DIII-D research program

Summary The DIII-D tokamak is uniquely positioned to contribute to the development of Magnetic Fusion Energy over the next decade. Recent stability and confinement improvements resulting from current profile control and the discovery of the VH-mode stress the importance of non-inductive current drive. The DIII-D program plan calls for the implementation of high rf systems for such profile control; localized heating and current drive for improved to tokamak performance and advancing divertor research under current drive conditions. Funding levels will determine the potential impact of this $400 M research facility by determining the pace for implementation of rf and divertor upgrades as well as determining the amount of experimental operating time. A strong DIII-D program can effectively address the R&D issues of next generation tokamaks and allow the large number of DIII-D collaborators to explore new ideas to advance the tokamak to a commercially attractive energy option.     

Tritium in the DIII-D carbon tiles

The amount of tritium in the carbon tiles used as a first wall in the DIII-D tokamak was measured recently when the tiles were removed and cleaned. The measurements were made as part of the task of developing the appropriate safety procedures for processing of the tiles. The surface tritium concentration on the carbon tiles was surveyed and the total tritium released from tiles samples was measured in test bakes. The total tritium in all the carbon tiles at the time the tiles were removed for cleaning is estimated to be 15 mCi and the fraction of tritium retained in the tiles from DIII-D operations has a lower bound of 10%. The tritium was found to be concentrated in a narrow surface layer on the plasma facing side of the tile, was fully released when baked to 1000°C, and was released in the form of tritiated gas (DT) as opposed to tritiated water (DTO) when baked.     

BEPCII事件定时系统

北京正负电子对撞机重大改造工程(BEPCⅡ)的定时系统主要包括用于产生各种触发信号和时钟信号的事件定时部分,以及储存环主频和注入器主频的锁相部分,其中前者的研制基于事件系统模块.本文介绍BEPCⅡ事件定时系统的结构和基本功能、任意Bucket选择的设计和实现、以及定时系统的总体性能.     

BEPCII直线加速器定时系统

北京正负电子对撞机升级改造工程BEPCII的重要组成部分--直线加速器于2006年7月通过了所内预验收,其中定时系统是全新建造的基于EVG/EVR的事件定时系统[1],于2006年3月起投入运行,为直线加速器的电子枪、微波激励源、能量倍增器、正电子源、调制器、BPM等设备提供精确的时序触发信号.本文介绍直线加速器定时系统的研制、安装调试、运行和改进等工作情况.     

DIII-D Program Results and Future Plans

This paper summarizes recent research results and future plans for the DIII-D National Fusion Program. The full set of transparencies for this presentation can be found at http://fusion.gat.com/pubs-ext/presentations/Stambaugh_FPA00.pdf     

Electron cyclotron heating power supplies on DIII-D

The electron cyclotron heating system on DIII-D has been supporting experiments with six gyrotrons. The gyrotrons are connected to three power supplies: two have single modulators, each energizing two gyrotrons, while the third has three modulators that can energize three gyrotrons asynchronously. However, only two gyrotrons can be run synchronously due to the limitation of the high voltage dc power supply providing the input voltage to the modulators. These two configurations mimic proposed architectures of power systems for multiple gyrotron systems and demonstrate their advantages or disadvantages, which will be discussed in more detail. A fourth power system is being built as part of an upgrade to eight gyrotrons. The two future gyrotrons will have depressed collectors. A 1.2 MW gyrotron will be delivered in mid-2011 and the design of a 1.5 MW gyrotron has been initiated. This fourth power supply will have two modulators to independently energize the cathode of each gyrotron. Commercially available high voltage amplifiers will provide the body voltage. It will also have a solid-state crowbar instead of an ignitron crowbar. This power supply is described in more detail, as well as the testing performed on the solid-state crowbar to prove its performance.     

新型快速的Blue—LED快时间探测器标定系统

为了能够连续有规律的监测宇宙线广延大气簇射（ＥＡＳ）阵列快时间探测器和电子学系统各部分的性能随时间的变化，羊八井宇宙线ＥＡＳ实验使用了一套由ＣＡＭＡＣ－ＤＡＣ，ＴＫＯ－Ｂｕｆｆｅｒ，Ｂｌｕｅ－ＬＥＤ和ＬＥＤ－ａｍｐ构成的快时间探测器标定系统，该标定系统的速度快，易于扩展，引起的数据采集系统的死时间少，对于３０ＴｅＶ以上的空气簇射事例，羊八井二期阵列的角分辨可达０．５°，此外它还能监测光电倍频管周围     

CSNS电源磁测时序控制系统

电源磁测时序控制系统能够提供磁铁在运行过程中电源控制设备和磁铁测量设备所需要的时序触发信号和同步时钟信号,该系统的准确性和稳定性对于整个磁测显得极为重要。论文介绍了基于Xilinx系列FPGA硬件电路设计、电光-光电转换电路的设计、串口通信驱动模块和LabVIEW-EP-ICS人机控制界面的实现。通过联机测试结果表明,该系统满足了电源磁测对时序控制系统的要求。     

