WorldWideScience

Sample records for beam shaping

  1. Wavelength-independent laser beam shaping

    CSIR Research Space (South Africa)

    Degama, MP

    2010-07-01

    Full Text Available This paper presents a beam shaping device namely, a Diffractive Optical Element (DOE), which is used to change a beam having a Gaussian intensity profile into a beam with a uniform intensity profile. The DOE used in this work was fabricated from Zn...

  2. Beam Loss and Beam Shape at the LHC Collimators

    CERN Document Server

    Burkart, Florian

    In this master thesis the beam loss and the beam shape at the LHC collimators was measured, analysed, presented and discussed. Beginning with a short introduction of the LHC, the experiments, the supercon- ducting magnet system, the basics on linear beam dynamics and a describtion of the LHC collimation system are given. This is followed by the presentation of the performance of the LHC collimation sys- tem during 2011. A method to convert the Beam Loss Monitor signal in Gy/s to a proton beam loss rate will be introduced. Also the beam lifetime during the proton physics runs in 2011 will be presented and discussed. Finally, the shape of the LHC beams is analysed by using data obtained by scraping the beam at the LHC primary collimators.

  3. What Makes a Beam Shaping Problem Difficult

    International Nuclear Information System (INIS)

    Romero, Louis; Dickey, Fred M.

    2000-01-01

    The authors have discussed the three factors that they believe are the most important in determining the difficulty of a beam shaping problem: scaling, smoothness, and coherence. The arguments have been almost completely based on considering how these factors influence beam shaping lenses that were designed using geometrical optics. However, they believe that these factors control the difficulty of beam shaping problems even if one does not base ones design strategy on geometrical optics. For example, they have shown that a lens designed using geometrical optics will not work well unless β is large. However, they have also shown that if β is small the uncertainty principle shows that it is impossible to do a good job of beam shaping no matter how one designs ones lens

  4. Optical fiber designs for beam shaping

    Science.gov (United States)

    Farley, Kevin; Conroy, Michael; Wang, Chih-Hao; Abramczyk, Jaroslaw; Campbell, Stuart; Oulundsen, George; Tankala, Kanishka

    2014-03-01

    A large number of power delivery applications for optical fibers require beams with very specific output intensity profiles; in particular applications that require a focused high intensity beam typically image the near field (NF) intensity distribution at the exit surface of an optical fiber. In this work we discuss optical fiber designs that shape the output beam profile to more closely correspond to what is required in many real world industrial applications. Specifically we present results demonstrating the ability to transform Gaussian beams to shapes required for industrial applications and how that relates to system parameters such as beam product parameter (BPP) values. We report on the how different waveguide structures perform in the NF and show results on how to achieve flat-top with circular outputs.

  5. Doppler-shifted neutral beam line shape and beam transmission

    International Nuclear Information System (INIS)

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O'Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-α line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3 degrees (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9 degrees. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9 degrees. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of ∼75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2 degrees, rather than the 4.95 degrees subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence

  6. Annular beam shaping and optical trepanning

    Science.gov (United States)

    Zeng, Danyong

    Percussion drilling and trepanning are two laser drilling methods. Percussion drilling is accomplished by focusing the laser beam to approximately the required diameter of the hole, exposing the material to one or a series of laser pulses at the same spot to melt and vaporize the material. Drilling by trepanning involves cutting a hole by rotating a laser beam with an optical element or an x-y galvo-scanner. Optical trepanning is a new laser drilling method using an annular beam. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a traditional circular laser beam. Heating depth is important for drilling application. Since there are no good ways to measure the temperature inside substrate during the drilling process, an analytical model for optical trepanning has been developed by considering an axisymmetric, transient heat conduction equation, and the evolutions of the melting temperature isotherm, which is referred to as the melt boundary in this study, are calculated to investigate the influences of the laser pulse shapes and intensity profiles on the hole geometry. This mathematical model provides a means of understanding the thermal effect of laser irradiation with different annular beam shapes. To take account of conduction in the solid, vaporization and convection due to the melt flow caused by an assist gas, an analytical two-dimensional model is developed for optical trepanning. The influences of pulse duration, laser pulse length, pulse repetition rate, intensity profiles and beam radius are investigated to examine their effects on the recast layer thickness, hole depth and taper. The ray tracing technique of geometrical optics is employed to design the necessary optics to transform a Gaussian laser beam into an annular beam of different intensity profiles. Such profiles include half Gaussian with maximum intensities at the inner and outer

  7. Improvement of Galilean refractive beam shaping system for accurately generating near-diffraction-limited flattop beam with arbitrary beam size.

    Science.gov (United States)

    Ma, Haotong; Liu, Zejin; Jiang, Pengzhi; Xu, Xiaojun; Du, Shaojun

    2011-07-04

    We propose and demonstrate the improvement of conventional Galilean refractive beam shaping system for accurately generating near-diffraction-limited flattop beam with arbitrary beam size. Based on the detailed study of the refractive beam shaping system, we found that the conventional Galilean beam shaper can only work well for the magnifying beam shaping. Taking the transformation of input beam with Gaussian irradiance distribution into target beam with high order Fermi-Dirac flattop profile as an example, the shaper can only work well at the condition that the size of input and target beam meets R(0) ≥ 1.3 w(0). For the improvement, the shaper is regarded as the combination of magnifying and demagnifying beam shaping system. The surface and phase distributions of the improved Galilean beam shaping system are derived based on Geometric and Fourier Optics. By using the improved Galilean beam shaper, the accurate transformation of input beam with Gaussian irradiance distribution into target beam with flattop irradiance distribution is realized. The irradiance distribution of the output beam is coincident with that of the target beam and the corresponding phase distribution is maintained. The propagation performance of the output beam is greatly improved. Studies of the influences of beam size and beam order on the improved Galilean beam shaping system show that restriction of beam size has been greatly reduced. This improvement can also be used to redistribute the input beam with complicated irradiance distribution into output beam with complicated irradiance distribution.

  8. "Intelligent" Automatic Beam Steering and Shaping

    CERN Document Server

    Jansson, A

    2000-01-01

    The strategy for Automated Beam Steering and Shaping (ABS) in the PS complex is to use theoretical response matrices calculated from an optics database. The main reason for this is that it enforces a certain understanding of the machine optics. A drawback is that the validation of such a matrix can be a lengthy process. However, every time a correction is made using an ABS program, a partial measurement of the response matrix is effectively performed. Since the ABS programs are very frequently used, the full matrices could thus be measured on an almost daily basis, provided this information is retained. The information can be used in two ways. Either the program passively logs the data to be analysed off­line, or the information is directly fed back to the matrix, which makes the program 'learn' as it executes. The data logging provides a powerful machine debugging tool, since deviations between the measured and theoretical matrices can be traced back to incorrect optical parameters. The 'learning' mode ensu...

  9. Laser beam shaping design based on micromirror array

    Science.gov (United States)

    Fang, Han; Su, Bida; Liu, Jiaguo; Fan, Xiaoli; Jing, Wang

    2017-10-01

    In the practical application of the laser, it is necessary to use the laser beam shaping technology to shape the output beam of laser device to the uniform light intensity distribution. The shaping divergent optical system of compound eye integrator way is composed of beam expanding mirror group and lens array. Its working principle is to expand the output laser to a certain size of caliber, and then divide the beam with lens array into multiple sub beam, where the lens unit of lens array can control the divergence angle of sub beam through the design of focal length, with mutual superposition of the sub beam in far field, to make up for the nonuniformity of beam, so that the radiant exitance on the radiated surface may become uniform. In this paper, we use a reflective microlens array to realize the laser beam shaping. By through of the practical optical path model established, the ray tracing is carried out and the simulation results for single-mode Gaussian beam with noise circumstance is provided. The analysis results show that the laser beam shaping under different inputs can be effectively realized by use of microlens array. All the energy is within the signal window, with a high energy efficiency of more than 90%; The measured surface has a better uniformity, and the uniformity is better than 99.5% at 150m.

  10. 3D shaping of electron beams using amplitude masks

    Energy Technology Data Exchange (ETDEWEB)

    Shiloh, Roy, E-mail: royshilo@post.tau.ac.il; Arie, Ady

    2017-06-15

    Highlights: • Electron beams are shaped in 3D with examples of curves and lattices. • Computer generated holograms are manifested as binary amplitude masks. • Applications in electron-optical particle trapping, manipulation, and synthesis. • Electron beam lithography fabrication scheme explained in detail. • Measurement paradigms of 3D shaped beams are discussed. - Abstract: Shaping the electron wavefunction in three dimensions may prove to be an indispensable tool for research involving atomic-sized particle trapping, manipulation, and synthesis. We utilize computer-generated holograms to sculpt electron wavefunctions in a standard transmission electron microscope in 3D, and demonstrate the formation of electron beams exhibiting high intensity along specific trajectories as well as shaping the beam into a 3D lattice of hot-spots. The concepts presented here are similar to those used in light optics for trapping and tweezing of particles, but at atomic scale resolutions.

  11. Mode Shape Analysis of Multiple Cracked Functionally Graded Timoshenko Beams

    Directory of Open Access Journals (Sweden)

    Tran Van Lien

    Full Text Available Abstract The present paper addresses free vibration of multiple cracked Timoshenko beams made of Functionally Graded Material (FGM. Cracks are modeled by rotational spring of stiffness calculated from the crack depth and material properties vary according to the power law throughout the beam thickness. Governing equations for free vibration of the beam are formulated with taking into account actual position of the neutral plane. The obtained frequency equation and mode shapes are used for analysis of the beam mode shapes in dependence on the material and crack parameters. Numerical results validate usefulness of the proposed herein theory and show that mode shapes are good indication for detecting multiple cracks in Timoshenko FGM beams.

  12. Beam shape coefficients of the most general focused Gaussian laser beam for light scattering applications

    International Nuclear Information System (INIS)

    Lock, James A.

    2013-01-01

    The vector wave equation for electromagnetic waves, when subject to a number of constraints corresponding to propagation of a monochromatic beam, reduces to a pair of inhomogeneous differential equations describing the transverse electric and transverse magnetic polarized beam components. These differential equations are solved analytically to obtain the most general focused Gaussian beam to order s 4 , where s is the beam confinement parameter, and various properties of the most general Gaussian beam are then discussed. The radial fields of the most general Gaussian beam are integrated to obtain the on-axis beam shape coefficients of the generalized Lorenz–Mie theory formalism of light scattering. The beam shape coefficients are then compared with those of the localized Gaussian beam model and the Davis–Barton fifth-order symmetrized beam. -- Highlights: ► Derive the differential equation for the most general Gaussian beam. ► Solve the differential equation for the most general Gaussian beam. ► Determine the properties of the most general Gaussian beam. ► Determine the beam shape coefficients of the most general Gaussian beam

  13. Beam Shaping for CARS Measurements in Turbulent Environments

    Science.gov (United States)

    Magnotti, Gaetano; Cutler, Andrew D.; Danehy, Paul M.

    2010-01-01

    This paper describes a new technique to mitigate the effect of beam steering on CARS measurements in turbulent, variable density environments. The new approach combines Planar BOXCARS phase-matching with elliptical shaping of one of the beams to generate a signal insensitive to beam steering, while keeping the same spatial resolution. Numerical and experimental results are provided to demonstrate the effectiveness of this approach. One set of experiments investigated the effect of beam shaping in the presence of a controlled and well quantified displacement of the beams at the focal plane. Another set of experiments, more qualitative, proved the effectiveness of the technique in the presence of severe beam steering due to turbulence.

  14. Generation of shape-invariant flat-top laser beams

    CSIR Research Space (South Africa)

    Ait-Ameur, K

    2015-02-01

    Full Text Available A great number of laser applications need in place of the usual Gaussian beam a flat-top intensity profile in the focal plane of a focusing lens. In general the transformation of the laser beam from the Gaussian to the flat-top shape is made by a...

  15. Semi-analytical solution to arbitrarily shaped beam scattering

    Science.gov (United States)

    Wang, Wenjie; Zhang, Huayong; Sun, Yufa

    2017-07-01

    Based on the field expansions in terms of appropriate spherical vector wave functions and the method of moments scheme, an exact semi-analytical solution to the scattering of an arbitrarily shaped beam is given. For incidence of a Gaussian beam, zero-order Bessel beam and Hertzian electric dipole radiation, numerical results of the normalized differential scattering cross section are presented to a spheroid and a circular cylinder of finite length, and the scattering properties are analyzed concisely.

  16. Diffractive beam shaping for enhanced laser polymer welding

    Science.gov (United States)

    Rauschenberger, J.; Vogler, D.; Raab, C.; Gubler, U.

    2015-03-01

    Laser welding of polymers increasingly finds application in a large number of industries such as medical technology, automotive, consumer electronics, textiles or packaging. More and more, it replaces other welding technologies for polymers, e. g. hot-plate, vibration or ultrasonic welding. At the same rate, demands on the quality of the weld, the flexibility of the production system and on processing speed have increased. Traditionally, diode lasers were employed for plastic welding with flat-top beam profiles. With the advent of fiber lasers with excellent beam quality, the possibility to modify and optimize the beam profile by beam-shaping elements has opened. Diffractive optical elements (DOE) can play a crucial role in optimizing the laser intensity profile towards the optimal M-shape beam for enhanced weld seam quality. We present results on significantly improved weld seam width constancy and enlarged process windows compared to Gaussian or flat-top beam profiles. Configurations in which the laser beam diameter and shape can be adapted and optimized without changing or aligning the laser, fiber-optic cable or optical head are shown.

  17. Beam shaping to provide round and square-shaped beams in optical systems of high-power lasers

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim

    2016-05-01

    Optical systems of modern high-power lasers require control of irradiance distribution: round or square-shaped flat-top or super-Gaussian irradiance profiles are optimum for amplification in MOPA lasers and for thermal load management while pumping of crystals of solid-state ultra-short pulse lasers to control heat and minimize its impact on the laser power and beam quality while maximizing overall laser efficiency, variable profiles are also important in irradiating of photocathode of Free Electron lasers (FEL). It is suggested to solve the task of irradiance re-distribution using field mapping refractive beam shapers like piShaper. The operational principle of these devices presumes transformation of laser beam intensity from Gaussian to flat-top one with high flatness of output wavefront, saving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with ultra-short pulse lasers having broad spectrum. Using the same piShaper device it is possible to realize beams with flat-top, inverse Gauss or super Gauss irradiance distribution by simple variation of input beam diameter, and the beam shape can be round or square with soft edges. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in optical systems of high-power lasers. Examples of real implementations and experimental results will be presented as well.

  18. Beam shaping as an enabler for new applications

    Science.gov (United States)

    Guertler, Yvonne; Kahmann, Max; Havrilla, David

    2017-02-01

    For many years, laser beam shaping has enabled users to achieve optimized process results as well as manage challenging applications. The latest advancements in industrial lasers and processing optics have taken this a step further as users are able to adapt the beam shape to meet specific application requirements in a very flexible way. TRUMPF has developed a wide range of experience in creating beam profiles at the work piece for optimized material processing. This technology is based on the physical model of wave optics and can be used with ultra short pulse lasers as well as multi-kW cw lasers. Basically, the beam shape can be adapted in all three dimensions in space, which allows maximum flexibility. Besides adaption of intensity profile, even multi-spot geometries can be produced. This approach is very cost efficient, because a standard laser source and (in the case of cw lasers) a standard fiber can be used without any special modifications. Based on this innovative beam shaping technology, TRUMPF has developed new and optimized processes. Two of the most recent application developments using these techniques are cutting glass and synthetic sapphire with ultra-short pulse lasers and enhanced brazing of hot dip zinc coated steel for automotive applications. Both developments lead to more efficient and flexible production processes, enabled by laser technology and open the door to new opportunities. They also indicate the potential of beam shaping techniques since they can be applied to both single-mode laser sources (TOP Cleave) and multi-mode laser sources (brazing).

  19. Engineering of automated assembly of beam-shaping optics

    Science.gov (United States)

    Haag, Sebastian; Sinhoff, Volker; Müller, Tobias; Brecher, Christian

    2014-03-01

    Beam-shaping is essential for any kind of laser application. Assembly technologies for beam-shaping subassemblies are subject to intense research and development activities and their technical feasibility has been proven in recent years while economic viability requires more efficient engineering tools for process planning and production ramp up of complex assembly tasks for micro-optical systems. The work presented in this paper aims for significant reduction of process development and production ramp up times for the automated assembly of micro-optical subassemblies for beam-collimation and beam-tilting. The approach proposed bridges the gap between the product development phase and the realization of automation control through integration of established software tools such as optics simulation and CAD modeling as well as through introduction of novel software tools and methods to efficiently describe active alignment strategies. The focus of the paper is put on the methodological approach regarding the engineering of assembly processes for beam-shaping micro-optics and the formal representation of assembly objectives similar to representation in mechanical assemblies. Main topic of the paper is the engineering methodology for active alignment processes based on the classification of optical functions for beam-shaping optics and corresponding standardized measurement setups including adaptable alignment algorithms. The concepts are applied to industrial use-cases: (1) integrated collimation module for fast- and slow-axis and (2) beam-tilting subassembly consisting of a fast-axis collimator and micro-lens array. The paper concludes with an overview of current limitations as well as an outlook on the next development steps considering adhesive bonding processes.

  20. Multi-focus beam shaping of high power multimode lasers

    Science.gov (United States)

    Laskin, Alexander; Volpp, Joerg; Laskin, Vadim; Ostrun, Aleksei

    2017-08-01

    Beam shaping of powerful multimode fiber lasers, fiber-coupled solid-state and diode lasers is of great importance for improvements of industrial laser applications. Welding, cladding with millimetre scale working spots benefit from "inverseGauss" intensity profiles; performance of thick metal sheet cutting, deep penetration welding can be enhanced when distributing the laser energy along the optical axis as more efficient usage of laser energy, higher edge quality and reduction of the heat affected zone can be achieved. Building of beam shaping optics for multimode lasers encounters physical limitations due to the low beam spatial coherence of multimode fiber-coupled lasers resulting in big Beam Parameter Products (BPP) or M² values. The laser radiation emerging from a multimode fiber presents a mixture of wavefronts. The fiber end can be considered as a light source which optical properties are intermediate between a Lambertian source and a single mode laser beam. Imaging of the fiber end, using a collimator and a focusing objective, is a robust and widely used beam delivery approach. Beam shaping solutions are suggested in form of optics combining fiber end imaging and geometrical separation of focused spots either perpendicular to or along the optical axis. Thus, energy of high power lasers is distributed among multiple foci. In order to provide reliable operation with multi-kW lasers and avoid damages the optics are designed as refractive elements with smooth optical surfaces. The paper presents descriptions of multi-focus optics as well as examples of intensity profile measurements of beam caustics and application results.

  1. A method for generating double-ring-shaped vector beams

    Science.gov (United States)

    Huan, Chen; Xiao-Hui, Ling; Zhi-Hong, Chen; Qian-Guang, Li; Hao, Lv; Hua-Qing, Yu; Xu-Nong, Yi

    2016-07-01

    We propose a method for generating double-ring-shaped vector beams. A step phase introduced by a spatial light modulator (SLM) first makes the incident laser beam have a nodal cycle. This phase is dynamic in nature because it depends on the optical length. Then a Pancharatnam-Berry phase (PBP) optical element is used to manipulate the local polarization of the optical field by modulating the geometric phase. The experimental results show that this scheme can effectively create double-ring-shaped vector beams. It provides much greater flexibility to manipulate the phase and polarization by simultaneously modulating the dynamic and the geometric phases. Project supported by the National Natural Science Foundation of China (Grant No. 11547017), the Hubei Engineering University Research Foundation, China (Grant No. z2014001), and the Natural Science Foundation of Hubei Province, China (Grant No. 2014CFB578).

  2. Beam-based alignment of C-shaped quadrupole magnets

    International Nuclear Information System (INIS)

    Portmann, G.; Robin, D.

    1998-06-01

    Many storage rings have implemented a method of finding the positional offset between the electrical center of the beam position monitors (BPM) and the magnetic center of the adjacent quadrupole magnets. The algorithm for accomplishing this is usually based on modulating the current in the quadrupole magnet and finding the beam position that minimizes the orbit perturbation. When the quadrupole magnet is C-shaped, as it is for many light sources, the modulation method can produce an erroneous measurement of the magnetic center in the horizontal plane. When the current in a C-shaped quadrupole is changed, there is an additional dipole component in the vertical field. Due to nonlinearities in the hysteresis cycle of the C-magnet geometry, the beam-based alignment technique at the Advanced Light Source (ALS) deviated horizontally by .5 mm from the actual magnetic center. By modifying the technique, the offsets were measured to an accuracy of better than 50 microm

  3. The characterization of beam profile by modification of electrode shape

    International Nuclear Information System (INIS)

    Lee, Chan Young; Lee, Jae Sang

    2010-01-01

    Ion sources have been used for variety of industrial application over the past few decades and our research group has been studied about high current and large dimension ion source to meet the requirement from beam user. For a mass production in industry, a wide beam divergence and a beam profile of a broadly Gaussian shape is very needed. Generally, the production process like roll-to-roll or in-line system is need one-meter in diameter, ±5% in uniformity. Therefore it is difficult to apply with present system like 0.3-meter in diameter, ±20% in uniformity and needed new type ion source. In this study, it is approached with modification of electrode grid shape without fabrication of new type ion source. We modified from parallel type to hemispherical type electrode grid to secure large dimension ion beam and were discussed with respect to beam profile calculated with IGUN code simulation. Also, we identified beam profile before and after modification of electrode grid system(cathode, Acelldecel grid) with measurement of faraday cup

  4. Gaussian beam profile shaping apparatus, method therefore and evaluation thereof

    International Nuclear Information System (INIS)

    Dickey, F.M.; Holswade, S.C.; Romero, L.A.

    1999-01-01

    A method and apparatus maps a Gaussian beam into a beam with a uniform irradiance profile by exploiting the Fourier transform properties of lenses. A phase element imparts a design phase onto an input beam and the output optical field from a lens is then the Fourier transform of the input beam and the phase function from the phase element. The phase element is selected in accordance with a dimensionless parameter which is dependent upon the radius of the incoming beam, the desired spot shape, the focal length of the lens and the wavelength of the input beam. This dimensionless parameter can also be used to evaluate the quality of a system. In order to control the radius of the incoming beam, optics such as a telescope can be employed. The size of the target spot and the focal length can be altered by exchanging the transform lens, but the dimensionless parameter will remain the same. The quality of the system, and hence the value of the dimensionless parameter, can be altered by exchanging the phase element. The dimensionless parameter provides design guidance, system evaluation, and indication as to how to improve a given system. 27 figs

  5. Beam shaping of light sources using circular photonic crystal funnel

    Science.gov (United States)

    Kumar, Mrityunjay; Kumar, Mithun; Dinesh Kumar, V.

    2012-10-01

    A novel two-dimensional circular photonic crystal (CPC) structure with a sectorial opening for shaping the beam of light sources was designed and investigated. When combined with light sources, the structure acts like an antenna emitting a directional beam which could be advantageously used in several nanophotonic applications. Using the two-dimensional finite-difference time-domain (2D FDTD) method, we examined the effects of geometrical parameters of the structure on the directional and transmission properties of emitted radiation. Further, we examined the transmitting and receiving properties of a pair of identical structures as a function of distance between them.

  6. Workshop on automated beam steering and shaping (ABS). Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Lindroos, M [ed.

    1999-09-10

    A workshop on Automated Beam Steering and Shaping (ABS) was held at CERN in December 1998. This was the first workshop dedicated to this subject. The workshop had two major goals: to review the present status of ABS algorithms and systems around the world and to create a worldwide ABS community. These proceedings contain summary reports from all sessions, contributions from several presentations held at the workshop, and a complete set of abstracts for all presentations. (orig.)

  7. Workshop on automated beam steering and shaping (ABS). Proceedings

    International Nuclear Information System (INIS)

    Lindroos, M.

    1999-01-01

    A workshop on Automated Beam Steering and Shaping (ABS) was held at CERN in December 1998. This was the first workshop dedicated to this subject. The workshop had two major goals: to review the present status of ABS algorithms and systems around the world and to create a worldwide ABS community. These proceedings contain summary reports from all sessions, contributions from several presentations held at the workshop, and a complete set of abstracts for all presentations. (orig.)

  8. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    Science.gov (United States)

    Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; Kiefer, Jacob; Bazarov, Ivan

    2015-02-01

    The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  9. Studies of pear-shaped nuclei using accelerated radioactive beams

    CERN Document Server

    Gaffney, L P; Scheck, M; Hayes, A B; Wenander, F; Albers, M; Bastin, B; Bauer, C; Blazhev, A; Bonig, S; Bree, N; Cederkall, J; Chupp, T; Cline, D; Cocolios, T E; Davinson, T; DeWitte, H; Diriken, J; Grahn, T; Herzan, A; Huyse, M; Jenkins, D G; Joss, D T; Kesteloot, N; Konki, J; Kowalczyk, M; Kroll, Th; Kwan, E; Lutter, R; Moschner, K; Napiorkowski, P; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Reynders, K; Rigby, S V; Robledo, L M; Rudigier, M; Sambi, S; Seidlitz, M; Siebeck, B; Stora, T; Thoele, P; Van Duppen, P; Vermeulen, M J; von Schmid, M; Voulot, D; Warr, N; Wimmer, K; Wrzosek-Lipska, K; Wu, C Y; Zielinska, M

    2013-01-01

    There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on and $^{224}$Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental...

  10. Beam shaping for conformal fractionated stereotactic radiotherapy: a modeling study

    International Nuclear Information System (INIS)

    Hacker, Fred L.; Kooy, Hanne M.; Bellerive, Marc R.; Killoran, Joseph H.; Leber, Zachary H.; Shrieve, Dennis C.; Tarbell, Nancy J.; Loeffler, Jay S.

    1997-01-01

    Purpose: The patient population treated with fractionated stereotactic radiotherapy (SRT) is significantly different than that treated with stereotactic radiosurgery (SRS). Generally, lesions treated with SRT are larger, less spherical, and located within critical regions of the central nervous system; hence, they offer new challenges to the treatment planner. Here a simple, cost effective, beam shaping system has been evaluated relative to both circular collimators and an ideal dynamically conforming system for effectiveness in providing conformal therapy for these lesions. Methods and Materials: We have modeled a simple system for conformal arc therapy using four independent jaws. The jaw positions and collimator angle are changed between arcs but held fixed for the duration of each arc. Eleven previously treated SRT cases have been replanned using this system. The rectangular jaw plans were then compared to the original treatment plans which used circular collimators. The plans were evaluated with respect to tissue sparing at 100%, 80%, 50%, and 20% of the prescription dose. A plan was also done for each tumor in which the beam aperture was continuously conformed to the beams eye view projection of the tumor. This was used as an ideal standard for conformal therapy in the absence of fluence modulation. Results: For tumors with a maximum extent of over 3.5 cm the rectangular jaw plans reduced the mean volume of healthy tissue involved at the prescription dose by 57% relative to the circular collimator plans. The ideal conformal plans offered no significant further improvement at the prescription dose. The relative advantage of the rectangular jaw plans decreased at lower isodoses so that at 20% of the prescription dose tissue involvement for the rectangular jaw plans was equivalent to that for the circular collimator plans. At these isodoses the ideal conformal plans gave substantially better tissue sparing. Conclusion: A simple and economical field shaping

  11. Determination of the meniscus shape of a negative ion beam from an experimentally obtained beam profile

    Science.gov (United States)

    Ichikawa, M.; Kojima, A.; Chitarin, G.; Agostinetti, P.; Aprile, D.; Baltador, C.; Barbisan, M.; Delogu, R.; Hiratsuka, J.; Marconato, N.; Nishikiori, R.; Pimazzoni, A.; Sartori, E.; Serianni, G.; Tobari, H.; Umeda, N.; Veltri, P.; Watanabe, K.; Yoshida, M.; Antoni, V.; Kashiwagi, M.

    2017-08-01

    In order to understand the physics mechanism of a negative ion extraction in negative ion sources, an emission surface of the negative ions around an aperture at a plasma grid, so-called a meniscus, has been analyzed by an inverse calculation of the negative ion trajectory in a two dimensional beam analysis code. In this method, the meniscus is defined as the final position of the negative ion trajectories which are inversely calculated from the measured beam profile to the plasma grid. In a case of the volume-produced negative ions, the calculated meniscus by the inverse calculation was similar to that obtained in conventional beam simulation codes for positive ion extractions such as BEAMORBT and SLACCAD. The negative ion current density was uniform along the meniscus. This indicates that the negative ions produced in the plasma are transported to the plasma grid uniformly as considered in the transportation of the positive ions. However, in a surface production case of negative ions, where the negative ions are generated near the plasma grid with lower work function by seeding cesium, the current density in the peripheral region of the meniscus close to the plasma grid surface was estimated to be 2 times larger than the center region, which suggested that the extraction process of the surface-produced negative ions was much different with that for the positive ions. Because this non-uniform profile of the current density made the meniscus shape strongly concave, the beam extracted from the peripheral region could have a large divergence angle, which might be one of origins of so-called beam halo. This is the first results of the determination of the meniscus based on the experiment, which is useful to improve the prediction of the meniscus shape and heat loads based on the beam trajectories including beam halo.

  12. Extension of Ko Straight-Beam Displacement Theory to Deformed Shape Predictions of Slender Curved Structures

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2011-01-01

    The Ko displacement theory originally developed for shape predictions of straight beams is extended to shape predictions of curved beams. The surface strains needed for shape predictions were analytically generated from finite-element nodal stress outputs. With the aid of finite-element displacement outputs, mathematical functional forms for curvature-effect correction terms are established and incorporated into straight-beam deflection equations for shape predictions of both cantilever and two-point supported curved beams. The newly established deflection equations for cantilever curved beams could provide quite accurate shape predictions for different cantilever curved beams, including the quarter-circle cantilever beam. Furthermore, the newly formulated deflection equations for two-point supported curved beams could provide accurate shape predictions for a range of two-point supported curved beams, including the full-circular ring. Accuracy of the newly developed curved-beam deflection equations is validated through shape prediction analysis of curved beams embedded in the windward shallow spherical shell of a generic crew exploration vehicle. A single-point collocation method for optimization of shape predictions is discussed in detail

  13. Soft apertures to shape high-power laser beams

    International Nuclear Information System (INIS)

    Lukishova, S.G.; Pashinin, P.P.; Batygov, S.K.; Terentiev, B.M.

    1989-01-01

    Soft or apodized apertures with smooth decreasing from center to edges transmission profiles are used in laser physics for beam shaping. This paper gives the results of the studies of four types of these units for UV, visible and IR lasers. They are made of glasses or crystals with the use of one of the following technologies: absorption induced by ionizing radiation; photodestruction of color centers or photooxidation of impurities ions; additive coloration; frustrated total internal reflection. The special feature of such apertures is their high optical damage resistance under the irradiation of single-pulse laser radiation. They are approximately 3-50 mm in diameter by the methods of making them give the possibility to create near-Gaussian and flat-top beams with dimensions less than 1 mm and larger than 200 mm. The results of using them in high-power single-pulse lasers are presented. Damage thresholds of these apertures in such types of lasers have been defined

  14. Simultaneous beam sampling and aperture shape optimization for SPORT

    International Nuclear Information System (INIS)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei; Ye, Yinyu

    2015-01-01

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  15. Simultaneous beam sampling and aperture shape optimization for SPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei, E-mail: Lei@stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Ye, Yinyu [Department of Management Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-02-15

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  16. Simultaneous beam sampling and aperture shape optimization for SPORT.

    Science.gov (United States)

    Zarepisheh, Masoud; Li, Ruijiang; Ye, Yinyu; Xing, Lei

    2015-02-01

    Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and neck and a prostate case

  17. Ion beam system for implanting industrial products of various shapes

    International Nuclear Information System (INIS)

    Denholm, A.S.; Wittkower, A.

    1985-01-01

    Implantation of metals and ceramics with ions of nitrogen and other species has improved surface properties such as friction, wear and corrosion in numerous industrial applications. Zymet has built a production machine to take advantage of this process which can implant a 2 x 10 17 ions/cm 2 dose of nitrogen ions into a 20 cm x 20 cm area in about 30 min using a 100 keV beam. Treatment is accomplished by mounting the product on a cooled, tiltable, turntable which rotates continuously, or is indexed in 15 0 steps to expose different surfaces in fixed position. Product cooling is accomplished by using a chilled eutectic metal to mount and grip the variously shaped objects. A high voltage supply capable of 10 mA at 100 kV is used, and the equipment is microcomputer controlled via serial light links. All important machine parameters are presented in sequenced displays on a CRT. Uniformity of treatment and accumulated dose are monitored by a Faraday cup system which provides the microprocessor with data for display of time to completion on the process screen. For routine implants the operator requires only two buttons; one for chamber vacuum control, and the other for process start and stop. (orig.)

  18. Annular beam shaping system for advanced 3D laser brazing

    Science.gov (United States)

    Pütsch, Oliver; Stollenwerk, Jochen; Kogel-Hollacher, Markus; Traub, Martin

    2012-10-01

    As laser brazing benefits from advantages such as smooth joints and small heat-affected zones, it has become established as a joining technology that is widely used in the automotive industry. With the processing of complex-shaped geometries, recent developed brazing heads suffer, however, from the need for continuous reorientation of the optical system and/or limited accessibility due to lateral wire feeding. This motivates the development of a laser brazing head with coaxial wire feeding and enhanced functionality. An optical system is designed that allows to generate an annular intensity distribution in the working zone. The utilization of complex optical components avoids obscuration of the optical path by the wire feeding. The new design overcomes the disadvantages of the state-of-the-art brazing heads with lateral wire feeding and benefits from the independence of direction while processing complex geometries. To increase the robustness of the brazing process, the beam path also includes a seam tracking system, leading to a more challenging design of the whole optical train. This paper mainly discusses the concept and the optical design of the coaxial brazing head, and also presents the results obtained with a prototype and selected application results.

  19. 21 CFR 892.5710 - Radiation therapy beam-shaping block.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiation therapy beam-shaping block. 892.5710 Section 892.5710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... block. (a) Identification. A radiation therapy beam-shaping block is a device made of a highly...

  20. Alternative modes for optical trapping and manipulation using counter-propagating shaped beams

    International Nuclear Information System (INIS)

    Palima, D; Tauro, S; Glückstad, J; Lindballe, T B; Kristensen, M V; Stapelfeldt, H; Keiding, S R

    2011-01-01

    Counter-propagating beams have enabled the first stable three-dimensional optical trapping of microparticles and this procedure has been enhanced and developed over the years to achieve independent and interactive manipulation of multiple particles. In this work, we analyse counter-propagating shaped-beam traps that depart from the conventional geometry based on symmetric, coaxial counter-propagating beams. We show that projecting shaped beams with separation distances previously considered axially unstable can, in fact, enhance the axial and transverse trapping stiffnesses. We also show that deviating from using perfectly counter-propagating beams to use oblique beams can improve the axial stability of the traps and improve the axial trapping stiffness. These alternative geometries can be particularly useful for handling larger particles. These results hint at a rich potential for light shaping for optical trapping and manipulation using patterned counter-propagating beams, which still remains to be fully tapped

  1. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    Directory of Open Access Journals (Sweden)

    Jared Maxson

    2015-02-01

    Full Text Available The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  2. A line scanned light-sheet microscope with phase shaped self-reconstructing beams.

    Science.gov (United States)

    Fahrbach, Florian O; Rohrbach, Alexander

    2010-11-08

    We recently demonstrated that Microscopy with Self-Reconstructing Beams (MISERB) increases both image quality and penetration depth of illumination beams in strongly scattering media. Based on the concept of line scanned light-sheet microscopy, we present an add-on module to a standard inverted microscope using a scanned beam that is shaped in phase and amplitude by a spatial light modulator. We explain technical details of the setup as well as of the holograms for the creation, positioning and scaling of static light-sheets, Gaussian beams and Bessel beams. The comparison of images from identical sample areas illuminated by different beams allows a precise assessment of the interconnection between beam shape and image quality. The superior propagation ability of Bessel beams through inhomogeneous media is demonstrated by measurements on various scattering media.

  3. Electron Beam Energy Compensation by Controlling RF Pulse Shape

    CERN Document Server

    Kii, T; Kusukame, K; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.

  4. Parameters affecting profile shape of a high energy low current thin ion beam. Vol. 2

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Salam, F W; Moustafa, O A; El-Khabeary, H [Accelerators Department, Nuclear Research Center, Atomic Energy Authority, Cairo, (Egypt)

    1996-03-01

    The shape of the profile of a high energy, low current beam of finite length has beam investigated. The beam profile shape depends on the initial beam radius, beam perveance, atomic mass number, charge state of ions, and beam length. These parameters can affect the relation between the initial beam radius and the corresponding final one. An optimum initial beam radius corresponding to minimum final beam at the target has been formulated and the relation between them is deduced taking account of the space charge effect. The minimum beam radius at the target was found to be equal to 2.3 of the optimum initial radius. It is concluded that in order to obtain a small beam radius at a target placed at a finite distance from an ion source, a beam of a low perveance, low atomic mass number and high number of electronic charge is required. This is an important detection for micro machining applications using the oscillating electron ion source which produces nearly paraxial thin beam of low perveance. 12 figs.

  5. Sagagd method for the beam shaping of uniform illumination

    International Nuclear Information System (INIS)

    Li Yongping; Chen Dewei; Wang Wei

    2002-01-01

    The simulated annealing algorithm, the genetic and the gradient descent algorithm are retrospectively and successfully amalgamated to optimal design of pure phase element for uniform beams. The process of this method is divided into three steps, first the energy enhancement of the main lobe, then the process to make the top of the main lobe to be smooth and the fringe to be steep, at last the full optimization beam. After these three steps of optimization, the beam is good enough to be applied to ICF

  6. Comparison of infrared laser beam shaping by diffractive and refractive methods

    CSIR Research Space (South Africa)

    Forbes, A

    2005-08-01

    Full Text Available Infra-red laser beam shaping has the inherent difficulty that simple ray tracing methods often yield anomalous results, due primarily to the propagation effects at longer wavelengths. Techniques based on diffraction theory have been developed...

  7. Design a freeform microlens array module for any arbitrary-shape collimated beam shaping and color mixing

    Science.gov (United States)

    Chen, Enguo; Wu, Rengmao; Guo, Tailiang

    2014-06-01

    Collimated beam shaping with freeform surface usually employs a predefined mapping to tailor one or multiple freeform surfaces. Limitation on those designs is that the source, the freeform optics and the target are in fixed one-to-one correspondence with each other. To overcome this drawback, this paper presents a kind of freeform microlens array module integrated with an ultra-thin freeform microlens array and a condenser lens to reshape any arbitrary-shape collimated beam into a prescribed uniform rectangular illumination and achieve color mixing. The design theory is explicitly given, and some key issues are addressed. Several different application examples are given, and the target is obtained with high uniformity and energy efficiency. This freeform microlens array module, which shows better flexibility and practicality than the regular designs, can be used not only to reshape any arbitrary-shape collimated beam (or a collimated beam integrated with several sub-collimated beams), but also most importantly to achieve color mixing. With excellent optical performance and ultra-compact volume, this optical module together with the design theory can be further introduced into other applications and will have a huge market potential in the near future.

  8. Beam shaping optics to enhance performance of interferometry techniques in grating manufacture

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2018-02-01

    Improving of industrial holographic and interferometry techniques is of great importance in interference lithography, computer-generated holography, holographic data storage, interferometry recording of Bragg gratings as well as gratings of various types in semiconductor industry. Performance of mentioned techniques is essentially enhanced by providing a light beam with flat phase front and flat-top irradiance distribution. Therefore, transformation of Gaussian distribution of a TEM00 laser to flat-top (top hat, uniform) distribution is an important optical task. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. As a solution it is suggested to apply refractive field mapping beam shaping optics πShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. High optical quality of resulting flat-top beam allows applying additional optical components to build various imaging optical systems for variation of beam size and shape to fulfil requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holography and laser interference lithography. Examples of real implementations and experimental results will be presented as well.

  9. Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

    International Nuclear Information System (INIS)

    Liu, X; Lamarque, F; Doré, E; Pouille, P

    2015-01-01

    This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements. (paper)

  10. Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

    Science.gov (United States)

    Liu, X.; Lamarque, F.; Doré, E.; Pouille, P.

    2015-07-01

    This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements.

  11. Beam shape coefficients calculation for an elliptical Gaussian beam with 1-dimensional quadrature and localized approximation methods

    Science.gov (United States)

    Wang, Wei; Shen, Jianqi

    2018-06-01

    The use of a shaped beam for applications relying on light scattering depends much on the ability to evaluate the beam shape coefficients (BSC) effectively. Numerical techniques for evaluating the BSCs of a shaped beam, such as the quadrature, the localized approximation (LA), the integral localized approximation (ILA) methods, have been developed within the framework of generalized Lorenz-Mie theory (GLMT). The quadrature methods usually employ the 2-/3-dimensional integrations. In this work, the expressions of the BSCs for an elliptical Gaussian beam (EGB) are simplified into the 1-dimensional integral so as to speed up the numerical computation. Numerical results of BSCs are used to reconstruct the beam field and the fidelity of the reconstructed field to the given beam field is estimated. It is demonstrated that the proposed method is much faster than the 2-dimensional integrations and it can acquire more accurate results than the LA method. Limitations of the quadrature method and also the LA method in the numerical calculation are analyzed in detail.

  12. Photoinjector beam quality improvement by shaping the wavefront of a drive laser with oblique incidence

    International Nuclear Information System (INIS)

    He Zhigang; Wang Xiaohui; Jia Qika

    2012-01-01

    To increase the quantum efficiency (QE) of a copper photocathode and reduce the thermal emittance of an electron beam, a drive laser with oblique incidence was adopted in a BNL type photocathode rf gun. The disadvantageous effects on the beam quality caused by oblique incidence were analyzed qualitatively. A simple way to solve the problems through wavefront shaping was introduced and the beam quality was improved. (authors)

  13. Nonlinear propagation of an elliptically shaped Gaussian laser beam in an overdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nayyar, V P; Soni, V S [Punjabi Univ., Patiala (India). Dept. of Physics

    1979-04-01

    The self-focusing and self defocusing of an elliptically shaped high power laser beam in an extradense plasma is discussed. On account of the ponderomotive force induced by the spatial variation of irradiance in the transverse plane, an electron density gradient is created in the overdense plasma where the beam can penetrate. Self-focusing of the beam in the x and y directions for different critical powers has been extensively studied.

  14. Feedback control of laser welding based on frequency analysis of light emissions and adaptive beam shaping

    Czech Academy of Sciences Publication Activity Database

    Mrňa, Libor; Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr

    2012-01-01

    Roč. 39, NOV (2012), s. 784-791 ISSN 1875-3892. [LANE 2012. Laser Assisted Net Shape Engineering /7./ International Conference on Photonic Technologies. Fürth, 12.11.2012-15.12.2012] Institutional support: RVO:68081731 Keywords : laser welding * feedback control * frequency analysis * adaptive beam shaping Subject RIV: BH - Optics, Masers, Lasers

  15. Shape optimization and sensitivity of compliant beams for prescribed load-displacement response

    NARCIS (Netherlands)

    Radaelli, G.; Herder, J.L.

    2016-01-01

    This paper presents the shape optimization of a compliant beam for prescribed load-displacements response. The analysis of the design is based on the isogeometric analysis framework for an enhanced fidelity between designed and analysed shape. The sensitivities used for an improved optimization

  16. Laser beam shaping for studying thermally induced damage

    CSIR Research Space (South Africa)

    Masina, BN

    2011-08-01

    Full Text Available into a flat-top beam profile by using a diffractive optical element as a phase element in conjunction with a Fourier transforming lens. In this paper, they have successfully demonstrated temperature profiles across the diamond tool surface using two laser...

  17. Woven type smart soft composite beam with in-plane shape retention

    International Nuclear Information System (INIS)

    Wu, Renzhe; Han, Min-Woo; Lee, Gil-Yong; Ahn, Sung-Hoon

    2013-01-01

    Shape memory alloy (SMA) wire embedded composites (SMAECs) are widely used as morphing structures in small-size and high-output systems. However, conventional SMAECs cannot keep deformed shapes without additional energy. In this paper, a new kind of smart structure named the woven type smart soft composite (SSC) beam is introduced, which is not only capable of morphing, but also maintaining its deformed shape without additional energy. The woven type SSC beam consists of two parts: woven wires and matrix. The selected woven wires are nitinol (Ni–Ti) SMA wires and glass fibers, while the matrix part is polydimethylsiloxane (PDMS). In order to evaluate the performance of the woven type SSC beam in areas such as in-plane deformation, blocking force and repeatability, a beam-shape specimen is prepared of size 100 mm (length) × 8 mm (width) ×3 mm (thickness). The fabricated SSC beam achieved 21 mm deformation and 16 mm shape retention. Blocking force was measured using a dynamometer, and was about 60 mN. In the repeatability test, it recovered almost the same position when its cooling time was 90 s more. Consequently, the woven type SSC beam can be applied to bio-mimicking, soft morphing actuators, consuming less energy than traditional SMAECs. (paper)

  18. Design of measurement equipment for high power laser beam shapes

    DEFF Research Database (Denmark)

    Hansen, K. S.; Olsen, F. O.; Kristiansen, Morten

    2013-01-01

    To analyse advanced high power beam patterns, a method, which is capable of analysing the intensity distribution in 3D is needed. Further a measuring of scattered light in the same system is preferred. This requires a high signal to noise ratio. Such a system can be realised by a CCD-chip impleme...... by a commercial product has been done. The realised system might suffer from some thermal drift at high power; future work is to clarify this....

  19. Behaviour of smart reinforced concrete beam with super elastic shape memory alloy subjected to monotonic loading

    Science.gov (United States)

    Hamid, Nubailah Abd; Ibrahim, Azmi; Adnan, Azlan; Ismail, Muhammad Hussain

    2018-05-01

    This paper discusses the superelastic behavior of shape memory alloy, NiTi when used as reinforcement in concrete beams. The ability of NiTi to recover and reduce permanent deformations of concrete beams was investigated. Small-scale concrete beams, with NiTi reinforcement were experimentally investigated under monotonic loads. The behaviour of simply supported reinforced concrete (RC) beams hybrid with NiTi rebars and the control beam subject to monotonic loads were experimentally investigated. This paper is to highlight the ability of the SMA bars to recover and reduce permanent deformations of concrete flexural members. The size of the control beam is 125 mm × 270 mm × 1000 mm with 3 numbers of 12 mm diameter bars as main reinforcement for compression and 3 numbers of 12 mm bars as tension or hanger bars while 6 mm diameter at 100 mm c/c used as shear reinforcement bars for control beam respectively. While, the minimal provision of 200mm using the 12.7mm of superelastic Shape Memory Alloys were employed to replace the steel rebar at the critical region of the beam. In conclusion, the contribution of the SMA bar in combination with high-strength steel to the conventional reinforcement showed that the SMA beam has exhibited an improve performance in term of better crack recovery and deformation. Therefore the usage of hybrid NiTi with the steel can substantially diminish the risk of the earthquake and also can reduce the associated cost aftermath.

  20. Laser Beam delivering and shaping device for transfer of organic film

    International Nuclear Information System (INIS)

    Lee, Kangin; Kwon, Jin Hyuk; Yi, Jonghoon

    2008-01-01

    The laser based organic material transfer methods are developed by several groups for OLED (organic light emitting diode)fabrication. Well developed laser based methods are LITI (Laser Induced Thermal Imaging)and LIPS (Laser Induced Pattern wise Sublimation). These methods are proved to be suitable for large OLED panel fabrication. At an early stage of development, TEM"00"mode Nd:YAG laser was used for pattering organic material. The focused focused Nd:YAG laser beam generated heat in the film and the heat caused expansion of organic material coated layer. The organic film on the layer is transferred to the display panel due to pressure exerted on the display panel by the layer. Recently developed system prefers to employ a diode laser with wavelength of 800nm. Diode laser is cheaper and smaller photon source compared with the Nd:YAG laser. In this work, we use Nd doped fiber laser (wavelength=1070nm, power=10W)because the laser has stable output and well defined Gaussian beam profile compared with diode laser. We also employed fiber coupled diode laser (808nm)because it also has well defined beam distribution. In laser methods, spatially shaped beam is required for clean and sharp transfer. There are several methods for the beam shaping such as aspheric lens, diffractive optical elements, and micro lens array etc. We found that Gaussian beam can be shaped to a square hat like beam just by using simple commercial spherical lens set

  1. New vistas in refractive laser beam shaping with an analytic design approach

    Science.gov (United States)

    Duerr, Fabian; Thienpont, Hugo

    2014-05-01

    Many commercial, medical and scientific applications of the laser have been developed since its invention. Some of these applications require a specific beam irradiance distribution to ensure optimal performance. Often, it is possible to apply geometrical methods to design laser beam shapers. This common design approach is based on the ray mapping between the input plane and the output beam. Geometric ray mapping designs with two plano-aspheric lenses have been thoroughly studied in the past. Even though analytic expressions for various ray mapping functions do exist, the surface profiles of the lenses are still calculated numerically. In this work, we present an alternative novel design approach that allows direct calculation of the rotational symmetric lens profiles described by analytic functions. Starting from the example of a basic beam expander, a set of functional differential equations is derived from Fermat's principle. This formalism allows calculating the exact lens profiles described by Taylor series coefficients up to very high orders. To demonstrate the versatility of this new approach, two further cases are solved: a Gaussian to at-top irradiance beam shaping system, and a beam shaping system that generates a more complex dark-hollow Gaussian (donut-like) irradiance profile with zero intensity in the on-axis region. The presented ray tracing results confirm the high accuracy of all calculated solutions and indicate the potential of this design approach for refractive beam shaping applications.

  2. Spectrum shaping of accelerator-based neutron beams for BNCT

    CERN Document Server

    Montagnini, B; Esposito, J; Giusti, V; Mattioda, F; Varone, R

    2002-01-01

    We describe Monte Carlo simulations of three facilities for the production of epithermal neutrons for Boron Neutron Capture Therapy (BNCT) and examine general aspects and problems of designing the spectrum-shaping assemblies to be used with these neutron sources. The first facility is based on an accelerator-driven low-power subcritical reactor, operating as a neutron amplifier. The other two facilities have no amplifier and rely entirely on their primary sources, a D-T fusion reaction device and a conventional 2.5 MeV proton accelerator with a Li target, respectively.

  3. 3D-printed phase waveplates for THz beam shaping

    Science.gov (United States)

    Gospodaric, J.; Kuzmenko, A.; Pimenov, Anna; Huber, C.; Suess, D.; Rotter, S.; Pimenov, A.

    2018-05-01

    The advancement of 3D-printing opens up a new way of constructing affordable custom terahertz (THz) components due to suitable printing resolution and THz transparency of polymer materials. We present a way of calculating, designing, and fabricating a THz waveplate that phase-modulates an incident THz beam (λ0 = 2.14 mm) in order to create a predefined intensity profile of the optical wavefront on a distant image plane. Our calculations were performed for two distinct target intensities with the use of a modified Gerchberg-Saxton algorithm. The resulting phase-modulating profiles were used to model the polylactide elements, which were printed out with a commercially available 3D-printer. The results were tested in a THz experimental setup equipped with a scanning option, and they showed good agreement with theoretical predictions.

  4. Precision shape modification of nanodevices with a low-energy electron beam

    Science.gov (United States)

    Zettl, Alex; Yuzvinsky, Thomas David; Fennimore, Adam

    2010-03-09

    Methods of shape modifying a nanodevice by contacting it with a low-energy focused electron beam are disclosed here. In one embodiment, a nanodevice may be permanently reformed to a different geometry through an application of a deforming force and a low-energy focused electron beam. With the addition of an assist gas, material may be removed from the nanodevice through application of the low-energy focused electron beam. The independent methods of shape modification and material removal may be used either individually or simultaneously. Precision cuts with accuracies as high as 10 nm may be achieved through the use of precision low-energy Scanning Electron Microscope scan beams. These methods may be used in an automated system to produce nanodevices of very precise dimensions. These methods may be used to produce nanodevices of carbon-based, silicon-based, or other compositions by varying the assist gas.

  5. Actuator Location and Voltages Optimization for Shape Control of Smart Beams Using Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Georgios E. Stavroulakis

    2013-10-01

    Full Text Available This paper presents a numerical study on optimal voltages and optimal placement of piezoelectric actuators for shape control of beam structures. A finite element model, based on Timoshenko beam theory, is developed to characterize the behavior of the structure and the actuators. This model accounted for the electromechanical coupling in the entire beam structure, due to the fact that the piezoelectric layers are treated as constituent parts of the entire structural system. A hybrid scheme is presented based on great deluge and genetic algorithm. The hybrid algorithm is implemented to calculate the optimal locations and optimal values of voltages, applied to the piezoelectric actuators glued in the structure, which minimize the error between the achieved and the desired shape. Results from numerical simulations demonstrate the capabilities and efficiency of the developed optimization algorithm in both clamped−free and clamped−clamped beam problems are presented.

  6. Load carrying capacity of RCC beams by replacing steel reinforcement bars with shape memory alloy bars

    Science.gov (United States)

    Bajoria, Kamal M.; Kaduskar, Shreya S.

    2016-04-01

    In this paper the structural behavior of reinforced concrete (RC) beams with smart rebars under two point loading system has been numerically studied, using Finite Element Method. The material used in this study is Super-elastic Shape Memory Alloys (SE SMAs) which contains nickel and titanium. In this study, different quantities of steel and SMA rebars have been used for reinforcement and the behavior of these models under two point bending loading system is studied. A comparison of load carrying capacity for the model between steel reinforced concrete beam and the beam reinforced with S.M.A and steel are performed. The results show that RC beams reinforced with combination of shape memory alloy and steel show better performance.

  7. Shape optimization of a Timoshenko beam together with an elastic foundation

    Directory of Open Access Journals (Sweden)

    Machalová J.

