<title>Focusing system of multiterawatt laser facility (PROGRESS-P)</title>

Abstract

Focusing of multiterawatt laser beams is of particular importance for superstrong field experiments. The parameters of focusing system of 30-TW Nd:glass laser facility PROGRESS-P with chirped pulse amplification and results of experimental investigations oflaser beam propagation through this system are presented. Near diffraction-limited beam quality is obtained at output laser amplifier chain by use the low-thermal phosphate Nd:glass and high quality optical elements. Output 180 mm beam is compressed to 1.5 ps using two holographic gratings with dimensions 420x210 mm, injected in target chamber through the LiF-window with low nonlinear refractive index coefficient and focused to targets by means developed fYi . 1 onaxis parabolic mirror with focal length of 200 mm. Over 50% energy is obtained in 6-7 pm focal spot in target chamber for low power beam. Determination ofthe focal spot dimensions for 10 TW beam from X-ray plasma image show that microspot diameter not exceeds 7 .tm.