Emission enhancement of laser-induced breakdown spectroscopy by increasing sample temperature combined with spatial confinement

To enhance spectral intensity in laser-induced breakdown spectroscopy, increasing the sample temperature and spatial confinement were used simultaneously to improve optical emission of plasmas induced from silicon target using a Nd:YAG laser pulse in air. The sample was uniformly heated to temperatures ranging from a low temperature (25 degrees C) to a high temperature (250 degrees C) with laser energy of 60 mJ, and a cylindrical cavity with a diameter of 6 mm and a depth of 6 mm was used to confine the plasma. The results illustrated that as the sample temperature increased, the spectral intensity of plasma without spatial confinement appeared to saturate at a sample temperature of 150 degrees C. When the cylindrical cavity was present, the spectral intensity increased monotonically along with the sample temperature. The enhancement effect of combining spatial confinement and increasing the sample temperature was stronger than that of spatial confinement or increasing the sample temperature alone. The experimental results indicated that the optical emission intensity can be further improved by combining the two enhancement effects.