Jul 9 – 13, 2017
Monona Terrace Community and Convention Center
US/Central timezone

Performance of the JT-60SA cryogenic system under pulsed heat loads during acceptance tests

Jul 12, 2017, 11:30 AM
Madison Ballroom AD

Madison Ballroom AD


Christine Hoa (CEA INAC-SBT)


The JT-60SA cryogenic system is the French voluntary contribution to the joint European - Japanese project JT-60SA, a superconducting tokamak currently under assembly at the Naka Fusion Institute of QST in Japan. The tokamak will achieve deuterium plasmas with typical flat top durations of up to 100 seconds. Procurement of the cryogenic system was managed by CEA. The technical specification was issued by CEA in close cooperation with F4E and QST, according to the different operating scenarios of JT-60SA. The specifications considered also the results of a dedicated R&D program at CEA, to explore the conditions for a safe and economical operation of the cryogenic system with demanding pulsed loads.
The cryoplant was contracted to Air Liquide Advanced Technologies (AL-aT), France. Most of the subsystems were manufactured in Europe, shipped to Japan and finally installed at Naka. After one year of commissioning, the acceptance tests were successfully completed in October 2016 in close collaboration between QST, F4E, CEA and AL-aT. The ownership of the plant was transferred to QST end of 2016.
The cryogenic system has different cryogenic users at various temperatures: the superconducting magnets at 4.4 K, the current leads at 50 K, the thermal shields at 80 K and the diverter cryo-pumps at 3.7 K. The cryogenic system has an equivalent refrigeration power of about 9.5 kW at 4.5 K, with peak loads up to 12 kW caused by the nuclear heating, the eddy currents in the structures and the AC losses in the magnets during cyclic plasma operation.
The acceptance test scenarios and the transitions between different operation modes were performed by automated sequences. The main results of the acceptance tests will be reported, with emphasis on the management of the challenging pulsed operation using a liquid helium volume of 7 m³ as thermal damper.

Primary author

Christine Hoa (CEA INAC-SBT)


Mr Pascal Roussel (CEA Grenoble) Dr Kyohei Natsume (QST) Dr Yoshihiko Koide (QST) Dr Antonino Cardella (F4E) Dr Valérie Lamaison (CEA IRFM STEP) Dr François BONNE (CEA/SBT) Mr Kiichi Ohtsu (QST) Dr Enrico Di Pietro (F4E) Dr Koji Kamiya (QST) Mr Jérome Legrand (AL-aT) Mr Pascal Fejoz (CEA IRFM STEP) Mr Makato Oishi (QST) Mr Vincent Pudys (AL-aT) Mr Sylvain Girard (CEA IRFM STEP) Dr Kaname Kizu (QST) Mr Yannick Fabre (AL-aT) Dr Manfred Wanner (F4E)

Presentation materials