High-speed synthesis of fullerences by using low-frequency induction thermal plasma with pulse-modulated mode.

(1)利用大功率感应热等离子体合成富勒烯及各种参数对产物的依赖性。采用大功率感应热等离子体合成富勒烯，研究了各参数对合成产物的影响。参数包括：(a)气体种类；(b)压力；(c)输入功率；(d)动力材料；(e)产品收集位置。通过研究，发现以下条件更适合富勒烯的合成：(a)以He为主要环境气体，而不是Ar； (b)压力低于20kPa，而不是50或67 kPa； (c)输入功率低于30kW，而不是50或70kW； (d)与c +Fe， c +Ni-Co和纯c相比，c +Si材料功率更大；(e)距离等离子炬900mm远，而不是近。对反应室内的流动场和温度场进行了数值模拟。结果表明，He的使用增加了火炬轴上的温度梯度，从而提高了气体的冷却效率。低压增大了轴向流速度，提高了气体的冷却效率。(2)脉冲调制感应热等离子体火炬研制及热等离子体动态响应研究。提出了一种新型的脉调感应热等离子体维持系统。该系统具有额定功率为50kW，工作频率为450kHz的MOSFET逆变电源。研究了附加气体对Ar基感应热等离子体的动态响应特性。结果表明，co2包合物显著降低了脉冲调制感应热等离子体的工作区域和动态响应。这种脉冲调制的感应热等离子体可用于通过高速冷却和加热合成富勒烯。

(1) Synthesis of fullerenes using high-power induction thermal plasma and dependence of various parameters on the products. Fullerene synthesis were made using high-power induction thermal plasma and dependence of various parameters on the products was investigated. The parameters are as follows: (a) gas kind, (b) pressure, c input power, (d) power materials, (e) location for collection of the products. Through the investigation, the following conditions were found to be preferable for fullerene synthesis: (a) He as main ambient gas rather than Ar, (b) Lower pressure of 20kPa than 50 or 67 kPa, c Lower input power of 30kW than 50 or 70kW, (d) C+Si material power compared with C+Fe, C+Ni-Co and pure C, (e) long-distance location of 900mm from plasma torch rather than close location. Further investigation was made by numerical simulation of flow and temperature fields in a reaction chamber. This result indicates that use of He increases temperature gradient on the torch axis, which means the high cooling efficiency of gas. Also, it was found that low pressure increases axial flow velocity, which causes high cooling efficiency of gas.(2) Development of pulse-modulated induction thermal plasma torch and investigation of dynamic response of thermal plasma. A novel system was developed to sustain pulse-modulated induction thermal plasma with amplitude-modulated coil-current. This system has a MOSFET inverter power supply rated at a power of 50kW and a operating frequency of 450kHz. Dynamic response characteristics were investigated for Ar based induction thermal plasma with additional gases. This result indicates that C02 inclusion markedly lowers both operating region and dynamic response of pulse-modulated induction thermal plasma. This pulse-modulated induction thermal plasma is available for fullerene synthesis by high-speed cooling and heating.