Results 1 - 10 of 10
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[en] The structure of the straps on new type of ICRH antenna for EAST tokamak was introduced. Based on the calculation of the condition in which straps would work, the work temperature distribution of the straps could be obtained. Using this result, the straps resistance to thermal load and its influent on the strap structure under the operation condition are simulated. It is demonstrated that the radiation surface temperature and overall structure strength of the straps under the real thermal load (0.2 MW) satisfy the design requirements. (authors)
[en] This paper presents the design and fabrication of a Lamb wave device based on ZnO piezoelectric film. The Lamb waves were respectively launched and received by both Al interdigital transducers. In order to reduce the stress of the thin membrane, the ZnO/Al/LTO/Si3N4/Si multilayered thin plate was designed and fabricated. A novel method to obtain the piezoelectric constant of the ZnO film was used. The experimental results for characterizing the wave propagation modes and their frequencies of the Lamb wave device indicated that the measured center frequency of antisymmetric A0 and symmetric S0 modes Lamb wave agree with the theoretical predictions. The mass sensitivity of the MEMS Lamb wave device was also characterized for gravimetric sensing application. (semiconductor devices)
[en] The Faraday shield is one of the important components in the ion cyclotron resonance frequency (ICRF) heating antenna of EAST. In the physical experiment process, the Faraday shield which is located in the vacuum chamber facing plasma, will endure high heat loads. In consideration of the structural safety of the Faraday shield of EAST ICRF antenna, the thermal analysis for the actively cooled tube of the Faraday shield was performed using the finite element method (FEM) under different cooling water velocities. The results of temperature distribution on the Faraday shield tube under different water velocities were presented and studied. Then the structural analysis for the Faraday shield cooled tube was done applying the thermal-structural coupling method. The results of stresses and displacements on the Faraday shield tube under different water velocities were obtained and studied. Results of the stresses and displacements on the Faraday shield cooled tube will provide theoretical guidance for physical experiments in the future. In addition, the structure of the Faraday shield cooled tube was optimized, and the same analyses were performed for the new Faraday shield tube using the identical methods under the same conditions. Results of the analysis demonstrate that the new Faraday shield tube is better than the original one, and will provide theoretical guidance for the optimization of Faraday shield cooled tube in the future. The methods of analysis will also give a useful reference for the other similar devices. (authors)
[en] The electrical analysis was carried out for the vacuum feedthrough of EAST ICRF antenna. The electric field distribution, the electric potential distribution as well as the voltage stand wave ratio (VSWR) varying with the heating frequencies were obtained. Results of analysis demonstrate the design feasibility and rationality of the vacuum feedthrough, and provide a theoretical basis for assessing the electric characteristic of the vacuum feedthrough. In addition, the identical methods were applied to perform the electrical characteristic analysis for a new structure of the vacuum feedthrough under the same conditions. Results of analysis demonstrate that the new structure of vacuum feedthrough is better than the original structure of vacuum feedthrough. (authors)
[en] By means of numerical method, the magnetic field strength on cryostat feed-through (CFT) busbars for TF magnet at different plasma scenarios was calculated, in order to get the maximum electromagnetic loads. Finite element mechanical analysis was performed to know the stress and deformation of CFT under different working conditions. The results show that the proposed CFT structure with gimbals is properly designed, which can withstand all the electromagnetic, thermal and mechanical loads expected during operation. (authors)
[en] Residual stress is an important factor affecting the sensitivity of piezoelectric micromachined microphone. A symmetric composite vibrating diaphragm was adopted in the micro electro mechanical systems piezoelectric microphone to decrease the residual stress and improve the sensitivity of microphone in this paper. The ZnO film was selected as piezoelectric materials of microphone for its higher piezoelectric coefficient d 31 and lower relative dielectric constant. The thickness optimization of piezoelectric film on square diaphragm is difficult to be fulfilled by analytic method. To optimize the thickness of ZnO films, the stress distribution in ZnO film was analyzed by finite element method and the average stress in different thickness of ZnO films was given. The ZnO films deposited using dc magnetron sputtering exhibits a densely packed structure with columnar crystallites preferentially oriented along (002) plane. The diaphragm of microphone fabricated by micromachining techniques is flat and no wrinkling at corners, and the sensitivity of microphone is higher than 1 mV Pa−1. These results indicate the diaphragm has lower residual stress. (paper)
[en] A passive stabilization loop (PSL) has been designed and manufactured in order to enhance the control of vertical instability and accommodate the new stage for high-performance plasma at EAST. Eddy currents are induced by vertical displacement events (VDEs) and disruption, which can produce a magnetic field to control the vertical instability of the plasma in a short timescale. A finite element model is created and meshed using ANSYS software. Based on the simulation of plasma VDEs and disruption, the distribution and decay curve of the eddy currents on the PSL are obtained. The largest eddy current is 200 kA and the stress is 68 MPa at the outer current bridge, which is the weakest point of the PSL because of the eddy currents and the magnetic fields. The analysis results provide the supporting data for the structural design.
