Micropole undulator

DOEpatents

Csonka, Paul L.; Tatchyn, Roman O.

1989-01-24

Micropole undulators for use in the generation of x-rays from moving charged particles and methods for manufacturing such undulators are disclosed. One type of micropole undulator has two jaws containing rows of spaced apart poles arranged so that each pole produces a magnetic field aligned with all other similar fields. An external biasing field extends through the jaws so that an overall undulator field of substantially sinusoidal shape and substantially zero average value extends along the undulator axis. Preferably, the poles are bars formed of a magnetizable, but unmagnetized, material so that, after the jaws are assembled, all of the bars can be magnetized simultaneously in a uniform magnetic field of suitable strength. Another type of micropole undulator incorporates two parallel layers which have been magnetized to provide rows of alternating magnetic fields extending in opposite directions, the layers being positioned between the pole faces of a highly magnetically permeable material with the south poles of one layer opposite the north poles of the other. Poles in the layers are formed by subjecting successive regions of each layer to oppositely directed and suitably varied magnetizing forces.

Indentation and overall compression behavior of multilayered thin-film composites. Effect of undulating layer geometry

DOE PAGES

Jamison, Ryan D.; Shen, Y. -L.

2015-03-19

Two finite element models are used to investigate the behavior of aluminum/silicon carbide thin-film layered composites with imperfect internal geometry when subjected to various loadings. In both models, undulating layers are represented by regular waveforms with various amplitudes, wavelengths, and phase offsets. First, uniaxial compressive loading of the composite is considered. The modulus and stress/strain response of the composite is sensitive to both loading direction and frequency of the undulation. Second, the nanoindentation response of the composite is investigated. The derived hardness and modulus are shown to be sensitive to the presence of undulating layers and the relative size ofmore » the indenter to the undulation. Undulating layers create bands of tensile and compressive stress in the indentation direction that are significantly different from the flat layers. The amount of equivalent plastic strain in the Al layers is increased by the presence of undulating layers. The correlations between the two forms of loading, and the implications to composite property measurement are carefully examined in this study.« less

Feasibility and electromagnetic analysis of a REBCO superconducting undulator

DOE PAGES

Kesgin, Ibrahim; Kasa, Matthew; Doose, Charles; ...

2016-03-17

Recent advances in second-generation (2G) high temperature superconducting (HTS) coated conductors (CCs) have made them very attractive for new applications such as undulators. In this study, we have, for the first time, experimentally evaluated a design to validate applicability of 2G-HTS tapes for next generation undulator magnetic structures. A two-period undulator magnetic core was fabricated and 2G-HTS CCs were successfully wound onto the undulator core. The performance of the undulator magnetic structure was investigated and the highest engineering current density, J e, in such configuration reported yet was obtained. A new U-slit tape configuration was used to reduce the numbermore » of resistive joints and it was shown that with this new technique affordable levels of resistance values can be achieved for short length undulators. The ferromagnetic core was designed such as to accommodate winding the U-slit tapes. Finally, test results indicated that the winding and the soldering procedures are successful and do not deteriorate the performance of the 2G-HTS tapes.« less

Investigation of the polarization state of dual APPLE-II undulators.

PubMed

Hand, Matthew; Wang, Hongchang; Dhesi, Sarnjeet S; Sawhney, Kawal

2016-01-01

The use of an APPLE II undulator is extremely important for providing a high-brilliance X-ray beam with the capability to switch between various photon beam polarization states. A high-precision soft X-ray polarimeter has been used to systematically investigate the polarization characteristics of the two helical APPLE II undulators installed on beamline I06 at Diamond Light Source. A simple data acquisition and processing procedure has been developed to determine the Stokes polarization parameters for light polarized at arbitrary linear angles emitted from a single undulator, and for circularly polarized light emitted from both undulators in conjunction with a single-period undulator phasing unit. The purity of linear polarization is found to deteriorate as the polarization angle moves away from the horizontal and vertical modes. Importantly, a negative correlation between the degree of circular polarization and the photon flux has been found when the phasing unit is used.

A fast analytical undulator model for realistic high-energy FEL simulations

NASA Astrophysics Data System (ADS)

Tatchyn, R.; Cremer, T.

1997-02-01

A number of leading FEL simulation codes used for modeling gain in the ultralong undulators required for SASE saturation in the <100 Å range employ simplified analytical models both for field and error representations. Although it is recognized that both the practical and theoretical validity of such codes could be enhanced by incorporating realistic undulator field calculations, the computational cost of doing this can be prohibitive, especially for point-to-point integration of the equations of motion through each undulator period. In this paper we describe a simple analytical model suitable for modeling realistic permanent magnet (PM), hybrid/PM, and non-PM undulator structures, and discuss selected techniques for minimizing computation time.

Proposal of a Bulk HTSC Staggered Array Undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kii, Toshiteru; Kinjo, Ryota; Bakr, Mahmoud A.

We proposed a new type of undulator based on bulk high-T{sub c} superconductors (HTSC) which consists of a single solenoid and a stacked array of bulk HTSC. The main advantage of this configuration is that a mechanical structure is not required to produce and control the undulator field. In order to perform a proof of principle experiment, we have developed a prototype of bulk HTSC staggered array undulator using 11 pairs of DyBaCuO bulk superconductors and a normal conducting solenoid. Experimental results obtained by using the prototype undulator and numerical results obtained by a loop current model based on themore » Bean mode for a type-II superconductor were compared.« less

First observation of undulator radiation from APPLE-1

NASA Astrophysics Data System (ADS)

Sasaki, Shigemi; Shimada, Taihei; Yanagida, Ken-ichi; Kobayashi, Hideki; Miyahara, Yoshikazu

1994-08-01

Various polarized radiation was observed in the visible region generated by the new type undulator APPLE-1 (Advanced Planar Polarized Light Emitted - 1). The undulator was installed in the low energy electron storage ring JSR and we have succeeded in observing linearly polarized radiation in both planes and circularly polarized radiation with the aid of a Wollaston prism. During the process of shifting the arrays and changing the undulator gap, no noticeable change of radiation axis was observed.

Development and operation of a Pr 2 Fe 14 B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

DOE PAGES

Benabderrahmane, C.; Valleau, M.; Ghaith, A.; ...

2017-03-02

Short period, high field undulators are used to produce hard x-rays on synchrotron radiation based storage ring facilities of intermediate energy and enable short wavelength free electron laser. Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE 2Fe 14B (Rare Earth based magnets) at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr 2Fe 14B instead of Nd 2Fe 14B, which is generally employed for undulators, avoids the limitation caused by the spin reorientation transition phenomenon, and simplifies the cooling system by allowing the working temperature of the undulator to be directlymore » at the liquid nitrogen one (77 K). We describe here the development of a full scale (2 m), 18 mm period Pr 2Fe 14B cryogenic permanent magnet undulator (U18). The design, construction and optimization, as well as magnetic measurements and shimming at low temperature are presented. In conclusion, the commissioning and operation of the undulator with the electron beam and spectrum measurement using the Nanoscopmium beamline at SOLEIL are also reported.« less

Proposed Laser-driven, Dielectric Microstructure Few-cm Long Undulator for Attosecond Coherent X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plettner, T; Byer, R.L.; /Stanford U., Ginzton Lab.

This article presents the concept of an all-dielectric laser-driven undulator for the generation of coherent X-rays. The proposed laser-driven undulator is expected to produce internal deflection forces equivalent to a several-Tesla magnetic field acting on a speed-of-light particle. The key idea for this laser-driven undulator is its ability to provide phase synchronicity between the deflection force and the electron beam for a distance that is much greater than the laser wavelength. The potential advantage of this undulator is illustrated with a possible design example that assumes a small laser accelerator which delivers a 2 GeV, 1 pC, 1 kHz electronmore » bunch train to a 10 cm long, 1/2 mm period laser-driven undulator. Such an undulator could produce coherent X-ray pulses with {approx}10{sup 9} photons of 64 keV energy. The numerical modeling for the expected X-ray pulse shape was performed with GENESIS, which predicts X-ray pulse durations in the few-attosecond range. Possible applications for nonlinear electromagnetic effects from these X-ray pulses are briefly discussed.« less

Development and operation of a Pr 2 Fe 14 B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benabderrahmane, C.; Valleau, M.; Ghaith, A.

Short period, high field undulators are used to produce hard x-rays on synchrotron radiation based storage ring facilities of intermediate energy and enable short wavelength free electron laser. Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE 2Fe 14B (Rare Earth based magnets) at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr 2Fe 14B instead of Nd 2Fe 14B, which is generally employed for undulators, avoids the limitation caused by the spin reorientation transition phenomenon, and simplifies the cooling system by allowing the working temperature of the undulator to be directlymore » at the liquid nitrogen one (77 K). We describe here the development of a full scale (2 m), 18 mm period Pr 2Fe 14B cryogenic permanent magnet undulator (U18). The design, construction and optimization, as well as magnetic measurements and shimming at low temperature are presented. In conclusion, the commissioning and operation of the undulator with the electron beam and spectrum measurement using the Nanoscopmium beamline at SOLEIL are also reported.« less

Polarization characteristics of radiation in both 'light' and conventional undulators

NASA Astrophysics Data System (ADS)

Potylitsyn, A. P.; Kolchuzhkin, A. M.; Strokov, S. A.

2017-07-01

As a rule, an intensity spectrum of undulator radiation (UR) is calculated by using the classical approach, even for electron energy higher than 10 GeV. Such a spectrum is determined by an electron trajectory in an undulator while neglecting radiation loss. Using Planck's law, the UR photon spectrum can be calculated from the obtained intensity spectrum, for both linear and nonlinear regimes. The electron radiation process in a field of strong electromagnetic waves is considered within the quantum electrodynamics framework, using the Compton scattering process or radiation in a 'light' undulator. A comparison was made of the results from using these two approaches, for UR spectra generated by 250-GeV electrons in an undulator with a 11.5-mm period; this comparison shows that they coincide with high accuracy. The characteristics of the collimated UR beam (i.e. spectrum and circular polarization) were simulated while taking into account the discrete process of photon emission along an electron trajectory in both undulator types. Both spectral photon distributions and polarization dependence on photon energy are 'smoothed', in comparison to that expected for a long undulator-the latter of which considers the ILC positron source (ILC Technical Design Report).

Development and operation of a Pr2 Fe14 B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

NASA Astrophysics Data System (ADS)

Benabderrahmane, C.; Valléau, M.; Ghaith, A.; Berteaud, P.; Chapuis, L.; Marteau, F.; Briquez, F.; Marcouillé, O.; Marlats, J.-L.; Tavakoli, K.; Mary, A.; Zerbib, D.; Lestrade, A.; Louvet, M.; Brunelle, P.; Medjoubi, K.; Herbeaux, C.; Béchu, N.; Rommeluere, P.; Somogyi, A.; Chubar, O.; Kitegi, C.; Couprie, M.-E.

2017-03-01

Short period, high field undulators are used to produce hard x-rays on synchrotron radiation based storage ring facilities of intermediate energy and enable short wavelength free electron laser. Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE2 Fe14B (Rare Earth based magnets) at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr2 Fe14B instead of Nd2 Fe14B , which is generally employed for undulators, avoids the limitation caused by the spin reorientation transition phenomenon, and simplifies the cooling system by allowing the working temperature of the undulator to be directly at the liquid nitrogen one (77 K). We describe here the development of a full scale (2 m), 18 mm period Pr2 Fe14B cryogenic permanent magnet undulator (U18). The design, construction and optimization, as well as magnetic measurements and shimming at low temperature are presented. The commissioning and operation of the undulator with the electron beam and spectrum measurement using the Nanoscopmium beamline at SOLEIL are also reported.

Tapered undulator for SASE FELs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je

We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

Transverse gradient in Apple-type undulators

PubMed Central

Calvi, M.; Camenzuli, C.; Prat, E.; Schmidt, Th.

2017-01-01

Apple-type undulators are globally recognized as the most flexible devices for the production of variable polarized light in the soft X-ray regime, both at synchrotron and free-electron laser facilities. Recently, the implementation of transverse gradient undulators has been proposed to enhance the performance of new generation light sources. In this paper it is demonstrated that Apple undulators do not only generate linear and elliptical polarized light but also variable transverse gradient under certain conditions. A general theoretical framework is introduced to evaluate the K-value and its transverse gradient for an Apple undulator, and formulas for all regular operational modes and different Apple types (including the most recent Delta type and Apple X) are calculated and critically discussed. PMID:28452751

Aerodynamics and Aerothermodynamics of undulated re-entry vehicles

NASA Astrophysics Data System (ADS)

Kaushikh, K.; Arunvinthan, S.; Pillai, S. Nadaraja

2018-01-01

Aerodynamic and aerothermodynamic analysis is a fundamental basis for the design of a hypersonic vehicle. In this work, aerodynamic and aerothermodynamic analyses of a blunt body vehicle with undulations on its after-body are studied with the help of numerical simulations. A crew exploration vehicle (CEV) is taken for initial analysis and undulations with varying amplitude and wavelength are introduced on CEV's after-body. Numerical simulations were carried out for CEV and for CEV with undulations at Mach 3.0 and 7.0 for angles of attack ranging from -20° to +20° with increments of +5°. The results show that introduction of undulations did not have a significant impact on mono stability and lift-drag characteristics of the vehicle. It was also observed that introduction of undulations improved the aerothermodynamic characteristics of CEV. A reduction of about 36% in maximum heat flux at Mach 3.0 and about 21% at Mach 7.0 compared to the maximum heat flux for CEV was observed.

Magnet system optimization for segmented adaptive-gap in-vacuum undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitegi, C., E-mail: ckitegi@bnl.gov; Chubar, O.; Eng, C.

2016-07-27

Segmented Adaptive Gap in-vacuum Undulator (SAGU), in which different segments have different gaps and periods, promises a considerable spectral performance gain over a conventional undulator with uniform gap and period. According to calculations, this gain can be comparable to the gain achievable with a superior undulator technology (e.g. a room-temperature in-vacuum hybrid SAGU would perform as a cryo-cooled hybrid in-vacuum undulator with uniform gap and period). However, for reaching the high spectral performance, SAGU magnetic design has to include compensation of kicks experienced by the electron beam at segment junctions because of different deflection parameter values in the segments. Wemore » show that such compensation to large extent can be accomplished by using a passive correction, however, simple correction coils are nevertheless required as well to reach perfect compensation over a whole SAGU tuning range. Magnetic optimizations performed with Radia code, and the resulting undulator radiation spectra calculated using SRW code, demonstrating a possibility of nearly perfect correction, are presented.« less

Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator - presentation slides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wootton, Kent

2015-09-17

Direct emittance measurement based on vertical undulator is discussed. Emittance was evaluated from peak ratios, the smallest measured being =0.9 ±0.3 pm rad. The angular distribution of undulator radiation departs from Gaussian approximations, a fact of which diffraction-limited light sources should be aware.

MaRIE Undulator & XFEL Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Dinh Cong; Marksteiner, Quinn R.; Anisimov, Petr Mikhaylovich

The 22 slides in this presentation treat the subject under the following headings: MaRIE XFEL Performance Parameters, Input Electron Beam Parameters, Undulator Design, Genesis Simulations, Risks, and Summary It is concluded that time-dependent Genesis simulations show the MaRIE XFEL can deliver the number of photons within the required bandwidth, provided a number of assumptions are met; the highest risks are associated with the electron beam driving the XFEL undulator; and risks associated with the undulator and/or distributed seeding technique may be evaluated or retired by performing early validation experiments.

Design of a magnetic circuit for a cryogenic undulator in Taiwan photon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jui-Che, E-mail: huang.juiche@nsrrc.org.tw; Kuo, Cheng-Ying; Yang, Chin-Kang

2016-07-27

The plan for beamlines in Phase II at Taiwan Photon Source is to construct two new BioSAXS and nano-ARPES beamlines. A highly brilliant light source can be produced with a cryogenic undulator, and many synchrotron facilities have been developed and operated with these in their storage rings. The development of a cryogenic undulator became a target for a light source in TPS phase II. A cryogenic undulator with period of length 15 mm will be made in a hybrid magnetic structure, and use PrFeB permanent-magnet materials. A maximum magnetic field 1.31 T is estimated at gap 4 mm and temperaturemore » about 100 K. The spectral performance of a TPS cryogenic undulator is presented in this paper.« less

Simulation Study of the Helical Superconducting Undulator Installation at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sajaev, V.; Borland, M.; Sun, Y.

A helical superconducting undulator is planned for installation at the APS. Such an installation would be first of its kind – helical devices were never installed in synchrotron light sources before. Due to its reduced horizontal aperture, a lattice modification is required to accommodate for large horizontal oscillations during injection. We describe the lattice change details and show the new lattice experimental test results. To understand the effect of the undulator on single-particle dynamics, first, its kick maps were computed using different methods. We have found that often-used Elleaume formula* for kick maps gives wrong results for this undulator. Wemore » then used the kick maps obtained by other methods to simulate the effect of the undulator on injection and lifetime.« less

Fast Beam-Based BPM Calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertsche, K.; Loos, H.; Nuhn, H.-D.

2012-10-15

The Alignment Diagnostic System (ADS) of the LCLS undulator system indicates that the 33 undulator quadrupoles have extremely high position stability over many weeks. However, beam trajectory straightness and lasing efficiency degrade more quickly than this. A lengthy Beam Based Alignment (BBA) procedure must be executed every two to four weeks to re-optimize the X-ray beam parameters. The undulator system includes RF cavity Beam Position Monitors (RFBPMs), several of which are utilized by an automatic feedback system to align the incoming electron-beam trajectory to the undulator axis. The beam trajectory straightness degradation has been traced to electronic drifts of themore » gain and offset of the BPMs used in the beam feedback system. To quickly recover the trajectory straightness, we have developed a fast beam-based procedure to recalibrate the BPMs. This procedure takes advantage of the high-precision monitoring capability of the ADS, which allows highly repeatable positioning of undulator quadrupoles. This report describes the ADS, the position stability of the LCLS undulator quadrupoles, and some results of the new recovery procedure.« less

The indirect effects on the computation of geoid undulations

NASA Technical Reports Server (NTRS)

Wichiencharoen, C.

1982-01-01

The indirect effects on the geoid computation due to the second method of Helmert's condensation were studied. when Helmert's anomalies are used in Stokes's equation, there are three types of corrections to the free air geoid. The first correction, the indirect effect on geoid undulation due to the potential change in Helmert's reduction, had a maximum value of 0.51 meters in the test area covering the United States. The second correction, the attraction change effect on geoid undulation, had a maximum value of 9.50 meters when the 10 deg cap was used in Stokes' equation. The last correction, the secondary indirect effect on geoid undulatin, was found negligible in the test area. The corrections were applied to uncorrected free air geoid undulations at 65 Doppler stations in the test area and compared with the Doppler undulations. Based on the assumption that the Doppler coordinate system has a z shift of 4 meters with respect to the geocenter, these comparisons showed that the corrections presented in this study yielded improved values of gravimetric undulations.

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

NASA Astrophysics Data System (ADS)

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan; Yoon, Moohyun; Zhou, Guanqun

2017-12-01

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulator tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (˜10 %) provides effective suppression of the sideband instability in the postsaturation regime.

UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakeman, M.S.; Fawley, W.M.; Leemans, W. P.

to couple the THUNDER undulator to the LOASIS Lawrence Berkeley National Laboratory (LBNL) laser wakefield accelerator (LWFA). Currently the LWFA has achieved quasi-monoenergetic electron beams with energies up to 1 GeV. These ultra-short, high-peak-current, electron beams are ideal for driving a compact XUV free electron laser (FEL). Understanding the electron beam properties such as the energy spread and emittance is critical for achieving high quality light sources with high brightness. By using an insertion device such as an undulator and observing changes in the spontaneous emission spectrum, the electron beam energy spread and emittance can be measured with high precision.more » The initial experiments will use spontaneous emission from 1.5 m of undulator. Later experiments will use up to 5 m of undulator with a goal of a high gain, XUV FEL.« less

Observation of an optical vortex beam from a helical undulator in the XUV region.

PubMed

Kaneyasu, Tatsuo; Hikosaka, Yasumasa; Fujimoto, Masaki; Iwayama, Hiroshi; Hosaka, Masahito; Shigemasa, Eiji; Katoh, Masahiro

2017-09-01

The observation of an optical vortex beam at 60 nm wavelength, produced as the second-harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation.

Preliminary Analysis of a 27.5 mm Period Undulator for the MBA Lattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abliz, M.; Grimmer, J.

2016-07-27

The magnetic design of a 27.5 mm period undulator was performed for the APS MBA Lattice. One purpose of the magnetic design was to decrease the magnetic force in order to operate the undulator successfully at a smaller gap compared to the existing 27 mm undulator at the APS. As a result, the magnetic force is decreased by about 18% at a gap of 11 mm and the total volume of the magnet and the pole is decreased by approximately 22% with the new model. The calculated effective field with the new model was 172 G higher than the existingmore » 27-mm period undulator with a gap of 11 mm. The calculated field roll-off with the new optimized model is within the requirements of the MBA, in the range of ± 5 mm.« less

Power spectra of geoid undulations. [definition of altimeter design requirements for geoid recovery

NASA Technical Reports Server (NTRS)

Brown, R. D.

1975-01-01

Data from spacecraft altimeters are expected to contribute to an improved determination of the marine geoid. To better define altimeter system design requirements for geoid recovery, amplitudes of geoid undulations at short wavelengths were examined. Models of detailed geoids in selected areas around the earth, developed from a combination of satellite derived spherical harmonics and 1 deg-by-1 deg area mean free-air gravity anomalies, were subjected to a spectral analysis. The resulting undulation power spectra were compared to existing estimates for the magnitude of geoid undulations at short wavelengths. The undulation spectra were found to be consistent with Kaula's rule of thumb, following an inverse third power relationship with spatial frequency for wavelengths at least as small as 300 km. The requirements imposed by this relationship on altimeter accuracy, data rate, and horizontal resolution to meet the goal of a detailed geoid description are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

TREMAINE,A.; MUROKH,A.; WANG,X.J.

The VISA experiment is designed to reach and study saturation in a high gain 800nm SASE FEL at the Brookhaven Accelerator Test Facility (ATF). To do this, the undulator must be aligned at first to within 20 {micro}m with use of a laser interferometric system. Once aligned, any small movements from the aligned position will greatly detriment the SASE FEL performance thus making continuous monitoring of the undulator position necessary. This is quite a complicated task since the 4m undulator is made up of four 1m sections enclosed in a vacuum chamber. We have developed an in situ optical systemmore » to monitor the undulator position with an accuracy better than 10 {micro}m. In addition, we have demonstrated the accuracy of this system by bringing the grossly misaligned VISA undulator ({approximately} 500 {micro}m in some locations) into alignment and attaining very high gain of the SASE FEL.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

As part of the R and D program towards a fourth generation light source, a Self-Amplified Spontaneous Emission (SASE) demonstration is being prepared. The Visible-Infrared SASE Amplifier (VISA) undulator will be installed at Brookhaven National Laboratory by the end of the year. The VISA undulator is an in-vacuum, 4-meter long, 1.8 cm period, pure-permanent magnet device, with a novel, strong focusing, permanent magnet FODO array included within the fixed, 6 mm undulator gap. The undulator is constructed of 99 cm long segments. To attain maximum SASE gain requires establishing overlap of electron and photon beams to within 50 {micro}m rms.more » This imposes challenging tolerances on mechanical fabrication and magnetic field quality, and necessitates use of laser straightness interferometry for calibration and alignment of the magnetic axes of the undulator segments. This paper describes the magnetic centerline determination, and the fiducialization and alignment processes which were performed to meet the tolerance goal.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruland, Robert E.

As part of the R and D program towards a fourth generation light source, a Self-Amplified Spontaneous Emission (SASE) demonstration is being prepared. The Visible-Infrared SASE Amplifier (VISA) undulator is being installed at Brookhaven National Laboratory. The VISA undulator is an in-vacuum, 4-meter long, 1.8 cm period, pure-permanent magnet device, with a novel, strong focusing, permanent magnet FODO array included within the fixed, 6 mm undulator gap. The undulator is constructed of 99 cm long segments. To attain maximum SASE gain requires establishing overlap of electron and photon beams to within 50 pm rms. This imposes challenging tolerances on mechanicalmore » fabrication and magnetic field quality, and necessitates use of laser straightness interferometry for calibration and alignment of the magnetic axes of the undulator segments. This paper describes the magnetic centerline determination, and the fiducialization and alignment processes, which were performed to meet the tolerance goal.« less

High-temperature superconducting undulator magnets

DOE PAGES

Kesgin, Ibrahim; Kasa, Matthew; Ivanyushenkov, Yury; ...

2017-02-13

Here, this paper presents test results on a prototype superconducting undulator magnet fabricated using 15% Zr-doped rare-earth barium copper oxide high temperature superconducting (HTS) tapes. On an 11-pole magnet we demonstrate an engineering current density, J e, of more than 2.1 kA mm -2 at 4.2 K, a value that is 40% higher than reached in comparable devices wound with NbTi-wire, which is used in all currently operating superconducting undulators. A novel winding scheme enabling the continuous winding of tape-shaped conductors into the intricate undulator magnets as well as a partial interlayer insulation procedure were essential in reaching this advancemore » in performance. Currently, there are rapid advances in the performance of HTS; therefore, achieving even higher current densities in an undulator structure or/and operating it at temperatures higher than 4.2 K will be possible, which would substantially simplify the cryogenic design and reduce overall costs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

MUROKH,A.; FRIGOLA,P.; ET AL

We describe a diagnostics system developed, to measure exponential gain properties and the electron beam dynamics inside the strong focusing 4-m long undulator for the VISA (Visible to Infrared SASE Amplifier) FEL. The technical challenges included working inside the small undulator gap, optimizing the electron beam diagnostics in the high background environment of the spontaneous undulator radiation, multiplexing and transporting the photon beam. Initial results are discussed.

Irradiation caused performance losses of undulators equipped with Sm2Co17 magnets

NASA Astrophysics Data System (ADS)

Heidrich, S.; Aulenbacher, K.; Donders, S.; Nikipelov, A.

