The effect of laser wavelength on heating of ablated carbon plume

The effect of laser wavelength on heating of the ablated carbon plume is studied. The plasma absorption coefficients are calculated in order to analyze the results and an experiment is conducted using the first, second, and third harmonic of a Nd:YAG laser. Plasma temperature and electron density in the early phase of expansion in vacuum are studied as a function of distance from the target. The calculations show that the ratio between absorption coefficients for 1064, 532, and 355 nm is approximately 9:2:1. The experimental results do not agree well with the theoretical predictions. Indeed, the plasma temperatures are highest in the case of 1064 nm but no clear differences between 532 nm and 355 nm have been found.