Solar energy is any form of energy radiated by the sun, including light, radio waves, and X-rays. Thermonuclear fusion is the energy producing process which takes place continuously in the sun and stars. Nuclear fusion is a nuclear reaction in which - PowerPoint PPT Presentation


Title: Solar energy is any form of energy radiated by the sun, including light, radio waves, and X-rays. Thermonuclear fusion is the energy producing process which takes place continuously in the sun and stars. Nuclear fusion is a nuclear reaction in which


1
(No Transcript)
2
NUCLEAR FUSION
  • Solar energy is any form of energy radiated by
    the sun, including light, radio waves, and
    X-rays. Thermonuclear fusion is the energy
    producing process which takes place continuously
    in the sun and stars. Nuclear fusion is a nuclear
    reaction in which nuclei combine to form more
    massive nuclei with the simultaneous release of
    energy. The combining of the different protons
    leads to the formation of a new element. In the
    core of the sun at temperatures of 10-15 million
    degrees Celsius, Hydrogen is converted to Helium
    providing more than enough energy to sustain life
    on earth.
  • Regions of the sun include the core,
    radiation zone, convection zone, and photosphere.
    Gases in the core are about 150 times as dense as
    water and reach temperatures as high as 16
    million degrees. Nuclear fusion of the hydrogen
    atoms takes place in the core.

3
  • Fusion is what happens when two atomic nuclei
    are forced together by high pressure ... high
    enough to overcome the strong repulsive forces of
    the respective protons in the nuclei. When the
    nuclei fuse, they form a new element, and release
    excess energy in the form of a fast-moving
    neutrino and a positron. The energy is 'extra'
    because the mass of the newly formed nucleus is
    less than the sum of the masses of the original
    two nuclei the extra mass is converted to energy
    according to Einstein's equation Emc2 This
    energy can be used to do useful work!
  • The main fusion reaction involved occurs between
    the nuclei of the two hydrogen isotopes,
    Deuterium (D) and Tritium (T).

4
FUSION REACTION
In this drawing you can see a diagram of a
nuclear reaction between two hydrogen isotopes as
they are fused together to produce helium and a
lone neutron. Nuclear fusion actually combined
the nuclei (protons) of an element to produce a
different element. Besides neutron it also
ejects two further particles a positron (a
positively charged electron) and a strange,
almost mass-less, particle called a neutrino.
The positron and neutrino go flying off with
kinetic energy supplied by converting some of the
mass of the transmuted proton into kinetic
energy, in accordance with E mc2.
5
  • 10g of Deuterium (which can be extracted from
    500 liters of water and 15g of Tritium produced
    from 30 g of Lithium would produce enough fuel
    for the lifetime electricity needs of an average
    person in an industrialized country.

As you can see, an unbelievable amount of energy
can be produced through nuclear fusion.
Unfortunately, scientists have been unable to
find practical ways of accessing this energy. At
the temperatures required for the fusion of most
hydrogen isotopes (over 100 million degrees
Celsius!), the fuel has changed its state from
gas to plasma. Plasma is a fully ionized gas
containing approximately equal numbers of
positive and negative ions. It is an electric
conductor and is affected by magnetic fields. In
a plasma, the electrons have been separated from
the atomic nuclei.
6
  • But there's a catch! In the sun, the energy to
    force nuclei together comes from the sun's
    immense internal temperatures, approaching 16
    million degrees or more at the center! In order
    to cause nuclei to fuse here on earth they must
    either be heated to that temperature, or caused
    to move fast enough to simulate a correspondingly
    high temperature. That has been done already,
    more than 50 years ago. The energy to set off the
    fusion reaction was supplied by an atomic bomb,
    and the fusion reaction that resulted was called
    a 'hydrogen bomb'! But the energy release was all
    at once, and uncontrollable. In order for
    fusion reactions to occur, the particles must be
    hot enough (temperature), in sufficient number
    (density) and well contained (confinement time).
    These simultaneous conditions are represented by
    a fourth state of matter known as plasma. In a
    plasma, electrons are stripped from their nuclei.
    A plasma, therefore, consists of charged
    particles, ions and electrons.

