A comparison of the temperatures and electron densities of laser-produced plasmas obtained in air, argon, and helium at atmospheric pressure

Time-resolved measurements of temperatures and electron densities of laser-produced plasmas generated in air, argon, and helium at atmospheric pressure are presented. The plasmas are obtained by the focusing of a Nd:YAG laser on a low-alloyed steel sample. The relative experimental error for temperatures is in the range 0.6%-3% and for electron densities, it is 4.5%. The higher temperatures and electron densities are obtained in argon, and the lower ones are found in helium. The temporal evolution of temperature and electron density in the three gases is compared, showing that a faster decay of both magnitudes takes place in helium.