2018-06-01

The effects of beam losses on the performance of undulators equipped with Sm2Co17 magnets were investigated at the 855 MeV beamline of the Mainzer Microtron MAMI. Therefore, different cases containing undulator components as well as complete undulator assemblies were irradiated. Different types of shielding were used to distinguish the magnetic field degradation caused by neutrons from the degradation caused by electrons and photons. The results of each case were put in relation with the expected beam losses of a conceptional 10 kW free-electron-laser (FEL) based on an electron beam with 34 MW beam power.

Generation of a wakefield undulator in plasma with transverse density gradient

DOE PAGES

Stupakov, Gennady V.

2017-11-30

Here, we show that a short relativistic electron beam propagating in a plasma with a density gradient perpendicular to the direction of motion generates a wakefield in which a witness bunch experiences a transverse force. A density gradient oscillating along the beam path would create a periodically varying force$-$an undulator, with an estimated strength of the equivalent magnetic field more than ten Tesla. This opens an avenue for creation of a high-strength, short-period undulators, which eventually may lead to all-plasma, free electron lasers where a plasma wakefield acceleration is naturally combined with a plasma undulator in a unifying, compact setup.

Perspectives on micropole undulators in synchrotron radiation technology

NASA Astrophysics Data System (ADS)

Tatchyn, Roman; Csonka, Paul; Toor, Arthur

1989-07-01

Micropole undulators promise to advance synchrotron radiation (SR) technology in two distinct ways. The first is in the development of economical, low-energy storage rings, or linacs, as soft x-ray sources, and the second is in the opening up of gamma-ray spectral ranges on high-energy storage rings. In this paper the promise and current status of micropole undulator (MPU) technology are discussed, and a review of some practical obstacles to the implementation of MPU's on present-day storage rings is given. Some successful results of recent performance measurements of micropole undulators on the Lawrence Livermore National Laboratory linac are briefly summarized.

A noncoherent model for microwave emissions and backscattering from the sea surface

NASA Technical Reports Server (NTRS)

Wu, S. T.; Fung, A. K.

1973-01-01

The two-scale (small irregularities superimposed upon large undulations) scattering theory proposed by Semyonov was extended and used to compute microwave apparent temperature and the backscattering cross section from ocean surfaces. The effect of the small irregularities upon the scattering characteristics of the large undulations is included by modifying the Fresnel reflection coefficients; whereas the effect of the large undulations upon those of the small irregularities is taken into account by averaging over the surface normals of the large undulations. The same set of surface parameters is employed for a given wind speed to predict both the scattering and the emission characteristics at both polarizations.

Generation of a wakefield undulator in plasma with transverse density gradient

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stupakov, Gennady V.

Here, we show that a short relativistic electron beam propagating in a plasma with a density gradient perpendicular to the direction of motion generates a wakefield in which a witness bunch experiences a transverse force. A density gradient oscillating along the beam path would create a periodically varying force$-$an undulator, with an estimated strength of the equivalent magnetic field more than ten Tesla. This opens an avenue for creation of a high-strength, short-period undulators, which eventually may lead to all-plasma, free electron lasers where a plasma wakefield acceleration is naturally combined with a plasma undulator in a unifying, compact setup.

Magnetic force study for the helical afterburner for the European XFEL

NASA Astrophysics Data System (ADS)

Li, Peng; Wei, Tao; Li, Yuhui; Pflueger, Joachim

2017-05-01

At present the SASE3 undulator line at the European XFEL is using a planar undulator producing linear polarized soft Xray radiation only. In order to satisfy the demand for circular polarized radiation a helical undulator system, the so-called afterburner is in construction. It will be operated as a radiator using the pre-bunched beam of the SASE3 undulator system. Among several options for the magnetic structure the Apple-X geometry was chosen. This is a pure permanent magnet undulator using NdFeB material. Four magnet arrays are arranged symmetrically the beam axis. Polarization can be changed by adjusting the phase shift (PS) between the two orthogonal structures. The field strength can be adjusted either by gap adjustment or alternatively by the amplitude shift (AS) scheme. For an engineering design the maximum values of forces and torques on each of the components under worst case operational conditions are important. The superposition principle is used to reduce calculation time. It is found that the maximum forces Fx, Fy and Fz for a 2m long Apple-X undulator are 1.8*104N, 2.4*104N and 2.3*104N, respectively. More results are presented in this paper.

Commissioning of the soft x-ray undulator beamline at the Siam Photon Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Hideki, E-mail: hideki@slri.or.th; Chaichuay, Sarunyu; Sudmuang, Porntip

2016-07-27

The synchrotron radiation from the first undulator at the Siam Photon Laboratory was characterized with the photon beam position monitors (BPMs) and grating monochromator. The soft x-ray undulator beamline employs a varied line-spacing plane grating monochromator with three interchangeable gratings. Since 2010, the beamline has delivered photons with energy of 40-160 and 220-1040 eV at the resolving power of 10,000 for user services at the two end- stations that utilize the photoemission electron spectroscopy and microscopy techniques. The undulator power-density distributions measured by the 0.05-mm wire-scan BPM were in good agreement with those in simulation. The flux-density distributions were evaluatedmore » in the red-shift measurements, which identify the central cone of radiation and its distribution. Since 2014, the operation of the other insertion devices in the storage ring has started, and consequently bought about the increases in the emittance from 41 to 61 nm·rad and the coupling constant from 4 to 11%. The local electron-orbit correction greatly improved the alignment of the electron beam in the undulator section resulting in the improvements of the photon flux and harmonics peaks of the undulator radiation.« less

Geoid undulation computations at laser tracking stations

NASA Technical Reports Server (NTRS)

Despotakis, Vasilios K.

1987-01-01

Geoid undulation computations were performed at 29 laser stations distributed around the world using a combination of terrestrial gravity data within a cap of radius 2 deg and a potential coefficient set up to 180 deg. The traditional methods of Stokes' and Meissl's modification together with the Molodenskii method and the modified Sjoberg method were applied. Performing numerical tests based on global error assumptions regarding the terrestrial data and the geopotential set it was concluded that the modified Sjoberg method is the most accurate and promising technique for geoid undulation computations. The numerical computations for the geoid undulations using all the four methods resulted in agreement with the ellipsoidal minus orthometric value of the undulations on the order of 60 cm or better for most of the laser stations in the eastern United States, Australia, Japan, Bermuda, and Europe. A systematic discrepancy of about 2 meters for most of the western United States stations was detected and verified by using two relatively independent data sets. For oceanic laser stations in the western Atlantic and Pacific oceans that have no terrestrial data available, the adjusted GEOS-3 and SEASAT altimeter data were used for the computation of the geoid undulation in a collocation method.

The Tribology of Undulated Surfaces

DTIC Science & Technology

1989-05-30

wear, in effect by decreasing the impact of plowing. Lubrication, hard coatings, fiber-reinforced composites are but a few examples. All these methods ha...In addition, the effects of pad width and cavity volume fraction of the undulated surface were also investigated. A plowing model proposed for...boundary lubricated sliding is in good agreement with experimental results. It is suggested, furthermore, that the undulated surfaces provide an effective

Global accuracy estimates of point and mean undulation differences obtained from gravity disturbances, gravity anomalies and potential coefficients

NASA Technical Reports Server (NTRS)

Jekeli, C.

1979-01-01

Through the method of truncation functions, the oceanic geoid undulation is divided into two constituents: an inner zone contribution expressed as an integral of surface gravity disturbances over a spherical cap; and an outer zone contribution derived from a finite set of potential harmonic coefficients. Global, average error estimates are formulated for undulation differences, thereby providing accuracies for a relative geoid. The error analysis focuses on the outer zone contribution for which the potential coefficient errors are modeled. The method of computing undulations based on gravity disturbance data for the inner zone is compared to the similar, conventional method which presupposes gravity anomaly data within this zone.

Physical mechanism for flat-to-lenticular lens conversion in homogeneous liquid crystal cell with periodically undulated electrode.

PubMed

Na, Jun-Hee; Park, Seung Chul; Kim, Se-Um; Choi, Yoonseuk; Lee, Sin-Doo

2012-01-16

A convertible lenticular liquid crystal (LC) lens architecture is demonstrated using an index-matched planarization layer on a periodically undulated electrode for the homogeneous alignment of an LC. It is found that the in-plane component of the electric field by the undulated electrode plays a primary role in the flat-to-lens effect while the out-of-plane component contributes to the anchoring enhancement of the LC molecules in the surface layer. Our LC device having an index-matched planarization layer on the undulated electrode is capable of achieving the electrical tunability from the flat surface to the lenticular lens suitable for 2D/3D convertible displays.

Development and operating experience of a 1.1-m-long superconducting undulator at the Advanced Photon Source

NASA Astrophysics Data System (ADS)

Ivanyushenkov, Y.; Harkay, K.; Borland, M.; Dejus, R.; Dooling, J.; Doose, C.; Emery, L.; Fuerst, J.; Gagliano, J.; Hasse, Q.; Kasa, M.; Kenesei, P.; Sajaev, V.; Schroeder, K.; Sereno, N.; Shastri, S.; Shiroyanagi, Y.; Skiadopoulos, D.; Smith, M.; Sun, X.; Trakhtenberg, E.; Xiao, A.; Zholents, A.; Gluskin, E.

2017-10-01

Development of superconducting undulators continues at the Advanced Photon Source (APS). Two years after successful installation and commissioning of the first relatively short superconducting undulator "SCU0" in Sector 6 of the APS storage ring, the second 1.1-m-long superconducting undulator "SCU1" was installed in Sector 1 of the APS. The device has been in user operation since its commissioning in May 2015. This paper describes the magnetic and cryogenic design of the SCU1 together with the results of stand-alone cold tests. The SCU1's magnetic and cryogenic performance as well as its operating experience in the APS storage ring are also presented.

Undulator radiation from laser-plasma-accelerated electron beams

NASA Astrophysics Data System (ADS)

Shaw, B.; van Tilborg, J.; Gonsalves, A.; Nakamura, K.; Sokollik, T.; Shiraishi, S.; Mittal, R.; Esarey, E.; Schroeder, C.; Toth, C.; Leemans, W. P.

2012-12-01

Recent experiments coupled electron beams from the LOASIS TREX laser plasma accelerator (LPA) [1, 2, 3] to the Tapered Hybrid Undulator (THUNDER). Using the 1.5m, 66 period undulator, followed by an XUV spectrometer, spontaneous radiation was observed at photon energies extending to 100 eV. Previous experiments have reported visible [4] and soft-x-ray [5] radiation. The purpose of our experiments is to do highly precise, single shot diagnostics of the energy spread and emittance for each electron beam. We present recent results including measurements of electron beam transport through the undulator with and without the use of permanent magnetic quadrapoles, and measurements of XUV spectra up to 100 eV from LPA produced e-beams.

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring

DOE PAGES

Tanabe, Toshiya; Bassan, Harmanpreet; Broadbent, Andrew; ...

2017-08-01

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS-II ring,more » the transition region was redesigned. The control system was also updated to NSLS-II specifications. As a result, this paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.« less

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanabe, Toshiya; Bassan, Harmanpreet; Broadbent, Andrew

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS-II ring,more » the transition region was redesigned. The control system was also updated to NSLS-II specifications. As a result, this paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.« less

Algorithms to automate gap-dependent integral tuning for the 2.8-meter long horizontal field undulator with a dynamic force compensation mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Joseph Z., E-mail: x@anl.gov; Vasserman, Isaac; Strelnikov, Nikita

2016-07-27

A 2.8-meter long horizontal field prototype undulator with a dynamic force compensation mechanism has been developed and tested at the Advanced Photon Source (APS) at Argonne National Laboratory (Argonne). The magnetic tuning of the undulator integrals has been automated and accomplished by applying magnetic shims. A detailed description of the algorithms and performance is reported.

Earth's Magnetic Field Measurements for the LCLS Undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hacker, Kirsten

2010-12-13

Measurements of the earth's magnetic field at several locations at SLAC were conducted to determine the possible field error contribution from tuning the undulators in a location with a different magnetic field than that which will be found in the undulator hall. An average difference of 0.08 {+-} 0.04 Gauss has been measured between the downward earth's field components in the test facility and SLAC tunnel locations.

Fast pulsed excitation wiggler or undulator

DOEpatents

van Steenbergen, Arie

1990-01-01

A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

Swimming Dynamics of the Lyme Disease Spirochete

NASA Astrophysics Data System (ADS)

Vig, Dhruv K.; Wolgemuth, Charles W.

2012-11-01

The Lyme disease spirochete, Borrelia burgdorferi, swims by undulating its cell body in the form of a traveling flat wave, a process driven by rotating internal flagella. We study B. burgdorferi’s swimming by treating the cell body and flagella as linearly elastic filaments. The dynamics of the cell are then determined from the balance between elastic and resistive forces and moments. We find that planar, traveling waves only exist when the flagella are effectively anchored at both ends of the bacterium and that these traveling flat waves rotate as they undulate. The model predicts how the undulation frequency is related to the torque from the flagellar motors and how the stiffness of the cell body and flagella affect the undulations and morphology.

The Tapered Hybrid Undulator (THUNDER) of the visible free-electron laser oscillator experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, K.E.; Quimby, D.C.; Slater, J.M.

A 5 m tapered hybrid undulator (THUNDER) has been designed and built as part of the Boeing Aerospace Company and Spectra Technology, Inc. visible free-electron laser (FEL) oscillator experiment. The performance goals required of an undulator for a visible oscillator with large extraction are ambitious. They require the establishment of stringent magnetic field quality tolerances which impact design and fabrication techniques. The performance goals of THUNDER are presented. The tolerances resulting from the FEL interaction are contrasted and compared to those of a synchrotron radiation source. The design, fabrication, and field measurements are discussed. The performance of THUNDER serves asmore » a benchmark for future wiggler/undulator design for advanced FEL's and synchrotron radiation sources.« less

Swimming dynamics of the lyme disease spirochete.

PubMed

Vig, Dhruv K; Wolgemuth, Charles W

2012-11-21

The Lyme disease spirochete, Borrelia burgdorferi, swims by undulating its cell body in the form of a traveling flat wave, a process driven by rotating internal flagella. We study B. burgdorferi's swimming by treating the cell body and flagella as linearly elastic filaments. The dynamics of the cell are then determined from the balance between elastic and resistive forces and moments. We find that planar, traveling waves only exist when the flagella are effectively anchored at both ends of the bacterium and that these traveling flat waves rotate as they undulate. The model predicts how the undulation frequency is related to the torque from the flagellar motors and how the stiffness of the cell body and flagella affect the undulations and morphology.

DOE Office of Scientific and Technical Information (OSTI.GOV)

RAKOWKSY,G.; ASPENLEITER,J.; SOLOMON,L.

The Visible-Infrared SASE Amplifier (VISA) undulator is an in-vacuum, 4-meter long, 1.8 cm period, pure-permanent magnet device, with a novel, strong focusing, permanent magnet FODO array included within the fixed, 6 mm undulator gap. The undulator magnet is constructed of 99-cm long segments, joined into a continuous structure. To attain maximum SASE gain requites establishing overlap of electron and photon beams to within 50 microns rms. This imposes challenging tolerances on mechanical fabrication and magnetic field quality, and necessitates use of laser straightness interferometry for calibration and alignment of the magnetic axes of the undulator segments. This paper describes themore » computerized magnet sorting, pulsed-wire magnetic measurements, trajectory shimming and magnetic axis calibration performed to meet this goal.« less

Three-dimensional, time-dependent simulation of free-electron lasers with planar, helical, and elliptical undulators

NASA Astrophysics Data System (ADS)

Freund, H. P.; van der Slot, P. J. M.; Grimminck, D. L. A. G.; Setija, I. D.; Falgari, P.

2017-02-01

Free-electron lasers (FELs) have been built ranging in wavelength from long-wavelength oscillators using partial wave guiding through ultraviolet through hard x-ray that are either seeded or start from noise. In addition, FELs that produce different polarizations of the output radiation ranging from linear through elliptic to circular polarization are currently under study. In this paper, we develop a three-dimensional, time-dependent formulation that is capable of modeling this large variety of FEL configurations including different polarizations. We employ a modal expansion for the optical field, i.e., a Gaussian expansion with variable polarization for free-space propagation. This formulation uses the full Newton-Lorentz force equations to track the particles through the optical and magnetostatic fields. As a result, arbitrary three-dimensional representations for different undulator configurations are implemented, including planar, helical, and elliptical undulators. In particular, we present an analytic model of an APPLE-II undulator to treat arbitrary elliptical polarizations, which is used to treat general elliptical polarizations. To model oscillator configurations, and allow propagation of the optical field outside the undulator and interact with optical elements, we link the FEL simulation with the optical propagation code OPC. We present simulations using the APPLE-II undulator model to produce elliptically polarized output radiation, and present a detailed comparison with recent experiments using a tapered undulator configuration at the Linac Coherent Light Source. Validation of the nonlinear formation is also shown by comparison with experimental results obtained in the Sorgente Pulsata Auto-amplificata di Radiazione Coerente SASE FEL experiment at ENEA Frascati, a seeded tapered amplifier experiment at Brookhaven National Laboratory, and the 10 kW upgrade oscillator experiment at the Thomas Jefferson National Accelerator Facility.

Beamline front end for in-vacuum short period undulator at the photon factory storage ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyauchi, Hiroshi, E-mail: hiroshi.miyauchi@kek.jp; Department of Accelerator Science, School of High Energy Accelerator Science, SOKENDAI; Tahara, Toshihiro, E-mail: ttahara@post.kek.jp

The straight-section upgrade project of the Photon Factory created four new short straight sections capable of housing in-vacuum short period undulators. The first to fourth short period undulators SGU#17, SGU#03, SGU#01 and SGU#15 were installed at the 2.5-GeV Photon Factory storage ring in 2005, 2006, 2009 and 2013, respectively. The beamline front end for SGU#15 is described in this paper.

PEP as a synchrotron radiation source (invited)

NASA Astrophysics Data System (ADS)

Bienenstock, A.; Brown, G.; Wiedemann, H.; Winick, H.

1989-07-01

The 16-GeV storage ring PEP has characteristics which enable it to operate in modes with very low emittance and to accommodate very long undulators, producing synchrotron radiation at x-ray wavelengths with extremely high brightness and coherent power. Two beamlines, each illuminated by a 2-m long, 77-mm period undulator magnet, are now operational and others are planned. In parasitic operation during colliding-beam runs at 14.5 GeV, these beamlines provide photons above 10 keV with a peak brightness of about 1016 photons/(s mm2 mrad2 ) within a 0.1% bandwidth. In low-emittance tests at 7.1 GeV, horizontal emittances of about 5 nm rad were measured, which is about the same as that planned for the new third-generation x-ray sources. With a current of 15 mA at 7.1 GeV, the present undulators deliver photon beams from 2.7 to 14 keV with a peak brightness of about 1017 . Higher performance levels are expected with the implementation of longer undulators and shorter period undulators. In the longer term, because of its large circumference and long straight sections, PEP could be further developed to achieve even higher performance levels with an emittance below 1 nm rad, very long undulators and picosecond bunches, resulting in one to two orders of magnitude higher brightness and coherent power.

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

DOE PAGES

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan; ...

2017-12-18

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulatormore » tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (~10 % ) provides effective suppression of the sideband instability in the postsaturation regime.« less

Sideband instability analysis based on a one-dimensional high-gain free electron laser model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Cheng-Ying; Wu, Juhao; Yang, Chuan

When an untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. The FEL radiation power or efficiency can be increased by undulator tapering. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation where the FEL power growth stops even with a tapered undulator system. The sideband instability is one of the primary reasons leading to this second saturation. In this paper, we provide a quantitative analysis on how the gradient of undulatormore » tapering can mitigate the sideband growth. The study is carried out semianalytically and compared with one-dimensional numerical simulations. The physical parameters are taken from Linac Coherent Light Source-like electron bunch and undulator systems. The sideband field gain and the evolution of the radiation spectra for different gradients of undulator tapering are examined. It is found that a strong undulator tapering (~10 % ) provides effective suppression of the sideband instability in the postsaturation regime.« less

Development and operating experience of a 1.1-m-long superconducting undulator at the Advanced Photon Source

DOE PAGES

Ivanyushenkov, Y.; Harkay, K.; Borland, M.; ...

2017-10-03

Development of superconducting undulators continues at the Advanced Photon Source (APS). Two years after successful installation and commissioning of the first relatively short superconducting undulator “SCU0” in Sector 6 of the APS storage ring, the second 1.1-m long superconducting undulator “SCU1” was installed in Sector 1 of the APS. The device has been in user operation since its commissioning in May 2015. This paper describes the magnetic and cryogenic design of the SCU1 together with the results of stand-alone cold tests. The SCU1’s magnetic and cryogenic performance as well as its operating experience in the APS storage ring are alsomore » presented.« less

Development and operating experience of a 1.1-m-long superconducting undulator at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanyushenkov, Y.; Harkay, K.; Borland, M.

Development of superconducting undulators continues at the Advanced Photon Source (APS). Two years after successful installation and commissioning of the first relatively short superconducting undulator “SCU0” in Sector 6 of the APS storage ring, the second 1.1-m long superconducting undulator “SCU1” was installed in Sector 1 of the APS. The device has been in user operation since its commissioning in May 2015. This paper describes the magnetic and cryogenic design of the SCU1 together with the results of stand-alone cold tests. The SCU1’s magnetic and cryogenic performance as well as its operating experience in the APS storage ring are alsomore » presented.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gluskin, Efim; Trakhtenberg, Emil; Xu, Joseph Z.

A method and apparatus for implementing dynamic compensation of magnetic forces for undulators are provided. An undulator includes a respective set of magnet arrays, each attached to a strongback, and placed on horizontal slides and positioned parallel relative to each other with a predetermined gap. Magnetic forces are compensated by a set of compensation springs placed along the strongback. The compensation springs are conical springs having exponential-force characteristics that substantially match undulator magnetic forces independently of the predetermined gap. The conical springs are positioned along the length of the magnets.

Design and Fabrication of Soft Morphing Ray Propulsor: Undulator and Oscillator.

PubMed

Kim, Hyung-Soo; Lee, Jang-Yeob; Chu, Won-Shik; Ahn, Sung-Hoon

2017-03-01

A soft morphing ray propulsor capable of generating an undulating motion in its pectoral fins was designed and fabricated. The propulsor used shape memory alloy for actuation, and the body was made with soft polymers. To determine the effects of undulation in the fins, two models that differed in terms of the presence of undulation were fabricated using different polymer materials. The experimental models were tested with a dynamometer to measure and compare thrust tendencies. Thrust measurements were conducted with various fin beat frequencies. Using the experimental data, the concept of an optimized standalone version of the ray robot was suggested and its prototype was fabricated. The fabricated robot was able to swim as fast as 0.26 body length per second and 38% more efficient than other smart material-based ray-like underwater robots.

An undulator based soft x-ray source for microscopy on the Duke electron storage ring

NASA Astrophysics Data System (ADS)

Johnson, Lewis Elgin

1998-09-01

This dissertation describes the design, development, and installation of an undulator-based soft x-ray source on the Duke Free Electron Laser laboratory electron storage ring. Insertion device and soft x-ray beamline physics and technology are all discussed in detail. The Duke/NIST undulator is a 3.64-m long hybrid design constructed by the Brobeck Division of Maxwell Laboratories. Originally built for an FEL project at the National Institute of Standards and Technology, the undulator was acquired by Duke in 1992 for use as a soft x-ray source for the FEL laboratory. Initial Hall probe measurements on the magnetic field distribution of the undulator revealed field errors of more than 0.80%. Initial phase errors for the device were more than 11 degrees. Through a series of in situ and off-line measurements and modifications we have re-tuned the magnet field structure of the device to produce strong spectral characteristics through the 5th harmonic. A low operating K has served to reduce the effects of magnetic field errors on the harmonic spectral content. Although rms field errors remained at 0.75%, we succeeded in reducing phase errors to less than 5 degrees. Using trajectory simulations from magnetic field data, we have computed the spectral output given the interaction of the Duke storage ring electron beam and the NIST undulator. Driven by a series of concerns and constraints over maximum utility, personnel safety and funding, we have also constructed a unique front end beamline for the undulator. The front end has been designed for maximum throughput of the 1st harmonic around 40A in its standard mode of operation. The front end has an alternative mode of operation which transmits the 3rd and 5th harmonics. This compact system also allows for the extraction of some of the bend magnet produced synchrotron and transition radiation from the storage ring. As with any well designed front end system, it also provides excellent protection to personnel and to the storage ring. A diagnostic beamline consisting of a transmission grating spectrometer and scanning wire beam profile monitor was constructed to measure the spatial and spectral characteristics of the undulator radiation. Test of the system with a circulating electron beam has confirmed the magnetic and focusing properties of the undulator, and verified that it can be used without perturbing the orbit of the beam.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couprie, M. E.; Benabderrahmane, C.; Berteaud, P.

The SOLEIL storage ring presents a very high fraction of its circumference dedicated to accommodate Insertion Devices (ID). Over the 25 presently planned insertion devices presenting a large variety of systems, 16 have been already installed and commissioned in September 2009. The UV-VUV region is covered with electromagnetic devices, offering tuneable polarisations. An electromagnet/permanent magnet undulator using copper sheets coils for fast switching of the helicity is under construction. 13 APPLE-II type undulators, with period ranging from 80 down to 36 mm, provide photons in the 0.1-10 keV region, some of them featuring tapering or quasi-periodicity. Five U20 in vacuummore » undulators cover typically the 3-30 keV range whereas an in vacuum wiggler, with compensation of the magnetic forces via adequate springs will cover the 10-50 keV spectral domain. R and D on cryogenic in-vacuum undulator is also under progress. A magnetic chicane using permanent magnet dipoles has also been designed in order to accommodate two canted undulators on the same straight section. A wiggler dedicated to slicing (production of femto second long pulses) is also being designed, its radiation will also serve for an X-ray beamline.« less

Undulator Radiation Damage Experience at LCLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nuhn, H. D.; Field, C.; Mao, S.

