Annual Report (MS-Word)

(Annual Report to IEA)

Three Large Tokamak Cooperation

(January to December 1990)

Executive Committee

1. Cooperation Activities

Two workshops were held in 1990 as shown in Attachment 1; one at TFTR on Transport and Confinement Analysis in October, and the other at JT-60 on Current Drive & Plasma Stabilization in December. There were eleven personnel exchanges which were started in 1990 for the periods of longer than two weeks as shown in Attachment 2. Five review tours were made, in which eleven staffs participated. Reports on these activities ( Form A, B and C ) are filed in Attachment 3.

2. Meeting of the Executive Committee

The fifth Executive Committee meeting took place at Princeton Plasma Physics Laboratory on 15 and 16 March, 1990. The members were Dr. A. Gibson , Dr. J-P Poff from JET, Dr. S. Tamura, Dr. A. Funahashi from JT-60, Dr. D. Meade from TFTR, Dr. S Eckstrand from USDOE. The Committee elected Dr. Meade as Chairman until the next meeting. JAERI acted as the Secretariat, represented by Mr. H. Shirai.
The Executive Committee recommended that the Agreement be extended for another five years and selected Dr. S. Tamura as the liaison to inform the IEA of its recommendation to extend the present Implementing Agreement which ends on January 14, 1991. The present form of the Implementing agreement is adequate when the references to TFTR are modified to include a possible successor.
The Executive Committee discussed coordinated contribution to the ITER-related physics R & D tasks, and agreed that the large tokamaks will continue to make best efforts to plan their research programs and to carry out them to meet the requirements from the physics design of ITER. Along this line, each party has contributed to the ITER Conceptual Design Activity by conducting more than 10 R&D tasks out of 23 required from the ITER Design Team.
JET began to use Beryllium as a first wall material. JT-60 will operate deuterium plasma from 1991. TFTR/JET will operate with tritium in later years. The Executive Committee agreed that staff working on each other's sites would comply with local regulations and any necessary insurance cover or liability for long-term consequences would remain the responsibility of the home laboratory and employer of the staff concerned.
The plans for workshops and personnel exchanges for one and a half years were agreed upon.
The minutes of the fifth Executive Committee meeting is attached to this report. (Attachment 4)
The next meeting of the Executive Committee will be held at JET Joint Undertaking on March 21 and 22, 1991.

3. Membership of the Executive Committee

The members of the Executive Committee are as shown in Appendix 1. It was noted that one of the TFTR alternate members had been changed to Dr. R. J. Hawryluk from Dr. J. C. Sinnis and that one of the JT-60 members changed to Dr. S. Tamura from Dr. M. Yoshikawa and the JT-60 alternate members changed to Drs. H. Kishimoto and M. Azumi from Drs. S. Tamura and Y. Shimomura.

4. Status of the Three Large Tokamaks

The cooperation among the three large tokamaks has been carried our successfully. Results among the three tokamaks have been shared for deeper understanding of tokamak physics and hence the coordinated cooperation contributed much to achieve higher plasma performance in each device. The high Ti mode found in TFTR termed as supershot has been produced in H-mode plasmas in JET and L-mode plasmas in JT-60. The ICRF heating scheme was adopted in TFTR after effective central heating demonstrated in JET and JT-60. Lower hybrid current drive experiments have just begun in JET following the confinement improvement achieved in JT-60 by suppression of central MHD activity. Disruption data compiled in JET contributed to the design of a new vessel structure for JT-60U. Deuterium operation in JT-60U is planned from next July seeking the better confinement of deuterium plasmas over hydrogen confirmed both in TFTR and JET. The status and major results of the three large tokamaks are summarized below.


JET operations for 1990 were successfully completed on 5th November when a shutdown period began. The main item of shutdown work is the installation of new continuous x-point dump plates at the top and bottom of the vessel. Both dump plates will be uncooled. In addition the attachment fixtures for various elements of the carbon tile wall cladding are being strengthened to improve the resilience of the vessel to disruptions. Plasma operation is expected to recommence in the improved configuration by the end of April 1991 and continue to November 1991 when a major shutdown to install the Pumped Divertor is scheduled.


JT-60 has been shut down for upgrade since November 1989. A new vacuum vessel and new poloidal coils have superseded old ones for divertor operation up to 6 MA. The existing toroidal coils have been reassembled and graphite tiles are being installed inside the vessel. Experiments on JT-60U will start in March, 1991.


The 1990 TFTR run ( April 6 - November 3 ) had 7,800 plasma shots with neutral beam power up to 33 MW and ICRF power up to 6.3 MW. The carbon/carbon fiber composite inner wall limiter behaved well without carbon blooms up to 33 MW. Lithium pellet injection was used to provide a low Z wall coating which allowed maximum deuterium fusion reaction rates up to 1017 per second. Beam emission spectroscopy was used to measure medium scale fluctuations ( ki ~ 1 ) in the core of the plasma. Fluctuations with the properties of Alfvn waves driven by super-Alfvtic beam ions have been observed suggesting that alpha particles will drive Alfvn wave instabilities during D-T experiments. TFTR is presently shutdown to install additional limiters for the ICRF heating system, repair ICRF launchers, maintain neutral beamlines, power supplies and diagnostics. Deuterium operation is planned to resume in June 1991 with D-T operation beginning in mid-1993. All plans are subject to uncertainties since the US Magnetic Fusion budget has not been approved.

5. Contribution to the ITER physics R & D

The three large tokamaks have made best efforts to plan their research programs and to carry out them to meet the requirements from the physics design of ITER. Along this line, each party has contributed to the ITER Conceptual Design Activity by conducting more than 10 R&D tasks out of 23 required by the ITER Design Team.
Of particular contributions, which the three large tokamak made, are the impurity control by Be limiter/coated wall in JET, physical understanding on density limit, helium transport properties and exhaust characteristics in JT-60 and TFTR, scaling of energy confinement, in particular, first results for H-mode scaling initiated by JET, bootstrap current with dominant fraction in JT-60 and TFTR.
For the coming ITER Engineering Design Activity, long-term physics R&D tasks are surveyed and proposed.

6. Extension of the Implementing Agreement

The Executive Committee members discussed the process of the extension of the Implementing Agreement at the 13th International Conference on Plasma Physics and Controlled Nuclear Fusion Research held at Washington D.C. After consultation with EC members and with Mr. Yamada of IEA, the steps toward extension are being taken. Since the Implementing Agreement has been expired on January 15, 1991, the Agreement is considered to be extended provisionally until the final agreements have been made by Euratom. IEA considers the Large Tokamak Cooperation to continue in force.

Appendix 1
Executive Committee Members

Dr. A. Gibson : Associate Director and Head of Plasma Heating and Operation Department
Dr. J-P Poff : Head of Staff Office

Dr. E. Bertolini : Deputy Head of Machine and Development Department and Head of Magnet and Power Supplies Division

Dr. S. Tamura : Director, Department of Large Tokamak Research
Dr. A. Funahashi : General Manager, Diagnostics Division

Dr. H. Kishimoto : Deputy Director, Department of Large Tokamak Research
Dr. M. Azumi : General Manager, Large Tokamak Experiment Division II

Dr. D. M. Meade : TFTR Project Head, PPPL
Dr. J. W. Willis : Director, Division of Confinement Systems, Office of Fusion Energy, USDOE

Dr. R. J. Hawryluk : TFTR Deputy Project Head, PPPL
Dr. S. A. Eckstrand : Division of Confinement Systems,Office of Fusion Energy, USDOE