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22C MIR In experimental reactors, Summer 1989 nuclear fusion has been Science Votes produced at 100 million degrees. with the process (up until now) burning up far more energy than it produces. Create a fusion process at everyday temperatures, however, and the possibility of unlimited, cheap energy would be opened up. On 23 March, at a press conference in Utah, two prominent chemists, Martin Fleischmann of Southampton and Stanley Pons of Utah U'niversity, announced to the world that they had discovered a simple way of stimulating fusion at room temperature. Using this method, a gallon of sea water could yield as much energy as 300,000 gallons of petrol, without atmospheric pollution or radioactive waste. This extraordinary Claim immediately provoked world-wide controversy. the use of Scientists criticised a press conference, pre-empting the usual course of publishing results in a scientific journal, which involves the scrutiny of papers by other experts. More fundamentally, scientists challenged the validity of the claims made by Fleischmann and Pons. A few researchers claimed to have reproduced the Utah results, though some of these have since retracted their claims. Most nuclear researchers reported that they could not repeat the Utah results, and rejected the audacious theoretical solution offered by the Utah team. Commenting on the controversy, the New Scientist (6 May) summarised the experiment of Fleischmann and Pons. They had claimed 'that splitting heavy water, or deuterium oxide, by passing a current through platinum and palladium electrodes had produced such an enormity of Science Notes heat that a nuclear rather than a chemical process must be responsible. The mechanism they proposed was that the electrical potential at the palladium cathode had forced deuterium ions from the heavy water into the crystal lattice of the palladium (the structure of bonds within the element palladium, which is similar to platinum). The confined conditions of the lattice were such as to cause deuterium nuclei to fuse.' Researchers at the British government's nuclear research laboratory at Harwell subjected the Utah results to careful checking, with more sensitive equipment than that available in Utah. Dr David Williams reported (Sunday Times, 7 May): 'We have spotted neither heat nor Fleischmann and Pons are sticking to their claim that their experiments produced four times more heat than they consumed. 'In bursts, the energy was much too large to be explained by chemical phenomenon.' (Independent, 10 May) Fleischmann admitted, however, that the evidence for fusion was only circumstantial. They had found no conclusive evidence of other possible by-products of a fusion reaction such as neutrons, helium, or tritium. "I have always been ready to acknowledge that our experiments may be faulty," said Fleischmann. Why, then, did he and Pons rush to publicise their untested results and speculative explanation? Behind the scientific controversy lie fierce professional rivalries, for instance between the Utah team and Steven Jones, a prominent fusion researcher at the nearby Brigham Young University. There is ruthless competition for multi-million (continued on p23) Cold fusion or hot air?
Pete Dickenson explains what nuclear fusion is.
Nuclear fusion has the potential to produce cheap, virtually limitless energy, while eliminating many of the dangers currently linked to nuclear power. Fusion is the source of the energy of the sun and the stars. In the extremely hot cores of these bodies atoms of the lightest elements (hydrogen, helium, lithium, etc) join to form heavier elements. Some mass is lost in the process and released as energy. It the same process was harnessed in a fusion reactor boundless energy could be produced Research up to now has concentrated on fusion reactions using deuterium and tritium and the common metal lithium as being of the most practical interest. If all the deuterium in 1.5 cubic kilometres of sea water was used in a fusion reactor, the energy released could be equal to that in the world's recoverable crude oil. Since there are about one-and-a-half billion cubic kilometres of sea water, the rewards for the successful development of fusion power are huge There is a simple logic about the processes which would occur in a fusion reactor. When two deuterium atoms combine, they either form a helium atom and release energy or form one tritium atom and one ordinary hydrogen atom also releasing energy. The tritium in turn combines with deuterium, again forming an isotope of helium and releasing energy. (Deuterium and tritium
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are isotopes, or particular forms.
of hydrogen, with slightly diffe-
rent masses and other proper-
ties). If lithium is introduced, it is
broken down into helium and
tritium (a process of nuclear fis-
sion) with a release of energy and
the tritium fuses with deuterium.
All the radioactive components
are thus consumed and the final
products of the whole reaction
are helium, hydrogen and huge
amounts of energy.
