Research of Transport Beams Arrangement in Target Area for Large Scale ICF Facility
Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
Cited by 4 publications
References 0 publications
Purpose It is a huge technical and engineering challenge to realize the precise assembly of thousands of large optics in high power solid-state laser system. Using the 400-mm aperture-sized transport mirror as a case, this paper aims to present an intelligent numerical computation methodology for mounting performance analysis and modeling of large optics in a high-power laser system for inertial confinement fusion (ICF). Design/methodology/approach Fundamental principles of modeling and analysis of the transport mirror surface distortion are proposed, and a genetic algorithm-based computation framework is proposed to evaluate and optimize the assembly and mounting performance of large laser optics. Findings The stringent specifications of large ICF optics place very tight constraints upon the transport mirror’s assembly and mounts. The operational requirements on surface distortion [peak-to-valley and root mean square (RMS)] can be met as it is appropriately assembled by the close loop of assembly-inspection-optimization-fastening. In the end, the experimental study validates the reliability and effectiveness of the transport mirror mounting method. Originality/value In the assembly design and mounting performance evaluation of large laser optics, the whole study has the advantages of accurate evaluation and intelligent optimization on nano-level optical surface distortion, which provides a fundamental methodology for precise assembly and mounting of large ICF optics.
Purpose It is a huge technical and engineering challenge to realize the precise assembly of thousands of large optics in high power solid-state laser system. Using the 400-mm aperture-sized transport mirror as a case, this paper aims to present an intelligent numerical computation methodology for mounting performance analysis and modeling of large optics in a high-power laser system for inertial confinement fusion (ICF). Design/methodology/approach Fundamental principles of modeling and analysis of the transport mirror surface distortion are proposed, and a genetic algorithm-based computation framework is proposed to evaluate and optimize the assembly and mounting performance of large laser optics. Findings The stringent specifications of large ICF optics place very tight constraints upon the transport mirror’s assembly and mounts. The operational requirements on surface distortion [peak-to-valley and root mean square (RMS)] can be met as it is appropriately assembled by the close loop of assembly-inspection-optimization-fastening. In the end, the experimental study validates the reliability and effectiveness of the transport mirror mounting method. Originality/value In the assembly design and mounting performance evaluation of large laser optics, the whole study has the advantages of accurate evaluation and intelligent optimization on nano-level optical surface distortion, which provides a fundamental methodology for precise assembly and mounting of large ICF optics.
Capsule illumination uniformity illuminated by direct laser-driven irradiation from several tens of directions
Capsule illumination uniformity obtained by direct driving lasers from several tens of directions is studied systematically. The best polar angles of the three focal spot rings on the capsule are determined to be 22.4, 47.7, and 73.6by a spherical-harmonic mode analysis and a numerical simulation. Based on the configuration of indirect laser driven facility, we have optimized the beam re-directions and the focal spot distributions for polar direct drive, which smooth successfully the illumination distribution on the capsule.Laser driven inertial confinement fusion is an important way to achieve controllable nuclear fusion for human beings, which includes two laser-driven schemesdirectly driving and indirectly driving scheme. Since the indirect driving scheme considerably relaxes the strict requirements for laser performance and decreases the engineering difficulties, the main laser facilities around the world have adopted the indirect driving scheme, such as the National Ignition Facility in the U. S., the Laser Megajoule in France, and the SG series laser drivers in China.Meanwhile, scientists keep developing the key technologies for directly driving and have made great progress. For example, the fast ignition and shock ignition are two new methods to achieve fusion ignition in the direct driving scheme, which attracted lots of attention in the past few years. However, the main laser drivers for inertial confinement fusion research are configured as indirect drivers, which are not suitable for direct driving experiments. So a compromising suggestion was proposed that by redirecting the lasers, changing the laser energy distributions, designing new type of targets, and so on, a radiation field which is very close to a direct driving radiation field can be simulated in a laser facility that is configured as an indirect driver. This is the so called polar direct drive method that provides a feasible way for primary researches on direct driving technologies in an indirect laser driver. Such experiments have already been conducted in the National Ignition Facility.In China, the large indirect laser driver with an output capability in the level of hundreds kilojoule will finish its engineering construction and routinely operate for physical experiments soon. To achieve a good polar direct drive performance in this laser facility is much more difficult than in previous smaller laser drivers. In this paper, capsule illumination uniformity by directly driving laser from several tens of directions is studied systematically. The best polar angles of the three focal spot rings on the capsule are determined to be 22.4, 47.7, and 73.6 by a spherical-harmonic mode analysis and a numerical simulation. Based on the configuration of indirect driving laser facility, we have optimized the beam re-directions and the focal spot distributions for polar direct drive, which successfully smoothes the illumination distribution on the capsule.
A novel arrangement scheme of laser quads for spherical hohlraum in laser indirect-driven facility
In traditional laser quads arrangement schemes for spherical hohlraum in indirect-driven laser facilities, the laser quads to bring about the laser entrance hole (LEH) to close when they are incident at a large angle (55), while the complicated cross and overlap of laser quads inside the spherical hohlraum may be generated when they are incident at a small angle (35). To overcome these problems, a novel laser quads arrangement scheme for spherical hohlraum is proposed. The laser quads injected into the single LEH are divided into two cones (the incident angle of the inner cone is 35, and that of the outer cone is 55). Furthermore, the contrast and the fractional power above the intensity have been proposed to evaluate the irradiation uniformity of single laser quad, while the dispersion degree and the duty ratio are proposed to evaluate the distribution uniformity of all laser quads on the spherical hohlraum wall. Based on the beam smoothing scheme implemented by the combination of one-dimensional smoothing by spectral dispersion, the continuous phase plate and polarization control plate, the propagation model of laser quads in the spherical hohlraum has been built up, and further used to analyze the irradiation uniformity of single laser quad and all the laser quads on the spherical hohlraum wall. On this basis, the irradiation characteristics on the LEHs and the spherical hohlraum wall, and the propagation characteristic of laser quads in the novel and traditional laser quads arrangement schemes have been analyzed and compared. Results indicate that, compared with the traditional arrangement scheme of laser quads, the novel laser quads arrangement scheme has following advantages: The irradiation uniformity on the spherical hohlraum wall of single laser quad and all laser quads remains unchanged. Not only the LEH closure problem can be alleviated, but also the complicated cross and overlap of laser quads inside the spherical hohlraum in the traditional scheme could be avoided. The novel scheme may provide useful reference for the design of spherical hohlraum structure in laser indirect-driven facilities due to its obvious advantages over the traditional scheme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
Contact Info
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Product
Resources
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.
