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Laser-driven proton scaling laws and new paths towards energy increase


The past few years have seen remarkable progress in the development of laser-based particle accelerators. The ability to produce ultrabright beams of multi-megaelectronvolt protons routinely has many potential uses from engineering to medicine, but for this potential to be realized substantial improvements in the performances of these devices must be made. Here we show that in the laser-driven accelerator that has been demonstrated experimentally to produce the highest energy protons, scaling laws derived from fluid models and supported by numerical simulations can be used to accurately describe the acceleration of proton beams for a large range of laser and target parameters. This enables us to evaluate the laser parameters needed to produce high-energy and high-quality proton beams of interest for radiography of dense objects or proton therapy of deep-seated tumours.

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Figure 1: Thinner solid targets improve the maximum energy of laser-accelerated protons as well as the laser–proton energy conversion efficiency.
Figure 2: The laser-accelerated proton maximum energy and conversion efficiency increase with laser pulse energy.
Figure 3: Longer pulses improve the laser-accelerated proton maximum as well as the energy conversion efficiency.
Figure 4: Comparison between fluid-model predictions and previously published data.
Figure 5: Study of the evolution of the electron and proton populations during ion acceleration using PIC and fluid simulations.
Figure 6: Projections of required laser energy and intensity to achieve a certain proton maximum energy using the adjusted fluid model.


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We acknowledge the expert support of the LULI and Atlas laser teams and useful discussion with T. Cowan, A. Kemp and Y. Sentoku. This work was supported by DAAD, grant E1127 from Région Ile-de-France, the EU programme HPRI CT 1999-0052, and UNR grant DE-FC08-01NV14050.

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Correspondence to J. Fuchs.

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Fuchs, J., Antici, P., d’Humières, E. et al. Laser-driven proton scaling laws and new paths towards energy increase. Nature Phys 2, 48–54 (2006).

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