Watkins J G, Taussig D, Boivin R L, Mahdavi M A, Nygren R E
Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185, USA.
Rev Sci Instrum. 2008 Oct;79(10):10F125. doi: 10.1063/1.2982423.
Two modular arrays of Langmuir probes designed to handle a heat flux of up to 25 MW/m(2) for 10 s exposures have been installed in the lower divertor target plates of the DIII-D tokamak. The 20 pyrolytic graphite probe tips have more than three times higher thermal conductivity and 16 times larger mass than the original DIII-D isotropic graphite probes. The probe tips have a fixed 12.5 degree surface angle to distribute the heat flux more uniformly than the previous 6 mm diameter domed collectors and a symmetric "rooftop" design to allow operation with reversed toroidal magnetic field. A large spring-loaded contact area improves heat conduction from each probe tip through a ceramic insulator into a cooled graphite divertor floor tile. The probe tips, brazed to molybdenum foil to ensure good electrical contact, are mounted in a ceramic tray for electrical isolation and reliable cable connections. The new probes are located 1.5 cm radially apart in a staggered arrangement near the entrance to the lower divertor pumping baffle and are linearly spaced 3 cm apart on the shelf above the in-vessel cryopump. Typical target plate profiles of J(sat), T(e), and V(f) with 4 mm spatial resolution are shown.
两个模块化的朗缪尔探针阵列已安装在DIII-D托卡马克装置的下部偏滤器靶板上，该阵列设计用于在10秒的暴露时间内处理高达25兆瓦/平方米的热通量。这20个热解石墨探针尖端的热导率比原来DIII-D各向同性石墨探针高出三倍多，质量大16倍。与之前6毫米直径的圆顶形收集器相比，探针尖端具有固定的12.5度表面角度，能更均匀地分布热通量，并且采用对称的“屋顶”设计，以允许在反向环形磁场下运行。一个大的弹簧加载接触区域改善了从每个探针尖端通过陶瓷绝缘体到冷却的石墨偏滤器地板砖的热传导。探针尖端钎焊到钼箔上以确保良好的电接触，安装在陶瓷托盘中以实现电隔离和可靠的电缆连接。新探针在下部偏滤器抽气挡板入口附近呈交错排列，径向间距为1.5厘米，在容器内低温泵上方的架子上线性间距为3厘米。展示了具有4毫米空间分辨率的J(sat)、T(e)和V(f)的典型靶板剖面图。
