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Demo
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{{wiktionarypar|demo}}
'''Demo''' may refer to:
*
Demo (music), a song recorded for reference rather than for release
*
Demoware, a type of shareware
**
Game demo, a freely distributed demonstration or preview of a computer or video game
*
Demo mode, a feature often found in consumer electronics
*
Technology demo
**
Software Prototyping
*
Demo (comics) ''Demo'' (comics), a comic book series
*
Demo (computer programming), a kind of non-interactive multimedia presentation
*
Demo (zsnes) _Demo_, co-author of Zsnes, an SNES emulator
See also
*
Demolition
*
Demonstration
{{disambig}}
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simple:Demo
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sv:Demo
'''DEMO''' is a proposed experimental
nuclear fusion reactor. It will build upon the research that is to be conducted by
ITER, only that it will be at the scale of a commercial reactor. It may or may not generate
electricity for a public
Electric power transmission grid, depending on its success.
Image:DEMO.PNG centre|500px
How the reactor will work
:''See also:
nuclear fusion''
When
deuterium and
tritium fuse, two
atomic nucleus nuclei come together to form a
helium nucleus (an
alpha particle), and a high energy
neutron.
:
There are two technological barriers that DEMO will attempt to overcome; that first the nuclei need to be convinced to fuse, and then the energy liberated needs to be somehow utilised.
*The activation energy for fusion is so high because the
protons in each nucleus will tend to strongly repel one another, as they each have the same positive
Elementary charge charge. Nuclei must be within 1
femtometre (1 x 10
-15 metres) of each other to fuse - achieved by high temperatures.
*High
temperatures give the nuclei enough energy to overcome their
electrostatic repulsion. This requires temperatures in the region of 100,000,000
°C - achieved by using energy from
microwaves and
ion beams.
*At these tempeatures, any containment vessel would melt, so the
Plasma (physics) plasma needs to be kept away from the walls - achieved using
magnetic confinement.
*Magnetic confinement further
pressure compresses the plasma, slightly increasing the energy of nuclear collisions - '''fusion occurs'''.
Once fusion has begun, high
energy neutrons will pour out of the plasma, not affected by the intense magnetic fields (see
neutron flux). Since it is the neutrons that receive most of the energy from fusion, it is they that will be the fusion reactor's source of energy output.
*The
tokamak containment vessel will have a thick inner-coating of liquid
lithium.
*Lithium readily absorbs high speed neutrons to form further helium and tritium.
*The helium and tritium rejoin the plasma, and the remaining lithium suffers a subsiquent temperature increase.
*This increase in temperature is passed onto (compressed) liquid
water in a sealed pipe. The presence of a localised hotspot in the pipe sets up a
convection current.
*The convection current will be used drive the turbine of a generator, to create an
electrical current - '''useful energy'''.
{{fusion power}}
Category:Fusion reactors
Category:Big Science
Category:Alternative energy
it:DEMO
a demo for
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