GIThruster wrote:I appreciate you drawing a distinction between fringe and what I like to call "emergent" science. Yes indeed, when i was hired back in 2005 to survey all the supposed "breakthrough propulsions schemes", I found that the only one worthy of investment was the M-E research. LI found out later that LochMart had done a similar survey and come to the same conclusion.
Much of the work is continuing to use the same sorts of materials and designs from more than a decade ago. I'm hoping that when Jim's book comes out, we'll see an explosion of interest that opens up some finding and allows access to new materials like single crystal CCTO, that has k values up to 100,000. Right now, Jim is using PZT that has a k of less than 1,000. Force generated by his UFG scales with the square of the k, so you can see why access to CCTO could be a breakthrough issue.
CCTO is one of the materials I know of. CCTO dielectric constant declines with increased temperature and frequency. LNSO (La15/8Sr1/8NiO4) is another that may be better than CCTO. The polymer that I referred to previously is P(VDF-TrFE) which may or may not work out as a high dielectric material. These materials are being developed for supercapacitor applications for consumer electronics, electric vehicles, and renewable energy storage.
I agree that M-E is the only plausible possibility for breakthrough propulsion.
Thanks for that. I have been watching the CCTO stuff too. The trouble is, the really fabulous stuff is single crystal, and there are no commercial providers for this. With BaTiO3, you can find cheap single crystal targets but they are unpolarized and have no electrodes sputtered on. That is an obtainable goal if one can find a cheap way to sputter.
CCTO is however really startling stuff. I recently found this:
and the idea of 70,000 k running at 500 Mhz is pretty enticing. What we haven't found are electromechanical linking coefficients for the material. We don't know how much bulk acceleration it would provide.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
I have a sputter system and can deposit copper tantalum niobium ect . It can cover an area of about 600 cm sq. Would you consider free to be low cost sputtreing ?
GIThruster wrote:Thanks for that. I have been watching the CCTO stuff too. The trouble is, the really fabulous stuff is single crystal, and there are no commercial providers for this. With BaTiO3, you can find cheap single crystal targets but they are unpolarized and have no electrodes sputtered on. That is an obtainable goal if one can find a cheap way to sputter.
CCTO is however really startling stuff. I recently found this:
and the idea of 70,000 k running at 500 Mhz is pretty enticing. What we haven't found are electromechanical linking coefficients for the material. We don't know how much bulk acceleration it would provide.
I found this paper, and others, last year in the research library near where I live. CCTO, LNSO, and other materials make up a family of CTC materials. I agree that single crystal is the only way to go for M-E applications. These materials are new and manufacturing processes for them are just being developed. These materials are necessary for realization of M-E technology.
GIThruster wrote:Thanks for that. I have been watching the CCTO stuff too. The trouble is, the really fabulous stuff is single crystal, and there are no commercial providers for this. With BaTiO3, you can find cheap single crystal targets but they are unpolarized and have no electrodes sputtered on. That is an obtainable goal if one can find a cheap way to sputter.
CCTO is however really startling stuff. I recently found this:
and the idea of 70,000 k running at 500 Mhz is pretty enticing. What we haven't found are electromechanical linking coefficients for the material. We don't know how much bulk acceleration it would provide.
I found this paper, and others, last year in the research library near where I live. CCTO, LNSO, and other materials make up a family of CTC materials. I agree that single crystal is the only way to go for M-E applications. These materials are new and manufacturing processes for them are just being developed. These materials are necessary for realization of M-E technology.
CDCs have low breakdown, the mechanism for polarization is not squeezing the lattice, but large movement of charge carriers. So I doubt they would help, not enough energy storage.
tomclarke wrote:
CDCs have low breakdown, the mechanism for polarization is not squeezing the lattice, but large movement of charge carriers. So I doubt they would help, not enough energy storage.
I'm not following entirely. You're saying that it's the mobile ion's movement that stores the energy and that the material shows very little piezoaction, or movement of the lattice?
At the frequencies Jim uses in his UFG work, some of these test results from Augsburg are of k's above 500,000. I can't imagine how that could happen without the lattice displacing. Likewise, the Augsburg folk say that CCTO is not an ideal energy storage ceramic, because it has a high dielectric loss. Well, isn't such loss a function of motion in the lattice?
