Startling amounts of stored energy in fully ionized plasmas.
Robert Clark
drives I was surprised by the total amounts of energy that would be
required to *fully* ionize the gas. This amount of energy is quite
large, actually huge, and so for actual ion drives the gas is only
minimally ionized.
Some examples of the amount of ionization energy energy can be found
here:
Ionization energies of the elements.
http://en.wikipedia.org/wiki/Ionization_energies_of_the_elements
You see for hydrogen it's 1312 kilojoules per mole. Since the atomic
weight of hydrogen is 1, this is 1,312,000 joules per gram or 1.3
billion joules per kilo. Note that this amount of energy that needs
to be added to ionize the gas will conversely be released when the
electrons are recombined with the ionized gas. Then this is several
times higher than the maximum energy density of chemical reactions on
a per weight basis such as by chemically oxidizing neutral hydrogen:
Energy density in energy storage and in fuel.
http://en.wikipedia.org/wiki/Energy_density#Energy_density_in_energy_storage_and_in_fuel
Other elements can produce even higher amounts. By and large, the
energy density gets higher for the heavier elements. For instance you
can find the total for copper by adding up the amounts given on the
"Ionization energies of the elements" page. You get 4,345,619.4 in kJ/
mol. Then since the atomic weight of copper is 64, this amounts to 68
billion joules per kilo.
On the "Energy density in energy storage and in fuel" page, there is
a huge gap in energy density between the chemical reactions to the
nuclear reactions. Then these "electron recombination" reactions, if
you will, would provide an intermediate level in energy storage
density.
However, for getting these amounts note that the element has to be in
gas form since the energy required to release the electrons from orbit
is different for solids, called the "work function", usually smaller.
So the released amount of energy on recombination would also be
smaller. Then for some elements such as metals you would also have to
supply high heat to get the element in gas form. Then this energy
storage method would probably be better in heavy gases, such as
xenon.
The ionization energy of xenon is incomplete on the "Ionization
energies of the elements" page. A more complete list can be found on
the page:
NIST Atomic Spectra Database Levels Form.
http://physics.nist.gov/PhysRefData/ASD/levels_form.html
by typing in for example Xe 53 to get the last (54th) electron
ionization energy. However, not every ionization level for xenon is
given on this page either. After a web search, I found the total
amount of energy required to fully ionize xenon is about 200 keV.
Since 1 eV is about 100 kJ/mol , this is about, 2 x 10^10 J/mol. Since
the atomic weight of xenon is 130 this comes to 154 million joules per
gram, 154 billion joules per kilo.
There are table top instruments available for producing and studying
these highly ionized plasmas:
Highly Ionized Plasmas.
http://www.llnl.gov/str/Schneider.html
The problem of course is storing them for long periods. If they
contact the walls of a container then they will lose their ionization.
Some possibilities would be to use Penning or Paul traps used to store
non neutral plasmas for fusion research:
Penning trap.
http://en.wikipedia.org/wiki/Penning_trap
Quadrupole ion trap (Paul trap).
http://en.wikipedia.org/wiki/Paul_trap
The amount of energy available from the ions is so high it's possible
we could siphon off a small portion of them to use their energy to
maintain the containment of the rest.
The Penning trap uses in part magnetic fields and there is a limit to
the number of particles such a trap will contain called the Brillouin
limit depending on the strength of the magnetic field. Since there is
a limit to the strength of *stable* magnetic fields that so far can be
maintained in the range of perhaps 50 T, this puts a severe limit on
the density of fully ionized particles that could be contained.
However, some researchers claim the Brillouin limit can be exceeded:
Confinement Of Pure Ion Plasma In A Cylindrical Current Sheet.
http://www.pppl.gov/pub_report//2000/PPPL-3403.pdf
Even the density achieved here though is still quite low at 4×10^14
particles per cm^3. This is at nanogram levels per cubic centimeter,
milligrams per cubic meter.
Since the Paul trap does not use magnetic fields it is unclear to me
if there is a limit to how many particles it can contain.
There would need to be quite a bit more research on how to contain
these plasmas at high densities if this is to be an energy storage
method in common use on Earth. However, it is possible that they could
be used to provide energy for space missions in deep space where
volume is not as big a concern, only mass. For instance, even at
milligrams per cubic meter this could provide kilograms of storage if
kept within a volume a hundred meters wide. For ion drives that
typically use fuel at rates of milligrams per second this could
provide fuel and the energy to power the drive over several days.
cf.:
From: Robert Clark <rgregorycl...@yahoo.com>
Newsgroups: sci.space.policy, sci.astro, sci.physics,
sci.physics.relativity, sci.physics.fusion
Date: Thu, 20 Sep 2007 13:47:28 -0700
Local: Thurs, Sep 20 2007 4:47 pm
Subject: Stored ionized gas for ion drives.
http://groups.google.com/group/sci.space.policy/msg/cb4c75eb5630f41d
Bob Clark
Craig Markwardt
Robert Clark <rgrego...@yahoo.com> writes:
> In researching the amount of energy required to ionize gas for ion
> drives I was surprised by the total amounts of energy that would be
> required to *fully* ionize the gas. This amount of energy is quite
> large, actually huge, and so for actual ion drives the gas is only
> minimally ionized.
