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2024
Volume: 12 Issue 1
12 Article(s)
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Detailed characterization of kHz-rate laser-driven fusion at a thin liquid sheet with a neutron detection suite | On the Cover
Benjamin M. Knight, Connor M. Gautam, Colton R. Stoner, Bryan V. Egner, Joseph R. Smith, Chris M. Orban, Juan J. Manfredi, Kyle D. Frische, Michael L. Dexter, Enam A. Chowdhury, and Anil K. Patnaik
We present detailed characterization of laser-driven fusion and neutron production ( $\sim {10}^5$ /second) using 8 mJ, 40 fs laser pulses on a thin (<1 μm) D ${}_2$ O liquid sheet employing a measurement suite. At relativistic intensity ( $\sim 5\times {10}^{18}$ W/cm ${}^2$ ) and high repetition rate (1 kHz
We present detailed characterization of laser-driven fusion and neutron production (
High Power Laser Science and Engineering
- Publication Date: Nov. 15, 2023
- Vol. 12, Issue 1, 010000e2 (2024)
Corrigendum
Optimization and control of synchrotron emission in ultraintense laser–solid interactions using machine learning – CORRIGENDUM
J. Goodman, M. King, E. J. Dolier, R. Wilson, R. J. Gray, and P. McKenna
High Power Laser Science and Engineering
- Publication Date: Feb. 16, 2024
- Vol. 12, Issue 1, 01000e12 (2024)
Letter
Analysis of mid-spatial frequency wavefront distortions from a liquid-cooled flash-lamp pumped Nd:phosphate laser amplifier
Pierre-Marie Dalbies, Sandy Cavaro, Edouard Bordenave, Nathalie Blanchot, Julien G. Moreau, and Jérôme Neauport
Mid-spatial frequency wavefront deformation can be deleterious for the operation of high-energy laser systems. When fluid cooled high-repetition-rate amplifiers are used, the coolant flow is likely to induce such detrimental mid-spatial frequency wavefront deformations. Here, we describe the design and performance of aMid-spatial frequency wavefront deformation can be deleterious for the operation of high-energy laser systems. When fluid cooled high-repetition-rate amplifiers are used, the coolant flow is likely to induce such detrimental mid-spatial frequency wavefront deformations. Here, we describe the design and performance of a 90 mm × 90 mm aperture, liquid-cooled Nd:phosphate split-slab laser amplifier pumped by flash-lamps. The performance of the system is evaluated in terms of wavefront aberration and gain at repetition rates down to 1 shot per minute. The results show that this single cooled split-slab system exhibits low wavefront distortions in the medium to large period range, compatible with a focus on target, and despite the use of liquid coolant traversed by both pump and amplified wavelengths. This makes it a potential candidate for applications in large high-energy laser facilities..
High Power Laser Science and Engineering
- Publication Date: Nov. 29, 2023
- Vol. 12, Issue 1, 010000e3 (2024)
Research Articles
Specifications and control of spatial frequency errors of components in two-beam laser static holographic exposure for pulse compression grating fabrication
Chen Hu, Songlin Wan, Guochang Jiang, Haojin Gu, Yibin Zhang, Yunxia Jin, Shijie Liu, Chengqiang Zhao, Hongchao Cao, Chaoyang Wei, and Jianda Shao
The large-aperture pulse compression grating (PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser; however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solvingThe large-aperture pulse compression grating (PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser; however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers..
High Power Laser Science and Engineering
- Publication Date: Nov. 13, 2023
- Vol. 12, Issue 1, 010000e1 (2024)
Continuous gradient fusion class activation mapping: segmentation of laser-induced damage on large-aperture optics in dark-field images
Yueyue Han, Yingyan Huang, Hangcheng Dong, Fengdong Chen, Fa Zeng, Zhitao Peng, Qihua Zhu, and Guodong Liu
Segmenting dark-field images of laser-induced damage on large-aperture optics in high-power laser facilities is challenged by complicated damage morphology, uneven illumination and stray light interference. Fully supervised semantic segmentation algorithms have achieved state-of-the-art performance but rely on a large Segmenting dark-field images of laser-induced damage on large-aperture optics in high-power laser facilities is challenged by complicated damage morphology, uneven illumination and stray light interference. Fully supervised semantic segmentation algorithms have achieved state-of-the-art performance but rely on a large number of pixel-level labels, which are time-consuming and labor-consuming to produce. LayerCAM, an advanced weakly supervised semantic segmentation algorithm, can generate pixel-accurate results using only image-level labels, but its scattered and partially underactivated class activation regions degrade segmentation performance. In this paper, we propose a weakly supervised semantic segmentation method, continuous gradient class activation mapping (CAM) and its nonlinear multiscale fusion (continuous gradient fusion CAM). The method redesigns backpropagating gradients and nonlinearly activates multiscale fused heatmaps to generate more fine-grained class activation maps with an appropriate activation degree for different damage site sizes. Experiments on our dataset show that the proposed method can achieve segmentation performance comparable to that of fully supervised algorithms..