    2010-12-01

    Full Text Available In this article we are going first to aim at the variational ormulation of the bending problem for the Timoshenko beam model. Afterwards we will extend this problem to the Timoshenko beam resting on the Winkler foundation, which is firmly connected with the beam. Hereafter a shape optimization for the aforementioned problems is presented. The state problem is here represented by the system of two ordinary differential equations of the second order. The optimization problem is given as a minimization of the so-called compliance functional on the set of all admissible design variables. For our purpose as the design variable we will select the beam thickness. Shape optimization problems have attracted the interest of many applied mathematicians and engineers. The objective of this article is to present a solution method for one of these problems and its demonstration by examples.

  8. Spectral and spatial shaping of a laser-produced ion beam for radiation-biology experiments

    Directory of Open Access Journals (Sweden)

    L. Pommarel

    2017-03-01

    Full Text Available The study of radiation biology on laser-based accelerators is most interesting due to the unique irradiation conditions they can produce, in terms of peak current and duration of the irradiation. In this paper we present the implementation of a beam transport system to transport and shape the proton beam generated by laser-target interaction for in vitro irradiation of biological samples. A set of four permanent magnet quadrupoles is used to transport and focus the beam, efficiently shaping the spectrum and providing a large and relatively uniform irradiation surface. Real time, absolutely calibrated, dosimetry is installed on the beam line, to enable shot-to-shot control of dose deposition in the irradiated volume. Preliminary results of cell sample irradiation are presented to validate the robustness of the full system.

  9. Shaping the electron beams with submicrosecond pulse duration in sources and electron accelerators with plasma emitters

    CERN Document Server

    Gushenets, V I

    2001-01-01

    One studies the techniques in use to shape submicrosecond electron beams and the physical processes associated with extraction of electrons from plasma in plasma emitters. Plasma emitter base sources and accelerators enable to generate pulse beams with currents varying from tens of amperes up to 10 sup 3 A, with current densities up to several amperes per a square centimeter, with pulse duration constituting hundreds of nanoseconds and with high frequencies of repetition

  10. Measurements of current density distribution in shaped e-beam writers

    Czech Academy of Sciences Publication Activity Database

    Bok, Jan; Horáček, Miroslav; Kolařík, Vladimír; Urbánek, Michal; Matějka, Milan; Krzyžánek, Vladislav

    2016-01-01

    Roč. 149, JAN 5 (2016), s. 117-124 ISSN 0167-9317 R&D Projects: GA ČR(CZ) GA14-20012S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : shaped e-beam writer * electron beam * current density Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.806, year: 2016

  11. Novel Programmable Shape Memory Polystyrene Film: A Thermally Induced Beam-power Splitter

    OpenAIRE

    Peng Li; Yu Han; Wenxin Wang; Yanju Liu; Peng Jin; Jinsong Leng

    2017-01-01

    Micro/nanophotonic structures that are capable of optical wave-front shaping are implemented in optical waveguides and passive optical devices to alter the phase of the light propagating through them. The beam division directions and beam power distribution depend on the design of the micro/nanostructures. The ultimate potential of advanced micro/nanophotonic structures is limited by their structurally rigid, functional singleness and not tunable against external impact. Here, we propose a th...

  12. Novel Programmable Shape Memory Polystyrene Film: A Thermally Induced Beam-power Splitter.

    Science.gov (United States)

    Li, Peng; Han, Yu; Wang, Wenxin; Liu, Yanju; Jin, Peng; Leng, Jinsong

    2017-03-09

    Micro/nanophotonic structures that are capable of optical wave-front shaping are implemented in optical waveguides and passive optical devices to alter the phase of the light propagating through them. The beam division directions and beam power distribution depend on the design of the micro/nanostructures. The ultimate potential of advanced micro/nanophotonic structures is limited by their structurally rigid, functional singleness and not tunable against external impact. Here, we propose a thermally induced optical beam-power splitter concept based on a shape memory polystyrene film with programmable micropatterns. The smooth film exhibits excellent transparency with a transmittance of 95% in the visible spectrum and optical stability during a continuous heating process up to 90 °C. By patterning double sided shape memory polystyrene film into erasable and switchable micro-groove gratings, the transmission light switches from one designed light divided directions and beam-power distribution to another because of the optical diffraction effect of the shape changing micro gratings during the whole thermal activated recovery process. The experimental and theoretical results demonstrate a proof-of-principle of the beam-power splitter. Our results can be adapted to further extend the applications of micro/nanophotonic devices and implement new features in the nanophotonics.

  13. Vector vortex beam generation with dolphin-shaped cell meta-surface.

    Science.gov (United States)

    Yang, Zhuo; Kuang, Deng-Feng; Cheng, Fang

    2017-09-18

    We present a dolphin-shaped cell meta-surface, which is a combination of dolphin-shaped metallic cells and dielectric substrate, for vector vortex beam generation with the illumination of linearly polarized light. Surface plasmon polaritons are excited at the boundary of the metallic cells, then guided by the metallic structures, and finally squeezed to the tips to form highly localized strong electromagnetic fields, which generate the intensity of vector vortex beams at z component. Synchronously, the abrupt phase change produced by the meta-surface is utilized to explain the vortex phase generated by elements. The new kind of structure can be utilized for communication, bioscience, and materiality.

  14. The KAERI laser facility with temporal laser beam shaping for application's user

    International Nuclear Information System (INIS)

    Hong, Sung Ki; Kim, Min Suk; Kim, Young Won; Ko, Kwanghoon; Lim, Changhwan; Seo, Young Seok

    2008-01-01

    The Korea Atomic Energy Research Institute(KAERI)has been developed a high energy Nd:Glass laser facility(KLF)for fast ignition research and high energy physics applications at early 2008. Now, we are researching the temporal laser beam shaping for application's user. The temporal laser beam shaping has been applied to a number of industrial applications. The KLF beam shaping system with fiber based consists of two electro optic modulator with DC bias using a Mach Zehnder interferometer, an arbitrary electronic waveform generator, a continuous wavelength fiber laser source, a fiber based pulse amplification system and DC bias source to generate temporally shaped pulses with a high extinction ratio and high resolution. RF signal waveform user defined by an arbitrary electronic waveform generator is only connected to one electro optic modulator. DC bias source with auto feed back or manual controller is connected both two electro optic modulators. Emitting laser light from a continuous wavelength fiber laser source is modulated to meet a user defined laser pulse with a high extinction ratio by two electro optic modulators. Experimental results are shown in Fig.1. Figure 1(a)shows two programmed waveforms with the signal width 10ns in an arbitrary electronic waveform generator. Figure 1(b)shows output laser pulses with sub mJ energy from amplification results of the KLF beam shaping system which can control the pulse width ranges from 400ps to sub us

  15. High efficiency and high-energy intra-cavity beam shaping laser

    International Nuclear Information System (INIS)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-01-01

    We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%. (paper)

  16. High efficiency and high-energy intra-cavity beam shaping laser

    Science.gov (United States)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-09-01

    We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%.

  17. Beam shaping assembly optimization for (7)Li(p,n)(7)Be accelerator based BNCT.

    Science.gov (United States)

    Minsky, D M; Kreiner, A J

    2014-06-01

    Within the framework of accelerator-based BNCT, a project to develop a folded Tandem-ElectroStatic-Quadrupole accelerator is under way at the Atomic Energy Commission of Argentina. The proposed accelerator is conceived to deliver a proton beam of 30mA at about 2.5MeV. In this work we explore a Beam Shaping Assembly (BSA) design based on the (7)Li(p,n)(7)Be neutron production reaction to obtain neutron beams to treat deep seated tumors. © 2013 Elsevier Ltd. All rights reserved.

  18. Proton beam shaped by “particle lens” formed by laser-driven hot electrons

    International Nuclear Information System (INIS)

    Zhai, S. H.; Shen, B. F.; Wang, W. P.; Zhang, H.; Zhang, L. G.; Huang, S.; Xu, Z. Z.; He, S. K.; Lu, F.; Zhang, F. Q.; Deng, Z. G.; Dong, K. G.; Wang, S. Y.; Zhou, K. N.; Xie, N.; Wang, X. D.; Liu, H. J.; Zhao, Z. Q.; Gu, Y. Q.; Zhang, B. H.

    2016-01-01

    Two-dimensional tailoring of a proton beam is realized by a “particle lens” in our experiment. A large quantity of electrons, generated by an intense femtosecond laser irradiating a polymer target, produces an electric field strong enough to change the trajectory and distribution of energetic protons flying through the electron area. The experiment shows that a strip pattern of the proton beam appears when hot electrons initially converge inside the plastic plate. Then the shape of the proton beam changes to a “fountain-like” pattern when these hot electrons diffuse after propagating a distance.

  19. Signal shape registration in the JINR synchrophasotron slowly extracted beam parameter control system

    International Nuclear Information System (INIS)

    Volkov, V.I.; Kulikov, I.I.; Romanov, S.V.

    1982-01-01

    Signal shape registration in the JINR synchrophasotron slowly estracted beam parameter control system on-line with the ES-1010 computer is described. 32 input signals can be connected to the registrator. The maximum measurement rate of signal shape registration is about 38 kHz. The registrator consists of 32-channel analog multiplexer, 10-bit analog-to-digital converter, 1024-word buffer memory and control circuits. For information representation the colour TV monitor is used

  20. Self-focusing and self-defocusing of elliptically shaped Gaussian laser beams in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Nayyar, V P; Soni, V S [Punjabi Univ., Patiala (India). Dept. of Physics

    1979-02-14

    This paper presents a study of the self-focusing and self-defocusing of elliptically shaped Gaussian laser beams in collisional and collisionless plasmas. The non-linear dependence of the dielectric constant inside a collisional plasma is due to inhomogeneous heating of energy carriers and in a collisionless plasma it is due to the ponderomotive force. It is found that the beam gets focused at different points in different planes, exhibiting the effect of astigmatism. In certain power regions considered, the beam either converges or defocuses in both the directions, while in some other regions of the power spectrum one dimension of the beam focuses while the other defocuses. The beam also propagates in an oscillatory waveguide.

  1. Study of the Hollow Waveguides Physical Parameters Determined the Beam Shape Conservation of the Delivered Radiation

    International Nuclear Information System (INIS)

    Ben-David, M.; Inberg, A.; Katzir, A.; Croitoru, N.

    1999-01-01

    The modification of the laser source beam quality is one of the important factors effect the delivery of laser radiation by a waveguide. In this paper the results of input radiation coupling, radius of bending, length, cross section diameter, waveguide internal wall roughness and coupling lens focal length influence on the beam shape delivered from the flexible hollow waveguides are presented. The conditions for which the beam shape is near to that of the source were found. A theoretical model for the radiation propagation gives quantitative representation of relation between attenuation, beam profile, divergence and above indicated parameters was developed. In this model was supposed that the guiding is produced by multiple incidences on a metal (silver) layer and a dielectric (silver iodine) over layer, by refraction and reflection. The propagation of the rays was calculated using the physical laws of the geometrical optics. For the scattering calculations a random distribution of roughness centers on dielectric layer surface was considered. It was also supposed that the value of the cross section internal diameter (ID=d) was much larger than the transmitted wavelength. The experimental results have shown that losses due to absorption of the propagated radiation in the guiding layers, mainly (AgI), generate satellites of the laser source delivered fundamental Gaussian beam. Increasing of the hollow waveguide internal diameter decreases the attenuation and increases the deviation of beam shape from Gaussian. Off center coupling produce decreasing of the fundamental mode height and generation of the coupled Gaussian beam satellites. The waveguide internal wall roughness produce losses of the coupled radiation and beam profile deviations from that of the laser source. A good correspondence between the theoretical and experimental results obtained

  2. The effect of spatial light modulator (SLM) dependent dispersion on spatial beam shaping

    CSIR Research Space (South Africa)

    Spangenberg, D-M

    2013-08-01

    Full Text Available on the pixels between zero and two pi for a specific wavelength. It is therefore unavoidable when using the same SLM, to do beam shaping of a source which emits multiple wavelengths or a wide bandwidth, that the device will not modulate all wavelengths between...

  3. Implementation of intra-cavity beam shaping technique to enhance pump efficiency

    CSIR Research Space (South Africa)

    Litvin, IA

    2012-02-01

    Full Text Available In this work the author proposes an implementation of a new intra-cavity beam shaping technique to vary the intensity distribution of the fundamental mode in a resonator cavity while maintaining a constant intensity distribution at the output...

  4. Minimal-effort planning of active alignment processes for beam-shaping optics

    Science.gov (United States)

    Haag, Sebastian; Schranner, Matthias; Müller, Tobias; Zontar, Daniel; Schlette, Christian; Losch, Daniel; Brecher, Christian; Roßmann, Jürgen

    2015-03-01

    In science and industry, the alignment of beam-shaping optics is usually a manual procedure. Many industrial applications utilizing beam-shaping optical systems require more scalable production solutions and therefore effort has been invested in research regarding the automation of optics assembly. In previous works, the authors and other researchers have proven the feasibility of automated alignment of beam-shaping optics such as collimation lenses or homogenization optics. Nevertheless, the planning efforts as well as additional knowledge from the fields of automation and control required for such alignment processes are immense. This paper presents a novel approach of planning active alignment processes of beam-shaping optics with the focus of minimizing the planning efforts for active alignment. The approach utilizes optical simulation and the genetic programming paradigm from computer science for automatically extracting features from a simulated data basis with a high correlation coefficient regarding the individual degrees of freedom of alignment. The strategy is capable of finding active alignment strategies that can be executed by an automated assembly system. The paper presents a tool making the algorithm available to end-users and it discusses the results of planning the active alignment of the well-known assembly of a fast-axis collimator. The paper concludes with an outlook on the transferability to other use cases such as application specific intensity distributions which will benefit from reduced planning efforts.

  5. Shape invariant higher-order Bessel-like beams carrying orbital angular momentum

    CSIR Research Space (South Africa)

    Ismail, Y

    2012-09-01

    Full Text Available -1 Journal of Optics September 2012/ Vol. 14 Shape invariant higher-order Bessel-like beams carrying orbital angular momentum Y Ismail1,2, N Khilo3, V Belyi3 and A Forbes1,2 1 School of Physics, University of KwaZulu-Natal, Private Bag X54001...

  6. Beam shaping by using small-aperture SLM and DM in a high power laser

    Science.gov (United States)

    Li, Sensen; Lu, Zhiwei; Du, Pengyuan; Wang, Yulei; Ding, Lei; Yan, Xiusheng

    2018-03-01

    High-power laser plays an important role in many fields, such as directed energy weapon, optoelectronic contermeasures, inertial confinement fusion, industrial processing and scientific research. The uniform nearfield and wavefront are the important part of the beam quality for high power lasers, which is conducive to maintaining the high spatial beam quality in propagation. We demonstrate experimentally that the spatial intensity and wavefront distribution at the output is well compensated in the complex high-power solid-state laser system by using the small-aperture spatial light modulator (SLM) and deformable mirror (DM) in the front stage. The experimental setup is a hundred-Joule-level Nd:glass laser system operating at three wavelengths at 1053 nm (1ω), 527 nm (2ω) and 351 nm (3ω) with 3 ns pulse duration with the final output beam aperture of 60 mm. While the clear arperture of the electrically addressable SLM is less than 20 mm and the effective diameter of the 52-actuators DM is about 15 mm. In the beam shaping system, the key point is that the two front-stage beam shaping devices needs to precompensate the gain nonuniform and wavefront distortion of the laser system. The details of the iterative algorithm for improving the beam quality are presented. Experimental results show that output nearfield and wavefont are both nearly flat-topped with the nearfield modulation of 1.26:1 and wavefront peak-to-valley value of 0.29 λ at 1053nm after beam shaping.

  7. SPES-BNCT Project Beam Shaping Assembly. State of the Art

    International Nuclear Information System (INIS)

    Ceballos Sanchez, Cesar

    2007-01-01

    The SPES-BNCT project will exploit the intense proton beam provided by the RFQ (30mA, 5MeV), currently under construction at LNL, to yield a neutron source using the 9 Be(p,xn) nuclear reaction. The goal is to setup an accelerator-driven, thermal neutron beam facility, aimed at the Boron Neutron Capture experimental treatment of extended shallow skin melanoma. The neutron energy spectrum is shifted with a beam shaping assembly (BSA) surrounding the target. This device is fully designed with the Monte Carlo simulation code MCNPX, with the purpose of maximizing the thermal neutron component of the beam and focusing it on the irradiation area. (Author)

  8. High-damage-threshold static laser beam shaping using optically patterned liquid-crystal devices.

    Science.gov (United States)

    Dorrer, C; Wei, S K-H; Leung, P; Vargas, M; Wegman, K; Boulé, J; Zhao, Z; Marshall, K L; Chen, S H

    2011-10-15

    Beam shaping of coherent laser beams is demonstrated using liquid crystal (LC) cells with optically patterned pixels. The twist angle of a nematic LC is locally set to either 0 or 90° by an alignment layer prepared via exposure to polarized UV light. The two distinct pixel types induce either no polarization rotation or a 90° polarization rotation, respectively, on a linearly polarized optical field. An LC device placed between polarizers functions as a binary transmission beam shaper with a highly improved damage threshold compared to metal beam shapers. Using a coumarin-based photoalignment layer, various devices have been fabricated and tested, with a measured single-shot nanosecond damage threshold higher than 30 J/cm2.

  9. Highly integrated optical phased arrays: photonic integrated circuits for optical beam shaping and beam steering

    Science.gov (United States)

    Heck, Martijn J. R.

    2017-01-01

    Technologies for efficient generation and fast scanning of narrow free-space laser beams find major applications in three-dimensional (3D) imaging and mapping, like Lidar for remote sensing and navigation, and secure free-space optical communications. The ultimate goal for such a system is to reduce its size, weight, and power consumption, so that it can be mounted on, e.g. drones and autonomous cars. Moreover, beam scanning should ideally be done at video frame rates, something that is beyond the capabilities of current opto-mechanical systems. Photonic integrated circuit (PIC) technology holds the promise of achieving low-cost, compact, robust and energy-efficient complex optical systems. PICs integrate, for example, lasers, modulators, detectors, and filters on a single piece of semiconductor, typically silicon or indium phosphide, much like electronic integrated circuits. This technology is maturing fast, driven by high-bandwidth communications applications, and mature fabrication facilities. State-of-the-art commercial PICs integrate hundreds of elements, and the integration of thousands of elements has been shown in the laboratory. Over the last few years, there has been a considerable research effort to integrate beam steering systems on a PIC, and various beam steering demonstrators based on optical phased arrays have been realized. Arrays of up to thousands of coherent emitters, including their phase and amplitude control, have been integrated, and various applications have been explored. In this review paper, I will present an overview of the state of the art of this technology and its opportunities, illustrated by recent breakthroughs.

  10. Highly integrated optical phased arrays: photonic integrated circuits for optical beam shaping and beam steering

    Directory of Open Access Journals (Sweden)

    Heck Martijn J.R.

    2016-06-01

    Full Text Available Technologies for efficient generation and fast scanning of narrow free-space laser beams find major applications in three-dimensional (3D imaging and mapping, like Lidar for remote sensing and navigation, and secure free-space optical communications. The ultimate goal for such a system is to reduce its size, weight, and power consumption, so that it can be mounted on, e.g. drones and autonomous cars. Moreover, beam scanning should ideally be done at video frame rates, something that is beyond the capabilities of current opto-mechanical systems. Photonic integrated circuit (PIC technology holds the promise of achieving low-cost, compact, robust and energy-efficient complex optical systems. PICs integrate, for example, lasers, modulators, detectors, and filters on a single piece of semiconductor, typically silicon or indium phosphide, much like electronic integrated circuits. This technology is maturing fast, driven by high-bandwidth communications applications, and mature fabrication facilities. State-of-the-art commercial PICs integrate hundreds of elements, and the integration of thousands of elements has been shown in the laboratory. Over the last few years, there has been a considerable research effort to integrate beam steering systems on a PIC, and various beam steering demonstrators based on optical phased arrays have been realized. Arrays of up to thousands of coherent emitters, including their phase and amplitude control, have been integrated, and various applications have been explored. In this review paper, I will present an overview of the state of the art of this technology and its opportunities, illustrated by recent breakthroughs.

  11. Manual multi-leaf collimator for electron beam shaping - a feasibility study

    International Nuclear Information System (INIS)

    Ravindran, B Paul; Singh, I Rabi Raja; Brindha, S; Sathyan, S

    2002-01-01

    In electron beam therapy, lead or low melting point alloy (LMA) sheet cutouts of sufficient thickness are commonly used to shape the beam. In order to avoid making cutouts for each patient, an attempt has been made to develop a manual multi-leaf collimator for electron beams (eMLC). The eMLC has been developed using LMA for a 15x15 cm 2 applicator. Electron beam characteristics such as depth dose, beam profiles, surface dose, output factors and virtual source position with the eMLC have been studied and compared with those of an applicator electron beam. The interleaf leakage radiation has also been measured with film dosimetry. Depth dose values obtained using the eMLC were found to be identical to those with the applicator for depths larger than D max . However, a decrease in the size of the beam penumbra with the eMLC and increase in the values of surface dose, output factors and virtual source position with eMLC were observed. The leakage between the leaves was less than 5% and the leakage between the opposing leaves was 15%, which could be minimized further by careful positioning of the leaves. It is observed that it is feasible to use such a manual eMLC for patients and eliminate the fabrication of cutouts for each patient

  12. Transverse Laser Beam Shaping in High Brightness Electron Gun at ATF

    CERN Document Server

    Roychowdhury, S

    2005-01-01

    The brightness of electron beams from a photo injector is influenced by the transverse and longitudinal distribution of the laser beam illuminating the cathode. Previous studies at Brookhaven Accelerator Test Facility have shown that formation of an ideal e-beam with lowest transverse emittance requires uniform circular distribution of the emitted electrons. The use of the uniformly distributed power of the laser beam may not lead to that of the emitted electrons because of the non-uniform quantum efficiency. A proper shaping of the laser beam can compensate for this non-uniformity. In this paper we describe the use of digital light processing (DLP) technique based on digital mirror device (DMD) for spatial modulation of the laser beam, for measurements of the quantum efficiency map, and for creating the desirable e-beam density profiles. A DMD is aμelectronic mechanical system (MEMS) comprising of millions of highly reflectiveμmirrors controlled by underlying electronics. We present exper...

  13. Estimating the vibration level of an L-shaped beam using power flow techniques

    Science.gov (United States)

    Cuschieri, J. M.; Mccollum, M.; Rassineux, J. L.; Gilbert, T.

    1986-01-01

    The response of one component of an L-shaped beam, with point force excitation on the other component, is estimated using the power flow method. The transmitted power from the source component to the receiver component is expressed in terms of the transfer and input mobilities at the excitation point and the joint. The response is estimated both in narrow frequency bands, using the exact geometry of the beams, and as a frequency averaged response using infinite beam models. The results using this power flow technique are compared to the results obtained using finite element analysis (FEA) of the L-shaped beam for the low frequency response and to results obtained using statistical energy analysis (SEA) for the high frequencies. The agreement between the FEA results and the power flow method results at low frequencies is very good. SEA results are in terms of frequency averaged levels and these are in perfect agreement with the results obtained using the infinite beam models in the power flow method. The narrow frequency band results from the power flow method also converge to the SEA results at high frequencies. The advantage of the power flow method is that detail of the response can be retained while reducing computation time, which will allow the narrow frequency band analysis of the response to be extended to higher frequencies.

  14. Design of a beam shaping assembly for an accelerator-based BNCT system

    International Nuclear Information System (INIS)

    Stichelbaut, F.; Forton, E.; Jongen, Y.

    2006-01-01

    A complete BNCT system based on a high-intensity proton accelerator is developed by the IBA company. The neutron beam is produced via the 7 Li(p,n) 7 Be reaction using a solid lithium target. The neutron energy spectrum is tailored with a beam shaping assembly surrounding the target. This device is the object of an extensive R and D project and is fully designed with the Monte Carlo simulation code MCNPX. The emphasis is put on the treatment quality, notably the radiation dose at the skin level, and the achievable neutron flux. (author)

  15. Obtaining the Bunch Shape in a Linac from Beam Spectrum Measurements

    International Nuclear Information System (INIS)

    Bane, Karl LF

    1999-01-01

    In linacs with high single-bunch charge, and tight tolerances for energy spread and emittance growth, controlling the short-range wakefield effects becomes extremely important. The effects of the wakefields, in turn, depend on the bunch length and also on the bunch shape. It was shown in the linac of the Stanford Linear Collider (SLC), for example, that by shaping the bunch, the final rms energy spread could be greatly reduced, compared to for the standard Gaussian bunch shape[1]. Therefore, in machines with high single-bunch charge, a method of measuring bunch shape can be an important beam diagnostic. In a linac with low single-bunch charge, the longitudinal bunch shape can be obtained relatively easily from a single measurement of the beam's final energy spectrum, provided that the final to initial energy ratio is large. One merely shifts the average phase of the beam, so that it rides off-crest sufficiently to induce an energy variation that is monotonic with longitudinal position. Then, by knowing the initial and final energies, the rf wave number, and the average beam phase, one can directly map the spectrum into the bunch shape. In a linac with high single-bunch charge, however, due to the effect of the longitudinal wakefield, this method either does not work at all, or it requires such a large shift in beam phase as to become impractical. In earlier work[2],[3] it was shown that, even when wakefields are important, if one measures the final beam spectrum for two different (properly chosen) values of beam phase, then one can again obtain the bunch shape, and--as a by-product--also the form of the wakefield induced voltage; this method was then illustrated using data from the linac of the SLC. These SLC measurements, however, had been performed with the machine in a special configuration, where the current was low; in addition, the noise the data was low and the measured spectra were smooth distributions. Under normal SLC conditions, however, the currents

  16. Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe [Northern Illinois U.

    2015-12-01

    Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

  17. The measurement of neutral beam thermal profiles on 'V'-shaped calorimeters

    International Nuclear Information System (INIS)

    Kamperschroer, J.H.; Lagin, L.J.; Silber, K.

    1995-01-01

    It is customary in high power neutral beam systems to use a V-shaped calorimeter to stop and measure the beam. With proper instrumentation, it is possible to determine both the neutral beam power and divergence. By utilizing a near-grazing angle of incidence, the area over which the beam is in contact with the surface is increased, thereby decreasing the power density over the case of normal incidence. Thermocouples on the back of the calorimeter, in conjunction with real time fitting algorithms, are used to deduce the divergence from the thermal profile. This measurement implicitly assumes that the measured profile corresponds to that of the incident beam. It is shown that such is not the case. Energetic particle reflection at near-grazing angle causes the thermal profile on the calorimeter to be more peaked than the incident distribution. The implications of this on the non-linear multiple regression technique of determining the divergence are discussed. With the aid of a reflection model, developed and applied to the beam from a typical TFTR ion source, it is shown that a peaked power density can be modelled. Neural networks are being studied as a means of supplanting the older regression technique of measuring divergence. Y-direction divergences have been successfully derived using a one-dimensional neural network

  18. Numerical simulation of Gaussian beam scattering by complex particles of arbitrary shape and structure

    International Nuclear Information System (INIS)

    Han, Y.P.; Cui, Z.W.; Gouesbet, G.

    2012-01-01

    An efficient numerical method based on the surface integral equations is introduced to simulate the scattering of Gaussian beam by complex particles that consist of an arbitrarily shaped host particle and multiple internal inclusions of arbitrary shape. In particular, the incident focused Gaussian beam is described by the Davis fifth-order approximate expressions in combination with rotation defined by Euler angles. The established surface integral equations are discretized with the method of moments, where the unknown equivalent electric and magnetic currents induced on the surfaces of the host particle and the internal inclusions are expanded using the Rao-Wilton-Glisson (RWG) basis functions. The resultant matrix equations are solved by using the parallel conjugate gradient method. The proposed numerical method is validated and its capability illustrated in several characteristic examples.

  19. Metasurfaces-based holography and beam shaping: engineering the phase profile of light

    Directory of Open Access Journals (Sweden)

    Scheuer Jacob

    2016-08-01

    Full Text Available The ability to engineer and shape the phase profile of optical beams is in the heart of any optical element. Be it a simple lens or a sophisticated holographic element, the functionality of such components is dictated by their spatial phase response. In contrast to conventional optical components which rely on thickness variation to induce a phase profile, metasurfaces facilitate the realization of arbitrary phase distributions using large arrays with sub-wavelength and ultrathin (tens of nanometers features. Such components can be easily realized using a single lithographic step and is highly suited for patterning a variety of substrates, including nonplanar and soft surfaces. In this article, we review the recent developments, potential, and opportunities of metasurfaces applications. We focus primarily on flat optical devices, holography, and beam-shaping applications as these are the key ingredients needed for the development of a new generation of optical devices which could find widespread applications in photonics.

  20. Treatment planning capability assessment of a beam shaping assembly for accelerator-based BNCT.

    Science.gov (United States)

    Herrera, M S; González, S J; Burlon, A A; Minsky, D M; Kreiner, A J

    2011-12-01

    Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT) a theoretical study was performed to assess the treatment planning capability of different configurations of an optimized beam shaping assembly for such a facility. In particular this study aims at evaluating treatment plans for a clinical case of Glioblastoma. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Treatment planning capability assessment of a beam shaping assembly for accelerator-based BNCT

    International Nuclear Information System (INIS)

    Herrera, M.S.; González, S.J.; Burlon, A.A.; Minsky, D.M.; Kreiner, A.J.

    2011-01-01

    Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT) a theoretical study was performed to assess the treatment planning capability of different configurations of an optimized beam shaping assembly for such a facility. In particular this study aims at evaluating treatment plans for a clinical case of Glioblastoma.

  2. The Researches on I-beam of different web’s shapes

    Science.gov (United States)

    Shuang, Chao; Zhou, Dong Hua

    2018-05-01

    When the ratio of height to thickness of girder web is relatively high, generally the local stability of web is enhanced by setting up stiffeners. But setting up stiffeners not only increase the use of material, but also increases the welding work. Therefore, the web can be processed into trapezoid, curve, triangles and rectangle to improve its stability. In order to study the mechanical behavior of the web with different shapes and its local stable bearing capacity, the finite element analysis software ANSYS was used to analyze the six I-beam, and the stress characteristics under different web forms were obtained. The results show that the local stability bearing capacity of the I-beam is improved, especially the shape of the trapezoidal web and the shape of the curved web have a significant effect on the local stability of the I-beam. Finally, based on the study of the local stability of the trapezoidal web and the curved web, the influence of their geometrical dimensions on the local stable bearing capacity is also studied.

  3. A mathematical model for smart functionally graded beam integrated with shape memory alloy actuators

    International Nuclear Information System (INIS)

    Sepiani, H.; Ebrahimi, F.; Karimipour, H.

    2009-01-01

    This paper presents a theoretical study of the thermally driven behavior of a shape memory alloy (SMA)/FGM actuator under arbitrary loading and boundary conditions by developing an integrated mathematical model. The model studied is established on the geometric parameters of the three-dimensional laminated composite box beam as an actuator that consists of a functionally graded core integrated with SMA actuator layers with a uniform rectangular cross section. The constitutive equation and linear phase transformation kinetics relations of SMA layers based on Tanaka and Nagaki model are coupled with the governing equation of the actuator to predict the stress history and to model the thermo-mechanical behavior of the smart shape memory alloy/FGM beam. Based on the classical laminated beam theory, the explicit solution to the structural response of the structure, including axial and lateral deflections of the structure, is investigated. As an example, a cantilever box beam subjected to a transverse concentrated load is solved numerically. It is found that the changes in the actuator's responses during the phase transformation due to the strain recovery are significant

  4. Beam shaping for multicolour light-emitting diodes with diffractive optical elements

    KAUST Repository

    Yu, Chao

    2016-10-06

    An improved particle swarm optimization method is proposed for the design of ultra-thin diffractive optical elements (DOEs) enabling multicolour beam shaping functionality. We employ pre-optimized initial structures and adaptive weight strategy in the algorithm to achieve better and identical shaping performance for multiple colours. Accordingly, a DOE for shaping light from green and blue LEDs has been designed and fabricated. Both experiment and numerical simulations have been conducted and the results agree well with each other. 15.66% average root mean square error (RMSE) and 0.22% RMSE difference are achieved. In addition, the parameters closely related to the performance of the optimization are analysed, which can provide insights for future application designs.

  5. Tabulated square-shaped source model for linear accelerator electron beam simulation.

    Science.gov (United States)

    Khaledi, Navid; Aghamiri, Mahmood Reza; Aslian, Hossein; Ameri, Ahmad

    2017-01-01

    Using this source model, the Monte Carlo (MC) computation becomes much faster for electron beams. The aim of this study was to present a source model that makes linear accelerator (LINAC) electron beam geometry simulation less complex. In this study, a tabulated square-shaped source with transversal and axial distribution biasing and semi-Gaussian spectrum was investigated. A low energy photon spectrum was added to the semi-Gaussian beam to correct the bremsstrahlung X-ray contamination. After running the MC code multiple times and optimizing all spectrums for four electron energies in three different medical LINACs (Elekta, Siemens, and Varian), the characteristics of a beam passing through a 10 cm × 10 cm applicator were obtained. The percentage depth dose and dose profiles at two different depths were measured and simulated. The maximum difference between simulated and measured percentage of depth doses and dose profiles was 1.8% and 4%, respectively. The low energy electron and photon spectrum and the Gaussian spectrum peak energy and associated full width at half of maximum and transversal distribution weightings were obtained for each electron beam. The proposed method yielded a maximum computation time 702 times faster than a complete head simulation. Our study demonstrates that there was an excellent agreement between the results of our proposed model and measured data; furthermore, an optimum calculation speed was achieved because there was no need to define geometry and materials in the LINAC head.

  6. A tolerance analysis on design parameters of parabolic and hyperbolic secant active GRIN materials for laser beam shaping purposes

    International Nuclear Information System (INIS)

    Gómez-Varela, A I; Bao-Varela, C; Flores-Arias, M T

    2014-01-01

    The present paper considers two gain GRIN media, characterized by a complex parabolic and hyperbolic secant refractive index profile, for the design of uniform beam shaper systems. A general condition for beam shaping is obtained from the equation describing the evolution of the half-width of a plane Gaussian beam in the GRIN media. The simulation of the irradiance evolution of an input plane Gaussian beam—operating at 575 nm and beam waist radius of 0.45 mm—in each material is shown, in order to examine the beam shaping quality in terms of thickness of the active GRIN media and input beam wavelength. (paper)

  7. Complex calculation and improvement of beam shaping and accelerating system of the ''Sokol'' small-size electrostatic accelerator

    International Nuclear Information System (INIS)

    Simonenko, A.V.; Pistryak, V.M.; Zats, A.V.; Levchenko, Yu.Z.; Kuz'menko, V.V.

    1987-01-01

    Features of charged particle accelerated beam shaping in the electrostatic part of the ''Sokol'' small-size accelerator are considered in complex taking into account the electrode real geometry. Effect of the extracting, accelerating electorde potential and accelerator total voltage on beam behaviour is investigated. A modified variation of the beam shaping system, allowing to decrease 2 times the required interval of accelerating electrode potential adjustment and to decrease the beam size in the starting acceleration region, is presented. It permits to simplify the construction and to improve accelerator operation. Comparison of experimental and calculational data on the beam in the improved accelerator variation is carried out. Effect of peripheral parts of accelerating tube electrodes on the beam is investigated

  8. Pulsed high field magnets. An efficient way of shaping laser accelerated proton beams for application

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Florian; Schramm, Ulrich [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany); Technische Universitaet Dresden, 01062 Dresden (Germany); Bagnoud, Vincent; Blazevic, Abel; Busold, Simon [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Helmholtz Institut Jena, 07734 Jena (Germany); Brabetz, Christian; Schumacher, Dennis [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Deppert, Oliver; Jahn, Diana; Roth, Markus [Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Karsch, Leonhard; Masood, Umar [OncoRay-National Center for Radiation Research in Oncology, TU Dresden, 01307 Dresden (Germany); Kraft, Stephan [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany)

    2015-07-01

    Compact laser-driven proton accelerators are a potential alternative to complex, expensive conventional accelerators, enabling unique beam properties, like ultra-high pulse dose. Nevertheless, they still require substantial development in reliable beam generation and transport. We present experimental studies on capture, shape and transport of laser and conventionally accelerated protons via pulsed high-field magnets. These magnets, common research tools in the fields of solid state physics, have been adapted to meet the demands of laser acceleration experiments.Our work distinctively shows that pulsed magnet technology makes laser acceleration more suitable for application and can facilitate compact and efficient accelerators, e.g. for material research as well as medical and biological purposes.

  9. Optimal Neutron Source and Beam Shaping Assembly for Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    Vujic, J.; Greenspan, E.; Kastenber, W.E.; Karni, Y.; Regev, D.; Verbeke, J.M.; Leung, K.N.; Chivers, D.; Guess, S.; Kim, L.; Waldron, W.; Zhu, Y.

    2003-01-01

    There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly

  10. Effects of laser beam propagation and saturation on the spatial shape of sodium laser guide stars.

    Science.gov (United States)

    Marc, Fabien; Guillet de Chatellus, Hugues; Pique, Jean-Paul

    2009-03-30

    The possibility to produce diffraction-limited images by large telescopes through Adaptive Optics is closely linked to the precision of measurement of the position of the guide star on the wavefront sensor. In the case of laser guide stars, many parameters can lead to a strong distortion on the shape of the LGS spot. Here we study the influence of both the saturation of the sodium layer excited by different types of lasers, the spatial quality of the laser mode at the ground and the influence of the atmospheric turbulence on the upward propagation of the laser beam. Both shape and intensity of the LGS spot are found to depend strongly on these three effects with important consequences on the precision on the wavefront analysis.

  11. Development of bunch shape monitor for high-intensity beam on the China ADS proton LINAC Injector II

    Science.gov (United States)

    Zhu, Guangyu; Wu, Junxia; Du, Ze; Zhang, Yong; Xue, Zongheng; Xie, Hongming; Wei, Yuan; Jing, Long; Jia, Huan

    2018-05-01

    The development, performance, and testing of the longitudinal bunch shape monitor, namely, the Fast Faraday Cup (FFC), are presented in this paper. The FFC is an invasive instrument controlled by a stepper motor, and its principle of operation is based on a strip line structure. The longitudinal bunch shape was determined by sampling a small part of the beam hitting the strip line through a 1-mm hole. The rise time of the detector reached 24 ps. To accommodate experiments that utilize high-intensity beams, the materials of the bunch shape monitor were chosen to sustain high temperatures. Water cooling was also integrated in the detector system to enhance heat transfer and prevent thermal damage. We also present an analysis of the heating caused by the beam. The bunch shape monitor has been installed and commissioned at the China ADS proton LINAC Injector II.

  12. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Moteabbed, Maryam, E-mail: mmoteabbed@partners.org; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-05-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D{sub mean}) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D{sub mean} and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D{sub mean} and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  13. Finite Element Analysis of the Pseudo-elastic Behavior of Shape Memory Alloy Truss and Beam

    Directory of Open Access Journals (Sweden)

    Kamal M. Bajoria

    2010-07-01

    Full Text Available The pseudo-elastic behavior of Shape memory alloy (SMA truss and cantilever beam are investigated. Brinson’s one-dimensional material model, which uses the twinned and detwinned martensite fractions separately as internal variables, is applied in the algorithm to establish the SMA stress-strain characteristics. This material model also incorporates different young’s modulus for austenitic and martensite phase to represent the true SMA characteristics. In this model, a cosine function was used to express the evolution of the stress induced martensite fractions during the forward and reverse martensite phase transformation. A finite element formulation for the SMA truss member considering the geometric nonlinearity is proposed and the results are compared with the corresponding linear analysis. As a step forward, a finite element formulation for an SMA cantilever beam with an applied end moment is proposed. The load displacement characteristic for both the loading and unloading phases are considered to check the full pseudo-elastic hysteretic loop. In the numerical investigation, the stress-strain variation along the beam depth is also examined during the loading and unloading process to investigate the forward and reverse martensite phase transformation phenomena. Newton-Raphson’s iterative method is applied to get convergence to the equilibrium for each loading steps. During a complete loading-unloading process, the temperature is kept constant as the model is essentially an isothermal model. Numerical simulation is performed considering two different temperatures to demonstrate the effect of temperature on the hysteretic loop.

  14. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies

    Science.gov (United States)

    Zhao, Nian; Yang, Jin; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping

    2016-01-01

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.

  15. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies

    International Nuclear Information System (INIS)

    Zhao, Nian; Yang, Jin; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping

    2016-01-01

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life

  16. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies.

    Science.gov (United States)

    Zhao, Nian; Yang, Jin; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping

    2016-01-01

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.

  17. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Nian; Yang, Jin, E-mail: yangjin@cqu.edu.cn; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping [Department of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2016-01-15

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.

  18. Effect of laser beam on temperature distribution on artificial cylindrical shaped hard tissue bones

    Science.gov (United States)

    Al-Akhras, M.-Ali H.; Qaseer, Mohammad-Khair; Albiss, B. A.; Gezawa, Umar S.

    2018-02-01

    Samples from fresh lamb chest bones were made in cylindrical shapes to study the time variation of temperature T as functions of the cylindrical radius and depth when its front surface exposed to a laser beam of 110Mw power and 642nm wavelength. The laser beam was directed at the center of the front surface of the horizontal cylinder. The measurements were done in vacuum and at atmospheric pressure. Our data reveal the linear variation of T with time, followed by a gradual increase before it reaches a plateau value at higher time. This sort of behavior independent of the radius or the depth where the temperature was measured. Moreover, the maximum variation occurs on the front surface where the laser beam was hitting and diminishes gradually with depth deep inside the cylinder. Data at atmospheric pressure showed less changes in temperature. The temperature distribution in bone due to laser irradiation is very important for a rational use of laser therapy as well as in the surgery to minimizes the thermal tissue damage.

  19. Numerical simulation of the processes of small-diameter high-current electron beam shaping and injection

    CERN Document Server

    Gordeev, V S; Myskov, G A

    2001-01-01

    With the aid of BEAM 25 program there was carried out the numerical simulation of the non-stationary process of shaping a small-diameter (<= 20mm) high-current hollow electron beam in a diode with magnetic insulation,as well as of the process of beam injection into the accelerating LIA track. The diode configuration for the purpose of eliminating the leakage of electron flux to the anode surface was update. Presented are the results of calculation of the injected beam characteristics (amplitude-time parameters of a current pulse, space-angle distributions of electrons etc.) depending on diode geometric parameters.

  20. A method for robust segmentation of arbitrarily shaped radiopaque structures in cone-beam CT projections

    International Nuclear Information System (INIS)

    Poulsen, Per Rugaard; Fledelius, Walther; Keall, Paul J.; Weiss, Elisabeth; Lu Jun; Brackbill, Emily; Hugo, Geoffrey D.

    2011-01-01

    Purpose: Implanted markers are commonly used in radiotherapy for x-ray based target localization. The projected marker position in a series of cone-beam CT (CBCT) projections can be used to estimate the three dimensional (3D) target trajectory during the CBCT acquisition. This has important applications in tumor motion management such as motion inclusive, gating, and tumor tracking strategies. However, for irregularly shaped markers, reliable segmentation is challenged by large variations in the marker shape with projection angle. The purpose of this study was to develop a semiautomated method for robust and reliable segmentation of arbitrarily shaped radiopaque markers in CBCT projections. Methods: The segmentation method involved the following three steps: (1) Threshold based segmentation of the marker in three to six selected projections with large angular separation, good marker contrast, and uniform background; (2) construction of a 3D marker model by coalignment and backprojection of the threshold-based segmentations; and (3) construction of marker templates at all imaging angles by projection of the 3D model and use of these templates for template-based segmentation. The versatility of the segmentation method was demonstrated by segmentation of the following structures in the projections from two clinical CBCT scans: (1) Three linear fiducial markers (Visicoil) implanted in or near a lung tumor and (2) an artificial cardiac valve in a lung cancer patient. Results: Automatic marker segmentation was obtained in more than 99.9% of the cases. The segmentation failed in a few cases where the marker was either close to a structure of similar appearance or hidden behind a dense structure (data cable). Conclusions: A robust template-based method for segmentation of arbitrarily shaped radiopaque markers in CBCT projections was developed.

  1. Treatment of absolute painful glaucoma with dynamic arcs using novalis shaped beam radiosurgery

    International Nuclear Information System (INIS)

    Gonzalez-Olhovich, Irene; Celis, Miguel Angel; Larraga-Gutierrez, Jose; Lopez-Ayala, Temuchino; Suarez-Campos, Jose; Garcia-Garduno, Amanda; Herrera-Gomez, Leopoldo; Hernandez-Bojorquez, Mariana B.Sc.

    2006-01-01

    Purpose: We assessed the effect of shaped beam conformal stereotactic radiosurgery (SRS) in 1 patient with chronic painful glaucoma in one eye refractory to medical treatment. Methods and Materials: Left eye ciliary body was targeted at 18 Gy (90% isodose curve) with a dedicated linear accelerator (Novalis, BrainLAB, Germany) SRS. Interval follow-up was performed weekly for the first month, and every 2 months until 1 year was completed with clinical examinations and intraocular pressure (IOP) measurements. Results: Ocular pain resolved at 6 weeks after SRS treatment. IOP decreased and normalized at 1 year. Conclusions: We present a case in which SRS appears to be an effective treatment of chronic refractory painful glaucoma. Further Phase I studies are needed to know the best parameters for radiation dose, tolerance of organs at risk, and pathophysiologic effects

  2. Visible microactuation of a ferromagnetic shape memory alloy by focused laser beam

    International Nuclear Information System (INIS)

    Hu, Zhibin; Tamang, Rajesh; Varghese, Binni; Sow, Chorng-Haur; Rajini Kanth, B; Mukhopadhyay, P K

    2012-01-01

    We used a focused laser beam to achieve large amplitude and localized controlled actuation in a microstructure made of a ferromagnetic shape memory alloy. Significant deformation (18 µm) was achieved at low laser power (20 mW) and the amplitude of actuation could be linearly controlled with the laser power. The rapid mechanical actuation shows no apparent sign of fatigue even after a million continuous oscillatory cycles. As a possible mechanism, we propose that the deformation of structure was induced by a combination of the thermal effect and the magnetic field of the incident laser light. This is possibly the first such reported visual evidence of microactuation of materials due to the optomagnetic field. (fast track communication)

  3. $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with radioactive At beams

    CERN Multimedia

    We propose to study the $\\beta$-delayed fission, laser spectroscopy and radioactive decay of the newly available pure beams of neutron-deficient and neutron-rich astatine (Z=85) isotopes. The fission probability and the fission fragment distribution of the even-even isotopes $^{194,196}$Po following the $\\beta$-decay of the isotopes $^{194,196}$At will be studied with the Windmill setup. In-source laser spectroscopy will be performed on the entire astatine isotopic chain, using a combination of the Windmill setup, ISOLTRAP MR-ToF and ISOLDE Faraday. Radioactive decay data will be acquired at the Windmill setup throughout those studies and contribute to the global understanding of the phenomenon of shape coexistence in the neutron-deficient lead region.

  4. Compact multimode fiber beam-shaping system based on GPU accelerated digital holography.

    Science.gov (United States)

    Plöschner, Martin; Čižmár, Tomáš

    2015-01-15

    Real-time, on-demand, beam shaping at the end of the multimode fiber has recently been made possible by exploiting the computational power of rapidly evolving graphics processing unit (GPU) technology [Opt. Express 22, 2933 (2014)]. However, the current state-of-the-art system requires the presence of an acousto-optic deflector (AOD) to produce images at the end of the fiber without interference effects between neighboring output points. Here, we present a system free from the AOD complexity where we achieve the removal of the undesired interference effects computationally using GPU implemented Gerchberg-Saxton and Yang-Gu algorithms. The GPU implementation is two orders of magnitude faster than the CPU implementation which allows video-rate image control at the distal end of the fiber virtually free of interference effects.

  5. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Moteabbed, Maryam; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-01-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D_m_e_a_n) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D_m_e_a_n and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D_m_e_a_n and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  6. X-ray beam-shaping via deformable mirrors: Analytical computation of the required mirror profile

    International Nuclear Information System (INIS)

    Spiga, Daniele; Raimondi, Lorenzo; Svetina, Cristian; Zangrando, Marco

    2013-01-01

    X-ray mirrors with high focusing performances are in use in both mirror modules for X-ray telescopes and in synchrotron and FEL (Free Electron Laser) beamlines. A degradation of the focus sharpness arises in general from geometrical deformations and surface roughness, the former usually described by geometrical optics and the latter by physical optics. In general, technological developments are aimed at a very tight focusing, which requires the mirror profile to comply with the nominal shape as much as possible and to keep the roughness at a negligible level. However, a deliberate deformation of the mirror can be made to endow the focus with a desired size and distribution, via piezo actuators as done at the EIS-TIMEX beamline of FERMI@Elettra. The resulting profile can be characterized with a Long Trace Profilometer and correlated with the expected optical quality via a wavefront propagation code. However, if the roughness contribution can be neglected, the computation can be performed via a ray-tracing routine, and, under opportune assumptions, the focal spot profile (the Point Spread Function, PSF) can even be predicted analytically. The advantage of this approach is that the analytical relation can be reversed; i.e., from the desired PSF the required mirror profile can be computed easily, thereby avoiding the use of complex and time-consuming numerical codes. The method can also be suited in the case of spatially inhomogeneous beam intensities, as commonly experienced at synchrotrons and FELs. In this work we expose the analytical method and the application to the beam shaping problem

  7. Error in the determination of the deformed shape of prismatic beams using the double integration of curvature

    Science.gov (United States)

    Sigurdardottir, Dorotea H.; Stearns, Jett; Glisic, Branko

    2017-07-01

    The deformed shape is a consequence of loading the structure and it is defined by the shape of the centroid line of the beam after deformation. The deformed shape is a universal parameter of beam-like structures. It is correlated with the curvature of the cross-section; therefore, any unusual behavior that affects the curvature is reflected through the deformed shape. Excessive deformations cause user discomfort, damage to adjacent structural members, and may ultimately lead to issues in structural safety. However, direct long-term monitoring of the deformed shape in real-life settings is challenging, and an alternative is indirect determination of the deformed shape based on curvature monitoring. The challenge of the latter is an accurate evaluation of error in the deformed shape determination, which is directly correlated with the number of sensors needed to achieve the desired accuracy. The aim of this paper is to study the deformed shape evaluated by numerical double integration of the monitored curvature distribution along the beam, and create a method to predict the associated errors and suggest the number of sensors needed to achieve the desired accuracy. The error due to the accuracy in the curvature measurement is evaluated within the scope of this work. Additionally, the error due to the numerical integration is evaluated. This error depends on the load case (i.e., the shape of the curvature diagram), the magnitude of curvature, and the density of the sensor network. The method is tested on a laboratory specimen and a real structure. In a laboratory setting, the double integration is in excellent agreement with the beam theory solution which was within the predicted error limits of the numerical integration. Consistent results are also achieved on a real structure—Streicker Bridge on Princeton University campus.

  8. Shaping symmetric Airy beam through binary amplitude modulation for ultralong needle focus

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhao-Xiang; Gong, Lei [Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei 230026 (China); Ren, Yu-Xuan, E-mail: yxren@ustc.edu.cn [National Center for Protein Sciences Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Shanghai 200031 (China); Vaveliuk, Pablo [Centro de Investigaciones Opticas (CONICET La Plata-CIC), Cno. Centenario y 506, P.O. Box 3, 1897 Gonnet, La Plata, Pcia. de Buenos Aires (Argentina); Chen, Yue; Lu, Rong-De, E-mail: lrd@ustc.edu.cn [Physics Experiment Teaching Center, School of Physical Sciences, University of Science and Technology of China, Hefei 230026 (China)

    2015-11-28

    Needle-like electromagnetic field has various advantages for the applications in high-resolution imaging, Raman spectroscopy, as well as long-distance optical transportation. The realization of such field often requires high numerical aperture (NA) objective lens and the transmission masks. We demonstrate an ultralong needle-like focus in the optical range produced with an ordinary lens. This is achieved by focusing a symmetric Airy beam (SAB) generated via binary spectral modulation with a digital micromirror device. Such amplitude modulation technique is able to shape traditional Airy beams, SABs, as well as the dynamic transition modes between the one-dimensional and two-dimensional (2D) symmetric Airy modes. The created 2D SAB was characterized through measurement of the propagating fields with one of the four main lobes blocked by an opaque mask. The 2D SAB was verified to exhibit self-healing property against propagation with the obstructed major lobe reconstructed after a certain distance. We further produced an elongated focal line by concentrating the SAB via lenses with different NAs and achieved an ultralong longitudinal needle focus. The produced long needle focus will be applied in optical, chemical, and biological sciences.

  9. Laser diode stack beam shaping for efficient and compact long-range laser illuminator design

    Science.gov (United States)

    Lutz, Y.; Poyet, J. M.

    2014-04-01

    Laser diode stacks are interesting laser sources for active imaging illuminators. They allow the accumulation of large amounts of energy in multi-pulse mode, which is best suited for long-range image recording. Even when the laser diode stacks are equipped with fast-axis collimation (FAC) and slow-axis collimation (SAC) micro-lenses, their beam parameter products BPP are not compatible with direct use in highly efficient and compact illuminators. This is particularly true when narrow divergences are required such as for long-range applications. A solution to overcome these difficulties is to enhance the poor slow-axis BPP by virtually restacking the laser diode stack. We present a beam shaping and homogenization method that is low-cost and efficient and has low alignment sensitivity. After conducting simulations, we have realized and characterized the illuminator. A compact long-range laser illuminator has been set up with a divergence of 3.5×2.6 mrad and a global efficiency of 81%. Here, a projection lens with a clear aperture of 62 mm and a focal length of 571 mm was used.

