Jet joint undertaking

European Union

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Progress report 1985
Environmental research

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• Sciences et techniques

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• Publié par: EUROPEAN-UNION
• Nombre de lectures: 40
• Langue: English
• Poids de l'ouvrage: 19 Mo

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JOINT EUROPEAN TORUS
JET
JOINT
UNDERTAKING
PROGRESS
REPORT 1985 EUR 10616 EN
EUR-JET-PR3
JET
JOINT
UNDERTAKING
PROGRESS
REPORT 1985
REFERENCE
ONLY
DAT E 2 6 LUG. 1989
MARCH 1986 Tilis document is intended for information only
and should not be used as a technical reference.
EUR 10616 EN (EUR-JET-PR3) March 1986.
Editorial work on this report was carried out by B.E. Keen
The preparation for publication was undertaken by
the Documentation Service Units, Culham Laboratory.
© Copyright ECSC/EEC/EURATOM, Luxembourg 1986
Enquiries about copyright and reproduction should be addressed to:
The Publications Officer, JET Joint Undertaking, Abingdon, Oxon. 0X14 3EA, England
Printed in England Contents
Introduction, Background and Report Summary 3
Technical Achievements During 1985 12
— Torus Systems;
— Power Supply and Magnet Systems;3
— Neutral Beam Heating System;5
— R.F. Heating System;9
— CODAS; 20
— Diagnostic Systems;4
— Remote Handling;8
— Tritium. 31
Scientific Achievements During 1985
— Plasma Optimization;
—a Position and Current Control (PPCC);
— Impurities and Radiation Losses;6
— Plasma Boundary Phenomena;9
— Instabilities and Disruptive Phenomena; 43
— R.F. Heating;5
— Energy Confinement;7
— Theory;
— Summary of JET Results.
Developments and Future Plans 51
— Separatrix Experiments;
— Control of Sawteeth Oscillations;2
— Profile Control;4
— Multi-Pellet Injection for Fuelling/Re-Fuelling;
— Density Control and Separatrix Dump Plates.6
Appendices8
I Work of Theory Division
II Task Agreements — Present Status 69
III List of Articles, Reports and Conference Papers Published, 1985 7
IV Reprints of JET Papers: 83
(a) JET-R(85)03 Low Ζ Material for Limiters and Wall Surfaces in JET: Beryllium and Carbon; 8
(b) JET-P(85)08 Impurity and Radiation Studies during the JET Ohmic Heating Phase; 101
(c) JET-P(85)10 JET Contributions to 12th European Conference on Controlled Fusion and Plasma
Physics, Budapest, Hungary 2-6 September 1985; 12
(d)5 Latest Results from JET; 235
(e) JET-P(85)18 Magnetic Topology, Disruptions and Electron Heat Transport; 251
(f) JET-P(85)20 ICRF Studies on JET; 26
(g)5 Sawtooth Oscillations; 28
(h)6 JET Contributions to the 11th Symposium on Fusion Engineering (Austin, Texas,
U.S.A., November 1985).9 Foreword
This is the third JET Progress Report which covers the As the new Director, it will be a difficult task to
second full year of JET's operation. These Progress follow such a leader as Dr Wüster, but with the
Reports were introduced in 1983 to provide a more dedication, enthusiasm and skill of all Project staff,
detailed account of JET's scientific and technical I am sure that this obstacle will be surmounted and
progress than that contained in the JET Annual we will continue to meet with confidence the
Reports. The first two Reports (in 1983 and 1984) tremendous challenges offered by the Project. Other
described the main activities and advances made on changes in the Project included that of Dr R J
JET during the relevant periods, and concentrated on Bickerton, formerly an Associate Director and Head
the scientific and technical involvement of the relevant of Scientific Department, who was appointed Deputy
JET Departments. Director and Head of Heating and Theory
These previous Progress Reports provided good Department. Also Dr M Keilhacker joined JET from
reference documents of JET developments and results IPP Garching, F.R.G., as an Associate Director and
during the early operation period, before these Head of the Experimental Department.
advances were published in the conventional literature. During 1985, the machine again provided excellent
Now, JET results receive world-wide dissemination at technical performance. The Project entered Phase IIA
international Conferences and meetings and in various of its programme devoted to additional heating studies
scientific journals, at an earlier stage. Therefore, there to observe the effects of large power ion cyclotron
is now less need for such a detailed record of all JET resonance heating (ICRH) on the plasma temperature
events, as the machine now operates almost in a routine and confinement properties. Two RF antenna had been
manner. In addition, the staff effort required for installed during the shutdown at the end of 1984, and
preparation and compilation of the text was these were used during operations in the first half of
