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Peak intensities of 1019 W cm' have been reliably obtained from a high power Nd :glass laser using chirped pulse amplification. An Additive Pulse Modelocked oscillator incorporating diode pumped Nd : LMA was used to generate the sub-picosecond pulse. The focal spot intensity distribution has been characterized in detail showing a three times diffraction limited beam.

The process of Chirped Pulse Amplification (CPA) [1] as presently implemented on the VULCAN glass laser is capable of delivering 30 J to target with pulselengths in the sub-picosecond regime [2][3]. Results from various experiments [4][5] haveshown that intensities of 1018 1019 W cm2 have been achieved on target enabling users to carry out important new experiments in X-ray laser research, laser fusion, basic plasma physics and particle acceleration. An EPSRC (Engineering and Physical Sciences Research Council) facility upgrade grant has been awarded to increase the current operational level of 35 TW, to over 200 TW. This upgrade forms Phase I of a two phase upgrade to raise the performance of VULCAN to the PetaWatt level. This paper details the design of the upgraded system and describes a new interaction chamber which takes full advantage of the availability of synchronous kJ multi-beam long pulse operation on VULCAN with the CPA capabilities.A precursor to the upgrade was a full characterisation of the systems current CPA performance. Measurements of the transmitted energy through pinholes of various diameters placed in the focal plane were used to characterise the intensity distribution. Images from an Equivalent Plane Monitor (EPM) were taken simultaneously with the pinhole transmission measurements and good agreement between the data sets was obtained. The effect of B-integral [6] on the focusability of the beam was also studied and the beam uniformity was examined.

VULCAN is a multi-beam, multi-terawatt laser facility based on Nd:glass operating at 1053 nm. The system is highly versatile, supplying four experimental areas with laser radiation at a range of pulse durations from 700 fs to 20 ns, at fundamental frequency, frequency doubled, or, as a limited option, frequency tripled wavelengths. Beams are available in a number of geometries dictated by the university based programmes, which at present include: cluster; line focus including Xray laser oscillator I amplifier geomeiry; backlighting; probing; and chirped pulse amplification' (CPA) configurations. The system has eight beams which can deliver synchronised long and short pulses including two beams which can deliver subpicosecond CPA pulses. The CPA capabilities on VULCAN2 are an integral part of the laser system, not only delivering sub-picosecond pulses, but allowing uncompressed pulses and multi-pulses to be delivered to the target areas synchronised with the nanosecond pulses. This paper describes the system configuration, details the means of pulse synchronisation and presents some of the pulse manipulation techniques used on VULCAN to provide the laser requirements for the experimental programme.

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