> by typing in for example Xe 53 to get the last (54th) electron
> ionization energy. However, not every ionization level for xenon is
> given on this page either. After a web search, I found the total
> amount of energy required to fully ionize xenon is about 200 keV.
> Since 1 eV is about 100 kJ/mol , this is about, 2 x 10^10 J/mol. Since
> the atomic weight of xenon is 130 this comes to 154 million joules per
> gram, 154 billion joules per kilo.
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.
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.
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...
CM
Robert Clark
<craigm...@REMOVEcow.physics.wisc.edu> wrote:
Thanks for the informative response. Quite key here is that these are
*non-neutral* plasmas. That means the charges are all of the same
sign, all positive or all negative. In your formula you gave note this
would result in the Bremsstrahlung emissivity being zero since one of
the types of charge would be absent.
There has been alot of research on non neutral plasmas showing they
can be stored in magnetic/electrostatic traps for several days:
What is a nonneutral plasma?
http://www-physics.ucsd.edu/~dhdpla/nnp.html
Bob Clark
malibu
Interesting.
Each galaxy emits plasma from its center at right-angles to
its disc (being 'blown off its accretion disc' NOT). The central
vortex separates infalling neutrons into negative and positive plasmas
and blows them out in opposite directions.
One kind of non-neutral plasma will be going out
one way, and the other will go out the other way.
The two will eventually re-combine into new stars.
John
Craig Markwardt
Huh? First of all, that equation assumed a Boltzmann equilibrium,
which would not be the case if one conveniently "removed" *all*
electrons.
But is that plausible? No. First, fully ionizing a species like
Xenon would still required effectively heating the atoms to
temperatures of kB T ~ 100 keV. Before one could somehow magically
transfer (just) the ions to the storage tank, the energy would be lost
by thermal bremsstrahlung radiation very quickly. Second, a plasma
made up of positive ions *still* radiates by thermal bremstrahlung, so
one can't just pretend the effect is zero.
However, neither of these issues is the real fatal flaw...
> There has been alot of research on non neutral plasmas showing they
> can be stored in magnetic/electrostatic traps for several days:
Really? Have you considered how much Coulomb energy is required to
separate the charges even by 1 cm? For even 1 cubic cm of the Xenon
you mentioned, the Coulomb energy is tens of thousands of times larger
than the ionization energy density, at voltages of many tens of
megaVolts. In other words, the "trap" would simply be crushed due to
Coulomb forces. A lab setup with a few thousand ions is far different
from your scenario, which is totally implausible.
CM
Robert Clark
You are right it would take quite a bit of energy to create the fully
ionized plasmas and quite alot of energy to separate the electrons.
This is clearly not a means of getting "free" energy such as nuclear,
solar, or fossil fuels. It is only a way of storing it.
According to the web site I linked, the positive ions in their traps
could be stored as long as they want if the magnetic/electrostatic
containment fields are sufficiently uniform:
What is a nonneutral plasma?
"Confinement. Nonneutral plasmas can be confined for long periods of
time using only static electric and magnetic fields. One such
configuration is called a Penning Trap, after the inventor F. M.
Penning. The trap consists of a several cylindrically symmetric
electrodes and a uniform magnetic field applied along the axis of the
trap (see diagram below).
"Axial confinement (for a positive plasma) is provided by positive
voltages applied to the end electrodes, which creates an axial
potential well. Radial confinement is provided by the magnetic field.
The plasma rotates, and the resulting v x B force is radially inward,
balancing the outward electric force caused by the unneutralized
collection of charges.
"If the Penning trap had perfect cylindrical symmetry, the plasma
would be confined forever. However, since there are always small
irregularities in the trap fields that break the cylindrical symmetry,
these irregularities drag on the plasma, slowing down its rotation and
decreasing the confining v x B force. This results in a loss of the
plasma, but these irregularities can be made so small that the plasma
can be confined for days in actual experiments. In addition, a new
technique (called the 'rotating wall') has recently been invented by
our group; it allows us to spin up the plasma, keeping it spinning and
confined in the trap for as long as we wish."
http://www-physics.ucsd.edu/~dhdpla/nnp.html#conf
Since the purpose of much of the research on non neutral plasmas is
toward fusion power, these research teams clearly believe their
containment methods can be ramped up to large amounts of non neutral
plasma.
