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

1)通过12m高的垂直摆动塔在无重力条件下的实验，增强了电弧的发射强度，增大了电弧的体积，稳定了电极上的弧斑。2)计算了实验条件下气体的温度等值线和膨胀速度矢量的流体模拟时间演化。在失重条件下，热气区缓慢而单调地膨胀。温度梯度越低，反应时间越长。在正常重力条件下，在S范围内立即建立了稳态热对流(速度约为1m/S)。这些计算结果与实验结果很好地吻合。3)在无重力条件下，纳米管的产生，(A)烟尘的产率增加，(B)烟尘中单壁碳纳米管的含量约为两倍，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)氧等离子体净化纳米管样品。通过使用火花隙方法，去除了导电碳颗粒。5)物理特性纳米管颗粒被生产出来，其硬度很高。6)在一个展览中展示结果在东京举行的展览(创新日本2005,2005年9月)中展示。

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.