Optimization studies of the ITER low field side reflectometer

Microwave reflectometry will be used on ITER to measure the electron density profile, density fluctuations due to MHD/turbulence, edge localized mode (ELM) density transients, and as an L-H transition monitor. The ITER low field side reflectometer system will measure both core and edge quantities using multiple antenna arrays spanning frequency ranges of 15-155 GHz for the O-mode system and 55-220 GHz for the X-mode system. Optimization studies using the GENRAY ray-tracing code have been done for edge and core measurements. The reflectometer launchers will utilize the HE11 mode launched from circular corrugated waveguide. The launched beams are assumed to be Gaussian with a beam waist diameter of 0.643 times the waveguide diameter. Optimum launcher size and placement are investigated by computing the antenna coupling between launchers, assuming the launched and received beams have a Gaussian beam pattern.     

Analysis of the ITER low field side reflectometer transmission line system

A critical issue in the design of the ITER low field side reflectometer is the transmission line (TL) system. A TL connects each launcher to a diagnostic instrument. Each TL will typically consist of ～42?m of corrugated waveguide and up to ten miter bends. Important issues for the performance of the TL system are mode conversion and reflections. Minimizing these issues are critical to minimizing standing waves and phase errors. The performance of TL system is analyzed and recommendations are given.     

基于MEMS硅基底的L波段圆极化微带天线的研究与设计

对所设计的以硅为基底,中心频率在1.9GHz的圆极化微带天线进行了介绍.由于硅的介电常数较高,导致天线效率很低,在高频率段容易产生表面波,所以采用挖空气腔来降低相对介电常数.设计出的微带天线尺寸为55 mm×55 mm,尺寸较大,因而采用了加载和曲流技术来减小天线的尺寸.在此基础上设计出2×2天线阵列,并用HFSS进行仿真,方向图和增益均达到要求.     

某星载天线结构设计与分析

天线作为一种能接收和发射电磁波的装置,其性能在很大程度上影响着航天任务的执行效果。文中根据航天器的任务需求以及火箭发射主动段复杂的力学环境、在轨情况下的热真空环境等空间环境条件,设计了一种星载螺旋天线,并分别从结构静强度、动强度和动刚度等方面进行了力学仿真,对基频和安全裕度进行了计算。仿真结果表明产品满足抗力学环境设计要求,且试验件通过了随机振动及热真空环境试验的考核。该天线结构形式简单、可靠,便于制造,有良好的空间环境适应性,尤其是对空间极端的高低温热环境有良好的适应性,对类似星载螺旋天线的结构设计具有指导意义。     

Progress in the MITICA beam source design

In the framework of the development of the ITER neutral beam (NB) system, a test facility is planned to be built in Padova. A full size prototype of the ITER heating NB injector (MITICA) shall be built and tested at full beam power (17 MW) as per ITER requirements. The design of the MITICA beam source has further progressed following updated optimization and overall integration criteria. In the paper, the major design choices and revisions are presented, together with some results of numerical analyses carried out in order to assess the electrostatic and thermo-mechanical behaviour of the source.     

Development of a Concept of Reflectometric Diagnostics for the ITER Tokamak for Plasma Probing from the High-Magnetic-Field Side

The capabilities of the reflectometric diagnostics in the ITER facility during plasma probing from the high-magnetic-field side are investigated. This technique allows measurements of the density profile and the plasma turbulence-rotation velocity at the lower extraordinary wave from a plasma with a critical density to the center of the plasma column. The system also allows one to probe the plasma column at the ordinary wave. It is proposed to use a combined mirror–horn antenna system. Under conditions where there is limited space for placing horns, this results in a significant (up to 20 dB) increase in the signal, compared to the system of two horns considered earlier. The results of calculations on optimizing the elements of the waveguide transmission line using a two-dimensional full-wave code are presented. The possibility of employing the Doppler effect to study plasma rotation by using antennas for controlling the shape of the plasma column while performing reflectometry at the lower extraordinary wave is considered. This effect is estimated theoretically in the actual ITER plasma configuration.     

