An electrical detection of the fluctuating plasma of laser welding with a passive probe

A laser-induced plasma is an important physical phenomenon that plays an important role in the laser welding process and the quality of the weld. The objective of this study is to obtain a fundamental knowledge of this physical process. A new detecting method of using a passive probe to detect the electric signals of the plasma plume is proposed and developed. This is demonstrated to be a feasible method for the measurement of electron temperature referring to the electron temperature calculated from the synchronous spectral signal. From an analysis of the wave patterns of the electric signal, the signal can reflect the eruption moment of the fluctuating plasma. The experimental results demonstrate that if the probe is placed appropriately, the designed electric probe can be used to reflect the real-time fluctuation of electron temperature of the generated plasma.