Here's a report on the containment of a million Beryllium ions for
over 30 minutes:
Phase-Locked Rotation of Crystallized Non-neutral Plasmas by Rotating
Electric Fields.
X.-P. Huang, J. J. Bollinger, T. B. Mitchell, and Wayne M. Itano Time
& Frequency Division, National Institute of Standards and Technology,
325 Broadway, Boulder, Colorado 80303
(Received 29 August 1997)
"We report the precise control of the rotation frequency of strongly
coupled non-neutral plasmas by rotating electric fields. These plasmas
of up to 10^6 9Be1 ions are trapped in a Penning trap and laser cooled
into crystallized structures which undergo a rigid-body rotation.
Bragg diffraction shows that the crystalline lattice can be stable for
longer than 30 min (,108 rotations), and that the plasma rotation can
be phase locked to the applied field without any slip. These
corotating plasmas are in a novel global thermal equilibrium whose
asymmetric surface shape (triaxial ellipsoid) has been measured."
http://tf.nist.gov/general/pdf/1215.pdf
And this reports on containment of a billion ions for a period of
weeks:
Confinement and manipulation of non-neutral plasmas using rotating
wall electric fields.
E. M. Hollmann, F. Anderegg, and C. F. Driscoll.
Physics Department and Institute for Pure and Applied Physical
Sciences, University of California at San Diego, La Jolla, California
92093-0319
(Received 24 February 2000; accepted 17 April 2000)
"A 'rotating wall' perturbation technique enables confinement of up to
3×10^9 electrons or 10^9 ions in Penning-Malmberg traps for periods of
weeks. These rotating wall electric fields transfer torque to the
particles by exciting Trivelpiece-Gould plasma modes with kz[not-
equal]0 and mtheta = 1 or 2. Modes that rotate faster than the plasma
column provide a positive torque that counteracts the background
drags, resulting in radial plasma compression or steady-state
confinement in near-thermal equilibrium states. Conversely, modes that
rotate slower than the plasma provide a negative torque, and enhanced
plasma expansion is observed. The observed Trivelpiece-Gould mode
frequencies are well predicted by linear, infinite-length, guiding-
center theory."
http://link.aip.org/link/?PHP/7/2776/1 [abstract only]
Bob Clark
Craig Markwardt
Robert Clark <rgrego...@yahoo.com> writes:
...
You seem to be missing the point. If it takes many thousand times as
much energy to separate the charges as it does to ionize them, then
you've built a 99.999% capacitor + 0.001% ion storage device. But
there are much safer and straightforward ways to build a capacitor, so
why bother with the ionization part at all?
CM
Robert Clark
<craigm...@REMOVEcow.physics.wisc.edu> wrote:
> ....
> ...
>
> You seem to be missing the point. If it takes many thousand times as
> much energy to separate the charges as it does to ionize them, then
> you've built a 99.999% capacitor + 0.001% ion storage device. But
> there are much safer and straightforward ways to build a capacitor, so
> why bother with the ionization part at all?
>
> CM
No capacitor or battery or any energy storage method short of
nuclear power offers anywhere near 154 billion joules per kilogram
energy storage.
See the list of energy densities here:
Energy density in energy storage and in fuel.
http://en.wikipedia.org/wiki/Energy_density#Energy_density_in_energy_storage_and_in_fuel
Bob Clark
Craig Markwardt
Robert Clark <rgrego...@yahoo.com> writes:
> On Oct 13, 11:15 pm, Craig Markwardt
> <craigm...@REMOVEcow.physics.wisc.edu> wrote:
> > ....
> > ...
> >
> > You seem to be missing the point. If it takes many thousand times as
> > much energy to separate the charges as it does to ionize them, then
> > you've built a 99.999% capacitor + 0.001% ion storage device. But
> > there are much safer and straightforward ways to build a capacitor, so
> > why bother with the ionization part at all?
> >
> > CM
>
>
> No capacitor or battery or any energy storage method short of
> nuclear power offers anywhere near 154 billion joules per kilogram
> energy storage.
...
OK, and given that it takes tens of thousands of times *more* energy
density than the ionization energy density in order to overcome the
Coulomb forces, how exactly do you plan on building your storage
device? It seems you've just proved my point.
CM
Robert Clark
> In researching the amount of energy required to ionize gas for ion
> drives I was surprised by the total amounts of energy that would be
> required to *fully* ionize the gas. This amount of energy is quite
> large, actually huge, and so for actual ion drives the gas is only
> minimally ionized.