7
FUSION REACTORS
  • Magnetic Confinement

Efforts to control fusion first relied on the
principle of magnetic confinement, in which a
powerful magnetic field traps a hot
deuterium-tritium plasma long enough for fusion
to begin.
In November 1997, researchers exploiting the
magnetic confinement approach created a fusion
reaction that produced 65 percent as much energy
as was fed into it to initiate the reaction. This
milestone was achieved in England at the Joint
European Torus, a tokamak facility--a
doughnut-shaped vessel in which the plasma is
magnetically confined. A commercial fusion
reactor would have to produce far more energy
than went into it to start or maintain the
reaction.
8
At Princeton University's plasma physics
laboratory in New Jersey, scientists have
produced a controlled fusion reaction at the
Tokamak Fusion Test Reactor there. During these
reaction the temperature in the reactor surpassed
three times that of the core of the sun.
9
  • 'Tokamak' is a Russian acronym for toroidal
    magnetic chamber. This device was first
    developed by Russian scientists. A tokamak is a
    toroidal plasma confinement device, resembling a
    doughnut in shape. The plasma is confined not by
    the material walls but by magnetic fields. The
    reason for using magnetic confinement is twofold.
    First, no known material can withstand the
    hundred-million degree temperatures required for
    fusion. Second, keeping the plasma in a magnetic
    bottle insulates it well, making it easier to
    heat up.(Such reactors are inherently safe. If
    the plasma escapes, it immediately cools down,
    and the reaction stops!)Escaping neutrons and
    energy would heat a body of water a steam
    turbine and generator would produce electricity.
    This magnetic confinement method for producing
    fusion is regarded by some scientists as the most
    promising one for future commercial energy sites.
    This stems from the way Magnetic Confinement
    fusion works, which allows for a sustained
    reaction and thus continuous energy production.
    Many 'tokamaks' are in operation currently,
    around the world, and more are planned for the
    future. But so far, none have been able to
    sustain the reaction for more than a few seconds
    ... the plasma leaks out. Improved magnet design
    and higher input power will perhaps allow these
    reactors in the future to maintain a fusion
    reaction indefinitely, producing copious amounts
    of power.

