Enhancement of laser-induced breakdown spectroscopy signals using both a hemispherical cavity and a magnetic field

摘要

A pair of permanent magnets and an aluminum hemispherical cavity (diameter: 11.1 mm) were both used to confine plasmas produced by chromium targets in air using a KrF excimer laser in laser-induced breakdown spectroscopy. A significant enhancement factor of about 24 in the emission intensity of Cr lines was acquired at a laser fluence of 6.2 J/cm~2 using the hybrid confinement. In comparison, an enhancement factor of only about 12 was obtained with just a cavity. The Si plasmas, however, were not influenced by the presence of magnets as Si is hard to ionize and, hence, has less free electrons and positive ions. The hybrid confinement mechanism is discussed using shock wave theory in the presence of a magnetic field.