Introduction to Nuclear Fusion
Brought to you by:
Allen Chen
In Association with:
Nagoya University
Kyushu University
EFDA-JET: Joint European Torus
Overview
What is Fusion?
Why do we need it?
How do we achieve it?
The OMEGA facility: Inertial Confinement Fusion at Rochester
What is Fusion?
Lets look at our sun!
^Its huge!!
Diameter: 1 390 000 km
Fits 109 Earths and 10 Jupiters across
^Its massive!!
2.00x10
30
kg
333,000 x Earths mass, 1000 x Jupiters
Mostly H (92.1%), He (7.8%), others (~0.1%, mostly O, N,
and C)
^Its powerful!!
4.0x10
20
megawatts
75 x largest H-bomb ever exploded, per second!!
4.6 billion years and counting!
Whats really going on inside?
Corona
Radiative
Zone
Convective
Zone
Core:
This is the source
of Suns (and all
stars) POWER!
The Structure of the Sun
Rarefied upper atmosphere
Extends millions of kms into space
Only visible during eclipse
Temperature reaching over 1 million K
Chromosphere
color lower atmosphere
Average temperature about 20,000 K
Only visible during eclipse
Very thin (2000-3000 km)
Photosphere
sphere of light, suns
surface
The deepest we can see into
the Sun
Temperature at ~ 5800 K
Non-uniform surface rotation
can be seen (a lot like Jupiter
and Saturn)
Conditions at the Suns Core
^ Extremely Hot!!
~16 000 000 K
This means the protons in the core have enough kinetic
energy to overcome the Coulomb repulsive force!
^ Extremely Dense!!
Due to the enormous gravity, the pressure in the core is ~250
000 000 000 atmospheres
Density is more than 150 times that of water!
This means there are enough protons in a small volume for
long enough period of time to collide with each other!
Essentially:
In the Suns core, the temperature, the density, and the
confinement time are all at suitably large values for FUSION
REACTION!
Every second, the Suns core fuses ~700 Mt of hydrogen into
~695 Mt of helium and produces 4x10
20
MJ of energy in the
form of gamma rays!!
Where is the energy coming from?
p
1
H
1.008 AMU 1.674 x 10
-27
Kg
p p p p
4.032 AMU 6.695 x 10
-27
Kg
p
n
p
n
4
He
4.003 AMU 6.647 x 10
-27
Kg
The missing mass, or mass defect, in the He
nucleus has an equivalent energy (E=mc
2
):
E
B
(He) 4.8 x 10
-29
kg x c
2
4.3 x 10
-12
J 27 MeV
This energy is called the binding energy of nucleons.
The amount of mass converted into energy when
nucleons bind together under strong nuclear force.
The amount of energy needed to break a nucleus into
separate nucleons
This is the energy of nuclear power (Fusion and Fission)!!
Mass( ) Mass( ) 0.029 AMU 4.8 x 10
-29
kg p p
p p
p
n
p
n
Binding Energy/Nucleon
B
I
N
D
I
N
G
E
N
E
R
G
Y
i
n
M
e
V
/
n
u
c
l
e
o
n
Fission
F
u
s
i
o
n
Iron: the most stable element in the universe!!!
Very heavy elements
produce energy when
they break up into
lighter elements!
Very light elements
produce energy when
they combine to form
heavier elements!
Other Fusion Reactions
O D(
2
H)+T(
3
H)
4
He (3.5 MeV) + n (14.1 MeV)
O D+D (50%) T (1.01 MeV) + p ( 3.02 MeV) (50%)
(50%)
3
He (0.82 MeV) + n ( 2.45 MeV) (50%)
O D+
3
He
4
He (3.6 MeV) + p (14.7 MeV)
O T+T
4
He + 2 n + 11.3 MeV
O
3
He+
3
He
4
He + 2 p
O
3
He+T(51%)
4
He + p + n + 12.1 MeV
(43%)
4
He (4.8 MeV) + D ( 9.5 MeV)
(6%)
4
He (0.5 MeV) + n ( 1.9 MeV) + p (11.9 MeV)
O p+
6
Li
4
He (1.7 MeV) +3He (2.3 MeV)
O n+
6
Li
4
He (2.1 MeV) + T (2.7 MeV)
O D+
6
Li 2
4
He + 22.4 MeV
O
3
He+
6
Li 2
4
He + p + 16.9 MeV
O p+
7
Li (20%) 2
4
He + 17.3 MeV
(80%)
7
Be + n 1.6 MeV
O p+
11
B 3 He
4
+ 8.7 MeV
Easiest to achieve!