2015-01-06

The SLAC National Accelerator Laboratory has been running the Linac Coherent Light Source (LCLS), the first x-ray Free Electron Laser since 2009. Undulator magnet damage from radiation, produced by the electron beam traveling through the 133-m long straight vacuum tube, has been and is a concern. A damage measurement experiment has been performed in 2007 in order to obtain dose versus damage calibrations. Radiation reduction and detection devices have been integrated into the LCLS undulator system. The accumulated radiation dose rate was continuously monitored and recorded. In addition, undulator segments have been routinely removed from the beamline to be checkedmore » for magnetic (50 ppm, rms) and mechanic (about 0.25 µm, rms) changes. A reduction in strength of the undulator segments is being observed, at a level, which is now clearly above the noise. Recently, potential sources for the observed integrated radiation levels have been investigated. The paper discusses the results of these investigation as well as comparison between observed damage and measured dose accumulations and discusses, briefly, strategies for the new LCLS-II upgrade, which will be operating at more than 300 times larger beam rate.« less

Curvature-undulation coupling as a basis for curvature sensing and generation in bilayer membranes.

PubMed

Bradley, Ryan P; Radhakrishnan, Ravi

2016-08-30

We present coarse-grained molecular dynamics simulations of the epsin N-terminal homology domain interacting with a lipid bilayer and demonstrate a rigorous theoretical formalism and analysis method for computing the induced curvature field in varying concentrations of the protein in the dilute limit. Our theory is based on the description of the height-height undulation spectrum in the presence of a curvature field. We formulated an objective function to compare the acquired undulation spectrum from the simulations to that of the theory. We recover the curvature field parameters by minimizing the objective function even in the limit where the protein-induced membrane curvature is of the same order as the amplitude due to thermal undulations. The coupling between curvature and undulations leads to significant predictions: (i) Under dilute conditions, the proteins can sense a site of spontaneous curvature at distances much larger than their size; (ii) as the density of proteins increases the coupling focuses and stabilizes the curvature field to the site of the proteins; and (iii) the mapping of the protein localization and the induction of a stable curvature is a cooperative process that can be described through a Hill function.

Curvature–undulation coupling as a basis for curvature sensing and generation in bilayer membranes

PubMed Central

Bradley, Ryan P.; Radhakrishnan, Ravi

2016-01-01

We present coarse-grained molecular dynamics simulations of the epsin N-terminal homology domain interacting with a lipid bilayer and demonstrate a rigorous theoretical formalism and analysis method for computing the induced curvature field in varying concentrations of the protein in the dilute limit. Our theory is based on the description of the height–height undulation spectrum in the presence of a curvature field. We formulated an objective function to compare the acquired undulation spectrum from the simulations to that of the theory. We recover the curvature field parameters by minimizing the objective function even in the limit where the protein-induced membrane curvature is of the same order as the amplitude due to thermal undulations. The coupling between curvature and undulations leads to significant predictions: (i) Under dilute conditions, the proteins can sense a site of spontaneous curvature at distances much larger than their size; (ii) as the density of proteins increases the coupling focuses and stabilizes the curvature field to the site of the proteins; and (iii) the mapping of the protein localization and the induction of a stable curvature is a cooperative process that can be described through a Hill function. PMID:27531962

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahrdt, J.; Follath, R.; Frentrup, W.

Reflections in synchrotron radiation beam lines tend to change the state of polarization of the radiation. This effect is more pronounced for steep angle of incidence, i.e. at low photon energy (say below 100 eV) beam lines. The APPLE II undulator UE112 at BESSY has all four magnetic rows shiftable and thus generates any state of polarization. To provide any intended polarization state at the sample we perform polarization measurements based on simple and fast linear polarization analysis that together with calculations of the undulator radiation predicts undulator settings that cancel beam line polarization effects.

Light Optics for Optical Stochastic Cooling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andorf, Matthew; Lebedev, Valeri; Piot, Philippe

2016-06-01

In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.

The Advanced Light Source (ALS) Slicing Undulator Beamline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heimann, P. A.; Glover, T. E.; Plate, D.

2007-01-19

A beamline optimized for the bunch slicing technique has been construction at the Advanced Light Source (ALS). This beamline includes an in-vacuum undulator, soft and hard x-ray beamlines and a femtosecond laser system. The soft x-ray beamline may operate in spectrometer mode, where an entire absorption spectrum is accumulated at one time, or in monochromator mode. The femtosecond laser system has a high repetition rate of 20 kHz to improve the average slicing flux. The performance of the soft x-ray branch of the ALS slicing undulator beamline will be presented.

Characterization of undulator radiation at the photon factory

NASA Astrophysics Data System (ADS)

Maezawa, Hideki; Suzuki, Yoshio; Kitamura, Hideo; Sasaki, Taizo

1986-05-01

Spectra of undulator radiation of the Photon Factory undulator, model PMU-2, were measured in a scale of absolute brightness in the soft X-ray region for various values of the K-parameter from 0.72 to 1.66. A significant reduction of the peak brightness was observed, whereas we also observed a relatively sharp edge at the high energy side of the first harmonic. The results show that the peak brightness and the band width are highly dependent on the beam parameters and the geometry of spectral observation.

A compact high brightness laser synchrotron light source for medical applications

NASA Astrophysics Data System (ADS)

Nakajima, Kazuhisa

1999-07-01

The present high-brightness hard X-ray sources have been developed as third generation synchrotron light sources based on large high energy electron storage rings and magnetic undulators. Recently availability of compact terawatt lasers arouses a great interest in the use of lasers as undulators. The laser undulator concept makes it possible to construct an attractive compact synchrotron radiation source which has been proposed as a laser synchrotron light source. This paper proposes a compact laser synchrotron light source for mediacal applications, such as an intravenous coronary angiography and microbeam therapy.

An Undulator-Based Laser Wakefield Accelerator Electron Beam Diagnostic

NASA Astrophysics Data System (ADS)

Bakeman, Michael S.

Currently particle accelerators such as the Large Hadron Collider use RF cavities with a maximum field gradient of 50-100 MV/m to accelerate particles over long distances. A new type of plasma based accelerator called a Laser Plasma Accelerator (LPA) is being investigated at the LOASIS group at Lawrence Berkeley National Laboratory which can sustain field gradients of 10-100 GV/m. This new type of accelerator offers the potential to create compact high energy accelerators and light sources. In order to investigate the feasibility of producing a compact light source an undulator-based electron beam diagnostic for use on the LOASIS LPA has been built and calibrated. This diagnostic relies on the principal that the spectral analysis of synchrotron radiation from an undulator can reveal properties of the electron beam such as emittance, energy and energy spread. The effects of electron beam energy spread upon the harmonics of undulator produced synchrotron radiation were derived from the equations of motion of the beam and numerically simulated. The diagnostic consists of quadrupole focusing magnets to collimate the electron beam, a 1.5 m long undulator to produce the synchrotron radiation, and a high resolution high gain XUV spectrometer to analyze the radiation. The undulator was aligned and tuned in order to maximize the flux of synchrotron radiation produced. The spectrometer was calibrated at the Advanced Light Source, with the results showing the ability to measure electron beam energy spreads at resolutions as low as 0.1% rms, a major improvement over conventional magnetic spectrometers. Numerical simulations show the ability to measure energy spreads on realistic LPA produced electron beams as well as the improvements in measurements made with the quadrupole magnets. Experimentally the quadrupoles were shown to stabilize and focus the electron beams at specific energies for their insertion into the undulator, with the eventual hope of producing an all optical Free Electron Laser operating in the XUV and soft x-ray regimes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesgin, Ibrahim; Kasa, Matthew; Ivanyushenkov, Yury

Here, this paper presents test results on a prototype superconducting undulator magnet fabricated using 15% Zr-doped rare-earth barium copper oxide high temperature superconducting (HTS) tapes. On an 11-pole magnet we demonstrate an engineering current density, J e, of more than 2.1 kA mm -2 at 4.2 K, a value that is 40% higher than reached in comparable devices wound with NbTi-wire, which is used in all currently operating superconducting undulators. A novel winding scheme enabling the continuous winding of tape-shaped conductors into the intricate undulator magnets as well as a partial interlayer insulation procedure were essential in reaching this advancemore » in performance. Currently, there are rapid advances in the performance of HTS; therefore, achieving even higher current densities in an undulator structure or/and operating it at temperatures higher than 4.2 K will be possible, which would substantially simplify the cryogenic design and reduce overall costs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanyushenkov, Y.; Doose, C.; Fuerst, J.

Development of superconducting undulator (SCU) technology continues at the Advanced Photon Source (APS). The experience of building and successful operating the first short-length, 16-mm period length superconducting undulator SCU0 paved the way for a 1-m long, 18-mm period device— SCU18-1— which has been in operation since May 2015. The APS SCU team has also built and tested a 1.5-m long, 21-mm period length undulator as a part of the LCLS SCU R&D program, aimed at demonstration of SCU technology availability for free electron lasers. This undulator successfully achieved all the requirements including a phase error of 5° RMS. Our teammore » has recently completed one more 1-m long, 18-mm period length undulator— SCU18-2— that is replacing the SCU0. We are also working on a helical SCU for the APS. The status of these projects will be presented.« less

Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hidaka, Y.; She, Y.; Murphy, J.B.

2011-03-28

We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high-gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering. We have performed first experiments with a tapered undulator and amore » short seed laser pulse. Pulse broadening with tapering expected from simulations was experimentally confirmed. However, the experimentally obtained spectra degraded with tapering, whereas the simulations predicted improvement. A further numerical study is under way to resolve this issue.« less

Wave-optics modeling of the optical-transport line for passive optical stochastic cooling

NASA Astrophysics Data System (ADS)

Andorf, M. B.; Lebedev, V. A.; Piot, P.; Ruan, J.

2018-03-01

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsystemcritical to the OSC scheme is the focusing optics used to image radiation from the upstream "pickup" undulator to the downstream "kicker" undulator. In this paper, we present simulation results using wave-optics calculation carried out with the SYNCHROTRON RADIATION WORKSHOP (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrable Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.

3D theory of a high-gain free-electron laser based on a transverse gradient undulator

NASA Astrophysics Data System (ADS)

Baxevanis, Panagiotis; Ding, Yuantao; Huang, Zhirong; Ruth, Ronald

2014-02-01

The performance of a free-electron laser (FEL) depends significantly on the various parameters of the driving electron beam. In particular, a large energy spread in the beam results in a substantial reduction of the FEL gain, an effect which is especially relevant when one considers FELs driven by plasma accelerators or ultimate storage rings. For such cases, one possible solution is to use a transverse gradient undulator (TGU). In this concept, the energy spread problem is mitigated by properly dispersing the electron beam and introducing a linear, transverse field dependence in the undulator. This paper presents a self-consistent theoretical analysis of a TGU-based, high-gain FEL which takes into account three-dimensional (3D) effects, including beam size variations along the undulator. The results of our theory compare favorably with simulation and are used in fast optimization studies of various x-ray FEL configurations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andorf, M. B.; Lebedev, V. A.; Piot, P.

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsystemcritical to the OSC scheme is the focusing optics used to image radiation from the upstream “pickup” undulator to the downstream “kicker” undulator. In this paper, we present simulation results using wave-optics calculation carried out with the Synchrotron Radiation Workshop (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrablemore » Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.« less

Undulator performance on PEP storage ring with different optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shenoy, G.K.; Viccaro, P.J.; Alp, E.E.

1987-12-01

Our ability to profitably utilize the radiation from undulators proposed for PEP is determined by their performance in the different operating modes and by whether the design tolerance required for acceptable operation of the device can be met with available technology. The purpose of this paper is to provide spectral characteristics for some typical devices calculated using a Monte-Carlo algorithm in which the Lienard-Wiechert potential is integrated over the trajectory of the charged particle along the undulator length. The actual emittance of the particle beam for the various PEP operating modes are included explicitly in the simulations. In addition, wemore » have carried out a single partial analysis of the effects of undulator magnetic field errors on the spectral properties in order to estimate the design tolerance requirements necessary for devices which have been proposed PEP. 6 figs.« less

Radiation collimation in a thick crystalline undulator

NASA Astrophysics Data System (ADS)

Wistisen, Tobias Nyholm; Uggerhøj, Ulrik Ingerslev; Hansen, John Lundsgaard; Lauth, Werner; Klag, Pascal

2017-05-01

With the recent experimental confirmation of the existence of energetic radiation from a Small Amplitude, Small Period (SASP) crystalline undulator [T.N. Wistisen, K.K. Andersen, S. Yilmaz, R. Mikkelsen, J. Lundsgaard Hansen, U.I. Uggerhøj, W. Lauth, H. Backe, Phys. Rev. Lett. 112, 254801 (2014)], the field of specially manufactured crystals, from which specific radiation characteristics can be obtained, has evolved substantially. In this paper we confirm the existence of the crystalline undulator radiation, using electrons of energies of 855 GeV from the MAinzer MIcrotron (MAMI) in a crystal that is approximately 10 times thicker than the previous one. Furthermore, we have measured a significant increase in enhancement, in good agreement with calculations, of the undulator peak by collimation to angles smaller than the natural opening angle of the radiation emission process, 1 /γ. Contribution to the Topical Issue: "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

Volumetric PIV of multiple free-swimming maneuvers generated by the KnifeBot: a biomimetic vessel propelled by an undulating fin

NASA Astrophysics Data System (ADS)

Liu, Hanlin; Troolin, Daniel; Hortensius, Ruben; Pothos, Stamatios; Curet, Oscar

2017-11-01

An undulating fin represents a remarkable propulsion model for underwater vehicles due to its high propulsive efficiency and considerable locomotor capabilities. In this work, we used a bio-inspired vessel, the KnifeBot to demonstrate the maneuverability of undulating fin propulsion, including forward-backward swimming, station keeping and vertical swimming. This self-contained robotic system uses an undulating ventral fin as the propulsor and features a slender 3D-printed hull with 16 motors, 2 batteries and electronic boards encapsulated inside. We tested the robot in a water-filled tank and used volumetric particle image velocimetry (V3V PIV) to investigate the three-dimensional flow features and vortex structures generated by the undulating ribbon fin in free-swimming maneuvers. Our results indicate that in the forward swimming, a series of vortex tubes are shed off the fin edge. A streamwise jet at an oblique angle to the fin is generated in association with the vortex tubes propelling the robot forward as well as pitching it up. For the hovering maneuver with inward counter-propagating waves. The streamlines develop vertically downward with the tip vortex shed from the fin edge. This downward jet provides substantial heave force for the robot to swim upward or perform station keeping. Our findings will be useful for understanding the mechanical basis of undulating fin propulsion and facilitate the development of bio-inspired vehicles using undulatory propellers. Office of Naval Research under Award Number N00014-16-1-2505.

Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakeman, M. S.; University of Nevada Reno, Reno, NV 89557; Van Tilborg, J.

The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.

High Efficiency Electron-Laser Interactions in Tapered Helical Undulators

NASA Astrophysics Data System (ADS)

Duris, Joseph Patrick

Efficient coupling of relativistic electron beams with high power radiation lies at the heart of advanced accelerator and light source research and development. The inverse free electron laser is a stable accelerator capable of harnessing very high intensity laser electric fields to efficiently transfer large powers from lasers to electron beams. In this dissertation, we first present the theoretical framework to describe the interaction, and then apply our improved understanding of the IFEL to the design and numerical study of meter-long, GeV IFELs for compact light sources. The central experimental work of the dissertation is the UCLA BNL helical inverse free electron laser experiment at the Accelerator Test Facility in Brookhaven National Laboratory which used a strongly tapered 54cm long, helical, permanent magnet undulator and a several hundred GW CO2 laser to accelerate electrons from 52 to 106MeV, setting new records for inverse free electron laser energy gain (54MeV) and average accelerating gradient (100MeV/m). The undulator design and fabrication as well as experimental diagnostics are presented. In order to improve the stability and quality of the accelerated electron beam, we redesigned the undulator for a slightly reduced output energy by modifying the magnet gap throughout the undulator, and we used this modified undulator to demonstrated capture of >25% of the injected beam without prebunching. In the study of heavily loaded GeV inverse free electron lasers, we show that a majority of the power may be transferred from a laser to the accelerated electron beam. Reversing the process to decelerate high power electron beams, a mechanism we refer to as tapering enhanced stimulated superradiant amplification, offers a clear path to high power light sources. We present studies of radiation production for a wide range of wavelengths (10mum, 13nm, and 0.3nm) using this method and discuss the design for a deceleration experiment using the same undulator used for acceleration in this experiment. By accounting for the evolving radiation field in the design of the undulator tapering, a large fraction of energy may be transferred between the electrons and laser, enabling compact, high-current GeV accelerators and various wavelength light-sources of unprecedented peak powers.

Variable-Period Undulators For Synchrotron Radiation

DOEpatents

Shenoy, Gopal; Lewellen, John; Shu, Deming; Vinokurov, Nikolai

2005-02-22

A new and improved undulator design is provided that enables a variable period length for the production of synchrotron radiation from both medium-energy and high-energy storage rings. The variable period length is achieved using a staggered array of pole pieces made up of high permeability material, permanent magnet material, or an electromagnetic structure. The pole pieces are separated by a variable width space. The sum of the variable width space and the pole width would therefore define the period of the undulator. Features and advantages of the invention include broad photon energy tunability, constant power operation and constant brilliance operation.

Micropole Undulators In Synchrotron Radiation Technology: Design And Construction Of A Submillimeter Period Prototype With A 3 Kilogauss Peak Field At SSRL

NASA Astrophysics Data System (ADS)

Tatchyn, Roman; Csonka, Paul

1986-01-01

The availability of undulators with submillimeter periods will profoundly affect the future development of soft x-ray sources and their attendant instrumentation. Outputs comparable to those of present-day conventional undulators, obtainable with much lower energy storage rings, is only one promising aspect of such devices. This paper critically examines some of the future prospects of such devices and describes the design and practical construction of a 1" long prototype consisting of 35 periods. A proposed experiment to test this device on a linac is described.

Strong permanent magnet-assisted electromagnetic undulator

DOEpatents

Halbach, Klaus

1988-01-01

This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

A strong permanent magnet-assisted electromagnetic undulator

DOEpatents

Halbach, K.

1987-01-30

This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles. 4 figs.

High Efficiency Energy Extraction from a Relativistic Electron Beam in a Strongly Tapered Undulator

DOE PAGES

Sudar, N.; Musumeci, P.; Duris, J.; ...

2016-10-19

Here we present results of an experiment where, using a 200 GW CO 2 laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.

Progress on the superconducting undulator for ANKA and on the instrumentation for R and D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casalbuoni, Sara; Baumbach, Tilo; Grau, Andreas

2010-06-23

Superconducting undulators show a larger magnetic field strength for the same gap and period length, as compared to permanent magnet devices, which allows to generate X-ray beams of higher brilliance and with harder spectrum. The worldwide first short period length superconducting undulator is in operation since 2005 at the synchrotron light source ANKA in Karlsruhe [1]. To further drive the development in this field a research and development program is being carried out. In this contribution we report on the last progress of the construction of a 1.5 m long superconducting undulator with a period length of 15 mm, plannedmore » to be installed in ANKA beginning 2010 to be the light source of the new beamline NANO for high resolution X-ray scattering. The key specifications of the system are an undulator parameter K higher than 2 (with a magnetic gap of 5 mm) and a phase error smaller than 3.5 degrees. Cryocoolers will keep the coils at 4.2 K for a beam heat load of 4 W. The ongoing R and D includes improvements in understanding of the magnetic field properties and of the beam heat load mechanisms. The tools and instruments under development to fulfill these tasks are also discussed.« less

Progress on the superconducting undulator for ANKA and on the instrumentation for R&D

NASA Astrophysics Data System (ADS)

Casalbuoni, Sara; Baumbach, Tilo; Grau, Andreas; Hagelstein, Michael; de Jauregui, David Saez; Boffo, Cristian; Borlein, Markus; Walter, Wolfgang; Magerl, Andreas; Mashkina, Elena; Vassiljev, Nikita

2010-06-01

Superconducting undulators show a larger magnetic field strength for the same gap and period length, as compared to permanent magnet devices, which allows to generate X-ray beams of higher brilliance and with harder spectrum. The worldwide first short period length superconducting undulator is in operation since 2005 at the synchrotron light source ANKA in Karlsruhe [1]. To further drive the development in this field a research and development program is being carried out. In this contribution we report on the last progress of the construction of a 1.5 m long superconducting undulator with a period length of 15 mm, planned to be installed in ANKA beginning 2010 to be the light source of the new beamline NANO for high resolution X-ray scattering. The key specifications of the system are an undulator parameter K higher than 2 (with a magnetic gap of 5 mm) and a phase error smaller than 3.5 degrees. Cryocoolers will keep the coils at 4.2 K for a beam heat load of 4 W. The ongoing R&D includes improvements in understanding of the magnetic field properties and of the beam heat load mechanisms. The tools and instruments under development to fulfill these tasks are also discussed.

Spatial uncertainty of a geoid undulation model in Guayaquil, Ecuador

NASA Astrophysics Data System (ADS)

Chicaiza, E. G.; Leiva, C. A.; Arranz, J. J.; Buenańo, X. E.

2017-06-01

Geostatistics is a discipline that deals with the statistical analysis of regionalized variables. In this case study, geostatistics is used to estimate geoid undulation in the rural area of Guayaquil town in Ecuador. The geostatistical approach was chosen because the estimation error of prediction map is getting. Open source statistical software R and mainly geoR, gstat and RGeostats libraries were used. Exploratory data analysis (EDA), trend and structural analysis were carried out. An automatic model fitting by Iterative Least Squares and other fitting procedures were employed to fit the variogram. Finally, Kriging using gravity anomaly of Bouguer as external drift and Universal Kriging were used to get a detailed map of geoid undulation. The estimation uncertainty was reached in the interval [-0.5; +0.5] m for errors and a maximum estimation standard deviation of 2 mm in relation with the method of interpolation applied. The error distribution of the geoid undulation map obtained in this study provides a better result than Earth gravitational models publicly available for the study area according the comparison with independent validation points. The main goal of this paper is to confirm the feasibility to use geoid undulations from Global Navigation Satellite Systems and leveling field measurements and geostatistical techniques methods in order to use them in high-accuracy engineering projects.

Triggering for Magnetic Field Measurements of the LCLS Undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hacker, Kirsten

A triggering system for magnetic field measurements of the LCLS undulators has been built with a National Instruments PXI-1002 and a Xylinx FPGA board. The system generates single triggers at specified positions, regardless of encoder sensor jitter about a linear scale.

Wave-Optics Modeling of the Optical-Transport Line for Passive Optical Stochastic Cooling

DOE PAGES

Andorf, M. B.; Lebedev, V. A.; Piot, P.; ...

2018-03-01

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsystemcritical to the OSC scheme is the focusing optics used to image radiation from the upstream “pickup” undulator to the downstream “kicker” undulator. In this paper, we present simulation results using wave-optics calculation carried out with the Synchrotron Radiation Workshop (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrablemore » Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.« less

Collimation study for LCLS

NASA Astrophysics Data System (ADS)

Marin, E.; Raubenhaimer, T.; Welch, J.; White, G.

2017-09-01

In this paper we investigate the power deposition along the undulator section of the SLAC Linac Coherent Light Source (LCLS) due to the primary e--beam but also due to potential secondary particles. The expected beam distribution after the LCLS injector is deliberately broadened as an approximated representation of the beam halo. Secondary particles, as e+, e- and photons, are generated as a result of tracking the intercepted beam through a dense material. This process is carried out by means of GEANT-4, which has been convoluted into our main tracking engine, LUCRETIA. Simulations show no losses along the undulator section when assuming the nominal primary beam and collimator gaps. However when opening the gaps of collimators located at the first collimator section, by 25%, the fattened beam is partially intercepted by the second collimator section, which is aligned to the undulators. Secondary particles, mostly photons generated at the second collimator section, deposit their energy along the undulator section, at a rate of the order of a milliwatt.

Surface-micromachined magnetic undulator with period length between 10μm and 1 mm for advanced light sources

NASA Astrophysics Data System (ADS)

Harrison, Jere; Joshi, Abhijeet; Lake, Jonathan; Candler, Rob; Musumeci, Pietro

2012-07-01

A technological gap exists between the μm-scale wiggling periods achieved using electromagnetic waves of high intensity laser pulses and the mm scale of permanent-magnet and superconducting undulators. In the sub-mm range, surface-micromachined soft-magnetic micro-electro-mechanical system inductors with integrated solenoidal coils have already experimentally demonstrated 100 to 500 mT field amplitude across air gaps as large as 15μm. Simulations indicate that magnetic fields as large as 1.5 T across 50μm inductor gaps are feasible. A simple rearranging of the yoke and pole geometry allows for fabrication of 10+ cm long undulator structures with period lengths between 12.5μm and 1 mm. Such undulators find application both in high average power spontaneous emission sources and, if used in combination with ultrahigh-brightness electron beams, could lead to the realization of low energy compact free-electron lasers. Challenges include electron energy broadening due to wakefields and Joule heating in the electromagnet.

Magnetic assessment and modelling of the Aramis undulator beamline

PubMed Central

Calvi, M.; Camenzuli, C.; Ganter, R.; Sammut, N.; Schmidt, Th.

2018-01-01

Within the SwissFEL project at the Paul Scherrer Institute (PSI), the hard X-ray line (Aramis) has been equipped with short-period in-vacuum undulators, known as the U15 series. The undulator design has been developed within the institute itself, while the prototyping and the series production have been implemented through a close collaboration with a Swiss industrial partner, Max Daetwyler AG, and several subcontractors. The magnetic measurement system has been built at PSI, together with all the data analysis tools. The Hall probe has been designed for PSI by the Swiss company SENIS. In this paper the general concepts of both the mechanical and the magnetic properties of the U15 series of undulators are presented. A description of the magnetic measurement equipment is given and the results of the magnetic measurement campaign are reported. Lastly, the data reduction methods and the associated models are presented and their actual implementation in the control system is detailed. PMID:29714179

Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source

NASA Astrophysics Data System (ADS)

Casalbuoni, S.; Cecilia, A.; Gerstl, S.; Glamann, N.; Grau, A. W.; Holubek, T.; Meuter, C.; de Jauregui, D. Saez; Voutta, R.; Boffo, C.; Gerhard, Th.; Turenne, M.; Walter, W.

2016-11-01

A new cryogen-free full scale (1.5 m long) superconducting undulator with a period length of 15 mm (SCU15) has been successfully tested in the ANKA storage ring. This represents a very important milestone in the development of superconducting undulators for third and fourth generation light sources carried on by the collaboration between the Karlsruhe Institute of Technology and the industrial partner Babcock Noell GmbH. SCU15 is the first full length device worldwide that with beam reaches a higher peak field than what expected with the same geometry (vacuum gap and period length) with an ideal cryogenic permanent magnet undulator built with the best material available PrFeB. After a summary on the design and main parameters of the device, we present here the characterization in terms of spectral properties and the long term operation of the SCU15 in the ANKA storage ring.