[en] In this study, we describe a novel strategy to design and construct POSS-modified silane layer on carbon fiber (CF) to strengthen the interfacial adhesion and anti-hydrothermal aging behaviors of CF-reinforced copoly(phthalazinone ether sulfone)s (PPBES). POSS was first modified by 3-aminopropyltriethoxysilane (APS) to improve chemical reactivity. Without separation and purification, APS-c-POSS was used to functionalize CF to improve reactivity and ensure the covalent linkages between CF and POSS-modified silane layer. CF coated with POSS-modified silane layer was obtained by in situ hydrolysis of APS-c-POSS. FTIR and XPS confirmed the chemical bonds between CF and POSS-modified silane layer. Dynamic contact angle, dynamic wetting test and AFM tests demonstrated that POSS-modified silane coating can increase the wettability and roughness, which could improve interlaminar shear strength and flexural strength of CF/PPBES composites by 17.5 and 30.0% with slight enhancement on tensile strength of CF. The failure mechanisms of CF/PPBES composites with and without POSS-modified silane layer were both investigated by SEM in detail. Moreover, this layer was helpful to dynamic mechanical property and hydrothermal resistance of CF/PPBES composites. This study provides alternate strategy to modify CF with POSS, which will significantly broaden the application field of POSS in advanced composites.
[en] Radio frequency (RF) heating in the ion cyclotron range of frequencies (ICRF) is one of the primary auxiliary heating methods for EAST. The ICRF system provides 6 MW power in primary phase and will be capable of 10 MW later. Three 1.5 MW ICRF systems in a frequency range of 25 MHz to 70 MHz have already been in operation. The ICRF heating launchers are designed to have two current straps with each driven by a RF power source of 1.5 MW. In this paper a brief introduction of the ICRF heating system capability in EAST and the preliminary results in EAST are presented. (magnetically confined plasma)
[en] Single-layer and double-layer polyurethane (PU) matrix coatings containing spherical carbonyl iron (SCI) and flaky carbonyl iron (FCI) were designed and prepared by using a simple and effective manufacturing method, and the thickness of the coatings was kept at 1.5 mm. The complex permittivity, complex permeability and absorption properties of the coatings were investigated in the frequency range of 2–18 GHz. The results indicate that all the single-layer and double-layer coatings exhibit excellent absorption properties and wide absorption bands. By optimizing the filler radio and coating structure, the optimal reflection loss (RL) value can reach − 35 dB at 8.6 GHz and make the widest absorption band reach 15.5 GHz (2.5–18.0 GHz) and 4.9 GHz (10.7–15.6 GHz) for RL < − 5 dB and RL < − 10 dB, respectively. The coatings of SCI/FCI/PU exhibit a broad effective absorption bandwidth, which can be effectively applied to radar signature reduction and electromagnetic interference suppression in military and civil fields.