That they are able to simulate a
positive outcome is nice and what it does do is trigger financing to run the
proper experiments. What is happening is
that anyone with skin in the game is playing around with magnetic fields and
any containment strategy to see if it can be optimized in simulation at
all. This all can happen prior to
cutting much metal.
It also means that an experiment
will be a true learning experience that opens avenues for advancement. This is another reason that I am expecting
the fusion problem to not only be solved soon but that it will be solved in
several different ways. This then opens
the door for optimizing applications.
The recent claimed advent of a
over unity heat engine will have a ready market merely because much of what we
do uses heat in the first place. There
is little advantage in shipping electrical power to produce heat if a simply
device will merely heat the water for you as needed
Nuclear fusion simulation shows high-gain energy output
March 20, 2012
Component testing under way at Sandia’s Z accelerator for fast-firing
magnetic method
ALBUQUERQUE, N.M. — High-gain nuclear fusion could be achieved in a
preheated cylindrical container immersed in strong magnetic fields, according
to a series of computer simulations performed at Sandia National Laboratories.
The simulations show the release of output energy that was, remarkably,
many times greater than the energy fed into the container’s liner. The method
appears to be 50 times more efficient than using X-rays — a previous favorite
at Sandia — to drive implosions of targeted materials to create fusion
conditions.
Prototype assembly of MagLIF system - the top and bottom coils enclose
the lit target. (Photo by Derek Lamppa) Click on the thumbnail for a
high-resolution image.
“People didn’t think there was a high-gain option for magnetized inertial
fusion (MIF) but these numerical simulations show there is,” said Sandia
researcher Steve Slutz, the paper’s lead author. “Now we have to see if nature
will let us do it. In principle, we don’t know why we can’t.”
High-gain fusion means getting substantially more energy out of a
material than is put into it. Inertial refers to the compression in situ over
nanoseconds of a small amount of targeted fuel.
Such fusion eventually could produce reliable electricity from
seawater, the most plentiful material on earth, rather than from the raw
materials used by other methods: uranium, coal, oil, gas, sun or wind. In the
simulations, the output demonstrated was 100 times that of a 60 million amperes
(MA) input current. The output rose steeply as the current increased: 1,000
times input was achieved from an incoming pulse of 70 MA.
Since Sandia’s Z machine can bring a maximum of only 26 MA to bear upon
a target, the rese0archers would be happy with a proof-of-principle result
called scientific break-even, in which the amount of energy leaving the target
equals the amount of energy put into the deuterium-tritium fuel.
This has never been achieved in the laboratory and would be a valuable
addition to fusion science, said Slutz.
Inertial fusion would provide better data for increasingly accurate
simulations of nuclear explosions, which is valuable because the U.S. last
tested a weapon in its aging nuclear stockpile in 1992.
The MIF technique heats the fusion fuel (deuterium-tritium) by
compression as in normal inertial fusion, but uses a magnetic field to suppress
heat loss during implosion. The magnetic field acts like a kind of shower
curtain to prevent charged particles like electrons and alpha particles from
leaving the party early and draining energy from the reaction.
The simulated process relies upon a single, relatively low-powered
laser to preheat a deuterium-tritium gas mixture that sits within a small
liner.
At the top and bottom of the liner are two slightly larger coils that,
when electrically powered, create a joined vertical magnetic field that
penetrates into the liner, reducing energy loss from charged particles
attempting to escape through the liner’s walls.
An extremely strong magnetic field is created on the surface of the
liner by a separate, very powerful electrical current, generated by a pulsed
power accelerator such as Z. The force of this huge magnetic field pushes the
liner inward to a fraction of its original diameter. It also compresses the
magnetic field emanating from the coils. The combination is powerful enough to
force atoms of gaseous fuel into intimate contact with each other, fusing them.
Heat released from that reaction raised the gaseous fuel’s temperature
high enough to ignite a layer of frozen and therefore denser deuterium-tritium
fuel coating the inside of the liner. The heat transfer is similar to the way
kindling heats a log: when the log ignites, the real heat — here high-yield
fusion from ignited frozen fuel — commences.
Tests of physical equipment necessary to validate the computer
simulations are already under way at Z, and a laboratory result is expected by
late 2013, said Sandia engineer Dean Rovang.
Portions of the design are slated to receive their first tests in March
and continue into early winter. Sandia has performed preliminary tests of the
coils.
Potential problems involve controlling instabilities in the liner and
in the magnetic field that might prevent the fuel from constricting evenly, an
essential condition for a useful implosion. Even isolating the factors
contributing to this hundred-nanosecond-long compression event, in order to
adjust them, will be challenging.
“Whatever the difficulties,” said Sandia manager Daniel Sinars, “we
still want to find the answer to what Slutz (and co-author Roger Vesey)
propose: Can magnetically driven inertial fusion work? We owe it to the country
to understand how realistic this possibility is.”
The work, reported in the Jan. 13 issue of Physical Review
Letters, was supported by Sandia’s Laboratory Directed Research and Development
office and by the National Nuclear Security Administration.
Sandia National Laboratories is a multi-program laboratory operated by
Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for
the U.S. Department of Energy’s National Nuclear Security Administration. With
main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major
R&D responsibilities in national security, energy and environmental
technologies and economic competitiveness.
Sandia news media contact: Neal Singer, nsinger@sandia.gov (505) 845-7078
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