400 TW operation of Orion at ultra-high contrast. (15th August 2018)

• Record Type: Journal Article
• Authors: 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
• Is Part Of: High power laser science and engineering. Volume 6(2018)
• Publication Date: 2018-08-15
• Subjects: contrast, -- frequency conversion, -- ultra-high intensity; High power lasers -- Periodicals; 621.366
• DOI: 10.1017/hpl.2018.44
• Languages: English
• ISSNs: 2095-4719

Abstract

Abstract : The Orion facility at the Atomic Weapons Establishment in the United Kingdom 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 crystals. Since the beam diameter of the compressed pulse is ${\sim}600$ 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 $\times$ 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.