[en] The EAST tungsten divertor was designed and manufactured in 2012-2014 shut down. First commissioning is during EAST 2014 plasma summer operation due May to July. Some weak points exposed and brought damages on some divertor modules. Reasons were analyzed and optimization was made. Around half year spent for analysis, divertor modules structure optimized manufacturing and reconstruction. The optimized divertor operated during 2015 summer plasma operation and demonstrate optimizations are efficiency. There is no issue for tungsten divertor during operation. EAST plasma heating power increased step by step and will up to 20MW in 2015 winter campaign plasma operation and will validate tungsten divertor heat exhausting capability. (author)

[en] The passive stabilizers loop (PSL) is part of the plasma stabilizing system built in the EAST. Its purpose is to provide passive feedback control of the plasma vertical instability on short time scales. To accommodate with the new stage for high performance plasma and enhance the control of vertical stabilization in EAST, the project of PSL has been carried out. The eddy currents are induced by the vertical displacement events (VDEs) and disruption. The distribution of the eddy currents depend on the structure of the PSL and the formation of the induction. The FE model is created and meshed by the ANSYS software. Base on the simulation of plasma VDEs and disruption, the distribution and decay curve of the eddy currents on the PSL are obtained. The stress and the strain caused by the eddy currents and the magnetic fields are calculated. (author)

[en] The EAST upper divertor was updated to tungsten divertor in 2014, but the lower divertor was still left carbon divertor. The upper divertor heat load exhausting capability can be up to 10MW/m² , but only 2MW/m² for the lower divertor. To meet the device high performance plasma operation and high plasma heating power. The lower divertor planed to be updated to tungsten divertor. The lower tungsten divertor concept design started from 2016. Considering plasma configurations, neuter particles exhausting, field expansion, cost reduction and so on, geometry of lower divertor was optimized and will be different from upper tungsten divertor geometry.

[en] Full text: EAST is the first full superconducting tokamak equipped to actively cooled plasma facing components (PFCs) which design and assembly were firstly finished in May 2008. During the two experiment campaigns in 2008 and 2009, the in-vessel components with full graphite tiles as first wall had been operated successfully. However, in some cases, fast particles have been observed, which locally increased power flux density, leading to damage of some of PFCs and other in-vessel components, and also for the reason of electromagnetic force. In view of safety operation with actively-cooled PFCs for handling of large input power over long pulse discharge, some R and D and maintenance were accomplished to improve the in-vessel components are presented here. For the purpose of large plasma current (1 MA) operation, the previous separate up and down passive stabilizers in low field were proposed to be electrical connected to stabilize plasma in the case of vertical displace events (VDEs). The design and activation work are described in this paper. (author)

[en] In-vessel components are important parts of EAST superconducting tokamak. It is include plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structure design, analyses and related R and D had been completed. Divertor is designed as up down symmetric to accommodate both double null and single null plasma operation. Passive plates can supply around 100ms time constant during plasma vertical movements. In-vessel coils are used for plasma vertical movements active control. Each cryo-pumps can supply around 45m³/s pumping speed for particle exhaust. Analyses shows when 1MA plasma current disrupt in 3ms EM loads caused by halo current will not bring unacceptable stress on divertor structure. Bolted divertor thermal structure can sustain 2MW/m² up to 60s operation if plasma facing surface temperature is limited to 1500 deg. C. Thermal testing and structure optimised testing have been made to demonstrate the analyses result. (author)

[en] The differential acceleration between a rotating mechanical gyroscope and a nonrotating one is directly measured by using a double free-fall interferometer, and no apparent differential acceleration has been observed at the relative level of 2x10^-6. It means that the equivalence principle is still valid for rotating extended bodies, i.e., the spin-gravity interaction between the extended bodies has not been observed at this level. Also, to the limit of our experimental sensitivity, there is no observed asymmetrical effect or antigravity of the rotating gyroscopes as reported by Hayasaka et al