> Some examples of the amount of ionization energy energy can be found
> here:
>
>
> You see for hydrogen it's 1312 kilojoules per mole. Since the atomic
> weight of hydrogen is 1, this is 1,312,000 joules per gram or 1.3
> billion joules per kilo. Note that this amount of energy that needs
> to be added to ionize the gas will conversely be released when the
> electrons are recombined with the ionized gas. Then this is several
> times higher than the maximum energy density of chemical reactions on
> a per weight basis such as by chemically oxidizing neutral hydrogen:
>
>
> Other elements can produce even higher amounts. By and large, the
> energy density gets higher for the heavier elements. For instance you
> can find the total for copper by adding up the amounts given on the
> "Ionization energies of the elements" page. You get 4,345,619.4 in kJ/
> mol. Then since the atomic weight of copper is 64, this amounts to 68
> billion joules per kilo.
> On the "Energy density in energy storage and in fuel" page, there is
> a huge gap in energy density between the chemical reactions to the
> nuclear reactions. Then these "electron recombination" reactions, if
> you will, would provide an intermediate level in energy storage
> density.
> However, for getting these amounts note that the element has to be in
> gas form since the energy required to release the electrons from orbit
> is different for solids, called the "work function", usually smaller.
> So the released amount of energy on recombination would also be
> smaller. Then for some elements such as metals you would also have to
> supply high heat to get the element in gas form. Then this energy
> storage method would probably be better in heavy gases, such as
> xenon.
> The ionization energy of xenon is incomplete on the "Ionization
> energies of the elements" page. A more complete list can be found on
> the page:
>
>
> by typing in for example Xe 53 to get the last (54th) electron
> ionization energy. However, not every ionization level for xenon is
> given on this page either. After a web search, I found the total
> amount of energy required to fully ionize xenon is about 200 keV.
> Since 1 eV is about 100 kJ/mol , this is about, 2 x 10^10 J/mol. Since
> the atomic weight of xenon is 130 this comes to 154 million joules per
> gram, 154 billion joules per kilo.
This report gives the total ionization energy for uranium as 762.9
keV:
Electron Emission Following the Interaction of Slow Highly Charged
Ions with Solids.
http://www.osti.gov/bridge/servlets/purl/301182-E18IT0/webviewable/301182.pdf
Since 1 eV is about 100 kJ/mol and the atomic weight of uranium is
238, this amounts to 320 billion joules per kilogram. Other elements
with high total ionization energies are given in Fig. 1 in this
report.
To put this in perspective, the energy density of hydrogen burned
with oxygen is 140 million joules per kilo of hydrogen. So the
electron recombination reaction of uranium results in more than 2000
times the energy per kilogram.
The space shuttle external tank contains about 100,000 kg of hydrogen
and 600,000 kg of oxygen. Then the energy content here would be
equivalent to only 50 kg of fully ionized uranium. (Note this is *not*
a nuclear reaction.) And the oxygen also would not be required.
Note this is only in regards to the energy content. It does not
consider how the thrust would be generated.
Bob Clark
Paul F. Dietz
time using only static electric and magnetic fields. One such
configuration is called a Penning Trap, after the inventor F. M.
Penning. The trap consists of a several cylindrically symmetric
electrodes and a uniform magnetic field applied along the axis of the
trap (see diagram below).
A Penning trap is limited in the number of ions it can store
due to the self-repulsion of the ions. If one does the analysis,
it turns out the energy stored in the magnetic field of the
trap must be at least as large as the rest energy of the stored
ions.
So, if you are storing highly charged ordinary ions, the
ionization energy of those ions is a small fraction of the energy
of the trap's magnets, and adds little to the stored energy
of the system.
Electrostatic quadrupole (Paul) traps may be able to evade
this limit; I'm not clear on that.
Paul
Craig Markwardt
Robert Clark <rgrego...@yahoo.com> writes:
> On Oct 11, 9:10 pm, Robert Clark <rgregorycl...@yahoo.com> wrote:
> > In researching the amount of energy required to ionize gas for ion
> > drives I was surprised by the total amounts of energy that would be
> > required to *fully* ionize the gas. This amount of energy is quite
> > large, actually huge, and so for actual ion drives the gas is only
> > minimally ionized.
...
> This report gives the total ionization energy for uranium as 762.9
> keV:
Changing the atomic species does not change the fact that it would
take far more energy density to maintain the trap than could ever be
stored in the ionization energy.
CM
Robert Clark
Hmm. That's a very interesting point. The Brillouin limit does place
a limit on the number of ions stored based on the square of the
magnetic field magnitude and the rest energy of the particles.
However, a large portion of the research on these magnetically
confined non neutral plasmas is due to fusion research. If there was
such a limit on the energy content of the ions that would also mean
the possible fusion energy would be limited by the same amount.
Perhaps its because the magnetic field term in the Brillouin limit is
B^2, which is only the energy *density* of the magnetic field? I'll
ask about that.
Bob Clark
Robert Clark
Yes, by the Brillouin limit the total rest energy of the particles
must be less than the magnetic field energy, *under the specialized
conditions for which the Brillouin limit holds*. Such traps operating
under this limit are still useful for fusion research since you can
inject more particles to continually get more fusion energy out while
the magnetic field remains the same.