  10. A novel design of beam shaping assembly to use D-T neutron generator for BNCT.

    Science.gov (United States)

    Kasesaz, Yaser; Karimi, Marjan

    2016-12-01

    In order to use 14.1MeV neutrons produced by d-T neutron generators, two special and novel Beam Shaping Assemblies (BSA), including multi-layer and hexagonal lattice have been suggested and the effect of them has been investigated by MCNP4C Monte Carlo code. The results show that the proposed BSA can provide the qualified epithermal neutron beam for BNCT. The final epithermal neutron flux is about 6e9 n/cm2.s. The final proposed BSA has some different advantages: 1) it consists of usual and well-known materials (Pb, Al, Fluental and Cd); 2) it has a simple geometry; 3) it does not need any additional gamma filter; 4) it can provide high flux of epithermal neutrons. As this type of neutron source is under development in the world, it seems that they can be used clinically in a hospital considering the proposed BSA. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Investigation of an He-Ne laser generating a beam with a ring-shaped intensity distribution

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, I I; Troitskii, IU V; Iakushkin, S V

    1987-02-01

    The paper examines an He-Ne laser regime with the simultaneous generation of TEM(01) and TEM(10) modes, forming a beam with a ring-shaped intensity distribution with total suppression of the TEM(00) mode. The ratio of the intensity at the ring crest to the intensity at the axis reached a value of 200 and was limited by scattering in the optical components of the resonator. A regime of mutual frequency locking of the TEM(01) and TEM(10) modes was achieved with total spatial coherence of the ring-shaped beam. 14 references.

  12. Shaping of Au nanoparticles embedded in various layered structures by swift heavy ion beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Dawi, E.A., E-mail: elmuez.dawi@gmail.com [Ajman University of Science and Technology, Basic Science and Education, Physics Department, P.O. Box 346 (United Arab Emirates); Debye Institute for Nanomaterials, Nanophotonics Section, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands); ArnoldBik, W.M. [Eindhoven University of Technology, Irradiation Technology, 5600 GM Eindhoven (Netherlands); Ackermann, R.; Habraken, F.H.P.M. [Debye Institute for Nanomaterials, Nanophotonics Section, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands)

    2016-10-01

    We present a novel method to extend the ion-beam induced shaping of metallic nanoparticles in various layered structures. Monodisperse Au nanoparticles having mean diameter of 30 nm and their ion-shaping process is investigated for a limited number of experimental conditions. Au nanoparticles were embedded within a single plane in various layered structures of silicon nitride films (Si{sub 3}N{sub 4}), combinations of oxide-nitride films (SiO{sub 2}-Si{sub 3}N{sub 4}) and amorphous silicon films (a-Si) and have been sequentially irradiated at 300 K at normal incidence with 50 and 25 MeV Ag ions, respectively. Under irradiation with heavy Ag ions and with sequential increase of the irradiation fluence, the evolution of the Au peak derived from the Rutherford Backscattering Spectrometry show broadening in Au peak, which indicates that the Au becomes distributed over a larger depth region, indicative of the elongation of the nanoparticles. The latter is observed almost for every layer structure investigated except for Au nanoparticles embedded in pure a-Si matrix. The largest elongation rate at all fluences is found for the Au nanoparticles encapsulated in pure Si{sub 3}N{sub 4} films. For all irradiation energy applied, we again demonstrate the existence of both threshold and saturation fluences for the elongation effects mentioned.

  13. A study of composite beam with shape memory alloy arbitrarily embedded under thermal and mechanical loadings

    International Nuclear Information System (INIS)

    Zhang Yin; Zhao Yapu

    2007-01-01

    The constitutive relations and kinematic assumptions on the composite beam with shape memory alloy (SMA) arbitrarily embedded are discussed and the results related to the different kinematic assumptions are compared. As the approach of mechanics of materials is to study the composite beam with the SMA layer embedded, the kinematic assumption is vital. In this paper, we systematically study the kinematic assumptions influence on the composite beam deflection and vibration characteristics. Based on the different kinematic assumptions, the equations of equilibrium/motion are different. Here three widely used kinematic assumptions are presented and the equations of equilibrium/motion are derived accordingly. As the three kinematic assumptions change from the simple to the complex one, the governing equations evolve from the linear to the nonlinear ones. For the nonlinear equations of equilibrium, the numerical solution is obtained by using Galerkin discretization method and Newton-Rhapson iteration method. The analysis on the numerical difficulty of using Galerkin method on the post-buckling analysis is presented. For the post-buckling analysis, finite element method is applied to avoid the difficulty due to the singularity occurred in Galerkin method. The natural frequencies of the composite beam with the nonlinear governing equation, which are obtained by directly linearizing the equations and locally linearizing the equations around each equilibrium, are compared. The influences of the SMA layer thickness and the shift from neutral axis on the deflection, buckling and post-buckling are also investigated. This paper presents a very general way to treat thermo-mechanical properties of the composite beam with SMA arbitrarily embedded. The governing equations for each kinematic assumption consist of a third order and a fourth order differential equation with a total of seven boundary conditions. Some previous studies on the SMA layer either ignore the thermal constraint

  14. Design and analysis of high-numerical-aperture beam shaping systems; Design und Analyse von Strahlformungssystemen hoher numerischer Apertur

    Energy Technology Data Exchange (ETDEWEB)

    Schweitzer, Hagen

    2009-11-24

    The generation of light tailored to measure stands today in the center of many innovative applications. A possibility of the flexible manipulation of light is the laser-beam shaping.Aim is thereby to transform the intensity profile of a laser beam to a wanted profile. The main topic of this thesis is the modeling and propagation of laser light in paraxial and non-paraxial beam-shaping systems as well as the optimization of these systems by means of a generalized projection algorithm. This algorithm is applied for the optimization by means of aspherical formula or polynomials point-by-point parametrized beam shaping surfaces. It is shown that during the optimization a regardment of diffraction, interference, and abberations is possible. The latter can not only be regarded, but directly used for the beam shaping. Finally it is shown that the aberrations of spherical catalogue lenses are already sufficient for some beam-shaping applications. The efficiency of the developed optimization algorithms is demonstrated both on paraxial and on non-paraxial beam-shaping examples with a numerical aperture of up to 0.62. Finally in the present thesis concepts for the achromatization and for the wave-length multiplexing are introduced, which are based on the application of diverse surfaces and materials with different dispersion. While the achromatization aims to make the optical function of a beam-shaping system wave-length independent, the wavelength multiplexing tries directly to realize different optical functions for diverse design wavelengths. [German] Die Erzeugung massgeschneiderten Lichts steht heute im Mittelpunkt vieler innovativer Anwendungen. Eine Moeglichkeit der flexiblen Manipulation von Licht ist die Laserstrahlformung. Ziel ist es dabei, das Intensitaetsprofil eines Laserstrahls in ein gewuenschtes Profil umzuformen. Schwerpunkt dieser Arbeit ist die Modellierung und Ausbreitung von Laserlicht in paraxialen und nicht-paraxialen Strahlformungssystemen sowie die

  15. Preliminary results of a prototype C-shaped PET designed for an in-beam PET system

    International Nuclear Information System (INIS)

    Kim, Hyun-Il; Chung, Yong Hyun; Lee, Kisung; Kim, Kyeong Min; Kim, Yongkwon; Joung, Jinhun

    2016-01-01

    Positron emission tomography (PET) can be utilized in particle beam therapy to verify the dose distribution of the target volume as well as the accuracy of the treatment. We present an in-beam PET scanner that can be integrated into a particle beam therapy system. The proposed PET scanner consisted of 14 detector modules arranged in a C-shape to avoid blockage of the particle beam line by the detector modules. Each detector module was composed of a 9×9 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals optically coupled to four 29-mm-diameter PMTs using the photomultiplier-quadrant-sharing (PQS) technique. In this study, a Geant4 Application for Tomographic Emission (GATE) simulation study was conducted to design a C-shaped PET scanner and then experimental evaluation of the proposed design was performed. The spatial resolution and sensitivity were measured according to NEMA NU2-2007 standards and were 6.1 mm and 5.61 cps/kBq, respectively, which is in good agreement with our simulation, with an error rate of 12.0%. Taken together, our results demonstrate the feasibility of the proposed C-shaped in-beam PET system, which we expect will be useful for measuring dose distribution in particle therapy.

  16. An analytical model for shape memory alloy fiber-reinforced composite thin-walled beam undergoing large deflection

    Directory of Open Access Journals (Sweden)

    Yongsheng Ren

    2015-03-01

    Full Text Available The structural model of the thin-walled laminated beams with integral shape memory alloy active fibers and accounting for geometrically nonlinear is presented in this article. The structural modeling is split into two parts: a two-dimensional analysis over the cross section and a geometrically nonlinear analysis of a beam along the beam span. The variational asymptotic method is used to formulate the force–deformation relationship equations taking into account the presence of active shape memory alloy fibers distributed along the cross section of the beam. The geometrically nonlinear governing equations are derived using variational principle and based on the von Kármán-type nonlinear strain–displacement relations. The equations are then solved using Galerkin’s method and an incremental Newton–Raphson method. The validation for the proposed model has been carried out by comparison of the present results with those available in the literature. The results show that significant extension, bending, and twisting coupled nonlinear deflections occur during the phase transformation due to shape memory alloy actuation. The effects of the volume fraction of the shape memory alloy fiber and ply angle are also addressed.

  17. Impact of phase errors at the conjugate step on the propagation of intensity and phase shaped laser beams

    CSIR Research Space (South Africa)

    Litvin, IA

    2007-01-01

    Full Text Available The authors investigate the phase conjugating element of a two element Fourier transform beam shaping scheme and the impact this element has on the resulting propagation. It is shown that there are stricter limitations placed on the system when...

  18. Bunch-shape monitor for a picosecond single-bunch beam of a 35 MeV electron linear accelerator

    International Nuclear Information System (INIS)

    Hosono, Yoneichi; Nakazawa, Masaharu; Iguchi, Tetsuo

    1995-01-01

    A non-interactive-type bunch-shape and beam intensity monitor for a 35 MeV electron linear accelerator (linac) has been developed. The monitor consists of an electric SMA-type connector and an Al pipe of 50 mm inner diameter. Test measurements of the present monitor have been made under the conditions of the accelerated charges of lower than 27 nC/pulse and the pulse width ranging from 6 to 30 ps (Full Width at Half Maximum). The results show that the present monitor is applicable to bunch-shape measurement of the picosecond single-bunch beam. The monitor output is also found to be proportional to the beam intensity of more than 0.05 nC/pulse. (author)

  19. Acceleration of on-axis and ring-shaped electron beams in wakefields driven by Laguerre-Gaussian pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guo-Bo [College of Science, National University of Defense Technology, Changsha 410073 (China); Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Min, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com; Luo, Ji; Zeng, Ming; Yuan, Tao; Yu, Ji-Ye; Yu, Lu-Le; Weng, Su-Ming [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); Ma, Yan-Yun, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com [College of Science, National University of Defense Technology, Changsha 410073 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); Yu, Tong-Pu [College of Science, National University of Defense Technology, Changsha 410073 (China); Sheng, Zheng-Ming [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2016-03-14

    The acceleration of electron beams with multiple transverse structures in wakefields driven by Laguerre-Gaussian pulses has been studied through three-dimensional (3D) particle-in-cell simulations. Under different laser-plasma conditions, the wakefield shows different transverse structures. In general cases, the wakefield shows a donut-like structure and it accelerates the ring-shaped hollow electron beam. When a lower plasma density or a smaller laser spot size is used, besides the donut-like wakefield, a central bell-like wakefield can also be excited. The wake sets in the center of the donut-like wake. In this case, both a central on-axis electron beam and a ring-shaped electron beam are simultaneously accelerated. Further, reducing the plasma density or laser spot size leads to an on-axis electron beam acceleration only. The research is beneficial for some potential applications requiring special pulse beam structures, such as positron acceleration and collimation.

  20. Improved passive shunt vibration control of smart piezo-elastic beams using modal piezoelectric transducers with shaped electrodes

    International Nuclear Information System (INIS)

    Vasques, C M A

    2012-01-01

    Modal control and spatial filtering technologies for mitigation of vibration and/or structural acoustics radiation may be achieved through the use of distributed modal piezoelectric transducers with properly shaped electrodes. This approach filters out undesirable and uncontrollable modes over the bandwidth of interest in order to increase the robustness and stability of the controlled structural system, and may also yield higher values of the generalized modal electromechanical coupling coefficient, which is an important design parameter for achieving efficient passive shunt damping design. In this paper the improvements in passive shunt damping performance when using modal piezoelectric transducers with shaped electrodes are investigated for a two-layered resonant-shunted piezo-elastic smart beam structure. An electromechanical one-dimensional equivalent single-layer Euler–Bernoulli analytical model of two-layered smart piezo-elastic beams with arbitrary spatially shaped electrodes is established for modal and uniform electrode designs. The model is verified and validated by comparison with a one-dimensional discrete-layer (layerwise) finite element model, the damping performance of the shunted smart beam with shaped electrodes is investigated and assessed in terms of the generalized electromechanical coupling coefficient and frequency responses obtained when considering uniform and modally shaped electrodes and the underlying improved performance and advantages are assessed and discussed. (paper)

  1. The use of intensity-modulated radiation therapy photon beams for improving the dose uniformity of electron beams shaped with MLC.

    Science.gov (United States)

    Mosalaei, Homeira; Karnas, Scott; Shah, Sheel; Van Doodewaard, Sharon; Foster, Tim; Chen, Jeff

    2012-01-01

    Electrons are ideal for treating shallow tumors and sparing adjacent normal tissue. Conventionally, electron beams are collimated by cut-outs that are time-consuming to make and difficult to adapt to tumor shape throughout the course of treatment. We propose that electron cut-outs can be replaced using photon multileaf collimator (MLC). Two major problems of this approach are that the scattering of electrons causes penumbra widening because of a large air gap, and available commercial treatment planning systems (TPSs) do not support MLC-collimated electron beams. In this study, these difficulties were overcome by (1) modeling electron beams collimated by photon MLC for a commercial TPS, and (2) developing a technique to reduce electron beam penumbra by adding low-energy intensity-modulated radiation therapy (IMRT) photons (4 MV). We used blocks to simulate MLC shielding in the TPS. Inverse planning was used to optimize boost photon beams. This technique was applied to a parotid and a central nervous system (CNS) clinical case. Combined photon and electron plans were compared with conventional plans and verified using ion chamber, film, and a 2D diode array. Our studies showed that the beam penumbra for mixed beams with 90 cm source to surface distance (SSD) is comparable with electron applicators and cut-outs at 100 cm SSD. Our mixed-beam technique yielded more uniform dose to the planning target volume and lower doses to various organs at risk for both parotid and CNS clinical cases. The plans were verified with measurements, with more than 95% points passing the gamma criteria of 5% in dose difference and 5 mm for distance to agreement. In conclusion, the study has demonstrated the feasibility and potential advantage of using photon MLC to collimate electron beams with boost photon IMRT fields. Copyright © 2012 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  2. Research of Effective Width of FRP U-shaped Hoop Reinforcement Properties of Concrete Beams by Shear

    Directory of Open Access Journals (Sweden)

    Li Baokun

    2015-01-01

    Full Text Available The paste fiber reinforced composite material (hereinafter referred to as FRP U-shaped hoop of reinforced concrete beams interfacial debonding is an important reinforcement technology research. For the effective width of the CFRP U-shaped hoop reinforcement, it is still a lack of in-depth research, only relying on the test research huge workload, this article (ANSYS and the numerical simulation in the whole process of the shear load release properties of finite element calculation software. According to the results of finite element analysis, the author studied the CFRP U-shaped hoop to increase the width of the shear capacity of reinforced concrete beams by the impact.

  3. A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy

    International Nuclear Information System (INIS)

    Jung An, Su; Beak, Cheol-Ha; Lee, Kisung; Hyun Chung, Yong

    2013-01-01

    The application of hadrons such as carbon ions is being developed for the treatment of cancer. The effectiveness of such a technique is due to the eligibility of charged particles in delivering most of their energy near the end of the range, called the Bragg peak. However, accurate verification of dose delivery is required since misalignment of the hadron beam can cause serious damage to normal tissue. PET scanners can be utilized to track the carbon beam to the tumor by imaging the trail of the hadron-induced positron emitters in the irradiated volume. In this study, we designed and evaluated (through Monte Carlo simulations) an in-beam PET scanner for monitoring patient dose in carbon beam therapy. A C-shaped PET and a partial-ring PET were designed to avoid interference between the PET detectors and the therapeutic carbon beam delivery. Their performance was compared with that of a full-ring PET scanner. The C-shaped, partial-ring, and full-ring scanners consisted of 14, 12, and 16 detector modules, respectively, with a 30.2 cm inner diameter for brain imaging. Each detector module was composed of a 13×13 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals and four round 25.4 mm diameter PMTs. To estimate the production yield of positron emitters such as 10 C, 11 C, and 15 O, a cylindrical PMMA phantom (diameter, 20 cm; thickness, 20 cm) was irradiated with 170, 290, and 350 AMeV 12 C beams using the GATE code. Phantom images of the three types of scanner were evaluated by comparing the longitudinal profile of the positron emitters, measured along the carbon beam as it passed a simulated positron emitter distribution. The results demonstrated that the development of a C-shaped PET scanner to characterize carbon dose distribution for therapy planning is feasible.

  4. Measuring contact angle and meniscus shape with a reflected laser beam.

    Science.gov (United States)

    Eibach, T F; Fell, D; Nguyen, H; Butt, H J; Auernhammer, G K

    2014-01-01

    Side-view imaging of the contact angle between an extended planar solid surface and a liquid is problematic. Even when aligning the view perfectly parallel to the contact line, focusing one point of the contact line is not possible. We describe a new measurement technique for determining contact angles with the reflection of a widened laser sheet on a moving contact line. We verified this new technique measuring the contact angle on a cylinder, rotating partially immersed in a liquid. A laser sheet is inclined under an angle φ to the unperturbed liquid surface and is reflected off the meniscus. Collected on a screen, the reflection image contains information to determine the contact angle. When dividing the laser sheet into an array of laser rays by placing a mesh into the beam path, the shape of the meniscus can be reconstructed from the reflection image. We verified the method by measuring the receding contact angle versus speed for aqueous cetyltrimethyl ammonium bromide solutions on a smooth hydrophobized as well as on a rough polystyrene surface.

  5. Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

    KAUST Repository

    Rawashdeh, E.; Karam, A.; Foulds, Ian G.

    2012-01-01

    This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

  6. Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

    KAUST Repository

    Rawashdeh, E.

    2012-07-06

    This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

  7. An analytical model of a curved beam with a T shaped cross section

    Science.gov (United States)

    Hull, Andrew J.; Perez, Daniel; Cox, Donald L.

    2018-03-01

    This paper derives a comprehensive analytical dynamic model of a closed circular beam that has a T shaped cross section. The new model includes in-plane and out-of-plane vibrations derived using continuous media expressions which produces results that have a valid frequency range above those available from traditional lumped parameter models. The web is modeled using two-dimensional elasticity equations for in-plane motion and the classical flexural plate equation for out-of-plane motion. The flange is modeled using two sets of Donnell shell equations: one for the left side of the flange and one for the right side of the flange. The governing differential equations are solved with unknown wave propagation coefficients multiplied by spatial domain and time domain functions which are inserted into equilibrium and continuity equations at the intersection of the web and flange and into boundary conditions at the edges of the system resulting in 24 algebraic equations. These equations are solved to yield the wave propagation coefficients and this produces a solution to the displacement field in all three dimensions. An example problem is formulated and compared to results from finite element analysis.

  8. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    International Nuclear Information System (INIS)

    Burlon, Alejandro A.; Valda, Alejandro A.; Girola, Santiago; Minsky, Daniel M.; Kreiner, Andres J.

    2010-01-01

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7 Li(p, n) 7 Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  9. Natural Frequencies and Mode Shapes of a Nonlinear, Uniform Cantilevered Beam

    National Research Council Canada - National Science Library

    Marquez-Chisolm, Daniel J

    2006-01-01

    A series of experiments in 1975, referred to as the Princeton Beam Experiments, were performed to measure natural frequencies and create a nonlinear elastic deformation model to improve helicopter main beam designs...

  10. Natural Frequencies and Mode Shapes of a Nonlinear, Uniform Cantilevered Beam

    National Research Council Canada - National Science Library

    Marquez-Chisolm, Daniel J

    2006-01-01

    .... These experiments used a homogeneous 7075 aluminum beam and have been referenced as a baseline for the past thirty years to validate computer models and theories in an effort to build beams capable...

  11. Damage identification of beam structures using free response shapes obtained by use of a continuously scanning laser Doppler vibrometer system

    Science.gov (United States)

    Xu, Y. F.; Chen, Da-Ming; Zhu, W. D.

    2017-08-01

    Spatially dense operating deflection shapes and mode shapes can be rapidly obtained by use of a continuously scanning laser Doppler vibrometer (CSLDV) system, which sweeps its laser spot over a vibrating structure surface. This paper introduces a new type of vibration shapes called a free response shape (FRS) that can be obtained by use of a CSLDV system, and a new damage identification methodology using FRSs is developed for beam structures. An analytical expression of FRSs of a damped beam structure is derived, and FRSs from the analytical expression compare well with those from a finite element model. In the damage identification methodology, a free-response damage index (FRDI) is proposed, and damage regions can be identified near neighborhoods with consistently high values of FRDIs associated with different modes; an auxiliary FRDI is defined to assist identification of the neighborhoods. A FRDI associated with a mode consists of differences between curvatures of FRSs associated with the mode in a number of half-scan periods of a CSLDV system and those from polynomials that fit the FRSs with properly determined orders. A convergence index is proposed to determine the proper order of a polynomial fit. One advantage of the methodology is that the FRDI does not require any baseline information of an undamaged beam structure, if it is geometrically smooth and made of materials that have no stiffness and mass discontinuities. Another advantage is that FRDIs associated with multiple modes can be obtained using free response of a beam structure measured by a CSLDV system in one scan. The number of half-scan periods for calculation of the FRDI associated with a mode can be determined by use of the short-time Fourier transform. The proposed methodology was numerically and experimentally applied to identify damage in beam structures; effects of the scan frequency of a CSLDV system on qualities of obtained FRSs were experimentally investigated.

  12. Into the development of a model to assess beam shaping and polarization control effects on laser cutting

    Science.gov (United States)

    Rodrigues, Gonçalo C.; Duflou, Joost R.

    2018-02-01

    This paper offers an in-depth look into beam shaping and polarization control as two of the most promising techniques for improving industrial laser cutting of metal sheets. An assessment model is developed for the study of such effects. It is built upon several modifications to models as available in literature in order to evaluate the potential of a wide range of considered concepts. This includes different kinds of beam shaping (achieved by extra-cavity optical elements or asymmetric diode staking) and polarization control techniques (linear, cross, radial, azimuthal). A fully mathematical description and solution procedure are provided. Three case studies for direct diode lasers follow, containing both experimental data and parametric studies. In the first case study, linear polarization is analyzed for any given angle between the cutting direction and the electrical field. In the second case several polarization strategies are compared for similar cut conditions, evaluating, for example, the minimum number of spatial divisions of a segmented polarized laser beam to achieve a target performance. A novel strategy, based on a 12-division linear-to-radial polarization converter with an axis misalignment and capable of improving cutting efficiency with more than 60%, is proposed. The last case study reveals different insights in beam shaping techniques, with an example of a beam shape optimization path for a 30% improvement in cutting efficiency. The proposed techniques are not limited to this type of laser source, neither is the model dedicated to these specific case studies. Limitations of the model and opportunities are further discussed.

  13. Tuneable Gaussian to flat-top resonator by amplitude beam shaping using a digital laser

    CSIR Research Space (South Africa)

    Ngcobo, S

    2014-02-01

    Full Text Available In this paper we experimentally demonstrate a simple laser cavity that produces spatial tuneable laser modes from a Gaussian beam to a Flat-top beam and a Donut-beam. The laser cavity contains an opaque ring and an adjustable circular aperture...

  14. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, M; Li, R; Xing, L [Stanford UniversitySchool of Medicine, Stanford, CA (United States); Ye, Y [Stanford Univ, Management Science and Engineering, Stanford, Ca (United States); Boyd, S [Stanford University, Electrical Engineering, Stanford, CA (United States)

    2014-06-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  15. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    International Nuclear Information System (INIS)

    Zarepisheh, M; Li, R; Xing, L; Ye, Y; Boyd, S

    2014-01-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  16. The potential for optical beam shaping of UV laser sources for mass scale quarantine disinfection applications

    Science.gov (United States)

    Lizotte, Todd

    2010-08-01

    disinfection systems using high intensity UV laser sources instead of UV bulb techniques by using laser beam shaping optics in conjunction with traditional optical laser beam delivery techniques.

  17. Effect of beam condition in variable-shaped electron-beam direct writing for 0.25 μm and below

    International Nuclear Information System (INIS)

    Hirasawa, S.; Nakajima, K.; Tamura, T.; Aizaki, N.

    1993-01-01

    The effect of incident electron-beam conditions, which are acceleration voltage and beam blur of variable-shaped electron-beam direct writing, is investigated using the deposited energy distribution to realize a fine pattern of ≤0.25 μm in trilayer resist process. The deposited energy distribution is calculated using a three-dimensional Monte Carlo method. In a trilayer resist system, a thin bottom resist layer can be used, because the contrast value derived from the Monte Carlo calculation is independent of the bottom layer thickness. The beam blur of 0.05 μm does not degrade 0.25 μm line-and-space (L/S) patterns, but seriously degrades 0.1 μm L/S patterns. Higher acceleration voltage is effective for improving the contrast. At lower acceleration voltage, the slope of the deposited energy profile defined at the resist bottom is mainly influenced by electron scattering. On the other hand, at higher acceleration voltage, the slope of deposited energy profile mainly depends on the beam blur. The 0.1 μm L/S patterns are expected to be resolved at 30 kV when there is less than 0.02 μm beam blur with trilayer resist system. The possibility of using a single layer resist process for 0.1 μm L/S pattern will be barely realized at the conditions of 50 kV and 0.02 μm beam blur

  18. Beam shaping of laser diode radiation by waveguides with arbitrary cladding geometry written with fs-laser radiation.

    Science.gov (United States)

    Beckmann, Dennis; Schnitzler, Daniel; Schaefer, Dagmar; Gottmann, Jens; Kelbassa, Ingomar

    2011-12-05

    Waveguides with arbitrary cross sections are written in the volume of Al(2)O(3)-crystals using tightly focused femtosecond laser radiation. Utilizing a scanning system with large numerical aperture, complex cladding geometries are realized with a precision around 0.5 µm and a scanning speed up to 100 mm/s. Individual beam and mode shaping of laser diode radiation is demonstrated by varying the design of the waveguide cladding. The influence of the writing parameters on the waveguide properties are investigated resulting in a numerical aperture of the waveguides in the range of 0.1. This direct laser writing technique enables optical devices which could possibly replace bulky beam shaping setups with an integrated solution.

  19. Beam shaping for multicolour light-emitting diodes with diffractive optical elements

    KAUST Repository

    Yu, Chao; Peng, Yifan; Guo, Tianyi; Fu, Qiang; Li, Haifeng; Liu, Xu

    2016-01-01

    in the algorithm to achieve better and identical shaping performance for multiple colours. Accordingly, a DOE for shaping light from green and blue LEDs has been designed and fabricated. Both experiment and numerical simulations have been conducted and the results

  20. Evaluation of imaging reformation with cone beam computed tomography for the assessment of bone density and shape in mandible

    International Nuclear Information System (INIS)

    Hong, Sang Woo; Kim, Gyu Tae; Choi, Yong Suk; Hwan, Eui Hwan

    2008-01-01

    Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. The change of inferior border of mandible and anterior border of ramous in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase was not reproduced at cone beam computed tomography compared with soft x-ray radiography. CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images' property.

  1. Spatial Control of Photoemitted Electron Beams using a Micro-Lens-Array Transverse-Shaping Technique

    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, A. [Northern Illinois U.; Qiang, G. [Tsinghua U., Beijing, Dept. Eng. Phys.; Ha, G. [POSTECH; Wisniewski, E. [Argonne (main); Piot, P. [NIU, DeKalb; Power, J. G. [Argonne (main); Gai, W. [Argonne (main)

    2017-07-24

    A common issue encountered in photoemission electron sources used in electron accelerators is the transverse inhomogeneity of the laser distribution resulting from the laser-amplification process and often use of frequency up conversion in nonlinear crystals. A inhomogeneous laser distribution on the photocathode produces charged beams with lower beam quality. In this paper, we explore the possible use of microlens arrays (fly-eye light condensers) to dramatically improve the transverse uniformity of the drive laser pulse on UV photocathodes. We also demonstrate the use of such microlens arrays to generate transversely-modulated electron beams and present a possible application to diagnose the properties of a magnetized beam.

  2. Combining Generalized Phase Contrast with matched filtering into a versatile beam shaping approach

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    2010-01-01

    We adapt concepts from matched filtering to propose a method for generating reconfigurable multiple beams. Combined with the Generalized Phase Contrast (GPC) technique, the proposed method coined mGPC can yield dynamically reconfigurable optical beam arrays with high light efficiency for optical...... manipulation, high-speed sorting and other parallel spatial light applications [1]....

  3. Tuneable Gaussian to flat-top resonator by amplitude beam shaping

    CSIR Research Space (South Africa)

    Ngcobo, S

    2013-09-01

    Full Text Available We outline a simple laser cavity comprising an opaque ring and a circular aperture that is capable of producing spatially tuneable laser modes, from a Gaussian beam to a Flat-top beam. The tuneability is achieved by varying the diameter...

  4. Shear or bending? Experimental results on large t-shaped prestressed conrete beams

    NARCIS (Netherlands)

    Ensink, S.W.H.; Van der Veen, C.; De Boer, A.

    2015-01-01

    Experimental results of four shear tests on two large prestressed concrete beams are compared to nonlinear analysis and design code calculations. The beams have a length of 12 m and a depth of 1.3 m and are reinforced with stirrups and pre-tensioning. The four tests consist of a single point load at

  5. Tailoring the laser pulse shape to improve the quality of the self-injected electron beam in laser wakefield acceleration

    International Nuclear Information System (INIS)

    Upadhyay, Ajay K.; Samant, Sushil A.; Krishnagopal, S.

    2013-01-01

    In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement in the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.

  6. Numerical analysis of dynamic behavior of pre-stressed shape memory alloy concrete beam-column joints

    Science.gov (United States)

    Yan, S.; Xiao, Z. F.; Lin, M. Y.; Niu, J.

    2018-04-01

    Beam-column joints are important parts of a main frame structure. Mechanical properties of beam-column joints have a great influence on dynamic performances of the frame structure. Shape memory alloy (SMA) as a new type of intelligent metal materials has wide applications in civil engineering. The paper aims at proposing a novel beam-column joint reinforced with pre-stressed SMA tendons to increase its dynamic performance. Based on the finite element analysis (FEA) software ABAQUS, a numerical simulation for 6 beam-column scaled models considering different SMA reinforcement ratios and pre-stress levels was performed, focusing on bearing capacities, energy-dissipation and self-centering capacities, etc. These models were numerically tested under a pseudo-static load on the beam end, companying a constant vertical compressive load on the top of the column. The numerical results show that the proposed SMA-reinforced joint has a significantly increased bearing capacity and a good self-centering capability after unloading even though the energy-dissipation capacity becomes smaller due the less residual deformation. The concept and mechanism of the novel joint can be used as an important reference for civil engineering applications.

  7. Structural aspects of cold-formed steel section designed as U-shape composite beam

    Science.gov (United States)

    Saggaff, Anis; Tahir, Mahmood Md.; Azimi, Mohammadamin; Alhajri, T. M.

    2017-11-01

    Composite beam construction usually associated with old-style Hot-Rolled Steel Section (HRSS) has proven to act much better in compare with Cold-Formed Steel Section (CFSS) sections due to thicker section. Due, it's getting popular to replace HRSS with CFSS in some aspects as a composite beam. The advantages such as lightweight, cost effective and easy to install have contributed to the apply CFSS as a preferred construction material for composite beam. There is a few technical data available regarding the application of the usage of CFSS as a composite system, despite the potentials use for residential and light-weight industrial constructions. This paper presents an experimental tests results which have been conducted using CFSS as composite beam. Composite action of CFSS arranged as double beam with Self-Compacting Concrete (SCC) slab are integrated together with bolted shear connectors were used. A full-scale test comprised of 3 proposed composite beam specimens with bolted shear connector spaced at 300 mm interval of grade 8.8 was using single nut with washer on flange of CFS, cast to the slab and loaded until failed. The test show that the bolted shear connector yielded better capacity of ultimate strength and ultimate moment for the proposed composite beam. It can be concluded that, bolted shear connectors of 16 mm in diameter performed better than the other diameter size of bolted shear connectors.

  8. Spatial beam shaping using a micro-structured optical fiber and all-fiber laser amplification system for large-scale laser facilities seeding

    International Nuclear Information System (INIS)

    Calvet, Pierre

    2014-01-01

    Spatial beam shaping is an important topic for the lasers applications. For various industrial areas (marking, drilling, laser-matter interaction, high-power laser seeding...) the optical beam has to be flattened. Currently, the state of the art of the beam shaping: 'free-space' solutions or highly multimode fibers, are not fully suitable. The first ones are very sensitive to any perturbations and the maintenance is challenging, the second ones cannot deliver a coherent beam. For this reason, we present in this manuscript a micro-structured optical single-mode fiber delivering a spatially flattened beam. This 'Top-Hat' fiber can shape any beam in a spatially coherent beam what is a progress with respect to the highly multimode fibers used in the state of the art. The optical fibers are easy to use and very robust, what is a strong benefit with respect to the 'free-space' solutions. Thanks to this fiber, we could realize an all-fiber multi-stage laser chain to amplify a 10 ns pulse to 100 μJ. Moreover the temporal, spectral and spatial properties were preserved. We adapted this 'Top-Hat' fiber to this multi-stage laser chain, we proved the capability and the interest of this fiber for the spatial beam shaping of the laser beams in highly performing and robust laser systems. (author) [fr

  9. Effect of material acoustic anisotropy on the shape of ultrasonic wave beam

    International Nuclear Information System (INIS)

    Iotchev, B.; Pawlowski, Z.

    1976-01-01

    When ultrasonic waves propagate in some types of materials having a structural anisotropy, a distortion of the ultrasonic beam takes place. This phenomenon is the cause of errors in the determination of flaw location and size

  10. Evaluation of fiber’s misorientation effect on compliance and load carry capacity of shaped composite beams

    Science.gov (United States)

    Polilov, A. N.; Tatus’, N. A.

    2018-04-01

    The goal of this paper is analysis of design methods for composite beams and plates with curvilinear fiber trajectories. The novelty of this approach is determined by the fact that traditional composite materials are typically formed using prepregs with rectilinear fibers only. The results application area is associated with design process for shaped composite structure element by using of biomechanical principles. One of the related problems is the evaluation of fiber’s misorientation effect on stiffness and load carry capacity of shaped composite element with curvilinear fiber trajectories. Equistrong beam with constant cross-section area is considered as example, and it can be produced by unidirectional fiber bunch forming, impregnated with polymer matrix. Effective elastic modulus evaluation methods for structures with curvilinear fiber trajectories are validated. Misorientation angle range (up to 5o) when material with required accuracy can be considered as homogeneous, neglecting fiber misorientation, is determined. It is shown that for the beams with height-to-width ratio small enough it is possible to consider 2D misorientation only.

  11. Vibration attenuation and shape control of surface mounted, embedded smart beam

    Directory of Open Access Journals (Sweden)

    Vivek Rathi

    Full Text Available Active Vibration Control (AVC using smart structure is used to reduce the vibration of a system by automatic modification of the system structural response. AVC is widely used, because of its wide and broad frequency response range, low additional mass, high adaptability and good efficiency. A lot of research has been done on Finite Element (FE models for AVC based on Euler Bernoulli Beam Theory (EBT. In the present work Timoshenko Beam Theory (TBT is used to model a smart cantilever beam with surface mounted sensors / actuators. A Periodic Output Feedback (POF Controller has been designed and applied to control the first three modes of vibration of a flexible smart cantilever beam. The difficulties encountered in the usage of surface mounted piezoelectric patches in practical situations can be overcome by the use of embedded shear sensors / actuators. A mathematical model of a smart cantilever beam with embedded shear sensors and actuators is developed. A POF Controller has been designed and applied to control of vibration of a flexible smart cantilever beam and effect of actuator location on the performance of the controller is investigated. The mathematical modeling and control of a Multiple Input multiple Output (MIMO systems with two sensors and two actuators have also been considered.

  12. Wide variety of flower-color and -shape mutants regenerated from leaf cultures irradiated with ion beams

    International Nuclear Information System (INIS)

    Okamura, M.; Yasuno, N.; Ohtsuka, M.; Tanaka, A.; Shikazono, N.; Hase, Y.

    2003-01-01

    The efficiency of ion-beam irradiation combined with tissue culture in obtaining floral mutants was investigated and compared with those of gamma rays and X-rays in carnation. Leaf segments of carnation plants in vitro were irradiated with the 220 MeV carbon ions, and cultured till the shoot regenerated. The carbon ion had the highest effect in reducing the regeneration frequency, and the RBE value with respect to gamma-rays was four. The higher mutation frequency and the wider mutation spectrum were obtained in plants irradiated with the carbon ions than low LET radiations. Three new carnation varieties developed by ion-beam irradiation were applied for the registration of the Japanese Ministry of Agriculture, Forestry and Fisheries. The results indicate that ion beam irradiation could induce wide variety of flower-color and -shape mutants, and that the combined method of ion-beam irradiation with tissue culture is useful to obtain the commercial varieties in a short time

  13. Xenon focused ion beam in the shape memory alloys investigation – the case of NiTi and CoNiAl

    Czech Academy of Sciences Publication Activity Database

    Kopeček, Jaromír; Jurek, Karel; Kopecký, Vít; Klimša, Ladislav; Seiner, Hanuš; Sedlák, Petr; Landa, Michal; Dluhoš, J.; Petrenec, M.; Hladík, L.; Doupal, A.; Heczko, Oleg

    2014-01-01

    Roč. 20, Aug (2014), s. 335-336 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:68378271 ; RVO:61388998 Keywords : scanning electron microscope * SEM * focused ion beam * FIB * xenon plasma focused ion beam * dual beam * shape memory alloy * SMA Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.877, year: 2014

  14. SU-G-TeP1-04: Deriving Spot Shape Criteria for Proton Pencil Beam Scanning

    International Nuclear Information System (INIS)

    Wulff, J; Huggins, A

    2016-01-01

    Purpose: The shape of a single beam in proton PBS influences the resulting dose distribution. Spot profiles are modelled as two-dimensional Gaussian (single/ double) distributions in treatment planning systems (TPS). Impact of slight deviations from an ideal Gaussian on resulting dose distributions is typically assumed to be small due to alleviation by multiple Coulomb scattering (MCS) in tissue and superposition of many spots. Quantitative limits are however not clear per se. Methods: A set of 1250 deliberately deformed profiles with sigma=4 mm for a Gaussian fit were constructed. Profiles and fit were normalized to the same area, resembling output calibration in the TPS. Depth-dependent MCS was considered. The deviation between deformed and ideal profiles was characterized by root-mean-squared deviation (RMSD), skewness/ kurtosis (SK) and full-width at different percentage of maximum (FWxM). The profiles were convolved with different fluence patterns (regular/ random) resulting in hypothetical dose distributions. The resulting deviations were analyzed by applying a gamma-test. Results were compared to measured spot profiles. Results: A clear correlation between pass-rate and profile metrics could be determined. The largest impact occurred for a regular fluence-pattern with increasing distance between single spots, followed by a random distribution of spot weights. The results are strongly dependent on gamma-analysis dose and distance levels. Pass-rates of >95% at 2%/2 mm and 40 mm depth (=70 MeV) could only be achieved for RMSD<10%, deviation in FWxM at 20% and root of quadratic sum of SK <0.8. As expected the results improve for larger depths. The trends were well resembled for measured spot profiles. Conclusion: All measured profiles from ProBeam sites passed the criteria. Given the fact, that beam-line tuning can result shape distortions, the derived criteria represent a useful QA tool for commissioning and design of future beam-line optics.

  15. Design Oriented Model for the Assessment of T-Shaped Beam-Column Joints in Reinforced Concrete Frames

    Directory of Open Access Journals (Sweden)

    Antonio Bossio

    2017-12-01

    Full Text Available Beam-column joints represent very important elements of reinforced concrete (RC structures. In fact, beams and columns, at the boundary, generate internal forces acting on concrete core and on reinforcement bars with a very high gradient. To fully understand the seismic performances and the failure modes of T-shaped beam-column joints (external corner-positioned in RC structures, a simplified analytical model of joint behaviour is proposed and theoretical simulations have been performed. The model is based on the solution of a system of equilibrium equations of cracked joint portions designed to evaluate internal stresses at different values of column shear forces. The main aim of the proposed model is to identify the strength hierarchy. Limit values of different internal stresses allow us to detect the occurrence of different failure modes (namely the failure of the cracked joint, the bond failure of passing through bars, and the flexural/shear failures of columns or beams associated with column shear forces; the smaller one represents the capacity of the joint. The present work, focusing on T-shaped joints, could represent a useful tool for designers to quantify the performance of new structures or of existing ones. In fact, such a tool allows us to push an initial undesired failure mode to a more appropriate one to be evaluated. Finally, some experimental results of tests available in literature are reported, analysed, and compared to the predictions of the proposed model (by means of a worked example and of some international codes. The outcomes confirm that failure modes and corresponding joint capacities require an analytical model, like the proposed one, to be accurately predicted.

  16. Indirect intelligent sliding mode control of a shape memory alloy actuated flexible beam using hysteretic recurrent neural networks

    International Nuclear Information System (INIS)

    Hannen, Jennifer C; Buckner, Gregory D; Crews, John H

    2012-01-01

    This paper introduces an indirect intelligent sliding mode controller (IISMC) for shape memory alloy (SMA) actuators, specifically a flexible beam deflected by a single offset SMA tendon. The controller manipulates applied voltage, which alters SMA tendon temperature to track reference bending angles. A hysteretic recurrent neural network (HRNN) captures the nonlinear, hysteretic relationship between SMA temperature and bending angle. The variable structure control strategy provides robustness to model uncertainties and parameter variations, while effectively compensating for system nonlinearities, achieving superior tracking compared to an optimized PI controller. (paper)

  17. Emittance control of a beam by shaping the transverse charge distribution, using a tomography diagnostic

    International Nuclear Information System (INIS)

    Yakimenko, V.; Babzien, M.; Ben-Zvi, I.; Malone, R.; Wang, X.J.

    1998-06-01

    A high-brightness beam is very important for many applications. A diagnostic that measures the multi-dimensional phase-space density-distribution of the electron bunch is a must for obtaining such beams. Measurement of a slice emittance has been achieved. Tomographic reconstruction of phase space was suggested and implemented using a single quadrupole scan. In the present work the authors give special attention to the accuracy of the phase space reconstruction and present an analysis using a transport line with nine focusing magnets and techniques to control the optical functions and phases. This diagnostic, coupled with control of the radial charge distribution of presents an opportunity to improve the beam brightness. Combining the slice emittance and tomography diagnostics lead to an unprecedented visualization of phase space distributions in 5 dimensional phase-space and an opportunity to perform high-order emittance corrections

  18. Tuning the shape and damage in ion-beam induced ripples on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Biermanns, Andreas; Pietsch, Ullrich [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany); Hanisch, Antje; Grenzer, Joerg [Helmholtz-Zentrum Dresden-Rossendorf, Institut fuer Ionenstrahlphysik und Materialforschung, P.O. Box 510119, 01314 Dresden (Germany); Metzger, Till Hartmut [ESRF, 6 rue Jules Horowitz, BP220, 38043 Grenoble Cedex (France)

    2011-11-15

    We investigate the influence of ion beam parameters on the ripple formation on Si(001) surfaces after bombardment with Xe{sup +} ions of 25 keV kinetic energy using a scanning ion beam system. By combining grazing incidence X-ray diffraction, small angle scattering and X-ray reflectivity, we show that during ion irradiation with 70 off-normal angle of incidence, changing the size of the irradiated area leads to an increased number of defects at the interface towards crystalline material. At 65 angle of incidence, the ripple amplitude grows. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. 40 keV Shaped electron beam lithography for LIGA intermediate mask fabrication

    NARCIS (Netherlands)

    Luttge, R.; Adam, D.; Burkhardt, F.; Hoke, F.; Schacke, H.; Schmidt, M.; Wolf, H.; Schmidt, A.

    1999-01-01

    High precision LIGA masks require a soft X-ray pattern transfer from intermediate masks by means of electron beam lithography. Such a process has been realized using an upgraded Leica ZBA 23 machine with an acceleration voltage of 40 kV. Three process variations of the developer system, so called GG

  20. Laser beam welding of titanium nitride coated titanium using pulse-shaping

    Directory of Open Access Journals (Sweden)

    Milton Sergio Fernandes de Lima

    2005-09-01

    Full Text Available A new welding method which allows the assembly of two titanium nitride coated titanium parts is proposed. The welding procedure utilizes the possibility for pulse-shaping in order to change the energy distribution profile during the laser pulse. The pulse-shaping is composed of three elements: a a short high power pulse for partial ablation at the surface; b a long pulse for thermal penetration; and c a quenching slope for enhanced weldability. The combination of these three elements produces crack-free welds. The weld microstructure is changed in comparison to normal welding, i.e. with a rectangular pulse, as the nitrogen and the microhardness are more homogenously distributed in the weld under pulse-shaping conditions. This laser pulse dissolves the TiN layer and allows nitrogen to diffuse into the melt pool, also contributing to an enhanced weldability by providing suitable thermal conditions.

  1. Monitoring system of energy characteristics of electron beam during shaping process of power bremsstrahlung pulses

    International Nuclear Information System (INIS)

    Mordasov, N.G.; Ulimov, V.N.; Bryksin, V.A.; Shiyan, V.D.

    2005-01-01

    One proposes a procedure and a device to monitor dynamic and integral characteristics of electron power beams of high-current pulsed accelerators (HCPA) operating under Bremsstrahlung radiation mode. One obtained static and dynamic transfer characteristics for various types of heterogenous targets-converters under operation of UIN-10 HCPA with up to 4 MeV energy electrons, up to 60 kA current and 6 x 10 -8 -2 x 10 -6 s pulse efficient duration. One demonstrated the capabilities of the complex diagnostics of acceleration of electron beams by HCPA with simultaneous determination of parameters of the Bremsstrahlung radiation at the local point of the field behind the target-converter [ru

  2. The effect of customized beam shaping on normal tissue complications in radiation therapy of parotid gland tumors

    International Nuclear Information System (INIS)

    Keus, R.; Boer, R. de; Lebesque, J.; Noach, P.

    1991-01-01

    The impact of customized beam shaping was studied for 5 patients with parotid tumors treated with a paired wedged field technique. For each patient 2 plans were generated. The standard plan had unblocked portals with field sizes defined by the largest target contour found in any CT slice. In the 2nd plan customized beam's view (BEV) designed blocks were added to both beams. The differences in those distributions between the 2 types of plans were evaluated using dose-volume histograms (DVH). As expected, the dose distribution within the target volume showed no difference. However, a considerable sparing of normal tissue was observed for the plans with customized blocks. The volume of un-necessary exposed normal tissue that received more than 90 percent of the prescribed dose, was reduced by a factor of about 4: from 165 to 44 percent on an average, if the volume is expressed as a percentage of the target volume in each patient. In particular, the homolateral mandible showed a mean decrease of 21 percent of integral dose when blocks were used. Normal tissue complication probabilities (NTCP) were calculated. For a tumor dose of 70 Gy, the average bone necrosis probability was reduced from 8.4 percent (no blocks) to 4.1. percent (blocks). For other normal tissues such as nervous tissue, other soft tissues and bones a substantial reduction of integral dose was found for al patients when individual blocks were used. (author). 10 refs.; 4 figs.; 2 tabs

  3. Optimization of beam shaping assembly based on D-T neutron generator and dose evaluation for BNCT

    Science.gov (United States)

    Naeem, Hamza; Chen, Chaobin; Zheng, Huaqing; Song, Jing

    2017-04-01

    The feasibility of developing an epithermal neutron beam for a boron neutron capture therapy (BNCT) facility based on a high intensity D-T fusion neutron generator (HINEG) and using the Monte Carlo code SuperMC (Super Monte Carlo simulation program for nuclear and radiation process) is proposed in this study. The Monte Carlo code SuperMC is used to determine and optimize the final configuration of the beam shaping assembly (BSA). The optimal BSA design in a cylindrical geometry which consists of a natural uranium sphere (14 cm) as a neutron multiplier, AlF3 and TiF3 as moderators (20 cm each), Cd (1 mm) as a thermal neutron filter, Bi (5 cm) as a gamma shield, and Pb as a reflector and collimator to guide neutrons towards the exit window. The epithermal neutron beam flux of the proposed model is 5.73 × 109 n/cm2s, and other dosimetric parameters for the BNCT reported by IAEA-TECDOC-1223 have been verified. The phantom dose analysis shows that the designed BSA is accurate, efficient and suitable for BNCT applications. Thus, the Monte Carlo code SuperMC is concluded to be capable of simulating the BSA and the dose calculation for BNCT, and high epithermal flux can be achieved using proposed BSA.

  4. Multiple beam interference lithography: A tool for rapid fabrication of plasmonic arrays of arbitrary shaped nanomotifs

    Czech Academy of Sciences Publication Activity Database

    Vala, Milan; Homola, Jiří

    2016-01-01

    Roč. 24, č. 14 (2016), s. 15656-15665 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GBP205/12/G118 Grant - others:AV ČR(CZ) AP1101 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:67985882 Keywords : displacement talbot lithography * noncoplanar beams * large areas Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.307, year: 2016

  5. Investigation into the optimum beam shape and fluence for selective ablation of dental calculus at lambda = 400 nm.

    Science.gov (United States)

    Schoenly, Joshua E; Seka, Wolf; Rechmann, Peter

    2010-01-01

    A frequency-doubled Ti:sapphire laser is shown to selectively ablate dental calculus. The optimal transverse shape of the laser beam, including its variability under water-cooling, is determined for selective ablation of dental calculus. Intensity profiles under various water-cooling conditions were optically observed. The 400-nm laser was coupled into a multimode optical fiber using an f = 2.5-cm lens and light-shaping diffuser. Water-cooling was supplied coaxially around the fiber. Five human tooth samples (four with calculus and one pristine) were irradiated perpendicular to the tooth surface while the tooth was moved back and forth at 0.3 mm/second, varying between 20 and 180 iterations. The teeth were imaged before and after irradiation using light microscopy with a flashing blue light-emitting diode (LED). An environmental scanning electron microscope imaged each tooth after irradiation. High-order super-Gaussian intensity profiles are observed at the output of a fiber coiled around a 4-in. diameter drum. Super-Gaussian beams have a more-homogenous fluence distribution than Gaussian beams and have a higher energy efficiency for selective ablation. Coaxial water-cooling does not noticeably distort the intensity distribution within 1 mm from the optical fiber. In contrast, lasers focused to a Gaussian cross section (Calculus is preferentially ablated at high fluences (> or =2 J/cm(2)); below this fluence, stalling occurs because of photo-bleaching of the calculus. Healthy dental hard tissue is not removed at fluences calculus with a frequency-doubled Ti:sapphire laser. Fluences over 2 J/cm(2) are required to remove calculus efficiently since photo-bleaching stalls calculus removal below that value.

  6. Pattern generation using axicon lens beam shaping in two-photon polymerisation

    International Nuclear Information System (INIS)

    Bhuian, B.; Winfield, R.J.; O'Brien, S.; Crean, G.M.

    2007-01-01

    The fabrication of three-dimensional microstructures by two-photon polymerisation has been widely reported as a viable route to the development of photonic crystals, rotors, bridges and other complex artefacts requiring nanoscale resolution. Conventionally, single point serial writing is used to write the structures but recently multipoint beam delivery using beam division optics has been reported as a method of introducing parallel processing. In this paper we present an alternative and novel approach using an axicon lens to give profiled beam delivery. This enables complete three-dimensional annular structure fabrication without the use of scanning stages. In addition, the concept of axicon delivery is developed further to investigate three-dimensional structure as a function of axicon geometry. A Ti:sapphire laser, with wavelength 795 nm, 80 MHz repetition rate, 100 fs pulse duration and an average power of 700 mW, was used to initiate two-photon polymerisation. The axicon was used, in combination with a 100x microscope objective, to form representative three-dimensional structures based on the annular cell with varying diameter. The structures were written in a Zr-loaded resin prepared on a glass substrate using dip coating deposition of a Zr/PMMA hybrid prepared by the sol-gel method. Annuli with diameters up to 50 μm were characterised in terms of topography and surface roughness using SEM and Zygo interferometer. The writing technique was also extended to fabrication of stacked structures

  7. X-ray beam-shaping via deformable mirrors: surface profile and point spread function computation for Gaussian beams using physical optics.

    Science.gov (United States)

    Spiga, D

    2018-01-01

    X-ray mirrors with high focusing performances are commonly used in different sectors of science, such as X-ray astronomy, medical imaging and synchrotron/free-electron laser beamlines. While deformations of the mirror profile may cause degradation of the focus sharpness, a deliberate deformation of the mirror can be made to endow the focus with a desired size and distribution, via piezo actuators. The resulting profile can be characterized with suitable metrology tools and correlated with the expected optical quality via a wavefront propagation code or, sometimes, predicted using geometric optics. In the latter case and for the special class of profile deformations with monotonically increasing derivative, i.e. concave upwards, the point spread function (PSF) can even be predicted analytically. Moreover, under these assumptions, the relation can also be reversed: from the desired PSF the required profile deformation can be computed analytically, avoiding the use of trial-and-error search codes. However, the computation has been so far limited to geometric optics, which entailed some limitations: for example, mirror diffraction effects and the size of the coherent X-ray source were not considered. In this paper, the beam-shaping formalism in the framework of physical optics is reviewed, in the limit of small light wavelengths and in the case of Gaussian intensity wavefronts. Some examples of shaped profiles are also shown, aiming at turning a Gaussian intensity distribution into a top-hat one, and checks of the shaping performances computing the at-wavelength PSF by means of the WISE code are made.

