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#21
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Startling amounts of stored energy in fully ionized plasmas.
On Oct 28, 6:09 pm, Robert Clark wrote:
... The problem with the storage of these ions at high density is that you have to overcome the large electrostatic repulsion between them when they are close together. Then what might work would be methods of screening out the electric field between the ions. I asked about methods of accomplishing this he Newsgroups: sci.physics, sci.physics.relativity From: Date: 7 Jul 2005 10:42:54 -0700 Local: Thurs, Jul 7 2005 1:42 pm Subject: Expelling an electric field.http://groups.google.com/group/sci.p...d/thread/aff52... One suggested solution was the Faraday Cage: Faraday cage.http://en.wikipedia.org/wiki/Faraday_cage I had thought that the Faraday cage wouldn't prevent the electric field from escaping but as described in the wikipedia page if the cage is grounded then effectively the charge and the field inside would be contained. Would the ground though eventually drain off the charge inside? If this works we could have a highly conducting metal, ideally a "perfect" conductor, surrounding a group of charges thus reducing the electrostatic repulsion that had to be restrained. We would have to have a ground wire connected to each cage around the group of charges. Since we want high density each metal cage would have to be nanoscopically thin. Is there a limit to how well the cage can work dependent on its thickness? We would also have to have a method of accessing the ions to be able to extract the electron recombinationenergyin the case of ion storage or the matter-antimatter conversionenergyin the case of positron storage. Bob Clark Hmm. An interesting question: would you have to have the electric fields prevented from exiting the Faraday cages? Would simply having the electric fields from the charges being prevented from entering the cages of the other charges be sufficient? In that case you wouldn't need to have the cages be grounded. Another question: could you have the cages contacting each other to save even more space? In this case it would be like having a 3- dimensional metal lattice of hollow little cubes with a charge or group of charges inside each cube. Bob Clark I found this report that fullerenes can act as Faraday cages at the nanoscale: C60 as a Faraday cage. Appl. Phys. Lett. -- January 19, 2004 -- Volume 84, Issue 3, pp. 431-433. "Endohedral fullerenes have been proposed for a number of technological uses, for example, as a nanoscale switch, memory bit and as qubits for quantum computation. For these technology applications, it is important to know the ease with which the endohedral atom can be manipulated using an applied electric field. We find that the Buckminsterfullerene (C60) acts effectively as a small Faraday cage, with only 25% of the field penetrating the interior of the molecule. Thus influencing the atom is difficult, but as a qubit the endohedral atom should be well shielded from environmental electrical noise. We also predict how the field penetration should increase with the fullerene radius." http://titus.phy.qub.ac.uk/group/Pau...2004_43 1.pdf This discusses though that the electric field is screened down only to 25% of its external value. This is probably because carbon is not normally the best of conductors. If a similar nanoscale cage could be produced of better conducting metals it should result in near 100% screening. This also quite likely would work with carbon nanotubes formed into cylindrical cages since the nanotubes can be formed with end caps. It is known that nanotubes can be conducting or semiconducting according to the orientation of the carbon atoms: Carbon nanotube. "Electrical Because of the symmetry and unique electronic structure of graphene, the structure of a nanotube strongly affects its electrical properties. For a given (n,m) nanotube, if n - m is a multiple of 3, then the nanotube is metallic, otherwise the nanotube is a semiconductor. Thus all armchair (n=m) nanotubes are metallic, and nanotubes (5,0), (6,4), (9,1), etc. are semiconducting. In theory, metallic nanotubes can have an electrical current density more than 1,000 times greater than metals such as silver and copper." http://en.wikipedia.org/wiki/Carbon_nanotube#Electrical How metallic are metal nanotubes? By Kimberly Patch, Technology Research News May 30, 2001 http://www.trnmag.com/Stories/053001...es_053001.html Another possibility comes from the fact that the spherical fullerenes can come in nested form: CARBON ONIONS. Number 101 (Story #1), October 30, 1992 http://www.aip.org/pnu/1992/split/pnu101-1.htm Bonding Bucky-Onions. 13 November 2001 http://focus.aps.org/story/v8/st27 The fullerene "onions" can come in up to 70 shells. Then if a single shell fullerene reduces the electric field inside by 1/4, five layers should reduce it by a factor of about 1/1,000 and ten layers by about 1/1,000,000. Bob Clark |
#22
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Startling amounts of stored energy in fully ionized plasmas.
