38 research outputs found
Recommended from our members
Scaling to Ultra-High Intensities by High-Energy Petawatt Beam Combining
The output pulse energy from a single-aperture high-energy laser amplifier (e.g. fusion lasers such as NIF and LMJ) are critically limited by a number of factors including optical damage, which places an upper bound on the operating fluence; parasitic gain, which limits together with manufacturing costs the maximum aperture size to {approx} 40-cm; and non-linear phase effects which limits the peak intensity. For 20-ns narrow band pulses down to transform-limited sub-picosecond pulses, these limiters combine to yield 10-kJ to 1-kJ maximum pulse energies with up to petawatt peak power. For example, the Advanced Radiographic Capability (ARC) project at NIF is designed to provide kilo-Joule pulses from 0.75-ps to 50-ps, with peak focused intensity above 10{sup 19} W/cm{sup 2}. Using such a high-energy petawatt (HEPW) beamline as a modular unit, they discuss large-scale architectures for coherently combining multiple HEPW pulses from independent apertures, called CAPE (Coherent Addition of Pulses for Energy), to significantly increase the peak achievable focused intensity. Importantly, the maximum intensity achievable with CAPE increases non-linearly. Clearly, the total integrated energy grows linearly with the number of apertures N used. However, as CAPE combines beams in the focal plane by increasing the angular convergence to focus (i.e. the f-number decreases), the foal spot diameter scales inversely with N. Hence the peak intensity scales as N{sup 2}. Using design estimates for the focal spot size and output pulse energy (limited by damage fluence on the final compressor gratings) versus compressed pulse duration in the ARC system, Figure 2 shows the scaled focal spot intensity and total energy for various CAPE configurations from 1,2,4, ..., up to 192 total beams. They see from the fixture that the peak intensity for event modest 8 to 16 beam combinations reaches the 10{sup 21} to 10{sup 22} W/cm{sup 2} regime. With greater number of apertures, or with improvements to the focusability of the individual beams, the maximum peak intensity can be increased further to {approx} 10{sup 24} W/cm{sup 2}. Lastly, an important feature of the CAPE architecture is the ability to coherently combine beams to produce complex spatio-temporal intensity distributions for laser-based accelerators (e.g. all-optical electron injection and acceleration) and high energy density science applications such as fast ignition
Recommended from our members
Development of diagnostics for high-energy petawatt pulses
Applications accessed by high energy petawatt (HEPW) lasers require complete, single-shot characterization of pulse spatial, temporal, and energy characteristics. We describe techniques that enable single-shot characterization of the temporal shape and pulse contrast of HEPW pulses with >10{sup 8} dynamic range over a ns-temporal window. Approaches to measure pulse durations that span two orders of magnitude will be discussed. Finally, we describe a novel implementation of spectrally dispersed two-beam interferometry for measurement of the phase difference between two HEPW pulses. This technique can be applied to dispersion and B-integral measurements in a HEPW system, as well as to achieve precise timing of nanosecond pulses. Lastly, spectrally dispersed interferometry represents an ideal technique to enable coherent addition of HEPW pulses for production of ultrahigh intensities
Recommended from our members
10-kJ Status and 100-kJ Future for NIF PetaWatt Technology
We discuss the status of the NIF ARC, an 8-beam 10-kJ class high-energy petawatt laser, and the future upgrade path of this and similar systems to 100-kJ-class with coherent phasing of multiple apertures
Recommended from our members
Continuous contour phase plates for tailoring the focal plane irradiance profile
We present fully continuous phase screens for producing super-Gaussian focal-plane irradiance profiles. Such phase screens are constructed with the assumption of either circular symmetric near-field and far-field profiles or a separable phase screen in Cartesian co-ordinates. In each case, the phase screen is only a few waves deep. Under illumination by coherent light, such phase screens produce high order super-Gaussian profiles in the focal plane with high energy content effects of beam aberrations on the focal profiles and their energy content are also discussed