强磁场下ITER垂直稳定性线圈的电磁性能研究

垂直稳定性线圈是ITER托卡马克装置中用以维持等离子体垂直稳定性的核心部件,然而该线圈处于强磁环境下,一旦线圈励磁运行以后,线圈电流与外部背景场交互作用激发的电磁载荷将会对线圈产生强烈的电磁冲击.为了分析稳态和瞬态电磁载荷对线圈结构的影响,首先采用电流丝等效模型并基于椭圆积分计算了背景场线圈和等离子体电流的磁场,以及极端运行状态下背景场所诱发的电磁力.在电磁计算的基础上,创建循环对称磁-结构耦合分析模型并采用间接耦合法,将电磁力密度以载荷边界条件插值到结构分析模型,计算评估线圈在稳态电磁载荷下的力学性能.此外,针对脉冲电流引起的电磁疲劳,采用ASME主应力方向恒定的疲劳设计规范,结合Goodman修正法并以无限次循环条件下材料应力强度为评定标准,对线圈各组件的应力进行了评定,结果表明线圈各组件均有足够的安全裕度.该分析方法可为托卡马克其它磁体线圈的电磁性能评估提供参考.

The Study on Electromagnetic Performance of ITER Vertical Stability Coilunder Strong Magnetic Field

Vertical stability coil is the key component of ITER device to sustain the vertical stability of plasma. However, the coil is under the strong magnetic field. Once the coil is charged, the severe electromagnetic shock willbe caused due to the interaction of coil current and background field. In order to analysis the effect on coil structure caused by steady and instantaneous electromagnetic loads. Firstly, the filament equivalent model is adopted and based on elliptical integral the magnetic field caused by background field and plasma current is calculate.Meanwhile the electromagnetic force induced by the strong magnetic field are also calculated.On the basis of electromagnetic calculation, the cyclic-symmetric electromagnetic-structural coupling analysis model is created and the indirect coupling method is selected. In order to study the mechanical performance of vertical stability coilin the steady electromagnetic load, the electromagnetic force density is interpolated into the structural analysis model as the load boundary condition. Meanwhile, aiming at the electromagnetic fatigue induced by pulse current, the ASME fatigue design specification with constant principal stress isused. Combining Goodman formula, the value of material stress intensity under infinite cycling is chosen as the evaluation criteria.Finally, the stress of coil component is assessed. The study results indicate all the components have enough safety margin.The method presented in the paper can provide a reference for other Tokamak In-vessel coils.