  8. Shape evolution of nanostructures by thermal and ion beam processing. Modeling and atomistic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Roentzsch, L.

    2007-07-01

    Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven evolution). With these prospects and challenges at hand, formation and shape transformation of single-crystalline nanostructures due to the system-inherent capillary force in combination with external fields or forces are investigated in the frame of this dissertation by means of atomistic computer simulations. For the exploration (search, description, and prediction) of reaction pathways of nanostructure shape transformations, kinetic Monte Carlo (KMC) simulations are the method of choice. Since the employed KMC code is founded on a cellular automaton principle, the spatio-temporal development of lattice-based N-particle systems (N up to several million) can be followed for time spans of several orders of magnitude, while considering local phenomena due to atomic-scale effects like diffusion, nucleation, dissociation, or ballistic displacements. In this work, the main emphasis is put on nanostructures which have a cylindrical geometry, for example, nanowires (NWs), nanorods, nanotubes etc

  9. Shape evolution of nanostructures by thermal and ion beam processing. Modeling and atomistic simulations

    International Nuclear Information System (INIS)

    Roentzsch, L.

    2007-01-01

    Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven evolution). With these prospects and challenges at hand, formation and shape transformation of single-crystalline nanostructures due to the system-inherent capillary force in combination with external fields or forces are investigated in the frame of this dissertation by means of atomistic computer simulations. For the exploration (search, description, and prediction) of reaction pathways of nanostructure shape transformations, kinetic Monte Carlo (KMC) simulations are the method of choice. Since the employed KMC code is founded on a cellular automaton principle, the spatio-temporal development of lattice-based N-particle systems (N up to several million) can be followed for time spans of several orders of magnitude, while considering local phenomena due to atomic-scale effects like diffusion, nucleation, dissociation, or ballistic displacements. In this work, the main emphasis is put on nanostructures which have a cylindrical geometry, for example, nanowires (NWs), nanorods, nanotubes etc

  10. Validation of Varian TrueBeam electron phase–spaces for Monte Carlo simulation of MLC-shaped fields

    International Nuclear Information System (INIS)

    Lloyd, Samantha A. M.; Gagne, Isabelle M.; Zavgorodni, Sergei; Bazalova-Carter, Magdalena

    2016-01-01

    Purpose: This work evaluates Varian’s electron phase–space sources for Monte Carlo simulation of the TrueBeam for modulated electron radiation therapy (MERT) and combined, modulated photon and electron radiation therapy (MPERT) where fields are shaped by the photon multileaf collimator (MLC) and delivered at 70 cm SSD. Methods: Monte Carlo simulations performed with EGSnrc-based BEAMnrc/DOSXYZnrc and PENELOPE-based PRIMO are compared against diode measurements for 5 × 5, 10 × 10, and 20 × 20 cm 2 MLC-shaped fields delivered with 6, 12, and 20 MeV electrons at 70 cm SSD (jaws set to 40 × 40 cm 2 ). Depth dose curves and profiles are examined. In addition, EGSnrc-based simulations of relative output as a function of MLC-field size and jaw-position are compared against ion chamber measurements for MLC-shaped fields between 3 × 3 and 25 × 25 cm 2 and jaw positions that range from the MLC-field size to 40 × 40 cm 2 . Results: Percent depth dose curves generated by BEAMnrc/DOSXYZnrc and PRIMO agree with measurement within 2%, 2 mm except for PRIMO’s 12 MeV, 20 × 20 cm 2 field where 90% of dose points agree within 2%, 2 mm. Without the distance to agreement, differences between measurement and simulation are as large as 7.3%. Characterization of simulated dose parameters such as FWHM, penumbra width and depths of 90%, 80%, 50%, and 20% dose agree within 2 mm of measurement for all fields except for the FWHM of the 6 MeV, 20 × 20 cm 2 field which falls within 2 mm distance to agreement. Differences between simulation and measurement exist in the profile shoulders and penumbra tails, in particular for 10 × 10 and 20 × 20 cm 2 fields of 20 MeV electrons, where both sets of simulated data fall short of measurement by as much as 3.5%. BEAMnrc/DOSXYZnrc simulated outputs agree with measurement within 2.3% except for 6 MeV MLC-shaped fields. Discrepancies here are as great as 5.5%. Conclusions: TrueBeam electron phase–spaces available from Varian have been

  11. Validation of Varian TrueBeam electron phase–spaces for Monte Carlo simulation of MLC-shaped fields

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Samantha A. M. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8P 3P6 5C2 (Canada); Gagne, Isabelle M., E-mail: imgagne@bccancer.bc.ca; Zavgorodni, Sergei [Department of Medical Physics, BC Cancer Agency–Vancouver Island Centre, Victoria, British Columbia V8R 6V5, Canada and Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 3P6 5C2 (Canada); Bazalova-Carter, Magdalena [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 3P6 5C2 (Canada)

    2016-06-15

    Purpose: This work evaluates Varian’s electron phase–space sources for Monte Carlo simulation of the TrueBeam for modulated electron radiation therapy (MERT) and combined, modulated photon and electron radiation therapy (MPERT) where fields are shaped by the photon multileaf collimator (MLC) and delivered at 70 cm SSD. Methods: Monte Carlo simulations performed with EGSnrc-based BEAMnrc/DOSXYZnrc and PENELOPE-based PRIMO are compared against diode measurements for 5 × 5, 10 × 10, and 20 × 20 cm{sup 2} MLC-shaped fields delivered with 6, 12, and 20 MeV electrons at 70 cm SSD (jaws set to 40 × 40 cm{sup 2}). Depth dose curves and profiles are examined. In addition, EGSnrc-based simulations of relative output as a function of MLC-field size and jaw-position are compared against ion chamber measurements for MLC-shaped fields between 3 × 3 and 25 × 25 cm{sup 2} and jaw positions that range from the MLC-field size to 40 × 40 cm{sup 2}. Results: Percent depth dose curves generated by BEAMnrc/DOSXYZnrc and PRIMO agree with measurement within 2%, 2 mm except for PRIMO’s 12 MeV, 20 × 20 cm{sup 2} field where 90% of dose points agree within 2%, 2 mm. Without the distance to agreement, differences between measurement and simulation are as large as 7.3%. Characterization of simulated dose parameters such as FWHM, penumbra width and depths of 90%, 80%, 50%, and 20% dose agree within 2 mm of measurement for all fields except for the FWHM of the 6 MeV, 20 × 20 cm{sup 2} field which falls within 2 mm distance to agreement. Differences between simulation and measurement exist in the profile shoulders and penumbra tails, in particular for 10 × 10 and 20 × 20 cm{sup 2} fields of 20 MeV electrons, where both sets of simulated data fall short of measurement by as much as 3.5%. BEAMnrc/DOSXYZnrc simulated outputs agree with measurement within 2.3% except for 6 MeV MLC-shaped fields. Discrepancies here are as great as 5.5%. Conclusions: TrueBeam electron phase

  12. Impulse electron gun with plasma cathode for realization of large diameter tube-shaped beams

    International Nuclear Information System (INIS)

    Antipov, V.S.; Karpukhin, V.I.; Kornilov, E.A.

    1999-01-01

    There are presented the results of investigations of a plasma electron source based on the gas discharge in a coaxial system of electrodes with longitudinal magnetic field. The examination is fulfilled from the viewpoint of applying the source as a plasma cathode for hybrid plasma-waveguide slow-wave structures on the basis of a disk-loaded coaxial. The source is optimized in order to get a powerful (up to 100 kW) nonrelativistic electron beam with the annular cross-section of a large diameter in the regime of relatively long current pulses (up to 0.2 ms) under the gas pressure ∼ 5 centre dot 10 -4 mm Hg in the area of the discharge burning

  13. Wireless energy transfer: Dielectric lens antennas for beam shaping in wireless power-transfer applications

    Science.gov (United States)

    Gonçalves, Ricardo; Carvalho, Nuno B.; Pinho, Pedro

    2017-02-01

    In the current contest of wireless systems, the last frontier remains the cut of the power cord. In that sense, the interest over wireless energy transfer technologies in the past years has grown exponentially. However, there are still many challenges to be overcome in order to enable wireless energy transfer full potential. One of the focus in the development of such systems is the design of very-high-gain, highly efficient, antennas that can compensate for the propagation loss of radio signals over the air. In this paper, we explore the design and manufacturing process of dielectric lenses, fabricated using a professional-grade desktop 3D printer. Lens antennas are used in order to increase beam efficiency and therefore maximize the efficiency of a wireless power-transfer system operating at microwave frequencies in the Ku band. Measurements of two fabricated prototypes showcase a large directivity, as predicted with simulations. xml:lang="fr"

  14. Z-Slicer: A Scheme for Shaping the Electron Beam Profile in a Linac

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraj, J. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Crawford, D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Broemmelsiek, D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Thurman-Keup, R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Baffes, C. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wortley, W. [Univ. of Rochester, NY (United States)

    2014-01-01

    A train of short bunches ( 100 fs) are at a premium at accelerator facilities and their applications include terahertz (THz) generation, short bunch diagnostics, advanced accelerator R&D, etc. In this work we report on the design and simulation of an experiment involving a 20 MeV electron beam, that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through unaffected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, or transverse deflecting cavity. The tuning variable is only the RF-chirp. The detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream.

  15. Fast spatial beam shaping by acousto-optic diffraction for 3D non-linear microscopy.

    Science.gov (United States)

    Akemann, Walther; Léger, Jean-François; Ventalon, Cathie; Mathieu, Benjamin; Dieudonné, Stéphane; Bourdieu, Laurent

    2015-11-02

    Acousto-optic deflection (AOD) devices offer unprecedented fast control of the entire spatial structure of light beams, most notably their phase. AOD light modulation of ultra-short laser pulses, however, is not straightforward to implement because of intrinsic chromatic dispersion and non-stationarity of acousto-optic diffraction. While schemes exist to compensate chromatic dispersion, non-stationarity remains an obstacle. In this work we demonstrate an efficient AOD light modulator for stable phase modulation using time-locked generation of frequency-modulated acoustic waves at the full repetition rate of a high power laser pulse amplifier of 80 kHz. We establish the non-local relationship between the optical phase and the generating acoustic frequency function and verify the system for temporal stability, phase accuracy and generation of non-linear two-dimensional phase functions.

  16. Feasibility of sealed D-T neutron generator as neutron source for liver BNCT and its beam shaping assembly.

    Science.gov (United States)

    Liu, Zheng; Li, Gang; Liu, Linmao

    2014-04-01

    This paper involves the feasibility of boron neutron capture therapy (BNCT) for liver tumor with four sealed neutron generators as neutron source. Two generators are placed on each side of the liver. The high energy of these emitted neutrons should be reduced by designing a beam shaping assembly (BSA) to make them useable for BNCT. However, the neutron flux decreases as neutrons pass through different materials of BSA. Therefore, it is essential to find ways to increase the neutron flux. In this paper, the feasibility of using low enrichment uranium as a neutron multiplier is investigated to increase the number of neutrons emitted from D-T neutron generators. The neutron spectrum related to our system has a proper epithermal flux, and the fast and thermal neutron fluxes comply with the IAEA recommended values. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Reducing aberration effect of Fourier transform lens by modifying Fourier spectrum of diffractive optical element in beam shaping optical system.

    Science.gov (United States)

    Zhang, Fang; Zhu, Jing; Song, Qiang; Yue, Weirui; Liu, Jingdan; Wang, Jian; Situ, Guohai; Huang, Huijie

    2015-10-20

    In general, Fourier transform lenses are considered as ideal in the design algorithms of diffractive optical elements (DOEs). However, the inherent aberrations of a real Fourier transform lens disturb the far field pattern. The difference between the generated pattern and the expected design will impact the system performance. Therefore, a method for modifying the Fourier spectrum of DOEs without introducing other optical elements to reduce the aberration effect of the Fourier transform lens is proposed. By applying this method, beam shaping performance is improved markedly for the optical system with a real Fourier transform lens. The experiments carried out with a commercial Fourier transform lens give evidence for this method. The method is capable of reducing the system complexity as well as improving its performance.

  18. Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

    International Nuclear Information System (INIS)

    Wan, Y. C.; Tok, E. S.; Teoh, H. F.; Sow, C. H.

    2015-01-01

    We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl 4 solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au 3+ ions to form Au NPs when HAuCl 4 solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl 4 . The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs

  19. Welding feasibility study of U-shape lips at ITER Port-Plug with new laser beam sources

    Energy Technology Data Exchange (ETDEWEB)

    Behr, W., E-mail: w.behr@fz-juelich.de; Faidel, D.; Fischer, K.; Pap, M.; Offermanns, G.

    2013-10-15

    A “Cut and weld feasibility study of U shape lips” shown on June 2007 was initial of the following investigations. A new solution for Port Plug sealing at ITER was demanded and the experience in laser beam welding of the ZAT (Central Institute of Technology) in Jülich (Research Centre Jülich) offered an alternative solution. Up to now mechanically fixed sealing or sealing by TIG welding is used with typical benefits and problems, as heat input, shrinkage or limited room for tools. New disc-laser application for tight welding (leakage rate < 10{sup −9} mbar l/s) of the sealing lips is presented in the following. Both in the metallographic investigation and by means of leakage rate investigation the suitability of the selected procedure as seal alternative at the ITER Port Plug could be pointed out. The distance between two connections can be reduced to approx. 5 mm. The presented milling process for weld seam removal offers an option additionally to laser beam cutting. Final tests with a new disc-laser source offered additional benefits concerning seam quality, process stability and seam geometry. The distance between two connections will be reduced to less than 3 mm in next investigations. Construction unit near investigations and a demo part in original size underline finally the industrial suitability of the laser-welding-process for Port-Plug sealing at ITER.

  20. Controlling the Laser Guide Star power density distribution at Sodium layer by combining Pre-correction and Beam-shaping

    Science.gov (United States)

    Huang, Jian; Wei, Kai; Jin, Kai; Li, Min; Zhang, YuDong

    2018-06-01

    The Sodium laser guide star (LGS) plays a key role in modern astronomical Adaptive Optics Systems (AOSs). The spot size and photon return of the Sodium LGS depend strongly on the laser power density distribution at the Sodium layer and thus affect the performance of the AOS. The power density distribution is degraded by turbulence in the uplink path, launch system aberrations, the beam quality of the laser, and so forth. Even without any aberrations, the TE00 Gaussian type is still not the optimal power density distribution to obtain the best balance between the measurement error and temporal error. To optimize and control the LGS power density distribution at the Sodium layer to an expected distribution type, a method that combines pre-correction and beam-shaping is proposed. A typical result shows that under strong turbulence (Fried parameter (r0) of 5 cm) and for a quasi-continuous wave Sodium laser (power (P) of 15 W), in the best case, our method can effectively optimize the distribution from the Gaussian type to the "top-hat" type and enhance the photon return flux of the Sodium LGS; at the same time, the total error of the AOS is decreased by 36% with our technique for a high power laser and poor seeing.

  1. Spontaneous decoration of Au nanoparticles on micro-patterned reduced graphene oxide shaped by focused laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Y. C.; Tok, E. S. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Teoh, H. F. [Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore); Sow, C. H. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456 (Singapore)

    2015-02-07

    We report a facile, two-step method for the micro-landscaping of Au nanoparticles(NPs) on reduced graphene oxide (rGO) film en route to micro-patterned Au(NPs)-rGO hybrid functional materials. This method employs a focused laser beam to first locally convert GO to rGO before immersing the micro-patterned GO-rGO film into HAuCl{sub 4} solution. The rGO micro-pattern, shaped by the focused laser beam, serves as nucleation sites for the reduction of Au ions. The reduction mechanism that governs the decoration of Au NPs on rGO films is akin to electroless deposition process. In this instance, surface charges that are formed during laser reduction of GO to rGO provide active nucleation sites for Au{sup 3+} ions to form Au NPs when HAuCl{sub 4} solution is introduced. The number density, the size, and size distribution of the Au NPs can thus be directly tuned and preferentially anchored onto the rGO micro-pattern by varying the incident laser power, the scanning speed of the laser, or the concentration of HAuCl{sub 4}. The resulting hybrid materials can be used as a substrate for Surface Enhanced Raman Spectroscopy (SERS). Using Rhodamine 6G as the test subject, we found an improvement of SERS enhancement over bare rGO of up to four times, depending on the size of the Au NPs.

  2. Compact D-D Neutron Source-Driven Subcritical Multiplier and Beam-Shaping Assembly for Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    Ganda, Francesco; Vujic, Jasmina; Greenspan, Ehud; Leung, Ka-Ngo

    2010-01-01

    This work assesses the feasibility of using a small, safe, and inexpensive keff 0.98 subcritical fission assembly [subcritical neutron multiplier (SCM)] to amplify the treatment neutron beam intensity attainable from a compact deuterium-deuterium (D-D) fusion neutron source delivering [approximately]1012 n/s. The objective is to reduce the treatment time for deep-seated brain tumors to [approximately]1 h. The paper describes the optimal SCM design and two optimal beam-shaping assemblies (BSAs) - one designed to maximize the dose rate and the other designed to maximize the total dose that can be delivered to a deep-seated tumor. The neutron beam intensity amplification achieved with the optimized SCM and BSA results in an increase in the treatment dose rate by a factor of 18: from 0.56 Gy/h without the SCM to 10.1 Gy/h. The entire SCM is encased in an aluminum structure. The total amount of 20% enriched uranium required for the SCM is 8.5 kg, and the cost (not including fabrication) is estimated to be less than $60,000. The SCM power level is estimated at 400 W when driven by a 1012 n/s D-D neutron source. This translates into consumption of only [approximately]0.6% of the initially loaded 235U atoms during 50 years of continuous operation and implies that the SCM could operate continuously for the entire lifetime of the facility without refueling. Cooling the SCM does not pose a challenge; it may be accomplished by natural circulation as the maximum heat flux is only 0.034 W/cm2.

  3. Observation of High Transformer Ratio of Shaped Bunch Generated by an Emittance-Exchange Beam Line.

    Science.gov (United States)

    Gao, Q; Ha, G; Jing, C; Antipov, S P; Power, J G; Conde, M; Gai, W; Chen, H; Shi, J; Wisniewski, E E; Doran, D S; Liu, W; Whiteford, C E; Zholents, A; Piot, P; Baturin, S S

    2018-03-16

    Collinear wakefield acceleration has been long established as a method capable of generating ultrahigh acceleration gradients. Because of the success on this front, recently, more efforts have shifted towards developing methods to raise the transformer ratio (TR). This figure of merit is defined as the ratio of the peak acceleration field behind the drive bunch to the peak deceleration field inside the drive bunch. TR is always less than 2 for temporally symmetric drive bunch distributions and therefore recent efforts have focused on generating asymmetric distributions to overcome this limitation. In this Letter, we report on using the emittance-exchange method to generate a shaped drive bunch to experimentally demonstrate a TR≈5 in a dielectric wakefield accelerator.

  4. Beam shaping assembly of a D-T neutron source for BNCT and its dosimetry simulation in deeply-seated tumor

    Science.gov (United States)

    Faghihi, F.; Khalili, S.

    2013-08-01

    This article involves two aims for BNCT. First case includes a beam shaping assembly estimation for a D-T neutron source to find epi-thermal neutrons which are the goal in the BNCT. Second issue is the percent depth dose calculation in the adult Snyder head phantom. Monte-Carlo simulations and verification of a suggested beam shaping assembly (including internal neutron multiplier, moderator, filter, external neutron multiplier, collimator, and reflector dimensions) for thermalizing a D-T neutron source as well as increasing neutron flux are carried out and our results are given herein. Finally, we have simulated its corresponding doses for treatment planning of a deeply-seated tumor.

  5. Influence of cell shape on mechanical properties of Ti-6Al-4V meshes fabricated by electron beam melting method.

    Science.gov (United States)

    Li, S J; Xu, Q S; Wang, Z; Hou, W T; Hao, Y L; Yang, R; Murr, L E

    2014-10-01

    Ti-6Al-4V reticulated meshes with different elements (cubic, G7 and rhombic dodecahedron) in Materialise software were fabricated by additive manufacturing using the electron beam melting (EBM) method, and the effects of cell shape on the mechanical properties of these samples were studied. The results showed that these cellular structures with porosities of 88-58% had compressive strength and elastic modulus in the range 10-300MPa and 0.5-15GPa, respectively. The compressive strength and deformation behavior of these meshes were determined by the coupling of the buckling and bending deformation of struts. Meshes that were dominated by buckling deformation showed relatively high collapse strength and were prone to exhibit brittle characteristics in their stress-strain curves. For meshes dominated by bending deformation, the elastic deformation corresponded well to the Gibson-Ashby model. By enhancing the effect of bending deformation, the stress-strain curve characteristics can change from brittle to ductile (the smooth plateau area). Therefore, Ti-6Al-4V cellular solids with high strength, low modulus and desirable deformation behavior could be fabricated through the cell shape design using the EBM technique. Copyright © 2014 Acta Materialia Inc. All rights reserved.

  6. Electronic regulation of the SPS extraction quadrupole current pulse shape for improved stability of the extracted beam

    CERN Document Server

    Carlier, E; Vossenberg, Eugène B; CERN. Geneva. SPS and LEP Division

    1996-01-01

    In order to minimise the event pile-up and therefore optimise the detection efficiency, Chorus and Nomad experiments ask for a long and rectangular spill profile. At present the fast-slow extractio n is generated by driving the beam into a quadrupolar-octopolar resonance by exciting a quadrupole magnet with a semi-trapezoidal current [1]. The trapezoidal pulse shape is obtained by dischargin g a capacitor into the magnet coils. After a few milliseconds of undamped discharge a fixed resistor is switched into the circuit. The attenuation is then higher and the sine wave continues with a lower gradient. The two gradients can be adjusted by varying the initial capacitor voltage and the time at which the resistor is switched into the circuit. A further degree of freedom in determini ng the spill shape has been added by allowing the possibility of changing the second slope value independently of the initial conditions. This task is achieved by means of a variable current sour ce added in parallel to the fixed resis...

  7. Pulse Shape Characterization of Silicon Diodes for HGCal with data from Beam Test at CERN

    CERN Document Server

    De Silva, Malinda

    2016-01-01

    The High Luminosity phase of the LHC (starting operation in 2025) will provide unprecedented instantaneous and integrated luminosity, with 25 ns bunch crossing intervals and up to 140 pileup events. A challenge is to provide excellent physics performance in such a harsh environment to fully exploit the HL-LHC potentialities and explore new physics frontiers. In this context, the High Granularity Calorimeter is the detector designed to provide electromagnetic and hadronic energy coverage and reconstruction in the forward direction of the upgraded CMS. In April 2016 and June 2016, a set of 36 diodes were tested in order to understand various characteristics of its performance, in order to use them in the upgraded HG Calorimeter. Here, the silicon diodes were mounted onto a test bench at CERN’s beam test area and exposed to electron showers. Data received from these diodes were acquired and analysed separately. The objective of this report is to show the variation of Time Rise, Time Over Threshold with various...

  8. Spectral structure of a polycapillary lens shaped X-ray beam

    Science.gov (United States)

    Gogolev, A. S.; Filatov, N. A.; Uglov, S. R.; Hampai, D.; Dabagov, S. B.

    2018-04-01

    Polycapillary X-ray optics is widely used in X-ray analysis techniques to create a small secondary source, for instance, or to deliver X-rays to the point of interest with minimum intensity losses [1]. The main characteristics of the analytical devices on its base are the size and divergence of the focused or translated beam. In this work, we used the photon-counting pixel detector ModuPIX to study the parameters for polycapillary focused X-ray tube radiation as well as the energy and spatial dependences of radiation at the focus. We have characterized the high-speed spectral camera ModuPIX, which is a single Timepix device with a fast parallel readout allowing up to 850 frames per second with 256 × 256 pixels and a 55 μm pitch defined by the frame frequency. By means of the silicon monochromator the energy response function is measured in clustering mode by the energy scan over total X-ray tube spectrum.

  9. Generic method for automatic bladder segmentation on cone beam CT using a patient-specific bladder shape model

    International Nuclear Information System (INIS)

    Schoot, A. J. A. J. van de; Schooneveldt, G.; Wognum, S.; Stalpers, L. J. A.; Rasch, C. R. N.; Bel, A.; Hoogeman, M. S.; Chai, X.

    2014-01-01

    Purpose: The aim of this study is to develop and validate a generic method for automatic bladder segmentation on cone beam computed tomography (CBCT), independent of gender and treatment position (prone or supine), using only pretreatment imaging data. Methods: Data of 20 patients, treated for tumors in the pelvic region with the entire bladder visible on CT and CBCT, were divided into four equally sized groups based on gender and treatment position. The full and empty bladder contour, that can be acquired with pretreatment CT imaging, were used to generate a patient-specific bladder shape model. This model was used to guide the segmentation process on CBCT. To obtain the bladder segmentation, the reference bladder contour was deformed iteratively by maximizing the cross-correlation between directional grey value gradients over the reference and CBCT bladder edge. To overcome incorrect segmentations caused by CBCT image artifacts, automatic adaptations were implemented. Moreover, locally incorrect segmentations could be adapted manually. After each adapted segmentation, the bladder shape model was expanded and new shape patterns were calculated for following segmentations. All available CBCTs were used to validate the segmentation algorithm. The bladder segmentations were validated by comparison with the manual delineations and the segmentation performance was quantified using the Dice similarity coefficient (DSC), surface distance error (SDE) and SD of contour-to-contour distances. Also, bladder volumes obtained by manual delineations and segmentations were compared using a Bland-Altman error analysis. Results: The mean DSC, mean SDE, and mean SD of contour-to-contour distances between segmentations and manual delineations were 0.87, 0.27 cm and 0.22 cm (female, prone), 0.85, 0.28 cm and 0.22 cm (female, supine), 0.89, 0.21 cm and 0.17 cm (male, supine) and 0.88, 0.23 cm and 0.17 cm (male, prone), respectively. Manual local adaptations improved the segmentation

  10. Cold-Fluid Equilibrium of a Large-Aspect-Ratio Ellipse-Shaped Charged-Particle Beam in a Non-Axisymmetric Periodic Permanent Magnet Focusing Field

    CERN Document Server

    Zhou, Jing; Chen Chi Ping

    2005-01-01

    A new class of equilibrium is discovered for a large-aspect-ratio ellipse-shaped charged-particle beam in a non-axisymmetric periodic permanent magnet focusing field. A paraxial cold-fluid model is employed to derive the equilibrium flow properties and generalized envelope equations with negligibly small emittance. A periodic beam equilibrium solution is obtained numerically from the generalized envelope equations. It is shown that the beam edges are well confined in both transverse directions, and that the equilibrium beam exhibits a small-angle periodic wobble as it propagates. A two-dimensional particle-in-cell (PIC) code, PFB2D, is used to verify the theoretical predictions in the paraxial limit, and to establish validity under non-paraxial situations and the influence of the conductor walls of the beam tunnel.

  11. 3D printed plano-freeform optics for non-coherent discontinuous beam shaping

    Science.gov (United States)

    Assefa, Bisrat G.; Saastamoinen, Toni; Biskop, Joris; Kuittinen, Markku; Turunen, Jari; Saarinen, Jyrki

    2018-06-01

    The design, fabrication, and characterization of freeform optics for LED-based complex target irradiance distribution are challenging. Here, we investigate a 3D printing technology called Printoptical® technology in order to relax or push forward both the fabrication limits and LED-based applications of thick freeform lenses with small slope features. The freeform designs are carried out with an assumption of small-sized LED source using an existing point-source-based Tailoring method, which is available in the semi-commercial software. The numerical methods of the designs are characterized by ray-tracing software. The irradiance patterns of the 3D printed freeform lenses are promising considering the average shape conformity deviation of around ± 40 µm and center area surface roughness around ± 12 nm, which is to our knowledge by far the best result reported for 3D printed freeform lenses with a thickness greater than 1 mm. Applications of freeform lenses with discontinuous target irradiance distribution patterns are expected in eco-friendly energy efficient lighting such as in zebra-cross lighting.

  12. 3D printed plano-freeform optics for non-coherent discontinuous beam shaping

    Science.gov (United States)

    Assefa, Bisrat G.; Saastamoinen, Toni; Biskop, Joris; Kuittinen, Markku; Turunen, Jari; Saarinen, Jyrki

    2018-03-01

    The design, fabrication, and characterization of freeform optics for LED-based complex target irradiance distribution are challenging. Here, we investigate a 3D printing technology called Printoptical® technology in order to relax or push forward both the fabrication limits and LED-based applications of thick freeform lenses with small slope features. The freeform designs are carried out with an assumption of small-sized LED source using an existing point-source-based Tailoring method, which is available in the semi-commercial software. The numerical methods of the designs are characterized by ray-tracing software. The irradiance patterns of the 3D printed freeform lenses are promising considering the average shape conformity deviation of around ± 40 µm and center area surface roughness around ± 12 nm, which is to our knowledge by far the best result reported for 3D printed freeform lenses with a thickness greater than 1 mm. Applications of freeform lenses with discontinuous target irradiance distribution patterns are expected in eco-friendly energy efficient lighting such as in zebra-cross lighting.

  13. Analysis of shape and spatial interaction of synaptic vesicles using data from focused ion beam scanning electron microscopy (FIB-SEM)

    DEFF Research Database (Denmark)

    Khanmohammadi, Mahdieh; Waagepetersen, Rasmus Plenge; Sporring, Jon

    2015-01-01

    deviations from spherical shape and systematic trends in their orientation. We studied three-dimensional representations of synapses obtained by manual annotation of focused ion beam scanning electron microscopy (FIB-SEM) images of male mouse brain. The configurations of synaptic vesicles were regarded...... in excitatory synapses appeared to be of oblate ellipsoid shape and in inhibitory synapses appeared to be of cigar ellipsoid shape, and followed a systematic pattern regarding their orientation towards the active zone. Moreover, there was strong evidence of spatial alignment in the orientations of pairs...

  14. GO Shaping of Omnidirectional Dual-Reflector Antennas with Arbitrary Main-Beam Direction in Elevation Plane by Connecting Conic Sections

    Directory of Open Access Journals (Sweden)

    Rafael A. Penchel

    2018-01-01

    Full Text Available This work discusses an alternative geometrical optics (GO technique to synthesize omnidirectional dual-reflector antennas with uniform aperture phase distribution together with an arbitrary main-beam direction for the antenna radiation pattern. Sub- and main reflectors are bodies of revolution generated by shaped curves defined by local conic sections consecutively concatenated. The shaping formulation is derived for configurations like ADC (axis-displaced Cassegrain and ADE (axis-displaced ellipse omnidirectional antennas. As case studies, two configurations fed by a TEM coaxial horn are designed and analyzed by a hybrid technique based on mode matching and method of moments in order to validate the GO shaping procedure.

  15. End-pumped Nd:YVO4 laser with reduced thermal lensing via the use of a ring-shaped pump beam.

    Science.gov (United States)

    Lin, Di; Andrew Clarkson, W

    2017-08-01

    A simple approach for alleviating thermal lensing in end-pumped solid-state lasers using a pump beam with a ring-shaped intensity distribution to decrease the radial temperature gradient is described. This scheme has been implemented in a diode-end-pumped Nd:YVO 4 laser yielding 14 W of TEM 00 output at 1.064 μm with a corresponding slope efficiency of 53% and a beam propagation factor (M 2 ) of 1.08 limited by available pump power. By comparison, the same laser design with a conventional quasi-top-hat pump beam profile of approximately equal radial extent yielded only 9 W of output before the power rolled over due to thermal lensing. Further investigation with the aid of a probe beam revealed that the thermal lens power was ∼30% smaller for the ring-shaped pump beam compared to the quasi-top-hat beam. The implications for further power scaling in end-pumped laser configurations are considered.

  16. Improvement of uniformity of the negative ion beams by tent-shaped magnetic field in the JT-60 negative ion source

    International Nuclear Information System (INIS)

    Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; Nemoto, Shuji; Ohzeki, Masahiro; Seki, Norikazu; Sasaki, Shunichi; Shimizu, Tatsuo; Terunuma, Yuto; Grisham, Larry R.

    2014-01-01

    Non-uniformity of the negative ion beams in the JT-60 negative ion source with the world-largest ion extraction area was improved by modifying the magnetic filter in the source from the plasma grid (PG) filter to a tent-shaped filter. The magnetic design via electron trajectory calculation showed that the tent-shaped filter was expected to suppress the localization of the primary electrons emitted from the filaments and created uniform plasma with positive ions and atoms of the parent particles for the negative ions. By modifying the magnetic filter to the tent-shaped filter, the uniformity defined as the deviation from the averaged beam intensity was reduced from 14% of the PG filter to ∼10% without a reduction of the negative ion production

  17. On beam shaping of the field radiated by a line source coupled to finite or infinite photonic crystals.

    Science.gov (United States)

    Ceccuzzi, Silvio; Jandieri, Vakhtang; Baccarelli, Paolo; Ponti, Cristina; Schettini, Giuseppe

    2016-04-01

    Comparison of the beam-shaping effect of a field radiated by a line source, when an ideal infinite structure constituted by two photonic crystals and an actual finite one are considered, has been carried out by means of two different methods. The lattice sums technique combined with the generalized reflection matrix method is used to rigorously investigate the radiation from the infinite photonic crystals, whereas radiation from crystals composed of a finite number of rods along the layers is analyzed using the cylindrical-wave approach. A directive radiation is observed with the line source embedded in the structure. With an increased separation distance between the crystals, a significant edge diffraction appears that provides the main radiation mechanism in the finite layout. Suitable absorbers are implemented to reduce the above-mentioned diffraction and the reflections at the boundaries, thus obtaining good agreement between radiation patterns of a localized line source coupled to finite and infinite photonic crystals, when the number of periods of the finite structure is properly chosen.

  18. Adjustable mounting device for high-volume production of beam-shaping systems for high-power diode lasers

    Science.gov (United States)

    Haag, Sebastian; Bernhardt, Henning; Rübenach, Olaf; Haverkamp, Tobias; Müller, Tobias; Zontar, Daniel; Brecher, Christian

    2015-02-01

    In many applications for high-power diode lasers, the production of beam-shaping and homogenizing optical systems experience rising volumes and dynamical market demands. The automation of assembly processes on flexible and reconfigurable machines can contribute to a more responsive and scalable production. The paper presents a flexible mounting device designed for the challenging assembly of side-tab based optical systems. It provides design elements for precisely referencing and fixating two optical elements in a well-defined geometric relation. Side tabs are presented to the machine allowing the application of glue and a rotating mechanism allows the attachment to the optical elements. The device can be adjusted to fit different form factors and it can be used in high-volume assembly machines. The paper shows the utilization of the device for a collimation module consisting of a fast-axis and a slow-axis collimation lens. Results regarding the repeatability and process capability of bonding side tab assemblies as well as estimates from 3D simulation for overall performance indicators achieved such as cycle time and throughput will be discussed.

  19. MO-FG-CAMPUS-IeP2-01: Characterization of Beam Shaping Filters and Photon Spectra From HVL Profiles in CT

    Energy Technology Data Exchange (ETDEWEB)

    Bujila, R [Karolinska University Hospital, Stockholm (Sweden); Royal Institute of Technology, Stockholm (Sweden); Kull, L [Sunderby Hospital, Lulea (Sweden); Nowik, P; Poludniowski, G [Karolinska University Hospital, Stockholm (Sweden); Andersson, J [Umea University, Umea (Sweden)

    2016-06-15

    Purpose: Advanced dosimetry in CT (e.g. the Monte Carlo method) requires an accurate characterization of the shaped filter and radiation quality used during a scan. The purpose of this work was to develop a method where half value layer (HVL) profiles along shaped filters could be made. From the HVL profiles the beam shaping properties and effective photon spectrum for a particular scan can be inferred. Methods: A measurement rig was developed to allow determinations of the HVL under a scatter-free narrow-beam geometry and constant focal spot to ionization chamber distance for different fan angles. For each fan angle the HVL is obtained by fitting the transmission of radiation through different thicknesses of an Al absorber (type 1100) using an appropriate model. The effective Al thickness of shaped filters and effective photon spectra are estimated using a model of photon emission from a Tungsten anode. This method is used to obtain the effective photon spectra and effective Al thickness of shaped filters for a CT scanner recently introduced to the market. Results: This study resulted in a set of effective photon spectra (central ray) for each kVp along with effective Al thicknesses of the different shaped filters. The effective photon spectra and effective Al thicknesses of shaped filters were used to obtain numerically approximated HVL profiles and compared to measured HVL profiles (mean absolute percentage error = 0.02). The central axis HVL found in the vendor’s technical documentation were compared to approximated HVL values (mean absolute percentage error = 0.03). Conclusion: This work has resulted in a unique method of measuring HVL profiles along shaped filters in CT. Further the effective photon spectra and the effective Al thicknesses of shaped filters that were obtained can be incorporated into Monte Carlo simulations.

  20. A practical method to calculate head scatter factors in wedged rectangular and irregular MLC shaped beams for external and internal wedges

    International Nuclear Information System (INIS)

    Georg, Dietmar; Olofsson, Joergen; Kuenzler, Thomas; Aiginger, Hannes; Karlsson, Mikael

    2004-01-01

    Factor based methods for absorbed dose or monitor unit calculations are often based on separate data sets for open and wedged beams. The determination of basic beam parameters can be rather time consuming, unless equivalent square methods are applied. When considering irregular wedged beams shaped with a multileaf collimator, parametrization methods for dosimetric quantities, e.g. output ratios or wedge factors as a function of field size and shape, become even more important. A practical method is presented to derive wedged output ratios in air (S c,w ) for any rectangular field and for any irregular MLC shaped beam. This method was based on open field output ratios in air (S c ) for a field with the same collimator setting, and a relation f w between S c,w and S c . The relation f w can be determined from measured output ratios in air for a few open and wedged fields including the maximum wedged field size. The function f w and its parametrization were dependent on wedge angle and treatment head design, i.e. they were different for internal and external wedges. The proposed method was tested for rectangular wedged fields on three accelerators with internal wedges (GE, Elekta, BBC) and two accelerators with external wedges (Varian). For symmetric regular beams the average deviation between calculated and measured S c,w /S c ratios was 0.3% for external wedges and about 0.6% for internal wedges. Maximum deviations of 1.8% were obtained for elongated rectangular fields on the GE and ELEKTA linacs with an internal wedge. The same accuracy was achieved for irregular MLC shaped wedged beams on the accelerators with MLC and internal wedges (GE and Elekta), with an average deviation <1% for the fields tested. The proposed method to determine output ratios in air for wedged beams from output ratios of open beams, combined with equivalent square approaches, can be easily integrated in empirical or semi-empirical methods for monitor unit calculations

  1. Obtaining Empirical Validation of Shape-Coexistence in the Mass 70 Region: Coulomb Excitation of a Radioactive Beam of $^{70}$Se

    CERN Multimedia

    Andreoiu, C; Paul, E S; Czosnyka, T; Hammond, N

    2002-01-01

    We propose to study the Coulomb excitation of a radioactive beam of $^{70}$Se at 2.2 MeV/u obtained from the REX-ISOLDE facility in order to determine the sign of the quadrupole moment and, hence, the sign of the quadrupole deformation. Calculations suggest a 33~\\% sensitivity in Coulomb excitation yield for a nickel target depending on whether the nuclear shape is oblate or prolate. Such a determination would provide compelling evidence for the presence of oblate shapes in the vicinity of N=Z=34.

  2. Finite element analysis of smart reinforced concrete beam with super elastic shape memory alloy subjected to static loading for seismic mitigation

    Science.gov (United States)

    Hamid, Nubailah Abd; Ismail, Muhammad Hussain; Ibrahim, Azmi; Adnan, Azlan

    2018-05-01

    Reinforced concrete beam has been among major applications in construction nowadays. However, the application of nickel titanium alloy as a replacement for steel rebar in reinforced concrete beam is a new approach nowadays despite of their ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this paper, the response of simply supported reinforced concrete (RC) beams with smart rebars, control beam subjected to static load has been numerically studied, and highlighted, using finite element method (FEM) where the material employed in this study is the superelastic shape memory alloys (SESMA). The SESMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. The size of the analysed beam is 125 mm × 270 mm × 2800 mm with 2 numbers of 12 mm diameter bars as main reinforcement for compression and 12 numbers of 12 as tension or hanger bars while 6 mm diameter at 100 mm c/c used as shear reinforcement bars respectively. The concrete was modelled using solid 65 element (in ANSYS) and rebars were modelled using beam 188 elements (in ANSYS). The result for reinforced concrete with nickel titanium alloy rebar is compared with the result obtained for reinforced concrete beam with steel rebar in term of flexural behavior, load displacement relationship, crack behaviour and failure modes for various loading conditions starting from 10kN to 100kN using 3D FE modelling in ANSYS v 15. The response and result obtained from the 3D finite element analysis used in this study is load-displacement curves, residual displacements, Von-Misses, strain and stiffness are suitable for the corresponding result showed a satisfactory performance in the structural analysis. Resultant displacement, Von-Mises stress and maximum strain were influenced by the factors of the material properties, load increments and the mesh size. Nickel titanium alloy was superior to the

  3. Development of Adaptive Feedback Control System of Both Spatial and Temporal Beam Shaping for UV-Laser Light Source for RF Gun

    CERN Document Server

    Tomizawa, H; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Yanagida, K

    2004-01-01

    The ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. We have been developing highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. The gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. The electron beam was accelerated up to 4.1 MeV at the maximum electric field on the cathode surface of 175 MV/m. For emittance compensation, two solenoid coils were used. As the first test run, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2 π·mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We applied the both adaptive optics to automatically shape the bot...

  4. The I-Raum: A new shaped hohlraum for improved inner beam propagation in indirectly-driven ICF implosions on the National Ignition Facility

    Science.gov (United States)

    Robey, H. F.; Berzak Hopkins, L.; Milovich, J. L.; Meezan, N. B.

    2018-01-01

    Recent work in indirectly-driven inertial confinement fusion implosions on the National Ignition Facility has indicated that late-time propagation of the inner cones of laser beams (23° and 30°) is impeded by the growth of a "bubble" of hohlraum wall material (Au or depleted uranium), which is initiated by and is located at the location where the higher-intensity outer beams (44° and 50°) hit the hohlraum wall. The absorption of the inner cone beams by this "bubble" reduces the laser energy reaching the hohlraum equator at late time driving an oblate or pancaked implosion, which limits implosion performance. In this article, we present the design of a new shaped hohlraum designed specifically to reduce the impact of this bubble by adding a recessed pocket at the location where the outer cones hit the hohlraum wall. This recessed pocket displaces the bubble radially outward, reducing the inward penetration of the bubble at all times throughout the implosion and increasing the time for inner beam propagation by approximately 1 ns. This increased laser propagation time allows one to drive a larger capsule, which absorbs more energy and is predicted to improve implosion performance. The new design is based on a recent National Ignition Facility shot, N170601, which produced a record neutron yield. The expansion rate and absorption of laser energy by the bubble is quantified for both cylindrical and shaped hohlraums, and the predicted performance is compared.

  5. Prevalence of C-shaped canals in mandibular second and third molars in a central India population: A cone beam computed tomography analysis.

    Science.gov (United States)

    Wadhwani, Shefali; Singh, Mahesh Pratap; Agarwal, Manish; Somasundaram, Pavithra; Rawtiya, Manjusha; Wadhwani, P K

    2017-01-01

    To evaluate the prevalence of C-shaped root canals in mandibular molars using cone beam computed tomography (CBCT) in a subpopulation of Central India. CBCT scans of patients from diagnostic imaging center were selected in accordance with the criteria given by Fan et al . (2004) for C-shaped canals. A total of 238 CBCT scans fulfilled the inclusion criteria and thereby divided into two groups: Group 1: Images showing C-shaped canal configuration in mandibular second molars. Group 2: Images showing C-shaped canal configuration in mandibular third molars. The frequency and distribution of canals and their configuration along with the position of lingual/buccal grooves in the images were evaluated, and the data was analyzed. CBCT evaluation showed that 9.7% of second molars and 8% of third molars had C-shaped canals. A prominent buccal groove was seen in these teeth. The data showed a significant difference ( P = 0.038) for the presence of such anatomy on the right side for mandibular third molars. The study showed a significant prevalence of C-shaped canal configuration in the subpopulation studied.

  6. Derivation, evidence and physical validity of a weighted beam-zone method for dose determination in blocked photon fields of arbitrary shape

    International Nuclear Information System (INIS)

    Glaeser, L.; Quast, U.

    1981-01-01

    A simple, practical procedure for dose determination at any point of an arbitrarily shaped field has been derived: Square-field photon beams are sectioned into a set of pyramid-shell-like parts (beam zones), nested into each other around the smallest realizable square field, of different sizes but with equal dose contributions (thus weighted) with respect to a central dose reference point. The dose at any reference point in an irregular field can be determined simply by counting the number of non-shielded dose-contributing zones (or zone fractions), leading to the associated order of square-field size (with the same number of zones), the equivalent field with known dose. For experimental evidence of the validity of the weighted beam-zone method, measurements were carried out with different high-energy photon beams with one or more beam zones shielded by absorbing blocks. Measurements were made at points in unshielded and shielded parts of the field, on and off the beam axis and at different depths in a phantom. Calculations and measurements were compared. While relative depth doses were shown to be equal to within +-2% over a range of 5 cm ahead of and behind the dose reference point, the absolute dose deviations were within +-4%. The sources of error were analysed. They were mainly determined by scattered radiation from the beam limiting device and the partial shielding deriving from the shielding blocks. The same errors also occur in most of the known methods of dose calculation in irregular fields. (author)

  7. Simple beam profile monitor

    Energy Technology Data Exchange (ETDEWEB)

    Gelbart, W.; Johnson, R. R.; Abeysekera, B. [ASD Inc. Garden Bay, BC (Canada); Best Theratronics Ltd Ottawa Ontario (Canada); PharmaSpect Ltd., Burnaby BC (Canada)

    2012-12-19

    An inexpensive beam profile monitor is based on the well proven rotating wire method. The monitor can display beam position and shape in real time for particle beams of most energies and beam currents up to 200{mu}A. Beam shape, position cross-section and other parameters are displayed on a computer screen.

  8. Latest developments on fibered MOPA in mJ range with hollow-core fiber beam delivery and fiber beam shaping used as seeder for large scale laser facilities (Conference Presentation)

    Science.gov (United States)

    Gleyze, Jean-François; Scol, Florent; Perrin, Arnaud; Gouriou, Pierre; Valentin, Constance; Bouwmans, Géraud; Hugonnot, Emmanuel

    2017-05-01

    The Laser Megajoule (LMJ) is a French large scale laser facility dedicated to inertial fusion and plasma physics research. LMJ front-ends are based on fiber laser technology at nanojoule range [1]. Scaling the energy of those fiber seeders to the millijoule range is a way to upgrade LMJ's front ends architecture and could also be used as seeder for lasers for ELI project for example. However, required performances are so restrictive (optical-signal-to-noise ratio higher than 50 dB, temporally-shaped nanosecond pulses and spatial single-mode top-hat beam output) that such fiber systems are very tricky to build. High-energy fiber amplifiers In 2015, we have demonstrated, an all-fiber MOPA prototype able to produce a millijoule seeder, but unfortunately not 100% conform for all LMJ's performances. A major difficulty was to manage the frequency modulation used to avoid stimulated Brillouin scattering, to amplitude modulation (FM-AM) conversion, this limits the energy at 170µJ. For upgrading the energy to the millijoule range, it's necessary to use an amplifier with a larger core fiber. However, this fiber must still be flexible; polarization maintaining and exhibit a strictly single-mode behaviour. We are thus developing a new amplifier architecture based on an Yb-doped tapered fiber: its core diameter is from a narrow input to a wide output (MFD 8 to 26 µm). A S² measurement on a 2,5m long tapered fiber rolled-up on 22 cm diameter confirmed that this original geometry allows obtaining strictly single-mode behaviour. In a 1 kHz repetition rate regime, we already obtain 750 µJ pulses, and we are on the way to mJ, respecting LMJ performances. Beam delivery In LMJ architecture the distance between the nanojoule fiber seeder and the amplifier stages is about 16 m. Beam delivery is achieved with a standard PM fiber, such a solution is no longer achievable with hundreds of kilowatt peak powers. An efficient way to minimize nonlinear effects is to use hollow-core (HC

  9. Optimization of the beam shaping assembly in the D-D neutron generators-based BNCT using the response matrix method.

    Science.gov (United States)

    Kasesaz, Y; Khalafi, H; Rahmani, F

    2013-12-01

    Optimization of the Beam Shaping Assembly (BSA) has been performed using the MCNP4C Monte Carlo code to shape the 2.45 MeV neutrons that are produced in the D-D neutron generator. Optimal design of the BSA has been chosen by considering in-air figures of merit (FOM) which consists of 70 cm Fluental as a moderator, 30 cm Pb as a reflector, 2mm (6)Li as a thermal neutron filter and 2mm Pb as a gamma filter. The neutron beam can be evaluated by in-phantom parameters, from which therapeutic gain can be derived. Direct evaluation of both set of FOMs (in-air and in-phantom) is very time consuming. In this paper a Response Matrix (RM) method has been suggested to reduce the computing time. This method is based on considering the neutron spectrum at the beam exit and calculating contribution of various dose components in phantom to calculate the Response Matrix. Results show good agreement between direct calculation and the RM method. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Part I: $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with astatine beams; Part II: Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

    CERN Document Server

    Andreyev, Andrei

    2013-01-01

    Part I: $\\beta$-delayed fission, laser spectroscopy and shape-coexistence studies with astatine beams; Part II: Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

  11. Quasibound levels and shape resonances of 39K2(B 1Pi/sub u/) crossed laser-molecular beam studies and analytical interpretation

    International Nuclear Information System (INIS)

    Heinze, J.; Kowalczyk, P.; Engelke, F.

    1988-01-01

    Quasibound levels and shape resonances in the (B 1 Pi/sub u/ -X 1 Σ + /sub g/) band system of 39 K 2 have been recorded by crossed laser-molecular beam techniques. Using optical--optical double resonance, individual rovibrational levels (v'' = 15--18, J'' = 3--25) of the K 2 state are prepared by Franck--Condon pumping (FCP) in a supersonic nozzle beam. Excitation into quasibound levels below and above the (B 1 Pi/sub u/) state barrier is detected as molecular and atomic (K4 2 P 3 /sub // 2 →4 2 S 1 /sub // 2 only) fluorescence. The resonance transition frequencies and shapes are measured and the results are used (a) to determine the scattering resonance energies, widths, and lifetimes; (b) to compare them with values obtained by a ''maximum internal amplitude'' approach [R. J. LeRoy and R. B. Bernstein, J. Chem. Phys. 54, 5114 (1971)]; and (c) to check the agreement with exact calculations of the B state potential using the ''inverted perturbation approach (IPA).'' The bound and quasibound part of the B 1 Pi/sub u/ state including the locus (R = 8.08 +- 0.05 A) of the barrier maximum (298 +- 8 cm -1 above the adiabatic dissociation limit) is found in excellent agreement with previous results. The shape resonances are not highly sensitive to the long-range interatomic forces, here the repulsive dipole--dipole resonance interaction

  12. Analysis of C-shaped root canal configuration in maxillary molars in a Korean population using cone-beam computed tomography

    Directory of Open Access Journals (Sweden)

    Hyoung-Hoon Jo

    2016-02-01

    Full Text Available Objectives The purpose of this study was to investigate the incidence of root fusion and C-shaped root canals in maxillary molars, and to classify the types of C-shaped canal by analyzing cone-beam computed tomography (CBCT in a Korean population. Materials and Methods Digitized CBCT images from 911 subjects were obtained in Chosun University Dental Hospital between February 2010 and July 2012 for orthodontic treatment. Among them, a total of selected 3,553 data of maxillary molars were analyzed retrospectively. Tomography sections in the axial, coronal, and sagittal planes were displayed by PiViewstar and Rapidia MPR software (Infinitt Co.. The incidence and types of root fusion and C-shaped root canals were evaluated and the incidence between the first and the second molar was compared using Chi-square test. Results Root fusion was present in 3.2% of the first molars and 19.5% of the second molars, and fusion of mesiobuccal and palatal root was dominant. C-shaped root canals were present in 0.8% of the first molars and 2.7% of the second molars. The frequency of root fusion and C-shaped canal was significantly higher in the second molar than the first molar (p < 0.001. Conclusions In a Korean population, maxillary molars showed total 11.3% of root fusion and 1.8% of C-shaped root canals. Furthermore, root fusion and C-shaped root canals were seen more frequently in the maxillary second molars.

  13. Design and optimization of a beam shaping assembly for BNCT based on D-T neutron generator and dose evaluation using a simulated head phantom.

    Science.gov (United States)

    Rasouli, Fatemeh S; Masoudi, S Farhad

    2012-12-01

    A feasibility study was conducted to design a beam shaping assembly for BNCT based on D-T neutron generator. The optimization of this configuration has been realized in different steps. This proposed system consists of metallic uranium as neutron multiplier, TiF(3) and Al(2)O(3) as moderators, Pb as reflector, Ni as shield and Li-Poly as collimator to guide neutrons toward the patient position. The in-air parameters recommended by IAEA were assessed for this proposed configuration without using any filters which enables us to have a high epithermal neutron flux at the beam port. Also a simulated Snyder head phantom was used to evaluate dose profiles due to the irradiation of designed beam. The dose evaluation results and depth-dose curves show that the neutron beam designed in this work is effective for deep-seated brain tumor treatments even with D-T neutron generator with a neutron yield of 2.4×10(12) n/s. The Monte Carlo Code MCNP-4C is used in order to perform these calculations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Mandibular second molar exhibiting a unique "Y-" and "J-" "shaped" root canal anatomy diagnosed using cone-beam computed tomographic scanning: A case report.