On Oct 12, 3:56 am, Craig Markwardt
wrote: This is not really a good method for storing energy. The losses are too rapid. In order to maintain (say) Xenon in a fully ionized state, a Boltzmann equilibrium must be achieved. Removing the last two electrons of Xenon takes ~40 keV each (ref. X-ray Data Book, xdb.lbl.gov). Thus, the temperature must be (kB T 40 keV) where kB is the Boltzmann constant. Let's say kB T = 100 keV, or a temperature of 1 billion Kelvins. That is hot. Your assumption is flawful. Screw Boltzmann equilibrium: Do you discount the storing of a bomb by the equilibrial states of its decay products? Hydrogen plasma is permanent in interstellar vacua, yet they're too cold to ionize ground-state hydrogen. The Bremsstrahlung emissivity of a plasma scales approximately as, W = 1.4e-34 ne nZ Z^2 T^(0.5) in Joule / s / cm^3 where ne is the electron density, nZ is the ion density, Z is the atomic number of the ion. (ne and nZ must be in cm^{-3}). Compare this to your quoted energy density of (200 keV / ion) = (3.2e-14 Joules / ion), or an energy density of E = 3.2e-14 nZ Joules / cm^3. No, emissivity scales with a ~, not a =, and hangs on emissanse, which can lie between 0 and 1. Even your "low" density of 4e14 ions/cm^3, the ratio of W / E is 1/(0.11 msec). In other words, all the internal (and ionization) energy of the plasma will leak out in less than 1 millisecond by bremsstrahlung radiation. This is radiation that can't be contained by any magnetic field or trap, so it is unavoidable. Not to mention the danger of carrying around a tank of 1 billion degree plasma... A lightning bolt cannot be contained, yet its charges obviosely can and are. You suck. -Aut |
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Startling amounts of stored energy in fully ionized plasmas.
On Nov 20, 11:19 pm, Robert Clark wrote:
This discusses though that the electric field is screened down only to 25% of its external value. This is probably because carbon is not normally the best of conductors. If a similar nanoscale cage could be produced of better conducting metals it should result in near 100% screening. This also quite likely would work with carbon nanotubes formed into cylindrical cages since the nanotubes can be formed with end caps. It is known that nanotubes can be conducting or semiconducting according to the orientation of the carbon atoms: 3D chain-links of nanotubular rings: start with cubes, then go for Borromean tetrahedra The fullerene "onions" can come in up to 70 shells. Then if a single shell fullerene reduces the electric field inside by 1/4, five layers should reduce it by a factor of about 1/1,000 and ten layers by about 1/1,000,000. Shielding drops off with size, remember? |
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Startling amounts of stored energy in fully ionized plasmas.
On Nov 21, 8:58 pm, "Autymn D. C." wrote:
On Nov 20, 11:19 pm, Robert Clark wrote: This discusses though that the electric field is screened down only to 25% of its external value. This is probably because carbon is not normally the best of conductors. If a similar nanoscale cage could be produced of better conducting metals it should result in near 100% screening. This also quite likely would work with carbon nanotubes formed into cylindrical cages since the nanotubes can be formed with end caps. It is known that nanotubes can be conducting or semiconducting according to the orientation of the carbon atoms: 3D chain-links of nanotubular rings: start with cubes, then go for Borromean tetrahedra The fullerene "onions" can come in up to 70 shells. Then if a single shell fullerene reduces the electric field inside by 1/4, five layers should reduce it by a factor of about 1/1,000 and ten layers by about 1/1,000,000. Shielding drops off with size, remember? Yes the paper I referred to does mention they *calculated* the shielding should become worse with large size buckyballs: C60 as a Faraday cage. Appl. Phys. Lett. -- January 19, 2004 -- Volume 84, Issue 3, pp. 431-433. "Endohedral fullerenes have been proposed for a number of technological uses, for example, as a nanoscale switch, memory bit and as qubits for quantum computation. For these technology applications, it is important to know the ease with which the endohedral atom can be manipulated using an applied electric field. We find that the Buckminsterfullerene (C60) acts effectively as a small Faraday cage, with only 25% of the field penetrating the interior of the molecule. Thus influencing the atom is difficult, but as a qubit the endohedral atom should be well shielded from environmental electrical noise. We also predict how the field penetration should increase with the fullerene radius." http://titus.phy.qub.ac.uk/group/Pau...2004_43 1.pdf This might be because carbon is not normally a good conductor, much less the "perfect conductor" required for the Faraday cage do to complete screening. Ideally, though a Faraday cage does complete screening regardless of the size. BTW, here's a nice animation of how the electric field lines bend around a conducting cage: Isolated Cylinder http://socrates.berkeley.edu/~fajans...iles/frame.htm The applet showing this for some reason does not show up on my computer using the Firefox browser, but shows up well using IE. How well the nested buckyballs could do screening would have to be determined by experiment. Also, carbon can become superconducting at very low temperatures. I mentioned that you would get better screening using metal buckyballs. I don't know if this has been done but I found a report showing that it should be possible with boron (also not a metal): Bucky's brother -- The boron buckyball makes its debut. Published: 12:29 EST, April 23, 2007 http://www.physorg.com/news96550194.html Another consideration for space based applications is the mass of the cage compared with the mass of the charged particle it contained. If the particle was uranium, with an atomic mass of 238, contained in a single layer carbon fullerene C60, the ratio of the container to the ions would be 60x12 = 720 to 238, or 3 to 1. Ideal would be a light metal that could be formed into a single atomic layer cage. Lithium for example is classified as an alkali metal with a conductivity more than 100 times that of carbon: Lithium. http://www.chemicool.com/elements/lithium.html Carbon. http://www.chemicool.com/elements/carbon.html Bob Clark |
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Startling amounts of stored energy in fully ionized plasmas.