Pg 3 here as K's over 500,000 and the last paragraph on page 8 has the note about loss tangent:
tomclarke wrote:
CDCs have low breakdown, the mechanism for polarization is not squeezing the lattice, but large movement of charge carriers. So I doubt they would help, not enough energy storage.
I'm not following entirely. You're saying that it's the mobile ion's movement that stores the energy and that the material shows very little piezoaction, or movement of the lattice?
At the frequencies Jim uses in his UFG work, some of these test results from Augsburg are of k's above 500,000. I can't imagine how that could happen without the lattice displacing. Likewise, the Augsburg folk say that CCTO is not an ideal energy storage ceramic, because it has a high dielectric loss. Well, isn't such loss a function of motion in the lattice?
Pg 3 here as K's over 500,000 and the last paragraph on page 8 has the note about loss tangent:
CCTO and the other CTC's still have too high of dielectric loss. Also, the dielectric constant for CCTO rolls off in the low MHz regime. LNSO tends to maintain its dielectric constant up to 50-100MHz (which is the ideal operating regime for M-E application), but still has too high of dielectric loss. These papers report results with sintered form of the material. I don't know if single-crystal form would have improved dielectric loss.
If these materials can be optimized for M-E application, they will definitely make a thruster possible (assuming that M-E is real, of course).
tomclarke wrote:
CDCs have low breakdown, the mechanism for polarization is not squeezing the lattice, but large movement of charge carriers. So I doubt they would help, not enough energy storage.
I'm not following entirely. You're saying that it's the mobile ion's movement that stores the energy and that the material shows very little piezoaction, or movement of the lattice?
At the frequencies Jim uses in his UFG work, some of these test results from Augsburg are of k's above 500,000. I can't imagine how that could happen without the lattice displacing. Likewise, the Augsburg folk say that CCTO is not an ideal energy storage ceramic, because it has a high dielectric loss. Well, isn't such loss a function of motion in the lattice?
Pg 3 here as K's over 500,000 and the last paragraph on page 8 has the note about loss tangent:
The mechanisms behind these high k dielectrics are well enough understood. They have electrons that move more than one lattice cell. There are variations, but that is the basic idea, and it goes with very low breakdown field. Electrons, not ions, create the polarization.
The dielectric loss is because the electrons lose energy as they move.
Ah, I think you're talking about "Charge Density Waves"? From the link:
Charge-Density Waves
In highly anisotropic, approximately one-dimensional materials a charge-density wave (CDW) can form. Here the charge density is a periodic function of position and its period can be incommensurate with the crystal lattice. The dielectric behavior of CDW systems shows two characteristic features: A harmonic oscillator mode at GHz frequencies caused by the CDW being pinned at defects and a huge relaxation mode at kHz-MHz involving extremely large values of the dielectric constant, whose true origin is not completely clarified. The dynamics of CDW systems, including their dielectric response, is treated in detail in the review article by G. Grüner [Gru88].
I think though, the "huge relaxation" is speaking of the lattice, so we ought to have both very high de/dt and significant mechanical action. I think the reference that the wave or group of electrons, can move at Ghz frequencies is a nod to what you're saying--most perovskites can't do that as they have an ionic response time limited by the lattice of 1-2 Ghz. This phenomenon with the electrons moving larger distances is fine if it boosts the k. I'm still not seeing the troube you're seeing and this is probably my fault since I don't understand how super-high k can be low energy, but I'm all ears.
If I am following though, perhaps what you're saying is that the high loss can't be attributed to the lattice, which means it doesn't cause greater than average displacement for a perovskite. That would be okay. Perovskites generate thousands or millions of gee accelerations in things like PZT and BaTiO3. Frankly, we don't need to improve that (and indeed, this would cause us worse preloading issues than we already have.) It's the power density that needs improvement. 500,000 k is a pretty huge improvement. If the problem you're suggesting is inadequate standoff--the electrons will just run out of the ceramic--then I can't understand what generates such a high k value.
