Spectral shaping of laser generated proton beams

Pfotenhauer, S.M. and Jäckel, O. and Sachtleben, A. and Polz, J. and Ziegler, W. and Schlenvoigt, H.P. and Amthor, K.U. and Kaluza, M. C. and Ledingham, K.W.D. and Sauerbrey, R. and Gibbon, P. and Robinson, A. P. L. and Schwoerer, H. (2008) Spectral shaping of laser generated proton beams. New Journal of Physics, 10. 033034. ISSN 1367-2630 (https://doi.org/10.1088/1367-2630/10/3/033034)

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Abstract

The rapid progress in the field of laser particle acceleration has stimulated a debate about the promising perspectives of laser based ion beam sources. For a long time, the beams produced exhibited quasi-thermal spectra. Recent proof-of-principle experiments demonstrated that ion beams with narrow energy distribution can be generated from special target geometries. However, the achieved spectra were strongly limited in terms of monochromacity and reproducibility. We show that microstructured targets can be used to reliably produce protons with monoenergetic spectra above 2 MeV with less than 10% energy spread. Detailed investigations of the effects of laser ablation on the target resulted in a significant improvement of the reproducibility. Based on statistical analysis, we derive a scaling law between proton peak position and laser energy, underlining the suitability of this method for future applications. Both the quality of the spectra and the scaling law are well reproduced by numerical simulations.