Most abundant fuel!
No neutrons!
Breeds Tritium
p n
n
n
p
p
n
p
n
n
Why Fusion?
Mass-Energy Conversion Efficiency
Complete Mass-To-Energy Conversion (E=MC
2
)
9.0x10
7
GJ/kg (100 %)
1 gram of matter 9 x 1013 J
enough to boil 500 Mt of water!!
Or supply the energy needs of Japan for 2 minutes!!
Nuclear Fusion
4H He
6.4x10
5
GJ/kg (0.71 %)
D+T He + n
3.4x10
5
GJ/kg (0.38 %)
Nuclear Fission
235
U
144
Ba +
89
Kr + 3n
7.3x10
4
GJ/kg (0.08 %)
Chemical Reaction
2H
2
+ O
2
2H
2
O (space shuttle fuel)
0.142 GJ/kg (1.6x10
-7
%)
CH
4
+ 2O
2
CO
2
+ 2H
2
O (natural gas fuel)
0.055 GJ/kg (6.1x10
-8
%)
C + O
2
CO
2
(coal burning)
0.033 GJ/kg (3.7x10
-8
%)
Benefits: Nothing Else Comes Close
O Abundant fuel, available to all nations.
Deuterium (D) and Lithium (L)
Virtually unlimited supply
O Environmental advantages.
Zero carbon emissions
Intermediate/Low level radioactivity at most
Spill and accident avoidance
O Cannot explode, cannot melt down.
<5 minutes of fuel in plasma at all times
Fusion reaction will die if control fails
O Low risk of nuclear materials proliferation.
No fissile materials
O Extremely high energy concentration.
Minimal land use compared to solar, wind, large hydro
O Not subject to daily, seasonal or regional weather variation.
No need for energy storage or long distance transmission
The Quest for Fusion
The Hydrogen Bomb
Inertial Confinement Fusion
Magnetic Confinement Fusion
Conditions at the Suns Core
^ Extremely Hot!!
~16 million K
This means the protons in the core have enough kinetic
energy to overcome the Coulomb repulsive force!
^ Extremely Dense!!
Due to enormous gravity, the pressure in the core is ~250
billion atmospheres!
Density is more than 150 times that of water
This means there are enough protons in a small volume for
long enough period of time to collide with each other!
Essentially:
We need high temperature, high density, and long
confinement time to achieve FUSION REACTION!
How can we reproduce these conditions on Earth?
Edward Teller
The Teller-Ulam Design
(Staged Radiation Imposion)
PRIMARY FISSION
SECONDARY FUSION + FISSION
Chemical High
Explosives
Beryllium
Reflector
Levitated
Plutonium Pit
Polstyrene
Radiation
Channel
Hollow Plutonium Rod
(A Fission Spark Plug to
Initiate Fusion Reaction )
Fusion Fuel
(D
2
or
6
LiD)
High-Z (U or W)
Tamper/Pusher
High-Z (U or W)
Radiation Shield
High Z
Hohlraum/Radiation
Case (eg. Lead)
Weapon Case
(eg. Aluminum)
Stanislaw Ulam
Operation Ivy
The Mike Apparatus on Elugelab Island, Marshall Islands,
3000 miles west of Hawaii
The Result of Mike
Mike
10.4 Mt
August 31, 1952
Power of Mike
Mike
Nagasaki-scaled A-Bomb
Inertial Confinement Fusion
O An internal combustion engine method of controlled
fusion reactions
Formally began in 1963
First ruby laser invented in 1960
Declassified in 1992~1993
O Principle Components
Target
Tiny hydrogen bombs (really!) exploding in succession
Direct-drive Targets
Indirect-drive Targets
Driver
We obviously cant use Atom-bombs!