I am informed that there is also a limit to the number of particles
you can contain using electrostatic fields such as by the Paul trap,
but I don't know yet if this also results in the rest energy of the
particles being less than the energy of the containing electric
fields.
However, this report shows that the Brillouin limit on magnetic field
containment can be exceeded for non-uniform magnetic fields:
Confinement Of Pure Ion Plasma In A Cylindrical Current Sheet.
Stephen F. Paul, Edward H. Chao, Ronald C. Davidson, Cynthia K.
Phillips.
Plasma Physics Laboratory
Princeton University, Princeton, New Jersey 08543
"Abstract. A novel method for containing a pure ion plasma at
thermonuclear densities and temperatures has been modeled. The method
combines the confinement properties of a Penning-Malmberg trap and
some aspects of the magnetic filed geometry of a pulsed theta-pinch. A
conventional Penning trap can confine a uniform-density plasma of
about 5x 10^11/cm³.with a 30-Tesla magnetic field. However, if the
axial field is ramped, a much higher local ion density can be
obtained. Starting with a 10^7/ cm³.
trapped deuterium plasma in a conventional Penning-Malmberg trap at
the Brillouin limit (B = 0.6 Tesla), the field is ramped to 30 Tesla.
Because the plasma is comprised of particles of only one sign of
charge, transport losses are very low, i.e., the conductivity is high.
As a result, the ramped field does not penetrate the plasma and a
diamagnetic surface current is generated, with the ions being
accelerated to relativistic velocities.
To counteract the inward j x B forces from this induced current,
additional ions are injected into the plasma along the axis to
increase the density (and mutual electrostatic repulsion) of the
target plasma. In the absence of the higher magnetic field in the
center, the injected ions drift outward until a balance is established
between the outward
driving forces (centrifugal, electrostatic, pressure gradient) and the
inward j x B force.
An equilibrium calculation using a relativistic, 1-D, cold-fluid model
shows that a plasma can be trapped in a hollow, 49-cm diameter, 0.2-cm
thick cylinder with a density exceeding 4x10^14 / cm³.."
http://www.pppl.gov/pub_report//2000/PPPL-3403.pdf
This results in a particle density 1,000 times the Brillouin limit.
It is possible that an optimized choice of the magnetic field geometry
would result in it also requiring less energy to constrain the ions
than what you can get out as energy in the electron recombination
reactions.
But such non-symmetric magnetic field containment methods already
require far less containment energy than what you can get out by the
matter-energy conversion of the stored particles. Then why not use
such ion containment methods to store the full amount of energy in
matter to energy conversion!
The page with the list of energy density storage methods shows at the
top of the list that this is a tremendous amount of energy:
Energy density in energy storage and in fuel.
http://en.wikipedia.org/wiki/Energy_density#Energy_density_in_energy_storage_and_in_fuel
There is already ongoing research with the research teams storing non
neutral plasmas on storing antimatter versions as well, such as
antiprotons and positrons. Then you could allow these stored
antimatter particles to contact normal matter to get the full energy
released as contained in their rest energy.
This is probably closer to fruition with the positron traps since it
so much easier to produce and trap positrons in large numbers than
antiprotons. A problem though is that the energy released by combining
electrons and positrons releases the energy as .5 MeV gamma rays. Such
gamma rays are highly penetrating. So methods would have to be used to
capture, absorb these gamma rays so they can be converted to useful
forms of energy, electrical, heat, etc.
Some possibilities might come from methods used by gamma ray
detecting satellites to detect gamma rays from astronomical sources:
Gamma-ray Detectors.
http://www.airynothing.com/high_energy_tutorial/detection/detection05.html
A recently proposed method for gamma ray detection might also be
useful in this regard:
Gamma Ray Fresnel lenses - why not?
http://arxiv.org/abs/astro-ph/0602074
The methods described in the "Confinement Of Pure Ion Plasma In A
Cylindrical Current Sheet" would result in milligrams per cubic meter
of storage based on containment fields of 30 Tesla, about the highest
for stable fields in use now.
However, it is quite likely that stable fields of higher strength can
be produced with advanced materials available now. As described in
this report the limits on the strength of stable magnetic fields are
due to the magnetic forces on the conducting elements that tend to
tear them apart:
Magnetic Radiation Shielding: An Idea Whose Time Has Returned?
