Study of the 6.x nm short wavelength radiation spectra of laser-produced erbium plasmas for BEUV lithography

Beyond extreme ultraviolet(BEUV)radiation with a wavelength of 6.x nm for lithography is responsible for reducing the source wavelength to enable continued miniaturization of semiconductor devices.In this work,the Required BEUV light at 6.x nm wavelength was generated in dense and hot Nd:YAG laser-produced Er plasmas.The spectral contributions from the 4p–4d and 4d–4f transitions of singly,doubly and triply excited states of Er XXIV–Er XXXII in the BEUV band were calculated using Cowan and the Flexible Atomic Code.It was also found that the radiative transitions between multiply excited states dominate the narrow wavelength window around 6.x nm.Under the assumption of collisional radiative equilibrium of the laser-produced Er plasmas,the relative ion abundance in the experiment was inferred.Using the Boltzmann quantum state energy level distribution and Gram–Charlier fitting function of unresolved transition arrays(UTAs),the synthetic spectrum around 6.x nm was finally obtained and compared with the experimental spectrum.The spatio-temporal distributions of electron density and electron temperature were calculated based on radiation hydrodynamic simulation in order to identify the contributions of various ionic states to the UTAs arising from the Er plasmas near 6.x nm.

A study on soft x-ray spectra from pulsed 1 μm Nd:YAG laser-induced ytterbium plasmas

The Nd:YAG laser with a wavelength of 1.064 μm was used to generate plasmas on a high-purity solid ytterbium(70 Yb) target in a vacuum chamber. The soft x-ray time-and space-integration spectra from the Yb plasmas were measured in the wavelength range of 1.0–8.5 nm under different power densities. The atomic spectral data of the unresolved transition arrays from highly charged Yb ions were calculated based on Cowan's suite of codes, including configuration interaction. The calculated Gaussian envelope of the emission determined by the weighted spontaneous transition rates was compared with the experimental spectra, and a good agreement between them was obtained. The spatial-temporal evolutions of the plasmas under the experimental conditions are simulated based on the collisional-radiative model, enabling the understanding of the mechanism of the plasma conditions for optimal water window waveband emission output.

Research on the Application of VPython 3D Dynamic Visualization in the Teaching of College Physics

As there are numerous physics formulas in addition to them being theoretical,college students generally consider the concepts of physics as abstract,in which they are not able to apply what they have learned.For 3D dynamic animation and visualization in the teaching of college physics,VPyton has many advantages,and it provides useful exploration for students to overcome obstacles in college physics learning.Taking the teaching of simple harmonic vibration,optics,molecular thermal motion,and electric field as examples,this article discusses the application of VPython in the humancomputer interactive teaching mode of college physics,which provides a beneficial exploration and new way to improve students?engineering skills and numeracy,as well as to respond to the national“new engineering education”reform in China.

A Self-Powered Energy-Saving Epidemic Prevention Tent

The current situation of the epidemic is complex and changeable.Under the China adherence to the“dynamic zero clearance,”epidemic prevention and control is closely related to all walks of life,and epidemic prevention awning has become one of the essential basic epidemic prevention facilities.However,most of the epidemic awnings are manufactured for the isolation and protection from wind and rain,which could not meet the needs of electricity allocation during emergencies.Therefore,our goal is to design a new energy-saving epidemic prevention tent that is green,stable,and easy to shrink.It is equipped with multiple energy storage and multivariate methods to achieve self-supply of electric energy.First the“1+1”arrangement design of solar power panels on the anti-epidemic tent and pressure power panels combined with the design of pressure power panels under the tent can receive various energy inputs.At the same time,retractable brackets are designed under the four pillars,which are easy to fold and enhance the stability of the canopy.The utilization of energy is more diversified to achieve the purpose of energy conservation and emission reduction.Its market value is broad,and the development prospect is good.

MoS_(2)core-shell nanoparticles prepared through liquid-phase ablation and light exfoliation of femtosecond laser for chemical sensing

Molybdenum disulfide(MoS_(2))-based nanostructures are highly desirable for applications such as chemical and biological sensing,photo/electrochemical catalysis,and energy storage due to their unique physical and chemical properties.In this work,MoS_(2)core-shell nanoparticles were first prepared through the liquid-phase processing of bulk MoS2by a femtosecond laser.The core of prepared nanoparticles was incompletely and weakly crystalline MoS_(2);the shell of prepared nanoparticles was highly crystalline MoS_(2),which wrapped around the core layer by layer.The femtosecond laser simultaneously achieved liquid-phase ablation and light exfoliation.The formation mechanism of the core-shell nanoparticles is to prepare the nanonuclei first by laser liquid-phase ablation and then the nanosheets by light exfoliation;the nanosheets will wrap the nanonuclei layer by layer through van der Waals forces to form core-shell nanoparticles.The MoS_(2)core-shell nanoparticles,because of Mo-S bond breakage and recombination,have high chemical activity for chemical catalysis.Afterward,the nanoparticles were used as a reducing agent to directly prepare three-dimensional(3D)Au-MoS_(2)micro/nanostructures,which were applied as surface-enhanced Raman spectroscopy(SERS)substrates to explore chemical sensing activity.The ultrahigh enhancement factor(1.06×10^(11)),ultralow detection limit(10-13M),and good SERS adaptability demonstrate highly sensitive SERS activity,great ability of ultralow concentration detection,and ability to detect diverse analytes,respectively.This work reveals the tremendous potential of 3D Au-MoS_(2)composite structures as excellent SERS substrates for chemical and biological sensing.

