Dynamic characteristics and energy analysis of Microwave-induced metal discharge

Small sparks or electric arcs referred to as microwave discharge are generally observed, when the metals are subjected to microwave irradiation. The dynamic characteristics of microwave-induced metal discharge in the work were evaluated by the evolution of discharge intensity, measured using photo-voltage conversion method. An energy analysis method of hydro-thermal exchange was used to measure the generated heat from microwave discharge. The performances of microwave-induced metal discharge were connected to microwave power, metal spices, size and quantity. It was revealed iron exhibited more favorable discharge performance than aluminum and copper. The discharge intensity of iron was 1.66 times and 1.22 times that of aluminum and copper, respectively. The increase of microwave power from 320 W to 480 W led to an enhancement of discharge duration, extending from 5.75 min to 7.25 min. The discharge intensity in the presence of three wires of iron increased by 44.6%, compared to that in the presence of one wire of iron. In spite of an appreciable decrease of discharge intensity with the increase of time, microwave discharge could improve the efficiency from electric energy conversion into heat energy to 48.41%, when utilizing one wire of iron with the length of 4 cm and the diameter of 1 mm at 480 W. The changes of the generated heat with discharge intensity conformed to a stepped attenuation relationship.