http//ippex.pppl.gov/temp/tokamak/tokamaknew.htm
10
NUCLEAR FUSION ADVANTAGES AND DISADVANTAGES
Nuclear fusion, if it can be developed, would
have several advantages over conventional fossil
fuel and nuclear fission power plants. The fuels
required for fusion reactors, deuterium and
lithium, are so abundant that the potential for
fusion is virtually unlimited. Oil and gas fired
power plants as well as nuclear plants relying on
uranium will eventually run into fuel shortages
as these non-renewable resources are consumed.
Like conventional nuclear plants, fusion reactors
have no emission of carbon dioxide, the major
contributor to global warming or sulphur dioxide,
the main cause of acid rain. Fossil fuel power
plants burning coal, oil and natural gas are
large contributors to global warming and acid
rain. One of the barriers to the widespread use
of conventional nuclear power plants has been
public concern over operational safety, and the
disposal of radioactive waste. Major accidents,
such as Chernobyl, are virtually impossible with
a fusion reactor because only a small amount of
fuel is in the reactor at any time. It is also so
extremely difficult to sustain a fusion reaction,
that should anything go wrong, the reaction would
invariably stop. Long lived highly radioactive
wastes are generated by conventional nuclear
plants these must be safely disposed of and
represent a hazard to living things for thousands
of years. The radioactive wastes generated by a
fusion reactor are simply the walls of the
containment vessel which have been exposed to
neutrons. Although the quantity of radioactive
waste produced by a fusion reactor might be
slightly greater than that from a conventional
nuclear plant, the wastes would have low levels
of short lived radiation, decaying almost
completely within 100 years. The major
disadvantages of nuclear fusion are the vast
amounts of time and money which will be required
before any electricity is generated by fusion.
Fusion produces no greenhouse gases but will not
be able to contribute to reducing carbon dioxide
emissions until close to the middle of the next
century. If the world does nothing and waits for
fusion as the solution to the global warming
problem, it may well be too late. Similarly,
every dollar spent on nuclear fusion would have a
much greater impact on reducing global warming if
it was spent on reducing the demand for
electricity. There are dozens of ways to reduce
electricity use through efficiency improvements
and conservation efforts, which are much less
expensive than producing more electricity through
nuclear fusion. Development of other electricity
supply technologies, such as photovoltaic cells
which convert sunlight directly into electricity,
could also eliminate the need for fusion before
it is operational.
11
In short words...
Nuclear Fusion Cons . Usually high activation
energy . High temperatures are needed for most
reactions . Hard to control in a given space and
even harder to maintain for any significant
amount of time . Very expensive
Nuclear Fusion Pros . Vast new source of
energy . Fuels (mostly hydrogen) are plentiful
. Inherently safe since a malfunction results in
a rapid shutdown . No atmospheric pollution
leading to acid rain or "greenhouse" effect .
Radioactivity of the reactor structure, caused by
neutrons, decays rapidly and can be minimized by
careful selection of low-activation materials.
Provisions for geological time-span disposal is
not needed
12
COLD FUSION
Cold Fusion is a nuclear fusion reaction of
deuterium at or relatively near room temperature.
It is still questionable as to whether or not
this is possible, although the ability to produce
this magnitude of energy at such low temperatures
would definitely be desirable.
Nuclear fusion can produce energy when the nuclei
of lighter elements come together (fuse),
creating larger nuclei. Energy is liberated when
the total mass of the end products is slightly
less than the mass of the lighter nuclei going
into the process, with that difference in mass
being converted to energy via Einstein's famous
Emc2 relationship. Because the protons in
nuclei are all positively charged, and like
charges repel, nuclei need some convincing to get
them to fuse. That convincing ordinarily involves
high temperature and pressure, such as exists at
the core of a star or under conditions created by
a fission bomb. Cold fusion is an attempt to
get fusion to occur under less extreme
conditions, possibly as a result of chemical
reactions. Despite the flurry of publicity
several years ago, cold fusion remains unrealized
speculation for now.
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Title: Solar energy is any form of energy radiated by the sun, including light, radio waves, and X-rays. Thermonuclear fusion is the energy producing process which takes place continuously in the sun and stars. Nuclear fusion is a nuclear reaction in which


1
(No Transcript)
2
NUCLEAR FUSION
  • Solar energy is any form of energy radiated by
    the sun, including light, radio waves, and
    X-rays. Thermonuclear fusion is the energy
    producing process which takes place continuously
    in the sun and stars. Nuclear fusion is a nuclear
    reaction in which nuclei combine to form more
    massive nuclei with the simultaneous release of
    energy. The combining of the different protons
    leads to the formation of a new element. In the
    core of the sun at temperatures of 10-15 million
    degrees Celsius, Hydrogen is converted to Helium
    providing more than enough energy to sustain life
    on earth.
  • Regions of the sun include the core,
    radiation zone, convection zone, and photosphere.
    Gases in the core are about 150 times as dense as
    water and reach temperatures as high as 16
    million degrees. Nuclear fusion of the hydrogen
    atoms takes place in the core.

3
  • Fusion is what happens when two atomic nuclei
    are forced together by high pressure ... high
    enough to overcome the strong repulsive forces of
    the respective protons in the nuclei. When the
    nuclei fuse, they form a new element, and release
    excess energy in the form of a fast-moving
    neutrino and a positron. The energy is 'extra'
    because the mass of the newly formed nucleus is
    less than the sum of the masses of the original
    two nuclei the extra mass is converted to energy
    according to Einstein's equation Emc2 This
    energy can be used to do useful work!
  • The main fusion reaction involved occurs between
    the nuclei of the two hydrogen isotopes,
    Deuterium (D) and Tritium (T).

