Bussard ICF EXL engines

Does anyone know how feasible Bussard's Inertial Confinement Fusion
EXL engine is? It is not laser ICF but electrostatic. I read an old
article about using one to power a large arcjet and just wanted to
know if it actually works?

(George) wrote in message . com...
Does anyone know how feasible Bussard's Inertial Confinement Fusion
EXL engine is? It is not laser ICF but electrostatic. I read an old
article about using one to power a large arcjet and just wanted to
know if it actually works?

There are several researchers who experiment with fusors. These are
vacuum devices that produce fusion reactions. Essentially they consist
of two spherical and concentric wire mesh grids that accelerate ions
inwards to the center where they collide and fuse. Significant numbers
of fusion reactions can be produced this way. As far as I can tell the
reaction rate is limited by ion density which is limited by the space
charges, the ions repell each other.

Zoltan

(Zoltan Szakaly) wrote in message om...
(George) wrote in message . com...
Does anyone know how feasible Bussard's Inertial Confinement Fusion
EXL engine is? It is not laser ICF but electrostatic. I read an old
article about using one to power a large arcjet and just wanted to
know if it actually works?

There are several researchers who experiment with fusors. These are
vacuum devices that produce fusion reactions. Essentially they consist
of two spherical and concentric wire mesh grids that accelerate ions
inwards to the center where they collide and fuse. Significant numbers
of fusion reactions can be produced this way. As far as I can tell the
reaction rate is limited by ion density which is limited by the space
charges, the ions repell each other.

Zoltan

Anybody knows the status of Dr. Bussard's work?

I only found a reference to 1e10 number of reactions per second. This
is from prior work. I see no data on recent accomplishments. I haven't
even found their company website. Is this work classified?

Zoltan

George wrote:

Does anyone know how feasible Bussard's Inertial Confinement Fusion
EXL engine is? It is not laser ICF but electrostatic. I read an old
article about using one to power a large arcjet and just wanted to
know if it actually works?

Not so far.

There's no question that electrostatic confinement can produce fusion;
there are a variety of designs for neutron generators based on
electrostatic confinement, including some you can literally build at
home. However, these devices are all far short of producing net power
output, and are limited in power density by the fact that they use solid
grids to control the ion motion.

Bussard has developed a more advanced electrostatic confinement concept
with no grids. He's worked on in for many years and remains convinced
that it will generate net power if scaled up to an appropriate size, but
has not been able to get a large experiment funded; the small
experiments he has done are inconclusive.

Many (probably most) other fusion researchers are equally convinced that
it will never reach breakeven because of fairly fundamental physical
limits, mainly related to how fast the radial motion of the ions
"thermalizes" (i.e., becomes random motion).

Jordin Kare

Bussard has developed a more advanced electrostatic confinement concept
with no grids. He's worked on in for many years and remains convinced
that it will generate net power if scaled up to an appropriate size, but
has not been able to get a large experiment funded; the small
experiments he has done are inconclusive.

Many (probably most) other fusion researchers are equally convinced that
it will never reach breakeven because of fairly fundamental physical
limits, mainly related to how fast the radial motion of the ions
"thermalizes" (i.e., becomes random motion).

Jordin Kare

The conventional fusors loose energy because of the collisions with
the grid wires. Bussards new concept has magnetic fields preventing
such collisions. I just spent a day reading the relevant patent
applications and find the concept very nice. I would love to work on
developing it because this could really put us into the space
business. I have read somewhere that they got 1e14 reactions per
second and got better than breakeven performance. I can't remember
where I read this. Bussard's reactor also uses electron injection to
reduce the effect of the positive space charges. There is an electron
cloud in the center kept there by the magnetic fields.

Zoltan

(Zoltan Szakaly) writes:

The conventional fusors loose energy because of the collisions with
the grid wires.

That is only one of the many, MANY different ways a "fusor" loses energy.
Even if "grid losses" could be brought to zero, the ions will still
lose energy to collisions and charge-exchange reactions with the
zillions of residual neutral gas molecules that still fill the chamber
at even the best vacuum we can achieve in a laboratory. Furthermore,
even if losses to background gas could be completely eliminated,
because the ion thermalization timescale is many, many orders of
magnitude shorter than the mean time between fusion reactions,
there will be constant losses due to ions in the thermal tail
being upscattered until they have enough energy to reach the cathode
of the electron gun, or some other negatively-charged electrode.
Since charge is conserved, at equilibrium, the ion current must equal
the electron current, so _some_ part of the chamber must necessarily be
being bombarded by tens of amperes of ion current, heating it to high
temperatures and sputtering it to death.


Bussards new concept has magnetic fields preventing such collisions.

Sorry, but Liouville's Theorem makes that physically impossible.
If the electrons can get _into_ the chamber, it necessarily follows
that the ions must also be able to get _out_ of the chamber, to bombard
that same electrode.


I have read somewhere that they got 1e14 reactions per second and got
better than breakeven performance. I can't remember where I read this.

That is probably because what you think you have read is not true.
Reality check time: With each D-D fusion reaction releasing an average of
about 3.7 MeV (5.9e-13 Joule), the _MAXIMUM_ possible power output that
could be obtained even with your outrageously high alleged claim of 1e14
reactions per second would be about 60 Watts. Since the electron beam
current is many amperes, at tens of kilovolts of energy, the _MINIMUM_
possible power consumption for the device must be on the order of many
tens of kilowatts. Conclusion: There is _NO WAY_ this device can break even
at a mere 1e14 reactions per second --- and in point of fact, the best
performance anyone has ever gotten from one of these devices is still
_TEN BILLION TIMES SMALLER THAN BREAKEVEN_.


Bussard's reactor also uses electron injection to reduce the effect of
the positive space charges. There is an electron cloud in the center kept
there by the magnetic fields.

On the contrary: In Bussard's concept, the center of the chamber must be a
magnetic null. Furthermore, the electrons are not "kept" there at all;
they simply vacillate there briefly due to their (small) inertia as they
are slowed by the electrostatic potential created by their large collective
negative space-charge density, before being repelled back outward and
collected by the anodes of the electron guns. The resulting electron density
peak is known as a "virtual cathode;" the effect and its nature have been
well understood since the early days of vacuum tubes.

You really _should_ try looking this stuff up before posting on it. Patent
applications don't count: Their contents are always as vague and as general
as possible, in an attempt to establish legal priority against as many
variations on the device as that patent attorney can think of. Patents do
=NOT= provide enough technical information to actually build the device !!!


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

Bussard's reactor also uses electron injection to reduce the effect of
the positive space charges. There is an electron cloud in the center kept
there by the magnetic fields.

On the contrary: In Bussard's concept, the center of the chamber must be a
magnetic null. Furthermore, the electrons are not "kept" there at all;
they simply vacillate there briefly due to their (small) inertia as they
are slowed by the electrostatic potential created by their large collective
negative space-charge density, before being repelled back outward and
collected by the anodes of the electron guns. The resulting electron density
peak is known as a "virtual cathode;" the effect and its nature have been
well understood since the early days of vacuum tubes.

You really _should_ try looking this stuff up before posting on it. Patent
applications don't count: Their contents are always as vague and as general
as possible, in an attempt to establish legal priority against as many
variations on the device as that patent attorney can think of. Patents do
=NOT= provide enough technical information to actually build the device !!!


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'


He must be doing something right, I think he got 5 million last year.

Zoltan