- Rishi Gohil
- ChE 379: Energy Technology and Policy
- Dr. Thomas Edgar
- Fall 2007
- Energy generated by joining two elements with low atomic numbers.
- Most efficient reaction known is fusion of Hydrogen isotopes, Deuterium and Tritium, to form Helium.
- Fusion is source of energy for stars and the Sun.
- High temperatures > 100 million degrees Kelvin needed for fusion on earth
- At high temperature, the gas mixture forms a plasma (hot, electrically charged gas)
Nuclear Fusion - This reaction releases 17.6 MeV of energy. No limit on amount of fusion that can occur (unlike fission).
Requirements for Fusion Reaction - Plasma Temperature:100-200 million Kelvin
- Needed to overcome natural positive repulsive forces of plasma ions
- Energy Confinement Time: 4-6 seconds
- The Energy Confinement Time is a measure of how long the energy in the plasma is retained before being lost.
- Central Density in Plasma:1-2 x 1020 particles m-3
- Large density needed because number of fusion reactions per unit volume is roughly proportional to the square of the density
Plasma Toroid (Tokamak) Challenges - Current research in controlling high temperature plasma
- How to heat plasma to >100 million deg C.
- How to confine such a plasma
- How to sustain the reactions.
Advantages - Abundant fuels: Deuterium (from water), Tritium (from Lithium) and Lithium (plentiful on Earth’s crust).
- Inherently safe: Because conditions for reaction are stringent and small amounts of fuel used
- Environmentally safe: No greenhouse gas emissions and byproduct of reaction is Helium.
JET (Joint European Torus) - JET: World’s largest nuclear fusion research facility
Fusion Reactor - EU to build pilot fusion reactor, Iter.
- Cost: 4.57 Billion EURO (2000 prices) over 10 yrs
- Life: 35 years
- Countries Involved: 7
- Design: reactions occur in 100 million degree gas (plasma) suspended in donut shaped magnetic field.
- Problems: Sustained and stable reactions
- Potential: 500 MW output from 70 MW power input during pulses of at least 400 secs.
- If technology works commercial reactor, Demo, will be built.
- Advantages: No greenhouse emissions, inherently safe due to malfunction shutdown systems, no high-level long-lived radioactive waste produced.
Iter Timeline References - "Nuclear Fusion 'Put to the Test'" BBC NEWS 17 Feb. 2005. 19 Nov. 2007 .
- “Fusion Power." United Kingdom Atomic Energy Authority. 20 Nov. 2007. .
- "JET." EFDA. 20 Nov. 2007. .
- “Nuclear Fusion” howstuffworks.19 Nov 2007. Craig Freudenrich, Ph.D.
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