Pulse Operated MIP-MASS Sectroscopy

本工作研制了一种新型的微波诱导等离子体(MIP)源，它具有轴向变径放电管，能够将液体气溶胶直接引入等离子体。用有限元方法计算了MIPTM010腔内的谐振频率和电场。该变轴管极大地增强了等离子体放电管边缘和中心的电场，为了验证新研制的放电管的作用，测量了电子数密度和等离子体温度。结果表明，密度和温度都有所提高。因此，计算似乎是定性的。对等离子体温度和电子数密度的测量是在各种操作条件下进行的。水样引入后，观察到的温度和电子数密度显著增加，但Ar的发射强度降低。实验结果表明，在测量所采用的操作条件下，局部热力学平衡不一致，原子物种与高能电子碰撞引起的激发和电离占主导地位。使用新的无制冷系统的MIP源，即使在直接引入液体气溶胶的情况下，也可以获得相对较低的前向微波功率(-20W)的稳定等离子体。测量了载气流量、等离子体气体流量和前向功率对CD谱线强度的影响，得到了最合适的工作条件。为了评价新型分子印迹聚合物作为原子发射光谱(AES)的激发源，还测量了几种元素的线性动态范围和检出限。

In this work a new Microwave Induced Plasma(MIP) source with an axially-varied bore discharge tube was developed, whiche is able to introduce liquid aerosols directly into the plasma. The resonant frequency and electric field in the MIP TM010 cavity were calculated using the finite element method. The axially-varied tube highly enhanced the electric field on the edge an the center of the plasma discharge tube.To confirm the effect of the discharge tube newly developed, the electron number density and the plasma temperatures were measured. The result shows that the density and the temperatures were both elevated. Accordingly, the calculation seems to be qualitatively adequate.The measurements on plasma temperatures and on electron number density were made at a variety of operating conditions. Observed temperatures and electron number density exhibit significant increase, but decrease of argon emission intensity, upon the aqueous sample introduction. Experimental results suggest that local thermodynamic equilibrium is not consistent and excitation and ionization of atomic species due to collision with high energy elactron is dominant under the operating conditions employed for the measurements.Using the new MIP source without cooling system, a stable plasma at relatively low forward microwave power (-20W) was obtained even with direct introduction of liquid aerosols. The effects of carrier gas flow rate, plasma gas flow rate and forward power on the intensity of Cd line were measured and the most suitable operating conditions were obtaind. To evaluate the new MIP as an excitation source for atomic emission spectrometry(AES), the linear dynamic range and the detection limits for several elements were also measured.