There has been considerable interest in the last 10 years in the physics of ultra-high power laser interactions. With all high power lasers such as Vulcan there is a limit to the energy that can be extracted from laser amplifiers at short pulse-lengths due to the intensity dependent non-linear refractive index. The technique of Chirped Pulse Amplification has overcome the classic limit and has resulted in massive increases in focused intensity. The large increase in on target intensity is achieved by a substantial, usually orders of magnitude, reduction in pulse duration while at the same time maintaining comparable pulse energy and focusability.

The main requirements for a fast igniter laser beam are reviewed and shown to favour short wavelength and ultrahigh brightness. These requirements are met by the new KrF laser system at Rutherford Appleton Laboratory called TITANIA. TITANIA uses two schemes to enhance the laser beam brightness. The first is chirped pulse amplification which is used to enhance brightness by compressing the pulse into the femtosecond region. In this mode TITANIA produces in the region of 250 mJ on target in 700 fs. The second mode of operation uses a Raman technique for beam combining and beam clean-up which is designed to give a single beam of 80 joules on target in a pulselength of 60 ps. In this scheme the KrF wavelength is Raman shifted to 268 nm. The Raman amplifiers will use gaseous rather than solid windows and experiments which demonstrate their feasibility will be described. A concept for a reactor scale fast igniter beam using the Raman technique will be discussed.

The process of Chirped Pulse Amplification (CPA) as presently implemented on the VULCAN glass laser is capable of delivering 30 J to target with pulselengths in the sub- picosecond regime. Results from various experiments have shown that intensities of 1018 - 1019 W cm-2 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.

An injector-amplifier architecture for XUV lasers has been developed and demonstrated using the Ge XXIII collisional laser. Results are described for injection into single and double plasma amplifiers. Prismatic lens-like and higher order aberrations in the amplifier are considered. Limitations on ultimate brightness are discussed and also scaling to operation at shorter wavelengths. A preliminary study has been made of UV multiphoton ionization using 300 fs pulses at high intensity.

The class of XUV laser operating by collisional excitation and driven by typically kilojoule nanosecond laser pulses is well developed, and current research aims to produce more coherent beams and beam characteristics tailored to specific applications.

Chirped pulse amplification (CPA) and recompression have been used in a large aperture KrF laser system. The power focused onto target in a 300 fs pulse reached 1 TW with an irradiance of ≈ 1019 W/cm2.

The development of ultrabright lasers is progressing rapidly particularly in the direction of table-top-terawatt systems operating at high pulse repetition rate with relatively low pulse energy. The highest pulse energies and highest absolute powers are being generated by the adaptation of larger-scale high energy laser systems operating in single pulse mode. The maximum focused intensity from either type of laser is determined by the beam brightness B which can be expressed in units of Watts cm-2 sterad-1. The focused intensity is then approximately B/f2 where f is the focal length to diameter ratio of the focusing optic. Brightness can be expressed as B = PS/λ2 where P is the power, λ the wavelength and S the Strehl ratio, quantifying the ratio of brightness in a beam with less than diffraction limited quality to that in a diffraction limited beam.

A time resolving XUV spectrograph has been developed for x-ray laser research. A grazing incidence flat field grating is coupled to a soft x-ray streak camera to provide high temporal resolution over a large spectral range. Wavelengths between 50 Å and 400 A are focused onto a flat field, allowing detectors to be easily coupled to the spectrograph. Time resolved spectra covering any ''100 A window within flat field can be recorded using a streak camera. The spectrograph and detector were absolutely calibrated in the XUV spectral region using synchrotron radiation. The instrument and its characterization will be described. The wavelength range of the spectrograph has been extended to approximately 11 R through the use of a higher periodicity flat field grating. Preliminary spectroscopic results will be presented.

A chamber dedicated for use as a laser-produced plasma soft X-ray source is being commissioned at the Central Laser Facility, RAL. The laser used to drive the source is the Nd-glass Vulcan laser [1]. By splitting off the beam at an early stage of amplification, enough power is obtained for a useful soft X-ray source and a repetition rate of a shot every 2 minutes is possible, without interfering with the other users of the laser. By operating in this way, it should be possible to use the chamber in the low duty cycle mode favoured by biologists. The target chamber has provision for X-rays to be relayed vertically down using a grazing incidence mirror, so that exposures will be possible outside of the vacuum with horizontally placed recording medium.

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This paper reports the design and characterization of the newly upgraded Nd:glass laser facility at the Rutherford Laboratory. Emphasis is placed on the unusual aspects consequent on its role as a multiuser facility, where reliability and flexibility are of paramount importance. The basic facility configuration is of two high-power laser systems in parallel-a six-beam laser for implosion experiments and a separate high-power single beamline for either X-ray backlighting diagnostics of implosion experiments or use in a separate single-beam target area. Additional flexibility is provided by remotely controlled changeover mirrors enabling groups of amplifiers to be used in different combinations for various energies and shot repetition rates. Either a mode-locked or aQ-switched oscillator can be selected to provide a range of pulse durations from 50 ps to many nanoseconds. Harmonic generation is used routinely to give a choice of wavelengths for different experiments. The six-beam system is normally run at the second harmonic, although the fundamental wavelength is also available, while the single-beam target area can use fundamental, second, or third harmonics.

A 20 1 hydrogen filled track sensitive target has been successfully operated in the 1.5 m cryogenic bubble chamber at The Rutherford High Energy Laboratory. The chamber was filled with a mixture of neon and hydrogen at a concentration of 45 mol % neon giving a radiation length of 860 mm. Satisfactory track quality in both target and chamber was achieved and 65 000 pictures have been obtained in a 4 GeV/c π+ beam.