4
FUSION REACTION
In this drawing you can see a diagram of a
nuclear reaction between two hydrogen isotopes as
they are fused together to produce helium and a
lone neutron. Nuclear fusion actually combined
the nuclei (protons) of an element to produce a
different element. Besides neutron it also
ejects two further particles a positron (a
positively charged electron) and a strange,
almost mass-less, particle called a neutrino.
The positron and neutrino go flying off with
kinetic energy supplied by converting some of the
mass of the transmuted proton into kinetic
energy, in accordance with E mc2.
5
  • 10g of Deuterium (which can be extracted from
    500 liters of water and 15g of Tritium produced
    from 30 g of Lithium would produce enough fuel
    for the lifetime electricity needs of an average
    person in an industrialized country.

As you can see, an unbelievable amount of energy
can be produced through nuclear fusion.
Unfortunately, scientists have been unable to
find practical ways of accessing this energy. At
the temperatures required for the fusion of most
hydrogen isotopes (over 100 million degrees
Celsius!), the fuel has changed its state from
gas to plasma. Plasma is a fully ionized gas
containing approximately equal numbers of
positive and negative ions. It is an electric
conductor and is affected by magnetic fields. In
a plasma, the electrons have been separated from
the atomic nuclei.
6
  • But there's a catch! In the sun, the energy to
    force nuclei together comes from the sun's
    immense internal temperatures, approaching 16
    million degrees or more at the center! In order
    to cause nuclei to fuse here on earth they must
    either be heated to that temperature, or caused
    to move fast enough to simulate a correspondingly
    high temperature. That has been done already,
    more than 50 years ago. The energy to set off the
    fusion reaction was supplied by an atomic bomb,
    and the fusion reaction that resulted was called
    a 'hydrogen bomb'! But the energy release was all
    at once, and uncontrollable. In order for
    fusion reactions to occur, the particles must be
    hot enough (temperature), in sufficient number
    (density) and well contained (confinement time).
    These simultaneous conditions are represented by
    a fourth state of matter known as plasma. In a
    plasma, electrons are stripped from their nuclei.
    A plasma, therefore, consists of charged
    particles, ions and electrons.

7
FUSION REACTORS
  • Magnetic Confinement

Efforts to control fusion first relied on the
principle of magnetic confinement, in which a
powerful magnetic field traps a hot
deuterium-tritium plasma long enough for fusion
to begin.
In November 1997, researchers exploiting the
magnetic confinement approach created a fusion
reaction that produced 65 percent as much energy
as was fed into it to initiate the reaction. This
milestone was achieved in England at the Joint
European Torus, a tokamak facility--a
doughnut-shaped vessel in which the plasma is
magnetically confined. A commercial fusion
reactor would have to produce far more energy
than went into it to start or maintain the
reaction.
8
At Princeton University's plasma physics
laboratory in New Jersey, scientists have
produced a controlled fusion reaction at the
Tokamak Fusion Test Reactor there. During these
reaction the temperature in the reactor surpassed
three times that of the core of the sun.
9
  • 'Tokamak' is a Russian acronym for toroidal
    magnetic chamber. This device was first
    developed by Russian scientists. A tokamak is a
    toroidal plasma confinement device, resembling a
    doughnut in shape. The plasma is confined not by
    the material walls but by magnetic fields. The
    reason for using magnetic confinement is twofold.
    First, no known material can withstand the
    hundred-million degree temperatures required for
    fusion. Second, keeping the plasma in a magnetic
    bottle insulates it well, making it easier to
    heat up.(Such reactors are inherently safe. If
    the plasma escapes, it immediately cools down,
    and the reaction stops!)Escaping neutrons and
    energy would heat a body of water a steam
    turbine and generator would produce electricity.
    This magnetic confinement method for producing
    fusion is regarded by some scientists as the most
    promising one for future commercial energy sites.
    This stems from the way Magnetic Confinement
    fusion works, which allows for a sustained
    reaction and thus continuous energy production.
    Many 'tokamaks' are in operation currently,
    around the world, and more are planned for the
    future. But so far, none have been able to
    sustain the reaction for more than a few seconds
    ... the plasma leaks out. Improved magnet design
    and higher input power will perhaps allow these
    reactors in the future to maintain a fusion
    reaction indefinitely, producing copious amounts
    of power.

