HT-6M托卡马克上的超低密度实验

通过一些特殊方法,HT-6M托卡马克可以稳定运行在只带少量过热电子的超低密度(SLD)区域。其主要参数为:N_e=(0.2～0.6)×10~(13)cm~(-3);I_p=60～80kA;V_o=0.7～2.0V;B_t=0.7～1.0T;a=18cm;R=63cm。在这类放电中,等离子体的密度由限制器和壁的出气量决定,而和初始充的氢气压强完全无关。等离子体是安静的,几乎没有“锯齿振荡”。m=2,3的磁流体力学(MHD)不稳定性只出现在电流下降段。径向温度分布T_o(r)峰化,而密度分布N_e(r)是平坦的。能量约束时间τ_e为1～2ms,大约是Alcator定标律的2～4倍。     

HT-6M托卡马克上的超低密度实验

通过一些特殊方法,HT-6M托卡马克可以稳定运行在只带少量过热电子的超低密度(SLD)区域。其主要参数为:N_c=(0.2～0.6)×10~(13)cm~(-3);I_p=60～80kA;V_e。=0.7～2.0V:B_t=0.7～1.0T;α=18cm;R=63cm。在这类放电中,等离子体的密度由限制器和壁的出气量决定,而和初始充的氢气压强完全无关。等离子体是安静的,几乎没有“锯齿振荡”。m=2,3的磁流体力学(MHD)不稳定性只出现在电流下降段。径向温度分布T_e(r)峰化,而密度分布N_e(r)是平坦的。能量约束时间τ_e为1～2ms,大约是Alcator定标律的2～4倍。     

CT—6B托卡马克上的数据采集系统

本文描述了一个９００００系列多道瞬态记录仪和我们实验室开发的软件包。     

先进托卡马克概念

托卡马克堆设计是建立在今天由大托民克运行获得的充分确定的经验上的，从对这些设计的讨论人们断定，这样的堆在经济上是无吸引力的，本文描述概念改进的各种方案中所涉及的物理问题，并扼要评述了现在研究的主要实验结果。     

托卡马克的实验结果

本文从ＭＨＤ不性、等离子体中快粒子、电流分布、面对等离子体的材料、等离子体加热和电流驱动、热和粒子排出及等离子体约束等方面，扼要介绍了托卡马克的主要实验结果。     

Bootstrap current fraction scaling for a tokamak reactor design study

We have derived new bootstrap current fraction scalings for systems codes by solving the Hirshman–Sigmar model, which is valid for arbitrary aspect ratios and collision conditions. The bootstrap current density calculation module in the ACCOME code was used with the matrix inversion method without the large aspect ratio assumption. Nine self-consistent MHD equilibria, which cover conventional, advanced and spherical tokamaks with normal or reversed shear, were constructed using numerical calculations in order to compare the bootstrap current fraction values with those of the new model and all six existing models. The Wilson formula successfully predicted the bootstrap current fraction, but it requires current density profile index for the calculation. The new scaling formulas and IPDG accurately estimated the bootstrap current fraction for the normal and weakly reversed shear tokamaks, regardless of the aspect ratio. However, none of the existing models except the Wilson formula can accurately estimate the bootstrap current fraction for the reversed shear tokamaks, which is promising for the advanced tokamak operation mode.     

Study of electromagnetic interference on quench detecting system of HTS current leads for EAST

High temperature superconducting (HTS) material B-2223/Ag-Au has been used for EAST poloidal field (PF) coil current leads for reducing construction and operation cost of cryogenic system. The quench propagation velocity of HTS superconducting material is several orders of magnitude lower than that of normal low temperature current leads. It is difficult to detect weak signal of quench which is easily influenced by strong electromagnetic interference (EMI). In this paper, the sources of EMI from quench detecting system of high temperature current leads have been introduced. And we have chosen reasonable methods for good transformation and protection on the basis of electromagnetic compatibility simulation diagnosis experiments. Recent experimental results showed that the restraint of EMI has been achieved and has met the requirements of experiment.     

HT-7超导托卡马克装置上中子通量分布的实验研究

本文介绍了HT-7超导托卡马克装置上中子通量分布的测量实验.在实验中,使用了两种有较强抗伽马能力的中子探测系统:BF3和3He正比计数管及其相应的电子学与数据采集.在2005年春季实验中,在相同实验条件下,细致测量并比较研究了真空室外不同水平位置、垂直位置的中子通量.实验研究了真空室窗口和变压器铁芯的存在对测量结果的影响,验证了测量结果与三维数值计算的一致性.本项工作为更深入的物理研究奠定了基础.     

Experimental Results of IBW Heating on the HT-7 Tokmak

Ion Bernstein waves (IBWs) have been proposed to be useful for heating and improving transport in tokamak plasmas. An Ion Bernstein wave heating experiment using different frequency (27 MHz and 30 MHz) was carried out on HT-7 superconducting tokamak in recent experiments. At a frequency of 30 MHz, ne peaked and Hα dropped have been pervasively observed,τp was improved by a factor of 2～4, and τe increased by a factor of 1～1.5. An obvious confinement of particle was observed during the IBW pulse. At 27MHz, both global and localized electron heating were observed depending on the location of the ion resonant layer by changing Bt.Central electron heating effect was obtained in the global heating mode and electron temperature strongly increased near the 2 ΩD resonant layer for localized heating mode.     

