Status of cleanliness maintaining in target beam enclosures in SG III facilities and contamination sources analysis

Wang, Meicong; Baoxu, Wang; Miao, Xinxiang; Cheng, Xiaofeng; Wu, Wenkai

doi:10.1117/12.2072417

Cited by 5 publications

(6 citation statements)

References 2 publications

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“…We conducted the experiments in a cleanroom with a level 100 (the number of particles with a diameter larger than 0.1 μm cannot exceed 100 [5]). An industrial-grade super gas knife (110,012 series, 1.7 Mpa maximum input pressure, EXAIR Corporation) supported by an external gas system filled with nitrogen, was utilized to produce the protection flow field.…”

Section: Surface Protection Experimentsmentioning

confidence: 99%

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Low-speed gas knife protection for the large aperture optical component in high-power laser systems

Gao

Dong

et al. 2023

Front. Phys.

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In high-power laser systems, fused silica aerosols produced by laser-induced damage to optical components impede further improvement in operation efficiency. To mitigate aerosol threats, low-speed gas knives are an attractive online option. Herein, we investigate the protective mechanism of a low-speed gas knife (<20 m/s) against aerosol invasion on the optical component. First, aerosol particles invaded the surface experimentally in two ways and were detected both in the core and non-core regions, depending on the coverage area of the protection flow. Particle sedimentation percentages can directly reflect the protection capability of the gas knife flow. Since a “midstream defect” is readily apparent, a CFD model was developed to explain the phenomenon from the perspective of velocity distribution. Additionally, the Euler-Lagrange method was used to track airflow particle motions and reappear the protective process. The numerical and experimental results on protection efficiency are closely correlated. The numerical calculation indicates that the “midstream defect” manifested in the core region is possibly attributed to the turbulent dispersion and anisotropic near-wall effects of particles of various diameters, while in the non-core region, the mechanism differs. This work provides a framework for airflow clean designs inside high-power laser systems.

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Section: Surface Protection Experimentsmentioning

confidence: 99%

“…Inertial confinement fusion (ICF) ignited by a high-power laser system, such as the NIF [1], LMJ [2], or SG series [3,4], is an efficient way to achieve clean and controllable energy. A key constraint on ignition threshold is the degradation of cleanliness levels inside laser systems [5]. Many factors are declining the cleanliness levels.…”

Section: Introductionmentioning

confidence: 99%

Low-speed gas knife protection for the large aperture optical component in high-power laser systems

Gao

Dong

et al. 2023

Front. Phys.

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“…Multipass amplification systems have the advantages of peak power, high efficiency, low loss transmission, and high beam quality in the fields of highenergy-density physics and astrophysics 1,2 . For example, the XG Ⅲ [3][4][5] and SG Ⅲ devices 6,7 of China, and the National Ignition (NIF) 8 and HiPER devices 9 of the European Union.…”

Section: Introductionmentioning

confidence: 99%

Propagation and amplification law of undetermined stray light and influence of signal-to-noise ratio in a multipass amplifier system

Wang

Xie

Huang

et al. 2023

Preprint

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Multipass amplifier systems in areas such as high-energy-density physics and astrophysics play an important role, but the undetermined stray light caused by defects seriously influencing the output signal-to-noise ratio (SNR) and even resulting in the failure of the main pulse bombardment. In this study, the modulation of nondeterministic stray light caused by the defects in the optical paths of different components in a multipass amplifier system was examined, and a Mie scattering model of multi-crack defects established. Using ray-tracing simulation, the spatial and temporal distribution of stray light was analysed, and experimental verification was conducted. The law of energy amplification for nondeterministic stray light caused by component defect modulation and an empirical formula for the signal to noise ratio of the pre-pulse system were established. This study provides a reference for the accurate troubleshooting of components, optical path defects and an important theoretical basis for the processing and correction of system components.

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“…Further studies by Zhu et al [ 25 ] divided the laminar flow loop into two rounds and tested it online, revealing a significant improvement in particle elimination and creating a more stable environment in terms of temperature, humidity, and pressure within the final optics assembly. Wang et al [ 26 ] used laminar flow to evaluate the sedimentation efficiency of suspended particles near upward-facing mirrors. They found that after 10 h of ventilation, the cleanliness level returned to Class 100.…”

Section: Introductionmentioning

confidence: 99%

“…(e.g., how to ascertain a particle’s initial speed along the transient timelines), and the lack of accurate models to predict particle long-range movement, impede further research in this area. On the other hand, in terms of the purge pattern, despite some studies demonstrating that non-unidirectional laminar flow can effectively entrain particles in high-power laser facilities (e.g., laminar flow background and high-speed gas knife can maintain cleanliness for upward-facing mirrors [ 13 , 26 , 27 ]), there is a dearth of research on the relationship between the protection mechanisms of laminar flow and the aerodynamic properties of aerosol particles in different directions (including gravitational). Take ref.…”

Section: Introductionmentioning

confidence: 99%

Surface Cleanliness Maintenance with Laminar Flow Based on the Characteristics of Laser-Induced Sputtering Particles in High-Power Laser Systems

Gao

Dong

et al. 2023

Micromachines

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In high-power laser systems, the primary cause of contamination of optical components and degradation of spatial cleanliness is laser-induced sputtering of particles. To mitigate this problem, laminar flow is frequently utilized to control the direction and transport of these particles. This study characterizes the properties of laser-induced sputtering particles, including their flying trend, diameter range, and velocity distribution at varying time intervals. A time-resolved imaging method was employed to damage the rear surface of fused silica using a 355 nm Nd: YAG pump laser. The efficacy of laminar flow in controlling these particles was then assessed, with a particular focus on the influence of laminar flow direction, laminar flow velocity, particle flight height, and particle diameter. Our results indicate that the optimal laminar flow velocity for preventing particle invasion is highly dependent on the maximum particle attenuation distance (or safety distance), which can vary by up to two orders of magnitude. Furthermore, a laminar flow velocity of 0.5 m/s can effectively prevent particle sedimentation. Future research will aim to optimize laminar flow systems based on these findings to achieve high surface cleanliness in high-power laser systems with minimal energy consumption.

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Status of cleanliness maintaining in target beam enclosures in SG III facilities and contamination sources analysis

Cited by 5 publications

References 2 publications

Low-speed gas knife protection for the large aperture optical component in high-power laser systems

Low-speed gas knife protection for the large aperture optical component in high-power laser systems

Propagation and amplification law of undetermined stray light and influence of signal-to-noise ratio in a multipass amplifier system

Surface Cleanliness Maintenance with Laminar Flow Based on the Characteristics of Laser-Induced Sputtering Particles in High-Power Laser Systems

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