scholarly journals Recent Advances in Laser-Induced Surface Damage of KH2PO4 Crystal

2020 ◽  
Vol 10 (19) ◽  
pp. 6642 ◽  
Author(s):  
Mingjun Chen ◽  
Wenyu Ding ◽  
Jian Cheng ◽  
Hao Yang ◽  
Qi Liu
Keyword(s):  
Laser Irradiation ◽  
Inertial Confinement Fusion ◽  
Short Pulse ◽  
Damage Threshold ◽  
Damage Mechanism ◽  
Inertial Confinement ◽  
Pulse Laser Irradiation ◽  
Damage Initiation ◽  
Three Stages ◽  
Laser Induced Damage

As a hard and brittle material, KDP crystal is easily damaged by the irradiation of laser in a laser-driven inertial confinement fusion device due to various factors, which will also affect the quality of subsequent incident laser. Thus, the mechanism of laser-induced damage is essentially helpful for increasing the laser-induced damage threshold and the value of optical crystal elements. The intrinsic damage mechanism of crystal materials under laser irradiation of different pulse duration is reviewed in detail. The process from the initiation to finalization of laser-induced damage has been divided into three stages (i.e., energy deposition, damage initiation, and damage forming) to ensure the understanding of laser-induced damage mechanism. It is clear that defects have a great impact on damage under short-pulse laser irradiation. The burst damage accounts for the majority of whole damage morphology, while the melting pit are more likely to appear under high-fluence laser. The three stages of damage are complementary and the multi-physics coupling technology needs to be fully applied to ensure the intuitive prediction of damage thresholds for various initial forms of KDP crystals. The improved laser-induced damage threshold prediction can provide support for improving the resistance of materials to various types of laser-induced damage.

scholarly journals Target alignment in the Shen-Guang II Upgrade laser facility

2018 ◽  
Vol 6 ◽  
Author(s):  
Lei Ren ◽  
Ping Shao ◽  
Dongfeng Zhao ◽  
Yang Zhou ◽  
Zhijian Cai ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Short Pulse ◽  
Three Dimensional ◽  
Nanosecond Laser ◽  
Alignment Error ◽  
Inertial Confinement ◽  
Pulse Beam ◽  
Rotation Sensor ◽  
Confinement Fusion ◽  
Laser Facility

The Shen-Guang II Upgrade (SG-II-U) laser facility consists of eight high-power nanosecond laser beams and one short-pulse picosecond petawatt laser. It is designed for the study of inertial confinement fusion (ICF), especially for conducting fast ignition (FI) research in China and other basic science experiments. To perform FI successfully with hohlraum targets containing a golden cone, the long-pulse beam and cylindrical hohlraum as well as the short-pulse beam and cone target alignment must satisfy tight specifications (30 and $20~\unicode[STIX]{x03BC}\text{m}$ rms for each case). To explore new ICF ignition targets with six laser entrance holes (LEHs), a rotation sensor was adapted to meet the requirements of a three-dimensional target and correct beam alignment. In this paper, the strategy for aligning the nanosecond beam based on target alignment sensor (TAS) is introduced and improved to meet requirements of the picosecond lasers and the new six LEHs hohlraum targets in the SG-II-U facility. The expected performance of the alignment system is presented, and the alignment error is also discussed.

scholarly journals Surface Contaminant Control Technologies to Improve Laser Damage Resistance of Optics

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaofeng Cheng ◽  
Xinxiang Miao ◽  
Hongbin Wang ◽  
Lang Qin ◽  
Yayun Ye ◽  
...  
Keyword(s):  
High Power ◽  
Inertial Confinement Fusion ◽  
High Energy ◽  
Intense Laser ◽  
Metallic Surface ◽  
Inertial Confinement ◽  
Contamination Control ◽  
Laser Driver ◽  
Laser Facility ◽  
Laser Induced Damage

