Engineering Papers⌕ Search

Engineering topics

Meng, Xiangyu

Publications and source records attributed to Meng, Xiangyu.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Mutual optical intensity propagation through non-ideal two-dimensional mirrors

The mutual optical intensity (MOI) model is a partially coherent radiation propagation tool that can sequentially simulate beamline optics and provide beam intensity, local degree of coherence and phase distribution at any location along a beamline. This paper extends the MOI model to non-ideal twodimensional (2D) optical systems, such as ellipsoidal and toroidal mirrors with 2D figure errors. Simulation results show that one can tune the trade-off between calculation efficiency and accuracy by varying the number of wavefront elements. The focal spot size of an ellipsoidal mirror calculated with 100 $\times$ 100 elements gives less than 0.4% deviation from that with 250 $\times$ 250 elements, and the computation speed is nearly two orders of magnitude faster. Effects of figure errors on 2D focusing are also demonstrated for a non-ideal ellipsoidal mirror and by comparing the toroidal and ellipsoidal mirrors. Finally, the MOI model is benchmarked against the multi-electron Synchrotron Radiation Workshop (SRW) code showing the model’s high accuracy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

In-plane wavevector distribution in partially coherent X-ray propagation

The MOI ( Mutual Optical Intensity ) code for propagating partially coherent radiation through beamline optics is updated by including the in-plane wavevector in the wavefield calculation. The in-plane wavevector is a local function and accurately describes the average phase distribution in a partially coherent wavefield. The improved MOI code is demonstrated by beam propagation through free space and non-ideal mirrors. Here, the improved MOI code can provide more accurate results with lower numbers of elements, and thus has a higher calculation efficiency. Knowledge of the in-plane wavevector also enables detailed studies of wavefield information under different coherence conditions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Influence of Temperature on Sr{sub 0.35}La{sub 0.40}Ca{sub .25}Fe{sub 11.6}Co{sub 0.4}O{sub 19} Hexagonal Ferrites Against Structural, Morphological and Magnetic Properties Prepared by Conventional Ceramic Reaction Methodology

Conventional Ceramic Reaction Methodology has been utilized for the preparation of M-type hexagonal ferrites of Sr{sub 0.35}La{sub 0.40}Ca{sub 0.25}Fe{sub 11.6}Co{sub 0.4}O{sub 19} magnets. X-ray diffraction has been performed for phase determination of the magnetic powders. At calcination temperatures ranging from 1220 to 1330 {sup ∘}C, the synchronize compost of the magnetic powders comprised of M-type hexagonal ferrites together with a small amount of impurity phase such as α-Fe{sub 2}O{sub 3} were co-existed. At calcination temperature above 1270 {sup ∘}C, single-phase M-type hexaferrites can be obtained. The particles seemed to be in a hexagonal plate-like mould which spread-out homogeneously were examined by field emission scanning electron microscopy. The magnetic edibility of the magnetic powders was intended by permanent magnetic measurement test equipment vibrating sample magnetometer. Magnetic properties, such as specific saturation magnetization, coercivity and remanence were temperature-dependent. However, with the increase of sintering temperature, i.e. above 1270 {sup ∘}C, saturation magnetization was increased while the coercivity showed reversed order.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Effect of the Fe/Ba Ratio and Sintering Temperature on Microstructure and Magnetic Properties of Barium Ferrites Prepared by Hydrothermal Method

Magnetoplumbite-type (M-type) hexagonal barium ferrite particles were synthesized by a hydrothermal method. The structure and magnetic properties of barium ferrites were investigated systematically, which indicated that the ratio of Fe/Ba (R{sub F/B}) and sintering temperature have an important effect on structure and performance. Phase composition, micro-morphology, and magnetic properties of the particles were investigated by X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). When the ratio of Fe/Ba (R{sub F/B}) is even low or high, inferior images of XRD could be attained with certain impurities. When R{sub F/B} = 8, the single phase could be obtained without impurities. Micro-morphology of the particles exhibits the uniform plane hexagonal structures of nano-sized M-type ferrites when sintered at 800 °C. Saturation magnetization (M{sub s}) reaches the maximum value at R{sub F/B} = 7 (M{sub s} = 45.07 emu/g). The value of coercivity (H{sub c}) increases with the growth of R{sub F/B}, and H{sub c} is up to 6207 Oe when R{sub F/B} = 7. The effect of R{sub F/B} and temperature on magnetization (M{sub s}) and coercivity (H{sub c}) was studied in this paper.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Mutual optical intensity propagation through non-ideal mirrors

The mutual optical intensity (MOI) model is extended to include the propagation of partially coherent radiation through non-ideal mirrors. The propagation of the MOI from the incident to the exit plane of the mirror is realised by local ray tracing. The effects of figure errors can be expressed as phase shifts obtained by either the phase projection approach or the direct path length method. Using the MOI model, the effects of figure errors are studied for diffraction-limited cases using elliptical cylinder mirrors. Figure errors with low spatial frequencies can vary the intensity distribution, redistribute the local coherence function and distort the wavefront, but have no effect on the global degree of coherence. The MOI model is benchmarked against HYBRID and the multi-electron Synchrotron Radiation Workshop ( SRW ) code. The results show that the MOI model gives accurate results under different coherence conditions of the beam. Other than intensity profiles, the MOI model can also provide the wavefront and the local coherence function at any location along the beamline. The capability of tuning the trade-off between accuracy and efficiency makes the MOI model an ideal tool for beamline design and optimization.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