Lasers
Ion Accelerators
X-Ray from Z-Pinch
Nova at LLNL
Direct-Drive ICF Target
Ablated Capsule
Shell Plasma
Atmospheric Formation Compression
Ignition
Fusion Burn
Fusion Fuel
D
2
Gas
D-T Gas Mixture
Plastic Fuel Capsule
Shell/Ablator/Pusher
Driver Energy
Implosive Force
From the Shell
Ablation
Hot Spot
Ignition Beam
(Fast Ignition)
` Efficient in Transporting Driver Energy
to the Fusion Capsule
Very Sensitive to the Spatial Symmetry
of the Driver Beams
ICF Laser Drivers
Operating
Const.
5kJ
700J/5Hz
KrF
KrF
US (NRL)
US (NRL)
NIKE
Operating
Operating
8kJ/8b
30kJ/32b
Nd:Glass
Nd:Glass
China (CAEP)
China (CAEP)
SG-II
SG-III
Shut Down
Operating
Const. (2008)
6kJ/2b
60kJ/86
1.8MJ/240b
Nd:Glass
Nd:Glass
Nd:Glass
France
France (CEA)
France (CEA)
PHEBUS
LIL
LMJ
Operating
Const (2002)
0.1PW/0.5ps
1PW/0.5ps
Nd:Glass
Nd:Glass
UK
UK
VULCAN
RAL-PW
Operating
Operating
Operating
20kJ/12b
100TW/1ps
1PW/0.8ps
Nd:Glass
Nd:Glass
Nd:Glass
Japan (Osaka U)
Japan (Osaka U)
Japan (Osaka U)
GEKKO XII
GEKKO-PWM
GEKKO-PW
Operating
Shut Down
Const. (2008)
30kJ/60b
40kJ/10b
1.8MJ/192b
Nd:Glass
Nd:Glass
Nd:Glass
US (Roch. U)
US (LLNL)
US (LLNL)
OMEGA-U.G
NOVA
NIF
Current Status Beam
Parameters
Scheme Nation Name of
Facilities
OMEGA, LLE Rochester University
National Ignition Facility
Magnetic Confinement Fusion
Whats a Plasma?
Tokamaks
T
e
m
p
e
r
a
t
u
r
e
gas
plasma
Solid
Liquid
A plasma is quasi-neutral, i.e. it contains nearly equal
amount of free-moving positive and negative charges.
Plasma? The Fourth State of Matter
What Can We Do With a Plasma?
O A Plasma Conducts Electricity
Ohmic Heating
A plasma current heats itself.
Faradays Induction
A plasma current creates magnetic field.
Lorenzs Force
Plasma motion can be Influenced by magnetic fields.
Nucleus (+)
Electrons (-)
B
The plasma is confined by the magnetic field B if the
gyro-radius is less than the dimension of the plasma
The Tokamak
Transformer Core
Transformer
Primary Coil
B
I
p
e
+
e
-
Vacuum Vessel
First Wall
External
Superconducting
Toroidal Magnets
External Plasma-
Shaping Magnets
DD/DT Fuel (heated
to become plasma)
B
Toroidal Current (Secondary Coil)
Toroidal Magnetic Field
Poloidal Magnetic Field
Resultant Helical
Magnetic Field
JET
EFDA, Oxfordshire, UK.
Began operating in 1983
Largest tokamak in the
world
First tokamak to produce a
significant fusion power (2
MW) in 1991 (using D-T fuel)
Highest temperature
achieved > ~ 300 million K
Highest peak fusion power
achieved was 22 MW
2.96m/1.25x2.1m/3.45T/4.8MA
JT-60
JAERI, Naka, Japan
The worlds most powerful fusion reactor!
3.4m/1m/4T/3MA
The JT-60U Success
Q > 1 !!!!
P
out
~ 50 MW
T
ion
~520 million K
nT ~ 1.77x10
10
[Ks10
13
/cm
3
]
ITER, The Next Step
Japan+Canada+EU+Russia+(US?)
Currently in Nagotiation..
Site & Host Country TBD in 2003