The large high-power solid lasers, such as the National Ignition Facility (NIF) of America and the Shenguang-III (SG-III) laser facility of China, can output over 2.1 MJ laser pulse for the inertial confinement fusion (ICF) experiments. Because of the enhancement of operating flux and the expansion of laser driver scale, the problem of contamination seriously influences their construction period and operation life. During irradiation by intense laser beams, the contaminants on the metallic surface of beam tubes can be transmitted to the optical surfaces and lead to damage of optical components. For the high-power solid-state laser facilities, contamination control focuses on the slab amplifiers, spatial filters, and final-optical assemblies. In this paper, an effective solution to control contaminations including the whole process of the laser driver is put forward to provide the safe operation of laser facilities, and the detailed technical methods of contamination control such as washing, cleanliness metrology, and cleanliness protecting are also introduced to reduce the probability of laser-induced damage of optics. The experimental results show that the cleanliness level of SG-III laser facility is much better to ensure that the laser facility can safely operate at high energy flux.

scholarly journals Development of high-performance KrF and Raman laser facilities for inertial confinement fusion and other applications

1993 ◽  
Vol 11 (2) ◽  
pp. 331-346 ◽  
Author(s):  
M.J. Shaw ◽  
B. Edwards ◽  
G.J. Hirst ◽  
C.J. Hooker ◽  
M.H. Key ◽  
...  
Keyword(s):  
Power Systems ◽  
Inertial Confinement Fusion ◽  
High Performance ◽  
Short Pulse ◽  
High Reliability ◽  
Laser System ◽  
Raman Laser ◽  
Current Status ◽  
Inertial Confinement ◽  
Laser Amplifiers

This article describes the current status of the KrF development programme based on the Sprite laser system at the Rutherford Appleton Laboratory. High reliability and high shot rate have been demonstrated. Using a unique KrF-pumped Raman laser architecture, beam brightness exceeding 2×1019 Wcm-2 sterad-1 giving a focussed intensity >5 ×1017 Wcm-2 has been achieved. The development of transform-limited short-pulse oscillators is shown to be of importance in avoiding spectral broadening in air propagation of high-intensity beams. Beam smoothing of KrF beams in a multiplexed configuration has been demonstrated for the first time. The technique of echelon-free induced spatial incoherence has been shown to produce smooth intensity distributions in the far field, which remain essentially unchanged on amplification. The development of pulsed-power systems capable of exciting multikilojoule laser amplifiers for the next phase of development, the Supersprite system, is briefly discussed.

scholarly journals High surface laser-induced damage threshold of SrB4O7 single crystals under 266-nm (DUV) laser irradiation

2020 ◽  
Vol 28 (20) ◽  
pp. 29239
Author(s):  
Yasunori Tanaka ◽  
Ryota Murai ◽  
Yoshinori Takahashi ◽  
Tsuyoshi Sugita ◽  
Daisetsu Toh ◽  
...  
Keyword(s):  
Single Crystals ◽  
Laser Irradiation ◽  
High Surface ◽  
Damage Threshold ◽  
Surface Laser ◽  
Laser Induced Damage

scholarly journals Direct observation of imploded core heating via fast electrons with super-penetration scheme

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
T. Gong ◽  
H. Habara ◽  
K. Sumioka ◽  
M. Yoshimoto ◽  
Y. Hayashi ◽  
...  
Keyword(s):  
Electron Beam ◽  
Direct Observation ◽  
Inertial Confinement Fusion ◽  
Short Pulse ◽  
Coupling Efficiency ◽  
High Energy ◽  
Inertial Confinement ◽  
Particle In Cell ◽  
Short Pulse Laser ◽  
Confinement Fusion

AbstractFast ignition (FI) is a promising approach for high-energy-gain inertial confinement fusion in the laboratory. To achieve ignition, the energy of a short-pulse laser is required to be delivered efficiently to the pre-compressed fuel core via a high-energy electron beam. Therefore, understanding the transport and energy deposition of this electron beam inside the pre-compressed core is the key for FI. Here we report on the direct observation of the electron beam transport and deposition in a compressed core through the stimulated Cu Kα emission in the super-penetration scheme. Simulations reproducing the experimental measurements indicate that, at the time of peak compression, about 1% of the short-pulse energy is coupled to a relatively low-density core with a radius of 70 μm. Analysis with the support of 2D particle-in-cell simulations uncovers the key factors improving this coupling efficiency. Our findings are of critical importance for optimizing FI experiments in a super-penetration scheme.

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