Antiaging activity of low molecular weight peptide from Paphia undulate

NASA Astrophysics Data System (ADS)

Chen, Xin; Cai, Bingna; Chen, Hua; Pan, Jianyu; Chen, Deke; Sun, Huili

2013-05-01

Low molecular weight peptide (LMWP) was prepared from clam Paphia undulate and its antiaging effect on D-galactose-induced acute aging in rats, aged Kunming mice, ultraviolet-exposed rats, and thermally injured rats was investigated. P. undulate flesh was homogenized and digested using papain under optimal conditions, then subjected to Sephadex G-25 chromatography to isolate the LMWP. Administration of LMWP significantly reversed D-galactose-induced oxidative stress by increasing the activities of glutathione peroxidase (GPx) and catalase (CAT), and by decreasing the level of malondialdehyde (MDA). This process was accompanied by increased collagen synthesis. The LMWP prevented photoaging and promoted dermis recovery and remission of elastic fiber hyperplasia. Furthermore, treatment with the LMWP helped to regenerate elastic fibers and the collagen network, increased superoxide dismutase (SOD) in the serum and significantly decreased MDA. Thermal scald-induced inflammation and edema were also relieved by the LWMP, while wound healing in skin was promoted. These results suggest that the LMWP from P. undulate could serve as a new antiaging substance in cosmetics.

Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balal, N.; Magory, E.; Bandurkin, I. V.

2015-10-19

It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect ismore » designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.« less

Theory of electromagnetic insertion devices and the corresponding synchrotron radiation

NASA Astrophysics Data System (ADS)

Shumail, Muhammad; Tantawi, Sami G.

2016-07-01

Permanent magnet insertion devices (IDs), which are the main radiation generating devices in synchrotron light sources and free-electron lasers, use a time-invariant but space-periodic magnetic field to wiggle relativistic electrons for short-wavelength radiation generation. Recently, a high power microwave based undulator has also been successfully demonstrated at SLAC which promises the advantage of dynamic tunability of radiation spectrum and polarization. Such IDs employ transverse elecromagnetic fields which are periodic in both space and time to undulate the electrons. In this paper we develop a detailed theory of the principle of electromagnetic IDs from first principles for both linear and circular polarization modes. The electromagnetic equivalent definitions of undulator period (λu) and undulator deflection parameter (K ) are derived. In the inertial frame where the average momentum of the electron is zero, we obtain the figure-8-like trajectory for the linear polarization mode and the circular trajectory for the circular polarization mode. The corresponding radiation spectra and the intensity of harmonics is also calculated.

Development and operating experience of a short-period superconducting undulator at the Advanced Photon Source

DOE PAGES

Ivanyushenkov, Y.; Harkay, K.; Abliz, M.; ...

2015-04-01

In this study, a decade-long effort at the Advanced Photon Source (APS) of Argonne National Laboratory (ANL) on development of superconducting undulators culminated in December 2012 with the installation of the first superconducting undulator “SCU0” into Sector 6 of the APS storage ring. The device was commissioned in January 2013 and has been in user operation since. This paper presents the magnetic and cryogenic design of the SCU0 together with the results of stand-alone cold tests. The initial commissioning and characterization of SCU0 as well as its operating experience in the APS storage ring are described.

Ice Velocity Mapping of Ross Ice Shelf, Antarctica by Matching Surface Undulations Measured by Icesat Laser Altimetry

NASA Technical Reports Server (NTRS)

Lee, Choon-Ki; Han, Shin-Chan; Yu, Jaehyung; Scambos, Ted A.; Seo, Ki-Weon

2012-01-01

We present a novel method for estimating the surface horizontal velocity on ice shelves using laser altimetrydata from the Ice Cloud and land Elevation Satellite (ICESat; 20032009). The method matches undulations measured at crossover points between successive campaigns.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, T.; Imhof, A.; Ingold, G.

To vary the polarization vector of an APPLE II undulator continuously from 0 - 180 deg., all four magnet arrays need to be movable. Following the adjustable-phase undulator approach by R. Carr, a 3.4 m long fixed gap undulator for SLS with a gap of 11.6 mm has been constructed. It will be installed in fall 2006. The gap drive is replaced by a pair-wise shift of the magnet arrays to change the energy, while the polarization is changed by shifts of diagonal arrays. The high injection efficiency and standard operation top-up mode at the SLS allows this simplified undulatormore » design. The design as well as the operational aspects will be discussed.« less

Surface-potential undulation of Alq3 thin films prepared on ITO, Au, and n-Si.

PubMed

Ozasa, Kazunari; Ito, Hiromi; Maeda, Mizuo; Hara, Masahiko

2012-01-01

The surface potential (SP) morphology on thin films of tris(8-hydroxyquinolinato) aluminum (Alq3) was investigated with Kelvin probe force microscopy. Thin Alq3 films of 100 nm were prepared on ITO/glass substrates, Au/mica substrates, and n-Si substrates. Cloud-like morphologies of the SP undulation with 200-400 nm in lateral size were observed for all three types of the substrates. New larger peaks were observed in the cloud-like morphologies when the surfaces were exposed shortly to a light, while the SP average was reduced monotonically. The nonuniform distribution of charged traps and mobility was deduced from the SP undulation morphology and its photoexposure dependences.

Method for the production of wideband THz radiation

DOEpatents

Krafft, Geoffrey A [Newport News, VA

2008-01-01

A method for the production of extremely wide bandwidth THz radiation comprising: delivering an electron beam from a source to an undulator that does not deflect the angle or transversely move the electron beam; and optimizing the undulator to yield peak emission in the middle of the THz band (1 THz). These objectives are accomplished by magnetically bending the orbit of the incoming electron beam in the undulator according to the function x(z)=x.sub.o exp(-z.sup.2/2.sigma..sup.2) and controlling the transverse magnetic field to be B(z)=B.sub.0(1-z.sup.2/.sigma..sup.2)exp(-z.sup.2/2.sigma..sup.2).

Flying radio frequency undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuzikov, S. V.; Vikharev, A. A.; Savilov, A. V.

2014-07-21

A concept for the room-temperature rf undulator, designed to produce coherent X-ray radiation by means of a relatively low-energy electron beam and pulsed mm-wavelength radiation, is proposed. The “flying” undulator is a high-power short rf pulse co-propagating together with a relativistic electron bunch in a helically corrugated waveguide. The electrons wiggle in the rf field of the −1st spatial harmonic with the phase velocity directed in the opposite direction in respect to the bunch velocity, so that particles can irradiate high-frequency Compton's photons. A high group velocity (close to the speed of light) ensures long cooperative motion of the particlesmore » and the co-propagating rf pulse.« less

Micropole undulator

DOEpatents

Tatchyn, Roman O.; Csonka, Paul L.; Cremer, Jay T.

1990-12-11

Micropole undulators for use in the generation of x-rays from moving charged particles are disclosed. Two rows of spaced apart poles are arranged so that each pole produces a magnetic field aligned with all other similar fields. The poles are the ends of "C"-shaped magnets. In each row, adjacent poles are separated by spacers made of a superconducting material.

Microwave and plasma-assisted modification of composite fiber surface topography

DOEpatents

Paulauskas, Felix L [Knoxville, TN; White, Terry L [Knoxville, TN; Bigelow, Timothy S [Knoxville, TN

2003-02-04

The present invention introduces a novel method for producing an undulated surface on composite fibers using plasma technology and microwave radiation. The undulated surface improves the mechanical interlocking of the fibers to composite resins and enhances the mechanical strength and interfacial sheer strength of the composites in which they are introduced.

Evolution of Martian polar landscapes - Interplay of long-term variations in perennial ice cover and dust storm intensity

NASA Technical Reports Server (NTRS)

Cutts, J. A.; Blasius, K. R.; Roberts, W. J.

1979-01-01

The discovery of a new type of Martian polar terrain, called undulating plain, is reported and the evolution of the plains and other areas of the Martian polar region is discussed in terms of the trapping of dust by the perennial ice cover. High-resolution Viking Orbiter 2 observations of the north polar terrain reveal perennially ice-covered surfaces with low relief, wavelike, regularly spaced, parallel ridges and troughs (undulating plains) occupying areas of the polar terrain previously thought to be flat, and associated with troughs of considerable local relief which exhibit at least partial annual melting. It is proposed that the wavelike topography of the undulating plains originates from long-term periodic variations in cyclical dust precipitation at the margin of a growing or receding perennial polar cap in response to changes in insolation. The troughs are proposed to originate from areas of steep slope in the undulating terrain which have lost their perennial ice cover and have become incapable of trapping dust. The polar landscape thus appears to record the migrations, expansions and contractions of the Martian polar cap.

Theory of electromagnetic insertion devices and the corresponding synchrotron radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shumail, Muhammad; Tantawi, Sami G.

Permanent magnet insertion devices (IDs), which are the main radiation generating devices in synchrotron light sources and free-electron lasers, use a time-invariant but space-periodic magnetic field to wiggle relativistic electrons for short-wavelength radiation generation. Recently, a high power microwave based undulator has also been successfully demonstrated at SLAC which promises the advantage of dynamic tunability of radiation spectrum and polarization. Such IDs employ transverse elecromagnetic fields which are periodic in both space and time to undulate the electrons. In this paper we develop a detailed theory of the principle of electromagnetic IDs from first principles for both linear and circularmore » polarization modes. The electromagnetic equivalent definitions of undulator period (λ u) and undulator deflection parameter (K) are derived. In the inertial frame where the average momentum of the electron is zero, we obtain the figure-8-like trajectory for the linear polarization mode and the circular trajectory for the circular polarization mode. As a result, the corresponding radiation spectra and the intensity of harmonics is also calculated.« less

Theory of electromagnetic insertion devices and the corresponding synchrotron radiation

DOE PAGES

Shumail, Muhammad; Tantawi, Sami G.

2016-07-27

Permanent magnet insertion devices (IDs), which are the main radiation generating devices in synchrotron light sources and free-electron lasers, use a time-invariant but space-periodic magnetic field to wiggle relativistic electrons for short-wavelength radiation generation. Recently, a high power microwave based undulator has also been successfully demonstrated at SLAC which promises the advantage of dynamic tunability of radiation spectrum and polarization. Such IDs employ transverse elecromagnetic fields which are periodic in both space and time to undulate the electrons. In this paper we develop a detailed theory of the principle of electromagnetic IDs from first principles for both linear and circularmore » polarization modes. The electromagnetic equivalent definitions of undulator period (λ u) and undulator deflection parameter (K) are derived. In the inertial frame where the average momentum of the electron is zero, we obtain the figure-8-like trajectory for the linear polarization mode and the circular trajectory for the circular polarization mode. As a result, the corresponding radiation spectra and the intensity of harmonics is also calculated.« less

Widely tunable narrow-band coherent Terahertz radiation from an undulator at THU

NASA Astrophysics Data System (ADS)

Su, X.; Wang, D.; Tian, Q.; Liang, Y.; Niu, L.; Yan, L.; Du, Y.; Huang, W.; Tang, C.

2018-01-01

There is anxious demand for intense widely tunable narrow-band Terahertz (THz) radiation in scientific research, which is regarded as a powerful tool for the coherent control of matter. We report the generation of widely tunable THz radiation from a planar permanent magnet undulator at Tsinghua University (THU). A relativistic electron beam is compressed by a magnetic chicane into sub-ps bunch length to excite THz radiation in the undulator coherently. The THz frequency can be tuned from 0.4 THz to 10 THz continuously with narrow-band spectrums when the undulator gap ranges from 23 mm to 75 mm. The measured pulse THz radiation energy from 220 pC bunch is 3.5 μJ at 1 THz and tens of μJ pulse energy (corresponding peak power of 10 MW) can be obtained when excited by 1 nC beam extrapolated from the property of coherent radiation. The experimental results agree well with theoretical predictions, which demonstrates a suitable THz source for the many applications that require intense and widely tunable THz sources.

Diffraction effects in mechanically chopped laser pulses

NASA Astrophysics Data System (ADS)

Gambhir, Samridhi; Singh, Mandip

2018-06-01

A mechanical beam chopper consists of a rotating disc of regularly spaced wide slits which allow light to pass through them. A continuous light beam, after passing through the rotating disc, is switched-on and switched-off periodically, and a series of optical pulses are produced. The intensity of each pulse is expected to rise and fall smoothly with time. However, a careful study has revealed that the edges of mechanically chopped laser light pulses consist of periodic intensity undulations which can be detected with a photo detector. In this paper, it is shown that the intensity undulations in mechanically chopped laser pulses are produced by diffraction of light from the rotating disc, and a detailed explanation is given of the intensity undulations in mechanically chopped laser pulses. An experiment presented in this paper provides an efficient method to capture a one dimensional diffraction profile of light from a straight sharp-edge in the time domain. In addition, the experiment accurately measures wavelengths of three different laser beams from the undulations in mechanically chopped laser light pulses.

A simple optical system delivering a tunable micrometer pink beam that can compensate for heat-induced deformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reininger, Ruben; Liu, Zunping; Doumy, Gilles

2015-06-09

The radiation from an undulator reflected from one or more optical elements (usually termed `pink-beam') is used in photon-hungry experiments. The optical elements serve as a high-energy cutoff and for focusing purposes. One of the issues with this configuration is maintaining the focal spot dimension as the energy of the undulator is varied, since this changes the heat load absorbed by the first optical element. Finite-element analyses of the power absorbed by a side water-cooled mirror exposed to the radiation emitted by an undulator at the Advanced Photon Source (APS) and at the APS after the proposed upgrade (APSU) revealsmore » that the mirror deformation is very close to a convex cylinder creating a virtual source closer to the mirror than the undulator source. Here a simple optical system is described based on a Kirkpatrick–Baez pair which keeps the focus size to less than 2 µm (in the APSU case) with a working distance of 350 mm despite the heat-load-induced change in source distance. Detailed ray tracings at several photon energies for both the APS and APSU show that slightly decreasing the angle of incidence on the mirrors corrects the change in the `virtual' position of the source. The system delivers more than 70% of the first undulator harmonic with very low higher-orders contamination for energies between 5 and 10 keV.« less

Accuracy assessment of linear spectral mixture model due to terrain undulation

NASA Astrophysics Data System (ADS)

Wang, Tianxing; Chen, Songlin; Ma, Ya

2008-12-01

Mixture spectra are common in remote sensing due to the limitations of spatial resolution and the heterogeneity of land surface. During the past 30 years, a lot of subpixel model have developed to investigate the information within mixture pixels. Linear spectral mixture model (LSMM) is a simper and more general subpixel model. LSMM also known as spectral mixture analysis is a widely used procedure to determine the proportion of endmembers (constituent materials) within a pixel based on the endmembers' spectral characteristics. The unmixing accuracy of LSMM is restricted by variety of factors, but now the research about LSMM is mostly focused on appraisement of nonlinear effect relating to itself and techniques used to select endmembers, unfortunately, the environment conditions of study area which could sway the unmixing-accuracy, such as atmospheric scatting and terrain undulation, are not studied. This paper probes emphatically into the accuracy uncertainty of LSMM resulting from the terrain undulation. ASTER dataset was chosen and the C terrain correction algorithm was applied to it. Based on this, fractional abundances for different cover types were extracted from both pre- and post-C terrain illumination corrected ASTER using LSMM. Simultaneously, the regression analyses and the IKONOS image were introduced to assess the unmixing accuracy. Results showed that terrain undulation could dramatically constrain the application of LSMM in mountain area. Specifically, for vegetation abundances, a improved unmixing accuracy of 17.6% (regression against to NDVI) and 18.6% (regression against to MVI) for R2 was achieved respectively by removing terrain undulation. Anyway, this study indicated in a quantitative way that effective removal or minimization of terrain illumination effects was essential for applying LSMM. This paper could also provide a new instance for LSMM applications in mountainous areas. In addition, the methods employed in this study could be effectively used to evaluate different algorithms of terrain undulation correction for further study.

Micropole undulator

DOEpatents

Tatchyn, R.O.; Csonka, P.L.; Cremer, J.T.

1990-12-11

Micropole undulators for use in the generation of x-rays from moving charged particles are disclosed. Two rows of spaced apart poles are arranged so that each pole produces a magnetic field aligned with all other similar fields. The poles are the ends of C''-shaped magnets. In each row, adjacent poles are separated by spacers made of a superconducting material. 11 figs.

APS undulator and wiggler sources: Monte-Carlo simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, S.L.; Lai, B.; Viccaro, P.J.

1992-02-01

Standard insertion devices will be provided to each sector by the Advanced Photon Source. It is important to define the radiation characteristics of these general purpose devices. In this document,results of Monte-Carlo simulation are presented. These results, based on the SHADOW program, include the APS Undulator A (UA), Wiggler A (WA), and Wiggler B (WB).

Advantage and Challenges of $$Nb_3Sn$$ Superconducting Undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zlobin, A. V.; Barzi, E.; Turrinoni, D.

Utilization of Nb3Sn superconducting wires offers the possibility to increase undulators’ nominal operation field and temperature margin, but requires overcoming chal-lenges that are described in this paper. The achievable field levels for a Nb3Sn version of superconducting undulators being developed at APS-ANL and the conductor choice are also presented and discussed.

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources.

PubMed

Tang, M X; Zhang, Y Y; E, J C; Luo, S N

2018-05-01

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic-plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of the diffraction patterns is discussed.

New beamline optics of the x-ray undulator BW1 at DORIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahn, U.; Frahm, R.; Guertler, P.

1996-12-31

The X-ray undulator BW1 at the storage ring DORIS is a high brightness source for the spectral range from 2 to 20 keV. The undulator beam is used by three experiments with different distances to the source. The new optical elements allow the adaptation of the focal lengths to the needs of the experimental set-ups. The optical concept consists of a premirror with different optical surfaces, a double crystal monochromator and a focusing second mirror. Sagittal focusing is achieved either by using the cylindrical part of the premirror or by a bend crystal for a monochromatic beam, meridional focusing ismore » done with a pneumatic driven mirror bender for the second mirror.« less

Generalized Models for Rock Joint Surface Shapes

PubMed Central

Du, Shigui; Hu, Yunjin; Hu, Xiaofei

2014-01-01

Generalized models of joint surface shapes are the foundation for mechanism studies on the mechanical effects of rock joint surface shapes. Based on extensive field investigations of rock joint surface shapes, generalized models for three level shapes named macroscopic outline, surface undulating shape, and microcosmic roughness were established through statistical analyses of 20,078 rock joint surface profiles. The relative amplitude of profile curves was used as a borderline for the division of different level shapes. The study results show that the macroscopic outline has three basic features such as planar, arc-shaped, and stepped; the surface undulating shape has three basic features such as planar, undulating, and stepped; and the microcosmic roughness has two basic features such as smooth and rough. PMID:25152901

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, M. X.; Zhang, Y. Y.; E, J. C.

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic–plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of themore » diffraction patterns is discussed.« less

Absolute measurement of undulator radiation in the extreme ultraviolet

NASA Astrophysics Data System (ADS)

Maezawa, H.; Mitani, S.; Suzuki, Y.; Kanamori, H.; Tamamushi, S.; Mikuni, A.; Kitamura, H.; Sasaki, T.

1983-04-01

The spectral brightness of undulator radiation emitted by the model PMU-1 incorporated in the SOR-RING, the dedicated synchrotron radiation source in Tokyo, has been studied in the extreme ultraviolet region from 21.6 to 72.9 eV as a function of the electron energy γ, the field parameter K, and the angle of observation ϴ in the absolute scale. A series of measurements covering the first and the second harmonic component of undulator radiation was compared with the fundamental formula λ n= {λ 0}/{2nγ 2}( {1+K 2}/{2}+γϴ 2 and the effects of finite emittance were studied. The brightness at the first peak was smaller than the theoretical value, while an enhanced second harmonic component was observed.

Fish optimize sensing and respiration during undulatory swimming.

PubMed

Akanyeti, O; Thornycroft, P J M; Lauder, G V; Yanagitsuru, Y R; Peterson, A N; Liao, J C

2016-03-24

Previous work in fishes considers undulation as a means of propulsion without addressing how it may affect other functions such as sensing and respiration. Here we show that undulation can optimize propulsion, flow sensing and respiration concurrently without any apparent tradeoffs when head movements are coupled correctly with the movements of the body. This finding challenges a long-held assumption that head movements are simply an unintended consequence of undulation, existing only because of the recoil of an oscillating tail. We use a combination of theoretical, biological and physical experiments to reveal the hydrodynamic mechanisms underlying this concerted optimization. Based on our results we develop a parsimonious control architecture that can be used by both undulatory animals and machines in dynamic environments.

Fish optimize sensing and respiration during undulatory swimming

PubMed Central

Akanyeti, O.; Thornycroft, P. J. M.; Lauder, G. V.; Yanagitsuru, Y. R.; Peterson, A. N.; Liao, J. C.

2016-01-01

Previous work in fishes considers undulation as a means of propulsion without addressing how it may affect other functions such as sensing and respiration. Here we show that undulation can optimize propulsion, flow sensing and respiration concurrently without any apparent tradeoffs when head movements are coupled correctly with the movements of the body. This finding challenges a long-held assumption that head movements are simply an unintended consequence of undulation, existing only because of the recoil of an oscillating tail. We use a combination of theoretical, biological and physical experiments to reveal the hydrodynamic mechanisms underlying this concerted optimization. Based on our results we develop a parsimonious control architecture that can be used by both undulatory animals and machines in dynamic environments. PMID:27009352

Optimized design and structural mechanics of a single-piece composite helicopter driveshaft

NASA Astrophysics Data System (ADS)

Henry, Todd C.

In rotorcraft driveline design, single-piece composite driveshafts have much potential for reducing driveline mass and complexity over multi-segmented metallic driveshafts. The singlepiece shaft concept is enabled by the relatively high fatigue strain capacity of fiber reinforced polymer composites over metals. Challenges for single-piece driveshaft design lie in addressing the self-heating behavior of the composite due to the material damping, as well as, whirling stability, torsional buckling stability, and composite strength. Increased composite temperature due to self-heating reduces the composite strength and is accounted for in this research. The laminate longitudinal stiffness ( Ex) and strength (Fx) are known to be heavily degraded by fiber undulation, however, both are not well understood in compression. The whirling stability (a function of longitudinal stiffness) and the composite strength are strongly influential in driveshaft optimization, and thus are investigated further through the testing of flat and filament wound composite specimens. The design of single-piece composite driveshafts, however, needs to consider many failure criteria, including hysteresis-induced overheating, whirl stability, torsional buckling stability, and material failure by overstress. The present investigation uses multi-objective optimization to investigate the design space which visually highlights design trades. Design variables included stacking sequence, number of laminas, and number of hanger bearings. The design goals were to minimize weight and maximize the lowest factor of safety by adaptively generating solutions to the multi-objective problem. Several design spaces were investigated by examining the effect of misalignment, ambient temperature, and constant power transmission on the optimized solution. Several materials of interest were modeled using experimentally determined elastic properties and novel temperature-dependent composite strength. Compared to the baseline multi-segmented metallic driveline, weight reductions of 43% and 48% were obtained for single-piece flexible and rigid matrix composite shafts. The rigid matrix weight reduction was slightly lower than that seen in the literature due to consideration of shaft misalignment. In filament wound composites, the existence of fiber undulation introduces unique challenges in the prediction of compressive modulus and strength using traditional laminated composite theories. In the current investigation, novel full field strain measurements of compressively loaded specimens were used to evaluate local strain distributions in the region of a 0-deg. undulated lamina in a [0n/90n] s laminate (n=2,4,6) and a 30-deg. undulated lamina in a [30n/-60n] s laminate (n=2,4). Unique to this research, specimens were fabricated with carbon fibers, various amplitudes of undulation, and matrix materials with three different moduli of elasticity. Full-field strains were measured on the free edge and across the width of the compressively loaded specimens using two-dimensional digital image correlation (DIC). The observed strains were highly influenced by the undulation geometry. The longitudinal modulus of a [0n/90n] s laminate was more sensitive to reinforcement undulation when the matrix was flexible rather than rigid. An undulation with an amplitude/length ratio of 0.1 (low for a filament wound cylinder) reduces the average longitudinal modulus of elasticity in the undulation region by approximately 43% and 3% in laminates with flexible and rigid matrices, respectively, relative to a similar material without undulation. Observations of strain on the free edge revealed that fiber undulation caused elevated out-of-plane shear (gamma xz) and through-thickness normal (epsilonzz) strains in regions eventually involved in the fiber microbuckling failure process. A new three dimensional method was derived for the homogenization of a heterogeneous composite laminate consisting of individual anisotropic lamina for which structural coupling (Bij) may occur due to in- and out-of-plane (undulation) fiber reinforcement orientation. Threedimensional elastic constants were calculated by considering a representative volume element taken from the heterogeneous laminate. Three-dimensional elastic constant predictions were validated through comparison with established methods, both two- and three- dimensional. When the new derived three dimensional theory was applied to experimental results, the modulus and strength predictions compared favorably. A series of [+/-theta/89/+/-theta] cylinders with multiple helical fiber angles, winding patterns, and matrix materials were fabricated and tested in compression. Digital image correlation was used for the first time to measure outside surface displacements and strains. Longitudinal and hoop direction strain fluctuations between the undulated and non-undulated regions were found to be of the order of 20-30% of the mean values throughout the cylinders. Qualitatively, these fluctuations can be related to non-classical elastic couplings (Bij) in the anti-symmetric regions of the filament winding pattern. Failure of the cylinder occurred by fiber microbuckling, which initiated near the crossing of circumferential and helical cross-over bands. Based on a statistical analysis of surface strains in the local fiber coordinate system, it was determined that longitudinal compressive and in-plane longitudinal shear strains at incipient microbuckling were two to four times greater than their respective global counterparts. These results indicate the magnitude of strain concentration existing in the cylinders immediately before final failure (possibly during local failure) and highlight the importance of longitudinal compressive (epsilon11) and in-plane longitudinal shear strains (gamma12) in the failure process. A novel local-global approach was used in predicting the longitudinal modulus and strength of filament wound cylinders. Several representative volume elements were chosen to represent the filament winding rhombus, and were used as a basis for homogenization. Strength predictions were augmented with empirical critical distance factors. The average Ex and nu xy prediction error for Conathane DPRN 30917 was 6.8 % and 21 % and the average error for EPON 862 was 9.7 % and 14 % respectively. The strength prediction error was approximately 7.7 % and 24 % for 30917 and EPON 862 with failure location typically at the circumferential undulation by mode sigma 6 (tau12). The failure mode prediction was consistent with experimental observations from filament wound cylinders and flat-undulated specimens of similar lamination arrangement. Additional comparison with previous Adiprene LF750 filament wound cylinder testing produced prediction error of 11.8 % and 8.9 % for longitudinal modulus and strength respectively. The average absolute value of the error, considering every material, for modulus, strength, and Poisson's ratio was 14 %. Application of critical distance factors to flat undulated specimens was deemed unadvisable due to considerably higher strain intensity at failure compared to filament wound cylinders.

