Wanjing Wang

Design and Test Results for the PF Power Supply System of EAST

Abstract The EAST superconducting tokamak is an advanced steady-state experimental device built at the Institute of Plasma Physics, Chinese Academy of Sciences between 2000 and 2006. This paper describes the poloidal field EAST power supply. The configuration and design of the power supply and its operation scenario are presented. A unit test and whole power supply test results are also discussed in detail.

NONDESTRUCTIVE TESTING OF EAST W/Cu DIVERTOR COMPONENTS

Abstract Recently, the EAST W/Cu divertor components, including the ITER-like monoblock W/Cu units and flat-type W/Cu units, have been developed by Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) in collaboration with Advanced Technology and Materials Co., Ltd. (AT&M). To detect the bonding quality in these multiple layer geometry W/Cu plasma-facing components (PFCs) at each step of their manufacture, special nondestructive testing techniques have been researched and developed. For monoblock W/Cu PFCs, the bonding at both W-Cu and Cu-CuCrZr interfaces was qualified by spiral ultrasonic testing (UT) with a focus probe, which was inserted into the CuCrZr tube with a flexible driving tube. Artificial defects with defined size have been measured by UT and compared with the results of high heat flux testing (HHFT). The HHFT demonstrated that the monoblock W/Cu mock-up qualified by this UT has withstood 1000 cycles of heat load at 10 MW/m2. The bonding quality of flat-type W/Cu mock-ups has also been inspected by the usual water-gap UT. The results from HHFT at 5 MW/m2 demonstrated that the present UT was unreliable for the quality control of the flat-type W/Cu PFCs.

A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system

Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.

Thermal strain measurement of EAST tungsten divertor component with bare fiber Bragg grating sensors

Fiber Bragg Gratings (FBGs) have been widely used in the sensor field to monitor temperature and strain. However, the weak mechanical property of optical fibers and insufficient heat-resistant property of general optic-fiber sensors have prevented it from being widely used, such as in some extreme engineering situations. In this work, a bare FBG sensor system had been introduced to measure thermal strain of an Experimental Advanced Superconducting Tokamak tungsten divertor component under baking condition. This strain measurement system had withstood as high temperature as 210 °C and finished the measurement experiment successfully. Meaningful measurement results had been obtained and analyzed, which showed the applicability of such a bare fiber grating sensor system and as well contributed to studying on tungsten divertors thermal strain conditions.

CFD Simulation of Hydrodynamics of Three-Dimensional Circulating Fluidized Beds with EMMS Model

Unlike the conventional drag models which were developed on the basis of experiments with homogeneous system, energy minimization multi-scale (EMMS) drag model takes into account the heterogeneous structure inside the gas-solid flow. In this paper, the transient three-dimensional full-loop gas-solid flow in a pilot scale circulating fluidized bed (CFB) with six cyclones was simulated in the computational particle fluid dynamics (CPFD) method, based on EMMS. Particle volume fraction distribution, time averaged pressure profile, and averaged particle vertical velocity were analyzed and presented. The results show that under the simulation condition, in the dense region, particles agglomerate and form clusters; pressure drop evaluation of the dense region is still far away from the experimental data but better than using Wen-Yu model; vertical velocity profile shows core-annulus structure.