Electrons emission from laser induced metallic plasmas

Localized behavior of laser induced metallic plasmas has been investigated using Langmuir probe as an electrostatic diagnostic tool. A Q-switched Nd:YAG pulsed laser (1064 nm, 12 ns, 1.1 MW) is tightly focused on metal targets (Cu, Zn, Cd, Ag, Pt and Au) having dimensions 2 × 2 × 0.2 cm3 under vacuum ∼10−3 torr. The varying biasing voltages are applied to Langmuir probe. The electric signals are recorded on two channel 200 MHz digital storage oscilloscope (UNI T - UTT 2202). A comparison shows strong dependence of electron parameters (temperature, density, Debye length, plasma frequency and number of particles in Debye sphere) in plasmas on target materials' properties (atomic number, surface binding energy etc.). The maximum values for electron density (8.08502 × 1017 m−3), Debye length (8.07066 × 10−4 m), plasma frequency (5.19627 × 1010 Hz) are found for silver and copper metals, respectively, where as the electron temperature shows variation in this trend i.e. maximum value (1.36581 × 106 K) for cadmium and minimum value is for gold (1.0008 × 105 K). the maximum value of number of particles in Debye length at +15 V (1.47 × 1026) for Pt and that minimum for Ag (2.1355 × 107).