Construction of CHESS compact undulator magnets at Kyma

NASA Astrophysics Data System (ADS)

Temnykh, Alexander B.; Lyndaker, Aaron; Kokole, Mirko; Milharcic, Tadej; Pockar, Jure; Geometrante, Raffaella

2015-05-01

In 2014 KYMA S.r.l. has built two CHESS Compact Undulator (CCU) magnets that are at present installed and successfully operate at the Cornell Electron Storage Ring. This type of undulator was developed for upgrade of Cornell High Energy Synchrotron Source beam-lines, but it can be used elsewhere as well. CCU magnets are compact, lightweight, cost efficient and in-vacuum compatible. They are linearly polarized undulators and have a fixed gap. Magnetic field tuning is achieved by phasing (shifting) top magnetic array relative bottom. Two CCUs constructed by KYMA S.r.l. have 28.4 mm period, 6.5 mm gap, 0.93 T peak field. Magnetic structure is of PPM type, made with NdFeB (40UH grade) permanent magnet material. Transitioning from the laboratory to industrial environment for a novel design required additional evaluation, design adjusting and extensive testing. Particular attention was given to the soldering technique used for fastening of the magnetic blocks to holders. This technique had thus far never been used before for undulator magnet construction by industry. The evaluation included tests of different types of soldering paste, measurements of strength of solder and determining the deformations of the soldered magnet and holder under simulated loading forces. This paper focuses on critical features of the CCU design, results of the soldering technique testing and the data regarding permanent magnets magnetization change due to soldering. In addition it deals with optimization-assisted assembly and the performance of the assembled devices and assesses some of the results of the CCU magnets operation at CESR.

Structure and function of the undulating membrane in spermatozoan propulsion in the toad Bufo marinus

PubMed Central

1980-01-01

Accessory fibers in most sperm surround the axoneme so that their function in propulsion is difficult to assess. In the sperm of the toad Bufo marinus, an accessory fiber is displaced from the axoneme, being connected to it by the thin undulating membrane in such a way that the movement of axoneme and accessory fiber can be viewed independently. The axoneme is highly convoluted in whole mounts, and the axial fiber is straight. Cinemicrographic analysis shows that it is the longer, flexuous fiber, the presumed axoneme, that move actively. The accessory fiber follows it passively with a lower amplitude of movement. The accessory fiber does not move independent of the axoneme, even after demembranation and reactivation of the sperm. On the basis of anatomical relations in the neck region, it appears that the accessory fibers of amphibians are analogous to the dense fibers of mammalian sperm. SDS polyacrylamide gel electrophoresis of demembranated toad sperm tails reveals two principal proteins in addition to the tubulins, the former probably arising from the accessory fibers and the matrix of the undulating membrane. The function of displacing an accessory fiber into an undulating membrane may be to provide stiffness for the tail without incurring an energy deficit large enough to require a long middle piece. A long middle piece is not present in toad sperm, in contrast to those sperm that have accessory fibers around the axoneme. However, the toad sperm suffers a reduction in speed of about one- third, compared with the speed expected for a sperm without an undulating membrane. PMID:6771299

Geoid undulation accuracy

NASA Technical Reports Server (NTRS)

Rapp, Richard H.

1993-01-01

The determination of the geoid and equipotential surface of the Earth's gravity field, has long been of interest to geodesists and oceanographers. The geoid provides a surface to which the actual ocean surface can be compared with the differences implying information on the circulation patterns of the oceans. For use in oceanographic applications the geoid is ideally needed to a high accuracy and to a high resolution. There are applications that require geoid undulation information to an accuracy of +/- 10 cm with a resolution of 50 km. We are far from this goal today but substantial improvement in geoid determination has been made. In 1979 the cumulative geoid undulation error to spherical harmonic degree 20 was +/- 1.4 m for the GEM10 potential coefficient model. Today the corresponding value has been reduced to +/- 25 cm for GEM-T3 or +/- 11 cm for the OSU91A model. Similar improvements are noted by harmonic degree (wave-length) and in resolution. Potential coefficient models now exist to degree 360 based on a combination of data types. This paper discusses the accuracy changes that have taken place in the past 12 years in the determination of geoid undulations.

Methods for the computation of detailed geoids and their accuracy

NASA Technical Reports Server (NTRS)

Rapp, R. H.; Rummel, R.

1975-01-01

Two methods for the computation of geoid undulations using potential coefficients and 1 deg x 1 deg terrestrial anomaly data are examined. It was found that both methods give the same final result but that one method allows a more simplified error analysis. Specific equations were considered for the effect of the mass of the atmosphere and a cap dependent zero-order undulation term was derived. Although a correction to a gravity anomaly for the effect of the atmosphere is only about -0.87 mgal, this correction causes a fairly large undulation correction that was not considered previously. The accuracy of a geoid undulation computed by these techniques was estimated considering anomaly data errors, potential coefficient errors, and truncation (only a finite set of potential coefficients being used) errors. It was found that an optimum cap size of 20 deg should be used. The geoid and its accuracy were computed in the Geos 3 calibration area using the GEM 6 potential coefficients and 1 deg x 1 deg terrestrial anomaly data. The accuracy of the computed geoid is on the order of plus or minus 2 m with respect to an unknown set of best earth parameter constants.

Expected Performance of the LHC Synchrotron-Light Telescope (BSRT) and Abort-Gap Monitor (BSRA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fisher, Alan; /SLAC

2010-06-07

This Report presents calculations of the synchrotron light from proton and lead-ion beams in the LHC at all energies from 0.45 to 7 TeV. It computes the emission from three sources: the uniform-field region of the D3 dipole, the dipole's edge field, and the short undulator just upstream. Light emitted at or near visible wavelengths is assessed for making optical measurements of transverse beam profiles and for monitoring the emptiness of the abort gap in the fill pattern. There is sufficient light for both applications, although both species pass through energy ranges in the ramp with small photon counts. Effectsmore » limiting image resolution are examined, including geometric optics, depth of field, and diffraction. The Report also considers recent suggestions that the undulator, intended to supplement the dipole for low energies, should not be ramped off at high energies and perhaps should not be used at all. We conclude that the undulator is essential at low energy for both species, but that it is possible to leave the undulator on at the cost of some blurring at intermediate energies.« less

Isolated few-cycle radiation from chirped-pulse compression of a superradiant free-electron laser

DOE PAGES

Huang, Yen -Chieh; Zhang, Zhen; Chen, Chia -Hsiang; ...

2015-08-31

When a short electron bunch traverses an undulator to radiate a wavelength longer than the bunch length, intense superradiance from the electron bunch can quickly deplete the electron’s kinetic energy and lead to generation of an isolated chirped radiation pulse. Here, we develop a theory to describe this novel chirped pulse radiation in a superradiant free-electron laser and show the opportunity to generate isolated few-cycle high-power radiation through chirped-pulse compression after the undulator. The theory is completely characterized by how fast the electron energy is depleted for a given length of an undulator. We further present two design examples atmore » the THz and extreme-ultraviolet wavelengths and numerically generate isolated three- and nine-cycle radiation pulses, respectively.« less

Thermal Modeling and Cryogenic Design of a Helical Superconducting Undulator Cryostat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiroyanagi, Y.; Fuerst, J.; Hasse, Q.

A conceptual design for a helical superconducting undulator (HSCU) for the Advanced Photon Source (APS) at Argonne National Laboratory (ANL) has been completed. The device differs sufficiently from the existing APS planar superconducting undulator (SCU) design to warrant development of a new cryostat based on value engineering and lessons learned from the existing planar SCU. Changes include optimization of the existing cryocooler-based refrigeration system and thermal shield as well as cost reduction through the use of standard vacuum hardware. The end result is a design that provides significantly larger 4.2 K refrigeration margin in a smaller package for greater installationmore » flexibility in the APS storage ring. This paper presents ANSYS-based thermal analysis of the cryostat, including estimated static and dynamic« less

Insertion device calculations with mathematica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, R.; Lidia, S.

1995-02-01

The design of accelerator insertion devices such as wigglers and undulators has usually been aided by numerical modeling on digital computers, using code in high level languages like Fortran. In the present era, there are higher level programming environments like IDL{reg_sign}, MatLab{reg_sign}, and Mathematica{reg_sign} in which these calculations may be performed by writing much less code, and in which standard mathematical techniques are very easily used. The authors present a suite of standard insertion device modeling routines in Mathematica to illustrate the new techniques. These routines include a simple way to generate magnetic fields using blocks of CSEM materials, trajectorymore » solutions from the Lorentz force equations for given magnetic fields, Bessel function calculations of radiation for wigglers and undulators and general radiation calculations for undulators.« less

Terahertz radiation source using a high-power industrial electron linear accelerator

NASA Astrophysics Data System (ADS)

Kalkal, Yashvir; Kumar, Vinit

2017-04-01

High-power (˜ 100 kW) industrial electron linear accelerators (linacs) are used for irradiations, e.g., for pasteurization of food products, disinfection of medical waste, etc. We propose that high-power electron beam from such an industrial linac can first pass through an undulator to generate useful terahertz (THz) radiation, and the spent electron beam coming out of the undulator can still be used for the intended industrial applications. This will enhance the utilization of a high-power industrial linac. We have performed calculation of spontaneous emission in the undulator to show that for typical parameters, continuous terahertz radiation having power of the order of μW can be produced, which may be useful for many scientific applications such as multispectral imaging of biological samples, chemical samples etc.

Vertically polarizing undulator with dynamic compensation of magnetic forces

DOE PAGES

Strelnikov, N.; Vasserman, I.; Xu, J.; ...

2017-01-20

As part of the R&D program of the LCLS-II project, a novel 3.4-meter-long undulator prototype with horizontal magnetic field and dynamic force compensation has recently been developed at the Advanced Photon Source (APS). Some previous steps in this development were the shorter 0.8-meter-long and 2.8-meter-long prototypes. Extensive mechanical and magnetic testing was carried out for each prototype, and each prototype was magnetically tuned using magnetic shims. Furthermore, the resulting performance of the 3.4-meter-long undulator prototype meets all requirements for the LCLS-II insertion device, including limits on the field integrals, phase errors, higher-order magnetic moments, and electron-beam trajectory for all operationalmore » gaps, as well as the reproducibility and accuracy of the gap settings.« less

Construction and Commissioning of A 248 m-long Beamline with X-ray Undulator Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Yoshio; Uesugi, Kentaro; Takimoto, Naoki

2004-05-12

A medium-length beamline with undulator source, BL20XU at SPring-8, was constructed, and opened to public use. The distance from source point to the end of the beamline is 248 m. By utilizing the long beam transport path, the beamline has advantages for experiment that requires high spatial coherence in hard X-ray regions.

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line

NASA Astrophysics Data System (ADS)

Arnold, N. D.; Attig, J.; Banks, G.; Bechtold, R.; Beczek, K.; Benson, C.; Berg, S.; Berg, W.; Biedron, S. G.; Biggs, J. A.; Borland, M.; Boerste, K.; Bosek, M.; Brzowski, W. R.; Budz, J.; Carwardine, J. A.; Castro, P.; Chae, Y.-C.; Christensen, S.; Clark, C.; Conde, M.; Crosbie, E. A.; Decker, G. A.; Dejus, R. J.; DeLeon, H.; Den Hartog, P. K.; Deriy, B. N.; Dohan, D.; Dombrowski, P.; Donkers, D.; Doose, C. L.; Dortwegt, R. J.; Edwards, G. A.; Eidelman, Y.; Erdmann, M. J.; Error, J.; Ferry, R.; Flood, R.; Forrestal, J.; Freund, H.; Friedsam, H.; Gagliano, J.; Gai, W.; Galayda, J. N.; Gerig, R.; Gilmore, R. L.; Gluskin, E.; Goeppner, G. A.; Goetzen, J.; Gold, C.; Gorski, A. J.; Grelick, A. E.; Hahne, M. W.; Hanuska, S.; Harkay, K. C.; Harris, G.; Hillman, A. L.; Hogrefe, R.; Hoyt, J.; Huang, Z.; Jagger, J. M.; Jansma, W. G.; Jaski, M.; Jones, S. J.; Keane, R. T.; Kelly, A. L.; Keyser, C.; Kim, K.-J.; Kim, S. H.; Kirshenbaum, M.; Klick, J. H.; Knoerzer, K.; Koldenhoven, R. J.; Knott, M.; Labuda, S.; Laird, R.; Lang, J.; Lenkszus, F.; Lessner, E. S.; Lewellen, J. W.; Li, Y.; Lill, R. M.; Lumpkin, A. H.; Makarov, O. A.; Markovich, G. M.; McDowell, M.; McDowell, W. P.; McNamara, P. E.; Meier, T.; Meyer, D.; Michalek, W.; Milton, S. V.; Moe, H.; Moog, E. R.; Morrison, L.; Nassiri, A.; Noonan, J. R.; Otto, R.; Pace, J.; Pasky, S. J.; Penicka, J. M.; Pietryla, A. F.; Pile, G.; Pitts, C.; Power, J.; Powers, T.; Putnam, C. C.; Puttkammer, A. J.; Reigle, D.; Reigle, L.; Ronzhin, D.; Rotela, E. R.; Russell, E. F.; Sajaev, V.; Sarkar, S.; Scapino, J. C.; Schroeder, K.; Seglem, R. A.; Sereno, N. S.; Sharma, S. K.; Sidarous, J. F.; Singh, O.; Smith, T. L.; Soliday, R.; Sprau, G. A.; Stein, S. J.; Stejskal, B.; Svirtun, V.; Teng, L. C.; Theres, E.; Thompson, K.; Tieman, B. J.; Torres, J. A.; Trakhtenberg, E. M.; Travish, G.; Trento, G. F.; Vacca, J.; Vasserman, I. B.; Vinokurov, N. A.; Walters, D. R.; Wang, J.; Wang, X. J.; Warren, J.; Wesling, S.; Weyer, D. L.; Wiemerslage, G.; Wilhelmi, K.; Wright, R.; Wyncott, D.; Xu, S.; Yang, B.-X.; Yoder, W.; Zabel, R. B.

2001-12-01

Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

Arm to leg coordination in elite butterfly swimmers.

PubMed

Chollet, D; Seifert, L; Boulesteix, L; Carter, M

2006-04-01

This study proposed the use of four time gaps to assess arm-to-leg coordination in the butterfly stroke at increasing race paces. Fourteen elite male swimmers swam at four velocities corresponding to the appropriate paces for, respectively, the 400-m, 200-m, 100-m, and 50-m events. The different stroke phases of the arm and leg were identified by video analysis and then used to calculate four time gaps (T1: time gap between entry of the hands in the water and the high break-even point of the first undulation; T2: time gap between the beginning of the hands' backward movement and the low break-even point of the first undulation; T3: time gap between the hands' arrival in a vertical plane to the shoulders and the high break-even point of the second undulation; T4: time gap between the hands' release from the water and the low break-even point of the second undulation), the values of which described the changing relationship of arm to leg movements over an entire stroke cycle. With increases in pace, elite swimmers increased the stroke rate, the relative duration of the arm pull, the recovery and the first downward movement of the legs, and decreased the stroke length, the relative duration of the arm catch phase and the body glide with arms forward (measured by T2), until continuity in the propulsive actions was achieved. Whatever the paces, the T1, T3, and T4 values were close to zero and revealed a high degree of synchronisation at key motor points of the arm and leg actions. This new method to assess butterfly coordination could facilitate learning and coaching by situating the place of the leg undulation in relation with the arm stroke.

Compensating the electron beam energy spread by the natural transverse gradient of laser undulator in all-optical x-ray light sources.

PubMed

Zhang, Tong; Feng, Chao; Deng, Haixiao; Wang, Dong; Dai, Zhimin; Zhao, Zhentang

2014-06-02

All-optical ideas provide a potential to dramatically cut off the size and cost of x-ray light sources to the university-laboratory scale, with the combination of the laser-plasma accelerator and the laser undulator. However, the large longitudinal energy spread of the electron beam from laser-plasma accelerator may hinder the way to high brightness of these all-optical light sources. In this paper, the beam energy spread effect is proposed to be significantly compensated by the natural transverse gradient of a laser undulator when properly transverse-dispersing the electron beam. Theoretical analysis and numerical simulations on conventional laser-Compton scattering sources and high-gain all-optical x-ray free-electron lasers with the electron beams from laser-plasma accelerators are presented.

Analysis of a static undulation on the surface of a thin dielectric liquid layer formed by dielectrophoresis forces

NASA Astrophysics Data System (ADS)

Brown, Carl V.; McHale, Glen; Mottram, Nigel J.

2011-07-01

A layer of insulating liquid of dielectric constant ɛOil and average thickness h- coats a flat surface at y = 0 at which a one-dimensional sinusoidal potential V(x ,0)=VOcos(πx /p) is applied. Dielectrophoresis forces create a static undulation (or "wrinkle") distortion h(x) of period p at the liquid/air interface. Analytical expressions have been derived for the electrostatic energy and the interfacial energy associated with the surface undulation when h(x)=h--(1/2)Acos(2πx /p) yielding a scaling relationship for A as a function of h-, p, VO, ɛOil and the surface tension. The analysis is valid as A/p → 0, and in this limit convergence with numerical simulation of the system is shown.

FEL (free-electron lasers) undulator technology and synchrotron radiation source requirements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, K.; Quimby, D.; Slater, J.

This paper describes design and construction considerations of the THUNDER undulator, for use in free-electron laser experiments at visible wavelengths. For the parameters of these experiments, an unusually high degree of optimization of the electron-photon interaction is required and, as a result, THUNDER is built to especially high mechanical and magnetic precision. Except for its narrow magnet gap, the 5-meter THUNDER undulator is quite similar to insertion devices under consideration for the proposed 6-GeV storage ring. The engineering and physics approach adopted for this FEL modulator design is directly applicable to insertion device development. The tolerance limits to THUNDER, establishedmore » by modeling and design and achieved through careful control of mechanical and magnetic errors, are essential to the next generation of insertion devices.« less

Initial performances of first undulator-based hard x-ray beamlines of NSLS-II compared to simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chubar, Oleg, E-mail: chubar@bnl.gov; Chu, Yong S.; Huang, Xiaojing

2016-07-27

Commissioning of the first X-ray beamlines of NSLS-II included detailed measurements of spectral and spatial distributions of the radiation at different locations of the beamlines, from front-ends to sample positions. Comparison of some of these measurement results with high-accuracy calculations of synchrotron (undulator) emission and wavefront propagation through X-ray transport optics, performed using SRW code, is presented.

Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dooling, J.; Harkay, K.; Ivanyushenkov, Y.

2015-01-01

We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 (“ID6”) since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 (“ID1”) in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenchingwhen the SCU0windings are nearmore » critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in ID6 on the SCU0 chamber transitions and in ID1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.« less

Cryogenic Permanent Magnet Undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chavanne, J.; Lebec, G.; Penel, C.

For an in-vacuum undulator operated at small gaps the permanent magnet material needs to be highly resistant to possible electron beam exposure. At room temperature, one generally uses Sm{sub 2}Co{sub 17} or high coercivity NdFeB magnets at the expense of a limited field performance. In a cryogenic permanent magnet undulator (CPMU), at a temperature of around 150 K, any NdFeB grade reveals a coercivity large enough to be radiation resistant. In particular, very high remanence NdFeB material can be used to build undulators with enhanced field and X-ray brilliance at high photon energy provided that the pre-baking of the undulatormore » above 100 deg. C can be eliminated. The ESRF has developed a full scale 2 m long CPMU with a period of 18 mm. This prototype has been in operation on the ID6 test beamline since January 2008. A significant effort was put into the characterization of NdFeB material at low temperature, the development of dedicated magnetic measurement systems and cooling methods. The measured heat budget with beam is found to be larger than expected without compromising the smooth operation of the device. Leading on from this first experience, new CPMUs are currently being considered for the upgrade of the ESRF.« less

Swimming at low Reynolds number: a beginners guide to undulatory locomotion

NASA Astrophysics Data System (ADS)

Cohen, Netta; Boyle, Jordan H.

2010-03-01

Undulatory locomotion is a means of self-propulsion that relies on the generation and propagation of waves along a body. As a mode of locomotion it is primitive and relatively simple, yet can be remarkably robust. No wonder then, that it is so prevalent across a range of biological scales from motile bacteria to gigantic prehistoric snakes. Key to understanding undulatory locomotion is the body's interplay with the physical environment, which the swimmer or crawler will exploit to generate propulsion, and in some cases, even to generate the underlying undulations. This review focuses by and large on undulators in the low Reynolds number regime, where the physics of the environment can be much more tractable. We review some key concepts and theoretical advances, as well as simulation tools and results applied to selected examples of biological swimmers. In particular, we extend the discussion to some simple cases of locomotion in non-Newtonian media as well as to small animals, in which the nervous system, motor control, body properties and the environment must all be considered to understand how undulations are generated and modulated. To conclude, we review recent progress in microrobotic undulators that may one day become commonplace in applications ranging from toxic waste disposal to minimally invasive surgery.

Effect of hand paddles and parachute on butterfly coordination.

PubMed

Telles, Thiago; Barroso, Renato; Barbosa, Augusto Carvalho; Salgueiro, Diego Fortes de Souza; Colantonio, Emilson; Andries Júnior, Orival

2015-01-01

This study investigated the effects of hand paddles, parachute and hand paddles plus parachute on the inter-limb coordination of butterfly swimming. Thirteen male swimmers were evaluated in four random maximal intensity conditions: without equipment, with hand paddles, with parachute and with hand paddles + parachute. Arm and leg stroke phases were identified by 2D video analysis to calculate the total time gap (T1: time between hands' entry in the water and high break-even point of the first undulation; T2: time between the beginning of the hand's backward movement and low break-even point of the first undulation; T3: time between the hand's arrival in a vertical plane to the shoulders and high break-even point of the second undulation; T4: time between the hand's release from the water and low break-even point of the second undulation). The swimming velocity was reduced and T1, T2 and T3 increased in parachute and hand paddles + parachute. No changes were observed in T4. Total time gap decreased in parachute and hand paddles + parachute. It is concluded that hand paddles do not influence the arm-to-leg coordination in butterfly, while parachute and hand paddles + parachute do change it, providing a greater propulsive continuity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

CARR,R.; CORNACCHIA,M.; EMMA,P.

The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show Self Amplified Spontaneous Emission (SASE) to saturation in the visible light energy range. It will generate a resonant wavelength output from 800--600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to reach saturation, and its diagnostics will provide important checks of theory. This paper includes a description of the VISA undulator, the magnet measuring and shimming system, and the alignment strategy. VISA will have a 4 m pure permanent magnet undulatormore » comprising four 99 cm segments, each with 55 periods of 18 mm length. The undulator has distributed focusing built into it, to reduce the average beta function of the 70--85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walkoff or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, the authors expect to be able to control trajectory walkoff to less than {+-}50 pm per field gain length.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, R.; Cornacchia, M.; Emma, P.

The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show Self Amplified Spontaneous Emission (SASE) to saturation in the visible light energy range. It will generate a resonant wavelength output from 800--600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to reach saturation, and its diagnostics will provide important checks of theory. This paper includes a description of the VISA undulator, the magnet measuring and shimming system, and the alignment strategy. VISA will have a 4 m pure permanent magnet undulatormore » comprising four 99 cm segments, each with 55 periods of 18 mm length. The undulator has distributed focusing built into it, to reduce the average beta function of the 70--85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walkoff, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, the authors expect to be able to control trajectory walkoff to less than {+-}50 {micro}m per field gain length.« less

Modeling and estimation of a low degree geopotential model from terrestrial gravity data

NASA Technical Reports Server (NTRS)

Pavlis, Nikolaos K.

1988-01-01

The development of appropriate modeling and adjustment procedures for the estimation of harmonic coefficients of the geopotential, from surface gravity data was studied, in order to provide an optimum way of utilizing the terrestrial gravity information in combination solutions currently developed at NASA/Goddard Space Flight Center, for use in the TOPEX/POSEIDON mission. The mathematical modeling was based on the fundamental boundary condition of the linearized Molodensky boundary value problem. Atmospheric and ellipsoidal corrections were applied to the surface anomalies. Terrestrial gravity solutions were found to be in good agreement with the satellite ones over areas which are well surveyed (gravimetrically), such as North America or Australia. However, systematic differences between the terrestrial only models and GEMT1, over extended regions in Africa, the Soviet Union, and China were found. In Africa, gravity anomaly differences on the order of 20 mgals and undulation differences on the order of 15 meters, over regions extending 2000 km in diameter, occur. Comparisons of the GEMT1 implied undulations with 32 well distributed Doppler derived undulations gave an RMS difference of 2.6 m, while corresponding comparison with undulations implied by the terrestrial solution gave RMS difference on the order of 15 m, which implies that the terrestrial data in that region are substantially in error.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasaki, S.; McNulty, I.; Shimada, T.

We investigate use of an APPLE-type undulator for generating Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) mode beams. We find that the second harmonic radiation in the circular mode corresponds to an LG beam with l=1, and the second harmonic in the linear mode corresponds to an HG beam with l=1. The combination of an APPLE undulator and conventional monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community.