    Science.gov (United States)

    Parashar, Saumya-Rajesh; Kowsky, R Dinesh; Natanasabapathy, Velmurugan

    2017-01-01

    This article aims to report a unique case with aberrant root canal anatomy exhibiting "Y-" and "J"-shaped canal pattern in a mandibular second molar. Anatomic complexities may pose challenges for endodontic treatment. Before performing endodontic treatment, the clinician should be aware of the internal anatomy of the tooth being treated and should recognize anatomic aberrations if present. Presence of unusual anatomy may call for modifications in treatment planning. This report describes in detail about a mandibular second molar tooth associated with two paramolar tubercles having a peculiar "Y-" and "J-"shaped canal anatomy detected with the aid of cone beam computed tomography, which has never been reported in the dental literature. The proposed treatment protocol for the endodontic management of the same has also been discussed.

  15. Electrostatic mechanism of shaping the wave micro-relief on the surface of a semiconductor, sputtered by an ion beam

    International Nuclear Information System (INIS)

    Grigor'ev, A.I.

    2000-01-01

    The effect of the electric field formed due to the surface charging, is not accounted for in the weakly-developed theoretical models for the ordered micro-relief formation on the surface of a semiconductor under the impact of an ion beam. It is shown, that the problem on modeling the physical mechanism of forming the ordered wave micro-relief on the semiconductor surface under the impact of a high-energy ion beam may be interpreted as an electrostatic one [ru

  16. Intercostal high intensity focused ultrasound for liver ablation: The influence of beam shaping on sonication efficacy and near-field risks

    Energy Technology Data Exchange (ETDEWEB)

    Greef, M. de, E-mail: m.degreef@umcutrecht.nl; Wijlemans, J. W.; Bartels, L. W.; Moonen, C. T. W.; Ries, M. [Imaging Division, University Medical Center Utrecht, Utrecht 3508GA (Netherlands); Schubert, G.; Koskela, J. [Philips Healthcare, Vantaa FI-01511 (Finland)

    2015-08-15

    Purpose: One of the major issues in high intensity focused ultrasound ablation of abdominal lesions is obstruction of the ultrasound beam by the thoracic cage. Beam shaping strategies have been shown by several authors to increase focal point intensity while limiting rib exposure. However, as rib obstruction leaves only part of the aperture available for energy transmission, conserving total emitted acoustic power, the intensity in the near-field tissues inherently increases after beam shaping. Despite of effective rib sparing, those tissues are therefore subjected to increased risk of thermal damage. In this study, for a number of clinically representative intercostal sonication geometries, modeling clinically available hardware, the effect of beam shaping on both the exposure of the ribs and near-field to acoustic energy was evaluated and the implications for the volumetric ablation rate were addressed. Methods: A relationship between rib temperature rise and acoustic energy density was established by means of in vivo MR thermometry and simulations of the incident acoustic energy for the corresponding anatomies. This relationship was used for interpretation of rib exposure in subsequent numerical simulations in which rib spacing, focal point placement, and the focal point trajectory were varied. The time required to heat a targeted region to 65 °C was determined without and with the application of beam shaping. The required sonication time was used to calculate the acoustic energy density at the fat–muscle interface and at the surface of the ribs. At the fat–muscle interface, exposure was compared to available literature data and rib exposure was interpreted based on the earlier obtained relation between measured temperature rise and simulated acoustic energy density. To estimate the volumetric ablation rate, the cool-down time between periods of energy exposure was estimated using a time-averaged power limit of 100 kJ/h. Results: At the level of the ribs

  17. Beam shaping assembly of a D–T neutron source for BNCT and its dosimetry simulation in deeply-seated tumor

    International Nuclear Information System (INIS)

    Faghihi, F.; Khalili, S.

    2013-01-01

    This article involves two aims for BNCT. First case includes a beam shaping assembly estimation for a D–T neutron source to find epi-thermal neutrons which are the goal in the BNCT. Second issue is the percent depth dose calculation in the adult Snyder head phantom. Monte-Carlo simulations and verification of a suggested beam shaping assembly (including internal neutron multiplier, moderator, filter, external neutron multiplier, collimator, and reflector dimensions) for thermalizing a D–T neutron source as well as increasing neutron flux are carried out and our results are given herein. Finally, we have simulated its corresponding doses for treatment planning of a deeply-seated tumor. - Highlights: ► An assembly for the D–T neutron source including many regions is given herein. ► Dosimetry simulations in the Snyder head phantom for a deeply-seated tumor are carried out. ► Brief literatures conclusions on the recent BNCT studies are presented herein

  18. Production data from a Leica ZBA31H+ shaped e-beam mask writer located at the Photronics facility, Manchester, England

    Science.gov (United States)

    Johnson, Stephen; Loughran, Dominic; Osborne, Peter; Sixt, Pierre; Doering, Hans-Joachim

    1999-06-01

    The ZBA31H+) is a variable shaped spot, vector scan e- beam lithography system operating at 20 keV. The specified performance is designed to produce reticles to 250 nanometer design rules, and beyond. In November 98 the acceptance results of a newly installed Leica ZBA31H+), at Photonic Manchester, were presented in a paper at the VDE/VDI 15th European Conference on Mask Technology. This paper is a continuation of that work and presents data from a capability study carried out, on 4000 angstrom EBR9 HS31 resist. Analysis of: mean to target, uniformity, X/Y bias, isolated vs. dense linewidths, linearity, and registration performance of the tool is presented, and the effects of re- iterative develop on process capability compared. Theoretically, a shaped beam system has advantages over raster scan in terms of write time and edge definition capabilities. In this paper, comparative write times against an Etec Mebes 4500 system are included. The ZBA31H+) has to write very small polygons in order to image non-axial or non-45 degree features. The resulting effect on image quality and write time is investigated. In order to improve the fidelity of small OPC structures, Leica have investigated alternative writing strategies, and their results to data are presented here.

  19. Comparison of canal transportation and centering ability of rotary protaper, one shape system and wave one system using cone beam computed tomography: An in vitro study

    Science.gov (United States)

    Tambe, Varsha Harshal; Nagmode, Pradnya Sunil; Abraham, Sathish; Patait, Mahendra; Lahoti, Pratik Vinod; Jaju, Neha

    2014-01-01

    Aim: The aim of the present study was to compare the canal transportation and centering ability of Rotary ProTaper, One Shape and Wave One systems using cone beam computed tomography (CBCT) in curved root canals to find better instrumentation technique for maintaining root canal geometry. Materials and Methods: Total 30 freshly extracted premolars having curved root canals with at least 10 degrees of curvature were divided into three groups of 10 teeth each. All teeth were scanned by CBCT to determine the root canal shape before instrumentation. In Group 1, the canals were prepared with Rotary ProTaper files, in Group 2 the canals were prepared with One Shape files and in Group 3 canals were prepared with Wave One files. After preparation, post-instrumentation scan was performed. Pre-instrumentation and post-instrumentation images were obtained at three levels, 3 mm apical, 3 mm coronal and 8 mm apical above the apical foramen were compared using CBCT software. Amount of transportation and centering ability were assessed. The three groups were statistically compared with analysis of variance and Tukey honestly significant. Results: All instruments maintained the original canal curvature with significant differences between the different files. Data suggested that Wave One files presented the best outcomes for both the variables evaluated. Wave One files caused lesser transportation and remained better centered in the canal than One Shape and Rotary ProTaper files. Conclusion: The canal preparation with Wave One files showed lesser transportation and better centering ability than One Shape and ProTaper. PMID:25506145

  20. Reagent-Free Programming of Shape-Memory Behavior in Gelatin by Electron Beams: Experiments and Modeling

    Science.gov (United States)

    Riedel, Stefanie; Mayr, Stefan G.

    2018-02-01

    Recent years have seen a paradigm shift in biomaterials toward stimuli-responsive switchable systems that actively interact with their environment. This work demonstrates how to turn the ubiquitous off-the-shelf material gelatin into such a smart biomaterial. This is achieved by realizing the shape-memory effect, viz., a temperature-induced transition from a secondary into a primary shape that has been programmed in the first place merely by exposure to energetic electrons without addition of potentially hazardous cross-linkers. While this scenario is experimentally quantified for exemplary actuators, a theoretical framework capable of unraveling the molecular foundations and predicting experiments is also presented. It particularly employs molecular dynamics modeling based on force fields that are also derived within this work. Implementing this functionality into a highly accepted material, these findings open an avenue for large-scale application in a broad range of areas.

  1. Laser beam welding of NiTi-shape memory alloys; Laserstrahl-Schweissen von NiTi-Formgedaechtnislegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Haas, T.

    1996-04-01

    Using a Nd:YAG laser, the weldability of binary nickel-titanium shape memory alloys containing 50.0 and 48.5 at.-% Ti respectively was investigated. By tensile tests within a temperature range of -80 C to +200 C the mechanical properties of the laser welded joints were examined. Changes in the transformation behaviour were detected by calorimetric measurements (DSC method). The stress-strain behaviour was attributed to the microstructure of the welds, revealed by optical microscopy and transmission electron microscopy (TEM). Using a scanning electron microscope (SEM), the mechanisms of failure were examined. Joints of the martensitic Ti-rich alloy were brittle, showing an ultimate tensile strength of 600 MPa, corresponding to half of the value of the base material. The reduction in strength was explained by the formation of Ti{sub 2}Ni precipitations along grain boundaries in the weld. Since the welds still exhibited twin deformation, pseudoplastic strains of 7% were achieved. Ultimate strength data showed a very low scatter. Therefore it was possible to use the shape memory effect up to a strain of 6% without failure. After a total elongation to 6% strain, the laser welded joints showed a free recovery with an amnesia of 0.3%. The shape memory effect was shown to be retained in the laser welded joints. 154 refs.

  2. A study of optical design and optimization applied to lens module of laser beam shaping of advanced modern optical device

    Science.gov (United States)

    Tsai, Cheng-Mu; Fang, Yi-Chin; Chen, Zhen Hsiang

    2011-10-01

    This study used the aspheric lens to realize the laser flat-top optimization, and applied the genetic algorithm (GA) to find the optimal results. Using the characteristics of aspheric lens to obtain the optimized high quality Nd: YAG 355 waveband laser flat-top optical system, this study employed the Light tools LDS (least damped square) and the GA of artificial intelligence optimization method to determine the optimal aspheric coefficient and obtain the optimal solution. This study applied the aspheric lens with GA for the flattening of laser beams using two aspheric lenses in the aspheric surface optical system to complete 80% spot narrowing under standard deviation of 0.6142.

  3. SU-F-T-183: Design of a Beam Shaping Assembly of a Compact DD-Based Boron Neutron Capture Therapy System

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, M; Liu, Y; Nie, L [Purdue University, West Lafayette, Indiana (United States)

    2016-06-15

    Purpose: To design a beam shaping assembly (BSA) to shape the 2.45-MeV neutrons produced by a deuterium-deuterium (DD) neutron generator and to optimize the beam output for boron neutron capture therapy of brain tumors Methods: MCNP is used for this simulation study. The simulation model consists of a neutron surface source that resembles an actual DD source and is surrounded by a BSA. The neutron source emits 2.45-MeV neutrons isotropically. The BSA is composed of a moderator, reflector, collimator and filter. Various types of materials and geometries are tested for each component to optimize the neutron output. Neutron characteristics are measured with an 2×2×2-cm{sup 3} air-equivalent cylinder at the beam exit. The ideal BSA is determined by evaluating the in-air parameters, which include epithermal neutron per source neutron, fast neutron dose per epithermal neutron, and photon dose per epithermal neutron. The parameter values are compared to those recommended by the IAEA. Results: The ideal materials for reflector and thermal neutron filter were lead and cadmium, respectively. The thickness for reflector was 43 cm and for filter was 0.5 mm. At present, the best-performing moderator has 25 cm of AlF{sub 3} and 5 cm of MgF{sub 2}. This layout creates a neutron spectrum that has a peak at approximately 10 keV and produces 1.35E-4 epithermal neutrons per source neutron per cm{sup 2}. Additional neutron characteristics, fast neutrons per epithermal neutron and photon per epithermal neutron, are still under investigation. Conclusion: Working is ongoing to optimize the final layout of the BSA. The neutron spectrum at the beam exit window of the final configuration will have the maximum number of epithermal neutrons and limited photon and fast neutron contaminations within the recommended values by IAEA. Future studies will also include phantom experiments to validate the simulation results.

  4. A double perturbation method of postbuckling analysis in 2D curved beams for assembly of 3D ribbon-shaped structures

    Science.gov (United States)

    Fan, Zhichao; Hwang, Keh-Chih; Rogers, John A.; Huang, Yonggang; Zhang, Yihui

    2018-02-01

    Mechanically-guided 3D assembly based on controlled, compressive buckling represents a promising, emerging approach for forming complex 3D mesostructures in advanced materials. Due to the versatile applicability to a broad set of material types (including device-grade single-crystal silicon) over length scales from nanometers to centimeters, a wide range of novel applications have been demonstrated in soft electronic systems, interactive bio-interfaces as well as tunable electromagnetic devices. Previously reported 3D designs relied mainly on finite element analyses (FEA) as a guide, but the massive numerical simulations and computational efforts necessary to obtain the assembly parameters for a targeted 3D geometry prevent rapid exploration of engineering options. A systematic understanding of the relationship between a 3D shape and the associated parameters for assembly requires the development of a general theory for the postbuckling process. In this paper, a double perturbation method is established for the postbuckling analyses of planar curved beams, of direct relevance to the assembly of ribbon-shaped 3D mesostructures. By introducing two perturbation parameters related to the initial configuration and the deformation, the highly nonlinear governing equations can be transformed into a series of solvable, linear equations that give analytic solutions to the displacements and curvatures during postbuckling. Systematic analyses of postbuckling in three representative ribbon shapes (sinusoidal, polynomial and arc configurations) illustrate the validity of theoretical method, through comparisons to the results of experiment and FEA. These results shed light on the relationship between the important deformation quantities (e.g., mode ratio and maximum strain) and the assembly parameters (e.g., initial configuration and the applied strain). This double perturbation method provides an attractive route to the inverse design of ribbon-shaped 3D geometries, as

  5. Diode-pumped, single frequency Nd:YLF laser for 60-beam OMEGA laser pulse-shaping system

    International Nuclear Information System (INIS)

    Okishev, A.V.; Seka, W.

    1997-01-01

    The operational conditions of the OMEGA pulse-shaping system require an extremely reliable and low-maintenance master oscillator. The authors have developed a diode-pumped, single-frequency, pulsed Nd:YLF laser for this application. The laser generates Q-switched pulses of ∼160-ns duration and ∼10-microJ energy content at the 1,053-nm wavelength with low amplitude fluctuations (<0.6% rms) and low temporal jitter (<7 ns rms). Amplitude and frequency feedback stabilization systems have been used for high long-term amplitude and frequency stability

  6. Numerical computation of space-charge fields of electron bunches in a beam pipe of elliptical shape

    International Nuclear Information System (INIS)

    Markovik, A.

    2005-01-01

    This work deals in particularly with 3D numerical simulations of space-charge fields from electron bunches in a beam pipe with elliptical cross-section. To obtain the space-charge fields it is necessary to calculate the Poisson equation with given boundary condition and space charge distribution. The discretization of the Poisson equation by the method of finite differences on a Cartesian grid, as well as setting up the coefficient matrix A for the elliptical domain are explained in the section 2. In the section 3 the properties of the coefficient matrix and possible numerical algorithms suitable for solving non-symmetrical linear systems of equations are introduced. In the following section 4, the applied solver algorithms are investigated by numerical tests with right hand side function for which the analytical solution is known. (orig.)

  7. Numerical computation of space-charge fields of electron bunches in a beam pipe of elliptical shape

    Energy Technology Data Exchange (ETDEWEB)

    Markovik, A.

    2005-09-28

    This work deals in particularly with 3D numerical simulations of space-charge fields from electron bunches in a beam pipe with elliptical cross-section. To obtain the space-charge fields it is necessary to calculate the Poisson equation with given boundary condition and space charge distribution. The discretization of the Poisson equation by the method of finite differences on a Cartesian grid, as well as setting up the coefficient matrix A for the elliptical domain are explained in the section 2. In the section 3 the properties of the coefficient matrix and possible numerical algorithms suitable for solving non-symmetrical linear systems of equations are introduced. In the following section 4, the applied solver algorithms are investigated by numerical tests with right hand side function for which the analytical solution is known. (orig.)

  8. The effects of vacuum induction melting and electron beam melting techniques on the purity of NiTi shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Otubo, J. [Instituto Tecnologico de Aeronautica (ITA), 12228-900 S.J. Campos, SP (Brazil) and DEMA-FEM-UNICAMP, 13083-000 Campinas, SP (Brazil)]. E-mail: jotubo@ita.br; Rigo, O.D. [DEMA-FEM-UNICAMP, 13083-000 Campinas, SP (Brazil); Neto, C. Moura [Instituto Tecnologico de Aeronautica (ITA), 12228-900 S.J. Campos, SP (Brazil); Mei, P.R. [DEMA-FEM-UNICAMP, 13083-000 Campinas, SP (Brazil)

    2006-11-25

    The usual process to produce NiTi shape memory alloys is by vacuum induction melting (VIM) using graphite crucible that contaminates the bath with carbon. The contamination by oxygen comes from residual oxygen inside the melting chamber. A new alternative process to produce NiTi alloys is by electron beam melting (EBM) using water-cooled copper crucible that eliminates the carbon contamination and the oxygen contamination would be minimized due to operation in high vacuum. This work compares the two processes and shows that the carbon contamination is four to ten times lower for EBM compared to VIM products and that the final oxygen content is much more dependent on the starting raw materials. The purity of the final product should be very important mainly in terms of biomedical applications and the contaminations by carbon and oxygen affect the direct and reverse martensitic transformation temperatures.

  9. The Effect of Collimating Lens Focusing on Laser Beam Shape in Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS).

    Science.gov (United States)

    O'Rourke, Matthew B; Raymond, Benjamin B A; Djordjevic, Steven P; Padula, Matthew P

    2018-03-01

    Tissue imaging using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a well-established technique that, in recent years, has seen wider adoption and novel application. Applications such imaging mass spectrometry (IMS) and biotyping are beginning to gain greater exposure and use; however, with limitations in optimization methods, producing the best result often relies on the ability to customize the physical characteristics of the instrumentation, a task that is challenging for most mass spectrometry laboratories. With this in mind, we have described the effect of making simple adjustments to the laser optics at the final collimating lens area, to adjust the laser beam size and shape in order to allow greater customization of the instrument for improving techniques such as IMS. We have therefore been able to demonstrate that improvements can be made without requiring the help of an electrical engineer or external funding in a way that only costs a small amount of time. Graphical Abstract ᅟ.

  10. High electron mobility through the edge states in random networks of c-axis oriented wedge-shaped GaN nanowalls grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Bhasker, H. P.; Dhar, S.; Sain, A.; Kesaria, Manoj; Shivaprasad, S. M.

    2012-01-01

    Transport and optical properties of random networks of c-axis oriented wedge-shaped GaN nanowalls grown spontaneously on c-plane sapphire substrates through molecular beam epitaxy are investigated. Our study suggests a one dimensional confinement of carriers at the top edges of these connected nanowalls, which results in a blue shift of the band edge luminescence, a reduction of the exciton-phonon coupling, and an enhancement of the exciton binding energy. Not only that, the yellow luminescence in these samples is found to be completely suppressed even at room temperature. All these changes are highly desirable for the enhancement of the luminescence efficiency of the material. More interestingly, the electron mobility through the network is found to be significantly higher than that is typically observed for GaN epitaxial films. This dramatic improvement is attributed to the transport of electrons through the edge states formed at the top edges of the nanowalls.

  11. An innovative approach to achieve re-centering and ductility of cement mortar beams through randomly distributed pseudo-elastic shape memory alloy fibers

    Science.gov (United States)

    Shajil, N.; Srinivasan, S. M.; Santhanam, M.

    2012-04-01

    Fibers can play a major role in post cracking behavior of concrete members, because of their ability to bridge cracks and distribute the stress across the crack. Addition of steel fibers in mortar and concrete can improve toughness of the structural member and impart significant energy dissipation through slow pull out. However, steel fibers undergo plastic deformation at low strain levels, and cannot regain their shape upon unloading. This is a major disadvantage in strong cyclic loading conditions, such as those caused by earthquakes, where self-centering ability of the fibers is a desired characteristic in addition to ductility of the reinforced cement concrete. Fibers made from an alternative material such as shape memory alloy (SMA) could offer a scope for re-centering, thus improving performance especially after a severe loading has occurred. In this study, the load-deformation characteristics of SMA fiber reinforced cement mortar beams under cyclic loading conditions were investigated to assess the re-centering performance. This study involved experiments on prismatic members, and related analysis for the assessment and prediction of re-centering. The performances of NiTi fiber reinforced mortars are compared with mortars with same volume fraction of steel fibers. Since re-entrant corners and beam columns joints are prone to failure during a strong ground motion, a study was conducted to determine the behavior of these reinforced with NiTi fiber. Comparison is made with the results of steel fiber reinforced cases. NiTi fibers showed significantly improved re-centering and energy dissipation characteristics compared to the steel fibers.

  12. Optimization of a beam shaping bolus for superficial microwave hyperthermia waveguide applicators using a finite element method

    International Nuclear Information System (INIS)

    Kumaradas, J Carl; Sherar, Michael D

    2003-01-01

    Temperature inhomogeneity in hyperthermia treatments often limits the total thermal dose that can be delivered to the tumour region. To reduce such inhomogeneities, a prototype dynamically modifiable square array of saline-filled patches which attenuate microwave energy was developed for superficial treatments that use external microwave applicators. The array was situated inside the coupling water bolus that is often used with external applicators. The prototype has been previously tested clinically with promising results. A more complete theoretical analysis of the performance of this new bolus design and improvements to its design by modelling are presented here. The analysis was performed by performing five iterative simulations of the SAR pattern produced inside a tissue structure by a waveguide applicator with a water bolus containing the dynamic patch array attached. Between iterations the patch array configuration was modified in an attempt to improve the ability of the bolus to confine heating to an 'L'-shaped tumour region. These simulations were performed using the finite element method. The steady-state temperature profile was then computed using a finite element method based simulation of heat transfer that assumed a given applicator power level and water bolus temperature. Several iterations of these heat transfer simulations were performed with varying applicator power level and water bolus temperature to improve the confinement of heating to the target region. The analysis showed that the dynamic patch array should be capable of conforming heating to an 'L'-shaped target tumour region while limiting the heating to the surrounding normal tissue to an acceptable level

  13. The formation of hexagonal-shaped InGaN-nanodisk on GaN-nanowire observed in plasma source molecular beam epitaxy

    KAUST Repository

    Ng, Tien Khee

    2014-03-08

    We report on the properties and growth kinetics of defect-free, photoluminescence (PL) efficient mushroom-like nanowires (MNWs) in the form of ~30nm thick hexagonal-shaped InGaN-nanodisk on GaN nanowires, coexisting with the conventional rod-like InGaN-on-GaN nanowires (RNWs) on (111)-silicon-substrate. When characterized using confocal microscopy (CFM) with 458nm laser excitation, while measuring spontaneous-emission at fixed detection wavelengths, the spatial intensity map evolved from having uniform pixelated emission, to having only an emission ring, and then a round emission spot. This corresponds to the PL emission with increasing indium composition; starting from emission mainly from the RNW, and then the 540 nm emission from one MNWs ensemble, followed by the 590 nm emission from a different MNW ensemble, respectively. These hexagonal-shaped InGaN-nano-disks ensembles were obtained during molecular-beam-epitaxy (MBE) growth. On the other hand, the regular rod-like InGaN-on-GaN nanowires (RNWs) were emitting at a shorter peak wavelength of 490 nm. While the formation of InGaN rod-like nanowire is well-understood, the formation of the hexagonal-shaped InGaN-nanodisk-on-GaN-nanowire requires further investigation. It was postulated to arise from the highly sensitive growth kinetics during plasma-assisted MBE of InGaN at low temperature, i.e. when the substrate temperature was reduced from 800 °C (GaN growth) to <600 °C (InGaN growth), during which sparsely populated metal-droplet formation prevails and further accumulated more indium adatoms due to a higher cohesive bond between metallic molecules. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  14. Vacuum isostatic micro/macro molding of PTFE materials for laser beam shaping in environmental applications: large scale UV laser water purification

    Science.gov (United States)

    Lizotte, Todd; Ohar, Orest

    2009-08-01

    Accessibility to fresh clean water has determined the location and survival of civilizations throughout the ages [1]. The tangible economic value of water is demonstrated by industry's need for water in fields such as semiconductor, food and pharmaceutical manufacturing. Economic stability for all sectors of industry depends on access to reliable volumes of good quality water. As can be seen on television a nation's economy is seriously affected by water shortages through drought or mismanagement and as such those water resources must therefore be managed both for the public interest and the economic future. For over 50 years ultraviolet water purification has been the mainstay technology for water treatment, killing potential microbiological agents in water for leisure activities such as swimming pools to large scale waste water treatment facilities where the UV light photo-oxidizes various pollutants and contaminants. Well tailored to the task, UV provides a cost effective way to reduce the use of chemicals in sanitization and anti-biological applications. Predominantly based on low pressure Hg UV discharge lamps, the system is plagued with lifetime issues (~1 year normal operation), the last ten years has shown that the technology continues to advance and larger scale systems are turning to more advanced lamp designs and evaluating solidstate UV light sources and more powerful laser sources. One of the issues facing the treatment of water with UV lasers is an appropriate means of delivering laser light efficiently over larger volumes or cross sections of water. This paper examines the potential advantages of laser beam shaping components made from isostatically micro molding microstructured PTFE materials for integration into large scale water purification and sterilization systems, for both lamps and laser sources. Applying a unique patented fabrication method engineers can form micro and macro scale diffractive, holographic and faceted reflective structures

  15. Monte Carlo study for designing a dedicated “D”-shaped collimator used in the external beam radiotherapy of retinoblastoma patients

    Energy Technology Data Exchange (ETDEWEB)

    Mayorga, P. A. [FISRAD S.A.S., CR 64 A No. 22 - 41, Bogotá D C, Colombia and Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Brualla, L.; Sauerwein, W. [NCTeam, Strahlenklinik, Universitätsklinikum Essen, Hufelandstraße 55, D-45122 Essen (Germany); Lallena, A. M., E-mail: lallena@ugr.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)

    2014-01-15

    Purpose: Retinoblastoma is the most common intraocular malignancy in the early childhood. Patients treated with external beam radiotherapy respond very well to the treatment. However, owing to the genotype of children suffering hereditary retinoblastoma, the risk of secondary radio-induced malignancies is high. The University Hospital of Essen has successfully treated these patients on a daily basis during nearly 30 years using a dedicated “D”-shaped collimator. The use of this collimator that delivers a highly conformed small radiation field, gives very good results in the control of the primary tumor as well as in preserving visual function, while it avoids the devastating side effects of deformation of midface bones. The purpose of the present paper is to propose a modified version of the “D”-shaped collimator that reduces even further the irradiation field with the scope to reduce as well the risk of radio-induced secondary malignancies. Concurrently, the new dedicated “D”-shaped collimator must be easier to build and at the same time produces dose distributions that only differ on the field size with respect to the dose distributions obtained by the current collimator in use. The scope of the former requirement is to facilitate the employment of the authors' irradiation technique both at the authors' and at other hospitals. The fulfillment of the latter allows the authors to continue using the clinical experience gained in more than 30 years. Methods: The Monte Carlo codePENELOPE was used to study the effect that the different structural elements of the dedicated “D”-shaped collimator have on the absorbed dose distribution. To perform this study, the radiation transport through a Varian Clinac 2100 C/D operating at 6 MV was simulated in order to tally phase-space files which were then used as radiation sources to simulate the considered collimators and the subsequent dose distributions. With the knowledge gained in that study, a new

  16. Analysis of C-shaped canal systems in mandibular second molars using surgical operating microscope and cone beam computed tomography: A clinical approach.

    Science.gov (United States)

    Chhabra, Sanjay; Yadav, Seema; Talwar, Sangeeta

    2014-05-01

    The study was aimed to acquire better understanding of C-shaped canal systems in mandibular second molar teeth through a clinical approach using sophisticated techniques such as surgical operating microscope and cone beam computed tomography (CBCT). A total of 42 extracted mandibular second molar teeth with fused roots and longitudinal grooves were collected randomly from native Indian population. Pulp chamber floors of all specimens were examined under surgical operating microscope and classified into four types (Min's method). Subsequently, samples were subjected to CBCT scan after insertion of K-files size #10 or 15 into each canal orifice and evaluated using the cross-sectional and 3-dimensional images in consultation with dental radiologist so as to obtain more accurate results. Minimum distance between the external root surface on the groove and initial file placed in the canal was also measured at different levels and statistically analyzed. Out of 42 teeth, maximum number of samples (15) belonged to Type-II category. A total of 100 files were inserted in 86 orifices of various types of specimens. Evaluation of the CBCT scan images of the teeth revealed that a total of 21 canals were missing completely or partially at different levels. The mean values for the minimum thickness were highest at coronal followed by middle and apical third levels in all the categories. Lowest values were obtained for teeth with Type-III category at all three levels. The present study revealed anatomical variations of C-shaped canal system in mandibular second molars. The prognosis of such complex canal anatomies can be improved by simultaneous employment of modern techniques such as surgical operating microscope and CBCT.

  17. In-vitro Assessing the Shaping Ability of Three Nickel-Titanium Rotary Single File Systems by Cone Beam Computed Tomography

    Directory of Open Access Journals (Sweden)

    Ali Imad Al-Asadi

    2018-02-01

    Full Text Available Aim of the study was to evaluate the canal transportation and centering ability of three nickel-titanium single file rotary systems by cone beam computed tomography (CBCT. Materials and methods: Thirty permanent maxillary first molar with a range of mesiobuccal canals curvature from 20-30 degree were selected and assigned into three groups (n=10, according to the biomechanical preparation system used: Hyflex EDM (HF, Reciproc blue (RB and OneShape (OS. The sampled were scanned by CBCT after being mounted on customized acrylic base and then rescanned after the instrumentation. Slices from the axial section were taken from both exposures at 3 mm, 6 mm and 9 mm from the root apex corresponding to the apical, middle, and coronal third respectively. Data were statistically analyzed using Kurskal-Wallis and Mann-Whitney U tests at the 5% confidence level. Results: The results showed that there were no significant differences at the apical and coronal third and a significant difference at the middle third regarding canal transportation. However, there was a significant difference at the apical third and no significant difference at the middle and coronal third regarding centering ratio. Conclusion: It was concluded that the three single rotary systems reported a degree in canal transportation and centric ratio but the Hyflex EDM reported the least one.

  18. Shaping ability of reciprocating motion of WaveOne and HyFlex in moderate to severe curved canals: A comparative study with cone beam computed tomography

    Science.gov (United States)

    Simpsy, Gurram Samuel; Sajjan, Girija S.; Mudunuri, Padmaja; Chittem, Jyothi; Prasanthi, Nalam N. V. D.; Balaga, Pankaj

    2016-01-01

    Introduction: M-Wire and reciprocating motion of WaveOne and controlled memory (CM) wire) of HyFlex were the recent innovations using thermal treatment. Therefore, a study was planned to evaluate the shaping ability of reciprocating motion of WaveOne and HyFlex using cone beam computed tomography (CBCT). Methodology: Forty-five freshly extracted mandibular teeth were selected and stored in saline until use. All teeth were scanned pre- and post-operatively using CBCT (Kodak 9000). All teeth were accessed and divided into three groups. (1) Group 1 (control n = 15): Instrumented with ProTaper. (2) Group 2 (n = 15): Instrumented with primary file (8%/25) WaveOne. (3) Group 3 (n = 15): Instrumented with (4%/25) HyFlex CM. Sections at 1, 3, and 5 mm were obtained from the pre- and post-operative scans. Measurement was done using CS3D software and Adobe Photoshop software. Apical transportation and degree of straightening were measured and statistically analyzed. Results: HyFlex showed lesser apical transportation when compared to other groups at 1 and 3 mm. WaveOne showed lesser degree of straightening when compared to other groups. Conclusion: This present study concluded that all systems could be employed in routine endodontics whereas HyFlex and WaveOne could be employed in severely curved canals. PMID:27994323

  19. Transport and optical properties of c-axis oriented wedge shaped GaN nanowall network grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Bhasker, H. P.; Dhar, S. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra-400076 (India); Thakur, Varun; Kesaria, Manoj; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Bangalore- 560064 (India)

    2014-02-21

    The transport and optical properties of wedge-shaped nanowall network of GaN grown spontaneously on cplane sapphire substrate by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) show interesting behavior. The electron mobility at room temperature in these samples is found to be orders of magnitude higher than that of a continuous film. Our study reveals a strong correlation between the mobility and the band gap in these nanowall network samples. However, it is seen that when the thickness of the tips of the walls increases to an extent such that more than 70% of the film area is covered, it behaves close to a flat sample. In the sample with lower surface coverage (≈40% and ≈60%), it was observed that the conductivity, mobility as well as the band gap increase with the decrease in the average tip width of the walls. Photoluminescence (PL) experiments show a strong and broad band edge emission with a large (as high as ≈ 90 meV) blue shift, compared to that of a continuous film, suggesting a confinement of carriers on the top edges of the nanowalls. The PL peak width remains wide at all temperatures suggesting the existence of a high density of tail states at the band edge, which is further supported by the photoconductivity result. The high conductivity and mobility observed in these samples is believed to be due to a “dissipation less” transport of carriers, which are localized at the top edges (edge states) of the nanowalls.

  20. Skull Bone Defects Reconstruction with Custom-Made Titanium Graft shaped with Electron Beam Melting Technology: Preliminary Experience in a Series of Ten Patients.

    Science.gov (United States)

    Francaviglia, Natale; Maugeri, Rosario; Odierna Contino, Antonino; Meli, Francesco; Fiorenza, Vito; Costantino, Gabriele; Giammalva, Roberto Giuseppe; Iacopino, Domenico Gerardo

    2017-01-01

    Cranioplasty represents a challenge in neurosurgery. Its goal is not only plastic reconstruction of the skull but also to restore and preserve cranial function, to improve cerebral hemodynamics, and to provide mechanical protection of the neural structures. The ideal material for the reconstructive procedures and the surgical timing are still controversial. Many alloplastic materials are available for performing cranioplasty and among these, titanium still represents a widely proven and accepted choice. The aim of our study was to present our preliminary experience with a "custom-made" cranioplasty, using electron beam melting (EBM) technology, in a series of ten patients. EBM is a new sintering method for shaping titanium powder directly in three-dimensional (3D) implants. To the best of our knowledge this is the first report of a skull reconstruction performed by this technique. In a 1-year follow-up no postoperative complications have been observed and good clinical and esthetic outcomes were achieved. Costs higher than those for other types of titanium mesh, a longer production process, and the greater expertise needed for this technique are compensated by the achievement of most complex skull reconstructions with a shorter operative time.

  1. Influence of plasma-induced energy deposition effects, the equation of state, thermal ionization, pulse shaping, and radiation on ion-beam-driven expansions of plane metal targets

    International Nuclear Information System (INIS)

    Long, K.A.; Tahir, N.A.

    1986-01-01

    In a previous paper by Long and Tahir [Phys. Fluids 29, 275 (1986)], the motion of plane targets irradiated by ion beams whose energy deposition was assumed to be independent of the ion energy, and the temperature and density of the plasma, was analyzed. In this paper, the analytic solution is extended in order to include the effects of a temperature-and density-dependent energy deposition as a result of electron excitation, an improved equation of state, thermal ionization, a pulse shape, and radiation losses. The change in the energy deposition with temperature and density leads to range shortening and an increased power deposition in the target. It is shown how the analytic theory can be used to analyze experiments to measure the enhanced energy deposition. In order to further analyze experiments, numerical simulations are presented which include the plasma-induced effects on the energy deposition. It is shown that since the change in the range is due to both decrease in density and the increase in temperature, it is not possible to separate these two effects in present experiments. Therefore, the experiments which measure the time-dependent energy of the ions emerging from the back side of a plane target do not as yet measure the energy loss as a function of the density and temperature of the plasma or of the energy of the ion, but only an averaged loss over certain ranges of these physical quantities

  2. Transport and optical properties of c-axis oriented wedge shaped GaN nanowall network grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Bhasker, H. P.; Dhar, S.; Thakur, Varun; Kesaria, Manoj; Shivaprasad, S. M.

    2014-01-01

    The transport and optical properties of wedge-shaped nanowall network of GaN grown spontaneously on cplane sapphire substrate by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) show interesting behavior. The electron mobility at room temperature in these samples is found to be orders of magnitude higher than that of a continuous film. Our study reveals a strong correlation between the mobility and the band gap in these nanowall network samples. However, it is seen that when the thickness of the tips of the walls increases to an extent such that more than 70% of the film area is covered, it behaves close to a flat sample. In the sample with lower surface coverage (≈40% and ≈60%), it was observed that the conductivity, mobility as well as the band gap increase with the decrease in the average tip width of the walls. Photoluminescence (PL) experiments show a strong and broad band edge emission with a large (as high as ≈ 90 meV) blue shift, compared to that of a continuous film, suggesting a confinement of carriers on the top edges of the nanowalls. The PL peak width remains wide at all temperatures suggesting the existence of a high density of tail states at the band edge, which is further supported by the photoconductivity result. The high conductivity and mobility observed in these samples is believed to be due to a “dissipation less” transport of carriers, which are localized at the top edges (edge states) of the nanowalls

  3. Cold-fluid theory of equilibrium and stability of a high-intensity periodically twisted ellipse-shaped charged-particle beam

    Directory of Open Access Journals (Sweden)

    Jing Zhou

    2006-03-01

    Full Text Available It is shown that there exists an exact paraxial cold-fluid equilibrium of a high-intensity, space-charge-dominated charged-particle beam with a periodically twisted elliptic cross section in a nonaxisymmetric periodic magnetic field. Generalized envelope equations, which determine the beam envelopes, ellipse orientation, density, and internal flow velocity profiles, are derived. Nonrelativistic and relativistic examples of such beam equilibria are presented. The equilibrium and stability of such beams are demonstrated by self-consistent particle-in-cell (PIC simulations.

  4. Beam-Beam Effects

    International Nuclear Information System (INIS)

    Herr, W; Pieloni, T

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities

  5. Regression and statistical shape model based substitute CT generation for MRI alone external beam radiation therapy from standard clinical MRI sequences

    Science.gov (United States)

    Ghose, Soumya; Greer, Peter B.; Sun, Jidi; Pichler, Peter; Rivest-Henault, David; Mitra, Jhimli; Richardson, Haylea; Wratten, Chris; Martin, Jarad; Arm, Jameen; Best, Leah; Dowling, Jason A.

    2017-11-01

    In MR only radiation therapy planning, generation of the tissue specific HU map directly from the MRI would eliminate the need of CT image acquisition and may improve radiation therapy planning. The aim of this work is to generate and validate substitute CT (sCT) scans generated from standard T2 weighted MR pelvic scans in prostate radiation therapy dose planning. A Siemens Skyra 3T MRI scanner with laser bridge, flat couch and pelvic coil mounts was used to scan 39 patients scheduled for external beam radiation therapy for localized prostate cancer. For sCT generation a whole pelvis MRI (1.6 mm 3D isotropic T2w SPACE sequence) was acquired. Patients received a routine planning CT scan. Co-registered whole pelvis CT and T2w MRI pairs were used as training images. Advanced tissue specific non-linear regression models to predict HU for the fat, muscle, bladder and air were created from co-registered CT-MRI image pairs. On a test case T2w MRI, the bones and bladder were automatically segmented using a novel statistical shape and appearance model, while other soft tissues were separated using an Expectation-Maximization based clustering model. The CT bone in the training database that was most ‘similar’ to the segmented bone was then transformed with deformable registration to create the sCT component of the test case T2w MRI bone tissue. Predictions for the bone, air and soft tissue from the separate regression models were successively combined to generate a whole pelvis sCT. The change in monitor units between the sCT-based plans relative to the gold standard CT plan for the same IMRT dose plan was found to be 0.3%+/-0.9% (mean  ±  standard deviation) for 39 patients. The 3D Gamma pass rate was 99.8+/-0.00 (2 mm/2%). The novel hybrid model is computationally efficient, generating an sCT in 20 min from standard T2w images for prostate cancer radiation therapy dose planning and DRR generation.

  6. Desain Beam Shaping Assembly (BSA berbasis D-D Neutron Generator 2,45 MeV untuk Uji Fasilitas BNCT

    Directory of Open Access Journals (Sweden)

    Desman P. Gulo

    2015-12-01

    Full Text Available Boron Neutron Capture Therapy (BNCT is one of the cancer treatments that are being developed in nowadays. In order to support BNCT treatment for cancer that exists in underneath skin like breast cancer, the facility needs a generator that is able to produce epithermal neutron. One of the generator that is able to produce neutron is D-D neutron generator with 2.45 MeV energy. Based on the calculation of this paper, we found that the total production of neutron per second (neutron yield from Neutron Generator (NG by PSTA-BATAN Yogyakarta is 2.55×1011 n/s. The energy and flux that we found is in the range of quick neutron. Thus, it needs to be moderated to the level of epithermal neutron which is located in the interval energy of 1 eV to 10 KeV with 109 n/cm2s flux. This number is the recommendation standard from IAEA. Beam Shaping Assembly (BSA is needed in order to moderate the quick neutron to the level of epithermal neutron. One part of BSA that has the responsibility in moderating the quick neutron to epithermal neutron is the moderator. The substance of moderator used in this paper is MgF2 and A1F3. The thickness of moderator has been set in in such a way by using MCNPX software in order to fulfill the standard of IAEA. As the result of optimizing BSA moderator, the data obtain epithermal flux with the total number of 4.64×108 n/cm2/s for both of moderators with the thickness of moderator up to 15 cm. At the end of this research, the number of epithermal flux does not follow the standard of IAEA. This is because the flux neutron that is being produced by NG is relatively small. In conclusion, the NG from PSTA-BATAN Yogyakarta is not ready to be used for the BNCT treatment facility for the underneath skin cancer like breast cancer.

  7. An Electromagnetic Beam Converter

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...

  8. Shapes of leaves with parallel venation. Modelling of the Epipactis sp. (Orchidaceae) leaves with the help of a system of coupled elastic beams

    OpenAIRE

    Jakubska-Busse, Anna; Janowicz, Maciej; Ochnio, Luiza; Jackowska-Zduniak, Beata

    2016-01-01

    Static properties of leaves with parallel venation, with particular emphasis on the genus EpipactisZinn, 1757 (Orchidaceae, Neottieae) have been modelled with coupled quasi-parallel elastic “beams.” The non-linear theory of strongly bended beams have been employed. The resulting boundary-value problem has been solved numerically with the help of the finite-difference method. Possible dislocations resulting in additional Dirac-delta like forces have been take into account. Morphological simila...

  9. FRECUENCIAS NATURALES EN VIGAS ACTIVAMENTE TORSIONADAS USANDO ALAMBRES DE ALEACIÓN CON MEMORIA DE FORMA (SMA | NATURAL FREQUENCIES IN ACTVELY TWISTED BEAMS USING SHAPE MEMORY ALLOY (SMA WIRES

    Directory of Open Access Journals (Sweden)

    Gaetano Starlacci

    2016-08-01

    Full Text Available Changes in the geometry and stiffness of structural members can be obtained using Shape Memory Alloys (SMA wires, previously stretched, and externally attached to the member in a helical pattern. The wire was modeled assuming transformation from a pure martensitic phase to a pure austenitic phase. Natural frequency values before and after the SMA wire activation attached to the beam were calculated using the finite element method and these values were compared with those obtained from a model developed for pre-twisted stress-free cantilever members. The results obtained showed the active torsion influence over the structural element in the values of natural frequencies calculated.

  10. Shapes of leaves with parallel venation. Modelling of the Epipactis sp. (Orchidaceae leaves with the help of a system of coupled elastic beams

    Directory of Open Access Journals (Sweden)

    Anna Jakubska-Busse

    2016-06-01

    Full Text Available Static properties of leaves with parallel venation, with particular emphasis on the genus EpipactisZinn, 1757 (Orchidaceae, Neottieae have been modelled with coupled quasi-parallel elastic “beams.” The non-linear theory of strongly bended beams have been employed. The resulting boundary-value problem has been solved numerically with the help of the finite-difference method. Possible dislocations resulting in additional Dirac-delta like forces have been take into account. Morphological similarity of the model and real leaves has been obtained. In particular, the concentrated forces have been shown to cause undulation in the leaves.

  11. Design and optimization of a beam-shaping assembly (BSA) for BNCT based on a neutron generator located at CEADEN, Havana, Cuba

    International Nuclear Information System (INIS)

    Padilla Cabal, F.; Martin, G; Abrahantes, A.

    2007-01-01

    A monoenergetic neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of Boron Neutron Capture Therapy (BNCT). Two figures-of-merit, i.e. the absorbed dose for healthy tissue and the absorbed tumor dose at a given depth in the brain are used to measure the neutron beam quality. Also irradiation time, therapeutic gain and the power generated in the target are utilized as beam assessment parameters. Moderators, reflectors and delimiters are designed and optimized to moderate the high-energy neutrons from the fusion reactions 2 H(d;n) 3 He and 3 H(d;n) 4 He down to a suitable energy spectrum. Metallic uranium and manganese are successfully tested for fast-to-epithermal neutron moderation as well as Fluental TM for the neutron spectrum shifting. A semispherical target is proposed in order to dissipate twice the amount of power generated in the target, and decrease all the dimensions of the BSA. The cooling system of the target is also included in the calculations. Calculations are performed using the MCNP code. After the optimization of our beam-shaper a study of the dose distribution in the head had been made. The therapeutic gain is increased in 9% while the current required for one hour treatment is decreased in comparison with the trading prototypes of NG used for BNCT. (Author)

  12. Design and optimization of a beam-shaping assembly (BSA) for BNCT based on a neutron generator located at CEADEN, Havana, Cuba

    International Nuclear Information System (INIS)

    Padilla Cabal, F.; Martin, G.; Abrahantes, A.

    2007-01-01

    A monoenergetic neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of Boron Neutron Capture Therapy (BNCT). Two figures-of-merit, i.e. the absorbed dose for healthy tissue and the absorbed tumor dose at a given depth in the brain are used to measure the neutron beam quality. Also irradiation time, therapeutic gain and the power generated in the target are utilized as beam assessment parameters. Moderators, reflectors and delimiters are designed and optimized to moderate the high-energy neutrons from the fusion reactions 2 H(d;n) 3 He and 3 H(d;n) 4 Hedown to a suitable energy spectrum. Metallic uranium and manganese are successfully tested for fast-to-epithermal neutron moderation as well as Fluental TM for the neutron spectrum shifting. A semi spherical target is proposed in order to dissipate twice the amount of power generated in the target, and decrease all the dimensions of the BSA. The cooling system of the target is also included in the calculations. Calculations are performed using the MCNP code. After the optimization of our beam-shaper a study of the dose distribution in the head had been made. The therapeutic gain is increased in 9% while the current required for one hour treatment is decreased in comparison with the trading prototypes of NG used for BNCT. (Author)

  13. 3D characterization of the forces in optical traps based on counter-propagation beams shaped by a spatial light modulator

    DEFF Research Database (Denmark)

    Kristensen, M. V.; Lindballe, T.; Kylling, A.

    2010-01-01

    An experimental characterization of the 3D forces, acting on a trapped polystyrene bead in a counter-propagating beam geometry, is reported. Using a single optical trap with a large working distance (in the BioPhotonics Workstation), we simultaneously measure the transverse and longitudinal...... trapping force constants. Two different methods were used: The Drag force method and the Equipartition method. We show that the counterpropagating beams traps are simple harmonic for small displacements. The force constants reveal a transverse asymmetry as - = 9.7 pN/µm and + = 11.3 pN/µm (at a total laser...... power of 2x35 mW) for displacements in opposite directions. The Equipartition method is limited by mechanical noise and is shown to be applicable only when the total laser power in a single 10 µm counter-propagating trap is below 2x20 mW....

  14. On the H8 beam line of the SPS in the North Area, a complete slice of the ATLAS detector is taking shape

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    The Inner Detector and Calorimetry setup. The Liquid Argon electromagnetic calorimeter in its cryostat, and the tile calorimeter (centre) are mounted such that they can be repositioned in the beam, which travels from left to right. Also visible is the magnet housing the Pixel and SCT detectors (far left), the Transition Radiation Tracker (left) and part of a MDT/RPC Muon chamber (far right).

  15. Study on the conditions of proton beam shaping in the ion source of the AN USSR IYaI meson factory

    International Nuclear Information System (INIS)

    Esin, S.K.; Yakushev, V.P.; Frolov, O.T.; Polulyakh, V.P.

    1981-01-01

    The results of measuring proton beam emittance in ion source- duaplasmatron with tungsten-barium direct-heated cathode intended for 750 keV injector of the linear accelerator are presented. The system of ion extraction comprises an expander and extraction grid. Peculiarities of primary beam formation at different configurations of the expander: a) expander in the form of a cylinder, b) comical expander, c) the same conical expander but with a splitter installed behind the anode window and permitting to cut off the central part of plasma flux; ''sectional'' expander made of 5 separated from one another similar metal rings of 16 mm height fixed in the cylinder made of insulator, are studied. The diameter of the duaplasmatron window equals 0.8 mm. It is shown that beam formation with the help of cylindrical and conical with a splitter expanders meet the requirements of the proton injector and well satisfy the aperture of the channel of the accelerating tube of 54 mm diameter [ru

  16. High-Performance Wireless via the Merger of CI Chip-Shaped DS-CDMA and Oscillating-Beam Smart Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Nassar Carl R

    2004-01-01

    Full Text Available We introduce a novel merger of direct sequence code division multiple access (DS-CDMA and smart antenna arrays. With regard to the DS-CDMA scheme, we employ carrier interferometry DS-CDMA (CI/DS-CDMA, a novel implementation of DS-CDMA where chips are decomposable into narrowband frequency components. With regard to the antenna array, we deploy the oscillating-beam smart array. Here, applying proper time-varying phases to the array elements, we create small movement (oscillation in the antenna array's pattern, while steering the antenna pattern main lobe to the position of the intended user. The oscillating antenna pattern creates a time-varying channel with a controllable coherence time. This, in turn, provides transmit diversity in the form of a time diversity gain at the mobile receiver side. At the receiver, three stages of combining are available: combining time components of the received signal within symbol duration (each experiencing a different fade to enhance performance via time diversity; combining frequency components which make up the CI/DS-CDMA chip to enhance the performance via frequency diversity; and combining across chips to eliminate the interfering users on the system. Merging CI/DS-CDMA with the oscillating-beam smart antenna at the base station, we achieve very high capacity via the merger of SDMA (available through directionality of the antenna array and code division multiple access (inherent in CI/DS-CDMA, and very high performance via the construction of receivers that exploit both transmit diversity and frequency diversity. We present the performance gains of the proposed merger.

  17. Central safety factor and β N control on NSTX-U via beam power and plasma boundary shape modification, using TRANSP for closed loop simulations

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, M. D.; Andre, R.; Gates, D. A.; Gerhardt, S.; Goumiri, I. R.; Menard, J.

    2015-04-24

    The high-performance operational goals of NSTX-U will require development of advanced feedback control algorithms, including control of ßN and the safety factor profile. In this work, a novel approach to simultaneously controlling ßN and the value of the safety factor on the magnetic axis, q0, through manipulation of the plasma boundary shape and total beam power, is proposed. Simulations of the proposed scheme show promising results and motivate future experimental implementation and eventual integration into a more complex current profile control scheme planned to include actuation of individual beam powers, density, and loop voltage. As part of this work, a flexible framework for closed loop simulations within the high-fidelity code TRANSP was developed. The framework, used here to identify control-design-oriented models and to tune and test the proposed controller, exploits many of the predictive capabilities of TRANSP and provides a means for performing control calculations based on user-supplied data (controller matrices, target waveforms, etc.). The flexible framework should enable high-fidelity testing of a variety of control algorithms, thereby reducing the amount of expensive experimental time needed to implement new control algorithms on NSTX-U and other devices.

  18. Direct Index Method of Beam Damage Location Detection Based on Difference Theory of Strain Modal Shapes and the Genetic Algorithms Application

    Directory of Open Access Journals (Sweden)

    Bao Zhenming

    2012-01-01

    Full Text Available Structural damage identification is to determine the structure health status and analyze the test results. The three key problems to be solved are as follows: the existence of damage in structure, to detect the damage location, and to confirm the damage degree or damage form. Damage generally changes the structure physical properties (i.e., stiffness, mass, and damping corresponding with the modal characteristics of the structure (i.e., natural frequencies, modal shapes, and modal damping. The research results show that strain mode can be more sensitive and effective for local damage. The direct index method of damage location detection is based on difference theory, without the modal parameter of the original structure. FEM numerical simulation to partial crack with different degree is done. The criteria of damage location detection can be obtained by strain mode difference curve through cubic spline interpolation. Also the genetic algorithm box in Matlab is used. It has been possible to identify the damage to a reasonable level of accuracy.

  19. Beam-scanning system for determination of beam profiles and form factors in merged-beam experiments

    International Nuclear Information System (INIS)

    Keyser, C.J.; Froelich, H.R.; Mitchell, J.B.A.; McGowan, J.W.

    1979-01-01

    A beam-scanning system for a merged electron-ion beam experiment is described. This system is used to determine the horizontal and vertical beam profiles and the form factors at three different locations along the axis of the beams. Design details of the wedge-shaped scanners and the electronic circuit for obtaining beam profiles and form factors are described. The form factor derivation for merged beams is given and an expression in terms of measured quantities is derived. (author)

  20. Laser Beam Focus Analyser

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

    2007-01-01

    the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating......The quantitative and qualitative description of laser beam characteristics is important for process implementation and optimisation. In particular, a need for quantitative characterisation of beam diameter was identified when using fibre lasers for micro manufacturing. Here the beam diameter limits...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...

