Generation of kinetic Alfvén wave and whistler waves by parametric decay of high power laser in laser–plasma interaction

Abstract

In this paper, we report theoretical modeling for parametric decay instability of the high-intensity elliptically polarized laser beam [pump wave, (ω0)]. A wave–wave interaction model is investigated, based on the decay of the high-intensity elliptically polarized laser (ω0) into an oblique whistler wave (OWW, (ω1)) and a kinetic Alfvén wave (KAW, (ω2)). The importance of oblique whistler waves (OWWs, (ω1)) and kinetic Alfvén waves (KAWs, (ω2)) similar to solar wind spectra [Chatterjee et al., Nat. Commun. 8, 15970 (2017)] has been pointed out, as a means to understand the turbulent magnetic field amplification, implicating electron and ion dynamics [Chatterjee et al., Nat. Commun. 8, 15970 (2017); Tzeferacos et al., Nat. Commun. 9, 591 (2018); Meinecke et al., Proc. Natl. Acad. Sci. 112, 8211 (2015); Mondal et al., Proc. Natl. Acad. Sci. 109, 8011 (2012); Romagnani et al., Phys. Rev. Lett. 122, 025001 (2019); Perri et al., Phys. Rev. Lett. 109, 191101 (2012); and Adak et al., Phys. Rev. Lett. 114, 115001 (2015)]. In the nonlinear stage, the decay instability is expected to attain the turbulent state, via a cascade process or filamentation/modulation instability (oscillating two stream instability). Therefore, in the present paper, we have considered the first part of this research, namely, the beating mechanism (ω2=ω0−ω1), induced due to the nonlinear interaction of elliptically polarized laser velocity and oblique whistler wave density perturbation. The nonlinear saturation will be conferred in future investigations. Besides turbulence, the relevance of the present work to terahertz radiation generation [Singh et al., Europhys. Lett. 104, 35002 (2013); Dewan et al., Phys. Plasmas 25, 103105 (2018); Singh et al., Phys. Plasmas 18, 022304 (2011); M. Singh and R. P. Sharma, Contrib. Plasma Phys. 53(7), 540–548 (2013); Adak et al., Phys. Rev. Lett. 114, 115001 (2015); G. Brodin and L. Stenflo, Contrib. Plasma Phys. 54, 623 (2014); L. Stenflo, Phys. Scr. T50, 15–19 (1994); Li et al., Phys. Rev. E 84, 036405 (2011); L. Stenflo, Phys. Scr. T107, 262 (2004); and R. Boyd, Nonlinear Optics, 3rd ed. (Elsevier, 2008), Chap. 2] and fast ignition laser fusion [Kumar et al., arXiv:1804.02200 (2018)] by ion heating has been emphasized. The coefficients for the nonlinear coupling pertaining to this parametric decay process and the growth rate of the decay instability are investigated.