a net thrust from the M-E. But alas even though the Mach-2MHz was in a Faraday shield, folks still got hung up on the remote possibility that there was some sort of ion wind effect going on…
Paul March
Friendswood, TX

TallDave
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Post by TallDave »

As soon as you start weaving them together, the tensile strength drops rather quickly.
This was all covered years ago -- there are calculations for various weaving schemes of ribbon and cable, and the effect of those limits on SE construction.

http://www.spaceward.org/elevator-feasibility
Based on a gradual convergence of experimental and theoretical results, the specific strength of raw CNTs will not exceed 50 MYuri [6],[7], as compared to previous estimates of 100 MYuri[4]. In particular, a failure mechanism known as the Stone-Wales causes spontaneous defects in the Nanotube structure and limits the possible strength.
Oh, and even once you build a space elevator, at the rates that climbers can climb the tether, a trip to GSO is going to take over a month for even a small payload. That is going to severely crimp the potential throughput of a tether and is what ultimately will nix it from being built purely on economics.
Assuming it can be built, throughput for an SE is probably very high.
The encouraging conclusion is that if a Space Elevator satisfies the Feasibility Condition, then during normal operations its minimum payload throughput is a very impressive TMR•(1+FS)/TD – easily 100 mmax per year when plugging in real-world numbers.

Yes, this is all very challenging, but no it isn't theoretically impossible with CNT, as it would be with common materials. That's why NASA is interested.

Hopefully Paul will get some good results, and they may become interested in M-E thrusters as well.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

GIThruster
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Post by GIThruster »

paulmarch wrote:
GIThruster wrote:Jim Woodward's first exploration into M-E thrusters was over a decade ago when he was working with Tom Mayhood, who was his graduate student at the time. The test results of those early studies are impressive, as are the videos of the torque pendulum moving under it's own thrust.

Those were UFG studies. After that time, Jim came upon the design of the MLT in order to sidestep the acoustic impedance issues in the UFG design. After several years study by people like Jim, Paul and others, Jim realized that the MLT does not provide the bulk acceleration necessary for an efficient thruster. In the MLT, only the mobile ion inside the ceramic lattice moves, which is why it was thought to avoid the impedance issue--but the theory behind the thrusters really does say it needs "bulk" acceleration, meaning the entire ceramic lattice; and the MLT never provided this which is why one presumes results were disappointing.

About 7 years ago, Paul did his own MLT studies, and though he was not able to provide the necessary scientific controls (like vacuum) he did record significant thrusts--the highest thrust claims to date. If these test's are to be trusted, that thrust is certainly the result of the much higher frequency his design operated at. M-E scales with the cube of frequency.

After the MLT, Jim began work on the M-E Rotator which is not a thruster, but which does demonstrate M-E. Those results are posted on the web along with a video of the apparatus running. These are impressive results but they are convincing--not compelling--since they do not demonstrate thrust. If you want to compel people to sit up and take notice, you have to generate thrust.

Jim is now back working on the UFG. Hopefully we'll see some interesting test results in the next 3 months or so. He's using PZT not only in the actuator stacks, but as the active ceramic/cap as well, which one hopes will mitigate the previous acoustic impedance issues.

FYI, I was hired about 6 years ago to survey the advanced propulsion technologies that are emerging and identify those worthy of investment by the private sector. My finding was that ONLY Jim Woodward's work is worth such investment. Lock-Mart did the same study the year before I did and came to the same conclusion (I found out later.) NASA did their BPPP and identified a small handful of techs worth investigation, but those included supposed effects that had no theory to explain them, like Podkletnov's work. NASA did invest in some study of both Pod's work and the MLT, but that work never got off the ground before funding was cut.

IMHO, you have to be a dope to invest in Podkletnov's work seeing that there is no theory to explain why it ought to work, and it's darn expensive to investigate. I think the reason Pod's work gets the attention it does, as well as stuff like Tajmar's work (which is a follow-on) is because people DON'T understand what's there and so there's no patent, and an opportunity for fortune and glory. Stupid reason to invest. . .IMHO.

I'm not sure it's fair to say NASA identified M-E as the tech with the greatest potential for breakthrough propulsion. The BPPP never made a recommendation as to which tech it considered had the greatest potential. It is noteworthy, however; that NASA only pressed forward on 2 tech investigations, Woodward's and Pod's, and that there is/was no theory in support of Pod's claims and there has never been any replication success either. Fact is, Pod wants an outrageous amount of money to do the work at all--you'd be aghast at how much money he wanted from Boeing to work for them. Looks like a scam.

Woodward really does stand alone in many ways, especially including that he consistently turns down funding and finances his work out of his own pocket..