However, as there is a neutron
release during the reaction, the
containment vessel and exposed
equipment would become radio-
active, though probably not to
the same extent as in a fission
reactor.
Its logical simplicity does not
mean that the process is easy to
achieve in practice. Fusion can occur only between the nuclei of atoms which are brought into contact with sufficient energy to overcome the extremely high forces with which they repel each other Such conditions can bescreated at a temperature of 100 million degrees.
At this temperature substances are not only gaseous. but they exist in a state in which their atoms have been stripped of their electrons. This high energy condition of dissociated nuclei and free electrons which is found in the sun is called a plasma.
Such a plasma cannot be kept in a material container. as it would instantly vapourise the vessel. The only way yet devised ot holding a fusion plasma is by containing it within a matrix of very strong magnetic forces. The problems of holding the plasma stable at the correct temperature and extracting energy from it have yet to be solved.
Scientists in the USSR made a significant breakthrough in 1904. They were using a toroidal. or ring shaped machine within which the plasma is contined br magnetic forces, called a Tokomak. Experiments revealed higher temperatures and greater
(continued from p22) dollar government research contracts and big business sponsorship. The observation of the writer Goethe, made al the beginning of the capitalist era, has lost none of its bite: Questions of science are very irequently career questions. A •ingle discovery may make a
plasma stability than had been
achieved before. The Tokomak
approach was adopted by other
researchers it now represents the
main line of fusion research. The Joint European Torus (JET) was
opened at Culham in the UK in
1983, and a further large Toko-
mak JT-60) has been built in Japan. One measure of the progress in fusion research is called the Lawson Product or Lawson Criterion. This computes the relationship between temperature. containment tme. and plasma density: These three factors control the problem of containing the plasma in such a condition that it will yield more energy than it requires to raise the temperature (to 100 million degrees) and confine it (within powerful magnetic fields). Experiments to date have given a Lawson Product of only onetenth of that required for a posilive energy yield. If a Tokomak achieves a plasma which satisfies the Lawson Criterion, this will have proved that a fusion power station is practical in principle. In a power generating fusion reactor the neutrons emitted in the reaction would be captured in a blanket surrounding the plasma. Heat from the blanket would be used to raise steam to drive generating turbines. An alternative approach to nuclear fusion emerged in the 1970s. This relied on the focussing of laser beams on tiny pellets of deuterium and tritium in such a way that they are compressed and heated sufficiently for the fusion reaction to occur. The peak rate of power production in laser fusion power plant will be a billion billion watts. This rate is one million times greater than all man made machinery put together and is about 10 times greater than the total radiant power of the sun falling on earth. The technological challenge of laser fusion is to wrap a power plant around micro explosions of these astronomically large peak powers. But con-
man famous and lay the foundations of his fortune as citizen. Every newly observe phenomenon is a discovery; every discovery is property. Touch a man's property and his passions are immediately aroused. (Conrersations witt Eckerman, 1823).
structing such a device would
require solutions to a whole
range of technological problems.
The fuel supply for fusion reac-
cors can be regarded as cheap and plentiful. as both deuterium and lithium can be collected from the oceans.
The problems to be solved to
make economical fusion possible are not fundamentally scientific but technical. There was great confidence and hope for the derelopment of fusion power in the
1950s and 1960s when capitalism was expanding and self-confident. But since then capitalism has not seriously atrempted to harness fusion power. It will not put the resources into this area when coal. gas, and oil are still available and fission power can be used when fossil fuels run out. They are prepared to ignore the dangers of nuclear fission power shown by Chernobyl. Fusion is inherently 'cleaner' than fission because no waste nuclear fuel is left at the end of the reaction. Nevertheless, the power plant itself would be radioactive in a fusion reactor. More rescarch needs to be done to determine the extent of this risk. Neither capitalism nor Stalinism, in a period of social crisis, can be trusted to carry out balanced research into the possibilities and risks of fusion research. They prefer to rely on nuclear fission, regardless of the risks, particularly the longterm dangers of radioactive contamination and waste. Socialists must fight for safe energy production, while making it clear that the harmonious development of energy resources, possibly including fusion energy, will take place only in a socialist society.
Fleischmann and Pons.
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