Geoffrey A. Landis
"The limit to the mass required to produce a magnetic field is set by
the tensile strength of materials required to withstand the magnetic
self-force on the conductors [8]. For the min-imum structure, all the
structural elements are in tension, and from the virial theorem, the
mass required to withstand magnetic force can be estimated as [9]:
M = (rho/S) (B^2 V)/(2 mu) (1)
where rho is the density of the structural material, S is the tensile
strength, B the magnetic field, V the characteristic volume of the
field, and mu the permeability of vacuum."
http://www.islandone.org/Settlements/MagShield.html
You see the strength/density ratio of the material goes by the square
of the magnetic field strength. The conducting wire commonly used for
producing the electromagnets is made of copper because of its high
conductivity and current carrying capacity. This page gives the
tensile strength of copper as 220 MPa at a density of 8.92 g/cm³.
The highest measured strength of carbon nanotubes has been 160 GPa at
a density of 1.3 g/cm³. This is an increase of the strength to
density ratio over copper of about 5,000.
Then conceivably with this stronger material we could get higher
magnetic fields strengths by a factor of the square root of this, 70;
so to a magnetic field strength of 70 x 30 T = 2100 T.
But the density of the confined ions is actually by the square of the
magnetic field, so it would be increased by the full factor of 5,000.
Then we could get kilogram storage of the ions within a volume less
than 10 meters on a side.
The nanotubes are only available so far at centimeter lengths. Still
it would be interesting to find out on tests with small fields if
their use would allow magnetic field strengths in the thousand tesla
range. Also, it may be possible to get large amounts of contained ions
by using very many of the short nanotubes to produce very many
separate, small containment fields.
For the nanotubes to be used for this purpose they would have to
carry large amounts of current to generate the electromagnets. It has
been shown experimentally that they can carry thousands of times the
current of copper:
Reliability and current carrying capacity of carbon nanotubes.
APPLIED PHYSICS LETTERS, VOLUME 79, NUMBER 8, 20 AUGUST 2001.
"From the experimental results described in this letter we
can conclude that multiwalled carbon nanotubes can carry
high current densities up to 10^9-10^10 A/cm2 and remain
stable for extended periods of time at higher temperature in
air. Furthermore, they conduct current without any measurable
change in their resistance or morphology, indicating that
the sp2 bonds that are dominant in carbon nanotubes provide
much higher stability against electromigration than small
metallic structures."
http://www.rpi.edu/~ajayan/locker/pdfs/reliability.pdf
We can estimate the strength of the magnetic field we can obtain from
a given current flow and wire size from the formula B = 2(10^-7)I/r,
for B the magnetic field in Tesla, I the current in amps, and r the
distance from the center of the wire in meters, as described here:
Magnetic Field of Current.
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html#c2
For a 100 micron thick wire composed of carbon nanotube material,
using a 10^10 A/cm2 current capacity, we could get 10^6 A of current
through. Then 100 microns away from the center the magnetic field
would be 2,000 T.
Experiments at very high magnetic fields are very important for
theoretical studies. It is likely the nanotubes could withstand the
high stresses induced by the magnetic fields at even higher strengths
than 2100 T for short times, especially for nanotubes chosen to be low
in defects to have the highest strength. Then carbon nanotubes may be
the ideal material to use for producing ultra high magnetic fields for
theoretical work.
Bob Clark
Craig Markwardt
The magnetic field only confines the ions in one direction. You
should probably estimate the magnitude of the *electric* field
required. How does the energy in that field compare to the ionization
energy?
CM
Robert Clark
> On Oct 11, 9:10 pm, Robert Clark <rgregorycl...@yahoo.com> wrote:
>
>
>
> > In researching the amount of energy required to ionize gas for ion
> > drives I was surprised by the total amounts of energy that would be
> > required to *fully* ionize the gas. This amount of energy is quite
> > large, actually huge, and so for actual ion drives the gas is only
> > minimally ionized.
>
> Since 1 eV is about 100 kJ/mol and the atomic weight of uranium is
> 238, this amounts to 320 billion joules per kilogram. Other elements
> with high total ionization energies are given in Fig. 1 in this
> report.
> To put this in perspective, the energy density of hydrogen burned
> with oxygen is 140 million joules per kilo of hydrogen. So the
> electron recombination reaction of uranium results in more than 2000
> times the energy per kilogram.
> The space shuttle external tank contains about 100,000 kg of hydrogen
> and 600,000 kg of oxygen. Then the energy content here would be
> equivalent to only 50 kg of fully ionized uranium. (Note this is *not*
> a nuclear reaction.) And the oxygen also would not be required.
> Note this is only in regards to the energy content. It does not
> consider how the thrust would be generated.
>
> Bob Clark
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
here:
Newsgroups: sci.physics, sci.physics.relativity
From: rgregorycl...@yahoo.com
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.physics/browse_thread/thread/aff5212e4978e112/3b2217b72369034
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 recombination
energy in the case of ion storage or the matter-antimatter conversion
energy in the case of positron storage.
Bob Clark
Robert Clark
> ...
