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Proceedings Paper

Generation of MeV proton with 30 mJ laser energy by optimizing focusing spot using deformable mirror
Author(s): Takuya Nayuki; Takashi Fujii; Yuji Oishi; Kei Takano; Xiaofang Wang; Alexander A. Andreev; Koshichi Nemoto; Ken-ichi Ueda
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Paper Abstract

The generation of energetic protons using a polyimide tape of 7.5 μm thickness was carried out with laser pulses of 30 mJ energy and 80 fs duration. A deformable mirror system with a genetic algorithm (GA) was developed to optimize the laser-focusing spot. The fitness values used in the GA were measured from the focusing intensities under the low-gain condition of the power amplifier, or from x-ray in situ signals emitted from the target. Although we obtained a diffraction-limited size of 2 μm (full width at half maximum) using the former value, a precise optimization using the latter value was essential to accelerate protons whose flux was 106/MeV/shot to a maximum energy of 1.1±0.3 MeV with laser pulses of only 30 mJ energy since a laser spot that is too tight may be sensitive to wave-front distortion caused by residual thermal lenses of the power amplifier.

Paper Details

Date Published: 8 June 2006
PDF: 6 pages
Proc. SPIE 6018, 5th International Workshop on Adaptive Optics for Industry and Medicine, 60180F (8 June 2006); doi: 10.1117/12.669278
Show Author Affiliations
Takuya Nayuki, Central Research Institute of Electric Power Industry (Japan)
Takashi Fujii, Central Research Institute of Electric Power Industry (Japan)
Yuji Oishi, Central Research Institute of Electric Power Industry (Japan)
Kei Takano, Central Research Institute of Electric Power Industry (Japan)
Xiaofang Wang, Central Research Institute of Electric Power Industry (Japan)
Alexander A. Andreev, Central Research Institute of Electric Power Industry (Japan)
Koshichi Nemoto, Central Research Institute of Electric Power Industry (Japan)
Ken-ichi Ueda, Univ. of Electro Communications (Japan)


Published in SPIE Proceedings Vol. 6018:
5th International Workshop on Adaptive Optics for Industry and Medicine

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