Техническое чтение для энергетиков. Бухарова Г.П. - 11 стр.

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13
for heating deuterium gas. This is done electrically. When an electric current is
passed through a gas it sets up an electric discharge in it, with a corresponding rise in
temperature. A hollow vessel – either ring-shaped or tube-shaped, and usually made
of aluminium – is partly encircled by a huge electromagnet which produces the field
that heats up the deuterium inside. But if the hot gas touched the walls of the vessel
they would melt, and the gas would cool down; therefore, it must be kept in the
centre. This is done by another intense magnetic field around the gas, usually by
winding an electrically charged cable around the vessel. In this way the gas, which
tries to resist that 'pinch effect', is prevented from behaving about like an angry snake
as soon as the current is switched on and the temperature rises.
Zeta, the British assembly which was originally built at the atomic research
establishment, had a ring-shaped form; the 'pyrotfon
1
, set up at the University of
California, was designed as a linear tube with a special 'mirror' effect: the magnetic
field was made much stronger at either end so that the 'plasma', as the gas in the
machine is usually called, assumed the shape of a sausage – thick in the middle and
pinched at the ends. This arrangement had the effect of a magnetic mirror; the
particles racing around in the plasma were reflected back from both ends into the
centre, which increased the temperature and also the probability of the particles
bumping into each other to achieve fusion. Another American fusion research
instrument did away with the magnetic coils, and used a layer of accelerated electrons
instead for the production of the necessary magnetic field.
When one of the scientists' teams working with these machines achieves
genuine fusion – a temperature of up to 500 million degrees Centigrade may be
needed to start a thermonuclear process which can maintain itself–the question of
how a thermo-nuclear power station could work will become topical. As in a
conventional power station, coal-fired or atomic, the heat could be used to produce
steam for the turbo-generators. But by that time there may be a better and more direct
way of turning heat or radio-activity into electricity.
There are several basic systems of doing this. One, called the 'thermionic
converter', uses the principle of the cathode-ray tube in which electrons, particles of
negative electricity, are given off by a hot strip of metal, the cathode, in a vacuum.
The heat necessary to produce this effect could be that generated in a nuclear reactor;
the greater the temperature difference between the cathode, or 'emitter', and the
anode, or 'collector', the greater will be the yield of electrons and therefore of electric
current. There is, at least theoretically, no reason why a nuclear power station should
not be operating on this principle once the technological problems have been solved.
Atomic as well as conventional power stations may be made much more
efficient by the gas-blast system of generating electricity. It is based on the fact that a
blast of very hot gas (at least 2,000° Centigrade), which could be produced by a
fission or fusion reactor, becomes an electrical conductor and generates current when
moving through the poles of a powerful magnet. American and British research
laboratories are working on this scheme, but the principal problem is that of finding
materials which can withstand such temperatures for any length of time.
Another system – which might be better suited for smaller, mobile electricity

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