A multi-objective study on the constructal design of non-uniform heat generating disc cooled by radial-and dendritic-pattern cooling channels

A three-dimensional disc model with non-uniform heat generating is built.A series of cooling channels are inserted to cool this disc which is strewn in a hierarchical pattern.To reveal thermal and flow characteristics,a composite objective function comprised of the maximum temperature difference(MTD)and pumping power is constructed.The deployment pattern of cooling channels contains two cases,i.e.,the radial-pattern and dendritic-pattern.By capitalizing on constructal design method together with finite element method,the diameter of radial-pattern cooling channels is optimized in the first place.Next,the diameter,angle coefficient and length coefficient of dendritic-pattern cooling channels are three degrees-of-freedom to be stepwise optimized at different heat generating conditions.Furthermore,NSGA-II algorithm is introduced into the multiobjective problem.Upon obtaining its Pareto optimal solution set,Topsis method is invoked to yield the optimal solutions under given weighted coefficients.The heat generation over the entire body and the volume ratio of cooling channels operate as the primary constraints.Based on these premises,constructal design will be stepwise performed by varying three degrees-offreedom.The obtained results state that more heating components or devices should be installed as close to the cooling water inlet as possible.This can further reduce MTD at the same cost of pumping power,thereby improve thermal and flow performance and prolong the lifespan of devices.As optimized with two degrees-of-freedom,the MTD is reduced by 18.6%compared with the counterpart obtained from single degree-of-freedom optimization,while the pumping power is increased by 59.8%.As optimized with three degrees-of-freedom,the MTD is decreased by 6.2%compared with the counterpart from two degrees-of-freedom optimization,while the pumping power is increased by 3.0%.It is manifest that when two sub-objectives form a composite objective,the performance improvement of one sub-objective will inevitably elicit the vitiation of the alternative.

通过提高湍流改善天然气发动机稀薄燃烧的光学研究

在“碳达峰”和“碳中和”的全球背景下,天然气发动机在节能减排方面显示出巨大优势。然而,天然气发动机在稀薄燃烧条件下运行时,存在燃烧稳定性较差的问题。本文在一台高压缩比的火花点火光学机上探究了提高湍流对天然气稀薄燃烧的影响。设计了可变涡流控制阀(SCV),并结合进气滚流和涡流来调节湍流方向和强度。采用粒子图像测速技术测量缸内湍流情况,并同步进行瞬态压力采集和高速摄影以量化燃烧过程。结果表明,减小SCV闭合角可以显著提高缸内湍流强度。随着湍流强度的增加,火焰传播速度和热效率显著提高,并且指示平均有效压力对火花正时不敏感。分析火焰图像发现,沿火花塞到气缸壁的径向方向上组合式湍流逐步增强,导致火核形成更早和燃烧速率更快。因此,组合式湍流具有降低天然气发动机稀薄燃烧循环变动的潜力。

量子热声制冷微循环的热力学优化

本文建立了一个考虑热漏影响的量子热声制冷微循环模型。研究主要围绕一维谐振势阱中的单个粒子展开,而系统是由无数个这样的粒子组成的。每个粒子都被限制在一定的势阱中,其出现几率可用热平衡吉布斯分布来描述。本文基于薛定谔方程推出了制冷机性能系数和制冷速率的表达式;讨论了热泄漏对循环优化性能的影响;利用Ω目标函数得出了制冷循环的最优性能区域。所得结果不仅丰富了热声理论,而且拓展了量子热力学的应用。

Influence of bubble-particle distance on the dynamic behaviors of a cavitation bubble near a particle

Cavitation and silt-erosion often co-exist, causing severe damage on fluid machinery. In this paper, the dynamic behavior of a cavitation bubble near a fixed spherical particle is numerically studied, with the focus on the influence of the stand-off distance γ on the bubble collapse morphology, micro-jet velocities and pressure on the particle. With the increase in the value of γ, the bubble profile in the collapse stage exhibits three distinct characteristics: Mushroom-shaped, pear-shaped and spherical-shaped, and the corresponding micro-jets are identified as contact jet, non-contact jet, and long-distance jet. All studied distances can be categorized into three ranges, and the typical cases in each range are demonstrated. The maximum jet velocity Vmax and the maximum pressure difference between the upper and the bottom of the particle Δpmax show the highest peak at γ = 0.9, with Vmax up to 180 m/s and Δpmax up to 10.8 MPa.