Overview of first Wendelstein 7-X high-performance operation
Overview of first Wendelstein 7-X high-performance operation
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DOI：
10.1088/1741-4326/ab03a7
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发表时间：
2019-11-01
期刊：
影响因子：
3.3
通讯作者：
Zuin, M.
中科院分区：
文献类型：
--
作者：
Klinger, T.;Andreeva, T.;Zuin, M.
经过优化的超导仿星器装置温德尔斯坦7-X（长半径R = 5.5 m，短半径a = 0.5 m，等离子体体积为30 m（3））在组装了石墨隔热屏和10个惯性冷却的岛式偏滤器模块后重新开始运行。本文报告了第一次高性能等离子体操作的结果。氦中辉光放电调节和ECRH调节放电对密度和边缘辐射控制很重要。等离子体密度为1-4.5 x 10（19）m（-3），中心电子温度为5-10 keV，通常用氢气燃料来实现，通常由辐射崩溃终止。在第一阶段，等离子体密度达到1.4 × 10（20）m（-3），氢芯块注入和氦气燃料。这里，离子被间接加热，并且中心密度为8。10（19）m（-3）时，瞬时实现了3.4 keV的温度，T-e/T-i = 1，这对应于nT（i）（0）tau（E）= 6.4 × 10（19）keV s m（-3），峰值抗磁能量为1.1 MJ，体积平均归一化等离子体压力= 1.2%。通过对第一壁进行硼化，打开了高等离子体密度的常规通路。硼化后，氧杂质含量减少了10倍，碳杂质含量减少了5倍。降低的（边缘）等离子体辐射水平使得常规地获得更高的密度而没有辐射崩溃，例如，在中等ECRH功率下，远高于1 × 10（20）m（-2）线积分密度和T-e = T-i = 2 keV中心温度。X2和O2模式ECRH方案均得到成功应用。用相衬成像诊断仪测量了芯部湍流，观察了弹丸注入过程中湍流的抑制。
The optimized superconducting stellarator device Wendelstein 7-X (with major radius R = 5.5 m, minor radius a = 0.5 m, and 30 m(3) plasma volume) restarted operation after the assembly of a graphite heat shield and 10 inertially cooled island divertor modules. This paper reports on the results from the first high-performance plasma operation. Glow discharge conditioning and ECRH conditioning discharges in helium turned out to be important for density and edge radiation control. Plasma densities of 1-4.5 x 10(19) m(-3) with central electron temperatures 5-10 keV were routinely achieved with hydrogen gas fueling, frequently terminated by a radiative collapse. In a first stage, plasma densities up to 1.4 x 10(20) m(-3) were reached with hydrogen pellet injection and helium gas fueling. Here, the ions are indirectly heated, and at a central density of 8 . 10(19) m(-3) a temperature of 3.4 keV with T-e/T-i = 1 was transiently accomplished, which corresponds to nT(i)(0)tau(E) = 6.4 x 10(19) keV s m(-3) with a peak diamagnetic energy of 1.1 MJ and volume-averaged normalized plasma pressure = 1.2%. The routine access to high plasma densities was opened with boronization of the first wall. After boronization, the oxygen impurity content was reduced by a factor of 10, the carbon impurity content by a factor of 5. The reduced (edge) plasma radiation level gives routinely access to higher densities without radiation collapse, e.g. well above 1 x 10(20) m(-2) line integrated density and T-e = T-i = 2 keV central temperatures at moderate ECRH power. Both X2 and O2 mode ECRH schemes were successfully applied. Core turbulence was measured with a phase contrast imaging diagnostic and suppression of turbulence during pellet injection was observed.