Dynamics of the spectral behaviour of an ultrashort laser pulse in an argon-gas-filled capillary discharge-preformed plasma channel

¹ Utsunomiya University, Department of Advanced Interdisciplinary Sciences, Yoto 7-1-2, Utsunomiya, Japan
² Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Japan
³ Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya str. 25, Moscow, Russia
⁴ University of Nevada, Department of Physics, Mail Stop 220, Reno, Nevada, USA
⁵ Osaka University, Graduate School of Engineering, 2-6 Yamada-oka, Suita, Osaka, Japan

^a e-mail: higashi@cc.utsunomiya-u.ac.jp

Published online: 15 November 2013

Abstract

We have reported the argon plasma waveguide produced in an alumina (Al₂O₃) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 10¹⁶  W/cm². A one-dimensional magnetohydrodynamic (MHD) code was used to evaluate the average degree of ionization of Ar in the preformed plasma channel. The spectrum of the propagated laser pulse in the Ar plasma waveguide was not modified and was well reproduced by a particle-in-cell (PIC) simulation under initial ion charge state of Ar³⁺ in the preformed plasma waveguide. The optimum timing for the laser pulse injection was around 150 ns after initiation of a discharge with a peak current of 200 A.