Author(s)

Mohamed Abd El-Hameid Mahmoud, Yosr Ez El Din Gamal

Department of Physics, Faculty of Science, Sohag University, Sohag, Egypt.
Department of Physics, Girls’ Faculty of Science, King Abdul-Aziz University, Jeddah, KSA.

An investigation of the resonant interaction of the rubidium atoms with an intensity (10 kWcm^-2 ≤ I ≤ 2 MWcm^-2) and a wavelength close to that of the D₁ and D₂ transitions of the rubidium atom (5S_1/2 → 5P_3/2 or 5S_1/2 → 5P_1/2, λ_D1 = 780 nm, λ_D2 = 795 nm), which has passes through rubidium vapor with density (10¹¹ - 10¹⁴ cm^-3) been studied theoretically. The system of equations describing the processes of Collisional ionization and multiphoton ionization of rubidium vapour resonantly excited with nanosecond pulsed laser is solved. The dependence of the ion density on the laser intensity and the atomic density of rubidium are considered. The result of calculations revealed that, both quadratic ion density dependence on laser intensity and linear behaviour of the ion density versus rubidium density for 5S_1/2 → 5P_3/2 transition is due to photoioization process. In contrast, for 5S_1/2 → 5P_1/2 transition, the ion density dependence is nonlinear and indicates that the collisional processes play the major contribution in the total ionization. Also, the obtained results showed reasonable agreement with the experimentally measured values of the ion density dependence given by Bakhramov et al. In addition, the analysis of mutual competition between the different ionization processes considered for the ion yield as a function of both laser intensity and atoms density are also presented this work.

Laser; Plasma; Collisional Ionization; Electron Energy Distribution Function; Photoionization; Rubidium

M. Mahmoud and Y. Gamal, "Computational Study of Resonantly Ionizing Rubidium Vapor by Nanosecond Laser Pulses," Journal of Modern Physics, Vol. 3 No. 9, 2012, pp. 927-934. doi: 10.4236/jmp.2012.39121.