抄録
Helium microwave-induced plasma (He-MIP) for nonmetal elements analysis was generated by a 2.45 GHz microwave power (∼1 kW) with the Okamoto cavity of the surface wave mode at atmospheric pressure. Effects of the main parameters of the cavity such as a thickness (direction of the electric field) of the cavity, the width of a ring-slot and the position of a discharge tube (torch) on an excitation temperature and the analytical signals were investigated. The excitation temperature and an electron density of the plasma as a parameter of the microwave power, and the plasma and carrier gas flow rates were measured. With 600 watt input microwave power, the excitation temperature of high energy part of 7000 K and the electron density of 2.4×1014/cm3 were obtained. An aqueous solution of NaF was introduced into the center of the annular He-MIP and the F I (685 nm, 14.5 eV) signal was detected, and the effects of microwave power and the gas flow rates on the signal were studied. The detection limit of 60 ppb for fluorine was obtained.
