Plasma Confinement Improvement with a Local Island Divertor

使用本地岛偏滤器改善等离子体限制

• 批准号: 16206092
• 负责人: KOMORI Akio
• 金额: $ 31.53万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16206092/
• 关键词: divertor; magnetic island; edge plasma control; edge plasma; ergodic layer; heliotron configuration; LID

During the research for four years, we discovered a high density operational regime by the central fuelling with the pellet injection and the strong pumping with the Local Island Divertor (LID). In this discharge, the superdense core region with the density more than 5×10^<20> m_<-3> and the temperature of〜0.8 keV is maintained by an Internal Diffusion Barrier (IDB) formed in the confinement region. These high parameters in the core plasma consequently provided the highest plasma performance (fusion triple product, n_0T_0τe=2.8×10^<19>m_<-3>keVs) obtained so far in the Large Helical Device (LHD). The LID is a kind of island divertor which utilizes an m/n=1/1 magnetic island artificially induced by the perturbation coils. The LID has the efficient pumping capability with its closed configuration and strong pumping system despite its compactness, which therefore brings about low particle recycling, i.e. low edge density.In the recent experiments, however, it was found that such a high de … More nsity discharge with peaked electron density profile could be obtained not only in the LID configuration but in the Helical Divertor (HD) configuration, if only the reduced recycling could be achieved by the exhaustive wall conditioning. In the HD configuration with large flexibility of the magnetic field configuration, experiments were performed shifting the magnetic axis from standard position to outward shifted one. After the optimization of operational conditions, it was often observed that the central density collapse (CDC) took place with the increase of the central plasma pressure. In the CDC, the abrupt density decay at the center and the increase at the edge region were observed, suggesting the particle flush from the core region. In order to avoid the CDC, an attempt to suppress the Shafranov shift (outward shift of the plasma column) was made by changing the plasma shape. An effective result was obtained in the experiment with the expansion of the plasma parameters. The impurity behavior during the high density discharge was also investigated. In spite of the peaked density profile with IDB, no serious impurity accumulation was observed, although a certain quantity of carbon was sputtered on the surface of the divertor plates. This experimental result was also demonstrated by the numerical calculation with the EMC3-EIRENE code which suggests the strong parallel flow in the ergodic region to play an important role in impurity screening with its strong frictional force. Less

在四年的研究中，我们发现了一个高密度的操作制度，即用颗粒注入中央加油和用局部岛屿分流器（LID）强泵。在此放电过程中，约束区内形成的内部扩散势垒（IDB）维持了密度大于5×10^<20> m_<-3>、温度为~ 0.8 keV的超密核心区。核心等离子体中的这些高参数提供了迄今为止在大型螺旋装置（LHD）中获得的最高等离子体性能（聚变三重积，n_0T_0τe=2.8×10^<19>m_<-3> kfs）。LID是一种利用微扰线圈人工诱导的m/n=1/1磁岛的海岛导流器。尽管LID结构紧凑，但其封闭的结构和强大的泵送系统具有高效的泵送能力，因此带来了低颗粒回收，即低边缘密度。然而，在最近的实验中发现，不仅在LID构型中，而且在螺旋分流器（HD）构型中，只要通过尽举壁面调节实现减少循环，都可以获得更大的峰值电子密度分布的密度放电。在磁场构型灵活性较大的HD构型下，进行了将磁轴由标准位置向外移位的实验。优化运行条件后，随着中心等离子体压力的增大，中心密度坍缩（CDC）现象时有发生。在中心区域密度急剧衰减，边缘区域密度增大，表明粒子从核心区冲出。为了避免CDC，试图通过改变等离子体形状来抑制沙弗拉诺夫位移（等离子体柱向外移动）。通过对等离子体参数的扩展，得到了有效的实验结果。并对高密度放电过程中的杂质行为进行了研究。尽管有峰值密度分布，但没有观察到严重的杂质堆积，尽管在导流板表面溅射了一定量的碳。EMC3-EIRENE代码的数值计算也证实了这一实验结果，表明遍历区的强平行流以其强大的摩擦力在杂质筛选中起着重要作用。少

项目成果

Flux Surface Mapping in LHD

LHD 中的通量表面映射

• 发表时间: 2007
• 作者: T.Morisaki;et. al.
• 通讯作者: et. al.

Three-dimensional proton trajectory analyses and simulation of neutral particle transport in an ICRF heated long pulse discharge on the large helical device

大型螺旋装置上 ICRF 加热长脉冲放电中的三维质子轨迹分析和中性粒子输运模拟

• 发表时间: 2005
• 期刊: Journal of Nuclear Materials 337-339
• 作者: A. Ushida;T. Sugiyama;Y. Enokida;I. Yamamoto;Kuniyuki Omagari et al.;M.Shoji
• 通讯作者: M.Shoji

Formation and healing of n=1 magnetic island in LHD equilibrium

LHD 平衡中 n=1 磁岛的形成和愈合

• 发表时间: 2005
• 期刊: Nuclear Fusion 45
• 作者: H.Kurishita;S.Matsuo;H.Arakawa;S.Kobayashi;K.Nakai;T.Takida;K.Takebe;M.Kawai;R.Kanno
• 通讯作者: R.Kanno

IDB-SDC放電における周辺プラズマの役割

外周等离子体在 IDB-SDC 放电中的作用

• 发表时间: 2007
• 作者: 長山好夫;成嶋吉朗(3番目);大藪修義(4番目);森崎友宏(11番目);他14名;長山好夫;森崎友宏;森崎友宏;森崎友宏;森崎 友宏;鈴木康浩;小林政弘;増崎貴;森崎友宏;森崎友宏;森崎友宏;小林政弘;増崎貴;小林政弘;小林 政弘;森崎 友宏
• 通讯作者: 森崎 友宏

Edge plasma control by helical and local island divertors in LHD

LHD 中通过螺旋和局部岛偏滤器进行边缘等离子体控制

• 发表时间: 2007
• 作者: J. Miyazawa;et al.;森崎友宏;森崎 友宏;H. Yamada;森崎友宏;増崎貴;宮澤順一;坂本隆一;小林政弘;宮澤 順一;森崎 友宏;坂本 隆一;増崎 貴;S. Masuzaki;S. Masuzaki;S. Masuzaki;M. Kobayashi;J. Miyazawa;R. Sakamoto;K. Tanaka;J. Miyazawa;R. Sakamoto;田中 謙治;宮澤 順一;坂本 隆一;R. Sakamoto;K. Tanaka;R. Sakamoto;田中 謙治;坂本 隆一;森崎友宏;森崎 友宏;K. Tanaka;田中 謙治;H. Yamada;山田 弘司;J. Miyazawa;宮澤 順一;増崎 貴;S. Masuzaki;T. Morisaki
• 通讯作者: T. Morisaki