Temperature distributions of radio-frequency plasma in water by spectroscopic analysis

Abstract

Distributions of emission intensity from radicals, electron temperature, and rotational temperature at a radio frequency of 27.12 MHz plasma in water are clarified by detailed spectroscopy measurement. Through this investigation, the following were observed. The points of maximum emission intensity of Hα, Hβ, O (777 nm), and O (845 nm) are almost the same, while that of OH shifts upward. The electron temperature decreases, while the rotational temperature increases with pressure. The distribution of the electron temperature changes at a threshold pressure, which is concerned with a change in the electron discharge mechanism. The self-bias of the electrode changes from a negative to positive at a threshold pressure. The point of the maximum rotational temperature of OH radicals shifts to approximately 1 mm above that for the maximum intensity of OH emission.

Effective Dissolution of Biomass in Ionic Liquids by Irradiation of Non-Thermal Atmospheric Pressure Plasma

“…1. The optical emission spectrum confirmed the presence of active species, OH (309 nm), Hα (656 nm), and O (777 nm) [34,35] , generated by the plasma (Fig. 2).…”

A Novel Method for Producing Hydrogen from a Hydrocarbon Liquid Using Microwave In-liquid Plasma

“…There have been many reports which focused on bubbles in relation to the generation of plasma in a liquid by a variety of methods [32][33][34][35]. The behavior of bubbles and plasma generated by high frequency waves and microwaves is observed using a high speed camera [36][37][38][39]. Microwave plasma is generated when the electrode is heated to the saturation temperature of n-dodecane [33,40].…”

Application of a Non-thermal Atmospheric Pressure Plasma Jet to the Decomposition of Salicylic Acid to Inorganic Carbon

“…The main peaks detected in the spectrum were OH (309 nm), Hα (656 nm), Hβ (486 nm), O (777 nm), and He (589 nm). 21,22 The strong OH band indicates that OH radical was generated in the gas phase. Since the OH band was dominant in the spectrum, this plasma is expected to be suitable for the degradation of salicylic acid.…”