• High Power Laser Science and Engineering
  • Vol. 4, Issue 1, 010000e6 (2016)
Xin Zhang, Wei Zhou, Wanjun Dai, Dongxia Hu, Xuewei Deng, Wanqing Huang, Lidan Zhou, Qiang Yuan, Xiaoxia Huang, De’en Wang, and Ying Yang
Author Affiliations
  • Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
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    Abstract

    Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patterns and the optics damage spot distributions from the surface phase defects. Origins are discussed during the processes of optics manufacturing and diagnostics, revealing potential improvements for future optics manufacturing techniques and diagnostic index, which is meaningful for fusion level laser facility construction and its operation safety.

    1 Introduction

    In order to achieve fusion ignition through inertial confinement[1], high-power laser facilities are built to provide enough laser energy and power to compress the fusion fuels in the target pellet, such as the national ignition facility (NIF) in the United States[2], the Laser Megajoule in France[3], and the SG series laser facilities in China[4]. Such laser facilities designed for fusion ignition always produce more than 15 kJ fundamental laser energy in one single beam, which is then tripled to ultraviolet with 10 kJ laser energy, producing about 12 and $8~\text{J}/\text{cm}^{2}$ laser fluence in fundamental and ultraviolet sections separately. These relatively high laser fluences impose huge pressures on the optics’ resistance to damage, especially in the ultraviolet section[5]. In order to overcome such damage threats, technical methods and operation strategies have been developed. On the one hand, the qualities of the optics in ultraviolet section must be improved to suppress the damage initials. For example, NIF spent more than 10 years improving the qualities of the optics and has developed a complicated strategy to circulate the damaged optics[6] in spite of it being costly and inefficient. On the other hand, the beam quality of the fundamental lasers need to be improved to get rid of the optics damage from small-scale intensity modulation, such as the image-relay designs in high-power laser facilities and the improvement of the surface quality of the large-scale optics[7].

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    Xin Zhang, Wei Zhou, Wanjun Dai, Dongxia Hu, Xuewei Deng, Wanqing Huang, Lidan Zhou, Qiang Yuan, Xiaoxia Huang, De’en Wang, Ying Yang. Surface phase defects induced downstream laser intensity modulation in high-power laser facility[J]. High Power Laser Science and Engineering, 2016, 4(1): 010000e6
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    Received: Nov. 7, 2015
    Accepted: Jan. 9, 2016
    Published Online: Oct. 25, 2016
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