In the far field of the intensity distribution of the beam delivered by a two-stage transient–collisional excitation X-ray laser(XRL), a non-expected interference pattern that is stable from shot to shot has been dis...In the far field of the intensity distribution of the beam delivered by a two-stage transient–collisional excitation X-ray laser(XRL), a non-expected interference pattern that is stable from shot to shot has been discovered. It is demonstrated that the interference is caused by the emergence of an imaginary source in the amplifying plasma, which is phase matched to the radiation of the generator. The observed phenomenon is called an X-ray coherent mirage. To explain the obtained results, a new theoretical approach is developed. The basic essential conditions for formation of the X-ray mirage are formulated, and possible applications are discussed. This paper details the experiments, including the formulation of the necessary and sufficient conditions for formation of the X-ray mirage, and possible applications are discussed.展开更多
We report on the design and characterization of the plasma mirror system installed on the J-KAREN-P laser at the Kansai Photon Science Institute,National Institutes for Quantum Science and Technology.The reflectivity ...We report on the design and characterization of the plasma mirror system installed on the J-KAREN-P laser at the Kansai Photon Science Institute,National Institutes for Quantum Science and Technology.The reflectivity of the single plasma mirror system exceeded 80%.In addition,the temporal contrast was improved by two orders of magnitude at 1 ps before the main pulse.Furthermore,the laser near-field spatial distribution after the plasma mirror was kept constant at plasma mirror fluence of less than 100 kJ/cm^(2).We also present the results of investigating the difference and the fluctuation in energy,pulse width and pointing stability with and without the plasma mirror system.展开更多
We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility.We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stret...We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility.We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stretched pulse and the post-pulse in a chirped-pulse amplification system.We have shown that the time at which the pre-pulse is generated by the post-pulse and its shape are related to the time difference between the stretched main pulse and the post-pulse.With this investigation,we have found and identified the origins of the pre-pulses and have demonstrated the removal of most pre-pulses by eliminating the post-pulse with wedged optics.We have also demonstrated the impact of stretcher optics on the picosecond pedestal.We have realized orders of magnitude enhancement of the pedestal by improving the optical quality of a key component in the stretcher.展开更多
In 2017 the journal High Power Laser Science and Engineering produced a Special Issue on Target Fabrication.The scope of the special issue was to span the latest developments and reviews on topics related to their dep...In 2017 the journal High Power Laser Science and Engineering produced a Special Issue on Target Fabrication.The scope of the special issue was to span the latest developments and reviews on topics related to their deployment on ultrahigh-energy/power laser facilities.The topics invited for inclusion were:·Target assembly·Novel characterization展开更多
基金partly supported by RFBR-JSPS collaboration program (RFBR Grant 14-02-92107)
文摘In the far field of the intensity distribution of the beam delivered by a two-stage transient–collisional excitation X-ray laser(XRL), a non-expected interference pattern that is stable from shot to shot has been discovered. It is demonstrated that the interference is caused by the emergence of an imaginary source in the amplifying plasma, which is phase matched to the radiation of the generator. The observed phenomenon is called an X-ray coherent mirage. To explain the obtained results, a new theoretical approach is developed. The basic essential conditions for formation of the X-ray mirage are formulated, and possible applications are discussed. This paper details the experiments, including the formulation of the necessary and sufficient conditions for formation of the X-ray mirage, and possible applications are discussed.
文摘We report on the design and characterization of the plasma mirror system installed on the J-KAREN-P laser at the Kansai Photon Science Institute,National Institutes for Quantum Science and Technology.The reflectivity of the single plasma mirror system exceeded 80%.In addition,the temporal contrast was improved by two orders of magnitude at 1 ps before the main pulse.Furthermore,the laser near-field spatial distribution after the plasma mirror was kept constant at plasma mirror fluence of less than 100 kJ/cm^(2).We also present the results of investigating the difference and the fluctuation in energy,pulse width and pointing stability with and without the plasma mirror system.
基金supported by JSPS KAKENHI Grant Number JP20H01882。
文摘We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility.We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stretched pulse and the post-pulse in a chirped-pulse amplification system.We have shown that the time at which the pre-pulse is generated by the post-pulse and its shape are related to the time difference between the stretched main pulse and the post-pulse.With this investigation,we have found and identified the origins of the pre-pulses and have demonstrated the removal of most pre-pulses by eliminating the post-pulse with wedged optics.We have also demonstrated the impact of stretcher optics on the picosecond pedestal.We have realized orders of magnitude enhancement of the pedestal by improving the optical quality of a key component in the stretcher.
文摘In 2017 the journal High Power Laser Science and Engineering produced a Special Issue on Target Fabrication.The scope of the special issue was to span the latest developments and reviews on topics related to their deployment on ultrahigh-energy/power laser facilities.The topics invited for inclusion were:·Target assembly·Novel characterization
