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Significant Increase in the Number of Energetic Protons with Two Hot Temperatures of 1 and 4 MeV During the Interaction of an Ultra-Intense Laser with a Foam Target Near the Critical Density and Coulomb piston signature.
G. Malka,1 P. Raczka,2 H. Larreur,1,3,4 D. Molloy,4,5 Y. Fukuda,6 K. Batani,2 D. Singappuli,1 Bing Liu,7 Dong Ao,7 Wei Kang,8 S. Pikuz,3 A. Martynenko,9 N. Borisneko,10 T. Pikuz,11 W.Nazarov,12 G.Giuntelli,5 T. Hayakawa,5 A. Yogo,6 Z. Lan,6 Y. Arikawa,6 A. Morace7, D.Mancelli, 1,14,15 A. Aliverdiev,13 D. Batani,1
1) Université de Bordeaux, CNRS, CEA, CELIA, Unité Mixte de Recherche 5107, Talence 33400, France
2) Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warszawa, Poland
3) Departamento de Física Fundamental, Universidad de Salamanca, 37008 Salamanca, Spain
4) HB11 Energy Holdings Pty, Freshwater 2096, Australia
5) Centre for Light-Matter Interactions, Queen’s University, Belfast, Belfast BT7 1NN, United Kingdom
6) Institute of Laser Engineering, Osaka University, 2-6, Yamadaoka, Suita, Osaka, Japan
7) ENN Fusion Technology R&D Center (ENN-FTRC), Langfang, China
8) HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871, China
9) Plasma Physics Department, GSI Helmholtzzentrum fur Schwerionenforschung, 64291 Darmstadt, Germany
10) Lebedev, Russia
11) Institute for Laser Technology, 2-6, Yamadaoka, Suita, Osaka, Japan
12) Wigen Nazarov
13) IGRRE JIHT RAS, Makhachkala, Russia
14) Institute of Plasma Physics and Lasers-IPPL, University Research and Innovation Centre, Hellenic Mediterranean University, 74100 Rethymno, Greece
15) Department of Electronic Engineering, Hellenic Mediterranean University, 73133 Chania, Greece
Key words: proton acceleration, high intensity lasers, low density foams, TNSA
ABSTRACT
We present the experimental results of proton acceleration obtained at the LFEX laser facility in Osaka, 1 kJ, 1 ps, I > 10¹⁹ W/cm², with foam targets of 3, 8, and 16 mg/cc and 200 m thick, as well as with thin foil targets. For the 3 mg/cc foams, the proton distribution, emitted on the back side of the target, exhibits two hot temperatures: one of 1 MeV for energies below 8 MeV, and one of 4,5 MeV for energies up to 20 MeV. The novel result is that the number of protons increases by more than a decade, and significantly increasing the conversion efficiency from laser energy to the proton beam. By increasing the angle of incidence of the laser beam on the target from 0 to 15°, we observe that the proton beam remains perpendicular to the back face of the target. We discuss the competition between the different acceleration processes involved, such as TNSA and RPA. In the case of thin foil (6 m CH), the formation of energy bunches in the proton spectra which are due to the interplay between the protons and the highly charged carbon ions (mostly C6+) which are also accelerated by the lasers. These finding are coherent with theoretical formulation predictions that the carbon ions act as a “Coulomb piston” on protons.
| Working group | WG2 |
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