Production of High-Power Microwave-Induced Helium Plasma at Atmospheric Pressure for Trace Element Analysis

研制了常压下大功率（~ 1 kW, 2.45 GHz）环形微波诱导氦等离子体，用于测定水溶液中的非金属。等离子体是由冈本腔产生的(Y. Okamoto, Anal。Sci. 7(1991) 283)，它被修改为集中能量和低气体流速（101/min）。没有使用外部冷却来稳定等离子体。用超声脱溶冷凝系统将水溶液注入等离子体。电子密度和铁激发温度分别为10^<14>cm3和5000 K。引入NaF形式的氟化物、NaCl形式的氯化物和KBr形式的溴化物会产生强烈的发射，FI（685.6 nm）的检测限为100 ppb， Cl II（479.5 nm）的检测限为100 ppb， Br II（470.5 nm）的检测限为200 ppb。

A high-power (〜1 kW, 2.45 GHz) annular-shaped microwave-induced helium plasma at atmospheric pressure was developed for determination of nonmetals in the aqueous solutions. The plasma was generated by an Okamoto cavity (Y. Okamoto, Anal. Sci. 7 (1991) 283) which was modified to focus the energy and low gas flow rate )101/min). No external cooling was used to stabilized the plasma. An aqueous solution was injected into the plasma by an ultrasonic system with desolvation and condensation. The electron density and iron excitation temperature were on the order of 10^<14>cm3 and 5000 K, respectively. Introduction of aqueous fluoride in the form of NaF, chloride in the form of NaCl, and bromide in the form of KBr produced intense emission and detection limits of 100 ppb for FI(685.6 nm), 100 ppb for Cl II(479.5 nm), and 200 ppb for Br II(470.5 nm) were obtained.