HL-2A极向场线圈系统的优化设计

通过对原ＡＳＤＥＸ极向场线圈系统进行改造,优化设计出ＨＬ－２Ａ极向场线圈系统,模拟计算了磁场位形演化并估算了伏秒消耗。改造后的极向场线圈系统能够形成８００ｋＡ的等离子体电流,并能产生拉长截面的等离子体偏滤器的位形。分析了改造后的极向场线圈系统的电磁特征,计算了单零,双零及Ｄ形限制器三种等离子体平衡位形。     

CFETR PF 导体设计及稳定性分析

中国聚变工程试验堆(CFETR) 是一种新型的超导托卡马克装置, 极向场线圈(PF) 在控制等离子体位行中起着关键作用. CFETR PF 线圈导体由 Nb3Sn CICC 和 NbTi CICC 导体组成. 为了确保 PF 线圈的稳定运行, 本文采用1-D Gandalf 对不同机械扰动和电磁扰动下 PF 导体的稳定性裕度, 最小失超能量及温度裕度的进行了分析. 分析结果表明 CFETR PF 导体目前的设计能够充分满足安全裕度的要求     

Tokamak plasma equilibrium analysis based on the relaxation method with a specified magnetic axis

In this contribution, we have presented two techniques for the determination of plasma equilibrium position in IR-T1 tokamak: relaxation and optical methods. An analysis method of tokamak plasma equilibrium by a relaxation method with a specified magnetic axis is presented. The degrees of freedom due to designated positions of the magnetic axis are possible by using poloidal field coil currents. Stable steady-state tokamak plasma equilibria are calculated along with the magnetohydrodynamic potential energy. The plasma generates a plasma current which partially or fully cancels the magnetic field from the poloidal field coils. For low-temperature plasmas, the plasma current distribution is centrally peaked; for high-temperature plasmas, the plasma current has a hole. A centrally peaked current distribution in a low-temperature plasma is evolved into a current distribution with a hole by increasing the plasma pressure by Ohmic heating, radio frequency heating, or by neutral beam injection heating. In the second technique, an image-processing technique was used for the output signal of the charge coupled device camera and plasma emission intensity profile and then the plasma position was obtained. Results are compared and discussed.     

HL-2M 初始放电位形及波形设计

利用 EFIT 设计了可用于 HL-2M 初始放电的圆截面限制器位形以及偏滤器位形;设计了满足放电击 穿条件要求(零场区域平均杂散磁场应不超过 20G)的零场位形。综合分析放电过程伏秒数消耗及真空室涡流的影 响,使用 PF8 线圈电流补偿真空室涡流产生的杂散磁场,设计了等离子体电流 200kA 的限制器位形及偏滤器位形 的自洽的放电波形。将该放电波形作为放电调试的参考波形,成功实现了限制器位形的初始放电实验。      

在单一和连续等离子体放电条件下KSTAR PF线圈的运行特性分析

我们使用分析程序SAITOKSCPF研究了KSTAR PF 超导线圈的运行特性.为了控制KSTAR超导托卡马克的运行等离子的外形以便实现受控热核聚变反应,在超导PF线圈内通过高变化率的运行电流.由于电磁感应,在超导线圈、支持结构和低温容器内产生感应电流和损耗.超临界氦流过CICC导体内部保持超导体运行在4.2K的温度.分析表明最大的温度在PF1线圈内部.在这篇论文中,我们对于单一和连续条件下等离子体放电对超导体运行的影响进行了研究.     

Inhomogeneity of currents in a wire array during its explodingphase

The current in a wire array during its exploding phase has been studied. The wire array consisting of many thin wires is used as a plasma source in a z-pinch X-ray radiation system. The current distribution in the exploding wire array plays an important role in producing an initial symmetrical plasma. In the present experiment, four tungsten wires of 0.1 mm in diameter were exploded in a vacuum. The experiment was carried out with an inductive voltage adder pulsed power generator providing a current of 160 kA at quarter period of 1.8 μs The currents through and the voltage across the wires were measured simultaneously. It was found that the currents in the wires were inhomogeneous, especially after the wires became plasma. Once the currents became inhomogeneous, the inhomogeneity remained throughout the discharge. It was also studied how the dimensions of the wires affected the homogeneity of the currents. Wires of different lengths or different cross sectional areas resulted in strong inhomogeneities of the currents. The wires with shorter length or smaller cross-sectional area became plasmas earlier than other wires. Thus, the resistances of the wires were not equal. These differences in the resistance caused the inhomogeneity of the currents     

