Development of Low-Fregnency Induction Thermal Plasma for Cluster Synthesis

1998年，在该项目的第三年，也是最后一年，成功地用低频450 kHz、功率50 kW的MOSFET逆变电源产生了宽区域感应等离子体，其反应区域直径为150 mm，长度为150 mm，使我们能够高速加工或合成材料。用<60>Ar、He和CO_2等离子体诱导热等离子体合成了C_（10）富勒烯。实验结果表明：1）晶体管逆变电源可用于建立频率为450 kHz的电感耦合等离子体。在30 kW的功率水平下，可以在Ar、He和CO2气体环境中产生多种等离子体。与Ar和He等离子体相比，CO2等离子体具有约10，000 K的相对较高的温度。2）这些感应热等离子体对于高达10 g/min的冷碳粉注入速率足够稳定，这是足够高的量以高速率产生C_<60>团簇。3）在几种气体种类条件下进行的实验中，Ar/He惰性气体等离子体具有最高的C_2<60>合成率，而解离CO_2气体等离子体没有C_2的合成<60>。结果表明，自由基C原子和C_2分子的强猝灭效应是合成这种高阶富勒烯材料的必要条件。

In the third and final year of the project, 1998, a wide area induction plasma was successively generated by using MOSFET inverter power supply with a low frequency of 450 kHz and a power of 50 kW.The reaction area of the plasma is as wide as 150-mm diameter and 150-mm length, which enable us the high speed processing or synthesis of materials. C_<60> fullurene synthesis was carried out by using Ar, He and CO_2 induction thermal plasmas. Remarkable results are as follows.1) The transistor inverter supply was found to be useful to establish the inductively coupled plasma with a frequency of 450 kHz. At a power level of 30kW, several kinds of plasma can be generated in Ar, He and CO2 gas circumstance. The CO2 plasma was found to have relatively high temperature around 10,000 K compared to Ar and He plasma.2) These induction thermal plasmas were sufficiently stable for the injection of cold carbon powders up to a rate of 10 g/min, which is high enough quantity to produce the C_<60> cluster with a high rate.3) Among the experiments carried out under several conditions with respects to the gas sort, pressure and the power of plasma, Ar/He noble gas plasma showed the most highest C_<60> synthesis rate, while the dissociative CO_2 gas plasma showed no synthesis of C_<60>. The results indicate that a strong quenching effect of the radical C atom and C_2 molecule is essential for the synthesis of such high order fullurene materials.