High Power Laser Science and Engineering
- Publication Date: Nov. 20, 2023
- Vol. 12, Issue 1, 010000e4 (2024)
Digital generation of super-Gaussian perfect vortex beams via wavefront shaping with globally adaptive feedback
Rui Ma, Ke Hai Luo, Jing Song He, Wei Li Zhang, Dian Yuan Fan, Anderson S. L. Gomes, and Jun Liu
High-intensity vortex beams with tunable topological charges and low coherence are highly demanded in applications such as inertial confinement fusion (ICF) and optical communication. However, traditional optical vortices featuring nonuniform intensity distributions are dramatically restricted in application scenarios High-intensity vortex beams with tunable topological charges and low coherence are highly demanded in applications such as inertial confinement fusion (ICF) and optical communication. However, traditional optical vortices featuring nonuniform intensity distributions are dramatically restricted in application scenarios that require a high-intensity vortex beam owing to their ineffective amplification resulting from the intensity-dependent nonlinear effect. Here, a low-coherence perfect vortex beam (PVB) with a topological charge as high as 140 is realized based on the super-pixel wavefront-shaping technique. More importantly, a globally adaptive feedback algorithm (GAFA) is proposed to efficiently suppress the original intensity fluctuation and achieve a flat-top PVB with dramatically reduced beam speckle contrast. The GAFA-based flat-top PVB generation method can pave the way for high-intensity vortex beam generation, which is crucial for potential applications in ICF, laser processing, optical communication and optical trapping..
High Power Laser Science and Engineering
- Publication Date: Nov. 29, 2023
- Vol. 12, Issue 1, 010000e5 (2024)
Design, performance and application of a line-imaging velocity interferometer system for any reflector coupled with a streaked optical pyrometer system at the Shenguang-II upgrade laser facility
Dawei Yuan, Shaojun Wang, Huigang Wei, Haochen Gu, Yu Dai, Jiayong Zhong, Yutong Li, Gang Zhao, and Jie Zhang
The velocity interferometer system for any reflector (VISAR) coupled with a streaked optical pyrometer (SOP) system is used as a diagnostic tool in inertial confinement fusion (ICF) experiments involving equations of state and shock timing. To validate the process of adiabatically compressing the fuel shell through preThe velocity interferometer system for any reflector (VISAR) coupled with a streaked optical pyrometer (SOP) system is used as a diagnostic tool in inertial confinement fusion (ICF) experiments involving equations of state and shock timing. To validate the process of adiabatically compressing the fuel shell through precise tuning of shocks in experimental campaigns for the double-cone ignition (DCI) scheme of ICF, a compact line-imaging VISAR with an SOP system is designed and implemented at the Shenguang-II upgrade laser facility. The temporal and spatial resolutions of the system are better than 30 ps and 7 μm, respectively. An illumination lens is used to adjust the lighting spot size matching with the target size. A polarization beam splitter and λ/4 waveplate are used to increase the transmission efficiency of our system. The VISAR and SOP work at 660 and 450 nm, respectively, to differentiate the signals from the scattered lights of the drive lasers. The VISAR can measure the shock velocity. At the same time, the SOP system can give the shock timing and relative strength. This system has been used in different DCI campaigns, where the generation and propagation processes of multi-shock are carefully diagnosed..
High Power Laser Science and Engineering
- Publication Date: Nov. 15, 2023
- Vol. 12, Issue 1, 010000e6 (2024)
Energy enhancement of laser-driven ions by radiation reaction and Breit–Wheeler pair production in the ultra-relativistic transparency regime
Shikha Bhadoria, Mattias Marklund, and Christoph H. Keitel
The impact of radiation reaction and Breit–Wheeler pair production on the acceleration of fully ionized carbon ions driven by an intense linearly polarized laser pulse has been investigated in the ultra-relativistic transparency regime. Against initial expectations, the radiation reaction and pair production at ultra-hThe impact of radiation reaction and Breit–Wheeler pair production on the acceleration of fully ionized carbon ions driven by an intense linearly polarized laser pulse has been investigated in the ultra-relativistic transparency regime. Against initial expectations, the radiation reaction and pair production at ultra-high laser intensities are found to enhance the energy gained by the ions. The electrons lose most of their transverse momentum, and the additionally produced pair plasma of Breit–Wheeler electrons and positrons co-streams in the forward direction as opposed to the existing electrons streaming at an angle above zero degree. We discuss how these observations could be explained by the changes in the phase velocity of the Buneman instability, which is known to aid ion acceleration in the breakout afterburner regime, by tapping the free energy in the relative electron and ion streams. We present evidence that these non-classical effects can further improve the highest carbon ion energies in this transparency regime..
High Power Laser Science and Engineering
- Publication Date: Nov. 13, 2023
- Vol. 12, Issue 1, 010000e7 (2024)
A GHz chirped amplitude-modulated laser for high-contrast plasma gratings
Michael Valdman, Amir Hen, and Gilad Marcus
The generation and control of large amplitude plasma gratings and other plasma structures is of paramount importance for the realization of plasma photonics. Autoresonant excitation of such structures by means of chirped amplitude-modulated lasers has been recently discussed and analyzed theoretically. Here we discuss The generation and control of large amplitude plasma gratings and other plasma structures is of paramount importance for the realization of plasma photonics. Autoresonant excitation of such structures by means of chirped amplitude-modulated lasers has been recently discussed and analyzed theoretically. Here we discuss the parameter space for the realization of such a scheme and describe the laser system that was built towards this goal. We also expand our earlier theoretical study to account for the more realistic case of a moderately focused laser beam, instead of the simplified plane wave approximation..
