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In this work, we studied the x‐ray energy dependence of x‐ray beam diameter focused by polycapillary optics. A quantitative beam diameter–energy relation enables more accurate estimation of the element‐specific interrogation area of a sample using the compositional maps produced by a micro‐XRF system. This improves upon our ability to visualize individual beam‐diameter sized mineral grains and in turn directly benefits Planetary Instrument for X‐ray Lithochemistry (PIXL) analyses of martian soil in addition to benefitting other micro‐focused x‐ray fluorescence (XRF) systems. The spatial distribution of an array of characteristic XRF emission lines was measured by sampling via a knife‐edge approach with small motor stepping of the beam across target edges. Data taken as part of this effort, from the Planetary Flight Model (PFM), were limited to only seven beam energies corresponding to the elements Ni, Cu, Se, Ta, Au, Ti and Ba. Hence, we conducted additional analysis using JPL's lab‐based breadboard (LBB) micro‐XRF system, a system that emulates PIXL's functionality where we measured beam diameter corresponding to 18 elements: Na, Mg, Al, Si, Cl, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, Se, Sr and Mo. The experimental results were also compared with Monte Carlo simulations. The beam diameter (y)–energy (x) relation that we obtained for LBB was y = 185.79 exp(−0.078x) whose exponential component was then used to get a more accurate relation for the PFM even with the limited data set: y = 227.53 exp(−0.078x). The difference in the two coefficients for the PFM and LBB stems mainly from the difference in the polycapillary optic design, and this work establishes x‐ray beam diameter versus energy relation quantitatively for both the systems. [ABSTRACT FROM AUTHOR]

Propagation properties of Cosine‑hyperbolic Vortex Gaussian Beams propagating in turbulent atmosphere are investigated. In this context, the effect of topological charges and decentred parameters on the beam size and the kurtosis parameter is evaluated. It is obtained that, beams with bigger topological charges face additional beam spreading, as well as a decrease in the kurtosis parameter. On the other hand, as the decentred parameter increases, beams spread less in long communication links. Inversely, Kurtosis parameters increase especially as the decentred parameters is greater than 1.5. Up to this end, the presented results are critical for both the design and the performance improvement of the free-space optical communication systems. [ABSTRACT FROM AUTHOR]

Here we analyzed the intensity profile properties of the Laguerre-Gaussian (LG) mode laser beams, to facilitate the intracavity intensity modulation for high-order LG mode laser output. The commonly used definitions of ring-like beam size are discussed, including the second moment of light intensity, power in the bucket, and the peak intensity radius of the ring-like beam. The differences between these methods underscore the importance of selecting appropriate beam size definitions when estimating the mode order, which is particularly worthy of attention when employing certain mode-selection techniques, such as using a defect spot, an aperture, or inducing spherical aberration (SA), to achieve high-order mode outputs. In the experiment, high-order mode LG 0,± m output were obtained by utilizing the SA of a short-focal lens in the cavity of an end-pumped Nd:YVO 4 laser at 1064 nm. The highest angular indices m reached 355, which is the highest order of LG mode output obtained directly from a laser cavity. The experimental relationship between the mode-order and cavity parameters matched well with the theoretical results, validating the analysis of the intensity profile properties. [ABSTRACT FROM AUTHOR]

A beam size estimation method for mid-infrared lasers is proposed. The light-receiving surface of a silicon-based photonic semiconductor image sensor is irradiated with a mid-infrared laser beam to be measured. The semiconductor substrate is heated and excites thermal carriers at the laser incident spot. The distribution of excited carriers is captured and visualized as a monochromatic image by the image sensor. Demonstration using a carbon dioxide laser showed a correlation between the diameter of distributed thermal carriers and that of the incident laser beam with Gaussian distribution. The results indicated that the proposed method is effective for the estimation of beam diameter of mid-infrared lasers. [ABSTRACT FROM AUTHOR]

Preplaced aggregate fibrous concrete (PAFC) is a revolutionary kind of concrete composite that is gaining popularity and attracting the interest of academics from across the world. PAFC is a uniquely designed concrete prepared by stacking and packing premixed fibers and coarse aggregate in a steel mold. The gaps between the fibers and aggregates are subsequently filled by injecting a cement grout with high flowability. This study investigates the impact performance of three different sizes of PAFC beams. Steel and polypropylene fibers were used in a 3% dosage to make three different beam sizes, measuring 550 × 150 × 150 mm, 400 × 100 × 100 mm, and 250 × 50 × 50 mm. According to ACI Committee 544, all beams were subjected to a drop weight flexural impact test. Compressive strength, impact energies at initial crack and failure, ductility index, and failure mode were evaluated. Additionally, analytical modeling was used to compute the failure impact energy for the fibrous beams. The results showed that the addition of fibers increased the capacity of the tested beams to absorb greater flexural impact energy. Compared to polypropylene fibers, steel fibers had better crack propagation and opening resistance because of their higher tensile strength and crimped and hooked end configuration. For all large-size beams, the analysis of the percentage increase in impact energy at the failure stages was found to be 5.3 to 14.6 times higher than the impact energy at cracking. [ABSTRACT FROM AUTHOR]

