Enhancement of ion generation in femtosecond ultraintense laser-foil interactions by defocusing

Journal Article · Mon Feb 20 00:00:00 EST 2012 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.3688027· OSTI ID:22025447

Xu, M H ^[1]; Li, Y T; Liu, F ^[2]; Carroll, D C; McKenna, P ^[3]; Foster, P S; Hawkes, S; Streeter, M J. V.; Spindloe, C; Neely, D ^[4]; Kar, S; Markey, K; Zepf, M ^[5]; Sheng, Z M; Zhang, J ^[2]; Wahlstroem, C -G ^[6]; Zheng, J ^[7]

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1. Department of Physics, China University of Mining and Technology (Beijing), Beijing 100083 China (China)
2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)
3. Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)
4. Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX (United Kingdom)
5. Centre for Plasma Physics, Queen's University Belfast, BT7 1NN (United Kingdom)
6. Department of Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)
7. Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

A simple method to enhance ion generation with femtosecond ultraintense lasers is demonstrated experimentally by defocusing laser beams on target surface. When the laser is optimally defocused, we find that the population of medium and low energy protons from ultra-thin foils is increased significantly while the proton cutoff energy is almost unchanged. In this way, the total proton yield can be enhanced by more than 1 order, even though the peak laser intensity drops. The depression of the amplified spontaneous emission (ASE) effect and the population increase of moderate-energy electrons are believed to be the main reasons for the effective enhancement.

• OSTI ID: 22025447
• Journal Information: Applied Physics Letters, Vol. 100, Issue 8; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ELECTRON EMISSION
ELECTRONS
FOILS
ION EMISSION
LASER TARGETS
LASER-PRODUCED PLASMA
PLASMA PRODUCTION
PROTONS
SUPERRADIANCE