Transcript Nuclear Fusion powering the universe

Nuclear Fusion Powers the Universe
The Fusion Process
Neutron proton
Two nuclei combine into one
nucleus plus a nucleon is called
nuclear fusion, a nuclear reaction.
Collision
The picture here illustrates the
fusion of
2D
+ 3T  4He + n
that releases a lot of energy.
Fusion
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Nuclear Fusion Energy
Variation of ME with A
for Some Stable Nuclides
ME amu
3
0.01
He
n
0.005
U
H
Fusion Energy
0.0
4
–0.005
He 12
C
Pb
Fe
Fusion
A
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Nuclear Fusion in Stars
The solar system
Solar system NASA
These links may move
Stars are giant fusion reactors.
E = mc2
1H, 2D
3T, 4He
Nuclear fusion reactions
provide energy in the Sun and
other stars. Solar energy
drives the weather and makes
plants grow.
Energy stored in plants
sustains animal lives, ours
included.
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Nuclear Fusion and the Sun
The birth of the 4.5e9 year old Sun
Sun-Earth Distance (149,597,870.7 km or 8.3 light minutes) is an
Astronomical Unit (AU).
Alpha (A+B+proxima, Centauri triple star system nearest to the sun
parallax angle of 0.76-arcsec) is 4.35-4.22 light years from the Sun.
Sun Mass is 333,000 times that of the Earth.
The sun is a big nuclear fusion reactor, 75% H and 25% He.
Sun radius (695000 km) is 109 times that of the Earth (6.4e3 km).
Sun emits 3.861026 watts, ~ 8 kwatt/cm2, 0.14 watt/cm2 reach the
earth atmosphere (solar constant).
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The Sun
Core:
Radius = 0.25 Rsun
T = 15 Million K
Density = 150 g/cc
Envelope:
Radius = Rsun = 700,000 km
T = 5800 K
Density = 10-7 g
Life of Star:
tug-of-war between Gravity &
Pressure
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The Sun
The sun flare 
The corona during
an eclipse 
The aurora
corona during an eclipse
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The
solar
surface
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Effective Cross Section (mb) of Fusion Reactions
10000
1000
D + T  4He + n
100
Cross sections data
from reactions studied
using particles from
cyclotron
D + D  3T + p
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7Li
D + D  3He + n
1.
D + 3He  4He + p
0.1
10
20
30
40
50
Nuclear Fusion
Cross Sections
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Fusion
60
keV
(p, n) 7Be
3T (p, n) 3He
1H (t, n) 3He
2D (d, n) 3He
2D (t, n) 4He
3T (d, n) 4He
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Nuclear Fusion Energy for D-T Fusion
Estimate the fusion energy for
D + T  4He + n
Estimate the fusion energy Q
The mass excess (MeV) are given below every species.
D + T
 4He + n + Q
13.136 + 14.950 = 2.425 + 8.070 + Q
Q = 17.6 MeV/fusion
This amount is 3.5 MeV/amu compared to 0.8 MeV/amu for fission.
Estimating Q is an important skill. Mass and mass excess can be used,
the latter is usually given to unstable nuclides.
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Nuclear Fusion Energy for Fusion Reactions
Common fusion reactions and their Q values
D + D  4He + 23.85 MeV (hypothetical)
H + H  D + + + n + 1.44 MeV
D + T  4He + n + 17.6 MeV
D + 3He  4He + p + 18.4 MeV
D + D  3He + n + 3.3 MeV
D + D  3T + p + 4.0 MeV
See Interactive Plasma Physics Education Fusion
Experience : http:// ippex.pppl.gov/
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Nuclear Fusion and Plasma
D and T mixtures have to be
heated to 10 million degrees. At
these temperatures, the mixture is
a plasma.
Plasmas
A plasma is a macroscopically
neutral collection of charged
particles.
Ions (bare nuclei) at high
temperature have high kinetic
energy and they approach each
other within 1 fm, a distance
strong force being effective to
cause fusion.
Fires
Stars
Neon lights
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Nuclear Fusion and Plasma Confinements
Three confinement methods
fd3.gif from ippex.pppl.gov/ippex/module_5/see_fsn.html
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Nuclear Fusion and Plasma - kinetic energy
Maxwell-Boltzmann Distribution
Fraction
Kinetic energies of
particles in plasma
follow the MaxwellBoltzmann distribution
0.003
0.002
4 amu 50 K
0.001
4 amu 500 K
1000
2000
Speed (m/s)
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Nuclear Fusion and Plasma - particle motion
Motion of Nuclei and Electrons in a
Magnetic Field
+
Charged particles avoid crossing magnetic lines.