In this paper, we study the beam evolution, size, scintillation index, and signal-to-noise ratio (SNR) of Finite Energy Airy-Hermite-Hollow Gaussian Beam (FAHHGB) in turbulence. We utilize numerical turbulence modeling for the transmission medium. We observe that FAHHGB evolves rapidly in turbulence. In addition, we see that beam size can be controlled by adjusting the beam order, hollowness, and scaling parameters. We obtain more concentrated beams when the scaling parameter increases. In terms of scintillation, the beam provides significantly low scintillation. Especially when the hollowness parameter is high, we found that the scintillation index of FAHHGB remains below the Gauss beam. This means that FAHHGB has higher SNR than Gauss beam, particularly at long distances. We anticipate that this complete analysis will be helpful for free space optics link designers. [ABSTRACT FROM AUTHOR]

Preplaced aggregate fibrous concrete (PAFC) is a revolutionary kind of concrete composite that is gaining popularity and attracting the interest of academics from across the world. PAFC is a uniquely designed concrete prepared by stacking and packing premixed fibers and coarse aggregate in a steel mold. The gaps between the fibers and aggregates are subsequently filled by injecting a cement grout with high flowability. This study investigates the impact performance of three different sizes of PAFC beams. Steel and polypropylene fibers were used in a 3% dosage to make three different beam sizes, measuring 550 × 150 × 150 mm, 400 × 100 × 100 mm, and 250 × 50 × 50 mm. According to ACI Committee 544, all beams were subjected to a drop weight flexural impact test. Compressive strength, impact energies at initial crack and failure, ductility index, and failure mode were evaluated. Additionally, analytical modeling was used to compute the failure impact energy for the fibrous beams. The results showed that the addition of fibers increased the capacity of the tested beams to absorb greater flexural impact energy. Compared to polypropylene fibers, steel fibers had better crack propagation and opening resistance because of their higher tensile strength and crimped and hooked end configuration. For all large-size beams, the analysis of the percentage increase in impact energy at the failure stages was found to be 5.3 to 14.6 times higher than the impact energy at cracking.

Various modulation approaches, such as amplitude and frequency modulations, have been applied widely to modify the acoustic field and improve the performance of ultrasound imaging and therapy. However, phase modulation (PM) has not been investigated extensively in the ultrasound applications, especially at a long-pulse duration. In this study, the effects of PM on the acoustic field were investigated. The radiated acoustic pressure waveforms produced using different PM strategies (i.e., sequential phase inversion every cycle, every two cycles, and random phase inversion) were explored, and the distributions of acoustic pressure and average acoustic intensity along and transverse to the transducer axis were compared with those of a sinusoidal wave excitation in both measurement and simulation. It is found that the phase inversion between the modulated signals is not clearly seen in the radiated waveform because of the limited fractional bandwidth of the therapeutic ultrasound transducer. As a result, the radiated waveform has a higher oscillating frequency, and the pressure at the focus and the −6-dB beam size are decreased. Both simulation and measurement show similar trends. Furthermore, produced acoustic fields of the phased array using these PM strategies were also simulated at the varied lateral and axial focus shifting distances. The magnitude and beam size of both the main lobe and grating lobe are found between them, especially at the large focus shifting. In summary, the acoustic field is dependent on the PM, and the appropriate excitation scheme could improve the ultrasound application. [ABSTRACT FROM AUTHOR]

In this paper we demonstrate that the size of a laser beam, which increases with propagation due to diffraction induced divergence, carrying a given phase profile, can be predicted and the same can be validated experimentally. Since an arbitrary phase profile is also a linear combination of a set of Zernike polynomials hence the divergence corresponding to each Zernike mode can be utilized to estimate the effective size of the beam carrying the arbitrary phase profile. Numerical simulation using the scalar diffraction theory shows how a laser beam with a certain Zernike mode describing its phase profile diverges. Observations from numerical simulations lead to construction of a functional form that can predict the effective size of a laser beam carrying a specific Zernike mode in its phase profile, at different propagation distances. In this paper we develop an experimental arrangement to holographically incorporate a specific phase profile into an incident laser beam. We utilize the programmable control of the beam size for a given propagation distance to achieve different Fresnel numbers. We further develop a detector assembly which can be used to measure the effective size of the beam in the observation plane. We then show experimentally that the effective size of a laser beam propagating distances corresponding to different Fresnel numbers and carrying a known phase profile, described either by a single Zernike mode or a random combination of several Zernike modes, can be very well predicted by the functional form even in a realistic scenario. [ABSTRACT FROM AUTHOR]

