Laser Spectroscopy and Sensing

Enhancement of Plasma Emission by Microwave Heating

The goal of this project is to achieve the best enhancement of the plasma emission for laser-induced breakdown spectroscopy (LIBS) using microwave radiation and understand the physics behind the enhancement. The experimental setup is similar to the conventional LIBS setup, except that a microwave cavity is put adjacent to the sample. The function of the microwave cavity is to sustain a focused microwave with its focal spot overlapping the laser-induced plasma.

The key to the enhancement is how energy is transferred from the microwave to the plasma. If the electromagnetic wave can penetrate the plasma, strong absorption will occur as long as the angular frequency ω is smaller than the plasma frequency. The applications of this LIBS configuration are the detection of low concentration emitters in the plasma and formation of molecular products .