Use of one dimensional Dα camera to measure edge electron density gradients
Use of one dimensional Dα camera to measure edge electron density gradients
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使用一维Dα相机测量边缘电子密度梯度
DOI：
10.1063/1.1537041
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发表时间：
2003
影响因子：
1.6
通讯作者：
M. Walsh
中科院分区：
文献类型：
--
作者：
M. Tournianski;P. Carolan;N. Conway;G. Counsell;E. Arends;M. Walsh
从L模等离子体到H模等离子体跃迁的一个最明显的特征是边缘密度梯度的陡化。通常可以观察到伴随而来的可见光辐射变窄，通常是由巴尔默Dα发射主导的。典型地，L模的Dα发射率宽度为4-6厘米，与ELMS相似，而H模主等离子体的发射率宽度为1-3厘米，与典型的边缘Ne尺度长度相当。一种从径向Dα发射率分布变窄中提取电子密度的方法是在启动装置上首创的，并在MAST上得到了进一步发展。它利用了氢的电离速率和发射速率对电子温度的近乎不敏感的特性，温度远远超过电离势(13.6 eV)。Dα发射率剖面由线阵相机(Δt=12 5 μS，2 5 6象素)记录的视线积分强度的空间反演得到。300点汤姆逊散射诊断已被用作比较实验数据的一个标尺。
One of the clearest signatures of the transitions from L- to H-mode plasmas is the steepening of the edge density gradient. A concomitant narrowing of the visible radiation, usually dominated by Balmer Dα emission, is generally observed. Typically, the Dα emissivity width is 4–6 cm for the L-mode, similar for ELMs, and 1–3 cm for H-mode MAST plasmas, comparable with typical edge ne scale lengths. A means of extracting electron densities from this narrowing of the radial Dα emissivity profile was pioneered on the START device and developed further on MAST. It takes advantage of the near insensitivity to electron temperature of both the ionization and emission rates of hydrogen at temperatures well in excess of the ionization potential (13.6 eV). The Dα emissivity profile is obtained from spatial inversion of line-of-sight integrated intensities recorded by a linear camera (Δt=125 μs, 256 pixels). The 300 point Thomson scattering diagnostic has been used as a yardstick in comparing experimental data from a ...