Orion facility status update

Abstract

ABSTRACT The Orion laser facility at AWE in the UK began operations at the start of 2012 to study high energy density physics. It consists of ten nanosecond beam lines and two sub-picosecond beam lines. Th e nanosecond beam lines each deliver 500 J per beam in 1ns at 351nm with a user -definable pulse shape between 0.1ns an d 5ns. The short pulse beams each deliver 500J on target in 500fs with an intensity of greater than 10 21 Wcm -2 per beam. All beam lines have been demonstrated, delivering a pulse to target as described. A summary of the design of the facility will be presented, along with its operating performa nce over the first year of experimental campaigns. The facility has the capability to frequency-double one of the short pulse beams, at sub aperture, to deliver a high contrast short pulse to target with up to 100J. This occurs post-compression and uses a 3mm thick, 300mm aperture KDP crystal. The design and operational perfor mance of this work will be presented. During 2012, the laser performance requirements have been demonstrated and key diagnostics commissioned; progress of this will be presented. Target diagnostics have also been commissioned during this period. Also, there is a development program under way to improve the contrast of the short pulse (at the fundamental) and the operational efficiency of the long pulse. It is intended that, from March 2013, 15 % of facility operating time will be made available to external academic users in addition to collaborative experiments with AWE scientists. Keywords: High power lasers, Nd:glass lasers, OPCPA, high energy density physics 1. INTRODUCTION The Orion laser facility’s construction was completed in 2011 at AWE in the UK. All beam lines have now been commissioned, with all twelve fired to target and the first e xperimental campaigns undertaken. Orion, which is used for high energy density plasma physics experiments, consists of ten ‘long pulse’ beams, and two ‘short pulse’ beams, with the following baseline performance: the long pulse beams each deliver 500J at 351nm in a user-variable pulse length from 100ps to 5ns; the short pulse beams each deliver 500J centered around 1054nm with a pulse length adjustable between 0.5ps and 20ps. The Facility layout can be seen in Figure 1, the main beam lines are all built on either side of two large space frame structures housed on the first floor of the building. The long pulse beams co nsist of two stacks of five beam lines; each stack is seeded with a Pre-Amplifier Module (PAM) [1]. The PAM’s are seeded via fiber, from a rack mounted pulse generation system housed on the lower floor of the building known as Optical Pulse Generation 1 (OPG1). The PAM’s amplify, spatially shape the pulse and offer the ability to im part two dimensional smoothing by spectral dispersion (2D-SSD). The long pulse beam architecture comprises an angular multiplexed four pass system, with separation and redirection near the pinhole plane of a long spatial filter. Each beam line has four 200mm aperture disk amplifiers (LG770 Nd:phosphate glass). The pulse is then frequency tripled in the target hall, before delivery to target via five