Last edited by GIThruster on Wed Feb 01, 2012 8:37 pm, edited 2 times in total.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
GIThruster wrote:Ah, I think you're talking about "Charge Density Waves"? From the link:
Charge-Density Waves
In highly anisotropic, approximately one-dimensional materials a charge-density wave (CDW) can form. Here the charge density is a periodic function of position and its period can be incommensurate with the crystal lattice. The dielectric behavior of CDW systems shows two characteristic features: A harmonic oscillator mode at GHz frequencies caused by the CDW being pinned at defects and a huge relaxation mode at kHz-MHz involving extremely large values of the dielectric constant, whose true origin is not completely clarified. The dynamics of CDW systems, including their dielectric response, is treated in detail in the review article by G. Grüner [Gru88].
I think though, the "huge relaxation" is speaking of the lattice, so we ought to have both very high de/dt and significant mechanical action. I think the reference that the wave or group of electrons, can move at Ghz frequencies is a nod to what you're saying--most perovskites can't do that as they have an ionic response time limited by the lattice of 1-2 Ghz. This phenomenon with the electrons moving larger distances is fine if it boosts the k. I'm still not seeing the troube you're seeing and this is probably my fault since I don't understand how super-high k can be low energy, but I'm all ears.
I mean IBLC/GBLC dielectrics, which have been much misunderstood over the last 15 years. But now there is a consensus. The high k is electron movement outside the lattice. You can't get high k from normal ion movement in the lattice.
Super high k is low energy because the electrons move at low voltage and E = Q*V.
In fact even with ceramics, higher k => lower ED above an optimum value which is pretty low.
Well, what you're saying does indeed sound like "no game here". Do you mind if I copy your comments here to a private mail list discussing this, or would you like to join the list?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
GIThruster, i remain troubled by the specific charge that there is a math error right in plain sight at the beginning of Woodward's derivation. I am clearly not a physicist but this charge, and specifically that it stems from incorrectly setting Phi as a variable has been leveled by numerous physicists including Lubos Motl in 2009, Steve Lajoie in 2011, and an additional one in 2010 that i can't seem to find right now (buried in the NSF thread somewhere).
Additionally others have dismissed the entire theory as stemming from carrying out a math error from the beginning. If the charge is not true than it at least serves as the root source of a large legend about ME theory.
Woodward's response to this specific charge as I understand it has been to repeat 2 things: 1) "there is no error in the derivation". 2) "the derivation has been peer reviewed and found to be without error."
I understand it's impossible to prove the non-existence of a negative. But wouldn't it be useful to address this specifically the way the ORNL argument about mass and momentum was? There are so few qualified to expound on the answer or explain why it is appropriate to set up the equation this way I hope Woodward will address it in the book at least if not online.
Tom.Cuddihy
~~~~~~~~~~~~~~~~~~~~~
Faith is the foundation of reason.
I'm not sure what it is you're recommending precisely. Lubos Motl has a history of slandering people while failing to answer them in the refereed journals. Isn't this why he was run out of Harvard, because of his attacks on Lee Smolin that he never bothered to dignify with a real peer reviewed treatment? Motl killed his career in the big time physics world through his lazy, sloppy public commentary, as this is antithetical to how science gets done.
Steve Lajoie is not a physicist. He's an engineer whom never understood any of Jim's work. I answered his complaints over at the Physics Forum and I don't think he deserves more a treatment than that. He has not asked for one nor answered my responses nor those of Paul March. (I just checked.) Certainly, I doubt Jim would give it his own attention.
Peer review exists for just these sorts of reasons, so proponents of a theory don't have to make endless responses to ill-conceived objections by anyone who happens by. I think the almost 20 years since Jim's theory was first published have shown that informal detractors don't earn answers just from being loud or obnoxious.
And let me especially take note of one particularly salient detail in this regard: for almost 20 years, the advanced propulsion community has been dominated by the ZPFer's. All through the BPPP investigation and since, ZPF has had the vast bulk of interest in the field. Despite this, there is no evidence for ZPF as the origin of inertia, just as there is no evidence for virtual particles.
Given that this is the situation, with M-E theory publishing yearly and providing concrete evidence, in the face of it's fierce competitor, the ZPF gremlin; does it seem reasonable to anyone that a math error could have made it through peer review time and again for almost 20 years?
Not.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis
Can you shoot me your email so I can forward it to those whom might work out a plan with you?