Temperature measurements in plasmas generated by using lasers at different intensities

Abstract

The temperature of laser-generated pulsed plasmas is an important property that depends on many parameters, such as the particle species and the time elapsed from the laser interaction with the matter and the surface characteristics. Laser-generated plasmas with low intensity (<1010 W/cm2) at INFN-LNS of Catania and with high intensity (>1014 W/cm2) in PALS laboratory in Prague have been investigated in terms of temperatures relative to ions, electrons, and neutral species. Time-of-flight (ToF) measurements have been performed with an electrostatic ion energy analyzer (IEA) and with different Faraday cups, in order to measure the ion and electron average velocities. The IEA was also used to measure the ion energy, the ion charge state, and the ion energy distribution. The Maxwell–Boltzmann function permitted to fit the experimental data and to extrapolate the ion temperature of the plasma core. The velocity of the neutrals was measured with a special mass quadrupole spectrometer. The Nd:Yag laser operating at low intensity produced an ion temperature core of the order of 400 eV and a neutral temperature of the order of 100 eV for many ablated materials. The ToF of electrons indicates the presence of hot electron emission with an energy of ∼1 keV.