平行轨道加速器等离子体动力学特性研究

等离子体电磁加速器可产生高速度、高密度等离子体射流而广泛应用于核物理、天体物理等领域.本文通过光电二极管、磁探头研究了不同放电电流和初始气压条件下等离子体在平行轨道加速器内的轴向运动特性.通过电流截断的方法,采用冲击摆测量了首次等离子体射流的动量.平行轨道加速器驱动电源由14级脉冲形成网络组成,每级电容为1.5μF,每级电感约为300 nH,得到振荡衰减型方波的电流波形.实验发现,电流过零时,轨道起始处一般会发生二次击穿,并形成二次轴向运动的等离子体.放电电流为10—55 kA、初始气压为200—1000 Pa时,等离子体的轴向速度为8—25 km/s.实验获得的等离子体的运动速度为雪犁模型理论结果的60%—80%,这主要是理论模型忽略了电极表面对电弧的黏滞阻力以及电极烧蚀引起的质量增加.等离子体动量与电流的平方随时间的积分成正比.放电电流为21-51.6 kA时,首次等离子体射流的动量为1.49—9.88 g·m/s.等离子体运动过程中除了受到洛伦兹力外,还会受到电极表面的黏滞阻力,造成等离子体动量约为理论结果的75%.     

缩短两级爆磁压缩发生器输出脉冲宽度的一种途径

 缩短两级爆磁压缩发生器输出脉冲宽度的一种有效办法是增大第二级螺旋线圈的锥角，但增大锥角会降低发生器电感压缩比，合理的锥角设计是此类发生器的关键。介绍了三种能带大电感负载、结构紧凑的两级爆磁压缩发生器，第一级结构参数相同，第二级螺旋线圈锥角分别为6°，8°，10°。在电感负载上进行的实验结果表明：其输出电流分别达到140，90和50 kA，电流脉冲宽度分别为12.5，8.5和6.3 μs，对应的名义输出功率分别为7，7和3 GW。     

环形等离子体平衡时维持场电流的计算

本文介绍一个计算轴对称任意截面环形等离子体平衡问题的方法。先选定等离子体边界和环电流分布,用有限元方法解平衡方程的边值问题。借助于虚壳原理,得到用平衡方程解表示的能够产生平衡时所需要的维持场的虚壳电流。计算虚壳电流在等离子体区的维持场,以它为根据,采用积分方程开拓,求等离子体区外某位形上的维持场电流分布。解决这个问题的主要困难是当磁场向外开拓时遇到了不适定问题。我们用奇异值分解方法解不适定的Fredholm第一类积分方程。这个方法能容易地找到稳定解,对解决这个平衡问题是简单有效的。我们以七种等离子体截面形状,三种电流分布为具体模型,在三种维持场电流分布位形上给出了维持场电流分布。还给出了维持场形态,维持场总电流与等离子体总电流的比较,并简单讨论了维持场对等离子体整体稳定性的影响。 关键词：     

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A hybrid structure was adopted for the PF coil of the building HL-2M device. In the process of discharge, there is a strong coupling between the coils, each coil will be subjected to a large electromagnetic force. In this paper, PF coil electromagnetic force is computed by the analytic method under the discharge conditions of the largest I_p =3MA plasma current and various configurations. These calculation results are of reference value for the design of PF coil and its support structure.     

HL-2M 装置运行控制技术初步研究

重点介绍了 HL-2M 装置的运行技术和初步的等离子体控制实验结果,包括等离子体放电方案设计、 线圈电流控制、击穿阶段零场匹配和等离子体电流以及位移的控制。为了降低放电运行风险,HL-2M 装置初始放 电采用了简化的放电方案,通过整定 PID 参数实现了线圈电流控制,在击穿阶段获得了 10V 以上的环电压和较大 范围的零场区域,成功实现等离子体击穿。最后,投入了等离子体电流和水平位移反馈控制算法,成功将等离子 体放电脉宽提升至 200ms 以上,且维持 I_p≥100kA 的时间超过了 100ms,上述结果表明 HL-2M 装置运行控制技术 得到了初步的检验。      

中心螺管模型线圈交流损耗计算及测试

中心螺管模型线圈选用 Nb Ti/ Cu复合超导材料 ,超导股线直径 0 .85 m m,Cu截面积与 Nb Ti截面积比为 1.38;经过 4级绞缆和成型 ,导体尺寸为 17.4 mm× 17.4 m m,中心冷却孔直径 4 .1m m。线圈用超临界氦冷却 ,流体进口温度为 3.8- 4 .2 K,压力 6 bar,每个流道流量 2 .2 g/ s。用量热法对中心螺管模型线圈进行了交流损耗测试并与计算值相比较 ,3次交流损耗电流分别是 :30 0 A/ s速度励磁和放电 ,最大电流 5 k A ,交流损耗测量值为每脉冲 78.3J;30 0 A / s速度励磁和放电 ,最大电流 7k A ,交流损耗测量值为每脉冲 14 0 .7J;4 0 0 A/ s速度励磁和放电 ,最大电流 7k A,交流损耗测量值为每脉冲14 5 .4 J;计算值分别为每脉冲 98J,1385 J,14 2 J;两者较好相符。     