  1. Beam-beam phenomenology

    International Nuclear Information System (INIS)

    Teng, L.C.

    1980-01-01

    In colliding beam storage rings the beam collision regions are generally so short that the beam-beam interaction can be considered as a series of evenly spaced non-linear kicks superimposed on otherwise stable linear oscillations. Most of the numerical studies on computers were carried out in just this manner. But for some reason this model has not been extensively employed in analytical studies. This is perhaps because all analytical work has so far been done by mathematicians pursuing general transcendental features of non-linear mechanics for whom this specific model of the specific system of colliding beams is too parochial and too repugnantly physical. Be that as it may, this model is of direct interest to accelerator physicists and is amenable to (1) further simplification, (2) physical approximation, and (3) solution by analogy to known phenomena

  2. Ion beam generation and focusing

    International Nuclear Information System (INIS)

    Miller, P.A.; Mendel, C.W.; Swain, D.W.; Goldstein, S.A.

    1975-01-01

    Calculations have shown that efficiently generated and focused ion beams could have significant advantages over electron beams in achieving ignition of inertially-confined thermonuclear fuel. Efficient ion beam generation implies use of a good ion source and suppression of net electron current. Net electron flow can be reduced by allowing electrons to reflex through a highly transparent anode or by use of transverse magnetic fields (either beam self-fields or externally applied fields). Geometric focusing can be achieved if the beam is generated by appropriately shaped electrodes. Experimental results are presented which demonstrate ion beam generation in both reflexing and pinched-flow diodes. Spherically shaped electrodes are used to concentrate a proton beam, and target response to proton deposition is studied

  3. Shape coexistence in krypton and selenium light isotopes studied through Coulomb excitation of radioactive ions beams; Etude de la coexistence de formes dans les isotopes legers du krypton et du selenium par excitation Coulombienne de faisceaux radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Clement, E

    2006-06-15

    The light krypton isotopes show two minima in their potential energy corresponding to elongated (prolate) and compressed (oblate) quadrupole deformation. Both configuration are almost equally bound and occur within an energy range of less than 1 MeV. Such phenomenon is called shape coexistence. An inversion of the ground state deformation from prolate in Kr{sup 78} to oblate in Kr{sup 72} with strong mixing of the configurations in Kr{sup 74} and Kr{sup 76} was proposed based on the systematic of isotopic chain. Coulomb excitation experiments are sensitive to the quadrupole moment. Coulomb excitation experiments of radioactive Kr{sup 74} and Kr{sup 76} beam were performed at GANIL using the SPIRAL facility and the EXOGAM spectrometer. The analysis of these experiments resulted in a complete description of the transition strength and quadrupole moments of the low-lying states. They establish the prolate character of the ground state and an oblate excited state. A complementary lifetime measurement using a 'plunger' device was also performed. Transition strength in neighboring nuclei were measured using the technique of intermediate energy Coulomb excitation at GANIL. The results on the Se{sup 68} nucleus show a sharp change in structure with respects to heavier neighboring nuclei. (author)

  4. Wavelength tuneable laser beam shaping optics

    CSIR Research Space (South Africa)

    Forbes, A

    2006-07-01

    Full Text Available 148.5 149 149.5 150 150.5 151 151.5 152 152.5 E l e m e n t s e p a r a t i o n ( m m ) Refractive Index Element separation 200 250 300 350 400 0.2 0.4 0.6 0.8 1 200 250 300 350 400 0.2 0.4 0.6 0.8 1 What... 350 400 0.2 0.4 0.6 0.8 1 100 150 200 250 300 350 400 0.2 0.4 0.6 0.8 1 Just before 2nd element Just after 2nd element 2 2 0 2 0 1     + = w fM f z pi λ z = f Propagation Effects Page 10 © CSIR 2006...

  5. Compression of Ultrafast Laser Beams

    Science.gov (United States)

    2016-03-01

    Copyright 2003, AIP Publishing LLC. DOI: http://dx.doi.org/10.1063/1.1611998.) When designing the pulse shaper, the laser beam must completely fill the...for the design of future versions of this device. The easiest way to align the pulse shaper is to use the laser beam that will be shaped, without...Afterward, an ultrafast thin beam splitter is placed into the system after the diameter of the laser beam is reduced; this is done to monitor the beam

  6. Electron beams in radiation therapy

    International Nuclear Information System (INIS)

    Bruinvis, I.A.D.

    1987-01-01

    Clinical electron beams in interaction with beam flattening and collimating devices are studied, in order to obtain the means for adequate electron therapy. A treatment planning method for arbitrary field shapes is developed that takes the properties of the collimated electron beams into account. An electron multiple-scattering model is extended to incorporate a model for the loss of electrons with depth, in order to improve electron beam dose planning. A study of ionisation measurements in two different phantom materials yields correction factors for electron beam dosimetry. (Auth.)

  7. Beam in on curing

    International Nuclear Information System (INIS)

    Holl, Dr.

    1981-01-01

    Electron beam curing of paints and allied materials is discussed. Examples of applications are: silicone papers; painting of metal; bonding of flake adhesives; bonding of grinding media (binders); paints for external uses; painting shaped parts; bi-reactive painting systems. An example is given of the calculation of the cost of irradiation. (U.K.)

  8. Coherent beam-beam effects

    International Nuclear Information System (INIS)

    Chao, A.W.

    1992-01-01

    There are two physical pictures that describe the beam-beam interaction in a storage ring collider: The weak-strong and the strong-strong pictures. Both pictures play a role in determining the beam-beam behavior. This review addresses only the strong-strong picture. The corresponding beam dynamical effects are referred to as the coherent beam-beam effects. Some basic knowledge of the weak-strong picture is assumed. To be specific, two beams of opposite charges are considered. (orig.)

  9. Electron beam fusion targets

    International Nuclear Information System (INIS)

    Clauser, M.J.; Sweeney, M.A.

    1975-01-01

    R The behavior of the DT filled gold shells when irradiated by a variety of pulse shapes was studied. In these pulses the power (and beam current) was varied, but the voltage was kept constant at 1 MeV. In general the performance of the target, for a given peak power, was not significantly affected by the pulse shape. Pulses with rise times of up to half the implosion time do not significantly degrade the target performance. The use of the ''optimal pulse'' of laser fusion with a fixed peak power does not appear to improve the performance of these targets. The main function of the ''optimal pulse'' is to produce a large rho r of the target during the thermonuclear burn. In e-beam targets a total rho r of 5--10 g/cm 2 can be obtained without pulse shaping; the problem here is one of achieving high enough temperatures to ignite the DT. (U.S.)

  10. Fire resistance of slim floor beams

    NARCIS (Netherlands)

    Fellinger, J.H.H.; Twilt, L.

    1996-01-01

    Slim floor beams support decks on a wide plate welded on the lower flange of an 1- shaped beam. The air gap between the plate and the lower flange increases the fire resistance of the beam. A Finite Element Method (FEM) model, validated with three fire tests, is used to set up simple calculation

  11. Conical pinched electron beam diode for intense ion beam source

    International Nuclear Information System (INIS)

    Matsukawa, Yoshinobu; Nakagawa, Yoshiro

    1982-01-01

    For the purpose of improvement of the pinched electron beam diode, the production of an ion beam by a diode with electrodes in a conical shape was studied at low voltage operation (--200 kV). The ion beam is emitted from a small region of the diode apex. The mean ion beam current density near the axis at 12 cm from the diode apex is two or three times that from an usual flat parallel diode with the same dimension and impedance. The brightness and the power brightness at the otigin are 450 MA/cm 2 sr and 0.12 TW/cm 2 sr respectively. (author)

  12. Characterization of the Li beam probe with a beam profile monitor on JET.

    Science.gov (United States)

    Nedzelskiy, I S; Korotkov, A; Brix, M; Morgan, P; Vince, J

    2010-10-01

    The lithium beam probe (LBP) is widely used for measurements of the electron density in the edge plasma of magnetically confined fusion experiments. The quality of LBP data strongly depends on the stability and profile shape of the beam. The main beam parameters are as follows: beam energy, beam intensity, beam profile, beam divergence, and the neutralization efficiency. For improved monitoring of the beam parameters, a beam profile monitor (BPM) from the National Electrostatics Corporation (NEC) has been installed in the Li beam line at JET. In the NEC BPM, a single grounded wire formed into a 45° segment of a helix is rotated by a motor about the axis of the helix. During each full revolution, the wire sweeps twice across the beam to give X and Y profiles. In this paper, we will describe the properties of the JET Li beam as measured with the BPM and demonstrate that it facilitates rapid optimization of the gun performance.

  13. Optical vortex beams: Generation, propagation and applications

    Science.gov (United States)

    Cheng, Wen

    An optical vortex (also known as a screw dislocation or phase singularity) is one type of optical singularity that has a spiral phase wave front around a singularity point where the phase is undefined. Optical vortex beams have a lot of applications in areas such as optical communications, LADAR (laser detection and ranging) system, optical tweezers, optical trapping and laser beam shaping. The concepts of optical vortex beams and methods of generation are briefly discussed. The properties of optical vortex beams propagating through atmospheric turbulence have been studied. A numerical modeling is developed and validated which has been applied to study the high order properties of optical vortex beams propagating though a turbulent atmosphere. The simulation results demonstrate the advantage that vectorial vortex beams may be more stable and maintain beam integrity better when they propagate through turbulent atmosphere. As one important application of optical vortex beams, the laser beam shaping is introduced and studied. We propose and demonstrate a method to generate a 2D flat-top beam profile using the second order full Poincare beams. Its applications in two-dimensional flat-top beam shaping with spatially variant polarization under low numerical aperture focusing have been studied both theoretically and experimentally. A novel compact flat-top beam shaper based on the proposed method has been designed, fabricated and tested. Experimental results show that high quality flat-top profile can be obtained with steep edge roll-off. The tolerance to different input beam sizes of the beam shaper is also verified in the experimental demonstration. The proposed and experimentally verified LC beam shaper has the potential to become a promising candidate for compact and low-cost flat-top beam shaping in areas such as laser processing/machining, lithography and medical treatment.

  14. Acquisition and display of beam profilers

    International Nuclear Information System (INIS)

    David, L.; Duneau, P.; Lecorche, E.; Lermine, P.; Vila, J.; Maugeais, C.; Ulrich, M.

    1995-01-01

    The ion beam adjustment requires the knowledge of its shape (its profile). A new electronic interface has been developed for the older multiwire profiles, while an other electronic equipment has been developed for the gas profiles and the microchannel plates. The data from these interfaces are computed to get numerical values and profile shapes, then transmitted by the network to the main control room to be displayed (shapes and data) on every workstation, by different beam tuning programs. (author)

  15. GTK beam test 2017

    CERN Document Server

    Vostinic, Snezana

    2017-01-01

    The GTK is in operation at NA62 since 2014 and is among the few silicon pixel detectors performing 4D tracking. This summer, a beam test was conducted to study the phenomena determining the detector time resolution. The project described here contributed to the beam test preparation, data taking and data analyses. One of the main goals of the test was to understand the weight field contribution to the detector time resolution. This field is distorting the signal pulse shape at the edge of the pixel. Hence, to study this effect, the position of the hits inside the pixel has to be determined. An external telescope was therefore used for this purpose.

  16. Beam loading

    OpenAIRE

    Boussard, Daniel

    1987-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superco...

  17. Molecular beams

    International Nuclear Information System (INIS)

    Pendelbury, J.M.; Smith, K.F.

    1987-01-01

    Studies with directed collision-free beams of particles continue to play an important role in the development of modern physics and chemistry. The deflections suffered by such beams as they pass through electric and magnetic fields or laser radiation provide some of the most direct information about the individual constituents of the beam; the scattering observed when two beams intersect yields important data about the intermolecular forces responsible for the scattering. (author)

  18. Generation of electron Airy beams.

    Science.gov (United States)

    Voloch-Bloch, Noa; Lereah, Yossi; Lilach, Yigal; Gover, Avraham; Arie, Ady

    2013-02-21

    Within the framework of quantum mechanics, a unique particle wave packet exists in the form of the Airy function. Its counterintuitive properties are revealed as it propagates in time or space: the quantum probability wave packet preserves its shape despite dispersion or diffraction and propagates along a parabolic caustic trajectory, even though no force is applied. This does not contradict Newton's laws of motion, because the wave packet centroid propagates along a straight line. Nearly 30 years later, this wave packet, known as an accelerating Airy beam, was realized in the optical domain; later it was generalized to an orthogonal and complete family of beams that propagate along parabolic trajectories, as well as to beams that propagate along arbitrary convex trajectories. Here we report the experimental generation and observation of the Airy beams of free electrons. These electron Airy beams were generated by diffraction of electrons through a nanoscale hologram, which imprinted on the electrons' wavefunction a cubic phase modulation in the transverse plane. The highest-intensity lobes of the generated beams indeed followed parabolic trajectories. We directly observed a non-spreading electron wavefunction that self-heals, restoring its original shape after passing an obstacle. This holographic generation of electron Airy beams opens up new avenues for steering electronic wave packets like their photonic counterparts, because the wave packets can be imprinted with arbitrary shapes or trajectories.

  19. Numerical simulation of electron beam welding with beam oscillations

    Science.gov (United States)

    Trushnikov, D. N.; Permyakov, G. L.

    2017-02-01

    This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.

  20. Beam in on curing

    International Nuclear Information System (INIS)

    Holl, Dr.

    1981-01-01

    This third part of an article on the electron beam curing of paints covers the following aspects: inertising equipment; working without inert gas; increase in temperature when irradiating; irradiating plants; laboratory plants; plant operating from coil to coil; plant for shaped parts; possible applications; decorative films, paper, PVC; packaging material; metallisation of paper films; film bonding; strengthening of flock; coating; pressure sensitive adhesives. (U.K.)

  1. Beam diagnostics

    International Nuclear Information System (INIS)

    Bogaty, J.; Clifft, B.E.; Zinkann, G.P.; Pardo, R.C.

    1995-01-01

    The ECR-PII injector beam line is operated at a fixed ion velocity. The platform high voltage is chosen so that all ions have a velocity of 0.0085c at the PII entrance. If a previous tune configuration for the linac is to be used, the beam arrival time must be matched to the previous tune as well. A nondestructive beam-phase pickup detector was developed and installed at the entrance to the PII linac. This device provides continuous phase and beam current information and allows quick optimization of the beam injected into PII. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum interface where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam-induced radiofrequency signals are summed against an offset frequency generated by our master oscillator. The resulting kilohertz difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop which stabilizes phase readings if beam is unstable. The other channel uses a linear full wave active rectifier circuit which converts kilohertz sine wave signal amplitude to a D.C. voltage representing beam current. A prototype set of electronics is now in use with the detector and we began to use the system in operation to set the arrival beam phase. A permanent version of the electronics system for the phase detector is now under construction. Additional nondestructive beam intensity and phase monitors at the open-quotes Boosterclose quotes and open-quotes ATLASclose quotes linac sections are planned as well as on some of the high-energy beam lines. Such a monitor will be particularly useful for FMA experiments where the primary beam hits one of the electric deflector plates

  2. On the validity of localized approximations for Bessel beams: All N-Bessel beams are identically equal to zero

    International Nuclear Information System (INIS)

    Gouesbet, Gérard

    2016-01-01

    Localized approximation procedures are efficient ways to evaluate beam shape coefficients of a laser beam. They are particularly useful when other methods are ineffective or inefficient. Several papers in the literature have reported the use of such procedures to evaluate the beam shape coefficients of Bessel beams. Relying on the concept of N-beams, it is demonstrated that care must be taken when constructing a localized approximation for a Bessel beam, namely a localized Bessel beam is satisfactorily close enough to the intended beam only when the axicon angle is small enough. - Highlights: • Localized approximation has been used to evaluate BSCs of Bessel beams. • N-beam procedure fails to provide a localized approximation for Bessel beams. • Localized approximation should be used only for small axicon angles.

  3. Designing H-shaped micromechanical filters

    International Nuclear Information System (INIS)

    Arhaug, O P; Soeraasen, O

    2006-01-01

    This paper investigates the design constraints and possibilities given when designing a micromechanical band pass filter for intermediate frequencies (e.g. 10 MHz). The class of filters are based on coupled clamped-clamped beams constituting an H-shaped structure. A primary beam can electrostatically be activated in one of its different harmonic modes, setting the filter center frequency. The motion is transferred to an accompanying beam of equal dimensions by a mechanical coupling beam. The placement or coupling points of the quarterwavelength coupling beam which connects the vertically resonating beams is critical with respect to the bandwidth of the filters. Of special concern has been to investigate realistic dimensions allowing the filters to be processed by an actual foundry process and to find out how the choice of materials and actual dimensions would affect the performance

  4. Single lens laser beam shaper

    Science.gov (United States)

    Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

    2011-10-04

    A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

  5. Initial results from beam commissioning of the LHC beam dump system

    CERN Document Server

    Goddard, B; Carlier, E; Ducimetière, L; Gallet, E; Gyr, M; Jensen, L; Jones, R; Kain, V; Kramer, T; Lamont, M; Meddahi, M; Mertens, V; Risselada, Thys; Uythoven, J; Wenninger, J; Weterings, W

    2010-01-01

    Initial commissioning of the LHC beam dump system with beam took place in August and September 2008. The preparation, setting-up and the tests performed are described together with results of the extractions of beam into the dump lines. Analysis of the first detailed aperture measurements of the extraction channels and kicker performance derived from dilution sweep shapes are presented. The performance of the other equipment subsystems is summarised, in particular that of the dedicated dump system beam instrumentation.

  6. Beam loading

    CERN Document Server

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.

  7. Beam loading

    International Nuclear Information System (INIS)

    Gamp, Alexander

    2013-01-01

    We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed. (author)

  8. Lightweight HPC beam OMEGA

    Science.gov (United States)

    Sýkora, Michal; Jedlinský, Petr; Komanec, Jan

    2017-09-01

    In the design and construction of precast bridge structures, a general goal is to achieve the maximum possible span length. Often, the weight of individual beams makes them difficult to handle, which may be a limiting factor in achieving the desired span. The design of the OMEGA beam aims to solve a part of these problems. It is a thin-walled shell made of prestressed high-performance concrete (HPC) in the shape of inverted Ω character. The concrete shell with prestressed strands is fitted with a non-stressed tendon already in the casting yard and is more easily transported and installed on the site. The shells are subsequently completed with mild steel reinforcement and cores are cast in situ together with the deck. The OMEGA beams can also be used as an alternative to steel - concrete composite bridges. Due to the higher production complexity, OMEGA beam can hardly substitute conventional prestressed beams like T or PETRA completely, but it can be a useful alternative for specific construction needs.

  9. Design of HELIOS beam diagnostics

    International Nuclear Information System (INIS)

    Seagrave, J.D.; Bigio, I.J.; Jackson, S.V.; Laird, A.M.

    1979-01-01

    Verification of satisfactory operation of the HELIOS eight-beam laser system requires measurement of many parameters of each beam on each shot. Fifty-joule samples of each of the eight 1250-J, subnanosecond 34-cm-diameter beams of the HELIOS system are diverted to a gallery of eight folded telescopes and beamsplit to provide diagnostic measurements. Total pulse energy, and prepulse and postlase energy of each beam are measured; pulse shape details and a wavelength spectrum of a selected beam from each shot are measured; and provision is made for retropulse measurement and optical quality monitoring. All data are recorded digitally in a local screen room, with control and communication through a fiberoptic link to the main HELIOS computer

  10. Applications of electron lenses: scraping of high-power beams, beam-beam compensation, and nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio

    2014-09-11

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Hollow electron beam collimation and halo control were studied as an option to complement the collimation system for the upgrades of the Large Hadron Collider (LHC) at CERN; a conceptual design was recently completed. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles. At Fermilab, we are planning to install an electron lens in the Integrable Optics Test Accelerator (IOTA, a 40-m ring for 150-MeV electrons) as one of the proof-of-principle implementations of nonlinear integrable optics to achieve large tune spreads and more stable beams without loss of dynamic aperture.

  11. Superresolution beams

    CSIR Research Space (South Africa)

    Ngcobo, S

    2011-11-01

    Full Text Available The transformation of a Gaussian beam (GB) into a symmetrical higher order TEMp0 Laguerre Gaussian beam (LGB) intensity distribution of which is further rectified and transformed into a Gaussian intensity distribution in the plane of a converging...

  12. Linear shaped charge

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, David; Stofleth, Jerome H.; Saul, Venner W.

    2017-07-11

    Linear shaped charges are described herein. In a general embodiment, the linear shaped charge has an explosive with an elongated arrowhead-shaped profile. The linear shaped charge also has and an elongated v-shaped liner that is inset into a recess of the explosive. Another linear shaped charge includes an explosive that is shaped as a star-shaped prism. Liners are inset into crevices of the explosive, where the explosive acts as a tamper.

  13. Computerized tomographic scanner with shaped radiation filter

    International Nuclear Information System (INIS)

    Carlson, R.W.; Walters, R.G.

    1981-01-01

    The invention comprises a shaped filter and a filter correction circuitry for computerized tomographic scanners. The shaped filter is a generally u-shaped block of filter material which is adapted to be mounted between the source of radiation and the scan circle. The u-shaped block has a parabolic recess. The filter material may be beryllium, aluminum, sulphur, calcium, titanium, erbium, copper, and compounds including oxides and alloys thereof. The filter correction circuit comprises a first filter correction profile adding circuit for adding a first scaler valve to each intensity valve in a data line. The data line is operated on by a beam hardness correction polynomial. After the beam hardness polynomial correction operation, a second filter correction circuit adds a second filter correction profile consisting of a table of scalor values, one corresponding to each intensity reading in the data line

  14. Beam limiter for thermonuclear fusion devices

    International Nuclear Information System (INIS)

    Kaminsky, M.S.

    1977-01-01

    The invention pertains to a beam limiter to prevent collisions between a plasma and the inner surface of a hollow body in which the plasma is confined. The patent claims pertain to suitable geometrical shapes of the beam limiter. (GG) [de

  15. Coherent beam-beam effect

    International Nuclear Information System (INIS)

    Chao, A.W.; Keil, E.

    1979-06-01

    The stability of the coherent beam-beam effect between rigid bunches is studied analytically and numerically for a linear force by evaluating eigenvalues. For a realistic force, the stability is investigated by following the bunches for many revolutions. 4 refs., 13 figs., 2 tabs

  16. Beam properties and stability of a flattening-filter free 7 MV beam--An overview

    International Nuclear Information System (INIS)

    Dzierma, Yvonne; Licht, Norbert; Nuesken, Frank; Ruebe, Christian

    2012-01-01

    Purpose: Several works have recently focused on flattening-filter-free (FFF) beams of linear accelerators of various companies (in particular, Varian and Elekta), but no overview as yet exists for the flattening-filter free 7XU beam (Siemens Artiste). Methods: Dosimetric properties of the 7XU beam were measured in May and September 2011. We present depth dose curves and beam profiles, output factors, and MLC transmission and assess the stability of the measurements. The 7XU beam was commissioned in the Pinnacle³ treatment planning system (TPS), and modeling results including the spectrum are presented. Results: The percent depth dose curve of the 7XU beam is similar to the flat 6X beam line, with a slightly smaller surface dose. The beam profiles show the characteristic shape of flattening-filter free beams, with deviations between measurements of generally less than 1%. The output factors of the 7XU beam decrease more slowly than for the 6X beam. The MLC transmission is comparable but slightly less for the 7XU beam. The 7XU beam can be adequately modeled by the Pinnacle³ TPS, with successful dosimetric verification. The spectrum of the 7XU beam has lower photon fluence up to approximately 2.5 MeV and higher fluence beyond, with a slightly higher mean energy. Conclusions: The 7XU beam has been commissioned for clinical use after successful modeling, stability checks, and dosimetric verification.

  17. Silicon microfabricated beam expander

    International Nuclear Information System (INIS)

    Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

    2015-01-01

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed

  18. Silicon microfabricated beam expander

    Science.gov (United States)

    Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

    2015-03-01

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

  19. Silicon microfabricated beam expander

    Energy Technology Data Exchange (ETDEWEB)

    Othman, A., E-mail: aliman@ppinang.uitm.edu.my; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A. [Faculty of Electrical Engineering, Universiti Teknologi MARA Malaysia, 40450, Shah Alam, Selangor (Malaysia); Ain, M. F. [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300,Nibong Tebal, Pulau Pinang (Malaysia)

    2015-03-30

    The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

  20. Production of ion beam by conical pinched electron beam diode

    International Nuclear Information System (INIS)

    Matsukawa, Y.; Nakagawa, Y.

    1982-01-01

    Some properties of the ion beam produced by pinched electron beam diode having conical shape electrodes and organic insulator anode was studied. Ion energy is about 200keV and the peak diode current is about 30 kA. At 11cm from the diode apex, not the geometrical focus point, concentrated ion beam was obtained. Its density is more than 500A/cm 2 . The mean ion current density within the radius of 1.6cm around the axis from conical diode is two or three times that from an usual pinched electron beam diode with flat parallel electrodes of same dimension and impedance under the same conditions. (author)

  1. A map for the thick beam-beam interaction

    International Nuclear Information System (INIS)

    Irwin, J.; Chen, T.

    1995-01-01

    The authors give a closed-form expression for the thick beam-beam interaction for a small disruption parameter, as typical in electron-positron storage rings. The dependence on transverse angle and position of the particle trajectory as well as the longitudinal position of collision and the waist-modified shape of the beam distribution are included. Large incident angles, as are present for beam-halo particles or for large crossing-angle geometry, are accurately represented. The closed-form expression is well approximated by polynomials times the complex error function. Comparisons with multi-slice representations show even the first order terms are more accurate than a five slice representation, saving a factor of 5 in computation time

  2. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    Considerable experience has now been gained with the various beam transport lines, and a number of minor changes have been made to improve the ease of operation. These include: replacement of certain little-used slits by profile monitors (harps or scanners); relocation of steering magnets, closer to diagnostic harps or profile scanners; installation of a scanner inside the isocentric neutron therapy system; and conversion of a 2-doublet quadrupole telescope (on the neutron therapy beamline) to a 2-triplet telescope. The beam-swinger project has been delayed by very late delivery of the magnet iron to the manufacturer, but is now progressing smoothly. The K=600 spectrometer magnets have now been delivered and are being assembled for field mapping. The x,y-table with its associated mapping equipment is complete, together with the driver software. One of the experimental areas has been dedicated to the production of collimated neutron beams and has been equipped with a bending magnet and beam dump, together with steel collimators fixed at 4 degrees intervals from 0 degrees to 16 degrees. Changes to the target cooling and shielding system for isotope production have led to a request for much smaller beam spot sizes on target, and preparations have been made for rearrangement of the isotope beamline to permit installation of quadrupole triplets on the three beamlines after the switching magnet. A practical system of quadrupoles for matching beam properties to the spectrometer has been designed. 6 figs

  3. A pencil beam algorithm for helium ion beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Hermann; Stroebele, Julia; Schreiner, Thomas; Hirtl, Albert; Georg, Dietmar [Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria); PEG MedAustron, 2700 Wiener Neustadt (Austria); Department of Nuclear Medicine, Medical University of Vienna, 1090 Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, 1090 Vienna (Austria); Department of Radiation Oncology, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria) and Comprehensive Cancer Center, Medical University of Vienna/AKH Vienna, 1090 Vienna (Austria)

    2012-11-15

    Purpose: To develop a flexible pencil beam algorithm for helium ion beam therapy. Dose distributions were calculated using the newly developed pencil beam algorithm and validated using Monte Carlo (MC) methods. Methods: The algorithm was based on the established theory of fluence weighted elemental pencil beam (PB) kernels. Using a new real-time splitting approach, a minimization routine selects the optimal shape for each sub-beam. Dose depositions along the beam path were determined using a look-up table (LUT). Data for LUT generation were derived from MC simulations in water using GATE 6.1. For materials other than water, dose depositions were calculated by the algorithm using water-equivalent depth scaling. Lateral beam spreading caused by multiple scattering has been accounted for by implementing a non-local scattering formula developed by Gottschalk. A new nuclear correction was modelled using a Voigt function and implemented by a LUT approach. Validation simulations have been performed using a phantom filled with homogeneous materials or heterogeneous slabs of up to 3 cm. The beams were incident perpendicular to the phantoms surface with initial particle energies ranging from 50 to 250 MeV/A with a total number of 10{sup 7} ions per beam. For comparison a special evaluation software was developed calculating the gamma indices for dose distributions. Results: In homogeneous phantoms, maximum range deviations between PB and MC of less than 1.1% and differences in the width of the distal energy falloff of the Bragg-Peak from 80% to 20% of less than 0.1 mm were found. Heterogeneous phantoms using layered slabs satisfied a {gamma}-index criterion of 2%/2mm of the local value except for some single voxels. For more complex phantoms using laterally arranged bone-air slabs, the {gamma}-index criterion was exceeded in some areas giving a maximum {gamma}-index of 1.75 and 4.9% of the voxels showed {gamma}-index values larger than one. The calculation precision of the

  4. AN INVESTIGATION OF THE BEAM MONITOR FOR THE CLUSTER KLYSTRON

    International Nuclear Information System (INIS)

    ZHAO, Y.

    2001-01-01

    The cluster klystron project required a beam monitor to check the quality of the hollow beam shape. Since the power density of the beam is very large, a common phosphorescent screen doesn't work. We investigated varies types of monitors. The related problems were also discussed

  5. Beam tomography in two and four dimensions

    International Nuclear Information System (INIS)

    Sander, O.R.; Minerbo, G.N.; Jameson, R.A.; Chamberlin, D.D.

    1979-01-01

    The coming generations of high beam-power accelerators require new techniques to monitor the emittance and the shape of the beam; in particular, measurements that do not interfere with the beam itself are necessary. A new computational algorithm, MENT (Maximum ENTropy), will be presented that combines nondestructive profile measurements taken from a number of stations along the beam line with beam-dynamics calculations to compute a four-dimensional phase-space distribution. A version of MENT has been used on experimental data to reconstruct the two-dimensional transverse emittance of the Clinton P. Anderson Meson Physics Facility (LAMPF) proton beam at 100 MeV and the H - beam at 750 keV. Wire scanners at three stations were used to get the one-dimensional profiles. Results will be compared with those gained using the destructive slit and collector method and with those gained using MART (Multiplicative Algebraic Reconstruction Technique) on the same three profiles

  6. Beam Splitter for Spin Waves in Quantum Spin Network

    OpenAIRE

    Yang, S.; Song, Z.; Sun, C. P.

    2005-01-01

    We theoretically design and analytically study a controllable beam splitter for the spin wave propagating in a star-shaped (e.g., a $Y$-shaped beam) spin network. Such a solid state beam splitter can display quantum interference and quantum entanglement by the well-aimed controls of interaction on nodes. It will enable an elementary interferometric device for scalable quantum information processing based on the solid system.

  7. Additive Manufacturing of Shape Memory Alloys

    Science.gov (United States)

    Van Humbeeck, Jan

    2018-04-01

    Selective Laser Melting (SLM) is an additive manufacturing production process, also called 3D printing, in which functional, complex parts are produced by selectively melting patterns in consecutive layers of powder with a laser beam. The pattern the laser beam is following is controlled by software that calculates the pattern by slicing a 3D CAD model of the part to be constructed. Apart from SLM, also other additive manufacturing techniques such as EBM (Electron Beam Melting), FDM (Fused Deposition Modelling), WAAM (Wire Arc Additive Manufacturing), LENS (Laser Engineered Net Shaping such as Laser Cladding) and binder jetting allow to construct complete parts layer upon layer. But since more experience of AM of shape memory alloys is collected by SLM, this paper will overview the potentials, limits and problems of producing NiTi parts by SLM.

  8. Beam structure and transverse emittance studies of high-energy ion beams

    International Nuclear Information System (INIS)

    Saadatmand, K.; Johnson, K.F.; Schneider, J.D.

    1991-01-01

    A visual diagnostic technique has been developed to monitor and study ion beam structure shape and size along a transport line. In this technique, a commercially available fluorescent screen is utilized in conjunction with a video camera. This visual representation of the beam structure is digitized and enhanced through use of false-color coding and displayed on a TV monitor for on-line viewing. Digitized information is stored for further off-line processing (e.g., extraction of beam profiles). An optional wire grid placed upstream of the fluor screen adds the capability of transverse emittance (or angular spread) measurement to this technique. This diagnostic allows real-time observation of the beam response to parameter changes (e.g., evolution of the beam structure, shifts in the beam intensity at various spatial locations within the beam perimeter, and shifts in the beam center and position). 3 refs., 5 figs

  9. Quantum beams

    International Nuclear Information System (INIS)

    Uesaka, Mitsuru

    2003-01-01

    Present state and future prospect are described on quantum beams for medical use. Efforts for compactness of linac for advanced cancer therapy have brought about the production of machines like Accuray's CyberKnife and TOMOTHERAPY (Tomo Therapy Inc.) where the acceleration frequency of X-band (9-11 GHz) is used. For cervical vein angiography by the X-band linac, a compact hard X-ray source is developed which is based on the (reverse) Compton scattering through laser-electron collision. More intense beam and laser are necessary at present. A compact machine generating the particle beam of 10 MeV-1 GeV (laser-plasma accelerator) for cancer therapy is also developed using the recent compression technique (chirped-pulse amplification) to generate laser of >10 TW. Tokyo University is studying for the electron beam with energy of GeV order, for the laser-based synchrotron X-ray, and for imaging by the short pulse ion beam. Development of advanced compact accelerators is globally attempted. In Japan, a virtual laboratory by National Institute of Radiological Sciences (NIRS), a working group of universities and research facilities through the Ministry of Education, Culture, Sports, Science and Technology, started in 2001 for practical manufacturing of the above-mentioned machines for cancer therapy and for angiography. Virtual Factory (Inc.), a business venture, is to be stood in future. (N.I.)

  10. Characterization and monitoring of transverse beam tails

    International Nuclear Information System (INIS)

    Seeman, J.T.; Decker, F.J.; Hsu, I.; Young, C.

    1991-05-01

    Low emittance electron beams accelerated to high energy in a linac experience transverse effects (wakefield, filamentation, optics) which produce non-Gaussian projected transverse beam distributions. Characterizations of the beam shapes are difficult because the shapes are asymmetric and change with betatron phase. In this note several methods to describe beam distributions are discussed including an accelerator physics model of these tails. The uses of these characterizations in monitoring the beam emittances in the SLC are described in this paper. First, two dimensional distributions from profile monitor screens are reviewed showing correlated tails. Second, a fitting technique for non-Gaussian one dimensional distributions is used to extract the core from the tail areas. Finally, a model for tail propagation in the linac is given. 3 refs., 6 figs

  11. Electron beam spectrum monitor using synchrotron light

    International Nuclear Information System (INIS)

    Reagan, D.; Hostetler, T.E.

    1979-03-01

    This instrument shows the positions, widths, and shapes of momentum spectra of SLAC beams. It uses synchrotron light produced when the beam is deflected by a magnet. Some of the light is focused on the face of an image splitter consisting of acrylic light pipes. The light pipes illuminate twelve photomultiplier tubes. Pulses from the PM tubes are integrated, multiplexed, and displayed on an oscilloscope. The resolution of the instrument is usually better than 0.2%. It has some advantages over the secondary emitter foil spectrum monitors (SEM's) currently in use at SLAC. It need never be put out of service to avoid disturbing the beam. It is as sensitive as the most sensitive SLAC SEM. (Its performance has been optimized for high-current beams; it can easily be made much more sensitive.) It provides information on a pulse-to-pulse basis and, with better cables, could indicate electron beam pulse shapes

  12. Importance of beam-beam tune spread to collective beam-beam instability in hadron colliders

    International Nuclear Information System (INIS)

    Jin Lihui; Shi Jicong

    2004-01-01

    In hadron colliders, electron-beam compensation of beam-beam tune spread has been explored for a reduction of beam-beam effects. In this paper, effects of the tune-spread compensation on beam-beam instabilities were studied with a self-consistent beam-beam simulation in model lattices of Tevatron and Large Hodron Collider. It was found that the reduction of the tune spread with the electron-beam compensation could induce a coherent beam-beam instability. The merit of the compensation with different degrees of tune-spread reduction was evaluated based on beam-size growth. When two beams have a same betatron tune, the compensation could do more harm than good to the beams when only beam-beam effects are considered. If a tune split between two beams is large enough, the compensation with a small reduction of the tune spread could benefit beams as Landau damping suppresses the coherent beam-beam instability. The result indicates that nonlinear (nonintegrable) beam-beam effects could dominate beam dynamics and a reduction of beam-beam tune spread by introducing additional beam-beam interactions and reducing Landau damping may not improve the stability of beams

  13. Beam dynamics

    International Nuclear Information System (INIS)

    Abell, D; Adelmann, A; Amundson, J; Dragt, A; Mottershead, C; Neri, F; Pogorelov, I; Qiang, J; Ryne, R; Shalf, J; Siegerist, C; Spentzouris, P; Stern, E; Venturini, M; Walstrom, P

    2006-01-01

    We describe some of the accomplishments of the Beam Dynamics portion of the SciDAC Accelerator Science and Technology project. During the course of the project, our beam dynamics software has evolved from the era of different codes for each physical effect to the era of hybrid codes combining start-of-the-art implementations for multiple physical effects to the beginning of the era of true multi-physics frameworks. We describe some of the infrastructure that has been developed over the course of the project and advanced features of the most recent developments, the interplay betwen beam studies and simulations and applications to current machines at Fermilab. Finally we discuss current and future plans for simulations of the International Linear Collider

  14. Beam-Forming Concentrating Solar Thermal Array Power Systems

    Science.gov (United States)

    Cwik, Thomas A. (Inventor); Dimotakis, Paul E. (Inventor); Hoppe, Daniel J. (Inventor)

    2016-01-01

    The present invention relates to concentrating solar-power systems and, more particularly, beam-forming concentrating solar thermal array power systems. A solar thermal array power system is provided, including a plurality of solar concentrators arranged in pods. Each solar concentrator includes a solar collector, one or more beam-forming elements, and one or more beam-steering elements. The solar collector is dimensioned to collect and divert incoming rays of sunlight. The beam-forming elements intercept the diverted rays of sunlight, and are shaped to concentrate the rays of sunlight into a beam. The steering elements are shaped, dimensioned, positioned, and/or oriented to deflect the beam toward a beam output path. The beams from the concentrators are converted to heat at a receiver, and the heat may be temporarily stored or directly used to generate electricity.

  15. Reinforced Airfoil Shaped Body

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to an airfoil shaped body with a leading edge and a trailing edge extending along the longitudinal extension of the body and defining a profile chord, the airfoil shaped body comprising an airfoil shaped facing that forms the outer surface of the airfoil shaped body...

  16. Shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Bearinger, Jane P.

    2017-08-29

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  17. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  18. Optical tractor Bessel polarized beams

    Science.gov (United States)

    Mitri, F. G.; Li, R. X.; Guo, L. X.; Ding, C. Y.

    2017-01-01

    Axial and transverse radiation force cross-sections of optical tractor Bessel polarized beams are theoretically investigated for a dielectric sphere with particular emphasis on the beam topological charge (or order), half-cone angle and polarization. The angular spectrum decomposition method (ASDM) is used to derive the non-paraxial electromagnetic (EM) field components of the Bessel beams. The multipole expansion method using vector spherical harmonics is utilized and appropriate beam-shape coefficients are derived in order to compute the radiation force cross-sections. The analysis has no limitation to a particular range of frequencies such that the Rayleigh, Mie or geometrical optics regimes can all be considered effectively using the present rigorous formalism. The focus of this investigation is to identify some of the tractor beam conditions so as to achieve retrograde motion of a dielectric sphere located arbitrarily in space. Numerical computations for the axial and transverse radiation force cross-sections are presented for linear, right-circular, radial, azimuthal and mixed polarizations of the individual plane waves forming the Bessel beams of zeroth- and first-order (with positive or negative helicity), respectively. As the sphere shifts off the beam's axis, the axial pulling (tractor) force is weakened. Moreover, the transverse radiation force cross-section field changes with the sphere's size factor ka (where k is the wavenumber and a is the sphere radius). Both stable and unstable equilibrium regions around the beam's axis are found, depending on the choice of ka and the half-cone angle α0. These results are particularly important in the development of emergent technologies for the photophoretic assembly of optically-engineered (meta)materials with designed properties using optical tractor (vortex) beams, particle manipulation, levitation and positioning, and other applications.

  19. Monitoring external beam radiotherapy using real-time beam visualization

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Cesare H. [Department of Mechanical Engineering and Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Naczynski, Dominik J.; Yu, Shu-Jung S.; Xing, Lei, E-mail: lei@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305 (United States)

    2015-01-15

    Purpose: To characterize the performance of a novel radiation therapy monitoring technique that utilizes a flexible scintillating film, common optical detectors, and image processing algorithms for real-time beam visualization (RT-BV). Methods: Scintillating films were formed by mixing Gd{sub 2}O{sub 2}S:Tb (GOS) with silicone and casting the mixture at room temperature. The films were placed in the path of therapeutic beams generated by medical linear accelerators (LINAC). The emitted light was subsequently captured using a CMOS digital camera. Image processing algorithms were used to extract the intensity, shape, and location of the radiation field at various beam energies, dose rates, and collimator locations. The measurement results were compared with known collimator settings to validate the performance of the imaging system. Results: The RT-BV system achieved a sufficient contrast-to-noise ratio to enable real-time monitoring of the LINAC beam at 20 fps with normal ambient lighting in the LINAC room. The RT-BV system successfully identified collimator movements with sub-millimeter resolution. Conclusions: The RT-BV system is capable of localizing radiation therapy beams with sub-millimeter precision and tracking beam movement at video-rate exposure.

  20. Apparatus for irradiation with electron beam

    International Nuclear Information System (INIS)

    Uehara, K.; Ito, A.; Nishimune, K.; Fujita, K.

    1976-01-01

    An irradiation apparatus with high energy electrons is disclosed in which a wire shaped or linear object to be irradiated is moved back and forth many times under an electron window so as to irradiate it with an electron beam. According to one feature of the invention, an electron beam, which leaks through gaps between the objects to be irradiated or which penetrates the objects to be irradiated, is reversed by a magnetic field approximately perpendicular to the scanning face of the electron beam by means of a magnet which is disposed under the objects to be irradiated, and the reversed electron beam is thereby again applied to the objects to be irradiated. A high utilization rate of the electron beam is accomplished, and the objects can be thereby uniformly irradiated with the electron beam. 4 claims, 6 drawing figures

  1. Self-reconstruction of diffraction-free and accelerating laser beams in scattering media

    International Nuclear Information System (INIS)

    Ersoy, T.; Yalizay, B.; Akturk, S.

    2012-01-01

    We experimentally investigate propagation of laser beams with different intensity profiles in highly scattering media. We generate transverse laser amplitude profiles with Gaussian, Bessel and Airy function envelopes. We then propagate these beams through optical phantoms formed with variable density intralipid solutions. At the sample exit, we compare change in maximum intensities, as well as beam profile reconstruction. We show that self-reconstruction properties of Bessel and Airy beams bring about slower decrease in maximum intensity with increasing scatterer density. On the other hand, the beam profiles deteriorate faster, as compared to reference Gaussian beams. Slower decrease in the intensity can be attributed to the wavevector spectra providing a continuous flow of energy to the beam center, while beam deterioration is linked to total beam volume in the scattering medium. These results show that beam shaping methods can significantly enhance delivery of intense light deeper into turbid media, but this enhancement is compromised by stronger speckling of beam profiles. -- Highlights: ► We experimentally investigate propagation of shaped laser beams in turbid media. ► Peak intensity of Bessel and Airy beams decrease slower with increasing scatterer. ► Shaped beam profiles deteriorate faster, as compared to reference Gaussian beams. ► Shaped beam profiles can enhance applications of lasers inscattering media.

  2. Asymmetric Shaped-Pattern Synthesis for Planar Antenna Arrays

    Directory of Open Access Journals (Sweden)

    T. M. Bruintjes

    2016-01-01

    Full Text Available A procedure to synthesize asymmetrically shaped beam patterns is developed for planar antenna arrays. As it is based on the quasi-analytical method of collapsed distributions, the main advantage of this procedure is the ability to realize a shaped (null-free region with very low ripple. Smooth and asymmetrically shaped regions can be used for Direction-of-Arrival estimation and subsequently for efficient tracking with a single output (fully analog beamformer.

  3. Gyrator transform of Gaussian beams with phase difference and generation of hollow beam

    Science.gov (United States)

    Xiao, Zhiyu; Xia, Hui; Yu, Tao; Xie, Ding; Xie, Wenke

    2018-03-01

    The optical expression of Gaussian beams with phase difference, which is caused by gyrator transform (GT), has been obtained. The intensity and phase distribution of transform Gaussian beams are analyzed. It is found that the circular hollow vortex beam can be obtained by overlapping two GT Gaussian beams with π phase difference. The effect of parameters on the intensity and phase distributions of the hollow vortex beam are discussed. The results show that the shape of intensity distribution is significantly influenced by GT angle α and propagation distance z. The size of the hollow vortex beam can be adjusted by waist width ω 0. Compared with previously reported results, the work shows that the hollow vortex beam can be obtained without any model conversion of the light source.

  4. Study of oblate nuclear shapes and shape coexistence in neutron-deficient rare earth isotopes

    CERN Multimedia

    Guttormsen, M S; Reiter, P; Larsen, A; Korten, W; Clement, E; Siem, S; Renstrom, T; Buerger, A; Jenkins, D G

    We propose to investigate nuclear shapes and shape coexistence in neutron-deficient rare earth nuclei below the N=82 shell closure at the ISOLDE facility by employing Coulomb excitation of Nd, Sm, Gd, and Dy beams from the REX accelerator and the Miniball experiment. Nuclear shapes are expected to change rapidly in this region of the nuclear chart. The measurement of electric quadrupole moments of excited states and the transition rates between them serves as a stringent test of theoretical models and effective nucleon-nucleon interactions.

  5. Beam transport

    International Nuclear Information System (INIS)

    1988-01-01

    The beam diagnostic components for both the transfer and the high-energy beamlines perform well except for some of the scanners whose noise pick-up has become a problem, especially at low beam intensities. This noise pick-up is primarily due to deterioration of the bearings in the scanner. At some locations in the high-energy beamlines, scanners were replaced by harps as the scanners proved to be practically useless for the low-intensity beams required in the experimental areas. The slits in the low-energy beamline, which are not water-cooled, have to be repaired at regular intervals because of vacuum leaks. Overheating causes the ceramic feedthroughs to deteriorate resulting in the vacuum leaks. Water-cooled slits have been ordered to replace the existing slits which will later be used in the beamlines associated with the second injector cyclotron SPC2. The current-measurement system will be slightly modified and should then be much more reliable. 3 figs

  6. Systems and methods of varying charged particle beam spot size

    Science.gov (United States)

    Chen, Yu-Jiuan

    2014-09-02

    Methods and devices enable shaping of a charged particle beam. A modified dielectric wall accelerator includes a high gradient lens section and a main section. The high gradient lens section can be dynamically adjusted to establish the desired electric fields to minimize undesirable transverse defocusing fields at the entrance to the dielectric wall accelerator. Once a baseline setting with desirable output beam characteristic is established, the output beam can be dynamically modified to vary the output beam characteristics. The output beam can be modified by slightly adjusting the electric fields established across different sections of the modified dielectric wall accelerator. Additional control over the shape of the output beam can be excreted by introducing intentional timing de-synchronization offsets and producing an injected beam that is not fully matched to the entrance of the modified dielectric accelerator.

  7. Synchronous characterization of semiconductor microcavity laser beam.

    Science.gov (United States)

    Wang, T; Lippi, G L

    2015-06-01

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

  8. High power neutral beam injection in LHD

    International Nuclear Information System (INIS)

    Tsumori, K.; Takeiri, Y.; Nagaoka, K.

    2005-01-01

    The results of high power injection with a neutral beam injection (NBI) system for the large helical device (LHD) are reported. The system consists of three beam-lines, and two hydrogen negative ion (H - ion) sources are installed in each beam-line. In order to improve the injection power, the new beam accelerator with multi-slot grounded grid (MSGG) has been developed and applied to one of the beam-lines. Using the accelerator, the maximum powers of 5.7 MW were achieved in 2003 and 2004, and the energy of 189 keV reached at maximum. The power and energy exceeded the design values of the individual beam-line for LHD. The other beam-lines also increased their injection power up to about 4 MW, and the total injection power of 13.1 MW was achieved with three beam-lines in 2003. Although the accelerator had an advantage in high power beam injection, it involved a demerit in the beam focal condition. The disadvantage was resolved by modifying the aperture shapes of the steering grid. (author)

  9. On the validity of localized approximation for an on-axis zeroth-order Bessel beam

    International Nuclear Information System (INIS)

    Gouesbet, Gérard; Lock, J.A.; Ambrosio, L.A.; Wang, J.J.

    2017-01-01

    Localized approximation procedures are efficient ways to evaluate beam shape coefficients of laser beams, and are particularly useful when other methods are ineffective or inefficient. Several papers in the literature have reported the use of such procedures to evaluate the beam shape coefficients of Bessel beams. Examining the specific case of an on-axis zeroth-order Bessel beam, we demonstrate that localized approximation procedures are valid only for small axicon angles. - Highlights: • The localized approximation has been widely used to evaluate the Beam Shape Coefficients (BSCs) of Bessel beams. • The validity of this approximation is examined in the case of an on-axis zeroth-order Bessel beam. • It is demonstrated, in this specific example, that the localized approximation is efficient only for small enough axicon angles. • It is easily argued that this result must remain true for any kind of Bessel beams.

  10. Robust modal curvature features for identifying multiple damage in beams

    Science.gov (United States)

    Ostachowicz, Wiesław; Xu, Wei; Bai, Runbo; Radzieński, Maciej; Cao, Maosen

    2014-03-01

    Curvature mode shape is an effective feature for damage detection in beams. However, it is susceptible to measurement noise, easily impairing its advantage of sensitivity to damage. To deal with this deficiency, this study formulates an improved curvature mode shape for multiple damage detection in beams based on integrating a wavelet transform (WT) and a Teager energy operator (TEO). The improved curvature mode shape, termed the WT - TEO curvature mode shape, has inherent capabilities of immunity to noise and sensitivity to damage. The proposed method is experimentally validated by identifying multiple cracks in cantilever steel beams with the mode shapes acquired using a scanning laser vibrometer. The results demonstrate that the improved curvature mode shape can identify multiple damage accurately and reliably, and it is fairly robust to measurement noise.

  11. Shape-changing interfaces:

    DEFF Research Database (Denmark)

    Rasmussen, Majken Kirkegård; Pedersen, Esben Warming; Petersen, Marianne Graves

    2015-01-01

    Shape change is increasingly used in physical user interfaces, both as input and output. Yet, the progress made and the key research questions for shape-changing interfaces are rarely analyzed systematically. We review a sample of existing work on shape-changing interfaces to address these shortc......Shape change is increasingly used in physical user interfaces, both as input and output. Yet, the progress made and the key research questions for shape-changing interfaces are rarely analyzed systematically. We review a sample of existing work on shape-changing interfaces to address...... these shortcomings. We identify eight types of shape that are transformed in various ways to serve both functional and hedonic design purposes. Interaction with shape-changing interfaces is simple and rarely merges input and output. Three questions are discussed based on the review: (a) which design purposes may...

  12. Self-erecting shapes

    Science.gov (United States)

    Reading, Matthew W.

    2017-07-04

    Technologies for making self-erecting structures are described herein. An exemplary self-erecting structure comprises a plurality of shape-memory members that connect two or more hub components. When forces are applied to the self-erecting structure, the shape-memory members can deform, and when the forces are removed the shape-memory members can return to their original pre-deformation shape, allowing the self-erecting structure to return to its own original shape under its own power. A shape of the self-erecting structure depends on a spatial orientation of the hub components, and a relative orientation of the shape-memory members, which in turn depends on an orientation of joining of the shape-memory members with the hub components.

  13. Beam divergence scaling in neutral beam injectors

    International Nuclear Information System (INIS)

    Holmes, A.J.T.

    1976-01-01

    One of the main considerations in the design of neutral beam injectors is to monimize the divergence of the primary ion beam and hence maximize the beam transport and minimize the input of thermal gas. Experimental measurements of the divergence of a cylindrical ion beam are presented and these measurements are used to analyze the major components of ion beam divergence, namely: space charge expansion, gas-ion scattering, emittance and optical aberrations. The implication of these divergence components in the design of a neutral beam injector system is discussed and a method of maximizing the beam current is described for a given area of source plasma

  14. The Hue of Shapes

    Science.gov (United States)

    Albertazzi, Liliana; Da Pos, Osvaldo; Canal, Luisa; Micciolo, Rocco; Malfatti, Michela; Vescovi, Massimo

    2013-01-01

    This article presents an experimental study on the naturally biased association between shape and color. For each basic geometric shape studied, participants were asked to indicate the color perceived as most closely related to it, choosing from the Natural Color System Hue Circle. Results show that the choices of color for each shape were not…

  15. Dynamical chaos and beam-beam models

    International Nuclear Information System (INIS)

    Izrailev, F.M.

    1990-01-01

    Some aspects of the nonlinear dynamics of beam-beam interaction for simple one-dimensional and two-dimensional models of round and flat beams are discussed. The main attention is paid to the stochasticity threshold due to the overlapping of nonlinear resonances. The peculiarities of a round beam are investigated in view of using the round beams in storage rings to get high luminosity. 16 refs.; 7 figs

  16. Lower hybrid current drive in shaped tokamaks

    International Nuclear Information System (INIS)

    Kesner, J.