Soft X-ray FEL simulation in PAL-XFEL

NASA Astrophysics Data System (ADS)

Shim, Chi Hyun; Ko, In Soo; Parc, Yong Woon; Han, Jang Hui

2015-10-01

The soft X-ray beamline in the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) will provide a photon beam with a wavelength from 1 nm to 3 nm in the self-amplified spontaneous emission (SASE) mode by using an electron beam with a 3.15-GeV beam energy. Linearly polarized radiation will be supplied by using six planar undulators (PUs). The linearly-polarized radiation powers at 1 (3) nm can reach 10.2 (30) GW. Polarization of the radiation will be controlled by applying the reverse undulator tapering scheme to the PUs and adding two helical undulators (HUs). The circularly-polarized radiation powers at 1 (3) nm will be 3.11 (11.73) GW. The degrees of circular polarization will be larger than 0.99 for both wavelengths. Three options for the future upgrade of the beamline to increase the radiation power are proposed.

Detecting spatial patterns of rivermouth processes using a geostatistical framework for near-real-time analysis

USGS Publications Warehouse

Xu, Wenzhao; Collingsworth, Paris D.; Bailey, Barbara; Carlson Mazur, Martha L.; Schaeffer, Jeff; Minsker, Barbara

2017-01-01

This paper proposes a geospatial analysis framework and software to interpret water-quality sampling data from towed undulating vehicles in near-real time. The framework includes data quality assurance and quality control processes, automated kriging interpolation along undulating paths, and local hotspot and cluster analyses. These methods are implemented in an interactive Web application developed using the Shiny package in the R programming environment to support near-real time analysis along with 2- and 3-D visualizations. The approach is demonstrated using historical sampling data from an undulating vehicle deployed at three rivermouth sites in Lake Michigan during 2011. The normalized root-mean-square error (NRMSE) of the interpolation averages approximately 10% in 3-fold cross validation. The results show that the framework can be used to track river plume dynamics and provide insights on mixing, which could be related to wind and seiche events.

DOE Office of Scientific and Technical Information (OSTI.GOV)

He Yongzhou; Zhang Jidong; Zhou Qiaogen

Two in-vacuum undulators IVU25s and one elliptically polarized undulator EPU100 have been developed for SSRF. Two IVU25s with the same hybrid design contain about 640 Sm{sub 2}Co{sub 17} magnet blocks and the dimension of blocks is 65 Wx25 Hx9 D. The EPU100 of the APPLE-II type contains about 690 NdFeB magnet blocks with the dimension of 35 Wx35 Hx25 D. This paper describes the magnetic measurements of these magnet blocks with the Helmholtz coil measurement system for IVU25 magnet blocks and the Hall probe measurement system for EPU100 magnet blocks. The measured maximum magnetic moment deviation and the maximum anglemore » deviation are less than {+-}1.0% and 1.1 deg. respectively both for Sm{sub 2}Co{sub 17} blocks and NdFeB blocks and satisfy the specifications of undulators.« less

Properties of the insertion devices for PETRA III and its extension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schöps, A., E-mail: andreas.schoeps@desy.de; Vagin, P.; Tischer, M., E-mail: markus.tischer@desy.de

DESY presently operates 14 independent insertion device (ID) beamlines at its 6 GeV storage ring PETRA III. Besides the 2 m long standard undulators U29 and U32, several special IDs of up to 5 m length have been installed to meet the experimental requests for high energy X-rays, elliptically polarized light, and a higher degree of coherence. Two additional half octants of the ring have recently been reconstructed, in order to extend the experimental capabilities at PETRA III. The straight sections also allow for installation of IDs of 2 m or 5 m length. This article gives an overview ofmore » the ID key parameters, the spectral properties and the brilliance of the current undulators installed at PETRA III. It also presents the characteristics of some of the upcoming special IDs, like in-vacuum and short undulators.« less

Compact representations of partially coherent undulator radiation suitable for wave propagation

DOE PAGES

Lindberg, Ryan R.; Kim, Kwang -Je

2015-09-28

Undulator radiation is partially coherent in the transverse plane, with the degree of coherence depending on the ratio of the electron beam phase space area (emittance) to the characteristic radiation wavelength λ. Numerical codes used to predict x-ray beam line performance can typically only propagate coherent fields from the source to the image plane. We investigate methods for representing partially coherent undulator radiation using a suitably chosen set of coherent fields that can be used in standard wave propagation codes, and discuss such “coherent mode expansions” for arbitrary degrees of coherence. In the limit when the electron beam emittance alongmore » at least one direction is much larger than λ the coherent modes are orthogonal and therefore compact; when the emittance approaches λ in both planes we discuss an economical method of defining the relevant coherent fields that samples the electron beam phase space using low-discrepancy sequences.« less

Research on the effects of geometrical and material uncertainties on the band gap of the undulated beam

NASA Astrophysics Data System (ADS)

Li, Yi; Xu, Yanlong

2017-09-01

Considering uncertain geometrical and material parameters, the lower and upper bounds of the band gap of an undulated beam with periodically arched shape are studied by the Monte Carlo Simulation (MCS) and interval analysis based on the Taylor series. Given the random variations of the overall uncertain variables, scatter plots from the MCS are used to analyze the qualitative sensitivities of the band gap respect to these uncertainties. We find that the influence of uncertainty of the geometrical parameter on the band gap of the undulated beam is stronger than that of the material parameter. And this conclusion is also proved by the interval analysis based on the Taylor series. Our methodology can give a strategy to reduce the errors between the design and practical values of the band gaps by improving the accuracy of the specially selected uncertain design variables of the periodical structures.

The GALAXIE all-optical FEL project

NASA Astrophysics Data System (ADS)

Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O'Shea, B.; O'Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M.; Tantawi, S.; Valloni, A.; Yakimenko, V.; Xu, G.

2012-12-01

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 μm laser development, ultra-high brighness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

Waveguide-Mode Terahertz Free Electron Lasers Driven by Magnetron-Based Microtrons

NASA Astrophysics Data System (ADS)

Jeong, Young Uk; Miginsky, Sergey; Gudkov, Boris; Lee, Kitae; Mun, Jungho; Shim, Gyu Il; Bae, Sangyoon; Kim, Hyun Woo; Jang, Kyu-Ha; Park, Sunjeong; Park, Seong Hee; Vinokurov, Nikolay

2016-04-01

We have developed small-sized terahertz free-electron lasers by using low-cost and compact microtrons combining with magnetrons as high-power RF sources. We could stabilize the bunch repetition rate by optimizing a modulator for the magnetron and by coupling the magnetron with an accelerating cavity in the microtron. By developing high-performance undulators and low-loss waveguide-mode resonators having small cross-sectional areas, we could strengthen the interaction between the electron beam and the THz wave inside the FEL resonators to achieve lasing even with low-current electron beams from the microtron. We used a parallel-plate waveguide in a planar electromagnet undulator for our first THz FEL. We try to reduce the size of the FEL resonator by combining a dielectric-coated circular waveguide and a variable-period helical undulator to realize a table-top THz FEL for applying it to the security inspection on airports.

A possible upgrade of FLASH for harmonic lasing down to 1.3 nm

NASA Astrophysics Data System (ADS)

Schneidmiller, E. A.; Yurkov, M. V.

2013-07-01

We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. With the help of numerical simulations we demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 1031 photons/(s mrad2 mm2 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation. We also discuss possible technical issues and backup solutions.

Undulations on the surface of elongated bubbles in confined gas-liquid flows

NASA Astrophysics Data System (ADS)

Magnini, M.; Ferrari, A.; Thome, J. R.; Stone, H. A.

2017-08-01

A systematic analysis is presented of the undulations appearing on the surface of long bubbles in confined gas-liquid flows. CFD simulations of the flow are performed with a self-improved version of the open-source solver ESI OpenFOAM (release 2.3.1), for Ca =0.002 -0.1 and Re =0.1 -1000 , where Ca =μ U /σ and Re =2 ρ U R /μ , with μ and ρ being, respectively, the viscosity and density of the liquid, σ the surface tension, U the bubble velocity, and R the tube radius. A model, based on an extension of the classical axisymmetric Bretherton theory, accounting for inertia and for the curvature of the tube's wall, is adopted to better understand the CFD results. The thickness of the liquid film, and the wavelength and decay rate of the undulations extracted from the CFD simulations, agree well with those obtained with the theoretical model. Inertial effects appear when the Weber number of the flow We =Ca Re =O (10-1) and are manifest by a larger number of undulation crests that become evident on the surface of the rear meniscus of the bubble. This study demonstrates that the necessary bubble length for a flat liquid film region to exist between the rear and front menisci rapidly increases above 10 R when Ca >0.01 and the value of the Reynolds number approaches 1000.

Results of animal experiments using an undulation pump total artificial heart: analysis of 10 day and 19 day survival.

PubMed

Mochizuki, S; Abe, Y; Chinzei, T; Isoyama, T; Ono, T; Saito, I; Guba, P; Karita, T; Sun, Y P; Kouno, A; Suzuki, T; Baba, K; Mabuchi, K; Imachi, K

2000-01-01

An undulation pump is a special rotary blood pump in which rotation of a brushless DC motor is transformed to an undulating motion by a disc in the pump housing attached by means of a special link mechanism. In the blood pump, a closed line between the disc and housing moves from the inlet to the outlet by this undulating disc motion, which sucks and pushes the blood from the inlet to the outlet. Because the same phenomena occurs at both sides of the disc, a continuous flow is obtained when the motor rotational speed is constant. The pump flow pattern can be easily changed from continuous flow to pulsatile flow by controlling the motor drive current pattern. A seal membrane made of segmented polyurethane protects the blood from invading the link mechanism as well as the motor. UPTAH is fabricated with two undulation pumps and two brushless DC motors. Its size is 75 mm in diameter and 80 mm long, and it has one of the great advantage of no compliance chamber required in the system. UPTAHs were implanted under cardiopulmonary bypass (CPB) into the chest cavities of 16 goats, each weighing between 41 and 72 kg. No anticoagulant and antiplatelet agent was used after the surgery. The left atrial pressure was automatically controlled to prevent its elevation and sucking of the atrial wall into the atrial cuff. The following results were obtained: (1) UPTAHs fit well into all the goats; (2) the longest survival was 19.8 days, the cause of death was bleeding from the aortic anastomosis; (3) No thrombus was observed in the blood pump despite no anticoagulant use. Hemolysis depended upon the length of CPB during surgery. When CPB time was within 2 hours, hemolysis level returned to baseline within a few days of the surgery. UPTAH is a promising implantable TAH, because of its small size and easy controllability.

A helical optical for circular polarized UV-FEL project at the UVSOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hama, Hiroyuki

1995-12-31

Most of existing storage ring free electron lasers (SRFEL) are restricted those performances by degradation of mirrors in optical cavities. In general, the SRFEL gain at the short wavelength region with high energy electrons is quite low, and the high reflectivity mirrors such as dielectric multilayer mirrors are therefore required. The mirror degradation is considered as a result of irradiation of higher harmonic photons that are simultaneously emitted from planar optical klystron (OK) type undulators, which are commonly used in SRFEL. This problem is getting severer as the lasing wavelength becomes shorter. The UVSOR-FEL had been originally scheduled to bemore » shutdown by 1996 because another undulator project for spectroscopic studies with circular polarized photon would take the FEL`s place. According to suggestion of the insertion device group of the SPring-8, we have designed a helical undulator that is able to vary degree and direction of the polarization easily. In addition, the undulator can be converted into a helical OK by replacing magnets at the center part of undulator in order to coexist with further FEL experiments. Using a calculated magnetic field for magnet configurations of the OK mode, the radiation spectrum at wide wavelength range was simulated by a Fourier transform of Lienard-Wiechert potentials. As a matter of course, some higher harmonics are radiated on the off-axis angle. However it was found out that the higher harmonics is almost negligible as far as inside a solid angle of the Gaussian laser mode. Moreover the gain at the UV region of 250 nm is expected to be much higher than our present FEL because of high brilliant fundamental radiation. The calculated spatial distribution of higher harmonics and the estimated instantaneous gain is presented. Advantages of the helical OK for SRFEL will be discussed in view of our experience, and a possibility of application two-color experiment with SR will be also mentioned.« less

Influence of higher harmonics of the undulator in X-ray polarimetry and crystal monochromator design.

PubMed

Marx-Glowna, Berit; Schulze, Kai S; Uschmann, Ingo; Kämpfer, Tino; Weber, Günter; Hahn, Christoph; Wille, Hans Christian; Schlage, Kai; Röhlsberger, Ralf; Förster, Eckhart; Stöhlker, Thomas; Paulus, Gerhard G

2015-09-01

The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel-cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahrdt, J.; Frentrup, W.; Gaupp, A.

BESSY plans to build a SASE-FEL facility for the energy range from 20 eV to 1000 eV. The energy range will be covered by three APPLE II type undulators with a magnetic length of about 60 m each. This paper summarizes the basic parameters of the FEL-undulators. The magnetic design will be presented. A modified APPLE II design will be discussed which provides higher fields at the expense of reduced horizontal access. GENESIS simulations give an estimate on the tolerances for the beam wander and for gap errors.

Spontaneous and amplified radiation at the initial stage of a SASE FEL.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Z.; Kim, K.-J.

At the initial stage of a self-amplified spontaneous emission (SASE) free-electron laser (FEL), spontaneous undulator radiation in certain experimental configurations can dominate the amplified signal over an extended undulator distance. In this paper they study both the spontaneous and the amplified radiation in the framework of the paraxial wave equation and determine the transition from the dominance of spontaneous emission to exponential amplification. They compare theoretical expectations with SASE simulation codes GINGER and GENESIS.

Collimation study for LCLS

DOE PAGES

Marin, E.; Raubenhaimer, T.; Welch, J.; ...

2017-06-13

In this study we investigate the power deposition along the undulator section of the SLAC Linac Coherent Light Source (LCLS) due to the primary e¯ -beam but also due to potential secondary particles. The expected beam distribution after the LCLS injector is deliberately broadened as an approximated representation of the beam halo. Secondary particles, as e +, e¯ and photons, are generated as a result of tracking the intercepted beam through a dense material. This process is carried out by means of GEANT-4, which has been convoluted into our main tracking engine, LUCRETIA. Simulations show no losses along the undulatormore » section when assuming the nominal primary beam and collimator gaps. However when opening the gaps of collimators located at the first collimator section, by 25%, the fattened beam is partially intercepted by the second collimator section, which is aligned to the undulators. Secondary particles, mostly photons generated at the second collimator section, deposit their energy along the undulator section, at a rate of the order of a milliwatt.« less

Cryogenic Field Measurement of Pr2Fe14B Undulator and Performance Enhancement Options at the NSLS-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanabe, T.; Chubar, O.; Harder, David A.

2009-09-27

Short period (14.5mm) hybrid undulator arrays composed of Praseodymium Iron Boron (Pr{sub 2}Fe{sub 14}B) magnets (CR53, NEOMAX, Inc.) and vanadium permendur poles have been fabricated at Brookhaven National Laboratory. Unlike Neodymium Iron Boron (Nd{sub 2}Fe{sub 14}B) magnets which exhibit spin reorientation at temperatures below 150K, PrFeB arrays monotonically increase performance with lower operating temperature. It opens up the posibility for use in operating a cryo-permanent magnet undulator (CPMU) in the range of 40K to 60K where very efficient cryocoolers are available. Magnetic flux density profiles were measured at various temperature ranges from room temperature down to liquid helium (LHe) usingmore » the Vertical Testing Facility (VTF) at the National Snchrotron Light Source-II (NSLS-II). Temperature variations of phase error have been characterized. In addition, we examined the use of textured Dysprosium (Dy) poles to replace permendur poles to obtain further improvement in performance.« less

The GALAXIE all-optical FEL project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenzweig, J. B.; Arab, E.; Andonian, G.

2012-12-21

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-highmore » brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.« less

Eigenmode analysis of a high-gain free-electron laser based on a transverse gradient undulator

DOE PAGES

Baxevanis, Panagiotis; Huang, Zhirong; Ruth, Ronald; ...

2015-01-27

Here, the use of a transverse gradient undulator (TGU) is viewed as an attractive option for free-electron lasers (FELs) driven by beams with a large energy spread. By suitably dispersing the electron beam and tilting the undulator poles, the energy spread effect can be substantially mitigated. However, adding the dispersion typically leads to electron beams with large aspect ratios. As a result, the presence of higher-order modes in the FEL radiation can become significant. To investigate this effect, we study the eigenmode properties of a TGU-based, high-gain FEL, using both an analytically-solvable model and a variational technique. Our analysis, whichmore » includes the fundamental and the higher-order FEL eigenmodes, can provide an estimate of the mode content for the output radiation. This formalism also enables us to study the trade-off between FEL gain and transverse coherence. Numerical results are presented for a representative soft X-ray, TGU FEL example.« less

The influence of tyre transient side force properties on vehicle lateral acceleration for a time-varying vertical force

NASA Astrophysics Data System (ADS)

Takahashi, Toshimichi

2018-05-01

The tyre model which formerly developed by the author et al. and describes the tyre transient responses of side force and aligning moment under the time-varying vertical force was implemented to the vehicle dynamics simulation software and the influence of tyre side force transient property on the vehicle behaviour was investigated. The vehicle responses with/without tyre transient property on sinusoidally undulated road surfaces were simulated and compared. It was found that the average lateral acceleration of the vehicle at the sinusoidal steering wheel angle input decreases on the undulated road of long wavelength (3 m) for both cases, but when the wavelength becomes shorter (1 m), the average lateral acceleration increases only in the case that the transient property is considered. The cause of those changes is explained by using the tyre-related variables. Also the steady-state turning behaviour of the vehicle on undulated roads are shown and discussed.

Eigenmode analysis of a high-gain free-electron laser based on a transverse gradient undulator

NASA Astrophysics Data System (ADS)

Baxevanis, Panagiotis; Huang, Zhirong; Ruth, Ronald; Schroeder, Carl B.

2015-01-01

The use of a transverse gradient undulator (TGU) is viewed as an attractive option for free-electron lasers (FELs) driven by beams with a large energy spread. By suitably dispersing the electron beam and tilting the undulator poles, the energy spread effect can be substantially mitigated. However, adding the dispersion typically leads to electron beams with large aspect ratios. As a result, the presence of higher-order modes in the FEL radiation can become significant. To investigate this effect, we study the eigenmode properties of a TGU-based, high-gain FEL, using both an analytically-solvable model and a variational technique. Our analysis, which includes the fundamental and the higher-order FEL eigenmodes, can provide an estimate of the mode content for the output radiation. This formalism also enables us to study the trade-off between FEL gain and transverse coherence. Numerical results are presented for a representative soft X-ray, TGU FEL example.

Nonlinear Phase Distortion in a Ti:Sapphire Optical Amplifier for Optical Stochastic Cooling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andorf, Matthew; Lebedev, Valeri; Piot, Philippe

2016-06-01

Optical Stochastic Cooling (OSC) has been considered for future high-luminosity colliders as it offers much faster cooling time in comparison to the micro-wave stochastic cooling. The OSC technique relies on collecting and amplifying a broadband optical signal from a pickup undulator and feeding the amplified signal back to the beam. It creates a corrective kick in a kicker undulator. Owing to its superb gain qualities and broadband amplification features, Titanium:Sapphire medium has been considered as a gain medium for the optical amplifier (OA) needed in the OSC*. A limiting factor for any OA used in OSC is the possibility ofmore » nonlinear phase distortions. In this paper we experimentally measure phase distortions by inserting a single-pass OA into one leg of a Mach-Zehnder interferometer. The measurement results are used to estimate the reduction of the corrective kick a particle would receive due to these phase distortions in the kicker undulator.« less

A transverse bunch by bunch feedback system for Pohang Light Source upgrade

NASA Astrophysics Data System (ADS)

Lee, E.-H.; Kim, D.-T.; Huang, J.-Y.; Shin, S.; Nakamura, T.; Kobayashi, K.

2014-12-01

The Pohang Light Source upgrade (PLS-II) project has successfully upgraded the Pohang Light Source (PLS). The main goals of the PLS-II project are to increase the beam energy to 3 GeV, increase the number of insertion devices by a factor of two (20 IDs), increase the beam current to 400 mA, and at the same time reduce the beam emittance to below 10 nm by using the existing PLS tunnel and injection system. Among 20 insertion devices, 10 narrow gap in-vacuum undulators are in operation now and two more in-vacuum undulators are to be installed later. Since these narrow gap in-vacuum undulators are most likely to produce coupled bunch instability by the resistive wall impedance and limit the stored beam current, a bunch by bunch feedback system is implemented to suppress coupled bunch instability in the PLS-II. This paper describes the scheme and performance of the PLS-II bunch by bunch feedback system.

Quasi-planer-laminated sandstone beds of the Lower Cretaceous Bootlegger Member, north-central Montana: Evidence of combined-flow sedimentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arnott, R.W.C.

1993-05-01

Lower-shoreface to shallow-shelf strata of the Bootlegger Member of the Lower Cretaceous Blackleaf Formation are characterized by interbedded sandstone and mudstone. Sandstone beds are characterized by a peculiar planar lamination showing a subtle although perceptible undulation; spacing-to-height ratios of the undulation are generally 100 or more. Typically the undulation shows no evidence of lateral accretion but only vertical aggradation, and as a result most beds consist of a single laminaset. Aspects of quasi-planar-laminated beds indicate single-event storm sedimentation, and paleocurrent data indicate offshore sediment transport. By its sedimentary characteristics and its similarity with a bed configuration generated in an experimentalmore » wave duct, quasi-planar lamination is produced by high-energy combined flows. This style of stratification should be common in the shallow-marine stratigraphic record, and its recognition should aid in interpreting high-energy, combined-flow depositional events.« less

The study about forming high-precision optical lens minimalized sinuous error structures for designed surface

NASA Astrophysics Data System (ADS)

Katahira, Yu; Fukuta, Masahiko; Katsuki, Masahide; Momochi, Takeshi; Yamamoto, Yoshihiro

2016-09-01

Recently, it has been required to improve qualities of aspherical lenses mounted on camera units. Optical lenses in highvolume production generally are applied with molding process using cemented carbide or Ni-P coated steel, which can be selected from lens material such as glass and plastic. Additionally it can be obtained high quality of the cut or ground surface on mold due to developments of different mold product technologies. As results, it can be less than 100nmPV as form-error and 1nmRa as surface roughness in molds. Furthermore it comes to need higher quality, not only formerror( PV) and surface roughness(Ra) but also other surface characteristics. For instance, it can be caused distorted shapes at imaging by middle spatial frequency undulations on the lens surface. In this study, we made focus on several types of sinuous structures, which can be classified into form errors for designed surface and deteriorate optical system performances. And it was obtained mold product processes minimalizing undulations on the surface. In the report, it was mentioned about the analyzing process by using PSD so as to evaluate micro undulations on the machined surface quantitatively. In addition, it was mentioned that the grinding process with circumferential velocity control was effective for large aperture lenses fabrication and could minimalize undulations appeared on outer area of the machined surface, and mentioned about the optical glass lens molding process by using the high precision press machine.

The effect of traveling wave shapes in the maneuver control and efficiency of an underwater robot propelled by an undulating fin

NASA Astrophysics Data System (ADS)

Liu, Hanlin; Curet, Oscar

2016-11-01

Effective control of propulsive undulating fins has the potential to enhance the maneuverability and efficiency of underwater vehicles allowing them to navigate in more complex environments. Aquatic animals using this type of propulsion are able to perform complex maneuvers by sending different traveling waves along one or multiple elongated fins. Recent work has investigated the propulsive forces, the hydrodynamics and the efficiency of an undulating ribbon fin. However, it is still not understood how different traveling wave shapes along the fin can be used to control the hydrodynamic forces and torques to perform different maneuvers. In this work, we study the effect of traveling wave shapes on the hydrodynamic forces and torques, swimming speed, maneuver control and propulsive performance of an underwater vehicle propelled by an undulating fin. The underwater robot propels by actuating a fin that is composed of sixteen independent rays interconnected with a flexible membrane. The hull contains all the electronics, batteries, motors and sensors. The underwater vehicle was tested in a water tank-flume facility. In a series of experiments, we measured the motion of the vessel and the power consumption for different traveling wave patterns. In addition, we measured the flow around the fin using Particle Image Velocimetry. We present the results concerning the power distribution along the fin, propulsive efficiency, free-swimming speed and pitch control based on different fin kinematics. National Science Foundation under Grant No. 1420774.

Single shot polarization characterization of XUV FEL pulses from crossed polarized undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrari, E.; Allaria, E.; Buck, J.

Polarization control is a key feature of light generated by short-wavelength free-electron lasers. In this work, we report the first experimental characterization of the polarization properties of an extreme ultraviolet high gain free-electron laser operated with crossed polarized undulators. We research the average degree of polarization and the shot-to-shot stability and we analyze aspects such as existing possibilities for controlling and switching the polarization state of the emitted light. The results are in agreement with predictions based on Gaussian beams propagation.

Modular approach to achieving the next-generation X-ray light source

NASA Astrophysics Data System (ADS)

Biedron, S. G.; Milton, S. V.; Freund, H. P.

2001-12-01

A modular approach to the next-generation light source is described. The "modules" include photocathode, radio-frequency, electron guns and their associated drive-laser systems, linear accelerators, bunch-compression systems, seed laser systems, planar undulators, two-undulator harmonic generation schemes, high-gain harmonic generation systems, nonlinear higher harmonics, and wavelength shifting. These modules will be helpful in distributing the next-generation light source to many more laboratories than the current single-pass, high-gain free-electron laser designs permit, due to both monetary and/or physical space constraints.

Single shot polarization characterization of XUV FEL pulses from crossed polarized undulators

DOE PAGES

Ferrari, E.; Allaria, E.; Buck, J.; ...

2015-08-28

Polarization control is a key feature of light generated by short-wavelength free-electron lasers. In this work, we report the first experimental characterization of the polarization properties of an extreme ultraviolet high gain free-electron laser operated with crossed polarized undulators. We research the average degree of polarization and the shot-to-shot stability and we analyze aspects such as existing possibilities for controlling and switching the polarization state of the emitted light. The results are in agreement with predictions based on Gaussian beams propagation.

Elasticity of a soap film junction

NASA Astrophysics Data System (ADS)

Elias, F.; Janiaud, E.; Bacri, J.-C.; Andreotti, B.

