Characteristic Analysis Of AC Arc In Water

Nowadays, arc has been used by people very widely, for instance, in field of metallurgy, weld and incision, spraying, and electric pushing. However, at present, plasma arc generally uses gas (argon, nitrogen, air) as its work medium, but fewer researches focused on plasma arc generated in liquid. Discharge in water is a new subject after 20 century 50's, and research on water plasma arc is valuable in theory and application.In this thesis, generator system of ac arc in water is established, and signal detecting circuit is designed. Voltage and current waveform are collected, and the V-I characteristics of work medium and arc are made. According to observing the process of arc striking and the reference of liquid breakdown traditional theory, the breakdown theory of water under low ac voltage is supposed. The relationship of arc striking voltage and electrode material is analyzed. Spectral diagnosis system is established, because the arc plasma in water meet a criterion of Local Thermal Equilibrium (LTE) characteristic, and according to the measurement of spectral lines relative intensity of arc plasma in water, which electron excitation temperature was obtained by double-line method, it is 7643K while the arc power was 750W; its concentrations of electron, H, H+, O and O+ are got by Saha Equation method, while the arc power is 750W, they are respectively 6.65×10²¹m^-3, 9.1350×10²¹m^-3, 4.4333×10²¹m^-3, 4.5675×10²¹m^-3, 2.2167×10²¹m^-3. Otherwise, the relationships of above parameters and arc power are obtained. To making the temperature of arc pillar distribute more smoothly, the electrode model is improved, and arc is applied with equal transverse magnetic field and air stream. According to the voltage and current waveform, the influences of transverse magnetic field and air stream to arc are analyzed. Using spectral diagnosis technology, the electron excitation temperature and concentrations of electron are measured, and the influence of transverse magnetic field to them is analyzed. The results obtained in this thesis will be the basic for study and application of ac arc in water. This research also has some reference value for designing other AC arc equipment.