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To reduce the acidity defect of 4,8-dihydrodifurazano[3,4-b,e]pyrazine(DFP), a new energetic ionic compound aminourea salt of 4,8-dihydrodifurazano[3,4-b,e]pyrazine (DSDFP) was designed and synthesized with a yield of 72.6%. The structure of target compound was characterized by means of NMR (1H and 13C), IR spectra, elemental analysis and single crystal X-ray diffraction. The thermal stability was tested by DSC and TG method and DSDFP shows good thermal stability with exothermic decomposition peaks in the range of 267.3 °C ∼ 282.3 °C. The impact sensitivity was measured using BAM standard method and the detonation performance was computed by Kamlet-Jacobs equations. Results show that DSDFP exhibits excellent impact sensitivity of greater than 40 J and desirable detonation performance with detonation velocity of 7891 m/s and detonation pressure of 27.1 GPa. These results highlight its great promise of potential candidates for high-performance energetic salt.

Focal spot effects on the generation of proton beams are investigated by a high-intensity high-contrast laser irradiating on solid foil in target normal sheath acceleration experiments. Different spot size, transverse shape, and intensity of the laser are obtained by appropriately using deformable mirrors and parabolic mirrors. Experiments show that the maximum proton energy is mainly determined by the laser intensity if the focal spot size is not seriously changed. Compared with the previous experimental results, the optimum foil thickness d o is scaled by the laser intensity I as d o ~ I 0.33. The corresponding theoretical estimation is carried out as d o ~ I 0.25 for ultra-high intensity laser systems with similar contrast. MULTI and particle-in-cell simulations are used to interpret the experimental results.

Significant enhancement of temporal contrast is achieved in a femtosecond petawatt Ti:sapphire laser. A pulse cleaning technique, combining double-CPA, non-collinear optical parametrical amplification and second harmonics generation, is applied to improve the amplified spontaneous emission (ASE) contrast. Meanwhile, pre-pulse leaking from the regenerative amplifier is suppressed by double Pockels cells and a saturable absorber. Measurement results show that pre-pulse on nanosecond scale can be effectively suppressed and the ASE contrast can be improved from the original ~10−8 to ~2 × 10−12. Proton acceleration experimental results with a foil target also demonstrate a significant enhancement of temporal contrast.

We demonstrate a carrier-envelope phase (CEP) stabilized high temporal contrast generator at 1053 nm for the first time. The device relies on a collinear optical parametric amplifier (OPA) followed by a frequency-doubling crystal. It is driven by a femtosecond laser source centered at 800 nm and finally generates CEP passively stabilized pulses with an energy of 130 μJ and a FWHM for the spectrum of 40 nm with 46 fs pulse duration at 1053 nm. The temporal contrast reaches >1011 at a few picoseconds before the main pulse.

Theoretical and experimental investigations are carried out to determine the influence of the time delay between the input seed pulse and pump pulses on transverse parasitic lasing in a Ti:sapphire amplifier with a diameter of 80?mm, which is clad by a refractive index-matched liquid doped with an absorber. When the time delay is optimized, a maximum output energy of 50.8?J is achieved at a pump energy of 105?J, which corresponds to a conversion efficiency of 47.5%. Based on the existing compressor, the laser system achieves a peak power of 1.26?PW with a 29.0?fs pulse duration.