Annals of R.S.C.B., ISSN:1583-6258, Vol. 25, Issue 6, 2021, Pages. 14496 – 14508
Received 25 April 2021; Accepted 08 May 2021.
Munther B. Hassan1,(a) and Lina Mohammed Hatem2,(b)
(a) 1 Professor, Department of physics, faculty of science, university of Kufa.
(b) Department of physics, faculty of science, university of Kufa.
This paper presents a theoretical study to explain the nonlinear self-focusing of Gaussian laser beam through
magnetized plasma under the non- paraxial ray approximation where the Relativistic nonlinearity is operated.
The theoretical analysis and numerical calculations show that in both cases (longitudinal and transverse
magnetic fields), the increasing of external magnetic field values will lead to increase and enhance the nonlinear
self-focusing of Gaussian laser beam, therefore the intensity will reach in the order of 1018 W.cm-2 or more
which is enough to excite a terahertz radiation by relativistic nonlinearity. The terahertz radiation generation is
depending on the down-conversion of three wave mixing technique and on the fulfilling of the phase matching
conditions between the pump wave (laser beam), plasma wave and generated terahertz wave. The results
showed the self-focused was stronger in the case of the longitudinalmagnetic fieldsthan in thecase of the
transverse magnetic fields and the product THZ was also higher in longitudinal than in the case of the
transverse magnetic fields in non- paraxial region.