2014-03-01

We investigate the elasticity of an isolated, threefold junction of soap films (Plateau border), which displays static undulations when liquid rapidly flows into it. By analyzing the shape of the Plateau border (thickness R and transverse displacement) as a function of the liquid flow rate Q, we show experimentally and theoretically that the elasticity of the Plateau border is dominated by the bending of the soap films pulling on the Plateau border. In this asymptotic regime, the undulation wavelength obeys the scaling law ˜Q2 R-2 and the decay length ˜Q2 R-4.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, Roger

The VISA (Visible to Infrared SASE Amplifier) FEL is designed to obtain high gain at a radiation wavelength of 800nm. The FEL uses the high brightness electron beam of the Accelerator Test Facility (ATF), with energy of 72MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6mm and a period of 1.8cm. To obtain large gain the beam and undulator axis have to be aligned to better than 50{micro}m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations.

The radio power reflected from rough and undulating ionospheric surfaces

NASA Astrophysics Data System (ADS)

Whitehead, J. D.; From, W. R.; Smith, L. G.

1984-08-01

It is shown for both rough and undulating surfaces that the mean radio power reflected by the ionosphere averaged over a sufficiently long time is exactly the same as for a smooth flat surface at the same height provided the sounder is equally sensitive for echoes from all directions. When making radio wave absorption measurements under spread conditions the total integrated power over the whole time the direct echoes are being received must be used but the distance attenuation factor must be calculated from the time of arrival of the first echo.

How kelp produce blade shapes suited to different flow regimes: A new wrinkle.

PubMed

Koehl, M A R; Silk, W K; Liang, H; Mahadevan, L

2008-12-01

Many species of macroalgae have flat, strap-like blades in habitats exposed to rapidly flowing water, but have wide, ruffled "undulate" blades at protected sites. We used the giant bull kelp, Nereocystis luetkeana, to investigate how these ecomorphological differences are produced. The undulate blades of N. luetkeana from sites with low flow remain spread out and flutter erratically in moving water, thereby not only enhancing interception of light, but also increasing drag. In contrast, strap-like blades of kelp from habitats with rapid flow collapse into streamlined bundles and flutter at low amplitude in flowing water, thus reducing both drag and interception of light. Transplant experiments in the field revealed that shape of the blade in N. luetkeana is a plastic trait. Laboratory experiments in which growing blades from different sites were subjected to tensile forces that mimicked the hydrodynamic drag experienced by blades in different flow regimes showed that change in shape is induced by mechanical stress. During growth experiments in the field and laboratory, we mapped the spatial distribution of growth in both undulate and strap-like blades to determine how these different morphologies were produced. The highest growth rates occur near the proximal ends of N. luetkeana blades of both morphologies, but the rates of transverse growth of narrow, strap-like blades are lower than those of wide, undulate blades. If rates of longitudinal growth at the edges of a blade exceed the rate of longitudinal growth along the midline of the blade, ruffles along the edges of the blade are produced by elastic buckling. In contrast, flat blades are produced when rates of longitudinal growth are similar across the width of a blade. Because ruffles are the result of elastic buckling, a compliant undulate N. luetkeana blade can easily be pushed into different configurations (e.g., the wavelengths of the ruffles along the edges of the blade can change, and the whole blade can twist into left- and right-handed helicoidal shapes), which may enhance movements of the blade in flowing water that reduce self-shading and increase mass exchange along blade surfaces.

Large-area homogeneous periodic surface structures generated on the surface of sputtered boron carbide thin films by femtosecond laser processing

NASA Astrophysics Data System (ADS)

Serra, R.; Oliveira, V.; Oliveira, J. C.; Kubart, T.; Vilar, R.; Cavaleiro, A.

2015-03-01

Amorphous and crystalline sputtered boron carbide thin films have a very high hardness even surpassing that of bulk crystalline boron carbide (≈41 GPa). However, magnetron sputtered B-C films have high friction coefficients (C.o.F) which limit their industrial application. Nanopatterning of materials surfaces has been proposed as a solution to decrease the C.o.F. The contact area of the nanopatterned surfaces is decreased due to the nanometre size of the asperities which results in a significant reduction of adhesion and friction. In the present work, the surface of amorphous and polycrystalline B-C thin films deposited by magnetron sputtering was nanopatterned using infrared femtosecond laser radiation. Successive parallel laser tracks 10 μm apart were overlapped in order to obtain a processed area of about 3 mm2. Sinusoidal-like undulations with the same spatial period as the laser tracks were formed on the surface of the amorphous boron carbide films after laser processing. The undulations amplitude increases with increasing laser fluence. The formation of undulations with a 10 μm period was also observed on the surface of the crystalline boron carbide film processed with a pulse energy of 72 μJ. The amplitude of the undulations is about 10 times higher than in the amorphous films processed at the same pulse energy due to the higher roughness of the films and consequent increase in laser radiation absorption. LIPSS formation on the surface of the films was achieved for the three B-C films under study. However, LIPSS are formed under different circumstances. Processing of the amorphous films at low fluence (72 μJ) results in LIPSS formation only on localized spots on the film surface. LIPSS formation was also observed on the top of the undulations formed after laser processing with 78 μJ of the amorphous film deposited at 800 °C. Finally, large-area homogeneous LIPSS coverage of the boron carbide crystalline films surface was achieved within a large range of laser fluences although holes are also formed at higher laser fluences.

Cryogenic Field Measurement of Pr{sub 2}Fe{sub 14}B Undulator and Performance Enhancement Options at the NSLS-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanabe, Toshiya; Chubar, Oleg; Harder, David A.

2010-06-23

Short period (14.5mm) hybrid undulator arrays composed of Praseodymium Iron Boron (Pr{sub 2}Fe{sub 14}B) magnets (CR53, NEOMAX, Inc.) and vanadium permendur poles have been fabricated at Brookhaven National Laboratory. Unlike Neodymium Iron Boron (Nd{sub 2}Fe{sub 14}B) magnets which exhibit spin reorientation at a temperatures below 150 K, PrFeB arrays monotonically increase performance with lower operating temperature. It opens up the possibility for use in operating a cryo-permanent magnet undulator (CPMU) in the range of 40 K to 60 K where very efficient cryocoolers are available. Magnetic flux density profiles were measured at various temperature ranges from room temperature down tomore » liquid helium (LHe) using the Vertical Testing Facility (VTF) at the National Synchrotron Light Source-II (NSLS-II). Temperature variations of phase error have been characterized. In addition, we examined the use of textured Dysprosium (Dy) poles to replace permendur poles to obtain further improvement in performance.« less

Propulsive Forces of a Biomimetic Undulating Fin

NASA Astrophysics Data System (ADS)

Kalumuck, Kenneth; Brandt, Alan; Armand, Mehran

2007-11-01

Understanding gained from much recent work on force production mechanisms of aquatic organisms holds great promise for improved undersea vehicle propulsion and maneuvering. One class of fish locomotion is that of the median fin utilized by animals such as squid, cuttlefish, knifefish, and seahorse. It is characterized by undulatory motion that creates traveling waves along the fin. Results of experiments conducted on a submerged mechanical underwater undulating fin test bed are presented. The 0.5 m long fin is mounted to a cylindrical body and consists of a flexible skin attached to ribs driven by an adjustable cam mechanism and variable speed motor that enables changing the characteristics of the undulating wave(s). Forces produced were measured in a captive mode under quiescent conditions as well in the presence of an ambient current. Propulsive forces are characterized as a function of the fin width, oscillation frequency, amplitude, and wavelength. Free swimming experiments were also conducted to determine the point of self propulsion. Flow field structure visualization using dye tracers is presented for selected cases. Estimates of performance and applications for use with larger scale vehicles are discussed.

The geometry and fluid dynamics of two- and three-dimensional maneuvers of burrowing and swimming C. elegans

NASA Astrophysics Data System (ADS)

Blawzdziewicz, Jerzy; Bilbao, Alejandro; Patel, Amar; Rahman, Mizanur; Vanapalli, Siva A.

2016-11-01

In its natural environment, which is decomposing organic matter and water, C. elegans swims and burrows in 3D complex media. Yet quantitative investigations of C. elegans locomotion have been limited to 2D motion. Recently we have provided a quantitative analysis of turning maneuvers of crawling and swimming nematodes on flat surfaces and in 2D fluid layers. Here, we follow with the first full 3D description of how C. elegans moves in complex 3D environments. We show that the nematode can explore 3D space by combining 2D turns with roll maneuvers that result in rotation of the undulation plane around the direction of motion. Roll motion is achieved by superposing a 2D curvature wave with nonzero body torsion; 2D turns (within the current undulation plane) are attained by variation of undulation wave parameters. Our results indicate that while hydrodynamic interactions reduce angles of 2D turns, the roll efficiency is significantly enhanced. This hydrodynamic effect explains the rapid nematode reorientation observed in 3D swimming.

Current status of BL-2B at photon factory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nambu, Akira, E-mail: akia.nambu.tw@hitachi.com; Ueda, Kazuhiro; Horiba, Koji

A new soft x-ray beamline BL-2B at Photon Factory of High Energy Accelerator Research Organization (KEK-PF) covers energy range from vacuum ultraviolet (30 eV) to soft x-ray (4000 eV). This wide energy range could be achieved by employing two undulators and two monochromators. Two different energy range undulators were installed tandem to a 9-meter straight section of PF storage ring. The 1{sup st} undulator is for VUV (30 eV) to SX (280 eV), while the other one is for SX (280 eV) to HX (4000 eV). It is also necessary to be equipped with two different monochrometors for energy abovemore » and under 2000 eV; grating monochrometor and double crystal monochrometor. One of the main purposes of this bemaline is spectroscopic study of light elements contained in several functional materials. The beamline is designed for photoemission spectroscopy (PES), X-ray absorption fine structure (XAFS) and other types of experiments. The performance of the new beamline is reported and typical examples of its application to material science are demonstrated.« less

Performance of 2G-HTS REBCO undulator coils impregnated epoxies mixed with different fillers

DOE PAGES

Kesgin, Ibrahim; Hasse, Quentin; Ivanyushenkov, Yury; ...

2016-12-12

The use of second-generation high-temperature superconducting-coated conductors enables an enhancement of the performance of undulator magnets. However, preventing the motion of the wire and providing sufficient conduction cooling to the winding stacks have remained challenges. In this study, we have evaluated epoxy impregnation techniques to address these issues. Epoxy resin was prepared with different nanopowders and the effect on the performance of the undulator coil pack was investigated. All epoxy impregnated coils showed smaller n values and some degree of deterioration of the critical current I c. The I c degradation was most pronounced for epoxy mixed with high aspectmore » ratio multiwalled carbon nanotubes (MWCNTs). It has been found that the crack formation in the epoxy results in plastic deformation of the copper stabilizer layer, which causes the underlying ceramic REBCO superconducting layer to crack resulting in degradation of the superconducting tape performance. As a result, careful adjustment of epoxy thickness surrounding the superconductor and the powder ratio in the epoxy eliminate the performance degradation.« less

Multi-dimensional optimization of a terawatt seeded tapered Free Electron Laser with a Multi-Objective Genetic Algorithm

DOE PAGES

Wu, Juhao; Hu, Newman; Setiawan, Hananiel; ...

2016-11-20

There is a great interest in generating high-power hard X-ray Free Electron Laser (FEL) in the terawatt (TW) level that can enable coherent diffraction imaging of complex molecules like proteins and probe fundamental high-field physics. A feasibility study of producing such X-ray pulses was carried out in this paper employing a configuration beginning with a Self-Amplified Spontaneous Emission FEL, followed by a “self-seeding” crystal monochromator generating a fully coherent seed, and finishing with a long tapered undulator where the coherent seed recombines with the electron bunch and is amplified to high power. The undulator tapering profile, the phase advance inmore » the undulator break sections, the quadrupole focusing strength, etc. are parameters to be optimized. A Genetic Algorithm (GA) is adopted for this multi-dimensional optimization. Concrete examples are given for LINAC Coherent Light Source (LCLS) and LCLS-II-type systems. Finally, analytical estimate is also developed to cross check the simulation and optimization results as a quick and complimentary tool.« less

Optimization Studies of the FERMI at ELETTRA FEL Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Ninno, Giovanni; Fawley, William M.; Penn, Gregory E.

The FERMI at ELETTRA project at Sincotrone Trieste involves two FEL's, each based upon the principle of seeded harmonic generation and using the existing ELETTRA injection linac at 1.2 GeV beam energy. Scheduled to be completed in 2008, FEL-1 will operate in 40-100 nm wavelength range and will involve one stage of harmonic up-conversion. The second undulator line, FEL-2, will begin operation two years later in the 10-40 nm wavelength range and use two harmonic stages operating as a cascade. The FEL design assumes continuous wavelength tunability over the full wavelength range, and polarization tunability of the output radiation includingmore » vertical or horizontal linear as well as helical polarization. The design considers focusing properties and segmentation of realizable undulators and available input seed lasers. We review the studies that have led to our current design. We present results of simulations using GENESIS and GINGER simulation codes including studies of various shot-to-shot fluctuations and undulator errors. Findings for the expected output radiation in terms of the power, transverse and longitudinal coherence are reported.« less

Simulation and measurement of the electrostatic beam kicker in the low-energy undulator test line.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waldschmidt, G. J.

1998-10-27

An electrostatic kicker has been constructed for use in the Low-Energy Undulator Test Line (LEUTL) at the Advanced Photon Source (APS). The function of the kicker is to limit the amount of beam current to be accelerated by the APS linac. Two electrodes within the kicker create an electric field that adjusts the trajectory of the beam. This paper will explore the static fields that are set up between the offset electrode plates and determine the reaction of the beam to this field. The kicker was numerically simulated using the electromagnetic solver package MAFIA [1].

Feasibility of a ring FEL at low emittance storage rings

NASA Astrophysics Data System (ADS)

Agapov, I.

2015-09-01

A scheme for generating coherent radiation at latest generation low emittance storage rings such as PETRA III at DESY (Balewski et al., 2004 [1]) is proposed. The scheme is based on focusing and subsequent defocusing of the electron beam in the longitudinal phase space at the undulator location. The expected performance characteristics are estimated for radiation in the wavelength range of 500-1500 eV. It is shown that the average brightness is increased by several orders of magnitude compared to spontaneous undulator radiation, which can open new perspectives for photon-hungry soft X-ray spectroscopy techniques.

A second-generation superconducting undulator cryostat for the APS

NASA Astrophysics Data System (ADS)

Fuerst, J.; Hasse, Q.; Ivanyushenkov, Y.; Kasa, M.; Shiroyanagi, Y.

2017-12-01

A second-generation cryocooler-based cryostat has been designed and built to support a new helically wound superconducting undulator (SCU) magnet for the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The design represents an evolution of existing SCU cryostats currently in operation in the APS storage ring. Value engineering and lessons learned have resulted in a smaller, cheaper, and simpler cryostat design compatible with existing planar magnets as well as the new helically wound device. We describe heat load and quench response results, design and operational details, and the “build-to-spec” procurement strategy.

An SRRC elliptically polarizing undulator prototype to examine mechanical design feasibility and magnetic field performance.

PubMed

Chang, C H; Hwang, C S; Fan, T C; Chen, K H; Pan, K T; Lin, F Y; Wang, C; Chang, L H; Chen, H H; Lin, M C; Yeh, S

1998-05-01

In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.

Preparing the BESSY APPLE Undulators for Top-Up Operation

NASA Astrophysics Data System (ADS)

Bahrdt, J.; Frentrup, W.; Gaupp, A.; Scheer, M.

2007-01-01

BESSY plans to go to topping up operation in the near future. A high injection efficiency is essential to avoid particle losses inside the undulator magnets and to ensure a low radiation background in the beamlines. Dynamic and static multipoles of the insertion devices have to be minimized to accomplish this requirement. APPLE II devices show strong dynamic multipoles in the elliptical and vertical polarization mode. Measurements before and after shimming of these multipoles are presented. The static multipoles of the BESSY UE56-2 which are due to systematic block inhomgeneities have successfully been shimmed recovering the full dynamic aperture.

Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wootton, Kent

2015-09-17

In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 ± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

Channeling, Volume Reection and Gamma Emission Using 14GeV Electrons in Bent Silicon Crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benson, Brandon

2015-08-14

High energy electrons can be deflected with very tight bending radius using a bent silicon crystal. This produces gamma radiation. As these crystals can be thin, a series of bent silicon crystals with alternating direction has the potential to produce coherent gamma radiation with reasonable energy of the driving electron beam. Such an electron crystal undulator offers the prospect for higher energy radiation at lower cost than current methods. Permanent magnetic undulators like LCLS at SLAC National Accelerator Laboratory are expensive and very large (about 100 m in case of the LCLS undulator). Silicon crystals are inexpensive and compact whenmore » compared to the large magnetic undulators. Additionally, such a high energy coherent light source could be used for probing through materials currently impenetrable by x-rays. In this work we present the experimental data and analysis of experiment T523 conducted at SLAC National Accelerator Laboratory. We collected the spectrum of gamma ray emission from 14 GeV electrons on a bent silicon crystal counting single photons. We also investigated the dynamics of electron motion in the crystal i.e. processes of channeling and volume reflection at 14 GeV, extending and building off previous work. Our single photon spectrum for the amorphous crystal orientation is consistent with bremsstrahlung radiation and the volume reflection crystal orientation shows a trend consistent with synchrotron radiation at a critical energy of 740 MeV. We observe that in these two cases the data are consistent, but we make no further claims because of statistical limitations. We also extended the known energy range of electron crystal dechanneling length and channeling efficiency to 14 GeV.« less

Quasiperiodic field-aligned current dynamics associated with auroral undulations during a substorm recovery

NASA Astrophysics Data System (ADS)

Bunescu, C.; Marghitu, O.; Vogt, J.; Constantinescu, D.; Partamies, N.

2017-03-01

A substorm recovery event in the early morning sector is explored by means of ground and spacecraft data. The ground data are provided by stations of the MIRACLE network, in northern Scandinavia and Svalbard, while spacecraft data are observed by the Cluster satellites, toward the end of the recovery phase. Additional information is provided by the Fast Auroral SnapshoT (FAST) satellite, conjugate to Cluster 3 (C3). A prominent signature in the Cluster data is the low-frequency oscillations of the perturbation magnetic field, in the Pc5 range, interpreted in terms of a motion of quasi-stationary mesoscale field-aligned currents (FACs). Ground magnetic pulsations in the Ps6 range suggest that the Cluster observations are the high-altitude counterpart of the drifting auroral undulations, whose features thus can be explored closely. While multiscale minimum variance analysis provides information on the planarity, orientation, and scale of the FAC structures, the conjugate data from FAST and from the ground stations can be used to resolve also the azimuthal motion. A noteworthy feature of this event, revealed by the Cluster observations, is the apparent relaxation of the twisted magnetic flux tubes, from a sequence of 2-D current filaments to an undulated current sheet, on a timescale of about 10 min. This timescale appears to be consistent with the drift mirror instability in the inner magnetosphere, mapping to the equatorward side of the oval, or the Kelvin-Helmholtz instability related to bursty bulk flows farther downtail, mapping to the poleward side of the oval. However, more work is needed and a better event statistics, to confirm these tentative mechanisms as sources of Ω-like auroral undulations during late substorm recovery.

Fluid dynamics of moving fish in a two-dimensional multiparticle collision dynamics model

NASA Astrophysics Data System (ADS)

Reid, Daniel A. P.; Hildenbrandt, H.; Padding, J. T.; Hemelrijk, C. K.

2012-02-01

The fluid dynamics of animal locomotion, such as that of an undulating fish, are of great interest to both biologists and engineers. However, experimentally studying these fluid dynamics is difficult and time consuming. Model studies can be of great help because of their simpler and more detailed analysis. Their insights may guide empirical work. Particularly the recently introduced multiparticle collision dynamics method may be suitable for the study of moving organisms because it is computationally fast, simple to implement, and has a continuous representation of space. As regards the study of hydrodynamics of moving organisms, the method has only been applied at low Reynolds numbers (below 120) for soft, permeable bodies, and static fishlike shapes. In the present paper we use it to study the hydrodynamics of an undulating fish at Reynolds numbers 1100-1500, after confirming its performance for a moving insect wing at Reynolds number 75. We measure (1) drag, thrust, and lift forces, (2) swimming efficiency and spatial structure of the wake, and (3) distribution of forces along the fish body. We confirm the resemblance between the simulated undulating fish and empirical data. In contrast to theoretical predictions, our model shows that for steadily undulating fish, thrust is produced by the rear 2/3 of the body and that the slip ratio U/V (with U the forward swimming speed and V the rearward speed of the body wave) correlates negatively (instead of positively) with the actual Froude efficiency of swimming. Besides, we show that the common practice of modeling individuals while constraining their sideways acceleration causes them to resemble unconstrained fish with a higher tailbeat frequency.

Accurate determination of the geoid undulation N

NASA Astrophysics Data System (ADS)

Lambrou, E.; Pantazis, G.; Balodimos, D. D.

2003-04-01

This work is related to the activities of the CERGOP Study Group Geodynamics of the Balkan Peninsula, presents a method for the determination of the variation ΔN and, indirectly, of the geoid undulation N with an accuracy of a few millimeters. It is based on the determination of the components xi, eta of the deflection of the vertical using modern geodetic instruments (digital total station and GPS receiver). An analysis of the method is given. Accuracy of the order of 0.01arcsec in the estimated values of the astronomical coordinates Φ and Δ is achieved. The result of applying the proposed method in an area around Athens is presented. In this test application, a system is used which takes advantage of the capabilities of modern geodetic instruments. The GPS receiver permits the determination of the geodetic coordinates at a chosen reference system and, in addition, provides accurate timing information. The astronomical observations are performed through a digital total station with electronic registering of angles and time. The required accuracy of the values of the coordinates is achieved in about four hours of fieldwork. In addition, the instrumentation is lightweight, easily transportable and can be setup in the field very quickly. Combined with a stream-lined data reduction procedure and the use of up-to-date astrometric data, the values of the components xi, eta of the deflection of the vertical and, eventually, the changes ΔN of the geoid undulation are determined easily and accurately. In conclusion, this work demonstrates that it is quite feasible to create an accurate map of the geoid undulation, especially in areas that present large geoid variations and other methods are not capable to give accurate and reliable results.

Waveguide studies for FOM FEM

NASA Astrophysics Data System (ADS)

Best, Robert W.; Urbanus, Wim H.; Verhoeven, Toon (A.)G. A.; Jerby, Eli; Ganzel, Ronit

1993-07-01

A 1 MW cw 200 GHz tunable efficient free electron maser is being designed at the FOM Institute for application in magnetic fusion research. In this paper several waveguide types are considered, including open waveguides. Computer simulations of the amplification and guiding of the mm wave in the undulator are reported. The simulation code is G3DH, written by E. Jerby, which solves a matrix dispersion relation. Gain vs frequency curves are shown. Efficiency calculations indicate that some tapering is needed to reach the desired 1 MW mm wavepower. Simulations of a tapered undulator are presented by Caplan, and overview of the FOM FEM is given by Urbanus et al. at this conference.

Laser-plasma accelerator-based single-cycle attosecond undulator source

NASA Astrophysics Data System (ADS)

Tibai, Z.; Tóth, Gy.; Nagyváradi, A.; Sharma, A.; Mechler, M. I.; Fülöp, J. A.; Almási, G.; Hebling, J.

2018-06-01

Laser-plasma accelerators (LPAs), producing high-quality electron beams, provide an opportunity to reduce the size of free-electron lasers (FELs) to only a few meters. A complete system is proposed here, which is based on FEL technology and consists of an LPA, two undulators, and other magnetic devices. The system is capable to generate carrier-envelope phase stable attosecond pulses with engineered waveform. Pulses with up to 60 nJ energy and 90-400 attosecond duration in the 30-120 nm wavelength range are predicted by numerical simulation. These pulses can be used to investigate ultrafast field-driven electron dynamics in matter.

Installation, commissioning and performance of IDs installed at ALBA

NASA Astrophysics Data System (ADS)

Campmany, J.; Marcos, J.; Massana, V.; Becheri, F.; Gigante, J. V.; Colldelram, C.; Ribó, Ll

2013-03-01

The new synchrotron light source ALBA is currently starting regular operation. Up to 6 beamlines are using light produced by Insertion Devices. There are up to four types of IDs: 2 Apple-II undulators (EU62 and EU71) operating at low energies, one conventional wiggler (MPW80) operating in the range of 2 - 20 keV, two in-vacuum undulators (IVU21) operating in the range 5 - 30 keV and a superconducting wiggler (SCW30) operating in the range of (up to) 40 keV. The main IDs characteristics, their influence on the beam dynamics and a first characterization of their light will be presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, T.; Zimoch, D.

The operation of an APPLE II based undulator beamline with all its polarization states (linear horizontal and vertical, circular and elliptical, and continous variation of the linear vector) requires an effective description allowing an automated calculation of gap and shift parameter as function of energy and operation mode. The extension of the linear polarization range from 0 to 180 deg. requires 4 shiftable magnet arrrays, permitting use of the APU (adjustable phase undulator) concept. Studies for a pure fixed gap APPLE II for the SLS revealed surprising symmetries between circular and linear polarization modes allowing for simplified operation. A semi-analyticalmore » model covering all types of APPLE II and its implementation will be presented.« less

About APPLE II Operation

NASA Astrophysics Data System (ADS)

Schmidt, T.; Zimoch, D.

2007-01-01

The operation of an APPLE II based undulator beamline with all its polarization states (linear horizontal and vertical, circular and elliptical, and continous variation of the linear vector) requires an effective description allowing an automated calculation of gap and shift parameter as function of energy and operation mode. The extension of the linear polarization range from 0 to 180° requires 4 shiftable magnet arrrays, permitting use of the APU (adjustable phase undulator) concept. Studies for a pure fixed gap APPLE II for the SLS revealed surprising symmetries between circular and linear polarization modes allowing for simplified operation. A semi-analytical model covering all types of APPLE II and its implementation will be presented.

INITIAL GAIN MEASUREMENTS OF A 800 NM SASE FEL, VISA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

FRIGOLA,P.; MUROKH,A.; ET AL

2000-08-13

The VISA (Visible to Infrared SASE Amplifier) FEL is designed to obtain high gain at a radiation wavelength of 800nm. The FEL uses the high brightness electron beam of the Accelerator Test Facility (ATF), with energy of 72MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6mm and a period of 1.8cm. To obtain large gain the beam and undulator axis have to be aligned to better than 50{micro}m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations.