    1993-01-01

    A time dependent lower hybrid current drive tokamak simulation code has been developed. This code combines the BALDUR tokamak simulation code and the Bonoli/Englade lower hybrid current drive code and permits the study of the interaction of lower hybrid current drive with neutral beam heating in shaped cross-section plasmas. The code is time dependent and includes the beam driven and bootstrap currents in addition to the current driven by the lower hybrid system. Examples of simulations are shown for the PBX-M experiment which include the effect of cross section shaping on current drive, ballooning mode stabilization by current profile control and sawtooth stabilization. A critical question in current drive calculations is the radial transport of the energetic electrons. The authors have developed a response function technique to calculate radial transport in the presence of an electric field. The consequences of the combined influences of radial diffusion and electric field acceleration are discussed

  17. Flexural Free Vibrations of Multistep Nonuniform Beams

    Directory of Open Access Journals (Sweden)

    Guojin Tan

    2016-01-01

    Full Text Available This paper presents an exact approach to investigate the flexural free vibrations of multistep nonuniform beams. Firstly, one-step beam with moment of inertia and mass per unit length varying as I(x=α11+βxr+4 and m(x=α21+βxr was studied. By using appropriate transformations, the differential equation for flexural free vibration of one-step beam with variable cross section is reduced to a four-order differential equation with constant coefficients. According to different types of roots for the characteristic equation of four-order differential equation with constant coefficients, two kinds of modal shape functions are obtained, and the general solutions for flexural free vibration of one-step beam with variable cross section are presented. An exact approach to solve the natural frequencies and modal shapes of multistep beam with variable cross section is presented by using transfer matrix method, the exact general solutions of one-step beam, and iterative method. Numerical examples reveal that the calculated frequencies and modal shapes are in good agreement with the finite element method (FEM, which demonstrates the solutions of present method are exact ones.

  18. Optical tractor Bessel polarized beams

    International Nuclear Information System (INIS)

    Mitri, F.G.; Li, R.X.; Guo, L.X.; Ding, C.Y.

    2017-01-01

    Axial and transverse radiation force cross-sections of optical tractor Bessel polarized beams are theoretically investigated for a dielectric sphere with particular emphasis on the beam topological charge (or order), half-cone angle and polarization. The angular spectrum decomposition method (ASDM) is used to derive the non-paraxial electromagnetic (EM) field components of the Bessel beams. The multipole expansion method using vector spherical harmonics is utilized and appropriate beam-shape coefficients are derived in order to compute the radiation force cross-sections. The analysis has no limitation to a particular range of frequencies such that the Rayleigh, Mie or geometrical optics regimes can all be considered effectively using the present rigorous formalism. The focus of this investigation is to identify some of the tractor beam conditions so as to achieve retrograde motion of a dielectric sphere located arbitrarily in space. Numerical computations for the axial and transverse radiation force cross-sections are presented for linear, right-circular, radial, azimuthal and mixed polarizations of the individual plane waves forming the Bessel beams of zeroth- and first-order (with positive or negative helicity), respectively. As the sphere shifts off the beam's axis, the axial pulling (tractor) force is weakened. Moreover, the transverse radiation force cross-section field changes with the sphere's size factor ka (where k is the wavenumber and a is the sphere radius). Both stable and unstable equilibrium regions around the beam's axis are found, depending on the choice of ka and the half-cone angle α_0. These results are particularly important in the development of emergent technologies for the photophoretic assembly of optically-engineered (meta)materials with designed properties using optical tractor (vortex) beams, particle manipulation, levitation and positioning, and other applications. - Highlights: • Optical tractor Bessel polarized beams are

  19. Alpha Shapes and Proteins

    DEFF Research Database (Denmark)

    Winter, Pawel; Sterner, Henrik; Sterner, Peter

    2009-01-01

    We provide a unified description of (weighted) alpha shapes, beta shapes and the corresponding simplicialcomplexes. We discuss their applicability to various protein-related problems. We also discuss filtrations of alpha shapes and touch upon related persistence issues.We claim that the full...... potential of alpha-shapes and related geometrical constructs in protein-related problems yet remains to be realized and verified. We suggest parallel algorithms for (weighted) alpha shapes, and we argue that future use of filtrations and kinetic variants for larger proteins will need such implementation....

  20. Plasma shape experiments for an optimized tokamak

    International Nuclear Information System (INIS)

    Hyatt, A.W.; Osborne, T.H.; Lazarus, E.A.

    1994-07-01

    In this paper we present results from recent experiments at DIII-D which measured the plasma stability and confinement performance product, βτ E , in one previously studied and three new plasma shapes. One important goal of these experiments was to identify performance vs shape trends which would identify a shape compatible with both high performance and the planned effort to decrease the power flux to the divertor floor using a closed ''slot'' divertor geometry. power flux to the divertor floor using a closed ''slot'' divertor geometry. The closed divertor hardware must be designed for a reduced set of plasma shapes, so care must be taken to choose the shape that optimizes βτ E and divertor performance. The four shapes studied form a matrix of moderate and high elongations (κ congruent 1.8 and 2.1) and low and high triangularities (δ congruent 0.3 and 0.9). All configurations were double-null diverted (DND), held fixed during a shot, with neutral beam heating. The shapes span a range of X-point locations compatible with the envisioned closed divertor. We find that from shape to shape, a shot's transient normalized performance, β N H, where β N ≡ β/(I p )/aB T and H ≡ τ E /τ E ITER-89P , increases strongly with triangularity, but depends only weakly on elongation. However, the normalized performance during quasi stationary ELMing H-mode, to which these discharges eventually relax, is insensitive to both triangularity and elongation. The moderate elongation, high triangularity DND shape is shown to be near optimum for future studies on DIII-D

  1. Plasma shape experiments for an optimized tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Hyatt, A.W.; Osborne, T.H. [General Atomics, San Diego, CA (United States); Lazarus, E.A. [Oak Ridge National Lab., TN (United States)

    1994-12-31

    In this paper we present results from recent experiments at DIII-D which measured the plasma stability and confinement performance product, {beta}{sub {tau}E}, in one previously studied and three new plasma shapes. One important goal of these experiments was to identify performance vs shape trends which would identify a shape compatible with both high performance and the planned effort to decrease the power flux to the divertor floor using a closed `slot` divertor geometry. The closed divertor hardware must be designed for a reduced set of plasma shapes, so care must be taken to choose the shape that optimizes {beta}{sub {tau}E} and divertor performance. The four shapes studied form a matrix of moderate and high elongations ({kappa} {approx_equal} 1.8 and 2.1) and low and high triangularities ({delta} {approx_equal} 0.3 and 0.9). All configurations were double-null diverted (DND), held fixed during a shot, with neutral beam heating. The shapes span a range of X-point locations compatible with the envisioned closed divertor. We find that from shape to shape, a shot`s transient normalized performance, {beta}{sub N}H, where {beta}{sub N} = {beta}/(I{sub p}/aB{sub T}) and H = {tau}{sub E}/{tau}{sub E}{sup ITER-89P}, increases strongly with triangularity, but depends only weakly on elongation. However, the normalized performance during quasi stationary ELMing H-mode, to which these discharges eventually relax, is insensitive to both triangularity and elongation. The moderate elongation, high triangularity DND shape is shown to be near optimum for future studies on DIII-D. (author) 7 refs., 7 figs.

  2. Beam propagation

    International Nuclear Information System (INIS)

    Hermansson, B.R.

    1989-01-01

    The main part of this thesis consists of 15 published papers, in which the numerical Beam Propagating Method (BPM) is investigated, verified and used in a number of applications. In the introduction a derivation of the nonlinear Schroedinger equation is presented to connect the beginning of the soliton papers with Maxwell's equations including a nonlinear polarization. This thesis focuses on the wide use of the BPM for numerical simulations of propagating light and particle beams through different types of structures such as waveguides, fibers, tapers, Y-junctions, laser arrays and crystalline solids. We verify the BPM in the above listed problems against other numerical methods for example the Finite-element Method, perturbation methods and Runge-Kutta integration. Further, the BPM is shown to be a simple and effective way to numerically set up the Green's function in matrix form for periodic structures. The Green's function matrix can then be diagonalized with matrix methods yielding the eigensolutions of the structure. The BPM inherent transverse periodicity can be untied, if desired, by for example including an absorptive refractive index at the computational window edges. The interaction of two first-order soliton pulses is strongly dependent on the phase relationship between the individual solitons. When optical phase shift keying is used in coherent one-carrier wavelength communication, the fiber attenuation will suppress or delay the nonlinear instability. (orig.)

  3. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  4. Collimator for the SPS extracted beam

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    This is a water cooled copper collimator (TCSA) which has exactly the shape of the cross section of the downstream magnetic beam splitter. Parts of the blown up primary proton beam pass above/below and left through this collimator. A small part of the protons is absorbed in the thin copper wedges. In this way the downstream magnetic splitter of the same cross section receives already a beam where its magnetic wedges are no longer hit by protons. The upstream, water cooled collimator, more resistant to protons, has cast a 'shadow' onto the downstream magnetic splitter, less resistant to protons. Gualtero Del Torre stands on the left.

  5. Laser beam propagation through random media

    CERN Document Server

    Andrews, Larry C

    2005-01-01

    Since publication of the first edition of this text in 1998, there have been several new, important developments in the theory of beam wave propagation through a random medium, which have been incorporated into this second edition. Also new to this edition are models for the scintillation index under moderate-to-strong irradiance fluctuations; models for aperture averaging based on ABCD ray matrices; beam wander and its effects on scintillation; theory of partial coherence of the source; models of rough targets for ladar applications; phase fluctuations; analysis of other beam shapes; plus exp

  6. ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

    Science.gov (United States)

    Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

    2012-03-01

    the ion source by high voltage applied to the extraction and accelerating grids. The current distribution of a single beamlet emitted from a single pore of IOS depends on the shape of the plasma boundary in the emission region. Total beam extracted by IOS is calculated at every point of 3D mesh as sum of all contributions from each grid pore. The code effectively unifies the ion beam formation, extraction and neutralization processes with neutral beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. Running time: 10 min for a standard run.

  7. Production of an {sup 15}O beam using a stable oxygen ion beam for in-beam PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Akram, E-mail: mohammadi.akram@qst.go.jp; Yoshida, Eiji; Tashima, Hideaki; Nishikido, Fumihiko; Inaniwa, Taku; Kitagawa, Atsushi; Yamaya, Taiga

    2017-03-21

    In advanced ion therapy, the {sup 15}O ion beam is a promising candidate to treat hypoxic tumors and simultaneously monitor the delivered dose to a patient using PET imaging. This study aimed at production of an {sup 15}O beam by projectile fragmentation of a stable {sup 16}O beam in an optimal material, followed by in-beam PET imaging using a prototype OpenPET system, which was developed in the authors’ group. The study was carried out in three steps: selection of the optimal target based on the highest production rate of {sup 15}O fragments; experimental production of the beam using the optimal target in the Heavy Ion Medical Accelerator Chiba (HIMAC) secondary beam course; and realization of in-beam PET imaging for the produced beam. The optimal target evaluations were done using the Monte Carlo simulation code PHITS. The fluence and mean energy of the secondary particles were simulated and the optimal target was selected based on the production rate of {sup 15}O fragments. The highest production rate of {sup 15}O was observed for a liquid hydrogen target, 3.27% for a 53 cm thick target from the {sup 16}O beam of 430 MeV/u. Since liquid hydrogen is not practically applicable in the HIMAC secondary beam course a hydrogen-rich polyethylene material, which was the second optimal target from the simulation results, was selected as the experimental target. Three polyethylene targets with thicknesses of 5, 11 or 14 cm were used to produce the {sup 15}O beam without any degrader in the beam course. The highest production rate was measured as around 0.87% for the 11 cm thick polyethylene target from the {sup 16}O beam of 430 MeV/u when the angular acceptance and momentum acceptance were set at ±13 mrad and ±2.5%, respectively. The purity of the produced beam for the three targets were around 75%, insufficient for clinical application, but it was increased to 97% by inserting a wedge shape aluminum degrader with a thickness of 1.76 cm into the beam course and that is

  8. Production of an 15O beam using a stable oxygen ion beam for in-beam PET imaging

    Science.gov (United States)

    Mohammadi, Akram; Yoshida, Eiji; Tashima, Hideaki; Nishikido, Fumihiko; Inaniwa, Taku; Kitagawa, Atsushi; Yamaya, Taiga

    2017-03-01

    In advanced ion therapy, the 15O ion beam is a promising candidate to treat hypoxic tumors and simultaneously monitor the delivered dose to a patient using PET imaging. This study aimed at production of an 15O beam by projectile fragmentation of a stable 16O beam in an optimal material, followed by in-beam PET imaging using a prototype OpenPET system, which was developed in the authors' group. The study was carried out in three steps: selection of the optimal target based on the highest production rate of 15O fragments; experimental production of the beam using the optimal target in the Heavy Ion Medical Accelerator Chiba (HIMAC) secondary beam course; and realization of in-beam PET imaging for the produced beam. The optimal target evaluations were done using the Monte Carlo simulation code PHITS. The fluence and mean energy of the secondary particles were simulated and the optimal target was selected based on the production rate of 15O fragments. The highest production rate of 15O was observed for a liquid hydrogen target, 3.27% for a 53 cm thick target from the 16O beam of 430 MeV/u. Since liquid hydrogen is not practically applicable in the HIMAC secondary beam course a hydrogen-rich polyethylene material, which was the second optimal target from the simulation results, was selected as the experimental target. Three polyethylene targets with thicknesses of 5, 11 or 14 cm were used to produce the 15O beam without any degrader in the beam course. The highest production rate was measured as around 0.87% for the 11 cm thick polyethylene target from the 16O beam of 430 MeV/u when the angular acceptance and momentum acceptance were set at ±13 mrad and ±2.5%, respectively. The purity of the produced beam for the three targets were around 75%, insufficient for clinical application, but it was increased to 97% by inserting a wedge shape aluminum degrader with a thickness of 1.76 cm into the beam course and that is sufficiently high. In-beam PET imaging was also

  9. Horizontal beam tubes in FRM-II

    International Nuclear Information System (INIS)

    Coors, D.; Vanvor, D.

    2001-01-01

    The new research reactor in Garching FRM-II is equipped with 10 leak tight horizontal beam tubes (BT1 - BT10), each of them consisting of a beam tube structure taking an insert with neutron channels. The design of all beam tube structures is similar whereas the inserts are adapted to the special requirements of the using of each beam tube. Inside the reflector tank the beam tube structures are shaped by the inner cones which are made of Al-alloy with circular and rectangular cross sections. They are located in the region of maximum neutron flux (exception BT10), they are directly connected to the flanges of the reflector tank, their lengths are about 1.5 m (exception BT10) and their axes are directed tagentially to the core centre thus contributing to a low γ-noise at the experiments. (orig.)

  10. Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hyojae, E-mail: lkcom@ibs.re.kr; Jin, Hyunchang; Jang, Ji-Ho; Hong, In-Seok [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of)

    2016-02-15

    A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.

  11. Modified M20 Beam Position Monitor Testing

    Science.gov (United States)

    Koros, Jessica; Musson, John

    2017-09-01

    Beam position monitors (BPMs) are used to measure lateral beam position. Two pairs of modified wire BPMs are being evaluated for installation into the injector at Jefferson Lab (JLab). The BPMs were coated with a Non-Evaporable Getter (NEG) to aid in pumping at the electron gun, as an ultra-high vacuum is required to protect the gun and to avoid scattering the beam. Beam in the injector has a large diameter, allowing extraction of second moments to give information about beam profile and emittance. The purpose of this project is to determine the effects of NEG coating on the BPMs and to calculate second moments from beam models on the Goubau Line (G-Line). Using the G-Line, scans of the BPMs were taken before and after NEG coating. Each scan produced an electrical field map, which characterizes properties of the BPM, including scale factors and coupling. Second moments were calculated using superposition of previous scan data, and verification of this method was attempted using several beam models. Results show the BPMs responded well to NEG and that measurement of second moments is possible. Once the BPMs are installed, they will enhance gun vacuum and enable monitoring of shape and trajectory of the beam as it exits the electron gun to ensure quality beam for experiments. This work is made possible through support from NSF award 1659177 to Old Dominion University.

  12. Influence of laser beam profile on electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Cuk, S. M.; Radonjic, M.; Krmpot, A. J.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M.

    2010-01-01

    We compared, experimentally and theoretically, Hanle electromagnetically induced absorption (EIA) obtained using Gaussian and Π-shaped laser beams 3 mm in diameter. The study was done by measuring the transmission of a laser locked to the F g =2→F e =3 transition at the D 2 line of 87 Rb in a vacuum cell. EIA linewidths obtained for the two laser profiles were significantly different in the range of laser intensities 1-4 mW/cm 2 . EIA with the Π-shaped laser beam has a broad intensity maximum and linewidths larger than those obtained with the Gaussian beam profile. We also studied Hanle EIA by measuring the transmission of selected segments of the entire laser beam by placing a small movable aperture in front of the detector. Waveforms so obtained in Hanle EIA resonances were strongly influenced both by the radial distance of the transmitted segment from the beam center and by the radial profile of the laser beam. We show that outer regions of Gaussian beam, and central regions of the Π-shaped beam generate the narrowest lines. The different behaviors of EIA owing to different beam profiles revealed by both theory and experiment indicate the importance of the radial profile of the laser beam for proper modeling of coherent effects in alkali metal vapors.

  13. Shape memory alloys

    International Nuclear Information System (INIS)

    Kaszuwara, W.

    2004-01-01

    Shape memory alloys (SMA), when deformed, have the ability of returning, in certain circumstances, to their initial shape. Deformations related to this phenomenon are for polycrystals 1-8% and up to 15% for monocrystals. The deformation energy is in the range of 10 6 - 10 7 J/m 3 . The deformation is caused by martensitic transformation in the material. Shape memory alloys exhibit one directional or two directional shape memory effect as well as pseudoelastic effect. Shape change is activated by temperature change, which limits working frequency of SMA to 10 2 Hz. Other group of alloys exhibit magnetic shape memory effect. In these alloys martensitic transformation is triggered by magnetic field, thus their working frequency can be higher. Composites containing shape memory alloys can also be used as shape memory materials (applied in vibration damping devices). Another group of composite materials is called heterostructures, in which SMA alloys are incorporated in a form of thin layers The heterostructures can be used as microactuators in microelectromechanical systems (MEMS). Basic SMA comprise: Ni-Ti, Cu (Cu-Zn,Cu-Al, Cu-Sn) and Fe (Fe-Mn, Fe-Cr-Ni) alloys. Shape memory alloys find applications in such areas: automatics, safety and medical devices and many domestic appliances. Currently the most important appears to be research on magnetic shape memory materials and high temperature SMA. Vital from application point of view are composite materials especially those containing several intelligent materials. (author)

  14. Crystalline beams

    International Nuclear Information System (INIS)

    Schiffer, J.P.

    1989-01-01

    Ions in a storage ring are confined to a mean orbit by focusing elements. To a first approximation these may be described by a constant harmonic restoring force: F = -Kr. If the particles in the frame moving along with the beam have small random thermal energies, then they will occupy a cylindrical volume around the mean orbit and the focusing force will be balanced by that from the mutual repulsion of the particles. Inside the cylinder only residual two-particle interactions will play a significant role and some form of ordering might be expected to take place. The results of some of the first MD calculations showed a surprising result: not only were the particles arranged in the form of a tube, but they formed well-defined layers: concentric shells, with the particles in each shell arranged in a hexagonal lattice that is characteristic of two-dimensional Coulomb systems. This paper discusses the condense layer structure

  15. Measurement of electron beams profile of pierce type electron source using sensor of used Tv tube

    International Nuclear Information System (INIS)

    Darsono; Suhartono; Suprapto; Elin Nuraini

    2015-01-01

    The measurement of an electron beam profile has been performed using electron beam monitor based on method of phosphorescent materials. The main components of the electron beam monitor consists of a fluorescent sensor using a used Tv tube, CCTV camera to record images on a Tv screen, video adapter as interface between CCTV and laptop, and the laptop as a viewer and data processing. Two Pierce-type electron sources diode and triode was measured the shape of electron beam profile in real time. Results of the experiments showed that the triode electron source of Pierce type gave the shape of electron beam profiles better than that of the diode electron source .The anode voltage is not so influential on the beam profile shape. The focused voltage in the triode electron source is so influence to the shape of the electron beam profile, but above 5 kV no great effect. It can be concluded that the electron beam monitor can provide real time observations and drawings shape of the electron beam profile displayed on the used Tv tube glass screen which is the real picture of the shape of the electron beam profile. Triode electron source produces a better electron beam profile than that of the diode electron source. (author)

  16. A real-time intercepting beam-profile monitor for a medical cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Hendriks, C.; Uittenbosch, T.; Cameron, D.; Kellogg, S.; Gray, D.; Buckley, K.; Schaffer, P.; Verzilov, V.; Hoehr, C. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada)

    2013-11-15

    There is a lack of real-time continuous beam-diagnostic tools for medical cyclotrons due to high power deposition during proton irradiation. To overcome this limitation, we have developed a profile monitor that is capable of providing continuous feedback about beam shape and current in real time while it is inserted in the beam path. This enables users to optimize the beam profile and observe fluctuations in the beam over time with periodic insertion of the monitor.

  17. Electron beam directed energy device and methods of using same

    Science.gov (United States)

    Retsky, Michael W.

    2007-10-16

    A method and apparatus is disclosed for an electron beam directed energy device. The device consists of an electron gun with one or more electron beams. The device includes one or more accelerating plates with holes aligned for beam passage. The plates may be flat or preferably shaped to direct each electron beam to exit the electron gun at a predetermined orientation. In one preferred application, the device is located in outer space with individual beams that are directed to focus at a distant target to be used to impact and destroy missiles. The aimings of the separate beams are designed to overcome Coulomb repulsion. A method is also presented for directing the beams to a target considering the variable terrestrial magnetic field. In another preferred application, the electron beam is directed into the ground to produce a subsurface x-ray source to locate and/or destroy buried or otherwise hidden objects including explosive devices.

  18. The shape of nuclei

    International Nuclear Information System (INIS)

    Mackintosh, R.S.

    1977-01-01

    For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)

  19. Research in Shape Analysis

    CERN Document Server

    Leonard, Kathryn; Tari, Sibel; Hubert, Evelyne; Morin, Geraldine; El-Zehiry, Noha; Chambers, Erin

    2018-01-01

    Based on the second Women in Shape (WiSH) workshop held in Sirince, Turkey in June 2016, these proceedings offer the latest research on shape modeling and analysis and their applications. The 10 peer-reviewed articles in this volume cover a broad range of topics, including shape representation, shape complexity, and characterization in solving image-processing problems. While the first six chapters establish understanding in the theoretical topics, the remaining chapters discuss important applications such as image segmentation, registration, image deblurring, and shape patterns in digital fabrication. The authors in this volume are members of the WiSH network and their colleagues, and most were involved in the research groups formed at the workshop. This volume sheds light on a variety of shape analysis methods and their applications, and researchers and graduate students will find it to be an invaluable resource for further research in the area.

  20. Perspectives in shape analysis

    CERN Document Server

    Bruckstein, Alfred; Maragos, Petros; Wuhrer, Stefanie

    2016-01-01

    This book presents recent advances in the field of shape analysis. Written by experts in the fields of continuous-scale shape analysis, discrete shape analysis and sparsity, and numerical computing who hail from different communities, it provides a unique view of the topic from a broad range of perspectives. Over the last decade, it has become increasingly affordable to digitize shape information at high resolution. Yet analyzing and processing this data remains challenging because of the large amount of data involved, and because modern applications such as human-computer interaction require real-time processing. Meeting these challenges requires interdisciplinary approaches that combine concepts from a variety of research areas, including numerical computing, differential geometry, deformable shape modeling, sparse data representation, and machine learning. On the algorithmic side, many shape analysis tasks are modeled using partial differential equations, which can be solved using tools from the field of n...

  1. Approaching maximal performance of longitudinal beam compression in induction accelerator drivers

    International Nuclear Information System (INIS)

    Mark, J.W.K.; Ho, D.D.M.; Brandon, S.T.; Chang, C.L.; Drobot, A.T.; Faltens, A.; Lee, E.P.; Krafft, G.A.

    1986-01-01

    Longitudinal beam compression occurs before final focus and fusion chamber beam transport and is a key process determining initial conditions for final focus hardware. Determining the limits for maximal performance of key accelerator components is an essential element of the effort to reduce driver costs. Studies directed towards defining the limits of final beam compression including considerations such as maximal available compression, effects of longitudinal dispersion and beam emittance, combining pulse-shaping with beam compression to reduce the total number of beam manipulators, etc., are given. Several possible techniques are illustrated for utilizing the beam compression process to provide the pulse shapes required by a number of targets. Without such capabilities to shape the pulse, an additional factor of two or so of beam energy would be required by the targets

  2. Beam-Beam Interaction Studies at LHC

    CERN Document Server

    Schaumann, Michaela; Alemany Fernandez, R

    2011-01-01

    The beam-beam force is one of the most important limiting factors in the performance of a collider, mainly in the delivered luminosity. Therefore, it is essential to measure the effects in LHC. Moreover, adequate understanding of LHC beam-beam interaction is of crucial importance in the design phases of the LHC luminosity upgrade. Due to the complexity of this topic the work presented in this thesis concentrates on the beam-beam tune shift and orbit effects. The study of the Linear Coherent Beam-Beam Parameter at the LHC has been determined with head-on collisions with small number of bunches at injection energy (450 GeV). For high bunch intensities the beam-beam force is strong enough to expect orbit effects if the two beams do not collide head-on but with a crossing angle or with a given offset. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are as well ...

  3. Shaping of planetary nebulae

    International Nuclear Information System (INIS)

    Balick, B.

    1987-01-01

    The phases of stellar evolution and the development of planetary nebulae are examined. The relation between planetary nebulae and red giants is studied. Spherical and nonspherical cases of shaping planetaries with stellar winds are described. CCD images of nebulae are analyzed, and it is determined that the shape of planetary nebulae depends on ionization levels. Consideration is given to calculating the distances of planetaries using radio images, and molecular hydrogen envelopes which support the wind-shaping model of planetary nebulae

  4. Interesting detector shapes for 3rd generation CT

    Energy Technology Data Exchange (ETDEWEB)

    Kachelriess, Marc [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. of Medical Physics (IMP)

    2011-07-01

    Third generation CT scanners typically comprise detectors which are flat or whose shape is the segment of a cylinder or a sphere that is focussed onto the focal spot of the X-ray source. There appear to be two design criteria that favor this choice of detector shape. One is the possibility of performing fan-beam and cone-beam filtered backprojection in the native geometry (without rebinning) and the other criterium is to enable the use of focussed anti scatter grids. It is less known, however, that other detector shapes may also have these properties. While these designs have been evaluated for 2D CT from a rather theoretical standpoint more than one decade ago we revisit and generalize these considerations, extend them to 3D circular, sequential and spiral cone-beam CT and propose an optimal design in terms of detector costs. (orig.)

  5. Radiation processing technology for preparation of fine shaped biomedical materials

    Energy Technology Data Exchange (ETDEWEB)

    Kumakura, M.; Yoshida, M.; Asano, M. (Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment); Yamanaka, H. (Gunma Univ., Maebashi (Japan). School of Medicine)

    1992-06-01

    Radiation processing technology for the preparation of fine shaped biomedical materials was studied from the aspect of a development of the technology and its application. Electron beam irradiation technology was applied to the preparation of fine shaped biomedical materials such as thin polymer films in diagnosis, in which enzyme and antibody were used as a bioactive substance. Electron beam cast-polymerization and electron beam repeat surface-polymerization, that are surface irradiation techniques of homogeneous hydrophilic monomer solution containing enzymes made it possible to form the immobilized antibody films. In this technique, the films with various thicknesses (50-500 [mu]m) were obtained by regulating the electron beam energy. The thin polymer films immobilizing anti-[alpha]-fetoprotein were evaluated from the aspect of immunoagents for diagnosis of liver cancer. (Author).

  6. Beam halo in high-intensity beams

    International Nuclear Information System (INIS)

    Wangler, T.P.

    1993-01-01

    In space-charge dominated beams the nonlinear space-charge forces produce a filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. The beam-halo is of concern for a next generation of cw, high-power proton linacs that could be applied to intense neutron generators for nuclear materials processing. The author describes what has been learned about beam halo and the evolution of space-charge dominated beams using numerical simulations of initial laminar beams in uniform linear focusing channels. Initial results are presented from a study of beam entropy for an intense space-charge dominated beam

  7. Beam-beam issues in asymmetric colliders

    International Nuclear Information System (INIS)

    Furman, M.A.

    1992-07-01

    We discuss generic beam-beam issues for proposed asymmetric e + - e - colliders. We illustrate the issues by choosing, as examples, the proposals by Cornell University (CESR-B), KEK, and SLAC/LBL/LLNL (PEP-II)

  8. Laser Beam Shaping XIII, Proceedings of SPIE Vol. 8490

    CSIR Research Space (South Africa)

    Forbes, A

    2012-09-01

    Full Text Available .1117/12.2013615 Proc. of SPIE Vol. 8490 849001-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 10/17/2012 Terms of Use: http://spiedl.org/terms The papers included in this volume were part of the technical conference cited on the cover and title..., Bellingham, Washington 98227-0010 USA Telephone +1 360 676 3290 (Pacific Time)? Fax +1 360 647 1445 SPIE.org Copyright ? 2012, Society of Photo-Optical Instrumentation Engineers. Copying of material in this book for internal or personal use...

  9. Synchronization circuit for shaping electron beam picosecond pulses

    International Nuclear Information System (INIS)

    Pavlov, Yu.S.; Solov'ev, N.G.; Tomnikov, A.P.

    1985-01-01

    A fast response circuit of modulator trigger pulse synchronization of a deflector of the electron linear accelerator at 13 MeV with the given phase of HF-voltage is described. The circuit is constructed using K500 and K100 integrated emitter-coupled logics circuits. Main parameters of a synchropulse are duration of 20-50 ns, pulse rise time of 1-5 ns, pulse amplitude >=10 V, delay instability of a trigger pulse <=+-0.05 ns. A radiopulse with 3 μs duration, 5 V amplitude and 400 Hz frequency enters the circuit input. The circuit can operate at both pulsed operation and continuous modes

  10. Mid-infrared beam splitter for ultrashort pulses.

    Science.gov (United States)

    Somma, Carmine; Reimann, Klaus; Woerner, Michael; Kiel, Thomas; Busch, Kurt; Braun, Andreas; Matalla, Mathias; Ickert, Karina; Krüger, Olaf

    2017-08-01

    A design is presented for a beam splitter suitable for ultrashort pulses in the mid-infrared and terahertz spectral range consisting of a structured metal layer on a diamond substrate. Both the theory and experiment show that this beam splitter does not distort the temporal pulse shape.

  11. Apparatus for the deflection of an electron beam

    International Nuclear Information System (INIS)

    1976-01-01

    An X-ray apparatus is described that can be used in tomography. The design of the X-ray tube is the main subject of the patent with emphasis on the way of beam shaping and the control of the beam profile

  12. Deflecting cavity for beam diagnostics at Cornell ERL injector

    International Nuclear Information System (INIS)

    Belomestnykh, Sergey; Bazarov, Ivan; Shemelin, Valery; Sikora, John; Smolenski, Karl; Veshcherevich, Vadim

    2010-01-01

    A single-cell, 1300-MHz, TM110-like mode vertically deflecting cavity is designed and built for beam slice emittance measurements, and to study the temporal response of negative electron affinity photocathodes in the ERL injector at Cornell University. We describe the cavity shape optimization procedure, RF and mechanical design, its performance with beam.

  13. Definition and characterization of focused beams. Practical aspects

    International Nuclear Information System (INIS)

    Vadder, D. de; Saglio, R.; Birac, A.M.

    1982-08-01

    Characterization of ultrasonic beams by means of echos coming back from targets is very often used. Results are not independent of shape and size of those targets. Measuring echos from inclined disk-like targets let appear fluctuating results in the very front part of beams

  14. Tokamak Fusion Test Reactor neutral beam injection system vacuum chamber

    International Nuclear Information System (INIS)

    Pedrotti, L.R.

    1977-01-01

    Most of the components of the Neutral Beam Lines of the Tokamak Fusion Test Reactor (TFTR) will be enclosed in a 50 cubic meter box-shaped vacuum chamber. The chamber will have a number of unorthodox features to accomodate both neutral beam and TFTR requirements. The design constraints, and the resulting chamber design, are presented

  15. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, Vincenzo, E-mail: vincenzo.grillo@nano.cnr.it [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); CNR-IMEM Parco Area delle Scienze 37/A, I-43124 Parma (Italy); Carlo Gazzadi, Gian [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Karimi, Ebrahim [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Mafakheri, Erfan [Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy); Boyd, Robert W. [Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada); Frabboni, Stefano [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); Dipartimento di Fisica Informatica e Matematica, Università di Modena e Reggio Emilia, via G Campi 213/a, I-41125 Modena (Italy)

    2014-01-27

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.

  16. Numerical simulation on beam breakup unstability of linear induction accelerator

    International Nuclear Information System (INIS)

    Zhang Kaizhi; Wang Huacen; Lin Yuzheng

    2003-01-01

    A code is written to simulate BBU in induction linac according to theoretical analysis. The general form of evolution of BBU in induction linac is investigated at first, then the effect of related parameters on BBU is analyzed, for example, the alignment error, oscillation frequency of beam centroid, beam pulse shape and acceleration gradient. At last measures are put forward to damp beam breakup unstability (BBU)

  17. Highly efficient electron vortex beams generated by nanofabricated phase holograms

    International Nuclear Information System (INIS)

    Grillo, Vincenzo; Carlo Gazzadi, Gian; Karimi, Ebrahim; Mafakheri, Erfan; Boyd, Robert W.; Frabboni, Stefano

    2014-01-01

    We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science

  18. Metaoptics for Spectral and Spatial Beam Manipulation

    Science.gov (United States)

    Raghu Srimathi, Indumathi

    Laser beam combining and beam shaping are two important areas with applications in optical communications, high power lasers, and atmospheric propagation studies. In this dissertation, metaoptical elements have been developed for spectral and spatial beam shaping, and multiplexing. Beams carrying orbital angular momentum (OAM), referred to as optical vortices, have unique propagation properties. Optical vortex beams carrying different topological charges are orthogonal to each other and have low inter-modal crosstalk which allows for them to be (de)multiplexed. Efficient spatial (de)multiplexing of these beams have been carried out by using diffractive optical geometrical coordinate transformation elements. The spatial beam combining technique shown here is advantageous because the efficiency of the system is not dependent on the number of OAM states being combined. The system is capable of generating coaxially propagating beams in the far-field and the beams generated can either be incoherently or coherently multiplexed with applications in power scaling and dynamic intensity profile manipulations. Spectral beam combining can also be achieved with the coordinate transformation elements. The different wavelengths emitted by fiber sources can be spatially overlapped in the far-field plane and the generated beams are Bessel-Gauss in nature with enhanced depth of focus properties. Unique system responses and beam shapes in the far-field can be realized by controlling amplitude, phase, and polarization at the micro-scale. This has been achieved by spatially varying the structural parameters at the subwavelength scale and is analogous to local modification of material properties. With advancements in fabrication technology, it is possible to control not just the lithographic process, but also the deposition process. In this work, a unique combination of spatial structure variations in conjunction with the conformal coating properties of an atomic layer deposition tool

  19. Device for the collimation of a high-energy beam, in particular a X-ray beam

    International Nuclear Information System (INIS)

    Peyser, L.F.

    1976-01-01

    The design of apertures made of radiation-absorbing material intended for limiting an aperture for a radiation beam of high energy, in particular an X-ray beam is claimed. The apertures are shaped as trapezoids, are held movably, and are adjustable by means of a control device. (UWI) [de

  20. Shape from touch

    NARCIS (Netherlands)

    Kappers, A.M.L.; Bergmann Tiest, W.M.

    2014-01-01

    The shape of objects cannot only be recognized by vision, but also by touch. Vision has the advantage that shapes can be seen at a distance, but touch has the advantage that during exploration many additional object properties become available, such as temperature (Jones, 2009), texture (Bensmaia,

  1. Odd Shape Out

    Science.gov (United States)

    Cady, Jo Ann; Wells, Pamela

    2016-01-01

    The Odd Shape Out task was an open-ended problem that engaged students in comparing shapes based on their properties. Four teachers submitted the work of 116 students from across the country. This article compares various student's responses to the task. The problem allowed for differentiation, as shown by the many different ways that students…

  2. Discriminative Shape Alignment

    DEFF Research Database (Denmark)

    Loog, M.; de Bruijne, M.

    2009-01-01

    , not taking into account that eventually the shapes are to be assigned to two or more different classes. This work introduces a discriminative variation to well-known Procrustes alignment and demonstrates its benefit over this classical method in shape classification tasks. The focus is on two...

  3. Evolution of nuclear shape in the light radon isotopes

    CERN Multimedia

    Reiter, P; Blazhev, A A; Kruecken, R; Rahkila, P J; Grahn, T; Wadsworth, R; Gernhaeuser, R A; Bree, N C F; Habs, D; Jenkins, D G; Huyse, M L

    2008-01-01

    We propose to carry out Coulomb excitation of post-accelerated beams of $^{202,204}$ Rn from the REX-ISOLDE facility. The aim of this study is to expand our understanding of nuclear shape coexistence, which has been increasingly well-established in the light mercury and lead nuclei to these very heavy nuclei. Such an extension will provide stringent tests of nuclear models of collectivity and shape coexistence in a previously-inaccessible heavy mass region. REX- ISOLDE is the only facility worldwide at the present time which can provide accelerated beams of such heavy radioactive nuclei.

  4. Modular low-voltage electron beams

    International Nuclear Information System (INIS)

    Berejka, A.J.; Avnery, Tovi; Carlson, Carl

    2004-01-01

    Modular, low-voltage systems have simplified electron beam (EB) technology for industrial uses and for research and development. Modular EB units are produced in quantity as sealed systems that are evacuated at the factory eliminating the need for vacuum pumps at the point of use. A simple plug-out--plug-in method of replacement eliminates downtime for servicing. Use of ultra-thin beam windows (<10 μm of titanium foil), solid-state 19 in. (48 cm) rack-mounted power supplies, an innovative design to extract and spread the beam (enabling systems to be placed adjacent to each other to extend beam width) and touch-screen computer controls, combine for ease of use and electrical transfer efficiency at voltages that can be varied between 80 and 150 kV and with high beam currents (up to 40 mA across the 25 cm window). These electron systems are available in three widths, the standard 25 cm and new 5 and 40 cm beams. Traditional uses in the graphic arts and coatings areas as well as uses in surface sterilization have found these compact, lightweight (approximately 15 kg) modular beams of interest. Units have been configured around complex shapes to enable three-dimensional surface curing (as for coatings on aluminum tubing) to be achieved at high production rates. Details of the beam construction and some industrial uses are discussed

  5. Modular low-voltage electron beams

    Science.gov (United States)

    Berejka, Anthony J.; Avnery, Tovi; Carlson, Carl

    2004-09-01

    Modular, low-voltage systems have simplified electron beam (EB) technology for industrial uses and for research and development. Modular EB units are produced in quantity as sealed systems that are evacuated at the factory eliminating the need for vacuum pumps at the point of use. A simple plug-out—plug-in method of replacement eliminates downtime for servicing. Use of ultra-thin beam windows (innovative design to extract and spread the beam (enabling systems to be placed adjacent to each other to extend beam width) and touch-screen computer controls, combine for ease of use and electrical transfer efficiency at voltages that can be varied between 80 and 150 kV and with high beam currents (up to 40 mA across the 25 cm window). These electron systems are available in three widths, the standard 25 cm and new 5 and 40 cm beams. Traditional uses in the graphic arts and coatings areas as well as uses in surface sterilization have found these compact, lightweight (approximately 15 kg) modular beams of interest. Units have been configured around complex shapes to enable three-dimensional surface curing (as for coatings on aluminum tubing) to be achieved at high production rates. Details of the beam construction and some industrial uses are discussed.

  6. The LBL multiple beam experiments

    International Nuclear Information System (INIS)

    Fessenden, T.J.; Keefe, D.; Kim, C.; Meuth, H.; Warwick, A.

    1987-01-01

    The multiple-beam induction linac approach to a heavy ion driver for inertial confinement fusion features continuous current amplification along the accelerator and a minimum of beam manipulations from source to pellet. Current amplification and bunch length control require careful shaping of the accelerating voltages. MBE-4 is designed as a four-beam induction linac that models much of the accelerator physics of the electrostatically focused section of a significantly longer induction accelerator. Four space-charge-dominated Cs + beams, initially about one meter in length at a current of 13 mA, are focused by electrostatic quadrupoles and accelerated in parallel from 200 to nearly 600 keV. The energy will reach approximately one MeV when the accelerator is complete. Experiments have proceeded in parallel with the construction of the apparatus which began in FY 85 and is now more than half complete. The results show a current amplification, so far, by a factor of 2.8 in good agreement with the longitudinal acceleration calculations. 9 refs

  7. Broad beam ion sources and some surface processes

    International Nuclear Information System (INIS)

    Neumann, H.; Scholze, F.; Tarz, M.; Schindler, A.; Wiese, R.; Nestler, M.; Blum, T.

    2005-01-01

    Modern broad-beam multi-aperture ion sources are widely used in material and surface technology applications. Customizing the generated ion beam properties (i. e. the ion current density profile) for specific demands of the application is a main challenge in the improvement of the ion beam technologies. First we introduce ion sources based on different plasma excitation principles shortly. An overview of source plasma and ion beam measurement methods deliver input data for modelling methods. This beam profile modelling using numerical trajectory codes and the validation of the results by Faraday cup measurements as a basis for ion beam profile design are described. Furthermore possibilities for ex situ and in situ beam profile control are demonstrated, like a special method for in situ control of a linear ion source beam profile, a grid modification for circular beam profile design and a cluster principle for broad beam sources. By means of these methods, the beam shape may be adapted to specific technological demands. Examples of broad beam source application in ion beam figuring of optical surfaces, modification of stainless steel, photo voltaic processes and deposition of EUVL-multilayer stacks are finally presented. (Author)

  8. A symplectic coherent beam-beam model

    International Nuclear Information System (INIS)

    Furman, M.A.

    1989-05-01

    We consider a simple one-dimensional model to study the effects of the beam-beam force on the coherent dynamics of colliding beams. The key ingredient is a linearized beam-beam kick. We study only the quadrupole modes, with the dynamical variables being the 2nd-order moments of the canonical variables q, p. Our model is self-consistent in the sense that no higher order moments are generated by the linearized beam-beam kicks, and that the only source of violation of symplecticity is the radiation. We discuss the round beam case only, in which vertical and horizontal quantities are assumed to be equal (though they may be different in the two beams). Depending on the values of the tune and beam intensity, we observe steady states in which otherwise identical bunches have sizes that are equal, or unequal, or periodic, or behave chaotically from turn to turn. Possible implications of luminosity saturation with increasing beam intensity are discussed. Finally, we present some preliminary applications to an asymmetric collider. 8 refs., 8 figs

  9. Antihydrogen Beams

    Science.gov (United States)

    Yamazaki, Yasunori; Doser, Michael; Pérez, Patrice

    2018-03-01

    Why does our universe consist purely of matter, even though the same amount of antimatter and matter should have been produced at the moment of the Big Bang 13.8 billion years ago? One of the most potentially fruitful approaches to address the mystery is to study the properties of antihydrogen and antiprotons. Because they are both stable, we can in principle make measurement precision as high as we need to see differences between these antimatter systems and their matter counterparts, i.e. hydrogen and protons. This is the goal of cold antihydrogen research. To study a fundamental symmetry-charge, parity, and time reversal (CPT) symmetry-which should lead to identical spectra in hydrogen and antihydrogen, as well as the weak equivalence principle (WEP), cold antihydrogen research seeks any discrepancies between matter and antimatter, which might also offer clues to the missing antimatter mystery. Precision tests of CPT have already been carried out in other systems, but antihydrogen spectroscopy offers the hope of reaching even higher sensitivity to violations of CPT. Meanwhile, utilizing the Earth and antihydrogen atoms as an experimental system, the WEP predicts a gravitational interaction between matter and antimatter that is identical to that between any two matter objects. The WEP has been tested to very high precision for a range of material compositions, but no such precision test using antimatter has yet been carried out, offering hope of a telltale inconsistency between matter and antimatter. In this Discovery book, we invite you to visit the frontiers of cold antimatter research, focusing on new technologies to form beams of antihydrogen atoms and antihydrogen ions, and new ways of interrogating the properties of antimatter.

  10. Beam Techniques - Beam Control and Manipulation

    International Nuclear Information System (INIS)

    Minty, Michiko G

    2003-01-01

    We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization

  11. Beam Techniques - Beam Control and Manipulation

    Energy Technology Data Exchange (ETDEWEB)

    Minty, Michiko G

    2003-04-24

    We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

  12. Literature in Focus Beta Beams: Neutrino Beams

    CERN Document Server

    2009-01-01

    By Mats Lindroos (CERN) and Mauro Mezzetto (INFN Padova, Italy) Imperial Press, 2009 The beta-beam concept for the generation of electron neutrino beams was first proposed by Piero Zucchelli in 2002. The idea created quite a stir, challenging the idea that intense neutrino beams only could be produced from the decay of pions or muons in classical neutrino beams facilities or in future neutrino factories. The concept initially struggled to make an impact but the hard work by many machine physicists, phenomenologists and theoreticians over the last five years has won the beta-beam a well-earned position as one of the frontrunners for a possible future world laboratory for high intensity neutrino oscillation physics. This is the first complete monograph on the beta-beam concept. The book describes both technical aspects and experimental aspects of the beta-beam, providing students and scientists with an insight into the possibilities o...

  13. Production and study of therapeutic proton beams from modernized phasotron at the Laboratory of Nuclear Problems JINR

    International Nuclear Information System (INIS)

    Abazov, V.M.; Gustov, S.A.; Zorin, V.P.; Kutuzov, S.A.; Mirokhin, I.V.; Mitsyn, G.V.; Molokanov, A.G.; Savchenko, O.V.; Filimonov, A.V.

    1986-01-01

    The first results on shaping and transport of therapeutic proton beams of the JINR phasotron are presented. To provide the flat-topped depth-dose distributions with steep back slope, the method of shaping the beam with a necessary energy spectrum from a non-monoenergetic beam is used. Extension of the flat-top of the depth-dose distribution is 4.7 g/cm 2 for the 200 MeV beam energy

  14. The exchangeability of shape

    Directory of Open Access Journals (Sweden)

    Kaba Dramane

    2010-10-01

    Full Text Available Abstract Background Landmark based geometric morphometrics (GM allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes.

  15. Shape memory materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Compared with piezoelectric ceramics and magnetostrictive materials, the shape memory materials possess larger recoverable strain and recovery stress but slower response to external field. It is expected that the magneto-shape memory materials may develop considerable strain as well as rapid and precise shape control. Pseudoelasticity and shape memory effect (SME) resulted from martensitic transformation and its reverse transformation in shape memory materials were generally described. The requirements of appearing the shape memory effect in materials and the criteria for thermoelastic martensitic transformation were given. Some aspects concerning characteristics of martensitic transformation, and factors affecting SME in Ni-Ti, Cu-Zn-Al and Fe-Mn-Si based alloys as well as ZrO2 containing ceramics were briefly reviewed. Thermodynamic calculation of Ms temperature as function of grain size and parent ordering in Cu-Zn-Al was presented. The works on prediction of Ms in Fe-Mn-Si based alloys and in ZrO2-CeO2 were mentioned. Magnetic shape memory materials were briefly introduced.

  16. Generation of programmable temporal pulse shape and applications in micromachining

    Science.gov (United States)

    Peng, X.; Jordens, B.; Hooper, A.; Baird, B. W.; Ren, W.; Xu, L.; Sun, L.

    2009-02-01

    In this paper we presented a pulse shaping technique on regular solid-state lasers and the application in semiconductor micromachining. With a conventional Q-switched laser, all of the parameters can be adjusted over only limited ranges, especially the pulse width and pulse shape. However, some laser link processes using traditional laser pulses with pulse widths of a few nanoseconds to a few tens of nanoseconds tend to over-crater in thicker overlying passivation layers and thereby cause IC reliability problems. Use of a laser pulse with a special shape and a fast leading edge, such as tailored pulse, is one technique for controlling link processing. The pulse shaping technique is based on light-loop controlled optical modulation to shape conventional Q-switched solid-state lasers. One advantage of the pulse shaping technique is to provide a tailored pulse shape that can be programmed to have more than one amplitude value. Moreover, it has the capability of providing programmable tailored pulse shapes with discrete amplitude and time duration components. In addition, it provides fast rising and fall time of each pulse at fairly high repetition rate at 355nm with good beam quality. The regular-to-shaped efficiency is up to 50%. We conclude with a discussion of current results for laser processing of semiconductor memory link structures using programmable temporal pulse shapes. The processing experiments showed promising results with shaped pulse.

  17. Mechanically reinforced glass beams

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes

    2007-01-01

    laminated float glass beam is constructed and tested in four-point bending. The beam consist of 4 layers of glass laminated together with a slack steel band glued onto the bottom face of the beam. The glass parts of the tested beams are \\SI{1700}{mm} long and \\SI{100}{mm} high, and the total width of one...

  18. Telecommunication using muon beams

    International Nuclear Information System (INIS)

    Arnold, R.C.

    1976-01-01

    Telecommunication is effected by generating a beam of mu mesons or muons, varying a property of the beam at a modulating rate to generate a modulated beam of muons, and detecting the information in the modulated beam at a remote location

  19. Molecular-beam scattering

    International Nuclear Information System (INIS)

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N 2 from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl → NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2 2 P/sub 3/2/) and Na(3 2 P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included

  20. Characterisation of flattening filter free (FFF) beam properties for initial beam set-up and routine QA, independent of flattened beams

    Science.gov (United States)

    Paynter, D.; Weston, S. J.; Cosgrove, V. P.; Thwaites, D. I.

    2018-01-01

    Flattening filter free (FFF) beams have reached widespread use for clinical treatment deliveries. The usual methods for FFF beam characterisation for their quality assurance (QA) require the use of associated conventional flattened beams (cFF). Methods for QA of FFF without the need to use associated cFF beams are presented and evaluated against current methods for both FFF and cFF beams. Inflection point normalisation is evaluated against conventional methods for the determination of field size and penumbra for field sizes from 3 cm  ×  3 cm to 40 cm  ×  40cm at depths from dmax to 20 cm in water for matched and unmatched FFF beams and for cFF beams. A method for measuring symmetry in the cross plane direction is suggested and evaluated as FFF beams are insensitive to symmetry changes in this direction. Methods for characterising beam energy are evaluated and the impact of beam energy on profile shape compared to that of cFF beams. In-plane symmetry can be measured, as can cFF beams, using observed changes in profile, whereas cross-plane symmetry can be measured by acquiring profiles at collimator angles 0 and 180. Beam energy and ‘unflatness’ can be measured as with cFF beams from observed shifts in profile with changing beam energy. Normalising the inflection points of FFF beams to 55% results in an equivalent penumbra and field size measurement within 0.5 mm of conventional methods with the exception of 40 cm  ×  40 cm fields at a depth of 20 cm. New proposed methods are presented that make it possible to independently carry out set up and QA measurements on beam energy, flatness, symmetry and field size of an FFF beam without the need to reference to an equivalent flattened beam of the same energy. The methods proposed can also be used to carry out this QA for flattened beams, resulting in universal definitions and methods for MV beams. This is presented for beams produced by an Elekta linear accelerator, but is

  1. Fundamental study on laser manipulation of contamination particles with determining shape, size and species

    International Nuclear Information System (INIS)

    Shimizu, Isao; Fujii, Taketsugu

    1995-01-01

    It has been desired to eliminate or collect the contamination particles of radioisotope in each sort of species or shape and size non-invasively. The shape and size of particle can be determined from the shape and distribution of diffraction pattern of particle in the parallel laser beam, the species of particle can be discriminated by the fluorescence from resonance of laser beam, or by the laser Raman scattering, and the particle suspended in the air or falling down in a vacuum can be levitated against the gravity and trapped by the radiation force and the trapping force of the focussed laser beam in the atmosphere or in a vacuum. For the purpose of the non-invasive manipulation of contamination particles, the laser manipulation technique, image processing technique with Multiplexed Matched Spatial Filter and the determination technique of laser Raman scattering or fluorescence from resonance of laser light were combined in the experiments. The shape, size and species of particles trapped in the focal plane of focused Ar laser beam can be determined simultaneously and instantaneously from the shape and intensity distributions of diffraction patterns of the particles in the irradiation of parallel coherent beam of He-Ne laser, and fluorescence from the resonance of YAG laser beam with variable wave length. In this research, a new technique is proposed to manipulate non-invasively the contamination particles determined with the shape, size and species in the atmosphere or in a vacuum, by laser beam. (author)

  2. Shape Coexistence In Light Krypton Isotopes

    International Nuclear Information System (INIS)

    Clement, E.; Goergen, A.; Bouchez, E.; Chatillon, A.; Korten, W.; Le Coz, Y.; Theisen, Ch.; Huerstel, A.; Lucas, R.; Wilson, J.N.; Andreoiu, C.; Butler, P.; Herzberg, R.-D.; Iwanicki, J.; Jenkins, D.; Jones, G.; Becker, F.; Gerl, J.; Blank, B.; Hannachi, F.

    2005-01-01

    Shape coexistence in the light krypton isotopes was studied in a series of experiments at GANIL using various experimental techniques. A new low-lying 0+ state, a so-called shape isomer, was found in delayed conversion-electron spectroscopy after fragmentation reactions. The systematics of such low-lying 0+ states suggests that the ground states of the isotopes 78Kr and 76Kr have prolate deformation, while states with prolate and oblate shape are practically degenerate and strongly mixed in 74Kr, and that the oblate configuration becomes the ground state in 72Kr. This scenario was tested in experiments performing low-energy Coulomb excitation of radioactive 76Kr and 74Kr beams from the SPIRAL facility. Both transitional and diagonal electromagnetic matrix elements were extracted from the observed γ-ray yields. The results find the prolate shape for the ground-state bands in 76Kr and 74Kr and an oblate deformation for the excited 2 2 + state in 74Kr, confirming the proposed scenario of shape coexistence

  3. Safe LHC beam commissioning

    International Nuclear Information System (INIS)

    Uythoven, J.; Schmidt, R.