[en] EAST is a full superconducting tokamak, The main parameters have been described in many other papers. It has been complete assembly and vacuum test started from end of January. Although all of the TF coils and most of the PF coils have been tested their superconducting performance in testing facility the device will still be cool down to test all cryogenic system, TF coils and PF coils without vacuum vessel ports. All the ports, divertor and other in vessel components will be installed after cool down test. EAST divertor is up down symmetric to supply possibility operate both single null and double null plasma configuration. The geometry of the divertor is based on simulations using the B2-EIRENE Monte Carlo code. The reference configuration for the EAST divertor is an inner vertical target, an outer vertical target with an open private flux region and a dome below the X-point. The vertical target is inclined so as to intercept the magnetic field lines of the separatrix at an acute angle, giving deep inboard and outboard channels in which expect to establish a partially detached plasma regime. In this regime, while the plasma remains attached in the outer region of the SOL, the plasma is detached from the PFCs in the region near the separatrix causing the power profile to broaden and power to be radiated to other surfaces. Together with the lower end of each vertical target and dome forms a -V- cross-section that confines neutral hydrogenic particles in the divertor channels aids partial plasma detachment and particle exhaust. The plasma facing material for EAST divertor is a doped graphite developed in China. CuCrZr heat sink with cooling channels are bolted to stainless steel supports. Graphite tiles are bolted to heat sink with graphite foil improve thermal contact. In-vessel cryo-pumps are both install behind dome and outer vertical target for particles exhaust. EM loads bring by eddy current and halo current have been considered in divertor structure design and analyses. Different input plasma heating power has been considered in thermal analyse. (author)

[en] An improved terrestrial experiment to test the equivalence principle for rotating extended bodies is presented, and a new upper limit for the violation of the equivalence principle is obtained at the level of 1.6x10^-7, which is limited by the friction of the rotating gyroscope. This means that the spin-gravity interaction between the extended bodies has not been observed at this level

[en] EAST superconducting tokamak aims at >400s high-performance H-mode operations with a full metal wall and a divertor steady-state heat load of ~10MW/m² , demonstrating the physics basis of the Chinese Fusion Engineering Test Reactor (CFETR), the next-generation tokamak currently under R&D in China. Divertor heat exhaust and particle control is one of the keys for achieving long-pulse H-mode operations.

[en] Full text: Technical R&D is essential for optimized design of the EAST lower tungsten divertor planning to finish assembly in the mid-term of 2019. This poster presents the most urgent technical R&D work that had been recently finished or is expected to be launched in the near-future. In order to improve quality control of contact or welding bond between the armour and the heat-sink of the divertor prior to its installation into the vacuum vessel, a non-destructive examination method by transient infrared thermography is being developed and had been applied to test the lower graphite strike target. To likely use the Mo material in the lower heat flux area, the structure of Mo tile with bolt was tested by electron beam testing facility. The result shows the structure can sustain the heat flux of more than 2.5 MW/m² . Later, a welding structure using resistance welding with solder method is being carried out to raise the capacity of heat flux and increase the interface strength. To eliminate the weld lines between CuCrZr plate and 316L tubes, a new explosive welding method manufacturing the hollow plate of a typical CuCrZr/316L heat-sink plate will replace other welding methods like HIP, laser or electron beam. The explosive welding structure manufactures basically through the process of milling the groove, filling the mould and the explosive welding, and analyzes the interface by mechanical shearing, bending test, bond interface analysis and SEM scanning, and then tests the pressure resistance of flow paths within. To find a more economic or a new method to fabricate the tungsten flat tile or monoblock structure, the explosive welding and direct bonding differ from the HIP method is being studied. The explosive welding of tungsten is an innovation method relies on brittle ductile transition theory of tungsten and suitable constraint of specimen in the explosive process. The direct bonding method without using interlayer metals is used to construct the metallurgical interface directly between Cu and W and make the tensile strength of Cu/W bond close to the Cu.