Influences of the Arc Chamber Length on the Jet Characteristics of Laminar Plasma Torch

Laminar plasma jet (LPJ) which is generated by laminar plasma torch (LPT) has more advantages than the turbulent plasma jet on applications, such as materials processing and plasma spraying. The jet characteristics of LPT are influenced by many factors, e.g., the working parameters, plasma torch construction, gas injection angle, and arc chamber length. A lot of research has been done in recent years. However, a better understanding of how the arc chamber length influences LPT's jet characteristics is still required. Thus, this paper aims to study the influences of the arc chamber length on LPT's jet characteristics. The first part mainly focuses on the introduction of the LPT setup we used in this paper, and this setup can switch the chamber length from 67 to 84 mm or 101 mm by adjusting interelectrodes' number from 3 to 5. The second part introduces the methods and equipment used in this paper. The last part is results and discussions. The results show that when the arc chamber length increases from 67 to 84 mm and from 84 to 101 mm: 1) the corresponding arc voltage and working power of the experimental LPT increase 20% and 12%, respectively; 2) the corresponding thermal efficiency increases 30% and 8%, respectively; 3) the corresponding mean specific enthalpy of the LPJ increases 50% and 20%, respectively; and 4) on the one hand, the LPT's jet length increases slightly with increasing the arc chamber length, and on the other hand, it increases first and then decreases with increasing the working gas; additionally, the plasma jet changes from laminar flow state to turbulent flow state.