Generation Of Ion Beams On A Steel Surface By Laser Radiation At Various Wavelengths Under The Presence Of An Applied Electric Field

This paper describes the generation of highly stripped ions and high currents in laser produced steel plasma in an applied electric field. A steel target kept under partial vacuum conditions (10-3 mbar) is irradiated with focused Q-switched Nd:YAG laser radiation of various wavelengths with various pulse durations. The evaporated ions were detected at a distance of 40 mm from the target, after passing through a retarding mesh grid. The laser radiation, with peak intensity between 5.35 × 109 to 1 × 1011 W/cm2 creates a dense plasma having a high ionization state. The velocity distribution function of the plasma cloud emitted from the plasma is investigated using a Faraday cup. The dependence of the current signals on various parameters, such as laser power, laser wavelengths, pulse widths and argon (Ar) pressure, is described. In addition the I-V characteristics of the plasma in the presence of glow discharge were studied with and without laser radiation. In general, an increase in the plume current was observed as the mesh voltage is increased, and is related to arc formation. The possibility to find microablation was noted by using Reflection Optical Microscope (ROM). A graph is presented. Velocity distribution function, F(v), versus ion velocity, v, for steel ions received by Faraday cup; without and with laser of wavelenght (λ = 1064 nm, 532 nm, 355 nm, and 266 nm) at constant pressure of 0.2 mbar, Faraday cup voltage of -80 V and power supply voltage of 500 V. © 2006 by Astro Ltd. Published exclusively by Wiley-VCH Verlag GmbH & Co. KGaA