High Power Laser Science and Engineering
- Publication Date: Nov. 13, 2023
- Vol. 12, Issue 1, 010000e8 (2024)
Theoretical analysis of frequency modulation-to-amplitude modulation on the final optics and target of the SG II-Up laser facility
Yujia Zhang, Wei Fan, Jiangfeng Wang, Xiaochao Wang, Xinghua Lu, Dajie Huang, Shouying Xu, Yanli Zhang, Mingying Sun, Zhaoyang Jiao, Shenlei Zhou, and Xiuqing Jiang
Frequency modulation (FM)-to-amplitude modulation (AM) conversion is an important factor that affects the time–power curve of inertial confinement fusion (ICF) high-power laser facilities. This conversion can impact uniform compression and increase the risk of damage to optics. However, the dispersive grating used in tFrequency modulation (FM)-to-amplitude modulation (AM) conversion is an important factor that affects the time–power curve of inertial confinement fusion (ICF) high-power laser facilities. This conversion can impact uniform compression and increase the risk of damage to optics. However, the dispersive grating used in the smoothing by spectral dispersion technology will introduce a temporal delay and can spatially smooth the target. The combined effect of the dispersive grating and the focusing lens is equivalent to a Gaussian low-pass filter, which is equivalent to 8 GHz bandwidth and can reduce the intensity modulation on the target to below 5% with 0.3 nm @ 3 GHz + 20 GHz spectrum phase modulation. The results play an important role in the testing and evaluating of the FM-to-AM on the final optics and the target, which is beneficial for comprehensively evaluating the load capacity of the facility and isentropic compression experiment for ICF..
High Power Laser Science and Engineering
- Publication Date: Dec. 06, 2023
- Vol. 12, Issue 1, 010000e9 (2024)
Synchronized off-harmonic probe laser with highly variable pulse duration for laser–plasma interaction experiments
J. Hornung, Y. Zobus, H. Lorenté, C. Brabetz, B. Zielbauer, and V. Bagnoud
This paper presents the development and experimental utilization of a synchronized off-harmonic laser system designed as a probe for ultra-intense laser–plasma interaction experiments. The system exhibits a novel seed-generation design, allowing for a variable pulse duration spanning over more than three orders of magnThis paper presents the development and experimental utilization of a synchronized off-harmonic laser system designed as a probe for ultra-intense laser–plasma interaction experiments. The system exhibits a novel seed-generation design, allowing for a variable pulse duration spanning over more than three orders of magnitude, from 3.45 picoseconds to 10 nanoseconds. This makes it suitable for various plasma diagnostics and visualization techniques. In a side-view configuration, the laser was employed for interferometry and streaked shadowgraphy of a laser-induced plasma while successfully suppressing the self-emission background of the laser–plasma interaction, resulting in a signal-to-self-emission ratio of 110 for this setup. These properties enable the probe to yield valuable insights into the plasma dynamics and interactions at the PHELIX facility and to be deployed at various laser facilities due to its easy-to-implement design..
High Power Laser Science and Engineering
- Publication Date: Nov. 29, 2023
- Vol. 12, Issue 1, 01000e10 (2024)
Prospect of ultrahigh-resolution fast neutron absorption spectroscopy based on a laser plasma electron accelerator
Wen-Zhao Wang, Jie Feng, Xiao-Peng Zhang, Yao-Jun Li, Wei-Jun Zhou, Wen-Chao Yan, Guo-Qiang Zhang, Chang-Bo Fu, and Li-Ming Chen
Fast neutron absorption spectroscopy is widely used in the study of nuclear structure and element analysis. However, due to the traditional neutron source pulse duration being of the order of nanoseconds, it is difficult to obtain a high-resolution absorption spectrum. Thus, we present a method of ultrahigh energy-resoFast neutron absorption spectroscopy is widely used in the study of nuclear structure and element analysis. However, due to the traditional neutron source pulse duration being of the order of nanoseconds, it is difficult to obtain a high-resolution absorption spectrum. Thus, we present a method of ultrahigh energy-resolution absorption spectroscopy via a high repetition rate, picosecond duration pulsed neutron source driven by a terawatt laser. The technology of single neutron count is used, which results in easily distinguishing the width of approximately 20 keV at 2 MeV and an asymmetric shape of the neutron absorption peak. The absorption spectroscopy based on a laser neutron source has one order of magnitude higher energy-resolution power than the state-of-the-art traditional neutron sources, which could be of benefit for precisely measuring nuclear structure data..
High Power Laser Science and Engineering
- Publication Date: Nov. 30, 2023
- Vol. 12, Issue 1, 01000e11 (2024)
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