A new method of optical guidance by the implosion phase of a fast Z-pinch discharge in a gas-filled capillary is proposed. An imploding plasma column has a concave electron-density profile in the radial direction, just before a stagnation phase driven by a converging current sheet and a shock wave. The feasibility of optical guidance of a high-intensity (>1 × 10<sup>17</sup> W/cm<sup>2</sup>) Ti:sapphire laser pulse by use of this method over a distance of 2 cm, corresponding to 12.5 times the Rayleigh length, has been experimentally demonstrated. The guiding-channel formation process was directly probed with a He–Ne laser beam. The electron density in the fully ionized channel was estimated to be 2.0 × 10<sup>17</sup> cm<sup>-3</sup> on the axis and 7.0 × 10<sup>17</sup> cm<sup>-3</sup> on the peaks of the channel edge, with a diameter of 70 μm, as indicated by the experimental results, which were corroborated by a magnetohydrodynamics simulation.
© 2000 Optical Society of America
Tomonao Hosokai, Masaki Kando, Hideki Dewa, Hideyuki Kotaki, Syuji Kondo, Noboru Hasegawa, Kazuhisa Nakajima, and Kazuhiko Horioka, "Optical guidance of terrawatt laser pulses by the implosion phase of a fast Z-pinch discharge in a gas-filled capillary," Opt. Lett. 25, 10-12 (2000)