A conceptual project for a divertor monitor of the neutron yield in the ITER

The operating conditions of a neutron diagnostic system responsible for measuring the neutron yield in the ITER tokamak reactor are analyzed. Based on results of physical calculations and analysis of suitable methods for measuring the neutron yield, an original concept of a system for measuring neutron fluxed in the divertor zone of the ITER is proposed. The design for the neutron flux monitor located in the divertor zone of the tokamak is selected in view of the requirements specified for the neutron diagnostic system of the ITER and its operating conditions. Four fission chambers with different sensitivities and radiator materials are used as sensitive elements of the monitor. This system is capable of measuring neutron fluxes over the entire dynamic range of the neutron yield in the ITER with an error of ≤10% and a time resolution of 1 ms that are necessary for studying the physical mechanism of thermonuclear plasma ignition and burning. Several possible variants for housing the detector unit inside the divertor assembly and integrating it in the existing project are proposed. The problems of carrying out efficiency calibration of the divertor neutron monitor with the aim of determining the absolute value of the neutron yield in the ITER tokamak reactor are discussed.     

Progress in the conceptual development of the ITER vertical neutron collimator

Monte-Carlo calculations of the fluxes of forward and scattered neutrons at points of arrangement of the detectors for the analyzed design of the ITER multichannel vertical neutron collimator have been performed with the MCNP model. A concept of a vertical neutron collimator positioned in the diverter port is proposed, and the efficiency of its application for determining the spatial distribution of the ITER tokamak reactor’s neutron source is demonstrated with allowance for the calculation results and the possibilities of integrating the collimator into the ITER structure.     

The development of Campbell integration system applied in high particle flux measurement

Campbell Mode is a method widely used in nuclear signal processing. In this article, we introduce the design of the new system based on the Campbell integration measurement applied in NFM (neutron flux measurement) systems for ITER plasma diagnose. In this article, we introduce a digital particle flux measurement system based on Campbell integration theory. A subsequent series of experiment are conducted to test the digital Campbell system performance, which proves that the Campbell integration system is competent for the plasma diagnose in ITER.     

ITER中子屏蔽横块的模态分析与谱分析研究

为避免真空室屏蔽层受地震的影响,根据ITER中子屏蔽层结构对其中子屏蔽单元模块进行了单点响应谱分析,将中子屏蔽结构的模态分析结果与法国某地的加速度谱进行了模态叠加。分析发现,应力极值在许可应力范围之内。     

Parametric study for conductor design of KSTAR PF coils

Large superconducting magnets such as ITER (International Thermonuclear Experimental Research) or KSTAR (Korean Superconducting Tokamak Advanced Research) magnet system adopted a cable-in-conduit conductor (CICC) using a forced-flow cooling system. Main optimization criteria for the conductor design of superconducting magnet system are stability margin and CICC cooling requirements. A zero-dimensional method is applied for the calculation of stability and the conductor optimization. In order to increase conductor performance, three different strands, ITER HP-I and HP-TI, and KSTAR HP-III, are tested. The strand characteristics of KSTAR HP-III are measured in the Samsung’s PPMS and Jc measurement system, and applied for this study. Also, the strand diameters, 0.81 mm and 0.78 mm are considered for this study, due to design change. Based on this result, the proposed configuration of CICC has been fabricated.     

机载无源相控阵天线结构轻量化设计

机载雷达天线发展迅速,已从传统机械扫描天线发展为相控阵天线以及更为先进的机相扫天线。随着雷达技术的发展及电子设备集成度的提高,天线已经成为雷达系统中组成最为复杂、重量占比最大的单元,因此天线的轻量化设计是雷达结构设计的关键技术。某机载无源相控阵雷达天线组成复杂,结构紧凑,单元间距小,重量指标要求严格,结构设计难度大。文中介绍了该天线结构设计中采取的轻量化措施,包括结构布局、模块化设计、复合材料的应用等,并通过力学仿真及环境试验,对天线轻量化设计的结果进行了验证。结果表明,天线结构设计满足产品力学环境要求,设计合理,对相关产品的结构设计有一定的参考意义。     

某高机动雷达天线结构机电结合优化设计

天线设计包括电讯设计和结构设计,在两种设计都要求最优时,便产生矛盾.随着对雷达天线机动性要求的不断提高,这种矛盾愈发突出.针对某高机动雷达天线,论述了如何使用有限元分析软件(ANSYS)进行机电结合优化设计,以及介绍了与电讯设计进行交互优化的方法.这些方法有效地解决了高机动既要结构灵活轻巧又要满足电讯高指标性能两者间的矛盾,实现该雷达既要高精度又要高机动的设计要求.     