http//ippex.pppl.gov/temp/tokamak/tokamaknew.htm
10
NUCLEAR FUSION ADVANTAGES AND DISADVANTAGES
Nuclear fusion, if it can be developed, would
have several advantages over conventional fossil
fuel and nuclear fission power plants. The fuels
required for fusion reactors, deuterium and
lithium, are so abundant that the potential for
fusion is virtually unlimited. Oil and gas fired
power plants as well as nuclear plants relying on
uranium will eventually run into fuel shortages
as these non-renewable resources are consumed.
Like conventional nuclear plants, fusion reactors
have no emission of carbon dioxide, the major
contributor to global warming or sulphur dioxide,
the main cause of acid rain. Fossil fuel power
plants burning coal, oil and natural gas are
large contributors to global warming and acid
rain. One of the barriers to the widespread use
of conventional nuclear power plants has been
public concern over operational safety, and the
disposal of radioactive waste. Major accidents,
such as Chernobyl, are virtually impossible with
a fusion reactor because only a small amount of
fuel is in the reactor at any time. It is also so
extremely difficult to sustain a fusion reaction,
that should anything go wrong, the reaction would
invariably stop. Long lived highly radioactive
wastes are generated by conventional nuclear
plants these must be safely disposed of and
represent a hazard to living things for thousands
of years. The radioactive wastes generated by a
fusion reactor are simply the walls of the
containment vessel which have been exposed to
neutrons. Although the quantity of radioactive
waste produced by a fusion reactor might be
slightly greater than that from a conventional
nuclear plant, the wastes would have low levels
of short lived radiation, decaying almost
completely within 100 years. The major
disadvantages of nuclear fusion are the vast
amounts of time and money which will be required
before any electricity is generated by fusion.
Fusion produces no greenhouse gases but will not
be able to contribute to reducing carbon dioxide
emissions until close to the middle of the next
century. If the world does nothing and waits for
fusion as the solution to the global warming
problem, it may well be too late. Similarly,
every dollar spent on nuclear fusion would have a
much greater impact on reducing global warming if
it was spent on reducing the demand for
electricity. There are dozens of ways to reduce
electricity use through efficiency improvements
and conservation efforts, which are much less
expensive than producing more electricity through
nuclear fusion. Development of other electricity
supply technologies, such as photovoltaic cells
which convert sunlight directly into electricity,
could also eliminate the need for fusion before
it is operational.
11
In short words...
Nuclear Fusion Cons . Usually high activation
energy . High temperatures are needed for most
reactions . Hard to control in a given space and
even harder to maintain for any significant
amount of time . Very expensive
Nuclear Fusion Pros . Vast new source of
energy . Fuels (mostly hydrogen) are plentiful
. Inherently safe since a malfunction results in
a rapid shutdown . No atmospheric pollution
leading to acid rain or "greenhouse" effect .
Radioactivity of the reactor structure, caused by
neutrons, decays rapidly and can be minimized by
careful selection of low-activation materials.
Provisions for geological time-span disposal is
not needed
12
COLD FUSION
Cold Fusion is a nuclear fusion reaction of
deuterium at or relatively near room temperature.
It is still questionable as to whether or not
this is possible, although the ability to produce
this magnitude of energy at such low temperatures
would definitely be desirable.
Nuclear fusion can produce energy when the nuclei
of lighter elements come together (fuse),
creating larger nuclei. Energy is liberated when
the total mass of the end products is slightly
less than the mass of the lighter nuclei going
into the process, with that difference in mass
being converted to energy via Einstein's famous
Emc2 relationship. Because the protons in
nuclei are all positively charged, and like
charges repel, nuclei need some convincing to get
them to fuse. That convincing ordinarily involves
high temperature and pressure, such as exists at
the core of a star or under conditions created by
a fission bomb. Cold fusion is an attempt to
get fusion to occur under less extreme
conditions, possibly as a result of chemical
reactions. Despite the flurry of publicity
several years ago, cold fusion remains unrealized
speculation for now.
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