first engineering commissioning of east tokamak
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First Engineering Commissioning of EAST Tokamak
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2006 Plasma Sci. Technol. 8 253
(http://iopscience.iop.org/1009-0630/8/3/01)
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Plasma Science & Technology, vo1.8, No.3, May 2006
First Engineering Commissioning of EAST Tokamak*
WAN Yuanxi (zz,%), L1 Jiangang (3&WIJ), WENG Peide ($jm@), EAST team
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
Abstract Experimental Advanced Superconducting Tokamak (EAST) is the first fully super- conducting tokamak. The first commissioning started on Feb. lSt of 2006 and finished on March 30th of 2006 at the Institute of Plasma Physics, Chinese Academy of Sciences. It consists of leakage testing at both room temperature and low temperature, pumping down, cooling down all coils, current leads, bus bar and the thermal shielding, exciting all the coils, measuring magnetic con- figuration and warming up the magnets. The electromagnetic, thermal hydraulic and mechanical performance of EAST Toroidal Field (TF) and Poloidal Field (PF) magnets have also been tested. A l l sub-systems, including pumping system, cryogenic system, PF& TF power supply systems, magnet instrumentation system, quench detection and protection system, water cooling system, data acquisition system, main control system, plasma control system (PCS), interlock and safety system have been successfully tested.
Keywords: tokamak, supercoducting magnet, test PACS: 52.55.Fa, 85.25.L
1 Introduction The EAST superconducting tokamak['], a national
project approved and financed by the Chinese gov- ernment, is an advanced steady-state-capable experi- mental device for high temperature plasma research. Its purpose is to establish a scientific and technolog- ical basis for next geneation tokamak reactor in the future. The EAST tokamak comprises 16 D-shaped toroidal field coils[2], 14 poloidal field coils[3], current leads and superconducting bus-lines, vacuum vessel, thermal shields, cryostat, divertor and in-vessel com- ponents. The main sub-systems are as follows, a. A 2 kwl4.5 K cryogenic system[4], which provides
supercritical helium to cool magnets, bus-lines, current leads, shields and support;
b. Pumping and fueling system15]; c . Power supply and quench protection for TF sys-
d. Power supply and quench protection for PF sys-
e . Control and instrumentation system for all the
f. Plasma heating and current drive system; g. Plasma diagnostic system; h. Control and data acquisition system; i. Electricity, compressed air, and the deion water
systems. After a working period of nearly 7 years, includ-
ing 2 years of R&D, by the beginning of 2005, almost all of superconducting magnets were manufactured and testedLg]. Then EAST assembling was started and fin- ished by the end of 2005. Fig. 1 and Fig. 2 show its panorama.
The EAST commissioning was started on Feb. 1, 2006 and finished on March 30, 2006. The main purpose of the EAST first commissioning consists in testing the EAST device and its subsystem's engineering perfor-
tem [61 ;
tem [7,8l;
magnets;
Fig.1 Top view before the installation of cryostat
Fig.2 EAST bird-view
mance and capabilities, exploring the reliable scenarios for plasma operation, acquiring the key technical pa- rameters of both the device itself and its sub-systems as well as validating the reliability of the interlock, safety and protection system. Total 260 shots have been en- ergized. The longest TF current duration was 5000 seconds and the highest TF current was 8200 A, cor- responding to an intensity of the toroidal field of 2 T. All the testing results showed that the EAST device and its sub-systems are successfully built.
* supported by the National Meg-Science Engineering Project of the Chinese Government
2 Main results of the commis- sioning
a. Pumping system started on Feb. 7 and was suc- cessfully operated through whole commissioning pe- riod. The lowest vacuum in cryostat reached 3.8 X
IOw5 Pa that was below the operating requirement of 2 X 1 0 - ~ Pa.
b. The 2 kwl4.5 K cryogenic system was put into op- eration on Feb. 10 and the device's cooling down started on Feb. 18. All of the coils (215 ton cold mass totally) were cooled down to 4.5 K on March 4. The test record is shown in Fig. 3. The cryogenic system was optimized and reached to its designed state. The mass flow rate in each cooling channel was above the design value. The power of refrigerator reached 2.4 kWl4.5 K. c. 4 sets of PF power supply systems and TF power
supply system were connected to different coils and have been tested successfully. The results showed that the systems are reliable. d. Main control system, data acquisition system,
plasma control system (with the help of GA colleagues, USA), the interlock and'safety protection system were tested. The systems met the requirement of commis- sioning operation.