> 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
> here:
>
> Newsgroups: sci.physics, sci.physics.relativity
> From: rgregorycl...@yahoo.com
> Date: 7 Jul 2005 10:42:54 -0700
> Local: Thurs, Jul 7 2005 1:42 pm
>
> One suggested solution was the 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 recombination
> energy in the case of ion storage or the matter-antimatter conversion
> energy in the case of positron storage.
>
Another possibility would be use the relativistic effect of magnetic
and electric fields being interchanged at high relativistic
velocities.
Here is one online report that explains this effect of special
relativity:
The simplest, and the full derivation of Magnetism as a Relativistic
side effect of ElectroStatics.
http://www.chip-architect.com/physics/Magnetism_from_ElectroStatics_and_SR.pdf
Then we could cause the contained ions, electrons, or positrons to
rotate within a magnetic field at relativistic velocities. The idea is
that the relativistic charged particles would regard the constraining
magnetic field as an intense electric field and thus we would be able
to obtain denser storage.
In regards to this possibility I saw this report that suggests
relativistic speeds can cause the Coulomb self-repulsion to approach
zero, with a proviso:
Catalyzing Fusion with Relativistic Electrons.
Authors: Hanno Essen
http://arxiv.org/abs/physics/0607138
The proviso is that the charged particles have to be at high speeds
relative to each other. We would have to find a way of achieving this
while the particles remained in a constrained volume.
Another possibility is that the containing magnetic field might
regard the charged particles as having a smaller self-repulsion if
they are moving at high speed with respect to the magnetic field. Then
a smaller magnetic field might suffice to contain them.
Because of the high energy required to accelerate particles to
relativistic speeds, these methods might be best tried on electrons
and positrons rather than on ions.
Bob Clark
Androcles
"Robert Clark" <rgrego...@yahoo.com> wrote in message
news:1193523790.7...@57g2000hsv.googlegroups.com...
Sorry to burst your bubble but you are dreaming.
1) To ionize, you need a lot of voltage as you've already noted.
http://www.ilankelman.org/disasterdeaths/lightning.jpg
2) Vacuum is far from being an insulator where high voltages are
concerned.
http://www.astronomycafe.net/qadir/ask/TVtube.gif
3) Relativity is built upon "proof because I say so".
Wackypedia has these proofs:
1 Direct proof
2 Proof by induction
3 Proof by transposition
4 Proof by contradiction
5 Proof by construction
6 Proof by exhaustion
7 Probabilistic proof
8 Combinatorial proof
9 Nonconstructive proof
10 Elementary proof
Missing are these, even in wackypedia:
11 Proof by "everybody knows".
12 Proof by "because I say so".
'we establish by definition that the "time" required by
light to travel from A to B equals the "time" it requires
to travel from B to A' because I SAY SO and you have to
agree because I'm the great genius, STOOOPID, don't you
dare question it. -- Rabbi Albert Einstein
http://www.androcles01.pwp.blueyonder.co.uk/Smart/tAB=tBA.gif
Robert Clark
> On Oct 14, 2:11 pm, Robert Clark <rgregorycl...@yahoo.com> wrote:
>
>
>
>
>
> > On Oct 11, 9:10 pm, Robert Clark <rgregorycl...@yahoo.com> wrote:
>
> > > drives I was surprised by the total amounts ofenergythat would be
> > > required to *fully* ionize the gas. This amount ofenergyis quite
> > > large, actually huge, and so for actual ion drives the gas is only
> > > minimally ionized.
> > > here:
>
> > > Ionization energies of the elements.http://en.wikipedia.org/wiki/Ionization_energies_of_the_elements
>
> > > You see for hydrogen it's 1312 kilojoules per mole. Since the atomic
> > > weight of hydrogen is 1, this is 1,312,000 joules per gram or 1.3
> > > to be added to ionize the gas will conversely be released when the
> > > electrons are recombined with the ionized gas. Then this is several
> > > a per weight basis such as by chemically oxidizing neutral hydrogen:
>
>
> > > Other elements can produce even higher amounts. By and large, the
> > > can find the total for copper by adding up the amounts given on the
> > > "Ionization energies of the elements" page. You get 4,345,619.4 in kJ/
> > > mol. Then since the atomic weight of copper is 64, this amounts to 68
> > > billion joules per kilo.
> > > a huge gap inenergydensity between the chemical reactions to the
> > > nuclear reactions. Then these "electron recombination" reactions, if
> > > you will, would provide an intermediate level inenergystorage
> > > density.
> > > However, for getting these amounts note that the element has to be in
> > > is different for solids, called the "work function", usually smaller.
> > > smaller. Then for some elements such as metals you would also have to
> > > supply high heat to get the element in gas form. Then thisenergy
> > > storage method would probably be better in heavy gases, such as
> > > xenon.