基于模块化的雷达天线结构优化设计

文中介绍了某雷达天线结构优化设计过程,针对该雷达天线安装空间的特点和相关技术要求,具体阐述了2 个方面的内容:一方面,采用模块化设计方法,将天线内设备划分成发射分机、电源监控分机、功分器组件和天线子单元4 个模块,分别对每个模块进行结构设计和热设计,解决了天线内部安装空间不足、电缆布线复杂等问题;另一方面,采用外形隐身技术,对天线骨架进行重新设计,减小了雷达散射截面积,提高了天线的隐身性能。最后通过软件仿真技术,对其隐身性、热设计及力学性能进行了分析,结果均满足设计要求。     

某球面阵列天线结构设计

球面阵列天线具有半空间乃至全空间波束覆盖能力,因而受到广泛关注。但是,球面阵列天线的结构形式比其他天线阵面更加复杂,天线阵面的切块分割更加困难,给天线阵面的布局、阵面骨架的架构、天线子阵的划分以及天线单元的结构设计等带来了很大挑战。文中从球面阵列天线结构设计需求出发,提出了一种新的天线阵面结构布局方案,并给出了阵面骨架、天线子阵、天线单元等的设计思路。通过对阵面骨架进行有限元力学仿真,初步验证了球面阵列天线结构设计的合理性,为进一步研究球形阵面骨架打下基础。     

结构功能一体化天线的机电耦合机理和实验

结构功能一体化天线能够将集成微带天线阵列的射频功能件嵌入到武器平台结构中,它既可作为力学承载的蒙皮结构,又可作为收发电磁波的微波天线,在未来武器装备中具有巨大的应用前景。这种天线具有结构和电路的高度集成以及服役环境苛刻等特点,现有方法难以满足其设计制造。文中针对结构功能一体化天线的机电耦合机理问题,提出了一类阵列天线结构因素对电性能影响的混合建模方法。结合理论分析和试验数据,建立了该类天线的机电耦合模型,发掘了典型结构因素对电性能的影响机理。通过天线样件的力电性能实验,验证了机电耦合机理的有效性。本研究成果可应用到结构功能一体化天线的设计制造领域中。     

某相控阵天气雷达结构总体设计

相控阵天气雷达是一个较复杂的系统,其布局要求紧凑,天线阵面精度要求高,组件功耗大,与其他天气雷达相比,其结构设计更复杂。文中通过总体布局设计、天线阵面结构设计与天线阵面平面精度控制以及天线座结构设计完成了某型相控阵天气雷达的设计开发工作。同时通过天线与天线座结构刚强度计算和组件热设计计算来确保设计满足要求。目前,该雷达已交付用户,其成功研制对后续类似雷达的设计具有一定的参考价值。     

Electron cyclotron emission diagnostic for ITER

Electron temperature measurements and electron thermal transport inferences will be critical to the nonactive and deuterium phases of ITER operation and will take on added importance during the alpha heating phase. The diagnostic must meet stringent criteria on spatial coverage and spatial resolution during full field operation. During the early phases of operation, it must operate equally well at half field. The key to the diagnostic is the front end design. It consists of a quasioptical antenna and a pair of calibration sources. The radial resolution of the diagnostic is less than 0.06 m. The spatial coverage extends at least from the core to the separatrix with first harmonic O-mode being used for the core and second harmonic X-mode being used for the pedestal. The instrumentation used for the core measurement at full field can be used for detection at half field by changing the detected polarization. Intermediate fields are accessible. The electron cyclotron emission systems require in situ calibration, which is provided by a novel hot calibration source. The critical component for the hot calibration source, the emissive surface, has been successfully tested. A prototype hot calibration source has been designed, making use of extensive thermal and mechanical modeling.     

稀疏阵列天线结构设计

稀疏阵列天线是一类特殊的相控阵天线,阵列稀疏技术的采用在降低造价的同时给天线结构设计带来很大困难。介绍了一种简洁的模块化稀疏阵列天线结构以及优化设计方法。     

Effects of size and shape of metallic objects on performance of passive radio frequency identification

Passive ultra high frequency (UHF) spectrum radio frequency identification (RFID) systems have numerous applications. Continuous research and development of RFID systems is carried out to study solutions for different challenging cases of identification. Metallic objects set challenges for identification due to the behavior of electromagnetic waves on conductive boundaries. Therefore, novel tag designs have been developed for identification of metallic objects. This article presents a performance comparison of two different metal-mountable tag antennas, which are printed inverted-F antenna (IFA) and microstrip patch antenna with photonic band gap (PBG) ground plane and with regular ground plane. The effects of size and shape of metallic objects on tag antenna performance are studied with read range measurements and compared between the tag antenna types.