分类： 核科学技术 >> 核科学与技术 分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-05
摘要： Space objects, such as spacecraft or missiles, might be exposed to intense X-rays in outer space, leading to severe damage. How to reinforce these objects to reduce damage from X-ray irradiation is a significant concern. Blow-off impulse (BOI) is a crucial physical quantity for investigating the material damage induced by X-ray irradiation. However, the accurate calculation of the BOI is a challenge, particularly for the large deformation of materials with complex configurations. In this paper, we develop a novel two-dimensional Particle-in-Cell (PIC) code, Xablation2D, to calculate the BOIs under far-field X-ray irradiation. This significantly reduces the dependence on grid shape for numerical simulation. The reliability of this code is verified by the simulation results from the open-source codes, and the calculated BOIs are consistent with experimental and analytical results.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Tengfang Kuang
Ran Huang
Wei Xiong
Yunlan Zuo
Xiang Han
Franco Nori
Cheng-Wei Qiu
Hui Luo
Hui Jing
Guangzong
Xiao
摘要： Phonon lasers, exploiting coherent amplifications of phonons, have been a cornerstone for exploring nonlinear phononics, imaging nanomaterial structures, and operating phononic devices. Very recently, by levitating a nanosphere in an optical tweezer, a single-mode phonon laser governed by dispersive optomechanical coupling has been demonstrated, assisted by alternating mechanical nonlinear cooling and linear heating. Such levitated optomechanical (LOM) devices, with minimal noises in high vacuum, can allow flexible control of large-mass objects without any internal discrete energy levels. However, untill now, it is still elusive to realize phonon lasing with levitated microscale objects, due to much stronger optical scattering losses. Here, by employing a Yb3+-doped active system, we report the first experiment on nonlinear multi-frequency phonon lasers with a micro-size sphere governed instead by dissipative LOM coupling. In this work, active gain plays a key role since not only 3-order enhancement can be achieved for the amplitude of the fundamental-mode phonon lasing, compared with the passive device, but also nonlinear mechanical harmonics can emerge spontaneously above the lasing threshold. Furthermore, for the first time, coherent correlations of phonons are observed for both the fundamental mode and its harmonics. Our work drives the field of LOM technology into a new regime where it becomes promising to engineer collective motional properties of typical micro-size objects, such as atmospheric particulates and living cells, for a wide range of applications in e.g., acoustic sensing, gravimetry, and inertial navigation.
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