Initial operation of the divertor Thompson scattering diagnostic on DIII-D
Initial operation of the divertor Thompson scattering diagnostic on DIII-D
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DIII-D 上偏滤器 Thompson 散射诊断的初始操作
DOI：
10.1063/1.1147893
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
R. Stockdale
中科院分区：
文献类型：
--
作者：
T. Carlstrom;C. Hsieh;R. Stockdale
本文报道了托卡马克偏滤器区n{sub e}和T{sub e}的首次汤姆逊散射测量。这些数据被用作边界物理代码，如UEDGE和DEGAS的输入，并基准这些代码的预测能力。这些测量也有助于表征托卡马克中断。Nd：YAG激光（20 Hz，1 J，15 ns，1064 nm）垂直通过DIII-D托卡马克的下偏滤器区。一个定制的非球面收集透镜（f /6.8）将靶板上方1-21 cm处的激光束成像到8个空间通道中，垂直分辨率为1.5 cm，径向分辨率为0.3 cm。偏滤器区域的2D映射通过径向地扫描偏滤器X点位置通过固定的激光束位置来实现。光纤将光传送到多色仪，多色仪的干涉滤光片已针对低T{sub e}测量进行了优化。硅雪崩光电二极管测量散射光和等离子体背景光。温度和密度通常分别在5-200 eV和1 - 10 × 10{sup 19} m{sup -3}的范围内。在分离的等离子体中观察到低温，T{sub e} 8 x 10 {sup 20} m{sup -3}。背景光水平一直不是一个重大问题。激光杂散光的减少允许瑞利校准。由于接近困难，不能使用容器内真空对准靶。相反，原位激光对准监视器为每个激光脉冲提供对准信息。结果进行了比较，朗缪尔探针测量，发现良好的协议，除了高n{子e}和低T{子e}的区域测量汤姆逊散射。
The first Thomson scattering measurements of n{sub e} and T{sub e} in the divertor region of a tokamak are reported. These data are used as input to boundary physics codes such as UEDGE and DEGAS and to benchmark the predictive capabilities of these codes. These measurements have also contributed to the characterization of tokamak disruptions. A Nd:YAG laser (20 Hz, 1 J, 15 ns, 1064 nm) is directed vertically through the lower divertor region of the DIII-D tokamak. A custom, aspherical collection lens (f /6.8) images the laser beam from 1-21 cm above the target plates into eight spatial channels with 1.5 cm vertical and 0.3 cm radial resolution. 2D mapping of the divertor region is achieved by sweeping the divertor X-point location radially through the fixed laser beam location. Fiber optics carry the light to polychromators whose interference filters have been optimized for low T{sub e} measurements. Silicon avalanche photo diodes measure both the scattered and plasma background light. Temperatures and densities are typically in the range of 5-200 eV and 1 - 10 x 10{sup 19} m{sup -3} respectively. Low temperatures, T{sub e} 8x10{sup 20} m{sup -3} have been observed in detached plasmas. Background light levels have not been a significant problem. Reduction of the laser stray light permits Rayleigh calibration. Because of access difficulties, no in-vessel vacuum alignment target could be used. Instead, an in situ laser alignment monitor provides alignment information for each laser pulse. Results are compared with Langmuir probe measurements where good agreement is found except for regions of high n{sub e} and low T{sub e} as measured by Thomson scattering.