400TW Operation of Orion at Ultra-high Contrast [Early Posting]
The Orion facility at AWE in the UK has the capability to operate one of its two 500 J, 500 fs short pulse petawatt beams at the second harmonic, the principal reason being to increase the temporal contrast of the pulse on target. This is achieved post-compression, using 3 mm-thick type 1 potassium dihydrogen phosphate (KDP) crystals. Since the beam diameter of the compressed pulse is ~600 mm, it is impractical to achieve this over the full aperture due to the unavailability of the large aperture crystals. Frequency doubling was originally achieved on Orion using a circular sub-aperture of 300 mm diameter. The reduction in aperture limited the output energy to 100 J. The second harmonic capability has been upgraded by taking two square 300 mm x 300 mm sub-apertures from the beam and combining them at focus using a single paraboloidal mirror, thus creating a 200 J, 500 fs, i.e. 400 TW facility at the second harmonic.
Parker Stefan,Danson Colin,Egan David,Elsmere Stephen,Girling Mark,Harvey Ewan,Hillier David,Hussey Dianne,Masoero Stephen,McLoughlin James,Penman Rory,Treadwell Paul,Winter David,Hopps Nicholas. 400TW Operation of Orion at Ultra-high Contrast[J].High Power Laser Science and Engineering,,():.