Single Particle Irradiation system to Cell (SPICE) facility at the National Institute of Radiological Sciences (NIRS) provides a magnetically focused 3.4 MeV proton microbeam. Throughout the radiobiological studies using SPICE over the years, we have realized that biological effect can be affected by the highly localized dose distribution of the microbeam and results may differ from that of broad beam irradiation. Previously, we have reported that the beam size of the SPICE microbeam was approximately 2 µm in diameter; the proton traversal was identified as etch pits produced on plastic nuclear track detectors, CR-39. However, this widely used method cannot distinguish individual proton tracks of highly focused microbeam due to the overlapping of etch pits, which was major limitation for beam size analysis as well as estimation of localized dose distribution in the cells. To overcome this limitation, we used fluorescent nuclear track detectors (FNTD; Al 2 O 3 : C, Mg) to investigate the beam size and its proton-number dependence (7–1000 protons per position). Detail analysis of Z(optical axis)-stacks of fluorescent images of the FNTD with a confocal laser scanning microscope clearly demonstrated that FNTDs has better spatial resolution and detection sensitivity compared to the conventional CR-39 detectors. The overall beam size was evaluated as elliptical shape or rectangular shape and determined to be in the range of 2.0 × 1.5–3.1 × 2.4 μm, depending on the number of protons per position. This result suggests that out-focused fraction of the incident protons contributes the broadening of the beam size. Throughout the present study, the FNTD irradiation and related image processing technology have demonstrated the feasibility of high-resolution measurement of the microbeam size over a wide range of the microbeam intensity. [ABSTRACT FROM AUTHOR]

Containership size has been increasing in length, width (beam), and height. The introduction of Ultra Large Containerships results in a much larger number of containers stowed in a cargo bay. The objective of this paper is to determine the impact of the increasing containership bay size on the economies of scale at berth. We develop the concept of bay time, the amount of time it takes to load and discharge the largest cargo bay of a containership based on bay size, in order to determine the minimum amount of time it takes to discharge and load a containership. The analysis establishes that bay time is the foundation and critical path of the minimum amount of time a containership must stay at berth and in port. The study notes that, inherently, an increase in containership bay size involves diseconomies of scale in cargo handling operations, at a given level of gantry crane productivity. We find that there are increasing diseconomies of scale for large containerships at berth. The study also establishes that: as beam/bay size increases, the average cargo handling time of two bays increases by an average of 4.5 h at any productivity level. Bay time declines as crane productivity increases up to the crane’s technological constraint. Furthermore, the larger the beam/bay, the larger the marginal benefits when productivity increases. The diseconomies of scale are stable and predictable at every gantry crane productivity level. The study recommends using bay time as the fundamental measure for containership performance at berth and in port, as well as for voyage planning. [ABSTRACT FROM AUTHOR]

Experiments were conducted to study the weldability of a 50 μm-thick AM350 stainless steel foil onto a 1 mm-thick SUS304 stainless steel sheet using a 2 kW multi-mode fiber laser. To enhance the contact between the foil and the substrate, a vacuum-assisted jig was designed and used, and four different beam diameters (200, 375, 625, and 1125 μm) were considered to study the effect of beam size on weldability. For each beam diameter, a process parameter space consisting of 25 experiments was constructed systematically such that the constructed spaces for different beam diameters were qualitatively similar in terms of penetration depth and welding mode. High-speed video imaging was utilized to study the mechanisms of melt pool disruption and droplet formation, and dust and cavity distributions on the specimens were also investigated. It was found that the effect of beam diameter is significant in the ultra-thin foil welding, and a smaller diameter is highly preferred. For larger beams, the surface tension effect becomes too large to sustain a stable weld pool. Tensile strength and hardness were found to be inversely proportional to the penetration depth. [ABSTRACT FROM AUTHOR]

The projected emittance (2D) and the intrinsic emittance (4D) reconstruction method by using the beam size measurements at different locations is analyzed in order to study analytically the conditions of solvability of the systems of equations involved in this process. Some conditions are deduced and discussed, and general guidelines about the locations of the measurement stations have been obtained to avoid unphysical results. The special case of the multi-Optical Transition Radiation system (m-OTR), made of four measurement stations, in the Extraction Line (EXT) of Accelerator Test Facility 2 (ATF2) has been simulated in much detail and compared with measurements. Finally a feasibility study of a multi-station system for fast transverse beam size measurement, emittance reconstruction and coupling correction in the Ring to Main Linac (RTML) of International Linear Collider (ILC) Diagnostic sections of the RTML has been discussed in detail. [ABSTRACT FROM AUTHOR]

The use of ultrarelativistic electron (positron) emission in thin crystals to estimate particle beam spatial sizes for projected electron–positron colliders is proposed. The existing position-sensitive X-ray range detectors restrict the minimum value of the measured beam size to a level of approximately 10 μm, which is far greater than the planned sizes of collider beams. We propose to estimate the electron (positron) beam divergence over the diffracted transition radiation from angular distribution measurements. The spatial size can be obtained from the calculated beam emittance or the experimental emittance, which is measured during the earlier stage of acceleration using optical transition or optical diffraction radiation. The problem of crystal destruction under the influence of a high-intensity electron beam is discussed. The use of surface parametric X-ray radiation, where the problem of crystal destruction is almost absent, to measure the electron beam parameters is also discussed. [ABSTRACT FROM AUTHOR]