Recent and future upgrades to the DIII-D tokamak

Research on the DIII-D tokamak focuses on support for next-generation devices such as ITER by providing physics solutions to key issues and advancing the fundamental understanding of fusion plasmas. To support this goal, the DIII-D facility is planning a number of upgrades that will allow improved plasma heating, control, and diagnostic measurement capabilities. The neutral beam system has recently added an eighth ion source and one of the beamlines is currently being rebuilt to allow injection of 5 MW of off-axis power at an angle of up to 16.5° from the horizontal. The electron cyclotron heating (ECH) system is adding two additional gyrotrons and is using new launchers that can be aimed poloidally in real-time by an improved plasma control system. The fast wave heating system is being upgraded to allow two of the three launchers to inject up to 2 MW each in future experiments. Several diagnostics are being added or upgraded to more thoroughly study fluctuations, fast ions, heat flux to the walls, plasma flows, rotation, and details of the plasma density and temperature profiles.     

Custom open source solutions for DIII-D data acquisition and control systems

Computer based control and data acquisition systems have long played a critical role in fusion research in the development and operation of experiments such as the DIII-D tokamak in San Diego. These systems require great flexibility in being able to control and tie together the many diverse subsystems that make up a tokamak, including power, cryogenic, vacuum, electrical, water, heating and computers. For well over a decade the DIII-D control and data acquisition systems have been running on Linux-based commodity computing hardware. This has provided DIII-D with a continual path of improvement to computing performance and capability while maintaining the usefulness and productivity of numerous custom developed software applications written over the years. The flexibility provided by these Linux based systems has allowed DIII-D to continue to utilize and support legacy CAMAC hardware in addition to incorporating newer PLC and data acquisition hardware. A number of in-house developed tools and applications have made these systems highly customizable and easily expandable in being able to meet the specific and growing needs of the DIII-D research program. Among the latest improvements to these systems have been upgrades to user interfaces, development of new control capabilities and increases to data acquisition capabilities. This paper will describe in detail the present state of the DIII-D computer based control and data acquisition systems and recent improvements that have been made.     

Design of Synchronous Trigger Timing System Based on FPGA

<正>Synchronization pulse trigger signal with multi-channel independently adjustable in sequential systems is used to drive electron gun,modulator,and microwave power amplifier of accelerator,and keep its working synchronously.The traditional trigger is mainly composed of signal source and analog circuits with separation element,which has the deficiency such as low precision,poor tunability and vulnerability.     

基于SOPC技术的EAST定时与同步系统

定时与同步系统是托卡马克装置实现等离子体放电流程实时控制的基础。基于SOPC技术研制的EAST分布式定时与同步系统可为各子系统提供精确时钟和同步触发信号,使装置各子系统按照预先设定好的流程运行,实现EAST等离子体放电实验时序的精确控制。EAST定时与同步系统的时序精度高于1μs,可以满足当前EAST实验的需要。     

A New Timing System for the Stanford Linear Collider

In order to be able to meet the goals of the Stanford Linear Collider, a much more precise timing system had to be implemented. This paper describes the specification and design of this system, and the results obtained from its use on 1/3 of the SLAC linac. The functions of various elements are described, and a programmable delay unit (PDU) is described in detail.     

基于频率-时间转换的精密时序控制系统的研究

介绍了基于频率-时间转换原理的精密时序控制系统,可以产生长达800μs的时间间隔,并且时间分辨为20ps,抖动小于25ps RMS.该系统采用了DDS技术和USB接口.     

光纤在合肥同步辐射装置新时序系统定时信号传输中的应用

本文讨论一种利用高速光纤传输定时精度，低重复率触发信号的方法，此方法在两相邻定地脉冲的时间间隔加入周期脉冲，在接收端剔除叠加的周期脉冲，检出定时脉冲，解决了由于光接收器低端截止频率高于定时脉冲频率的矛盾。     

EAST分布式定时同步系统的实现

分布式定时同步系统在国家大科学工程EAST中有重要作用,它用于同步EAST各子系统精准投入实验的时序。分布式定时同步系统利用PXI工业级设备并结合虚拟仪器技术实现定时同步系统,可提供1 Hz～80 MHz频率的参考时钟信号,产生1 ms～6 872 s延迟触发信号（精度达10 ns）。该系统能采集信号,并能根据检测的信号实时触发相应处理机制。分布式定时同步系统精度高且运行稳定可靠,已成功应用于2010年秋季EAST放电实验。     

Effects of resonant magnetic perturbations on radial electric fields in DIII-D tokamak

Gyrokinetic simulations of DIII-D tokamak equilibrium find that resonant magnetic perturbation (RMP) drives a neoclassical non-ambipolar electron particle flux, which causes a rapid change of equilibrium radial electric fields consistent with experimental observations during the suppression of the edge localized mode (ELM). The simulation results provide a support for the conjecture that RMP-induced changes of radial electric fields lead to the enhanced turbulent transport at the pedestal top during the ELM suppression (Taimourzadeh et al 2019 Nucl. Fusion 59 046005). Furthermore, gyrokinetic simulations of collisionless damping of zonal flows show that resonant responses to the RMP decrease the residual level of the zonal flows and damp the geodesic acoustic mode.