Introduction to Fusion

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Introduction to Fusion

• Fusion and Tokamaks
• Fusion Reactions
• Thermonuclear Reactions
• Power Balance
• Ignition

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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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Tokamaks
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JET News - December 1997 JET IMPROVES ITS WORLD
RECORD PERFORMANCE
The NEWS that two new world records had been
set by JET came just hours after the Director,
Dr Martin Keilhacker had addressed
representatives of the worlds media at a press
conference held at the Royal Society, London, on
31 Octorber. That days experiment had
resulted in new figures of 16 MW of peak fusion
power, an improvement of 3MW, and a new ratio of
power out to power in of 65, 5 up on the
previous record.
On 5 November, JET achieved 21 Mega-joules of
fusion energy, increasing its own best
performance by a further 7 MJ. This was
announced on the same day at the Fusion
Exhibition in Brussels by Professor Troyon,
Chairman of the JET Council.
WHAT JET HAS ACHIEVED THIS YEAR
JET has set three new world records 21 MJ
of fusion energy 16 MW of peak fusion power
and a ration of fusion power produded to net
input power of 65
JET has demonstrated that, using
deuterium-tritium fuel, there is a 25 reduction
in the power needed to maintain high confinement
in operation
JET has tested the first large scale plant of
the type needed to supply and process tritium in
a future fusion power station
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Various Fusion Reactions
3.5MeV 14.1MeV 17.6MeV
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Coulomb Barrier
Potential Energy vs. Nuclear Separation
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Cross Sections
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Reaction Rates for Thermonuclear Fusion
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Power Balance
Heating power per volume
?-particle heating power
Energy loss
Energy confinement time
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Ideal Breakeven and Lawson Criterion

• Ideal breakeven perfect particle confinement,
  bremsstrahlungfusion power

• Lawson criterion
• finite particle confinement, ?p
• power station efficiency, ?1/3

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Ignition Condition
PH lt 0
At T30keV,
Q 1 breakeven, Q ? ignition
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Ignition Condition Triple Products
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Approach to Ignition
Constant confinement time
Ignition
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Approach to Ignition Cordey Pass
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Stability for Alpha Particle Heating
Constant confinement time
condition for stability at ignition(PH0)
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Stabilizing Effect from Confinement Degrade
unstable
stable