Ring-like spatial distribution of laser accelerated protons in the ultra-high-contrast TNSA-regime

Becker, G. A.; Tietze, S.; Keppler, S.; Reisloehner, J.; Bin, J. H.; Bock, L.; Brack, F-E; Hein, J.; Hellwing, M.; Hilz, P.; Hornung, M.; Kessler, A.; Kraft, S. D.; Kuschel, S.; Liebetrau, H.; Ma, W.; Polz, J.; Schlenvoigt, H-P; Schorcht, F.; Schwab, M. B.; Seidel, A.; Zeil, K.; Schramm, U.; Zepf, M.; Schreiber, J.; Rykovanov, S. und Kaluza, M. C. (2018): Ring-like spatial distribution of laser accelerated protons in the ultra-high-contrast TNSA-regime. In: Plasma Physics and Controlled Fusion, Bd. 60, Nr. 5, 55010

Abstract

The spatial distribution of protons accelerated from submicron-thick plastic foil targets using multi-terawatt, frequency-doubled laser pulses with ultra-high temporal contrast has been investigated experimentally. A very stable, ring-like beam profile of the accelerated protons, oriented around the target's normal direction has been observed. The ring's opening angle has been found to decrease with increasing foil thicknesses. Two-dimensional particle-in-cell simulations reproduce our results indicating that the ring is formed during the expansion of the proton density distribution into the vacuum as described by the mechanism of target-normal sheath acceleration. Here-in addition to the longitudinal electric fields responsible for the forward acceleration of the protons-a lateral charge separation leads to transverse field components accelerating the protons in the lateral direction.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0741-3335
• Sprache: Englisch