    2007-01-01

    Due to the large amount of energy stored in magnets and beams, safety operation of the LHC is essential. The commissioning of the LHC machine protection system will be an integral part of the general LHC commissioning program. A brief overview of the LHC Machine Protection System will be given, identifying the main components: the Beam Interlock System, the Beam Dumping System, the Collimation System, the Beam Loss Monitoring System and the Quench Protection System. An outline is given of the commissioning strategy of these systems during the different commissioning phases of the LHC: without beam, injection and the different phases with stored beam depending on beam intensity and energy. (author)

  4. LANSCE beam current limiter

    International Nuclear Information System (INIS)

    Gallegos, F.R.

    1996-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described

  5. SU-E-T-353: Decoding the Beam Complexity in Intensity-Modulated Radiation Therapy Plans

    International Nuclear Information System (INIS)

    Du, W; Cho, S; Zhang, X; Hoffman, K; Kudchadker, R

    2014-01-01

    Purpose: Modern IMRT relies on computers to generate treatment plans of varied complexity. A highly complex treatment plan may use a large number of small and irregular beam apertures in order to achieve high dose conformity. However, excessive beam complexity can increase dosimetric uncertainty, prolong treatment time, and increase susceptibility to target or organ motion. In this study we sought to develop metrics to assess the complexity of IMRT beams and plans. Methods: Based the information of leaf positions and MU for each beam segment, we calculated the following beam complexity metrics: aperture area, shape irregularity, and beam modulation. Then these beam complexity metrics were averaged to obtain the corresponding plan complexity metrics, using the beam MUs as weighting factors. We evaluated and compared the beam and plan complexity scores for 65 IMRT plans from 3 sites (prostate, head and neck, and spine). We also studied how the plan complexity scores were affected by adjusting inverse planning parameters. Results: For prostate IMRT, the lateral beams had large MUs and smaller shape irregularity, while the anterior or posterior beams had larger modulation values. On average, the prostate IMRT plans had the smallest shape irregularity and beam modulation; the HN IMRT plans had the largest aperture area, shape irregularity, and beam modulation; and the spine stereotactic IMRT plans often had small aperture area, which may be associated with relatively large discrepancies between calculated and measures doses. The plan complexity increased as the number of optimization iterations and the number of beam segments increased and as the minimum segment area decreased. Conclusion: Complexity of IMRT beams and plans were quantified in terms of aperture area, shape irregularity and beam modulation. The complexity metrics varied among IMRT plans for different disease sites and were affected when the planning parameters were adjusted

  6. Performance of positive ion based high power ion source of EAST neutral beam injector

    International Nuclear Information System (INIS)

    Hu, Chundong; Xie, Yahong; Xie, Yuanlai; Liu, Sheng; Xu, Yongjian; Liang, Lizhen; Jiang, Caichao; Li, Jun; Liu, Zhimin

    2016-01-01

    The positive ion based source with a hot cathode based arc chamber and a tetrode accelerator was employed for a neutral beam injector on the experimental advanced superconducting tokamak (EAST). Four ion sources were developed and each ion source has produced 4 MW @ 80 keV hydrogen beam on the test bed. 100 s long pulse operation with modulated beam has also been tested on the test bed. The accelerator was upgraded from circular shaped to diamond shaped in the latest two ion sources. In the latest campaign of EAST experiment, four ion sources injected more than 4 MW deuterium beam with beam energy of 60 keV into EAST

  7. Electron beam extraction from a HVPES

    Energy Technology Data Exchange (ETDEWEB)

    Marghitu, S; Cramariuc, R [Accelerators Laboratory, Institute of Physics and Technology for Radiation Devices, PO Box MG-06, R-76900 Bucharest (Romania); Nicolescu, I; Niculescu, M [Institute of Research and Design for Electrical Engineering, ICPE - Electrostatica, Splaiul Unirii 313, Sect. 3, R-74204 Bucharest (Romania)

    1997-12-31

    The results of the research concerning the extraction system of the fast electrons from a cold cathode high voltage glow discharge plasma electron source (HVPES) are presented. For using the electron beam in a more flexible way, that is changing the shape of the minimum cross-section, (or beam cross-over), of the beam in a sample S frontal plane, without perturbing the discharge parameters, some modifications to a reference internal geometry were tested. Finally, a geometry was found in which the discharge volume may be separated in two parts, one, `a discharge space`, filled with plasma and fast electrons and another, `working space`, occupied specially by the fast electron beam. In this new geometry the electrical discharge parameters, I{sub d} - discharge current, U{sub d} - discharge voltage, were the same as for the reference geometry. (authors) 5 refs., 4 figs., 3 tabs.

  8. Electron beam extraction from a HVPES

    International Nuclear Information System (INIS)

    Marghitu, S.; Cramariuc, R.; Nicolescu, I.; Niculescu, M.

    1996-01-01

    The results of the research concerning the extraction system of the fast electrons from a cold cathode high voltage glow discharge plasma electron source (HVPES) are presented. For using the electron beam in a more flexible way, that is changing the shape of the minimum cross-section, (or beam cross-over), of the beam in a sample S frontal plane, without perturbing the discharge parameters, some modifications to a reference internal geometry were tested. Finally, a geometry was found in which the discharge volume may be separated in two parts, one, 'a discharge space', filled with plasma and fast electrons and another, 'working space', occupied specially by the fast electron beam. In this new geometry the electrical discharge parameters, I d - discharge current, U d - discharge voltage, were the same as for the reference geometry. (authors)

  9. DESIGN of MICRO CANTILEVER BEAM for VAPOUR DETECTION USING COMSOL MULTI PHYSICS SOFTWARE

    OpenAIRE

    Sivacoumar R; Parvathy JM; Pratishtha Deep

    2015-01-01

    This paper gives an overview of micro cantilever beam of various shapes and materials for vapour detection. The design of micro cantilever beam, analysis and simulation is done for each shape. The simulation is done using COMSOL Multi physics software using structural mechanics and chemical module. The simulation results of applied force and resulting Eigen frequencies will be analyzed for different beam structures. The vapour analysis is done using flow cell that consists of chemical pill...

  10. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  11. Ion beam diagnosis

    International Nuclear Information System (INIS)

    Strehl, P.

    1994-04-01

    This report is an introduction to ion beam diagnosis. After a short description of the most important ion beam parameters measurements of the beam current by means of Faraday cups, calorimetry, and beam current transformers and measurements of the beam profile by means of viewing screens, profile grids and scanning devices, and residual gas ionization monitors are described. Finally measurements in the transverse and longitudinal phase space are considered. (HSI)

  12. In-beam PET at clinical proton beams with pile-up rejection

    Energy Technology Data Exchange (ETDEWEB)

    Helmbrecht, Stephan; Fiedler, Fine; Iltzsche, Marc [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Radiation Physics; Enghardt, Wolfgang [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Radiation Physics; OncoRay - National Center for Radiation Research in Oncology, Dresden (Germany); Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Radiooncology; German Cancer Research Center (DKFZ), Heidelberg (Germany); German Cancer Consortium (DKTK), Dresden (Germany); Pausch, Guntram [OncoRay - National Center for Radiation Research in Oncology, Dresden (Germany); Tintori, Carlo [CAEN S.p.A., Viareggio (Italy); Kormoll, Thomas [OncoRay - National Center for Radiation Research in Oncology, Dresden (Germany); Technische Univ. Dresden (Germany). AG Radiation Physics

    2017-10-01

    Positron emission tomography (PET) is a means of imaging the β{sup +}-activity produced by the radiation field in ion beam therapy and therefore for treatment verification. Prompt γ-rays that are emitted during beam application challenge the detectors and electronics of PET systems, since those are designed for low and medium count rates. Typical PET detectors operated according to a modified Anger principle suffer from multiple events at high rates. Therefore, in-beam PET systems using such detectors rely on a synchronization of beam status and measurement to reject deteriorated data. In this work, a method for pile-up rejection is applied to conventional Anger logic block detectors. It allows for an in-beam data acquisition without further synchronization. Though cyclotrons produce a continuous wave beam, the radiation field shaping technique introduces breaks in the application. Time regimes mimicking synchrotrons as well as cyclotron based ones using double-scattering or pencil beam scanning field shaping at dose rates of 0.5, 1.0 and 2.0 Gy/min were investigated. Two types of inhomogeneous phantoms were imaged. The first one simulates cavity structures, the other one mimics a static lung irradiation. It could be shown that, depending on the dose rate and the beam time structure, in-beam measurement including a few seconds decay time only, yield images which revealed all inhomogeneities in the phantoms. This technique can be the basis for the development of an in-beam PET system with traditional detectors and off-the-shelf electronics.

  13. Magnetic shape memory behaviour

    International Nuclear Information System (INIS)

    Brown, P.J.; Gandy, A.P.; Ishida, K.; Kainuma, R.; Kanomata, T.; Matsumoto, M.; Morito, H.; Neumann, K.-U.; Oikawa, K.; Ouladdiaf, B.; Ziebeck, K.R.A.

    2007-01-01

    Materials that can be transformed at one temperature T F , then cooled to a lower temperature T M and plastically deformed and on heating to T F regain their original shape are currently receiving considerable attention. In recovering their shape the alloys can produce a displacement or a force, or a combination of the two. Such behaviour is known as the shape memory effect and usually takes place by change of temperature or applied stress. For many applications the transformation is not sufficiently rapid or a change in temperature/pressure not appropriate. As a result, considerable effort is being made to find a ferromagnetic system in which the effect can be controlled by an applied magnetic field. The results of recent experiments on ferromagnetic shape memory compounds aimed at understanding the underlying mechanism will be reviewed

  14. Shaping the ROTC Cohort

    National Research Council Canada - National Science Library

    Rittenhouse, Wiley P; Kwinn, Jr, Michael J

    2005-01-01

    ...) - to meet the future needs of the Army for commissioned officers. It is designed to shape each cohort to meet the Army's specific needs in terms of component, academic disciplines, race/ethnic makeup goals, gender, and targeted missions...

  15. Email shape analysis

    OpenAIRE

    Sroufe, Paul; Phithakkitnukoon, Santi; Dantu, Ram; Cangussu, João

    2010-01-01

    Email has become an integral part of everyday life. Without a second thought we receive bills, bank statements, and sales promotions all to our inbox. Each email has hidden features that can be extracted. In this paper, we present a new mechanism to characterize an email without using content or context called Email Shape Analysis. We explore the applications of the email shape by carrying out a case study; botnet detection and two possible applications: spam filtering, and social-context bas...

  16. STEREOLOGICAL ANALYSIS OF SHAPE

    Directory of Open Access Journals (Sweden)

    Asger Hobolth

    2011-05-01

    Full Text Available This paper concerns the problem of making stereological inference about the shape variability in a population of spatial particles. Under rotational invariance the shape variability can be estimated from central planar sections through the particles. A simple, but flexible, parametric model for rotation invariant spatial particles is suggested. It is shown how the parameters of the model can be estimated from observations on central sections. The corresponding model for planar particles is also discussed in some detail.

  17. Universality of fragment shapes.

    Science.gov (United States)

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-03-16

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

  18. Testing optimization sequence for the beam port facility of PSBR

    International Nuclear Information System (INIS)

    Bekar, K.B.; Azmy, Y.Y.; Unlu, K.

    2005-01-01

    We present preliminary testing results of the modular code package prepared for the size and shape optimization of the beam tube device of the beam port facility at the Penn State Breazeale Reactor (PSBR). In the test cases, using the Min-max algorithm as an optimizer and multidimensional, neutral particle transport code TORT as a transport solver in the physics calculation, we optimize the shape of the D 2 O moderator of the beam tube device. We illustrate the modular nature of the optimization package, validation tests of the physics model, and preliminary optimization calculation via the whole code package. Results obtained so far indicate the drum-shaped D 2 O moderator tank is over-designed in size and does not possess the almost hemi-spherical optimal shape computed by our new package. (authors)

  19. Reconstruction of IP Beam Parameters at the ILC from Beamstraahlung

    CERN Document Server

    White, Glen

    2005-01-01

    The luminosity performance of the ILC will be very sensitive to the parameters of the colliding bunches. Only some of these parameters can be measured using planned instrumentation. This analysis aims to access some of the colliding beam parameters not available by other means and to improve on the resolution of those that are. GUINEA-PIG is used to simulate the beam-beam interactions and produce beamstrahlung radiation (e+/e- pairs and photons). These are tracked to a simulation of the low-angle Beam Calorimeter and a photon detector and event shapes are produced. A Taylor map is produced to transform from the event shapes to the simulated beam parameters. This paper reports on the progress of this analysis, examining the usefulness of the proposed fitting technique.

  20. Pulling cylindrical particles using a soft-nonparaxial tractor beam

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Ding, Weiqiang; Wang, Maoyan

    2017-01-01

    In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate the nonparaxi......In order to pull objects towards the light source a single tractor beam inevitably needs to be strongly nonparaxial. This stringent requirement makes such a tractor beam somewhat hypothetical. Here we reveal that the cylindrical shape of dielectric particles can effectively mitigate...... the nonparaxiality requirements, reducing the incidence angle of the partial plane waves of the light beam down to 45 degrees and even to 30 degrees for respectively dipole and dipole-quadrupole objects. The optical pulling force attributed to the interaction of magnetic dipole and magnetic quadrupole moments...... and sorting of targeted particles....

  1. Shapes of interacting RNA complexes

    DEFF Research Database (Denmark)

    Fu, Benjamin Mingming; Reidys, Christian

    2014-01-01

    Shapes of interacting RNA complexes are studied using a filtration via their topological genus. A shape of an RNA complex is obtained by (iteratively) collapsing stacks and eliminating hairpin loops.This shape-projection preserves the topological core of the RNA complex and for fixed topological...... genus there are only finitely many such shapes. Our main result is a new bijection that relates the shapes of RNA complexes with shapes of RNA structures. This allows to compute the shape polynomial of RNA complexes via the shape polynomial of RNA structures. We furthermore present a linear time uniform...... sampling algorithm for shapes of RNA complexes of fixed topological genus....

  2. Modular beam diagnostics instrument design for Cyclotrons

    International Nuclear Information System (INIS)

    Chaddha, N.; Bhole, R.B.; Sahoo, S.; Nandy, P.P.; Pal, S.

    2012-01-01

    The Cyclotrons at VECC, Kolkata i.e. Room Temperature Cyclotron (RTC) and Superconducting Cyclotron (SCC) comprise of internal and external Beam Diagnostic systems. These systems provide the beam developer with position, intensity, beam profile, a visual impression of the size and shape of ion beam, and operational control over diagnostic components like 3-finger probe, Beam Viewer probe, Deflector probe, Faraday cup, X-Y slit, Beam viewer etc. Automation of these components was initially done using customised modules for individual sub-system. An expansion of this facility and various levels of complexity demand modular design to cater easy modification and upgradation. The overall requirements are analysed and modular cards are developed based on basic functionalities like valve operation, probe/slit/viewer control, position read-out, Interlock, aperture control of beam line and communication. A 32-bit Advanced RISC Machine (ARM) based card with embedded EPICS is chosen as the master controller and FPGA/microcontroller is used for functional modules. The paper gives a comprehensive description of all modules and their integration with the control system. (author)

  3. Cell sorting using efficient light shaping approaches

    DEFF Research Database (Denmark)

    Banas, Andrew; Palima, Darwin; Villangca, Mark Jayson

    2016-01-01

    distributions aimed at the positions of the detected cells. Furthermore, the beam shaping freedom provided by GPC can allow optimizations in the beam’s propagation and its interaction with the catapulted cells. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading...... is gentler, less invasive and more economical compared to conventional FACS systems. As cells are less responsive to plastic or glass beads commonly used in the optical manipulation literature, and since laser safety would be an issue in clinical use, we develop efficient approaches in utilizing lasers...... and light modulation devices. The Generalized Phase Contrast (GPC) method that can be used for efficiently illuminating spatial light modulators or creating well-defined contiguous optical traps is supplemented by diffractive techniques capable of integrating the available light and creating 2D or 3D beam...

  4. Beam diagnostics for low energy beams

    Directory of Open Access Journals (Sweden)

    J. Harasimowicz

    2012-12-01

    Full Text Available Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralow-energy storage ring (USR at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

  5. Polarization coupling of vector Bessel–Gaussian beams

    International Nuclear Information System (INIS)

    Takeuchi, Ryushi; Kozawa, Yuichi; Sato, Shunichi

    2013-01-01

    We report polarization coupling of radial and azimuthal electric field components of a vector light beam as predicted by the fact that the vector Helmholtz equation is expressed as coupled differential equations in cylindrical coordinates. To clearly observe the polarization variation of a beam as it propagates, higher order transverse modes of a vector Bessel–Gaussian beam were generated by a gain distribution modulation technique, which created a narrow ring-shaped gain region in a Nd:YVO 4 crystal. The polarization coupling was confirmed by the observation that the major polarization component of a vector Bessel–Gaussian beam alternates between radial and azimuthal components along with the propagation. (paper)

  6. Recovery of CTF beam signals from a strong wakefield background

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Y [TRIUMF, Vancouver, BC (Canada); Schulte, E [European Organization for Nuclear Research, Geneva (Switzerland); Ekeloef, T [Uppsala Univ. (Sweden)

    1995-06-01

    The beam monitor for the CERN Linear Collider Test Facility (CTF) has to work not only with very short pulses (350 ps FWHM) at a spacing of 330 ps, but also in a strong wakefield background. A cone-shaped button pickup electrode has been designed and constructed for use with CTF beams and tests have been made using a real time analogue Gaussian filter to recover the beam signals from the strong wakefield signals. As a comparison to the analogue filter, a study has been made to process the data off-line and extract the beam signals using digital filtering based on the wavelet concept. (author). 3 refs., 7 figs.

  7. A rugby-shaped cavity for the LMJ

    International Nuclear Information System (INIS)

    Vandenboomgaerde, M.; Bastian, J.; Casner, A.; Galmiche, D.; Jadaud, J.P.; Lafitte, S.; Liberatore, S.; Malinie, G.; Philippe, F.

    2008-01-01

    Numerical studies show that a rugby-shaped hohlraum for indirect drive laser ignition has some advantages: it allows a better symmetry for the X-ray irradiation of the central target and it required less laser power. Rugby-shaped cavities have been tested successfully at the Omega facility. The energetic advantage is all the more important as the cavity is bigger. Simulations have shown that a rugby-shaped hohlraum plus adequate materials for the intern wall plus an optimization of the central target could open the way to an ignition with only 160 laser beams at the LMJ (Megajoule Laser) facility. (A.C.)

  8. Shape changing collisions of optical solitons, universal logic gates ...

    Indian Academy of Sciences (India)

    communication via optical fibers [1] and the observation of self trapping of optical beams ... From a theoretical point of view, in the context of intense optical pulse ...... play a pivotal role in the shape changing collision process. ...... [1] See for example, several articles in the Focus Issue on “Optical Solitons - Perspectives and.

  9. Spatial Resolution of a Wedge Shaped MSGC Module

    CERN Document Server

    Bachmann, Sebastian

    1997-01-01

    A banana shaped closed design MSGC detector module was tested together with silicon detectors and other MSGCs in a 100 GeV muon beam. Despite of an undesirable geometry of the test setup, a spatial resolution below 40 micron m was reached. The efficiency of the module, defined by track reconstruction, shows to be 95,6 percent

  10. Customized shaping of vibration modes by acoustic metamaterial synthesis

    Science.gov (United States)

    Xu, Jiawen; Li, Shilong; Tang, J.

    2018-04-01

    Acoustic metamaterials have attractive potential in elastic wave guiding and attenuation over specific frequency ranges. The vast majority of related investigations are on transient waves. In this research we focus on stationary wave manipulation, i.e., shaping of vibration modes. Periodically arranged piezoelectric transducers shunted with inductive circuits are integrated to a beam structure to form a finite-length metamaterial beam. We demonstrate for the first time that, under a given operating frequency of interest, we can facilitate a metamaterial design such that this frequency becomes a natural frequency of the integrated system. Moreover, the vibration mode corresponding to this natural frequency can be customized and shaped to realize tailored/localized response distribution. This is fundamentally different from previous practices of utilizing geometry modification and/or feedback control to achieve mode tailoring. The metamaterial design is built upon the combinatorial effects of the bandgap feature and the effective resonant cavity feature, both attributed to the dynamic characteristics of the metamaterial beam. Analytical investigations based on unit-cell dynamics and modal analysis of the metamaterial beam are presented to reveal the underlying mechanism. Case illustrations are validated by finite element analyses. Owing to the online tunability of circuitry integrated, the proposed mode shaping technique can be online adjusted to fit specific requirements. The customized shaping of vibration modes by acoustic metamaterial synthesis has potential applications in vibration suppression, sensing enhancement and energy harvesting.

  11. Prediction on flexural strength of encased composite beam with cold-formed steel section

    Science.gov (United States)

    Khadavi, Tahir, M. M.

    2017-11-01

    A flexural strength of composite beam designed as boxed shaped section comprised of lipped C-channel of cold-formed steel (CFS) facing each other with reinforcement bars is proposed in this paper. The boxed shaped is kept restrained in position by a profiled metal decking installed on top of the beam to form a slab system. This profiled decking slab is cast by using self-compacting concrete where the concrete is in compression when load is applied to the beam. Reinforcement bars are used as shear connector between slab and CFS as beam. A numerical analysis method proposed by EC4 is used to predict the flexural strength of the proposed composite beam. It was assumed that elasto-plastic behaviour is developed in the cross -sectional of the proposed beam. The calculated predicted flexural strength of the proposed beam shows reasonable flexural strength for cold-formed composite beam.

  12. Studies of the beam-beam interaction for the LHC

    International Nuclear Information System (INIS)

    Krishnagopal, S.; Furman, M.A.; Turner, W.C.

    1999-01-01

    The authors have used the beam-beam simulation code CBI to study the beam-beam interaction for the LHC. We find that for nominal LHC parameters, and assuming only one bunch per beam, there are no collective (coherent) beam-beam instabilities. We have investigated the effect of sweeping one of the beams around the other (a procedure that could be used as a diagnostic for head-on beam-beam collisions). We find that this does not cause any problems at the nominal current, though at higher currents there can be beam blow-up and collective beam motion. consequence of quadrupole collective effects

  13. Ion-optical studies for a range adaptation method in ion beam therapy using a static wedge degrader combined with magnetic beam deflection

    International Nuclear Information System (INIS)

    Chaudhri, Naved; Saito, Nami; Bert, Christoph; Franczak, Bernhard; Steidl, Peter; Durante, Marco; Schardt, Dieter; Rietzel, Eike

    2010-01-01

    Fast radiological range adaptation of the ion beam is essential when target motion is mitigated by beam tracking using scanned ion beams for dose delivery. Electromagnetically controlled deflection of a well-focused ion beam on a small static wedge degrader positioned between two dipole magnets, inside the beam delivery system, has been considered as a fast range adaptation method. The principle of the range adaptation method was tested in experiments and Monte Carlo simulations for the therapy beam line at the GSI Helmholtz Centre for Heavy Ions Research. Based on the simulations, ion optical settings of beam deflection and realignment of the adapted beam were experimentally applied to the beam line, and additional tuning was manually performed. Different degrader shapes were employed for the energy adaptation. Measured and simulated beam profiles, i.e. lateral distribution and range in water at isocentre, were analysed and compared with the therapy beam values for beam scanning. Deflected beam positions of up to ±28 mm on degrader were performed which resulted in a range adaptation of up to ±15 mm water equivalence (WE). The maximum deviation between the measured adapted range from the nominal range adaptation was below 0.4 mm WE. In experiments, the width of the adapted beam at the isocentre was adjustable between 5 and 11 mm full width at half maximum. The results demonstrate the feasibility/proof of the proposed range adaptation method for beam tracking from the beam quality point of view.

  14. Low current beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saint, A; Laird, J S; Bardos, R A; Legge, G J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T; Sekiguchi, H [Electrotechnical Laboratory, Tsukuba (Japan).

    1994-12-31

    Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

  15. Low current beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saint, A.; Laird, J.S.; Bardos, R.A.; Legge, G.J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T.; Sekiguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan).

    1993-12-31

    Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

  16. SHAPE selection (SHAPES) enrich for RNA structure signal in SHAPE sequencing-based probing data

    DEFF Research Database (Denmark)

    Poulsen, Line Dahl; Kielpinski, Lukasz Jan; Salama, Sofie R

    2015-01-01

    transcriptase. Here, we introduce a SHAPE Selection (SHAPES) reagent, N-propanone isatoic anhydride (NPIA), which retains the ability of SHAPE reagents to accurately probe RNA structure, but also allows covalent coupling between the SHAPES reagent and a biotin molecule. We demonstrate that SHAPES...

  17. Design of shape memory alloy (SMA) actuators

    CERN Document Server

    Rao, Ashwin; Reddy, J N

    2015-01-01

    This short monograph presents an analysis and design methodology for shape memory alloy (SMA) components such as wires, beams, and springs for different applications. The solid-solid, diffusionless phase transformations in thermally responsive SMA allows them to demonstrate unique characteristics like superelasticity and shape memory effects. The combined sensing and actuating capabilities of such materials allows them to provide a system level response by combining multiple functions in a single material system. In SMA, the combined mechanical and thermal loading effects influence the functionality of such materials. The aim of this book is to make the analysis of these materials accessible to designers by developing a "strength of materials" approach to the analysis and design of such SMA components inspired from their various applications with a review of various factors influencing the design process for such materials.

  18. Shape memory polymer medical device

    Science.gov (United States)

    Maitland, Duncan [Pleasant Hill, CA; Benett, William J [Livermore, CA; Bearinger, Jane P [Livermore, CA; Wilson, Thomas S [San Leandro, CA; Small, IV, Ward; Schumann, Daniel L [Concord, CA; Jensen, Wayne A [Livermore, CA; Ortega, Jason M [Pacifica, CA; Marion, III, John E.; Loge, Jeffrey M [Stockton, CA

    2010-06-29

    A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.

  19. Time domain simulations of beam-loading

    International Nuclear Information System (INIS)

    Koscielniak, S.

    1989-09-01

    We present the results of computer simulations of high current beam loading in a proton storage ring. The model integrates the differential equation for gap voltage, and iterates the difference equations for particle longitudinal motion. The effects of cavity fields on the bunch shape and of the fundamental component of the beam on the cavity are treated in a self-consistent manner. The simulation model is applied to verify the dipole-quadrupole hybrid Robinson instability criterion, which differs from the dipole-mode criterion

  20. Ion-beam nanopatterning: experimental results with chemically-assisted beam

    Science.gov (United States)

    Pochon, Sebastien C. R.

    2018-03-01

    The need for forming gratings (for example used in VR headsets) in materials such as SiO2 has seen a recent surge in the use of Ion beam etching techniques. However, when using an argon-only beam, the selectivity is limited as it is a physical process. Typically, gases such as CHF3, SF6, O2 and Cl2 can be added to argon in order to increase selectivity; depending on where the gas is injected, the process is known as Reactive Ion Beam Etching (RIBE) or Chemically Assisted Ion Beam Etching (CAIBE). The substrate holder can rotate in order to provide an axisymmetric etch rate profile. It can also be tilted over a range of angles to the beam direction. This enables control over the sidewall profile as well as radial uniformity optimisation. Ion beam directionality in conjunction with variable incident beam angle via platen angle setting enables profile control and feature shaping during nanopatterning. These hardware features unique to the Ion Beam etching methods can be used to create angled etch features. The CAIBE technique is also well suited to laser diode facet etch (for optoelectronic devices); these typically use III-V materials like InP. Here, we report on materials such as SiO2 etched without rotation and at a fixed platen angle allowing the formation of gratings and InP etched at a fixed angle with rotation allowing the formation of nanopillars and laser facets.

  1. Preparation of shaped bodies

    International Nuclear Information System (INIS)

    Sutcliffe, P.W.; Isaacs, J.W.; Lyon, C.E.

    1979-01-01

    A method for the preparation of a shaped body includes pressing a powder to give a 'green' shaped body, the powder having been made by comminuting a material prepared by means of a gelation process, the material prior to comminuting being of a selected physical configuration (e.g. spherical). Thus, a material prepared by means of a gelation process can be transported and handled in an environmentally desirable, substantially dust-free form (e.g. spherical particles) and then comminuted to produce a powder for pressing into e.g. a shaped nuclear fuel body (e.g. pellets of (70%U/30%Pu)O 2 ), which can be sintered. (author)

  2. Characterization of plasma parameters in shaped PBX-M discharges

    Science.gov (United States)

    England, A. C.; Bell, R. E.; Hirshman, S. P.; Kaita, R.; Kugel, H. W.; LeBlanc, B. L.; Lee, D. K.; Okabayashi, M.; Sun, Y.-C.; Takahashi, H.

    1997-09-01

    The Princeton Beta Experiment-Modification (PBX-M) was run both with elliptical and with bean-shaped plasmas during the 1992 and 1993 operating periods. Two deuterium-fed neutral beams were used for auxiliary heating, and during 1992 the average power was 0741-3335/39/9/008/img13. This will be referred to as the lower neutral-beam power (LNBP) period. As many as four deuterium-fed neutral beams were used during 1993, and the average power was 0741-3335/39/9/008/img14. This will be referred to as the medium neutral-beam power (MNBP) period. The neutron source strength, Sn, showed a scaling with injected power 0741-3335/39/9/008/img15, 0741-3335/39/9/008/img16 for both the LMBP and MNBP periods. A much wider range of shaping parameters was studied during the MNBP as compared with the LNBP period. A weak positive dependence on bean shaping was observed for the LNBP, and a stronger positive dependence on shaping was observed for MNBP, viz 0741-3335/39/9/008/img17. High values of Sn were obtained in bean-shaped plasmas for the highest values of 0741-3335/39/9/008/img18 at 0741-3335/39/9/008/img19 for the LNBP. For the MNBP the highest values of Sn and stored energy were obtained at 0741-3335/39/9/008/img19, and the highest values of 0741-3335/39/9/008/img18 were obtained at 0741-3335/39/9/008/img22. The achievement of high Sn is aided by high neutral-beam power, high toroidal field, strong shaping, high electron temperature, and broad profiles. The achievement of high 0741-3335/39/9/008/img18 is aided by low toroidal field, high density, less shaping, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img24. The achievement of high 0741-3335/39/9/008/img25 is aided by strong shaping, high density, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img26. Some comparisons with the previous higher neutral-beam (HNBP) period in 1989 are also made.

  3. Beam Dynamics and Beam Losses - Circular Machines

    CERN Document Server

    Kain, V

    2016-01-01

    A basic introduction to transverse and longitudinal beam dynamics as well as the most relevant beam loss mechanisms in circular machines will be presented in this lecture. This lecture is intended for physicists and engineers with little or no knowledge of this subject.

  4. Electron beam instabilities in gyrotron beam tunnels

    International Nuclear Information System (INIS)

    Pedrozzi, M.; Alberti, S.; Hogge, J.P.; Tran, M.Q.; Tran, T.M.

    1997-10-01

    Electron beam instabilities occurring in a gyrotron electron beam can induce an energy spread which might significantly deteriorate the gyrotron efficiency. Three types of instabilities are considered to explain the important discrepancy found between the theoretical and experimental efficiency in the case of quasi-optical gyrotrons (QOG): the electron cyclotron maser instability, the Bernstein instability and the Langmuir instability. The low magnetic field gradient in drift tubes of QOG makes that the electron cyclotron maser instability can develop in the drift tube at very low electron beam currents. Experimental measurements show that with a proper choice of absorbing structures in the beam tunnel, this instability can be suppressed. At high beam currents, the electrostatic Bernstein instability can induce a significant energy spread at the entrance of the interaction region. The induced energy spread scales approximately linearly with the electron beam density and for QOG one observes that the beam density is significantly higher than the beam density of an equivalent cylindrical cavity gyrotron. (author) figs., tabs., refs

  5. Vectorial analysis of the collimated beam of a small Gaussian source

    Science.gov (United States)

    Cao, Changqing; Wang, Ting; Zeng, Xiaodong; Feng, Zhejun; Zhang, Wenrui; Zhang, Xiaobing; Chen, Kun

    2018-03-01

    A vectorial analysis method to describe the collimated beam is proposed, the formulas of the intensity distribution and divergence angles represented in terms of Bessel functions are derived, and the propagation properties such as the vectorial structure of the collimated field and the shape of the beam spot are discussed in detail. Omitting the vectorial nature of the collimated beam can cause an error of 7.6% in determining the intensity distribution on the optical axis of the collimated beam.

  6. A novel design for electric field deflectometry on extended molecular beams

    International Nuclear Information System (INIS)

    Stefanov, André; Berninger, Martin; Arndt, Markus

    2008-01-01

    We discuss the optimal shape of a beam deflector with applications in electric susceptibility measurements on wide molecular beams. In contrast to the well-established 'two-wire' concept, which is optimized for beams with a small lateral extension, our design realizes a compact element that provides a high and homogeneous force field at moderate voltage for molecular beams with a large extension in the direction of deflection

  7. Social Shaping of Innovation

    DEFF Research Database (Denmark)

    Buur, Jacob; Mack, Alexandra

    - in particular in a large corporation? This workshop explores how innovation is socially shaped in organizations. Based on our experiences with practices around innovation and collaboration, we start from three proposition about the social shaping of innovation: • Ideas don't thrive as text (i.e. we need...... to consider other media) • Ideas need socialization (ideas are linked to people, we need to be careful about how we support the social innovation context) • Ideas are local (ideas spring out of a local contingency, we need to take care in how we like them to travel)....

  8. Covering folded shapes

    Directory of Open Access Journals (Sweden)

    Oswin Aichholzer

    2014-05-01

    Full Text Available Can folding a piece of paper flat make it larger? We explore whether a shape S must be scaled to cover a flat-folded copy of itself. We consider both single folds and arbitrary folds (continuous piecewise isometries \\(S\\to\\mathbb{R}^2\\. The underlying problem is motivated by computational origami, and is related to other covering and fixturing problems, such as Lebesgue's universal cover problem and force closure grasps. In addition to considering special shapes (squares, equilateral triangles, polygons and disks, we give upper and lower bounds on scale factors for single folds of convex objects and arbitrary folds of simply connected objects.

  9. Shape memory effect alloys

    International Nuclear Information System (INIS)

    Koshimizu, S.

    1992-01-01

    Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

  10. load-displacement and stability characteristics of tidn-walled beams

    African Journals Online (AJOL)

    the mast common of these are the I-shapes, Z-shapes, and the channels. While the I-shaped cross-section beams had received extensive coverage m experimental ... centroid C along the x-axis, while v, and w, represent the displacements of the shear center S in the y- and z- directions, respectively. Also, represents the.

  11. Successful Beam-Beam Tuneshift Compensation

    Energy Technology Data Exchange (ETDEWEB)

    Bishofberger, Kip Aaron [Univ. of California, Los Angeles, CA (United States)

    2005-01-01

    The performance of synchrotron colliders has been limited by the beam-beam limit, a maximum tuneshift that colliding bunches could sustain. Due to bunch-to-bunch tune variation and intra-bunch tune spread, larger tuneshifts produce severe emittance growth. Breaking through this constraint has been viewed as impossible for several decades. This dissertation introduces the physics of ultra-relativistic synchrotrons and low-energy electron beams, with emphasis placed on the limits of the Tevatron and the needs of a tuneshift-compensation device. A detailed analysis of the Tevatron Electron Lens (TEL) is given, comparing theoretical models to experimental data whenever possible. Finally, results of Tevatron operations with inclusion of the TEL are presented and analyzed. It is shown that the TEL provides a way to shatter the previously inescapable beam-beam limit.

  12. BEAMS3D Neutral Beam Injection Model

    Energy Technology Data Exchange (ETDEWEB)

    Lazerson, Samuel

    2014-04-14

    With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

  13. Further Development of Ko Displacement Theory for Deformed Shape Predictions of Nonuniform Aerospace Structures

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2009-01-01

    The Ko displacement theory previously formulated for deformed shape predictions of nonuniform beam structures is further developed mathematically. The further-developed displacement equations are expressed explicitly in terms of geometrical parameters of the beam and bending strains at equally spaced strain-sensing stations along the multiplexed fiber-optic sensor line installed on the bottom surface of the beam. The bending strain data can then be input into the displacement equations for calculations of local slopes, deflections, and cross-sectional twist angles for generating the overall deformed shapes of the nonuniform beam. The further-developed displacement theory can also be applied to the deformed shape predictions of nonuniform two-point supported beams, nonuniform panels, nonuniform aircraft wings and fuselages, and so forth. The high degree of accuracy of the further-developed displacement theory for nonuniform beams is validated by finite-element analysis of various nonuniform beam structures. Such structures include tapered tubular beams, depth-tapered unswept and swept wing boxes, width-tapered wing boxes, and double-tapered wing boxes, all under combined bending and torsional loads. The Ko displacement theory, combined with the fiber-optic strain-sensing system, provide a powerful tool for in-flight deformed shape monitoring of unmanned aerospace vehicles by ground-based pilots to maintain safe flights.

  14. Beam Loss in Linacs

    CERN Document Server

    Plum, M.A.

    2016-01-01

    Beam loss is a critical issue in high-intensity accelerators, and much effort is expended during both the design and operation phases to minimize the loss and to keep it to manageable levels. As new accelerators become ever more powerful, beam loss becomes even more critical. Linacs for H- ion beams, such as the one at the Oak Ridge Spallation Neutron Source, have many more loss mechanisms compared to H+ (proton) linacs, such as the one being designed for the European Spallation Neutron Source. Interesting H- beam loss mechanisms include residual gas stripping, H+ capture and acceleration, field stripping, black-body radiation and the recently discovered intra-beam stripping mechanism. Beam halo formation, and ion source or RF turn on/off transients, are examples of beam loss mechanisms that are common for both H+ and H- accelerators. Machine protection systems play an important role in limiting the beam loss.

  15. Charged corpuscular beam detector

    Energy Technology Data Exchange (ETDEWEB)

    Hikawa, H; Nishikawa, Y

    1970-09-29

    The present invention relates to a charged particle beam detector which prevents transient phenomena disturbing the path and focusing of a charged particle beam travelling through a mounted axle. The present invention provides a charged particle beam detector capable of decreasing its reaction to the charge in energy of the charged particle beam even if the relative angle between the mounted axle and the scanner is unstable. The detector is characterized by mounting electrically conductive metal pieces of high melting point onto the face of a stepped, heat-resistant electric insulating material such that the pieces partially overlap each other and individually provide electric signals, whereby the detector is no longer affected by the beam. The thickness of the metal piece is selected so that an eddy current is not induced therein by an incident beam, thus the incident beam is not affected. The detector is capable of detecting a misaligned beam since the metal pieces partially overlap each other.

  16. Method of the nanosecond microstructure creation of the negative ion beam

    International Nuclear Information System (INIS)

    Novikov-Borodin, A.V.

    2001-01-01

    The method of the nanosecond microstructure creation of the negative ion beam with nanosecond edge times is presented. The method of creation does not destroy the beam compensation by the residual gas,so it available for low-energy beams. Such effects as a beam divergence and,therefore,a bad beam transport are overcome. The two plate travelling wave chopper is used.The special shape of the plate deflecting voltage is needed. The estimations and a comparison with the existing methods of a beam deflection are presented

  17. Scattering of a high-order Bessel beam by a spheroidal particle

    Science.gov (United States)

    Han, Lu

    2018-05-01

    Within the framework of generalized Lorenz-Mie theory (GLMT), scattering from a homogeneous spheroidal particle illuminated by a high-order Bessel beam is formulated analytically. The high-order Bessel beam is expanded in terms of spheroidal vector wave functions, where the spheroidal beam shape coefficients (BSCs) are computed conveniently using an intrinsic method. Numerical results concerning scattered field in the far zone are displayed for various parameters of the incident Bessel beam and of the scatter. These results are expected to provide useful insights into the scattering of a Bessel beam by nonspherical particles and particle manipulation applications using Bessel beams.

  18. Advanced electron beam techniques

    International Nuclear Information System (INIS)

    Hirotsu, Yoshihiko; Yoshida, Yoichi

    2007-01-01

    After 100 years from the time of discovery of electron, we now have many applications of electron beam in science and technology. In this report, we review two important applications of electron beam: electron microscopy and pulsed-electron beam. Advanced electron microscopy techniques to investigate atomic and electronic structures, and pulsed-electron beam for investigating time-resolved structural change are described. (author)

  19. Beam Dynamics for ARIA

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-10-14

    Beam dynamics issues are assessed for a new linear induction electron accelerator being designed for flash radiography of large explosively driven hydrodynamic experiments. Special attention is paid to equilibrium beam transport, possible emittance growth, and beam stability. It is concluded that a radiographic quality beam will be produced possible if engineering standards and construction details are equivalent to those on the present radiography accelerators at Los Alamos.

  20. Crossed beam experiments

    International Nuclear Information System (INIS)

    Dolder, K.T.

    1976-01-01

    Many natural phenomena can only be properly understood if one has a detailed knowledge of interactions involving atoms, molecules, ions, electrons or photons. In the laboratory these processes are often studied by preparing beams of two types of particle and observing the reactions which occur when the beams intersect. Some of the more interesting of these crossed beam experiments and their results are discussed. Proposals to extend colliding beam techniques to high energy particle physics are also outlined. (author)

  1. Shaping 3-D boxes

    DEFF Research Database (Denmark)

    Stenholt, Rasmus; Madsen, Claus B.

    2011-01-01

    Enabling users to shape 3-D boxes in immersive virtual environments is a non-trivial problem. In this paper, a new family of techniques for creating rectangular boxes of arbitrary position, orientation, and size is presented and evaluated. These new techniques are based solely on position data...

  2. Tornado-Shaped Curves

    Science.gov (United States)

    Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio

    2017-01-01

    In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.

  3. Sounds Exaggerate Visual Shape

    Science.gov (United States)

    Sweeny, Timothy D.; Guzman-Martinez, Emmanuel; Ortega, Laura; Grabowecky, Marcia; Suzuki, Satoru

    2012-01-01

    While perceiving speech, people see mouth shapes that are systematically associated with sounds. In particular, a vertically stretched mouth produces a /woo/ sound, whereas a horizontally stretched mouth produces a /wee/ sound. We demonstrate that hearing these speech sounds alters how we see aspect ratio, a basic visual feature that contributes…

  4. Aerodynamically shaped vortex generators

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Velte, Clara Marika; Øye, Stig

    2016-01-01

    An aerodynamically shaped vortex generator has been proposed, manufactured and tested in a wind tunnel. The effect on the overall performance when applied on a thick airfoil is an increased lift to drag ratio compared with standard vortex generators. Copyright © 2015 John Wiley & Sons, Ltd....

  5. Bend me, shape me

    CERN Multimedia

    2002-01-01

    A Japanese team has found a way to bend and shape silicon substrates by growing a thin layer of diamond on top. The technique has been proposed as an alternative to mechanical bending, which is currently used to make reflective lenses for X-ray systems and particle physics systems (2 paragraphs).

  6. Coordination of hand shape.

    Science.gov (United States)

    Pesyna, Colin; Pundi, Krishna; Flanders, Martha

    2011-03-09

    The neural control of hand movement involves coordination of the sensory, motor, and memory systems. Recent studies have documented the motor coordinates for hand shape, but less is known about the corresponding patterns of somatosensory activity. To initiate this line of investigation, the present study characterized the sense of hand shape by evaluating the influence of differences in the amount of grasping or twisting force, and differences in forearm orientation. Human subjects were asked to use the left hand to report the perceived shape of the right hand. In the first experiment, six commonly grasped items were arranged on the table in front of the subject: bottle, doorknob, egg, notebook, carton, and pan. With eyes closed, subjects used the right hand to lightly touch, forcefully support, or imagine holding each object, while 15 joint angles were measured in each hand with a pair of wired gloves. The forces introduced by supporting or twisting did not influence the perceptual report of hand shape, but for most objects, the report was distorted in a consistent manner by differences in forearm orientation. Subjects appeared to adjust the intrinsic joint angles of the left hand, as well as the left wrist posture, so as to maintain the imagined object in its proper spatial orientation. In a second experiment, this result was largely replicated with unfamiliar objects. Thus, somatosensory and motor information appear to be coordinated in an object-based, spatial-coordinate system, sensitive to orientation relative to gravitational forces, but invariant to grasp forcefulness.

  7. How life shaped Earth.

    Science.gov (United States)

    Gross, Michael

    2015-10-05

    Earth is much more complex than all the other solar system objects that we know. Thanks to its rich and diverse geology, our planet can offer habitats to a wide range of living species. Emerging insights suggest that this is not just a happy coincidence, but that life itself has in many ways helped to shape the planet.

  8. Interactive shape metamorphosis

    Science.gov (United States)

    Chen, David T.; State, Andrei; Banks, David

    1994-01-01

    A technique for controlled metamorphosis between surfaces in 3-space is described. Well-understood techniques to produce shape metamorphosis between models in a 2D parametric space is applied. The user selects morphable features interactively, and the morphing process executes in real time on a high-performance graphics multicomputer.

  9. Fabrication of beam diagnostic components for Superconducting Cyclotron at Kolkata

    International Nuclear Information System (INIS)

    Roy, S.; Bhattacharya, S.; Das, T.; Bhattacharyya, T.K.; Pal, S.; Pal, G.; Mallik, C.; Bhandari, R.K.

    2009-01-01

    The viewer probe and main probe are used for determining the position and current of charged particles as it is accelerated inside the superconducting cyclotron. The viewer probe is used to visually observe the shape of the charged particle beam inside the cyclotron with the help of a borescope. The main probe measures the distribution of charged particles. The viewer probe and main probe are bellow sealed. They can be positioned with an accuracy of 0.5 mm at different radii within the superconducting cyclotron. M9 slit is placed after the exit flange of the cyclotron. It determines the position of the beam leaving the cyclotron. The beam line has slits, faraday cup, beam viewers, collimators, etc. for beam diagnostics. This paper presents the mechanical design and details of beam diagnostic components. (author)

  10. Faraday cup dosimetry in a proton therapy beam without collimation

    International Nuclear Information System (INIS)

    Grusell, Erik; Isacsson, Ulf; Montelius, Anders; Medin, Joakim

    1995-01-01

    A Faraday cup in a proton beam can give an accurate measurement of the number of protons collected by the cup. It is shown that the collection efficiency with a proper design can be close to unity. To be able to calibrate an ionization chamber from such a measurement, as is recommended in some dosimetry protocols, the energy spectrum of the proton beam must be accurately known. This is normally not the case when the lateral beam extension is defined by collimators. Therefore a method for relating an ionization chamber measurement in an uncollimated beam to the total number of protons in the beam has been developed and is described together with experimental results from calibrating an ionization chamber using this method in the therapeutic beam in Uppsala. This method is applicable to ionization chambers of any shape and the accuracy is estimated to be 1.6% (1 SD). (Author)

  11. Iconic representation of particle beams using personal computers

    International Nuclear Information System (INIS)

    Dasgupta, S.; Sarkar, D.; Mallik, C.

    1992-01-01

    The idea of representing the character of a charged particle beam by means of its emittance ellipses, is essentially a mathematical one. For quick understanding of the beam character in a more user-friendly way, unit beam cells with particles having a uniform nature, have been pictured by suitably shaped 3-D solids. The X and Y direction momenta at particular cell areas of the particle beam combine together to give a proportionate orientation to the solid in the pseudo 3-D world of the graphic screen, creating a physical picture of the particle beam. This is expected to facilitate the comprehension of total characteristics of a beam in cases of online control of transport lines and their designs, when interfaced with various ray-tracing programs. The implementation is done in an IBM-PC environment. (author)

  12. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

    Science.gov (United States)

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-12-16

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

  13. High spin studies with radioactive ion beams

    International Nuclear Information System (INIS)

    Garrett, J.D.

    1992-01-01

    The variety of new research possibilities afforded by the culmination of the two frontier areas of nuclear structure: high spin and studies far from nuclear stability (utilizing intense radioactive ion beams) are discussed. Topics presented include: new regions of exotic nuclear shape (e.g. superdeformation, hyperdeformation, and reflection-asymmetric shapes); the population of and consequences of populating exotic nuclear configurations; and complete spectroscopy (i.e. the overlap of state of the art low-and high-spin studies in the same nucleus)

  14. High spin studies with radioactive ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, J D [Oak Ridge National Lab., TN (United States)

    1992-08-01

    The variety of new research possibilities afforded by the culmination of the two frontier areas of nuclear structure: high spin and studies far from nuclear stability (utilizing intense radioactive ion beams) are discussed. Topics presented include: new regions of exotic nuclear shape (e.g. superdeformation, hyperdeformation, and reflection-asymmetric shapes); the population of and consequences of populating exotic nuclear configurations; and, complete spectroscopy (i.e. the overlap of state of the art low- and high-spin studies in the same nucleus). (author). 47 refs., 8 figs.

  15. Beams 92: Proceedings

    International Nuclear Information System (INIS)

    Mosher, D.; Cooperstein, G.

    1993-01-01

    This report contains papers on the following topics: Ion beam papers; electron beam, bremsstrahlung, and diagnostics papers; radiating Z- pinch papers; microwave papers; electron laser papers; advanced accelerator papers; beam and pulsed power applications papers; pulsed power papers; and these papers have been indexed separately elsewhere

  16. High energy beam cooling

    International Nuclear Information System (INIS)

    Berger, H.; Herr, H.; Linnecar, T.; Millich, A.; Milss, F.; Rubbia, C.; Taylor, C.S.; Meer, S. van der; Zotter, B.

    1980-01-01

    The group concerned itself with the analysis of cooling systems whose purpose is to maintain the quality of the high energy beams in the SPS in spite of gas scattering, RF noise, magnet ripple and beam-beam interactions. Three types of systems were discussed. The status of these activities is discussed below. (orig.)

  17. Effect of nonuniform radial density distribution on the space charge dominated beam bunching

    International Nuclear Information System (INIS)

    Sing Babu, P.; Goswami, A.; Pandit, V. S.

    2011-01-01

    Beam dynamics of a space charge dominated beam during the bunch compression is studied self consistently for the case of fixed shape non-uniform bell shape and hollow shape density distributions in the transverse direction. We have used thick slices at different parts of the beam to account for variation in the beam radius in the study of the transverse dynamics. The longitudinal dynamics has been studied using the disc model. The axial variation of the radius of the slices and emittance growth arising from the phase dependence of the transverse rf forces are also included in the simulation. We have modified the beam envelope equation to take into account the longitudinal space charge effect on the transverse motion which arises due to the finite bunch size. To demonstrate the application of the theoretical formulations developed, we have studied a sinusoidal beam bunching system and presented detailed numerical results.

  18. Beam-beam interaction working group summary

    International Nuclear Information System (INIS)

    Siemann, R.H.

    1995-01-01

    The limit in hadron colliders is understood phenomenologically. The beam-beam interaction produces nonlinear resonances and makes the transverse tunes amplitude dependent. Tune spreads result from the latter, and as long as these tune spreads do not overlap low order resonances, the lifetime and performance is acceptable. Experience is that tenth and sometimes twelfth order resonances must be avoided, and the hadron collider limit corresponds roughly to the space available between resonances of that and lower order when operating near the coupling resonance. The beam-beam interaction in e + e - colliders is not understood well. This affects the performance of existing colliders and could lead to surprises in new ones. For example. a substantial amount of operator tuning is usually required to reach the performance limit given above, and this tuning has to be repeated after each major shutdown. The usual interpretation is that colliding beam performance is sensitive to small lattice errors, and these are being reduced during tuning. It is natural to ask what these errors are, how can a lattice be characterized to minimize tuning time, and what aspects of a lattice should receive particular attention when a new collider is being designed. The answers to this type of question are not known, and developing ideas for calculations, simulations and experiments that could illuminate the details of the beam-beam interaction was the primary working group activity

  19. Beam uniformity of flat top lasers

    Science.gov (United States)

    Chang, Chao; Cramer, Larry; Danielson, Don; Norby, James

    2015-03-01

    Many beams that output from standard commercial lasers are multi-mode, with each mode having a different shape and width. They show an overall non-homogeneous energy distribution across the spot size. There may be satellite structures, halos and other deviations from beam uniformity. However, many scientific, industrial and medical applications require flat top spatial energy distribution, high uniformity in the plateau region, and complete absence of hot spots. Reliable standard methods for the evaluation of beam quality are of great importance. Standard methods are required for correct characterization of the laser for its intended application and for tight quality control in laser manufacturing. The International Organization for Standardization (ISO) has published standard procedures and definitions for this purpose. These procedures have not been widely adopted by commercial laser manufacturers. This is due to the fact that they are unreliable because an unrepresentative single-pixel value can seriously distort the result. We hereby propose a metric of beam uniformity, a way of beam profile visualization, procedures to automatically detect hot spots and beam structures, and application examples in our high energy laser production.

  20. Testing Long-Range Beam-Beam Compensation for the LHC Luminosity Upgrade

    CERN Document Server

    Rijoff, T L

    2012-01-01

    The performance of the Large Hadron Collider (LHC) at CERN and its minimum crossing angle are limited by the effect of long-range beam-beam collisions. A wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, or higher beam intensity. A prototype long-range wire compensator could be installed in the LHC by 2014/15. Since the originally reserved position for such a wire compensator is not available for this first step, we explore other possible options. Our investigations consider various longitudinal and transverse locations, different wire shapes, different optics configurations and several crossing angles between the two colliding beams. Simulations are carried out with the weak-strong code BBtrack. New postprocessing tools are introduced to analyse tune footprints and particle stability. In particular, a new method for the Lyapunov coefficient calculation is implemented. Submitted as "Tesi di laurea" at the University of Milano, 2012.