HL-2M极向场线圈电磁力的计算分析

在建的HL-2M装置的PF线圈采用了混合式结构。在放电过程中,线圈之间有很强的电磁耦合,每一个线圈都会受到很大电磁力的作用。采用解析法,在最大I_p=3MA等离子体电流和各种位形的放电条件下,计算分析了PF线圈受到的电磁力。这些计算结果对PF线圈及其支撑结构的设计都是具有参考价值的。     

磁光式无源传感器测量脉冲电流

利用国产磁光玻璃材料、发光二极管LED以及光电二极管PIN,制成了一套磁光式无源传感器,用来测量脉冲电流。这套测量设备的上升时间为300ns,可用来记录雷放电电流、等离子体实验中的脉冲电流及高功率脉冲装置中的电流。     

HL-2M 装置极向场线圈的结构设计与制造

介绍了 HL-2M 装置极向场(PF)线圈的结构设计和制造。16 饼 PF 线圈布置在环向场(TF)线圈空腔之 内、真空室外,沿中平面对称分布。PF 线圈采用中空矩形铜导体绕制,其中 PF1~PF4 线圈为双层螺旋绕制结构, 最大运行电流 14.5kA;PF5~PF8 线圈为多层盘式绕制结构,最大运行电流 38~42kA。      

Interaction between Vacuum Arcs and Transverse Magnetic Fields with Application to Current Limitation

The interaction between diffuse vacuum arcs and magnetic fields applied transverse to the electrode axis has been investigated both theoretically and experimentally. For arc currents < 6 kA, Hall electric fields, generated by the interaction, bow the plasma out of contact with the anode and raise the arc voltage. In the presence of a parallel capacitor, the arc current falls to zero and the arc is extinguished. For arc currents of 6 to 15 kA, arc extinction can be achieved with an oscillatory magnetic field; during such extinctions the arc voltage remains in phase with the magnitude of the field. Arc extinction via magnetic field/vacuum arc interaction could have applications to ac-current limiters and dc breakers. The fault current limiter application is discussed in this paper.     

Eddy current effects on plasma equilibrium in a single-turn tokamak

In a fusion experiment based on the single-turn tokamak concept, the plasma is surrounded by a massive conducting structure composed of several layers of material with different resistivities. This conducting shell is located near the plasma edge and is magnetically coupled to the plasma column. The plasma magnetohydrodynamic (MHD) equilibrium is studied by neglecting the effect of structural induced currents. Eddy current effects are then analyzed. Poloidal uniformization of the poloidal field magnet current distribution required for plasma equilibrium is demonstrated. The possibility of continuous-limiter discharges in a single-turn tokamak configuration is pointed out. The significance of these results for the operation of a high-current tokamak experiment is discussed     

ITER 68 kA高温超导特大电流引线研发

国际受控热核聚变试验堆由18个D形环向场线圈、6个中心螺管线圈、6个圆形极向场线圈和18个校正场线圈组成巨大的超导磁体系统.为大幅度减小磁体系统的低温制冷设备投资和日后的运行费,采用容量分别为68、52、45和10 kA总共30对高温超导电流引线馈电.不仅电流容量特大、安全性要求特高,而且还需承受低真空下巴申放电条件的30 kV直流高电压.本文介绍68 kA电流引线的相关设计和研发.     

Optimization and performance of a high-speed plasma position digital control system

This paper addresses optimization of a high-speed digital feedback controller for a plasma position in Damavand tokamak. Damavand tokamak discharges have plasma currents up to 40 kA with discharge duration greater than 15 ms and toroidal magnetic fields up to 1.2 T. The plasma position is measured using saddle-loops and Rogowski coil and is controlled by electromagnetic forces generated by passing currents through control coils placed around the plasma. A desired control objective is maintaining the plasma in the center of vacuum vessel and to stabilize the plasma in the presence of disturbances in a time domain of the order of few milliseconds. In order to achieve maximum performance it is essential to optimize the control system. In this paper plasma position measurement and the details of implementing high-speed PID controllers based on a TMS320c25 digital signal processor along with the system optimization are presented.