> > > energies of the elements" page. A more complete list can be found on
> > > the page:
>
> > > NIST Atomic Spectra Database Levels Form.http://physics.nist.gov/PhysRefData/ASD/levels_form.html
>
> > > by typing in for example Xe 53 to get the last (54th) electron
> > > given on this page either. After a web search, I found the total
> > > Since 1 eV is about 100 kJ/mol , this is about, 2 x 10^10 J/mol. Since
> > > the atomic weight of xenon is 130 this comes to 154 million joules per
> > > gram, 154 billion joules per kilo.
> > > ...
>
> > keV:
>
> > Electron Emission Following the Interaction of Slow Highly Charged
> > Ions with Solids.http://www.osti.gov/bridge/servlets/purl/301182-E18IT0/webviewable/30...
>
> > Since 1 eV is about 100 kJ/mol and the atomic weight of uranium is
> > 238, this amounts to 320 billion joules per kilogram. Other elements
> > with high total ionization energies are given in Fig. 1 in this
> > report.
> > with oxygen is 140 million joules per kilo of hydrogen. So the
> > electron recombination reaction of uranium results in more than 2000
> > The space shuttle external tank contains about 100,000 kg of hydrogen
> > equivalent to only 50 kg of fully ionized uranium. (Note this is *not*
> > a nuclear reaction.) And the oxygen also would not be required.
> > consider how the thrust would be generated.
>
> > Bob Clark
>
> 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
> here:
>
> Newsgroups: sci.physics, sci.physics.relativity
> From: rgregorycl...@yahoo.com
> Date: 7 Jul 2005 10:42:54 -0700
> Local: Thurs, Jul 7 2005 1:42 pm
>
> One suggested solution was the 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 recombination energy in the case of ion storage or the matter-antimatter conversion energy in 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
Robert Clark
> >energyin the case of positron storage.
>
> Another possibility would be use the relativistic effect of magnetic
> and electric fields being interchanged at high relativistic
> velocities.
> Here is one online report that explains this effect of special
> relativity:
>
> The simplest, and the full derivation of Magnetism as a Relativistic
>
> Then we could cause the contained ions, electrons, or positrons to
> rotate within a magnetic field at relativistic velocities. The idea is
> that the relativistic charged particles would regard the constraining
> magnetic field as an intense electric field and thus we would be able
> to obtain denser storage.
> In regards to this possibility I saw this report that suggests
> relativistic speeds can cause the Coulomb self-repulsion to approach
> zero, with a proviso:
>
> Catalyzing Fusion with Relativistic Electrons.
>
> The proviso is that the charged particles have to be at high speeds
> relative to each other. We would have to find a way of achieving this
> while the particles remained in a constrained volume.
> Another possibility is that the containing magnetic field might
> regard the charged particles as having a smaller self-repulsion if
> they are moving at high speed with respect to the magnetic field. Then
> a smaller magnetic field might suffice to contain them.
> relativistic speeds, these methods might be best tried on electrons
> and positrons rather than on ions.
>
> Bob Clark
There are some more variations on this possibility. In particle
physics there is a phenomenon at high relativistic speeds called
Moeller scattering where an electron coming very close to a high Z
nucleus will actually feel the Coulomb force being reversed to being
repulsive. Does this work for same charge particles coming close to
each at high relativistic speeds where the Coulomb force is reversed
to being attractive?
Also, in superconductivity there is the Meissner effect where a
superconductor screens out a magnetic field as well as keeping one
inside. Then when the charged particles are at high relativistic
speeds with respect to the superconductor, the particles electric
field will be felt by the superconductor to be a magnetic field and it
will be prevented from leaving the superconductor. Then this will act
as another method of screening the electric field between the charges
if each charge of groups of charges is surrounded by its own
superconductor.
Bob Clark
Robert Clark
> ...
>
> > 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/Paul/publications/2004/Delaney_Greer_C60_as_a_Faraday_cage_APL_84_2004_431.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/How_metallic_are_metal_nanotubes_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
Autymn D. C.
<craigm...@REMOVEcow.physics.wisc.edu> 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
Autymn D. C.
> 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?
Robert Clark
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_C60_as_a_Faraday_cage_APL_84_2004_431.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/Teaching/cartoons/Shielding/TestChargeShielding_files/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
Robert Clark
> On Nov 21, 8:58 pm, "Autymn D. C." <lysde...@sbcglobal.net> 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
>
> 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:
>
>
> 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.
>
> 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/2006/05/060516075733.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
Robert Clark
>
>
>
> > On Nov 20, 11:19 pm, Robert Clark <rgregorycl...@yahoo.com> 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
>
> This might be because carbon is not normally a good conductor, much
> 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:
>
>
> 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.
>
> 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
> metal with a conductivity more than 100 times that of carbon:
>
>
> 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 <rgregorycl...@yahoo.com>
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.materials/browse_thread/thread/8a76b68f22afdc0c/
Bob Clark
