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Toward Steady-state High Performance Discharges: EAST Starts a New Phase of Experiments
JIANGANG LI
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Toward Steady-state High Performance Discharges:
EAST Starts a New Phase of Experiments

JIANGANG LI
INSTITUTE OF PLASMA PHYSICS, CHINESE ACADEMY OF SCIENCE

The Experimental Advanced Superconducting Tokamak (EAST) is the first fully superconducting tokamak which was approved by the Chinese government in July 1998. Its mission is to conduct fundamental physics and engineering research on advanced tokamak fusion reactors with steady, safe and high performance, in order to provide a scientific base for experimental reactor design and construction. Construction started in October, 2000. Assembly was finished at the end of 2005 and commissioning was completed in March 2006. During the next 10 years of construction of ITER, EAST, together with KSTAR, JT-60SA and WEST tokamaks, will be an important experimental test bench for conducting ITER related steady-state advanced plasma science and technology research.

A series of experimental techniques to create long pulse plasma discharges has been developed at EAST in recent years, and up to 400 s divertor plasma and 30 s H-mode has been obtained at EAST. In 2012 upgrades were carried out. EAST ports were closed Monday, May 19, signaling the 2014 kickoff of the first round of the EAST experiment campaign, after a nearly 20-month-long upgrading break since September 2012.

Tremendous efforts have been made during the past two years to enhance EAST's capabilities; nearly every subsystem except the superconducting magnets has been upgraded or modified to enable higher performance and truly steady state operation. In the coming experiment, the Academy of Sciences, Institute of Plasma Physics (ASIPP) hopes that EAST can realize high performance steady-state operation of over 400s plasma duration, which is also one of ITER's future scientific targets.

The major upgrades include the following:

1. H&CD systems have been upgraded around 30MW, namely 4 MW CW 2.45GHz and 6MW 4.6GHz LHCD systems, 12MW CW ICRF system with wide band frequency of 24-70MHz, 4MW 50-80keV NBI system. The 2nd 4MW NBI and 2MW ECRH of 140GHz could be ready in October.

2. 78 different diagnostics have been installed, and all key profiles of plasma parameters will be provided during the coming experiments.

3. The upper divertor has been changed into an ITERlike W monoblock configuration with up to 10 MW/m2 heat removing capacity.

4. Top and bottom internal crypumps have been installed with a 160 M3/s pumping speed.

5. 16 ITER-like RMPs coils together with several other new ELM mitigation methods, such as supersonic beam injection, CW Li&D2 pellet injectors, gas puffing from different target places, and up to 1kHz power modulation of H&CD systems (LHCD, ICRF, NBI, ECRH) have been implemented.

6. 2 ITER-like VS coils have been installed to better control plasma vertical displacements.

7. Fast control power supply and plasma control system have been upgraded to facilitate the control of high plasma performance discharges.

8. Other systems, such as the PF&TF power suppliers, cryogenic system, cryogenic transmission line, HTc superconducting current leads and fueling systems have also been upgraded towards more reliable operation condition.

Fig. 1: Experimental Advanced Superconducting Tokamak (EAST).

EAST starts pump-down. The plasma operation is expected at the end of June after a successful cooling down and a full commissioning of all upgraded sub-systems. The coming campaign will be completed around the end of July. The major task of the campaign is to tune each and every sub-system well so that they perform with a high reliability and availability, to establish a solid technical base for the next campaign. Over 100s H-mode is foreseen in this campaign. The 2014 EAST second experiment is planned to start from October, when the second NBI and ECRH are ready, and last until the end of January 2015. As always, EAST is open to all world fusion communities. Calls for experiments proposals will be sent out in early September with a list of detailed machine capabilities and diagnostics. We look forward to working with our international partners to achieve exciting results on EAST.

Fig. 2: EAST internal plasma phase component structure.

JIANGANG LI is the Director of Institute of Plasma Physics, Chinese Academy of Science (ASIPP). He has worked in the field of fusion research for nearly 30 years. His main efforts have focused on plasma wave interaction, plasma wall interaction and tokamak operation. He has led the HT-7 physics experiments since 1996. He joined the EAST project beginning with its construction in 1998 and has led its experimental program since 2006. For past few years he has concentrated on advanced steady-state operation in EAST, the activities of the Chinese ITER home team, and the Chinese next step fusion development activities. He is the chair of Chinese fusion advisory committee and member of ITER council.

 
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