the sun

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

Fusions-energi

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