KSTAR equilibrium operating space and projected stabilization at high normalized beta
KSTAR equilibrium operating space and projected stabilization at high normalized beta
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DOI：
10.1088/0029-5515/51/5/053001
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发表时间：
2011-05
期刊：
影响因子：
3.3
通讯作者：
Y. Park;S. Sabbagh;J. Berkery;J. Bialek;Y. Jeon;S. Hahn;N. Eidietis;T. Evans;S. Yoon
中科院分区：
文献类型：
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作者：
Y. Park;S. Sabbagh;J. Berkery;J. Bialek;Y. Jeon;S. Hahn;N. Eidietis;T. Evans;S. Yoon
随着韩国超导托卡马克高级研究（KSTAR）平衡工作空间的扩展评估，使用EFIT代码重建了最近等离子体放电的实验平衡。在2009年创建的近圆形等离子体中，平衡态达到了54 kJ的存储能量，最大等离子体电流为0.34 MA。2010年，具有近双零结构的高形状等离子体实现了具有明显边缘局域模式（ELM）活性的h模式，瞬时存储能量高达257 kJ，伸长率为1.96，归一化β为1.3。等离子体电流达到0.7 MA。利用设计的控制硬件，还考虑了在理想无壁β极限以上运行时，对MHD全局不稳定性进行主动和被动稳定化。在等离子体电流为2 MA，内感为0.7，归一化β为4.0，密度、温度和旋转分布简单的KSTAR理论平衡上，利用MISK程序计算了理想MHD n = 1稳定性判据的动力学修正。这种平衡的陡峭边缘压力梯度导致需要显著的等离子体环向旋转，以允许热粒子动力学共振来稳定电阻壁模式（RWM）。分析了各种材料和被动稳定板的电气连接对RWM增长率的影响，与不锈钢板相比，铜板使RWM被动增长率降低了15倍，标准化贝塔系数为4.4。利用VALEN代码进行的有源RWM控制计算表明，在理想控制系统假设下，通过控制功率低至0.83 kW的中层容器内控制线圈（ivcc）产生的控制场，可以将n = 1模式稳定在理想壁面极限附近的归一化β。通过评估共振磁扰动产生的真空岛重叠来检查IVCC的ELM缓解潜力，并使用TRIP3D代码进行分析。利用n = 2场占主导地位的所有ivcc和偶奇偶位态上/下线圈的组合，在理论性高β平衡下生成了归一化极向通量0.83处接近统一的Chirikov参数，这是DIII-D中ELM缓解的经验确定条件。Chirikov剖面优化解决了线圈奇偶校验和安全系数剖面。
Along with an expanded evaluation of the equilibrium operating space of the Korea Superconducting Tokamak Advanced Research, KSTAR, experimental equilibria of the most recent plasma discharges were reconstructed using the EFIT code. In near-circular plasmas created in 2009, equilibria reached a stored energy of 54 kJ with a maximum plasma current of 0.34 MA. Highly shaped plasmas with near double-null configuration in 2010 achieved H-mode with clear edge localized mode (ELM) activity, and transiently reached a stored energy of up to 257 kJ, elongation of 1.96 and normalized beta of 1.3. The plasma current reached 0.7 MA. Projecting active and passive stabilization of global MHD instabilities for operation above the ideal no-wall beta limit using the designed control hardware was also considered. Kinetic modification of the ideal MHD n = 1 stability criterion was computed by the MISK code on KSTAR theoretical equilibria with a plasma current of 2 MA, internal inductance of 0.7 and normalized beta of 4.0 with simple density, temperature and rotation profiles. The steep edge pressure gradient of this equilibrium resulted in the need for significant plasma toroidal rotation to allow thermal particle kinetic resonances to stabilize the resistive wall mode (RWM). The impact of various materials and electrical connections of the passive stabilizing plates on RWM growth rates was analysed, and copper plates reduced the RWM passive growth rate by a factor of 15 compared with stainless steel plates at a normalized beta of 4.4. Computations of active RWM control using the VALEN code showed that the n = 1 mode can be stabilized at normalized beta near the ideal wall limit via control fields produced by the midplane in-vessel control coils (IVCCs) with as low as 0.83 kW control power using ideal control system assumptions. The ELM mitigation potential of the IVCC, examined by evaluating the vacuum island overlap created by resonant magnetic perturbations, was analysed using the TRIP3D code. Using a combination of all IVCCs with dominant n = 2 field and upper/lower coils in an even parity configuration, a Chirikov parameter near unity at normalized poloidal flux 0.83, an empirically determined condition for ELM mitigation in DIII-D, was generated in theoretical high-beta equilibria. Chirikov profile optimization was addressed in terms of coil parity and safety factor profile.