Properties of gravity-free arc discharge and its application to production of high-quality carbon annotates

1)在12 m高的立式摇摆塔上进行的实验在无重力条件下，电弧的发射强度增强，电弧体积增大，电极上的弧斑稳定。2）流体模拟计算了实验条件下气体的温度场和膨胀速度矢量随时间的演化。在无重力条件下，热气体区缓慢单调扩展。当温度梯度低时，反应时间增加。在正常重力条件下，稳态热对流（速度约为1 m/s）在1 s内立即建立。这些计算结果与实验结果吻合较好。3）无重力条件下碳纳米管的生成在无重力条件下，（a）碳烟的生成速率增加，（B）碳烟中单壁碳纳米管的含量增加了一倍左右，碳纳米管束的厚度增加，（c）长度估计为10-100微米，（d）纳米管变胖。4）纯化通过氧等离子体纯化纳米管样品。5）物理特性制造出纳米管颗粒，硬度高。6）在展览会上的展示2005年9月在东京举行的“创新日本2005”展览会上展示了该成果。

1)Experiment by a 12-m-high vertical-swing-tower Under the gravity-free condition, the emission intensity from the arc is enhanced, the volume of the arc is increased and the arc spot on the electrodes is stabilized.2)Fluid simulation Time evolution of the temperature contour and expansion velocity vectors of the gas was calculated under the experimental condition. Under the gravity-free condition, the hot gas region expands slowly and monotonically. As the temperature gradient is low, the reaction time is increased. Under the normal gravity condition, the steady-state heat convection (with speed of about 1 m/s) is immediately established within 1 s. These calculation results are in good agreement with the experimental results.3)Production of nanotubes under the gravity-free condition Under the gravity-free condition, (a)production rate of the soot increases, (b)content of single-walled carbon nanotubes in the soot is about twice, and the thickness of the nanotube-bundles increases, (c)the length is estimated to be 10-100 micro meter, (d)the nanotubes become fatter.4)Purification By the oxygen plasma the nanotube sample is purified. By using the spark-gap method, conductive carbon particles are removed.5)Physical properties The nanotube pellet is produced, and its hardness is strong.6)Presentation in an exhibition The results were presented in the exhibition (Innovation Japan 2005, Sep. 2005) held in Tokyo.