On Nov 22, 10:47 am, Robert Clark wrote:
On Nov 21, 8:58 pm, "Autymn D. C." wrote: ... The fullerene "onions" can come in up to 70 shells. Then if a single shell fullerene reduces the electric field inside by 1/4, five layers should reduce it by a factor of about 1/1,000 and ten layers by about 1/1,000,000. Shielding drops off with size, remember? Yes the paper I referred to does mention they *calculated* the shielding should become worse with large size buckyballs: C60 as a Faraday cage. Appl. Phys. Lett. -- January 19, 2004 -- Volume 84, Issue 3, pp. 431-433. "Endohedral fullerenes have been proposed for a number of technological uses, for example, as a nanoscale switch, memory bit and as qubits for quantum computation. For these technology applications, it is important to know the ease with which the endohedral atom can be manipulated using an applied electric field. We find that the Buckminsterfullerene (C60) acts effectively as a small Faraday cage, with only 25% of the field penetrating the interior of the molecule. Thus influencing the atom is difficult, but as a qubit the endohedral atom should be well shielded from environmental electrical noise. We also predict how the field penetration should increase with the fullerene radius."http://titus.phy.qub.ac.uk/group/Paul/publications/2004/Delaney_Greer... This might be because carbon is not normally a good conductor, much less the "perfect conductor" required for the Faraday cage do to complete screening. Ideally, though a Faraday cage does complete screening regardless of the size. BTW, here's a nice animation of how the electric field lines bend around a conducting cage: Isolated Cylinderhttp://socrates.berkeley.edu/~fajans/Teaching/cartoons/Shielding/Test... The applet showing this for some reason does not show up on my computer using the Firefox browser, but shows up well using IE. How well the nested buckyballs could do screening would have to be determined by experiment. Also, carbon can become superconducting at very low temperatures. I mentioned that you would get better screening using metal buckyballs. I don't know if this has been done but I found a report showing that it should be possible with boron (also not a metal): Bucky's brother -- The boron buckyball makes its debut. Published: 12:29 EST, April 23, 2007http://www.physorg.com/news96550194.html Another consideration for space based applications is the mass of the cage compared with the mass of the charged particle it contained. If the particle was uranium, with an atomic mass of 238, contained in a single layer carbon fullerene C60, the ratio of the container to the ions would be 60x12 = 720 to 238, or 3 to 1. Ideal would be a light metal that could be formed into a single atomic layer cage. Lithium for example is classified as an alkali metal with a conductivity more than 100 times that of carbon: Lithium.http://www.chemicool.com/elements/lithium.html Carbon.http://www.chemicool.com/elements/carbon.html Bob Clark Just did a web search and found "buckyballs" have been made of gold, which of course is an excellent conductor: Buckyballs Make Room For Gilded Cages. ScienceDaily (May 16, 2006) -- "Scientists have uncovered a class of gold atom clusters that are the first known metallic hollow equivalents of the famous hollow carbon fullerenes known as buckyballs." .... "The fullerene is made up of a sphere of 60 carbon (C) atoms; gold (Au) requires many fewer--16, 17 and 18 atoms, in triangular configurations more gem-like than soccer ball. At more than 6 angstroms across, or roughly a ten-millionth the size of this comma, they are nonetheless roomy enough to cage a smaller atom." http://www.sciencedaily.com/releases...0516075733.htm Gold though is quite heavy at an atomic weight of nearly 200. So even with the gold cage containing 16 atoms it still would be heavier than the C60 cage. Still it would be interesting to find out how good the gold cages are at screening electric charge. Bob Clark |
#26
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Startling amounts of stored energy in fully ionized plasmas.
