Spectroscopic diagnostics of plasma jet in micro-detonation of striking arc machining of engineering ceramics

•MDSAM is a newly developed energetic beam machining technology for ceramics.•Micro-detonation plasma jet is studied by the method of spectroscopic diagnostics.•The electron density is high enough to meet the LTE criterion.•The silicon nitride is decomposed under the highest temperature of 11,986 K.

Micro-detonation of striking arc machining (MDSAM) is a newly developed energetic beam machining technology for engineering ceramics. During machining process, its energy exports with the micro-detonation plasma jet. In this paper, spectroscopic diagnostics is performed to analyze the internal physical state of the micro-detonation plasma jet and an experimental test is employed to study the effect of plasma jet on the silicon nitride ceramics. The Stark broadening method was used to get the electron density and the electron temperature was measured by line intensity method. The results showed that the electron density of plasma is in the range of 1016–1017 cm−3 and meets local thermal equilibrium (LTE). During measuring the electron temperature, the emission line of N element was observed and the line intensity method was used. With the fixed machining parameters of MDSAM, the temperature of the plasma is 11,986 K. The machining test showed that the machined surface of the silicon nitride ceramics was covered with a loose recast layer. The study provides an important reference to reveal the machining mechanism for MDSAM.