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Nuclear Fusion using
Magnetic Plasma Confinement
Magnetic Mirror Confinement
Plasma
A Magnetic
Bottle for
Plasma
Confinement
Magnetic lines
A plasma distorts magnetic field or bends magnetic lines.
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Nuclear Fusion using Tokamak
The Tokamak
technology for
plasma
confinement in
fusion
fd4.gif<=ippex.pppl.gov/ippex/module_5/see_fsn.html
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Nuclear Fusion using Magnetic Confinement
JET:The Joint European Torus
Program
Tokamak shapes like a donut
confining the plasma in a circular
motion inside the Tokamak.
PSFC: MIT Plasma Science and
Fusion Center
fd6.gif<=ippex.pppl.gov/ippex/module_5/see_fsn.html
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Nuclear Fusion Bombs
A thermonuclear Bomb consists of explosives, fission fuel, and D, T,
and Li.
A thermonuclear bomb begins with the detonation of small quantities
of conventional explosives. The explosion starts fissionable chain
reaction that heats to 1e7 K to ignite a chain of fusion reactions.
2D
+ 3T  4He + n + 17.6 MeV
n + 6Li  T + 4He ( = 942 b)
n + 7Li  T + 4He + n ( = 0.045 b)
A neutron bomb is a fusion bomb designed to release neutrons.
A cobalt bomb is a dirty bomb to kill using radioactive 60Co.
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Nuclear Fusion Energised the Cold War
During WW2, the USSR competed with UK and US for military
superiority. The Cold War started.
Sept. 23, 1949, President Truman told the world about the Soviet
explosion of A-bomb.
The US stepped up to develop the H-bomb.
1952, Nov. 1. US tested the first H-bomb at Enewetak
1953 the USSR tested an H-bomb
Britain, France, and China also have tested H-bombs.
The cold war was red hot until the former USSR disintegrated.
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H-bomb
Fusion
Nov. 1, 1952, the first Hbomb Mike tested,
mushroom cloud was 8 miles
across and 27 miles high;the
canopy was 100 miles wide,
80 million tons of earth was
vaporized.
H-bomb exploded Mar. 1,
1954 at Bikini Atoll yielded 15
megatons and had a fireball 4
miles in diameter.
20 100
USSR H-bomb yields
megatons.
Nuclear Fusion under Controlled Conditions
Humans had controlled fission chain reactions before testing bombs.
1952, Nov. 1. US tested the first H-bomb at Enewetak, controlled
sustained fusion reactor has yet to be achieved.
High temperature and high particle density for long period of time are
the conditions for fusion.
Magnetic and inertia confinements keep particle density high.
Lawson criterion requires confinement time times particle density
reach 1e20 s m-3.
Fusion Links: http:// www.
physics.auburn.edu/~plasma/fusion/fusion_lab/links.html
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Nuclear Fusion Research
Nuclear fusion research is costly, requiring an international effort.
Plasma confinement by torus offers a hope for success.
1968, the USSR reported achieving 1.0e7 K in Tokamak, and and later
reached 1.0e8 K in Tokamak fusion test reactor (TFTR).
Tokamak technology is used in JET and Princeton Large Torus.
Tokamak in the Soviet achieved 5e6 K and density 5e19 p m-3 for D
plasma in 1996.
Strong magnetic field using superconductors is also used.
Laser heating frozen pellets in inertia confinement had some success.
Break even points have been reached in 1995.
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Fusion Research – cont.
The Princeton Large Torus achieved 510 million K, before
decommissioned Oct. 2002.
Simulations made possible by advances in parallel processing allow us
to realistically visualize plasma behavior predicted by advanced
models.
Improved heat retention achieved by plasma flow toward the outside,
instead of flowing close to the center (theory and experiment).
Shear flow pattern also made higher temperature possible.
Understanding of plasma led to National Spherical Torus Experiment
(NSTX) at PPPL, and perhaps other places.
NSTX may achieve self-sustaining.
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Fusion Research – cont.
In addition to optimizing the plasma configuration, future fusion research
these are likely to include
a burning (self-heated) plasma experiment,
an engineering test facility,
facilities for testing fusion materials and components, and then a
demonstration plant, which would put net electricity onto the grid.
