Overview of JT-60U progress towards steady-state advanced tokamak
Overview of JT-60U progress towards steady-state advanced tokamak
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DOI：
10.1088/0029-5515/45/10/s05
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发表时间：
2005-10
期刊：
影响因子：
3.3
通讯作者：
S. Ide
中科院分区：
文献类型：
--
作者：
S. Ide
本文介绍了JT-60 U稳态先进托卡马克（AT）研究的最新实验结果，重点是与等离子体特征时间尺度相比较的更长时间尺度。为了实现这一目标，对操作、加热和诊断系统的控制进行了修改。结果得到了1060 s的电流平顶和1030 s的H模。长脉冲改装为JT-60 U开辟了一个新的领域。在高βp H模式等离子体中，2.3的高归一化β（βN）保持22.3 s，2.5保持16.5 s。一个标准的ELMy H模式等离子体也得到了扩展，并且在较长时间尺度上的壁回收变化已经公布。与AT操作相关的等离子体的开发和研究一直在长放电以及可获得更高NB功率（1000 s）的放电中继续进行。在高βp H模式等离子体中，较高的βN（0.3）维持6.2 s。在反向剪切等离子体中，持续7.4 s的高自举电流分数（fBS）为1.75%。新古典撕裂模（NTM）抑制局部ECCD被发现是更有效的ECRF注入之前的模式饱和。与模式饱和后的注入相比，该模式以更少的功率被抑制。将NTM抑制实验的范围扩展到高βN区，并在βN = 2.5-3时证明了ECCD对m/n = 3/2模的有效抑制。真正的托卡马克等离子体启动没有一个中央螺线管演示。在电流空穴区，它示出，没有方案驱动电流在任何方向上。详细测量的高能离子在空间和能量显示动态变化的高能离子剖面由于集体不稳定性。环形等离子体旋转ELM行为的影响澄清在草地ELM和QH域。偏滤器瓦片中氢同位素的保留进行了分析。
Recent experimental results from steady-state advanced tokamak (AT) research on JT-60U are presented with emphasis on time scales longer in comparison with the characteristic time scales in plasmas. To achieve this, modification of the controls for the operation, heating and diagnostics systems have been carried out. As a result, ∼60 s current flat top and a ∼30 s H-mode are obtained. The long pulse modification has opened a door into a new domain for JT-60U. High normalized beta (βN) of 2.3 is maintained for 22.3 s and 2.5 for 16.5 s in a high-βp H-mode plasma. A standard ELMy H-mode plasma has also been extended and changes in the wall recycling on the longer time scale have been unveiled. The development and investigation of plasmas relevant to AT operation have been continued in long discharges as well as in discharges where higher NB power is available (⩽10 s). Higher βN (∼3) is maintained for 6.2 s in a high-βp H-mode plasma. High bootstrap current fraction (fBS) of ∼75% is sustained for 7.4 s in a reversed shear plasma. Neo-classical tearing mode (NTM) suppression by localized ECCD is found to be more effective with ECRF injection preceding the mode saturation. The mode is suppressed with less power compared to the injection after the mode saturates. The domain of the NTM suppression experiments is extended to the high-βN regime, and the effectiveness of m/n = 3/2 mode suppression by ECCD is demonstrated at βN ∼ 2.5–3. Genuine tokamak plasma start up without a central solenoid is demonstrated. In a current hole region, it is shown that no scheme drives current in any direction. Detailed measurement of energetic ions in both space and energy showed dynamic change in the energetic ion profile due to collective instabilities. The impact of toroidal plasma rotation on ELM behaviour is clarified in the grassy ELM and QH domains. Retention of hydrogen isotopes in the divertor tiles is analysed.