Fusion: The Power of the Universe

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Introduction

• Fusion The Power of the Universe
• Why Develop Fusion?
• What is Fusion?
• How Does Fusion Work?
• Magnetic Confinement Concepts
• What is a Tokamak?
• What is the Fusion Challenge?
• Tokamaks

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Fusion The Power of the Universe

• Fusion is perhaps the only option for a truly
  sustainable or long term energy source, The fuel
  is virtually inexhaustible and readily available
  throughout the world. Power plant operation will
  be inherently safe without the risk of long-lived
  radioactive waste. Fusion will be environmentally
  sound without atmospheric pollutants or
  contribution to global warming. It will be
  economically attractive and capable of producing
  the energy that future generations will require.
  The sun and stars are powered by fusion.
  Harnessing these reactions to produce energy on
  earth presents a grand challenge to scientists
  and engineers. Steady progress has been made but
  several scientific and technological advances are
  necessary before the dream of commercial
  electricity production will become a reality

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Why develop Fusion?

• By the middle of the next century, the world's
  population will double and energy demand will
  triple. This is due in large part, to the
  industrialization and economic growth of
  developing nations. Continued use of fossil fuels
  (coal, oil and natural gas) will rapidly deplete
  these limited and localized natural resources.
  There is, perhaps, another 50-100 years supply of
  oil and natural gas and enough coal for several
  hundred years. Burning these fossil fuels
  threatens to irreparably harm our environment. On
  the other hand, the deuterium in the earth's
  oceans is sufficient to fuel advanced fusion
  reactors for millions of years. The waste product
  from a deuterium-tritium fusion reactor is
  ordinary helium.

Solar and renewable energy technologies will play
a role in our energy future. Although they are
inherently safe and feature an unlimited fuel
supply, they are geographically limited, climate
dependent and unable to meet the energy demands
of a populous and industrialized world. Another
option, nuclear fission, suffers from a negative
public perception. High-level radioactive waste
disposal challenges and the proliferation threat
of weapons-grade nuclear materials are principle
concerns. The fuel supply in this case is large
but ultimately limited (100-200 years without
breeder reactors).
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What is Fusion?

• Fusion is combining the nuclei of light elements
  to form a heavier element. This is a nuclear
  reaction and results in the release of large
  amounts of energy! In a fusion reaction, the
  total mass of the resultant nuclei is slightly
  less than the total mass of the original
  particles. An example can be seen in the
  Deuterium-Tritium Fusion Reaction.

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What is Fusion?
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When can Fusion Occur?
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How does Fusion work?

• In order for fusion reactions to occur, the
  particles must be hot enough (temperature), in
  sufficient number (density) and well contained
  (confinement time). These simultaneous conditions
  are represented by a fourth state of matter known
  as plasma. In a plasma, electrons are stripped
  from their nuclei. A plasma, therefore, consists
  of charged particles, ions and electrons.
• There are three principle mechanisms for
  confining these hot plasmas - magnetic, inertial
  and gravity.

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Magnetic Confinement Concepts
Good Perpendicular Confinement, but Strong End
Loss
Magnetic Mirror Lawrence Livermore
Flute Instability
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Mirror and Cusp
Mirror
Cusp
Mirror with Ioffe Bar
or Ying-Yang Coil (Baseball Coil)
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Pinches Los Alamos
Z-pinch
?-pinch
Kink Sausage Instabilities
Strong End Loss
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Stellarator Princeton University
Drift Motions in Torus
Figure-8 Stellarator
R
B
B
R
R
B
Electrons drift into page
Electrons drift out of page
Drifts Cancel
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Z-Pinch to Tokamak and RFP
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?-Pinch to FRC and Spheromak
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Magnetic Confinement Stellarators

• Australian National University - H-1.
• Max Planck Institute for Plasma Physics,
  Garching, Germany
• - Wendelstein 7-AS and Wendelstein 7-X.
• Auburn University - Compact Auburn Torsatron
  (CAT).
• Torsatron Stellarator Laboratory of the
  University of Wisconsin, Madison - Helically
  Symmetric Experiment (HSX).
• National Institute for Fusion Science, Nagoya,
  Japan
• - Large Helical Device (LHD) and Compact Helical
  System (CHS)
• EURATOM-CIEMAT - TJ1U Stellarator and TJII
  Heliac, Madrid, Spain.
• TOHOKU UNIVERSITY Heliac (TU-Heliac), Sendai,
  Japan.

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Large Helical Device (NIFS)
W7-X
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What is a Tokamak?

• The most successful and promising fusion
  confinement device is known as a tokamak. The
  word tokamak is actually an acronym derived from
  the Russian words toroid-kamera-magnit-katushka,
  meaning "the toroidal chamber and magnetic coil."
  This donut-shaped configuration is principally
  characterized by a large current, up to several
  million amperes, which flows through the plasma.
  The plasma is heated to temperatures more than a
  hundred million degrees centigrade (much hotter
  than the core of the sun) by high-energy particle
  beams or radio-frequency waves.

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Where Are We?
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What is the Fusion Challenge?

• The ultimate objective of fusion energy research
  is the demonstration of a steady-state, high-gain
  (or "ignited" ) fusion plasma producing
  reactor-level fusion power. To accomplish this
  goal, we must improve our understanding of the
  underlying physics principles and advance the
  state-of-the-art of critical enabling
  technologies.
• Improving physics understanding The transport
  of heat particles from the plasma, the
  contribution of magneto hydrodynamic modes and
  instabilities and the effects of large
  populations of energetic alpha particles are
  examples of areas that require improved physics
  understanding so that techniques can be developed
  to improve the performance and reduce the size
  and cost of future fusion reactors.
• Developing enabling technologies High strength
  materials that do not become excessively
  activated from fusion neutrons or weakened due to
  the nuclear after-heat are needed for the reactor
  structure. First-wall materials with adequate
  thermal conductivity to carry away the heat flux
  from the high temperature fusion plasma are
  required. Large bore, high field superconducting
  magnets are necessary to provide the required
  steady-state confinement of fusion plasmas.

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Tokamaks