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 A major international agreement between the European
 Community, the United States and Japan for cooperation in
 the field of research on controlled nuclear fusion is to be
 signed in Munich on 15 January 1986.  The agreement
 associates the three largest tokamak-type (1) experimental
 fusion devices in the world: JET, which has been built at
 Culham in the United Kingdom as part of the European
 Community's fusion programme, TFTR, which is installed at
 Princeton (United States),  and JT-60 at Naka-machi
 (Japan).  As described in the agreement, the cooperation
 between the three centres will take many different forms:
 more extensive exchanges of information and researchers,
 joint preparation of certain research programmes, joint
 organization of symposia, etc., it being possible to conduct
 all these activities on either a trilateral or a bilateral
 basis. =   In the current state of research, physicists
 generally  consider it more than likely for it to be in a
 tokamak that  the scientific feasibility of fusion will be
 demonstrated.   More precisely, they take the view that such
 demonstration  is possible in the large second-generation
 tokamaks such as  the European JET, the American TFTR or the
 Japanese JT-60.   This is what makes the cooperation
 agreement between these  three facilities so important:  it
 makes it possible further  to consolidate the most advanced
 concept in the nuclear  fusion field and will help speed up
 future developments. For the European Community, the
 agreement represents the  possibility of retaining and
 strengthening the position they  have gained in the
 forefront of the field by dint of twenty  years' sustained
 effort.  It is in line with the Community's  firm policy of
 international cooperation in the fusion  field, which has
 already produced a number of bilateral  agreements with
 Sweden, Switzerland and the United States.
 The agreement will be officially signed on 15 January at the
 Max Planck Institute for Plasma Physics at Garching (near
 Munich) by the respresentatives of the different
 institutions concerned:  Mr Fasella (Director-General for
 Science, Research and Development at the Commission of the
 (1) The term "tokamak" of Russian origin means "toroidal
 magnetic chamber" and describes the configuration of the
 vessel in which the fusion process takes place.
           
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 European Community) for Euratom and the JET Joint
 Undertaking, Mr Trivelpiece for the US Department of Energy
 and Mr Mori for the Japanese Atomic Energy Research
 Institute (JAERI).  The signing ceremony will be attended by
 Mrs Steeg, Director-General of the International Energy
 Agency, under the auspices of which the agreement was drawn
 up, and Mr Palumbo, Director of the Community's fusion
 programme and  Chairman of the Agency's Fusion Power
 Coordinating Committee.  It will be preceded by a welcoming
 address by Prof. Pinkau, Director of the Plasma Physics
 Institute, and followed by a press conference.
                 - - - - - - - - -
 BACKGROUND
 Controlled thermonuclear fusion is a gamble that physicists
 have for many year been endeavouring to win.  If fusion
 could be achieved in satisfactory operating conditions, it
 would constitute a virtually inexhaustible source of energy;
 such a prospect is, however, in the realm of the fairly
 distant future.  Research currently in hand throughout the
 world is merely aimed at demonstrating the scientific
 feasibility of fusion, namely the possibility of producing a
 fusion reaction with a positive energy balance, i.e., one
 that releases a greater amount of energy than that employed
 to produce it.  Once this has been demonstrated, it will
 clearly remain to be determined whether fusion reactors are
 technologically possible, economically advantageous and as
 safe to operate as they appear today.
 The sun and the stars derive the energy they release from
 nuclear fusion reactions: as their name suggests, such
 reactions consist in the fusion of two nuclei of light atoms
 to produce a heavier nucleus.  The process is accompanied by
 the release of a large amount of energy.  In order to be set
 off, it requires extreme temperature and density conditions:
 inside the sun, fusion reactions take place at a temperature
 of 15 million degrees celsius.  In order to achieve fusion
 on earth, without the aid of the extremely strong
 gravitational force of the sun, it is necessary to attain
 even higher temperatures, in the region of 100 million
 degrees.  At such temperatures, matter exists in a special
 state, called plasma: a mixture of ions (electrically
 charged nuclei) and electrons.
 The fusion reactions that appear most promisisng are those
 involving two isotopes of hydrogen:  deuterium and tritium.
 These isotopes are universally available in extremely large
 quantities: water contains deuterium, while tritium can be
 obtained from lithium, an element that occurs plentifully in
           
                     - 3 -
 the earth's crust.  Fusion of the deuterium and tritium
 nuclei produces a nucleus of helium while releasing a  high-
 energy neutron.  As in a  fission reactor, deceleration  of
 that neutron in an outer "blanket" produces heat that can
 be utilized conventionally to generate electricity.
 Two methods are currently being investigated with a view to
 achieving the deuterium-tritium fusion reaction on earth.
 The first, called inertial confinement, involves
 compressing, with the  aid of beams of laser photons or
 charged particles, a target containing the two elements in
 the solid state.  An extremely dense plasma is thus obtained
 for a very short time.  The second method - magnetic
 confinement - consists in confining, with the aid of
 magnetic fields, a less dense but extremely hot plasma for a
 longer period.  The magnetic fields act as a vessel in this
 case, for no physical container would be capable of
 withstanding direct contact with such high temperatures.
 In the context of this second method, different magnetic
 configurations have been designed and tested.  A distinction
 is drawn between "open-ended", or linear, and "closed", or
 toroidal (ring-shaped), configurations.  In the former (for
 example, "mirror machines"),  the plasma is contained in a
 long cylinder.  In the latter (which because they are
 closed, have the advantage of not posing any  particle-
 leakage problems), the plasma is confined in a  torus-shaped
 space.  Among the machines of this type, the  most promising
 and widelyd-researched concept is the  "tokamak", which was
 inaugurated some twenty years ago by  the Soviet Union
 (tokamak being an acronym for the terms  "toroidal magnetic
 chamber" in Russion).  Other systems  exist ("stellarators"
 and "pinch machines"), which are  sufficiently similar to
 the tokamak concept to be able to  benefit from progress
 made therein if they proved in  practice to be superior.
 The European Community is  coordinating and financing a
 major fusion research programme  almost exclusively devoted
 to magnetic confinement in the   toroidal configuration.
 This programme, the cornerstone of  which is currently JET,
 is chiefly concerned with the  tokamak system;  it
 nevertheless also includes research on  the two other
 toroidal configurations, namely stellarators  and pinch
machines.

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