It may be possible to eliminate one step by combining the burning plasma
experiment and engineering test facility into one device.
The spherical torus configuration, being developed through NSTX, may
provide an excellent test bed for the development of materials and
components for the demonstration power plant.
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Nuclear Fusion of Protons - hydrogen cycle
The Sun derives energy from fusion of protons. There are
many possibilities, but two detailed cycles were proposed.
The hydrogen cycle:
H + H  2D (+e–) + + + n
2D + H  3He + 
3He + 3He  4He + 2 H
net
4 H = 4He (+ 2e–) + 2+ +2  + 2 n + 26.7 MeV
The carbon cycle will be described next.
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Nuclear Fusion of Protons - carbon cycle
The hydrogen cycle.
The carbon cycle:
12C + H  13N + 
13N  13C (+ e–) + + + n
13C + H  14N + 
14N + H  15O + 
15O  15N (+ e–) + + + n
15N + H  12C + 4He + 
net
4 H = 4He (+ 2e–) + 2+ +4  + 2 n + 26.7 MeV
(similar to the hydrogen cycle)
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Nuclear Fusion in Stars
Nuclear fusion reactions
The hydrogen cycle
The carbon cycle
Life of a Star
Condense mass
Protostar
Star (stable situation)
Red Giant
White Dwarf & Planetary Nebula
Nova or Supernova
Neutron Star or Black Hole
Others reactions
3He + 4He  7Be4 + 
7Be + H  8B5 + 
8B  8Be + +
8Be  2 4He +  (major)
8Be + 4He  12C (minor)
Additional reactions
12C + 4He  16O + 2.425 MeV
16O + 4He  20Ne + 4.73 Me
4He + 20Ne  24Mg + 9.31 MeV
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Nuclear Fusion Catalysed by Muons
Muons, m– and m+ are 2nd generation leptons, 207 time the mass
of electron, and holds 2 D 74/207 (= 0.35) pm apart. Frank and
Sakharov independently suggested muons would help two
deuterium nuclei to fuse.
2D  3He + n + 3.3 MeV
2
or
2D  3T + p + 4.0 MeV
2
Alvarez and colleagues suggested a muon catalysed reaction
2D–1H
+m
3He
+m
with weak evidence.
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Nuclear Fusion and Electrolysis - cold fusion
Cold fusion refers to fusion reactions at room temperature.
Pons and Fleischmann electrolyzed a basic lithium oxide solution
containing 0.1 mol of LiOD per litter of D2O solution, using
palladium electrodes. Unexpected amount of heat destroyed their
experiment equipments, and they claimed palladium catalyzed
cold nuclear fusion.
Evidence was not sufficient, and no one else has reproduced the
result yet.
Jones and co-workers also claimed cold fusion as energy source
in the Earth interior.
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Fusion Research in U.S.A.
•Princeton Plasma Physics Laboratory (PPPL).
•Oak Ridge National Laboratory (ORNL).
•Massachusetts Institute of Technology, Alcator CMod.
•University of Wisconsin, HSX.
•University of Texas, Fusion Research Center.
•Max Planck Institut fur Plasmaphysik, Wendelstein 7AS
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Fusion Research World Wide
UK: EFDA-JET, START, MAST
Small Tight-Aspect Ratio Tokamak - operational at Culham from 1991 until
1998. This 'baby' tokamak was the first high temperature spherical tokamak
MAST - Mega Amp Spherical Tokamak - START's bigger brother (approximately
twice as big), now operating at Culham.
JAPAN: JT-60
RUSSIA: ?
CANADA: Canadian Fusion Fuels Technology Project (CFFTP)
http:// epub.iaea.org/ fusion/public/ws97/node42.html
March 2002, bubble fusion was reported in Science, unconfirmed.
International collaboration called ITER expected to produce
fusion energy at the rate ofFusion
a commercial power plant by the
year 2010
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Nuclear Fusion in Summary
Recognize possible fusion reactions
Evaluate fusion energy for fusion reactions
Describe properties of plasma and principle of magnetic confinement
Discuss inertia and other confinements for fusion reaction
Appreciate and anticipate difficulties in fusion experiments
Understand weapons and their social and international impact
Judge claims of fusion reaction and designs of fusion experiment
Develop an interest in fusion and keep up-to-date with fusion research
Fusion Timeline:
informationheadquarters.com/List_of_themed_timelines/nuclear_fusion.shtml
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