上海光源直线加速器的弱流强运行

上海光源(SSRF)直线加速器正常运行时,重复频率2 Hz,单束团脉宽1 ns,电荷量1 nC。近年来,国际同步辐射领域发展起来的恒流注入模式要求直线加速器以弱流强运行,在相同的重复频率和脉宽下,单脉冲电荷量越小越好,此方法重复性较好。本文在理论计算基础上,结合实验,给出了弱流强稳定运行的实现方法,确定了在Top-up模式下,直线加速器的脉冲电荷量为0.1 nC。     

Experimental study of current loss of a single-hole post-hole convolute on the QG I generator

The post-hole convolute(PHC), which is used to transport and combine the pulse power flux, is a key component in huge pulsed power generators. Current loss at the PHC is a challenging problem for researchers. To explore a method of reducing the current loss, a single-hole PHC was designed for experiments on the current loss on the Qiang Guang I generator. The experimental results showed that the current loss at the single-hole PHC is related to the distance l between the vicinity of the cathode hole and the surface of the downstream side of the post.Meanwhile, a single-hole PHC with a blob cathode hole transmitted current more effectively than the PHC with a circle cathode hole. The relative current loss at the single-hole PHC with the cathode coated with gold foil was about 30%–50% of that with the cathode coated with nickel and titanium foil. The gap closing speed was also obtained from the current waveforms in the experiments. The speed was 5.74–14.52 cm μs~(-1) which was different from the classical plasma expansion velocity of 3 cm μs~(-1) .     

低杂波电流驱动下HT-7超导托卡马克等离子体硬X射线辐射研究

用７个ＮａＩ（Ｔｌ）闪烁探测器组成的阵列观测能量范围在２０－５００ｋｅＶ,来自ＨＴ－７托卡马克等离子体的硬Ｘ射线轫致辐射。实验结果显示,硬Ｘ射线的径向辐射强度分布与低杂波的功率谱和等离子体的密度及磁志强度等放电参数密切相关。通过测量不同放电参数下硬Ｘ射线的径向强度分布,研究低杂波在等离子体中传播和吸收机制。     

Design criteria and current status of LHCD system on SST1 machine

The lower hybrid current drive (LHCD) system for superconducting steady state tokamak-1 (SST-1) machine is in advanced stage of integration and commissioning. The system is designed to launch 1 MW of RF power at a frequency of 3.7 GHz to sustain 220 kA of plasma current non-inductively for 1000 s. The system employs a conventional grill antenna (having 2 × 32 waveguides), vacuum and air transmission lines and high power source system. A new design for vacuum transmission line, which enables better vacuum and RF compatibility has been successfully executed and tested. The transition from the narrow waveguide to WR284 waveguide system is achieved through a simple design, having stacks of copper plates with the waveguides milled in them, referred as transforming module and is successfully tested for mechanical, vacuum and RF performance. Many of the critical components have been successfully fabricated and tested as per the designs. The components and sub-systems are made ready and the integration is in progress. All the components are actively cooled and are compatible with 1000 s operation.The performance tests and current status of various sub assemblies and partially integrated LHCD system is discussed in detail in this paper.     

SUNIST球形托卡马克的研究进展

球形托卡马克为聚变能的商业应用提供了一条可能的途径。中国联合球形托卡马克SUNIST以真空室的环向和极向都有绝缘隔缝为结构特征。该装置的主要任务是研究低环径比等离子体的基本特性和等离子体的非感应加热与电流驱动。包括同轴磁螺旋性注入电流启动、电极放电辅助电子回旋波电流启动、电子伯恩斯坦波以及离子高次谐波快波加热与电流驱动。装置已经顺利组装完毕,并安装了磁测量、静电探针和软X射线等基本的诊断系统。目前正处于系统联调阶段。     

AC operation of large titanium sublimation pumps in a magnetic field: Results of the test stand for the W7-X neutral beam injectors

A neutral beam injection (NBI) system is being built for the Stellarator experiment Wendelstein 7-X (W7-X) currently under construction at IPP Greifswald. The NBI system consists of two injectors which are essentially a replica of the system present in the Tokamak experiment ASDEX-Upgrade at IPP Garching. A vacuum system with high pumping speed and large capacity is required to ensure proper vacuum conditions in the neutral beam line. For this purpose, large titanium sublimation pumps (TSP) are installed inside the NBI boxes, consisting of 4 m long hanging wires containing Ti and the surrounding condensation walls. The wires are DC ohmically heated up with 142 A to Ti sublimation temperature. A TSP system has been operated since many years in the AUG-NBI system, sublimating Ti in the pauses between the plasma discharges, when no magnetic field is present. However, at W7-X the superconducting coils generate a magnetic field permanently during experimental campaigns, whose stray B field with a maximum of 30 mT, affects the TSPs. Operated with DC, the wires would be deflected against the surrounding panels due to the Lorentz force. A simple possible solution is heating with AC, which reduces the wire deflection amplitude, inducing a risky wire oscillation. The feasibility of the AC operation in an equivalently strong B field such as the stray B field around W7-X has been demonstrated in a test stand for different AC waveforms and frequencies. Several test campaigns have shown no qualitative difference in the pumping properties between AC and DC operation of the TSP and no critical dynamic behaviour of the wires.