Ron:

What has been your commentary to the diamond based room temperature superconductor guy (Dr. Prins) on the attitude of the science and to a lesser extent the commercial communities in regards to embracing new paradigms like the M-E?

“It's no crime to realize that trying to convince those with decades of study at stake, to re-examine their beliefs, is going to be a major task. What I like so much about Kuhn is, despite he's not an epistemologist, he's identified the dynamic in history as one of failure--as a current paradigm repeatedly fails to answer certain kinds of puzzle questions, as it generates more and more "anomalies" that it cannot cope with, it earns the place of re-evaluation. That opens the door to revolution in science, as opposed to normal, evolution in science.”

Sadly it's not "crazy past understanding" why Jim and all the other M-E experimenters have to endure the curse of dealing with the details of the M-E implementations, for it still boils down to a matter of the required resource people having a belief or faith in Jim’s new M-E paradigm, or not.

(Dorothy clicking her ruby shoe heels together three times, and believing that she would be whisked home by an unknown agent, and be right about it!)

Yes, Jim’s rotary data from last year showed that an M-E like 2-omega signal was being generated, but unless you really understood the experiment from the ground up, it was not a conclusive test series because nobody has gone to the expense of replicating it yet. Jim's verified M-E thrust data to date, (Ref Tajmar’s 2006 Mach-6 MLT data that only showed a transient thrust signature due to the lack of a bulk acceleration component in the Mach-6 series of MLTs.), has never gone over a micro-Newton at best. A thrust level that can be expressed by any number of false positive sources no matter how many controls you think you have in place. And as you noted, I could never afford the required vacuum equipment needed to verify my 2004 and 2005 MLT multi milli-Newton results per the critic's requirements either.

When we can generate reversible milli-Newton plus thrusts in a hard vacuum of 1x10^-7 Torr or less, with self-contained M-E devices powered by its own local power supplies with the entire test article ensemble adequately shielded to cancel possible mundane electrostatic and electrodynamic effects with the vacuum chamber, we should start to see more outside funding interest, but not until then.

BTW, by pure dumb luck both the 2.2 MHz MLT-2004 and 2.15 and 3.8 MHz Mach-2MHz MLT test articles had flexible suspension systems that let them create a bulk acceleration of their respective cap rings under the influence of the MLT’s toroidal B-field coil applied vxB Lorentz force. The MLT-2004 cap ring was mounted in an RTV rubber sheath used to electrically isolate its cap ring from the over-rapped toroidal B-field coil, while the Mach-2MHz cap & toroidal B-field coil assembly was mounted on a Plexiglas dog-bone that acted as a very stiff spring optimized for high frequency response. And yes, I verified that all the electrical and mechanical force vectors in each test article were pushing in the right directions to generate a net thrust from the M-E. But alas even though the Mach-2MHz was in a Faraday shield, folks still got hung up on the remote possibility that there was some sort of ion wind effect going on…
Paul, I agree save that I doubt E-7 T is necessary. If you get the same thrust at E-5 as you get at ambient, then you know you don't need harder vacuum. If you, Bruce and I or Jim can generate milli-Newton thrusts on the ARC Lite (which as I recall is limited to E-6T?) I have to hope we're in business.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

paulmarch
Posts: 155
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Location: Friendswood, TX USA

Post by paulmarch »

"Paul, I agree save that I doubt E-7 T is necessary. If you get the same thrust at E-5 as you get at ambient, then you know you don't need harder vacuum. If you, Bruce and I or Jim can generate milli-Newton thrusts on the ARC Lite (which as I recall is limited to E-6T?) I have to hope we're in business."

Ron:

A vacuum pressure of 1.0e-7 Torr is used by the vacuum cap and relay manufacturers to guarantee that no glow discharge or ion wind currents will be activated. However your comment about comparing the air based thrust signature with the thrust signature at 1.0e-5 Torr does hold some merit, but for whom? The skeptics will no doubt pile-on and say the system still MIGHT generate some ion wind thrust signatures even at that low a pressure level, especially if we are again only talking about micro-Newton thrust levels.

In regards to Jim’s ARC-Lite setup, his vacuum level has never gone below 1.0e-3 Torr since he has never installed a second-stage oil diffusion or turbo-molecular vacuum pump in parallel with his old Welch roughing pump used with his Plexiglas vacuum chamber. That’s one area where Jim really does need to improve his setup, but it will cost him at least $5k or more to do so…
Paul March
Friendswood, TX

MSimon
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Post by MSimon »

Paul,

I'm sure you know this: if the budget allows go for the turbo-pump. If you have H2 and He worries a small pump in series with the main pump will help.

Think of the turbo-pump as insurance for the rest of your set-up.

The turbo pump goes in series with the backing pump as the max back pressure they can handle is around 1E-2.
Engineering is the art of making what you want from what you can get at a profit.

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