250MHz固态功率放大器的设计

固态功率源代替真空管功率源设备是目前射频功率源系统的发展趋势。本文介绍了一台工作在250 MHz的固态功率放大器模块的设计过程。放大器模块使用荷兰恩智浦半导体公司生产的BLF578XR型号晶体管,并且采用传输线匹配和集总元件匹配相结合的方式进行设计。通过理论计算得到匹配网络的初始值,并利用ADS(Advanced Design System)软件对匹配电路进行仿真和优化。测试结果表明,该功率放大器模块输出功率达到了850 W,功率增益达到了26 d B,功率附加效率达到60%。结果表明,该设计完全达到了系统设计要求的性能指标,并具有较强的实用性。     

固态微波放大器的开发

2．5kW／352MHz无条件稳定的微波固态放大器在意大利Legnaro国家实验室研制成功并通过测试。该放大器由9个350W推挽工作方式的功率模块构成，每个模块采用1个环形器和1个终端电阻作为保护装置。该放大器为独立相位超导直线加速器的中β超导腔提供微波功率而开发，具有高效率、线性度好、可靠性高以及低成本的特点。文章介绍了该放大器的技术特点和测试结果。     

An S-band solid-state radio frequency power amplifier used at Shanghai soft X-ray FEL facility

In this paper, we present the general design methods and parameter measurements of a 1-kW solid-state radio frequency (RF) power amplifier at 2856 MHz, for the soft X-ray free electron laser facility. Three-stage amplification with a 4-way combination is used. An RF switch module is integrated with the solid-state RF power amplifier to convert the continuous wave (CW) signal into pulse signal, with adjustable pulse width. The power gain is measured at 57.7 dB at 60 dBm output. The RF phase noise, which is measured by the low-level RF system, is﹤0.015 degree (RMS), while the pulse frontier jitter is﹤5 ns.     

田湾核电站失去两路厂外电源试验实施及方案优化

针对田湾核电站1号和2号机组带功率调试阶段失去两路厂外电源试验,文章详细介绍了该试验的前期准备工作、试验的进程和试验结果,以及发现问题的优化方案.     

应急撤离模拟在核电厂道路方案优化中的应用北大核心CSCD

将概率风险评价方法应用于核电厂的应急撤离模拟,利用自主编写的简化撤离模拟程序,结合厂址事故源项、人口、道路、气象条件等特征,对多个核电厂应急撤离条件下公众与工作人员可能的受照剂量和风险进行了对比分析。在此基础上,结合霞浦厂址应急道路方案遇到的实际问题,在保证事故应急状态下公众和工作人员能够有效撤离的同时,对应急道路方案进行了比选,为工程的实施提供借鉴和参考。相关程序和方法也可为后续发展海岛核电、小型供热堆等提供技术支持,有助于更直观地开展核电公众沟通。     

CPLD在HIRFL-CSR电源控制模块中的应用

介绍了一种采用复杂可编程逻辑器件（CPLD）实现HIRFL—CSR电源控制模块中单片机外围电路的方法，将低位地址锁存、地址译码、数据总线、分频电路、比较、计数以及逻辑电路集成于一片CPLD．大大缩小了印制板的面积并提高了系统可靠性．同时，由于CPLD的现场可编程性，使整个系统的灵活性显著增强。     

Increasing the power of the high temperature reactor module

To alleviate the economic problems of the modular pebble bed high temperature reactor, its design was modified in such a way that the power output was increased from 200 to 350 MWth. The core geometry was changed from cylindrical to annular, and the pressure vessel diameter was increased to 6.7 m. Control rods are placed in both the outer reflector and the graphite central column. In a safety analysis, loss of heat sink, loss of coolant and water ingress accident were examined. Reactor shutdown and decay heat removal take place passively, and the maximum fuel temperature stays theoreticallybelow 1600 °C, implying full retention of the fission products in the fuel elements. The central column has a diminishing effect on the positive reactivity effect of water ingress. A cost analysis shows that the specific investment costs of a four-module plant would decrease by 26% and the electricity generating costs would reduce by 19%.     

Design optimization of first wall and breeder unit module size for the Indian HCCB blanket module

The Indian test blanket module(TBM) program in ITER is one of the major steps in the Indian fusion reactor program for carrying out the RD activities in the critical areas like design of tritium breeding blankets relevant to future Indian fusion devices(ITER relevant and DEMO).The Indian Lead–Lithium Cooled Ceramic Breeder(LLCB) blanket concept is one of the Indian DEMO relevant TBM,to be tested in ITER as a part of the TBM program.Helium-Cooled Ceramic Breeder(HCCB) is an alternative blanket concept that consists of lithium titanate(Li_2TiO_3) as ceramic breeder(CB) material in the form of packed pebble beds and beryllium as the neutron multiplier.Specifically,attentions are given to the optimization of first wall coolant channel design and size of breeder unit module considering coolant pressure and thermal loads for the proposed Indian HCCB blanket based on ITER relevant TBM and loading conditions.These analyses will help proceeding further in designing blankets for loads relevant to the future fusion device.     

Venturi tube application in high power test of the SRF module

In the superconducting RF module, the dissipation power of the niobium cavity is an important parameter. In the Superconducting radio frequency (SRF) module’s acceptance test at Shanghai Synchrotron Radiation Facility (SSRF), the Venturi tube is used to measure the quality factor of SRF cavity at 4.2 K. During the test, the venturi tube is be calibrated by increasing heat load with internal heater. In this paper, the horizontal test principle and venturi effect are briefly introduced. The authors find out a...     