e. The magnet instrumentation was tested. The re- sults of both the temperature and coil resistance mea- surements showed to be reasonable. The 87 joint re- sistances were below 10nR, which met the design and operation requirements.
f. All the coils were energized with different currents and ramping rates. Individual coil, including two dif- ferent PF coils, 4 PF coils, 4 PF with TF coils have been tested. The longest TF duration of 5000 seconds is shown in Fig. 4 with a highest TF current of 8200 A, corresponding to an intensity of the toroidal field of 2 T, and the highest PF current ramping rate was 20 kA/s. A total 260 shots have been operated for quench test- ing, joint resistance and magnetic configuration mea- surements.
g. Quench detection and magnetic diagnostic ob- tained large amount of data which were very useful in getting reliable quench protection and magnetic con- figuration for setting a reliable data base for internal components installation in near future.
h. 18 copper current leads and 8 High Temperature Superconducting (HTS) current leads worked properly and passed the testing.
i. A few problems were found, indicating the fur- ther efforts should be made for the completion of the construction of EAST.
1) One minor leakage has been found during cooling down with 0.6 Mpa pressure in the cryostat thermal shield cooling circuit, which is acceptable for the future operation. However it has been fixed in April.
2) The isolation level dropped from the design value of 5 kV to 1 kV after connecting the instrumentation wires to the cryostat feed-through and connecting the superconducting bus bar to the current leads. This will be solved out soon. Efforts should be made for getting the isolation level at above 5 kV.
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Plasma Science & Technology, v01.8, No.3, May 2006
1 L Cmldavn of TF magneb
Tlma
Fig.3 The cooling down of magnets
~ ~
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,~~,~~~~~,4~ ?.$ ** *.$*e ****,.'* $*+*,i.* +:e+ ;.",-**;*.$*
& & & ~ & & ~ ~ ~ ~ ~ ~ ~ ~ ~ a ~ &"P Fig.4 Wave form of TF coil current charge
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3) One turbine in cryogenic system was damaged which need a replacement within two month as re- quired.
In summary the first engineering commissioning of EAST tokamak was done successfully with the param- eters as shown. The device will start operation in 2006.
References 1 Wan Y X, Weng P D, Li J G, et al. "Progress of the
EAST Project in China". 21th International Atomic Energy Agency (IAEA) Fusion Energy Conference, 2004
2 Chen W G, Pan Y-N, Weng P D, et al. The supercon- ducting tokamak HT-7U and its Magnet system. The International Conference on Nuclear Date for Science and Technology, Tokai, Japan, 2003
3 Wu Weiyue, Li Baoseng, Zhu Ning. Design of the PF system for EAST(HT-7U) tokamak. 20th IEEE NPSS Symposium on Fusion Engineering, San Diego, CA USA, Oct. 2003, 436 N 439
4 Bai Hongyu, Bi Yangfang, Wang Jingrong, et al. Design of 2 kW/4K Helium Refrigerator for HT-7U. 19th International Crygenic Engineering Conference (ICEC), Gre:oble, France, 2002. 183 N 186
5 Gu X M, WANG Xiaoming, QIN Pingjiaa, et al. Plasma Science & Technology, 2000, 2(6): 557
6 Liu Xiaoning, Jiang Jiafu, Liuwei Xu, et al. Nucl. Fusion, 2006, 46: 90 N 93
7 Fu P, Song Z Q, et al. Nuclear Fusion, 2006, 46: 85 N
89 8 Fu P, Liu Z Z, et al. Fusion Science and Technology,
2002, 42(1): 1 5 5 ~ 161 9 Wu Yu, yeng Peide. Plasma Science & Technology,
2005, 7(4): 2919 N 2922 (Manuscript received 8 April 2006) E-mail address of WAN Yuanxi: [email protected]