the sun
DESCRIPTION
The energy of the sun comes from fusion of hydrogen nuclei 4H + 2e He + 5 + 2 (+ 26 MeV). H. Bindingsenergi per nukleon. nukleoner. He. The Sun. E = mc 2 m He < 4m H + 2m e. Every second 4 million tons of mass is converted to energy. Fusion is a universal source of energy. - PowerPoint PPT PresentationTRANSCRIPT
The Sun
The energy of the sun comes from fusion of hydrogen nuclei
4H + 2e He + 5 + 2 (+ 26 MeV)
Bindingsenergi per nukleonnukleoner
He
H
E = mc2
mHe < 4mH + 2me Every second 4 million tons of mass is converted to energy
Fusion is a universal source of energy...
... which we would like to exploit directly on Earth
Fusion on Earth
D + T n + He + 17.6 MeV
Li6 + n T + He + 4.8 MeV
Li7 + n T + He + n – 2.5 MeV
Fusion energy
• Inexhaustible• Safe• Short-lived radioactive waste
• No CO2 emission
• Fuels are abundant and geographically distributed
• 15 fusion power stations could cover Denmarks total energy consumption
Increase of CO2 Concentrationbecomes significant
260
280
300
320
340
360
Atm
osp
her
ic C
O2
(p
pm
)
900 1100 1300 1500 1700 1900 2000
Year
Source: F. Joos, J.L. SarmientoPhys. Bl. 51, 5, 405-411 (1995)
Danes and Chinese
• Denmark spends 8291015 joule / year = 26 GW
• A Dane spends 166 109 joule / year = 5.3 kW
• An American spends 15.9 kW
• A Chines spends 0.5 kW
• The Chines want to catch up, so
• They open a new power station every 2 weeks!
• Without drastic action – CO2 emission rate will double in 50 years,
– CO2 concentration in the atmosphere will build up still faster
Potential energy
Electrostatic forces repel
Nuclear forces attract
Fusion ratesMany collissions required for each fusion event
In the sun a proton on average lives several billion years, fortunately.
For exploitation on earth the fusion rate must be so high that the average live time is approximately 100 secondsFusion rate = R n1 n2
T 200 million degrees (20 times T in suns centre)
n 1020/m3
P 10 bar
At that temperature: Plasma
Lightning is a plasma
All stars and much of interstellar space are plasmas
Plasmas with cold ions and hot electrons
We use cold plasmas for deNOx
PlasmaAt temperatures above 10.000 – 100.000 °C gasses turn into plasmas.
A neutral mixture of ions and electrons.
A plasma can be confined by a magnetic field.
Magnetic configurations which can confine a plasma
The Tokamak
Heating methods
Frequency
Intensity
How does one measure a temperature of 100 million degrees?
Laser lightelectron
Doppler frequency shift
The width reveals the electron temperature
JET: Joint European Torus
JET outside
Under construction in 1985
JET outside
1991
NBI
ICRH
Lower Hybrid
JET inside
TEXTORTrilateral Euregio Cluster TEC
FZ-Jülich (D), ERM/KMS (B), FOM (NL)
Outside TEXTOR
Inside TEXTOR
Figure 3. Graphical representation of the quazi-optical antenna inserted into the tokamak’s port (CATIA V5R8).
The system with the receiver (Catia)
ASDEX upgrade, Max Planck Institut for plasmafysik, Garching
(Munchen)
Plasma i ASDEX
Achieved Fuion Power
Energy confinement time
12 minutes
12 hours = Energy / heating power
Fusion power station: > 6 sekunder
Magnetisk Indesluttet Fusions Plasma
Achieved parameters:Temperature (T) 200 MK
Density (n) 1020m-3
Confinement time () 1 sec.
n T 1 atm sec
Target:n T 6 atm sec
Must be increased
Turbulence Transport limits
Increase
Fluktuationer
The road to Fusion
• ITER, science and technology of a burning fusion plasma.– Decision early 2004– 10 years construction, – 20 years scientific exploitation
• DEMO, demonstration fusion reactor– Design begins 2025– Construction starts 2035
• Commercial fusion power 2050
Burning Fusion PlasmaD + T (3.5 MeV) + n (14.1 MeV)
Confined population of fast ions.
Large free energy
Heats the plasma
Drives turbulence
Affects confinement
TransportWhat is the dynamics of the fast ions ?
Can we influence it ?
Fast ions are almost invisible
Fast ions draw a wake in the electron fluid,
Which can be detected by scattering of microwaves
But their wakes give them away
!
Burning Fusion PlasmaD + T (3.5 MeV) + n (14.1 MeV)
Large neutron flux through the inner wall
Cause material changes:
• Hardens
• Swells
• Becomes brittel
Fusion power station