量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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We report on experimental investigations of proton acceleration from solid foils irradiated with
PW-class laser-pulses, where highest proton cut-off energies were achieved for temporal pulse
parameters that varied significantly from those of an ideally Fourier transform limited (FTL) pulse.
Controlled spectral phase modulation of the driver laser by means of an acousto-optic programmable
dispersive filter enabled us to manipulate the temporal shape of the last picoseconds around the
main pulse and to study the effect on proton acceleration from thin foil targets. The results show that
applying positive third order dispersion values to short pulses is favourable for proton acceleration
and can lead to maximum energies of 70 MeV in target normal direction at 18 J laser energy for thin
plastic foils, significantly enhancing the maximum energy compared to ideally compressed FTL pulses.
The paper further proves the robustness and applicability of this enhancement effect for the use of
different target materials and thicknesses as well as laser energy and temporal intensity contrast
settings. We demonstrate that application relevant proton beam quality was reliably achieved
over many months of operation with appropriate control of spectral phase and temporal contrast
conditions using a state-of-the-art high-repetition rate PW laser system.
Proton beam quality enhancement by spectral phase control of a PW‑class laser system