considerable and in many cases produced a duplication 1985. From July, a four month shutdown was scheduled
of material already published. Consequently, it was to allow installation of additional components
decided to change the format of the 1985 Progress including a third RF antenna. Final preparations were
Report, so that it provided an overview summary of also completed for the first neutral injection system.
the scientific and technical advances during the year, Operations were continued until the end of the year.
supplemented by appendices of detailed contributions In 1985, there was 1446 tokamak pulses with plasma
(in preprint form) of the more important JET articles current exceeding 1 MA. This represented a consistent
produced during that year. This Report represents an increase over 69 in 1983 and 472 in 1984. Throughout
experiment in this respect, and comments from 1985, many plasma pulses were produced with the
recipients would be welcomed. maximum rated toroidal magnetic field value of 3.45T.
The document is still aimed not only at specialists A plasma current of 5 MA was reached and maintained
and experts engaged in nuclear fusion and plasma for 1 s. At present, machine operations at high currents
physics, but also at a more general scientific are restricted to plasma elongation ratios of 1,4 to avoid
community. To assist in meeting these general aims, the the possibility of damage to the machine, if control of
Report contains a brief summary of the background the vertical stability was lost. The design of new vessel
to the Project, describes the basic objectives of JET supports is nearly complete and when installed, this
and the principal design aspects of the machine. In restriction should be removed. Other modifications are
addition, since the Project Team structure was changed planned to enable the current to be maintained at 5 MA
during 1985, these changes are detailed, as it is within for longer time periods, with the possibility of
this structure that the activities and responsibilities for cautiously raising the current to higher levels.
machine operation are carried out and the scientific During 1985, RF additional heating used reached a
programme is executed. record input power of 6MW, with 15MJ of energy
1985 was marred by the sudden and untimely death, coupled to the plasma. A degradation of confinement
on 30 June, of Dr Hans-Otto Wüster, the then Director time with increasing power was observed, similar to
of the Project. We shall always be indebted to him for that seen on smaller tokamaks, but experience there
his leadership and contributions to the formation and has shown that this degradation can be reduced or
success of the Project. Many tributes to his memory avoided by operating in a mode limited with a magnetic
came from all over the world. Fusion in Europe and separatrix. This so called X-point operation has been
the world has lost a great man, but, above all, everyone demonstrated on JET with plasma currents up to
within the JET Project has lost a great friend. 1.5 MA, but not yet with additional heating, so that
1 Foreword
the beneficial effects of this mode have still to be neutral injection system for additional heating was
demonstrated on JET. installed and this will further improve the additional
heating power introduced into the plasma. Plasma impurities remained high in 1985, as
previously, and although they do not lead to a The successful construction of the device and the
significant radiated power loss from the plasma core, most encouraging results obtained so far are a tribute
they dilute the number of ions available for useful to the dedication and skill of all who work on the
fusion reactions. A combination of multiple pellet Project. They also reflect the continuous co-operation
refuelling and powerful additional heating, which will and assistance received from the Associated
be tested in 1987, are likely contenders to improve this Laboratories and from the Commission of the
situation. European Communities. They support the confidence
and guidance given to the Project management by the The scientific results so far achieved on JET are
JET Council, JET Executive Committee and JET encouraging. In terms of the plasma parameters —
Scientific Council. density, temperature and confinement — JET has
already reached the stage where each of these With such devotion from all sides, the Project faces,
parameters is within a factor of two of three of those with confidence, the many problems and challenges
needed for fusion reactor. At the end of 1985, the first that are likely to be encountered in the future.
Dr Ρ H Rebut
April 1986 Introduction, Background and
Report Summary
The studies are aimed at: Introduction
a) Investigating plasma processes and scaling l