核反应堆棒控电源电路仿真与优化

棒控电源是核电站反应堆燃料棒的驱动机构的电源,核电站内的棒控电源柜通常与驱动机构相距较远,通过电缆相连接。为了提高设备的集成度,棒控电源柜中多个直流斩波模块共用一个整流模块,这种设计大大增加了直流母线的长度。直流母线和电缆的分布电感和分布电容,会产生电压过冲、增加开关损耗、产生高频振荡,并对电源控制产生巨大干扰。通过对电源电路的分析,计算直流母线的分布电感和电缆的分布电容,建立棒控电源系统PSIM仿真模型,得到了与样机测试波形近似的仿真结果。然后提出了减小直流母线分布电感的优化方法,经理论推导和仿真验证,可有效改善高频振荡和电压过冲等问题,显著提高电路性能指标。     

Performance and modelling of 70kVdc power supply with solid-state crowbar

The experimental activities of tokamak research involve development of high power RF and microwave sources for fusion related heating and current drive applications. High power RF and microwave tubes like Klystron, Gyrotron and Tetrode are in general operated with high voltage DC power supplies. These HVDC power supplies of the order of 70 kVdc, must be equipped with necessary arc fault protection in addition to general over current and over voltage protection.The arc fault protection must act within few microseconds to prevent permanent damage to the RF tube, window, etc. When an arc fault is detected, output voltage of the DC power supply is short circuited using a crowbar device (generally Ignitron, Thyratron, thyristor, rail-gap, etc.) that operates in few microseconds. This diverts the fault current from the load to crowbar device, thereby protecting the load. This is necessary as conventional protection in the power supply input takes ～100 ms to switch-off. The crowbar device must be able to take the fault current till the circuit breaker placed at power supply input is switched off.The arc fault protection is tested for its effectiveness by “wire-burn” test. Full power short circuit of ～1.5 MW DC power supply puts enormous stress on the power supply, utility and the crowbar, therefore frequent wire-burn testing is to be avoided.This report presents simulation of wire-burn test using PSIM software. Optimization of the component values without conducting actual wire-burn test could be achieved.     

用于多丝漂移室读出的扇入延迟前端电子学

多丝漂移室阵列是设计中的低温高密核物质测量谱仪(Cooling storage ring External-target Experiment,CEE)上的前角带电粒子径迹探测器,信号读出的一种备选方案是采用传统前置放大器和采样幅度数字转换器(Analog-to-Digital Converter,ADC)来完成信号的放大和获取,该方案结构较简单,成本适中,而且可以处理单根丝上的多重点火信号。为了进一步降低电子学的通道数目,而又不显著影响探测器的性能,研制了一种扇入延迟电路,将漂移室上不同的多根丝信号进行扇入延迟处理,合成为一路信号后再输入到采样ADC的单个通道进行波形采样和数字化。实际的测试结果表明,该电路对信号处理产生的信号能量展宽好于1%,时间晃动好于500 ps,对应的位置分辨好于25?m,满足漂移室径迹探测器阵列对位置分辨小于300?m的要求。     

HIRFL-CSR主环磁铁电源数据采集控制模块设计

介绍了一种基于微处理器TMS320VC5402的磁铁电源电流数据采集控制模块,给出了模块的硬件组成和软件设计.经过测试表明该模块具有非常高的控制精度,处理能力强,速度快,而且集成度高,便于组成网络控制系统,现已应用于HIRFL-CSR主环六极磁铁电源控制系统中.     

Lifetime estimation of IGBT module using square-wave loss discretization and power cycling test

The Shanghai advanced proton therapy facility is a proton cancer treatment device designed and built by the Shanghai Institute of applied physics at the Chinese academy of sciences. The accelerator part comprises a proton linear accelerator (linac) injector and a circular synchrotron. An alternating current current transformer (ACCT) is used for non-intercepting beam current measurement at the drift tube linac exit. According to the beam characteristics, the ACCT is required to complete real-time beam current and pulse width measurements at currents of 3–30 mA, frequencies of 1–10 Hz, and pulse widths of 40–400 μs. In this paper, we report the design and development of an ACCT. The designed ACCT was simulated using CST Microwave Studio, and calibrated using an oscilloscope and signal generator. Variations in the output signal of the ACCT were investigated as a function of ceramic gap size, number of coil turns, and resistance. According to the simulation and experimental results, the optimal number of coil turns was found to be 30. In addition, a low-pass filter was adopted to filter the noise introduced during long-distance signal transmission using a coaxial cable with the length of 20 m. The calibration results show that the corresponding rise time of the ACCT is 800 ns with the sensitivity of 8.2 V/A and a droop of less than 1%, meeting the design requirements.

     

Experimental study of a single tube high RF power amplifier for ICRF heating system

A concept of a single tube high RF power amplifier was developed for ion cyclotron range of frequency (ICRF) plasma heating system. In the concept, a tetrode was used with a grounded cathode and input power to drive a control grid of the tetrode was provided by a switching circuit. As the new amplifier arrangement can eliminate a low power (10 kW level) and an intermediate power (100 kW level) tetrode amplifiers, their high voltage DC (HVDC) power supplies, and control and monitor system for these amplifiers and HVDC power supplies in a conventional high RF power source of the ICRF heating system, this new high RF power source is more flexible on frequency change and more mechanically reliable than the conventional one. A test amplifier composed of the tetrode and a field effect transistor (FET) switching circuit was constructed. The FET switching circuit was so compact that it could be mounted close to the tetrode socket. The maximum output RF power of 8.5 kW was obtained with a plate efficiency of 82% at 70 MHz. The feasibility of the single tube high RF power amplifier was experimentally proved. The plate efficiency of 82% could not be explained by the standard class-C amplification but by high efficiency amplification under assumptions of a flat-topped plate current pattern and double resonance of an output cavity at the fundamental frequency and the third higher harmonic frequency.