基于电磁能量转移的等离子体破裂防护方法研究

Tokamak is a complex electromagnetic device which confines the plasma in vacuum vessel to fusion using the magnetic field produced by coils, the plasma current is maintained for the device operation. The plasma disruption is happened with the plasma current declined fast and disappeared in few milliseconds because of plasma instabilities. Disruption often causes damage to the fusion devices by means of heat load and runaway electrons. The disruption mitigation has already become one of the hottest research point for the serious damage to the device and not be avoided.However these existing methods do not reduce the energy consumption left in the vacuum vessel, the disruption mitigating effects on the ITER Tokamak with large scale is still a subject to proof. A new disruption mitigation method to migitage the disruption damage by transferring the plasma electromagnetic energy out of the tokamak device through electromagnetic coupling of multiwinding transformer, will be introduced in this project, and the energy consumption left in the vacuum vessel would be reduced. Specifically, we plan to investigate the transient state process of plasma current and the total magnetic energy and its evolution process, build the multi-loop electromagnetic coupling model, explore disruption mitigation method via energy transference，and verify the feasibility and the effects of the energy transfer coil on plasma disruption mitigation through experiment on the tokamak device. The new plasma disruption mitigate method will be good references for further tokamak researches.

托卡马克是利用多个线圈产生磁场对环形真空室内的等离子体进行约束的复杂电磁装置，在其运行过程中等离子体电流有时会在极短时间内迅速下降并消失，发生等离子体破裂。等离子体破裂过程中巨大的电磁能量和内能会以热沉积、逃逸电子等方式作用在装置上，可能会对装置造成极大的破坏，因而破裂防护是聚变装置安全运行必须解决的关键问题。现有的破裂防护方法没有减少沉积在真空室内的能量总量，能否有效保障ITER及未来聚变堆的安全尚有待检验。本项目拟从新的角度，基于电磁耦合原理，利用与等离子体耦合的线圈将破裂时部分电磁能量转移到真空室外部，减小沉积在真空室内部的能量总量，达到破裂防护的目的。本项目研究破裂时等离子体电流的瞬态过程和磁能演化，建立多回路变压器电磁耦合模型研究能量转移过程，在J-TEXT装置上验证基于电磁能量转移的破裂防护方法的可行性及效果，研究成果有望为未来托卡马克破裂防护提供新思路。

托卡马克装置等离子体破裂会带来热沉积、电磁力和逃逸电流等危害，严重威胁装置安全，等离子体破裂防护是ITER等未来大型托卡马克装置必须解决的关键问题。针对托卡马克装置等离子体破裂防护问题，本项目从降低耗散在真空室内磁能的角度出发，提出了基于能量转移的破裂缓解方法，并结合J-TEXT托卡马克装置开展了相关理论与实验研究。建立了J-TEXT托卡马克装置磁能演化分析模型，研究了等离子体破裂过程中的磁能耗散规律，并开展了相关实验测试，从理论和实验上证明了破裂过程中绝大多数（80%-100%）磁能将会耗散在真空室内的结论。开展了基于外加线圈极向磁能转移研究，在J-TEXT装置上搭建了磁能转移实验系统并开展了相关实验研究，获得了24%的磁能转移效率，并观察到极向磁能转移降低环电压、缓解逃逸电流、控制逃逸电流水平位移的效果。为了进一步提升极向磁能转移的破裂缓解效果，提出了基于电容放电的有源极向磁能转移方法并开展了实验验证，能量转移效率提升至43.3%，降低环电压和缓解逃逸电流的效果更加明显。最后，以EAST装置为分析对象，开展了极向磁能转移方法在空芯托卡马克装置上的应用效果研究，获得了空芯装置极向磁能转移系统设计的指导性原则。本项目提出了一种新的破裂缓解方法，其研究成果对未来托卡马克装置破裂防护系统的设计具有重要的参考价值。