Thermonuclear Fusion

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Thermonuclear Fusion A New Hope Jon
Thoms physics_at_scientist.com
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What is fusion?
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Why fusion?

• Inexhaustible Energy
• Potentially cleaner than fission
• Space Exploration

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Its the next logical step
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How do we do Fusion?

• Gravitation Confinement
• Inertial Confinement
• Magnetic Confinement

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The Sun confines plasma with its gravity
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Heres the easy way to do inertial confinement.
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Inertial Confinement with a Laser
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The Z Machine
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Magnetic Confinement A Tokamak ITER
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Challenges for the Tokamak

• Disruptions
• Magnetic Field Gradient
• Plasma Current

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A Conceptual Design Tokamak style fusion
reactors have been the dominant type in plasma
physics experiments. Many of the disruptions and
drifts that plague this type of reactor tend to
flow in the direction of decreasing magnetic
field. Since the magnetic field is stronger
nearer to the center of the tokamak, disruptions
and drifts cause plasma to flow away from the
center. A feature of the tokamak used to combat
this effect is to have a current flowing within
the plasma so that the magnetic field lines twist
so that the drifts are averaged as sections of
plasma spend some time close to the center and
some time far from it. Since drifts and
disruptions tend to flow in the direction of
decreasing magnetic field, some confinement
schemes have been suggested to keep the plasma in
a low field region so that the plasma would have
to move through a higher field region to escape
the device. This conceptual design employs two
toroidial coils, inner and outer, in such a way
that the inner coil creates a void in the
magnetic field generated by the outer coil. This
allows for a low field region in which the plasma
can become homogenized. Any path leading out of
the low field region requires the plasma to move
in the direction of increasing magnetic field.
The inner coil also provides the field otherwise
generated by plasma current in a tokamak, so
there is no need to induce a current in the
plasma. Since the inner coil is submerged in the
plasma, the turns of the coil are spaced out so
that the field generated shields the inner coil
from the plasma. Single particle simulations were
conducted on this design that show particles
being confined indefinitely. Magneto hydrodynamic
(MHD) simulations will be warranted if there is
significant interest in this design.
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A possible reactor design
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(No Transcript)
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Magnetic Surfaces at the Midplane
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Magnetic Field Magnitude
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The Simulated Path an Ion Takes in the Reactor
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A Simulation Rendered in DirectX
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Future Work
Ultimately MHD simulations will be needed to
validate the merit of the design. Short of this,
its possible that a scale model can be tested on
lower temperature plasmas. A support system (or
levitation system) for the inner coil will need
to be developed. The supports may need to be
magnetically shielded since they will have to
pass through a region containing plasma. Its
possible the plasma density will be low enough on
the inner edge of the inner coil (where the
magnetic field is highest) for supports to be
placed there without having to divert the plasma
with magnetic shielding or otherwise.