On Nov 22, 10:47 am, Robert Clark wrote:
On Nov 21, 8:58 pm, "Autymn D. C." wrote: On Nov 20, 11:19 pm, Robert Clark wrote: This discusses though that the electric field is screened down only to 25% of its external value. This is probably because carbon is not normally the best of conductors. If a similar nanoscalecagecould be produced of better conducting metals it should result in near 100% screening. This also quite likely would work with carbon nanotubes formed into cylindrical cages since the nanotubes can be formed with end caps. It is known that nanotubes can be conducting or semiconducting according to the orientation of the carbon atoms: 3D chain-links of nanotubular rings: start with cubes, then go for Borromean tetrahedra The fullerene "onions" can come in up to 70 shells. Then if a single shell fullerene reduces the electric field inside by 1/4, five layers should reduce it by a factor of about 1/1,000 and ten layers by about 1/1,000,000. Shielding drops off with size, remember? Yes the paper I referred to does mention they *calculated* the shielding should become worse with large size buckyballs: C60 as aFaradaycage. Appl. Phys. Lett. -- January 19, 2004 -- Volume 84, Issue 3, pp. 431-433. "Endohedral fullerenes have been proposed for a number of technological uses, for example, as a nanoscale switch, memory bit and as qubits for quantum computation. For these technology applications, it is important to know the ease with which the endohedral atom can be manipulated using an applied electric field. We find that the Buckminsterfullerene (C60) acts effectively as a smallFaradaycage, with only 25% of the field penetrating the interior of the molecule. Thus influencing the atom is difficult, but as a qubit the endohedral atom should be well shielded from environmental electrical noise. We also predict how the field penetration should increase with the fullerene radius."http://titus.phy.qub.ac.uk/group/Paul/publications/2004/Delaney_Greer... This might be because carbon is not normally a good conductor, much less the "perfect conductor" required for theFaradaycagedo to complete screening. Ideally, though aFaradaycagedoes complete screening regardless of the size. BTW, here's a nice animation of how the electric field lines bend around a conductingcage: Isolated Cylinderhttp://socrates.berkeley.edu/~fajans/Teaching/cartoons/Shielding/Test... The applet showing this for some reason does not show up on my computer using the Firefox browser, but shows up well using IE. How well the nested buckyballs could do screening would have to be determined by experiment. Also, carbon can become superconducting at very low temperatures. I mentioned that you would get better screening using metal buckyballs. I don't know if this has been done but I found a report showing that it should be possible with boron (also not a metal): Bucky's brother -- The boron buckyball makes its debut. Published: 12:29 EST, April 23, 2007http://www.physorg.com/news96550194.html Another consideration for space based applications is the mass of thecagecompared with the mass of the charged particle it contained. If the particle was uranium, with an atomic mass of 238, contained in a single layer carbon fullerene C60, the ratio of the container to the ions would be 60x12 = 720 to 238, or 3 to 1. Ideal would be a light metal that could be formed into a single atomic layercage. Lithium for example is classified as an alkali metal with a conductivity more than 100 times that of carbon: Lithium.http://www.chemicool.com/elements/lithium.html Carbon.http://www.chemicool.com/elements/carbon.html Bob Clark Notably boron becomes a superconductor at ever increasing temperatures according to pressure at the megabar pressure range: Newsgroups: sci.materials, sci.astro, sci.physics, sci.energy, sci.chem From: Robert Clark Date: Thu, 22 Nov 2007 15:29:03 -0800 (PST) Local: Thurs, Nov 22 2007 6:29 pm Subject: A route to room-temperature superconductivity? http://groups.google.com/group/sci.m...6b68f22afdc0c/ Bob Clark |
#27
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Startling amounts of stored energy in fully ionized plasmas.
Thanks for the interesting topic. Endofullerene is quite an exotic molecule and you have a lot of room to fiddle with it. In this context it really looks promising. Iam really excited about fast development of these materials.. For example check this one out: http://mstnano.com/products/endofullerene/
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