An X-Ray Source for Lithography Based on a Quasi-Optical Maser Undulator

DTIC Science & Technology

1989-05-09

an electron, c is the speed of light in vacuo, B is the peak magnetic induction and X is the period of the planar undulator or wiggler, the wavelength...relativistic motion is given 11 p = Le’ Y 6 [2 - X )2] (4) where = v/c is the particle velocity normalized to the speAd of light , and § /c, where v = -v is...k0 z + Wt),) (7) where E is the amplitude of the electric field, w is the radian frequency A and k a (0,0,k ) is the wave- vector . ez is a unit vector

GEOS 3 data processing for the recovery of geoid undulations and gravity anomalies

NASA Technical Reports Server (NTRS)

Rapp, R. H.

1979-01-01

The paper discusses the analysis of GEOS 3 altimeter data for the determination of geoid heights and point and mean gravity anomalies. Methods are presented for determining the mean anomalies and mean undulations from the GEOS 3 altimeter data available by the end of September 1977 without having a complete set of precise orbits. The editing of the data is extensive to remove questionable data, although no filtering of the data is carried out. An adjustment process is carried out to eliminate orbit error and altimeter bias. Representative point anomaly values are computed to investigate anomaly behavior across the Bonin Trench and over the Patton seamounts.

Observations of z-dependent microbunching harmonic intensities using COTR in a SASE FEL.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumpkin, A. H.; Biedron, S. G.; Dejus, R. J.

The nonlinear generation of harmonics in a self-amplified spontaneous emission (SASE) free-electron laser (FEL) continues to be of interest. Complementary to such studies is the search for information on the electron beam microbunching harmonic components, which are revealed by coherent optical transition radiation (COTR) experiments. An initial z-dependent set of data has been obtained with the fundamental at 530 nm and the second harmonic at 265 nm. The latter data were collected after every other undulator in a nine-undulator string. These results are compared to estimates based on GINGER and an analytical model for nonlinear harmonic generation.

Assessing the quality of GEOID12B model through field surveys

NASA Astrophysics Data System (ADS)

Elaksher, Ahmed; Kamtchang, Franck; Wegmann, Christian; Guerrero, Adalberto

2018-01-01

Elevation differences have been determined through conventional ground surveying techniques for over a century. Since the mid-80s GPS, GLONASS and other satellite systems have modernized the means by which elevation differences are observed. In this article, we assessed the quality of GEIOD12B through long-occupation GNSS static surveys. A set of NGS benchmarks was occupied for at least one hour using dual-frequency GNSS receivers. Collected measurements were processed using a single CORS station at most 24 kilometers from the benchmarks. Geoid undulation values were driven by subtracting measured ellipsoidal heights from the orthometric heights posted on the NGS website. To assess the quality of GEOID12B, we compared our computed vertical shifts at the benchmarks with those estimated from GEOID12B published by NGS. In addition, Kriging model was used to interpolate local maps for the geoid undulations from the benchmark heights. The maps were compared with corresponding parts of GEOID12B. No biases were detected in the results and only shifts due to random errors were found. Discrepancies in the range of ten centimetres were noticed between our geoid undulation and the values available from NGS.

Numerical study of laminar, standing hydraulic jumps in a planar geometry.

PubMed

Dasgupta, Ratul; Tomar, Gaurav; Govindarajan, Rama

2015-05-01

We solve the two-dimensional, planar Navier-Stokes equations to simulate a laminar, standing hydraulic jump using a Volume-of-Fluid method. The geometry downstream of the jump has been designed to be similar to experimental conditions by including a pit at the edge of the platform over which liquid film flows. We obtain jumps with and without separation. Increasing the inlet Froude number pushes the jump downstream and makes the slope of the jump weaker, consistent with experimental observations of circular jumps, and decreasing the Reynolds number brings the jump upstream while making it steeper. We study the effect of the length of the domain and that of a downstream obstacle on the structure and location of the jump. The transient flow which leads to a final steady jump is described for the first time to our knowledge. In the moderate Reynolds number regime, we obtain steady undular jumps with a separated bubble underneath the first few undulations. Interestingly, surface tension leads to shortening of wavelength of these undulations. We show that the undulations can be explained using the inviscid theory of Benjamin and Lighthill (Proc. R. Soc. London, Ser. A, 1954). We hope this new finding will motivate experimental verification.

Optimization of the LCLS X-Ray FEL Output Performance in the Presence of Strong Undulator Wakefields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reiche, S.; /UCLA; Bane, K.L.F.

The Linac Coherent Light Source (LCLS) Free-Electron Laser will operate in the wavelength range of 1.5 to 15 Angstroms. Energy loss due to wakefields within the long undulator can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive component is the most critical and depends upon the chamber material (e.g. Cu) and its radius. To study the expected performance in the presence of these wakefields, we make a series of start-to-end simulations with tracking codes PARMELAmore » and ELEGANT and time-dependent FEL simulation codes Genesis 1.3 and Ginger. We discuss the impact of the wakefield on output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation obtained with a slight z dependent taper in the undulator field. We compare these results to those obtained by decreasing the bunch charge or increasing the vacuum chamber radius. We also compare our results to those predicted in concurrent analytical work.« less

Preliminary estimates of Gulf Stream characteristics from TOPEX data and a precise gravimetric geoid

NASA Technical Reports Server (NTRS)

Rapp, Richard H.; Smith, Dru A.

1994-01-01

TOPEX sea surface height data has been used, with a gravimetric geoid, to calculate sea surface topography across the Gulf Stream. This topography was initially computed for nine tracks on cycles 21 to 29. Due to inaccurate geoid undulations on one track, results for eight tracks are reported. The sea surface topography estimates were used to calculate parameters that describe Gulf Stream characteristics from two models of the Gulf Stream. One model was based on a Gaussian representation of the velocity while the other was a hyperbolic representation of velocity or the sea surface topography. The parameters of the Gaussian velocity model fit were a width parameter, a maximum velocity value, and the location of the maximum velocity. The parameters of the hyperbolic sea surface topography model were the width, the height jump, position, and sea surface topography at the center of the stream. Both models were used for the eight tracks and nine cycles studied. Comparisons were made between the width parameters, the maximum velocities, and the height jumps. Some of the parameter estimates were found to be highly (0.9) correlated when the hyperbolic sea surface topography fit was carried out, but such correlations were reduced for either the Gaussian velocity fits or the hyperbolic velocity model fit. A comparison of the parameters derived from 1-year TOPEX data showed good agreement with values derived by Kelly (1991) using 2.5 years of Geosat data near 38 deg N, 66 deg W longitude. Accuracy of the geoid undulations used in the calculations was of order of +/- 16 cm with the accuracy of a geoid undulation difference equal to +/- 15 cm over a 100-km line in areas with good terrestrial data coverage. This paper demonstrates that our knowledge or geoid undulations and undulation differences, in a portion of the Gulf Stream region, is sufficiently accurate to determine characteristics of the jet when used with TOPEX altimeter data. The method used here has not been shown to be more accurate than methods that average altimeter data to form a reference surface used in analysis to obtain the Gulf Stream characteristics. However, the results show the geoid approach may be used in areas where lack of current meandering reduces the accuracy of the average surface procedure.

Student Support for Research in Hierarchical Control and Trajectory Planning

NASA Technical Reports Server (NTRS)

Martin, Clyde F.

1999-01-01

Generally, classical polynomial splines tend to exhibit unwanted undulations. In this work, we discuss a technique, based on control principles, for eliminating these undulations and increasing the smoothness properties of the spline interpolants. We give a generalization of the classical polynomial splines and show that this generalization is, in fact, a family of splines that covers the broad spectrum of polynomial, trigonometric and exponential splines. A particular element in this family is determined by the appropriate control data. It is shown that this technique is easy to implement. Several numerical and curve-fitting examples are given to illustrate the advantages of this technique over the classical approach. Finally, we discuss the convergence properties of the interpolant.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Q. G.; Chen, N.; Zhang, M.

Five IDs will be built for the Shanghai Synchrotron Radiation Facility (SSRF). Two identical mini-gap undulators with the period length 25mm and the minimum gap 6mm will use the in-vacuum technology and can operate in tapered mode. Two wigglers with the period lengths 7.9cm and 14cm and the same minimum gap 14mm will produce the peak fields of 1.2T and 1.94T. A variable polarization undulator of the APPLE-II type with 4.2m long and the period length 10cm can provide linearly, circularly and elliptically polarized radiation in a wide spectral range. This paper describes the magnet designs and the mechanical structuremore » designs of these IDs.« less

Fabrication and assembly of a superconducting undulator for the advanced photon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasse, Quentin; Fuerst, J. D.; Ivanyushenkov, Y.

2014-01-29

A prototype superconducting undulator magnet (SCU0) has been built at the Advanced Photon Source (APS) of Argonne National Laboratory (ANL) and has successfully completed both cryogenic performance and magnetic measurement test programs. The SCU0 closed loop, zero-boil-off cryogenic system incorporates high temperature superconducting (HTS) current leads, cryocoolers, a LHe reservoir supplying dual magnetic cores, and an integrated cooled beam chamber. This system presented numerous challenges in the design, fabrication, and assembly of the device. Aspects of this R and D relating to both the cryogenic and overall assembly of the device are presented here. The SCU0 magnet has been installedmore » in the APS storage ring.« less

Linac coherent light source (LCLS) undulator RF BPM system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lill, R.; Waldschmidt, G.; Morrison, L.

2006-01-01

The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL) when it becomes operational in 2009. The LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high-resolution X-band cavity BPM system described in this paper. The BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication, and high resolution make it an ideal choice for LCLS beam position detection. We will discuss the system specifications, design, andmore » prototype test results.« less

Linac Coherent Light Source Undulator RF BPM System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lill, R.M.; Morrison, L.H.; Waldschmidt, G.J.

2007-04-17

The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL) when it becomes operational in 2009. The LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high-resolution X-band cavity BPM system described in this paper. The BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication, and high resolution make it an ideal choice for LCLS beam position detection. We will discuss the system specifications, design, andmore » prototype test results.« less

Low-frequency quadrupole impedance of undulators and wigglers

DOE PAGES

Blednykh, A.; Bassi, G.; Hidaka, Y.; ...

2016-10-25

An analytical expression of the low-frequency quadrupole impedance for undulators and wigglers is derived and benchmarked against beam-based impedance measurements done at the 3 GeV NSLS-II storage ring. The adopted theoretical model, valid for an arbitrary number of electromagnetic layers with parallel geometry, allows to calculate the quadrupole impedance for arbitrary values of the magnetic permeability μ r. Here, in the comparison of the analytical results with the measurements for variable magnet gaps, two limit cases of the permeability have been studied: the case of perfect magnets (μ r → ∞), and the case in which the magnets are fullymore » saturated (μ r = 1).« less

Progress on the development of the next generation x-ray beam position monitors at the advanced photon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S. H., E-mail: shlee@aps.anl.gov; Yang, B. X., E-mail: bxyang@aps.anl.gov; Decker, G., E-mail: decker@aps.anl.gov

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source (APS). The next generation XBPMs for high heat load front ends (HHL FEs) have been designed to meet these requirements by utilizing Cu K-edge x-ray fluorescence (XRF) from a pair of copper absorbers and have been installed at the front ends (FEs) of the APS. Commissioning data showed a significant performance improvement over the existing photoemission-based XBPMs. While a similar design concept can be applied for the canted undulator front ends, where two undulator beams are separatedmore » by 1.0-mrad, the lower beam power (< 10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from the diamond blades placed edge-on to the x-ray beam. A prototype of the Compton scattering XBPM system was installed at 24-ID-A in May 2015. In this report, the design and test results for XRF-based XBPM and Compton scattering based XBPM are presented. Ongoing research related to the development of the next generation XBPMs on thermal contact resistance of a joint between two solid bodies is also discussed.« less

The Subglacial Drainage Patterns of Devon Island, Canada

NASA Astrophysics Data System (ADS)

Grau Galofre, A.; Jellinek, M.; Osinski, G. R.

2016-12-01

Meltwater drainage patterns incised underneath ice masses can appear strikingly similar to fluvially dissected landscapes. We introduce a landscape evolution model to describe the longitudinal profiles of subglacial meltwater channels (tunnel valleys).We propose a way to identify them from topography data and imagery on the basis of the vertical scale of undulations compared to the total elevation gain. We test the model with field data from tunnel valleys exposed in Devon Island, NU, Canada. We use field measurements of longitudinal profiles, photogrammetry and 3D LIDAR to establish a quantitative comparison of tunnel valleys and fluvial channels. Tunnel valleys are oriented parallel to former ice flow lines and are characterized by undulating longitudinal profiles. We use these features to identify quantitatively tunnel valleys in central Devon Island (figure 1). We ground truth our observations with imagery of tunnel valleys appearing at the edges of the actively retreating ice cap. Longitudinal profiles show undulations with amplitudes up to 14m over a total elevation gain of 20m and with wavelengths comparable to the channel width. These "overdeepenings" are not observed in any fluvial channels in the area and are consistent with expectations of flow driven by variations in ice thickness. Our identification scheme rigorously distinguishes fluvial and subglacial dissected landscapes.

Comparison of undulation difference accuracies using gravity anomalies and gravity disturbances. [for ocean geoid

NASA Technical Reports Server (NTRS)

Jekeli, C.

1980-01-01

Errors in the outer zone contribution to oceanic undulation differences computed from a finite set of potential coefficients based on satellite measurements of gravity anomalies and gravity disturbances are analyzed. Equations are derived for the truncation errors resulting from the lack of high-degree coefficients and the commission errors arising from errors in the available lower-degree coefficients, and it is assumed that the inner zone (spherical cap) is sufficiently covered by surface gravity measurements in conjunction with altimetry or by gravity anomaly data. Numerical computations of error for various observational conditions reveal undulation difference errors ranging from 13 to 15 cm and from 6 to 36 cm in the cases of gravity anomaly and gravity disturbance data, respectively for a cap radius of 10 deg and mean anomalies accurate to 10 mgal, with a reduction of errors in both cases to less than 10 cm as mean anomaly accuracy is increased to 1 mgal. In the absence of a spherical cap, both cases yield error estimates of 68 cm for an accuracy of 1 mgal and between 93 and 160 cm for the lesser accuracy, which can be reduced to about 110 cm by the introduction of a perfect 30-deg reference field.

Accuracy of the determination of mean anomalies and mean geoid undulations from a satellite gravity field mapping mission

NASA Technical Reports Server (NTRS)

Jekeli, C.; Rapp, R. H.

1980-01-01

Improved knowledge of the Earth's gravity field was obtained from new and improved satellite measurements such as satellite to satellite tracking and gradiometry. This improvement was examined by estimating the accuracy of the determination of mean anomalies and mean undulations in various size blocks based on an assumed mission. In this report the accuracy is considered through a commission error due to measurement noise propagation and a truncation error due to unobservable higher degree terms in the geopotential. To do this the spectrum of the measurement was related to the spectrum of the disturbing potential of the Earth's gravity field. Equations were derived for a low-low (radial or horizontal separation) mission and a gradiometer mission. For a low-low mission of six month's duration, at an altitude of 160 km, with a data noise of plus or minus 1 micrometers sec for a four second integration time, we would expect to determine 1 deg x 1 deg mean anomalies to an accuracy of plus or minus 2.3 mgals and 1 deg x 1 deg mean geoid undulations to plus or minus 4.3 cm. A very fast Fortran program is available to study various mission configurations and block sizes.

Undulating fins produce off-axis thrust and flow structures.

PubMed

Neveln, Izaak D; Bale, Rahul; Bhalla, Amneet Pal Singh; Curet, Oscar M; Patankar, Neelesh A; MacIver, Malcolm A

2014-01-15

While wake structures of many forms of swimming and flying are well characterized, the wake generated by a freely swimming undulating fin has not yet been analyzed. These elongated fins allow fish to achieve enhanced agility exemplified by the forward, backward and vertical swimming capabilities of knifefish, and also have potential applications in the design of more maneuverable underwater vehicles. We present the flow structure of an undulating robotic fin model using particle image velocimetry to measure fluid velocity fields in the wake. We supplement the experimental robotic work with high-fidelity computational fluid dynamics, simulating the hydrodynamics of both a virtual fish, whose fin kinematics and fin plus body morphology are measured from a freely swimming knifefish, and a virtual rendering of our robot. Our results indicate that a series of linked vortex tubes is shed off the long edge of the fin as the undulatory wave travels lengthwise along the fin. A jet at an oblique angle to the fin is associated with the successive vortex tubes, propelling the fish forward. The vortex structure bears similarity to the linked vortex ring structure trailing the oscillating caudal fin of a carangiform swimmer, though the vortex rings are distorted because of the undulatory kinematics of the elongated fin.

Maneuverability and chemotaxis of Caenorhabditis elegans in three-dimensional environments

NASA Astrophysics Data System (ADS)

Blawzdziewicz, Jerzy; Bilbao, Alejandro; Patel, Amar; Vanapalli, Siva

2015-11-01

Locomotion of the nematode C. elegans in water and complex fluids has recently been investigated to gain insight into neuromuscular control of locomotion and to shed light on nematode evolutionary adaptation to environments with varying mechanical properties. Previous studies focused mainly on locomotion efficiency and on adaptation of the nematode gait to the surrounding medium. Much less attention has been devoted to nematode maneuverability, in spite of its crucial role in the survival of the animal. Recently we have provided a quantitative analysis of turning maneuvers of crawling and swimming nematodes on flat surfaces and in 2D fluid layers. Based on this work, we follow with the first full 3D description of how C. elegans moves in complex 3D environments. We show that by superposing body twist and 2D undulations, a burrowing or swimming nematode can rotate the undulation plane and change the direction of motion within that plane by varying undulation-wave parameters. A combination of these corkscrew maneuvers and 2D turns allows the nematode to explore 3D space. We conclude by analyzing 3D chemotaxis of nematodes burrowing in gel and swimming in water, which demonstrates an important application of our maneuverability model. This work was supported by NSF grant CBET-1059745.

Modelling local GPS/levelling geoid undulations using artificial neural networks

NASA Astrophysics Data System (ADS)

Kavzoglu, T.; Saka, M. H.

2005-04-01

The use of GPS for establishing height control in an area where levelling data are available can involve the so-called GPS/levelling technique. Modelling of the GPS/levelling geoid undulations has usually been carried out using polynomial surface fitting, least-squares collocation (LSC) and finite-element methods. Artificial neural networks (ANNs) have recently been used for many investigations, and proven to be effective in solving complex problems represented by noisy and missing data. In this study, a feed-forward ANN structure, learning the characteristics of the training data through the back-propagation algorithm, is employed to model the local GPS/levelling geoid surface. The GPS/levelling geoid undulations for Istanbul, Turkey, were estimated from GPS and precise levelling measurements obtained during a field study in the period 1998-99. The results are compared to those produced by two well-known conventional methods, namely polynomial fitting and LSC, in terms of root mean square error (RMSE) that ranged from 3.97 to 5.73 cm. The results show that ANNs can produce results that are comparable to polynomial fitting and LSC. The main advantage of the ANN-based surfaces seems to be the low deviations from the GPS/levelling data surface, which is particularly important for distorted levelling networks.

Estimation of the ocean geoid near the Blake Escarpment using GEOS-3 satellite altimetry

NASA Technical Reports Server (NTRS)

Brammer, R. F.

1979-01-01

The accuracy with which the local ocean geoid structure could be determined using satellite altimetry data was investigated. The undulation and along-track component of the vertical deflection for selected passes of GEOS-3 near the Blake Escarpment were estimated and compared with independent analogous estimates based on U. S. Navy surface gravimetric survey data. The results of these comparisons show agreement in the geoid undulation values generally to within one or two meters. The nature of the discrepancy in the undulation values was primarily that of a bias error believed to be due essentially to radial orbit uncertainties. The agreement between the vertical deflection estimates was not significantly affected by orbit uncertainties over the track lengths considered in this study (100 - 1500 km), and the comparisons show typical rms differences of between one and two arc secs. In addition, the capability of the altimeter to resolve short wavelength features of the geoid was determined. This analysis involved spectrum and cross spectrum analysis of sets of closely spaced parallel subtracks to determine statistically significant short wavelength geoid resolution capability. The results of this analysis show that resolution can be achieved down to wavelengths as short as 30 km - 80 km depending on regional geoid variations.

Geoid undulations and gravity anomalies over the Aral Sea, the Black Sea and the Caspian Sea from a combined GEOS-3/SEASAT/GEOSAT altimeter data set

NASA Technical Reports Server (NTRS)

Au, Andrew Y.; Brown, Richard D.; Welker, Jean E.

1991-01-01

Satellite-based altimetric data taken by GOES-3, SEASAT, and GEOSAT over the Aral Sea, the Black Sea, and the Caspian Sea are analyzed and a least squares collocation technique is used to predict the geoid undulations on a 0.25x0.25 deg. grid and to transform these geoid undulations to free air gravity anomalies. Rapp's 180x180 geopotential model is used as the reference surface for the collocation procedure. The result of geoid to gravity transformation is, however, sensitive to the information content of the reference geopotential model used. For example, considerable detailed surface gravity data were incorporated into the reference model over the Black Sea, resulting in a reference model with significant information content at short wavelengths. Thus, estimation of short wavelength gravity anomalies from gridded geoid heights is generally reliable over regions such as the Black Sea, using the conventional collocation technique with local empirical covariance functions. Over regions such as the Caspian Sea, where detailed surface data are generally not incorporated into the reference model, unconventional techniques are needed to obtain reliable gravity anomalies. Based on the predicted gravity anomalies over these inland seas, speculative tectonic structures are identified and geophysical processes are inferred.

LCLS X-Ray FEL Output Performance in the Presence of Highly Time-Dependent Undulator Wakefields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fawley, W.M.; /LBL, Berkeley; Bane, K.L.F.

Energy loss due to wakefields within a long undulator, if not compensated by an appropriate tapering of the magnetic field strength, can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive-wall component is the most critical and depends upon the chamber material (e.g., Cu) and its radius. Of recent interest[1] is the so-called ''AC'' component of the resistive-wall wake which can lead to strong variations on very short timescales (e.g., {approx} 20 fs). To study themore » expected performance of the LCLS in the presence of these wakefields, we have made an extensive series of start-to-end SASE simulations with tracking codes PARMELA and ELEGANT, and time-dependent FEL simulation codes GENESIS1.3 and GINGER. We discuss the impact of the wakefield losses upon output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation of the time-dependent wake losses obtained with a slight z-dependent taper in the undulator field. We compare the taper results to those predicted analytically[2].« less

STUDIES OF A FREE ELECTRON LASER DRIVEN BY A LASER-PLASMA ACCELERATOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montgomery, A.; Schroeder, C.; Fawley, W.

A free electron laser (FEL) uses an undulator, a set of alternating magnets producing a periodic magnetic fi eld, to stimulate emission of coherent radiation from a relativistic electron beam. The Lasers, Optical Accelerator Systems Integrated Studies (LOASIS) group at Lawrence Berkeley National Laboratory (LBNL) will use an innovative laserplasma wakefi eld accelerator to produce an electron beam to drive a proposed FEL. In order to optimize the FEL performance, the dependence on electron beam and undulator parameters must be understood. Numerical modeling of the FEL using the simulation code GINGER predicts the experimental results for given input parameters. Amongmore » the parameters studied were electron beam energy spread, emittance, and mismatch with the undulator focusing. Vacuum-chamber wakefi elds were also simulated to study their effect on FEL performance. Energy spread was found to be the most infl uential factor, with output FEL radiation power sharply decreasing for relative energy spreads greater than 0.33%. Vacuum chamber wakefi elds and beam mismatch had little effect on the simulated LOASIS FEL at the currents considered. This study concludes that continued improvement of the laser-plasma wakefi eld accelerator electron beam will allow the LOASIS FEL to operate in an optimal regime, producing high-quality XUV and x-ray pulses.« less

Harmonic cascade FEL designs for LUX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penn, G.; Reinsch, M.; Wurtele, J.

LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1more » keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.« less

LCLS X-Ray FEL Output Performance in the Presence of HighlyTime-Dependent Undulator Wakefields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bane, Karl L.F.; Emma, Paul; Huang, Heinz-Dieter Nuhn

Energy loss due to wakefields within a long undulator, if not compensated by an appropriate tapering of the magnetic field strength, can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive-wall component is the most critical and depends upon the chamber material (e.g., Cu) and its radius. Of recent interest[1] is the so-called ''AC'' component of the resistive-wall wake which can lead to strong variations on very short timescales (e.g., {approx} 20 0fs). To study themore » expected performance of the LCLS in the presence of these wakefields, we have made an extensive series of start-to-end SASE simulations with tracking codes PARMELA and ELEGANT, and time-dependent FEL simulation codes GENESIS1.3 and GINGER. We discuss the impact of the wakefield losses upon output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation of the time-dependent wake losses obtained with a slight z-dependent taper in the undulator field. We compare the taper results to those predicted analytically[2].« less

Effect of Angle on Flow-Induced Vibrations of Pinniped Vibrissae

PubMed Central

Murphy, Christin T.; Eberhardt, William C.; Calhoun, Benton H.; Mann, Kenneth A.; Mann, David A.

2013-01-01

Two types of vibrissal surface structures, undulated and smooth, exist among pinnipeds. Most Phocidae have vibrissae with undulated surfaces, while Otariidae, Odobenidae, and a few phocid species possess vibrissae with smooth surfaces. Variations in cross-sectional profile and orientation of the vibrissae also exist between pinniped species. These factors may influence the way that the vibrissae behave when exposed to water flow. This study investigated the effect that vibrissal surface structure and orientation have on flow-induced vibrations of pinniped vibrissae. Laser vibrometry was used to record vibrations along the whisker shaft from the undulated vibrissae of harbor seals (Phoca vitulina) and northern elephant seals (Mirounga angustirostris) and the smooth vibrissae of California sea lions (Zalophus californianus). Vibrations along the whisker shaft were measured in a flume tank, at three orientations (0°, 45°, 90°) to the water flow. The results show that vibration frequency and velocity ranges were similar for both undulated and smooth vibrissae. Angle of orientation, rather than surface structure, had the greatest effect on flow-induced vibrations. Vibration velocity was up to 60 times higher when the wide, flat aspect of the whisker faced into the flow (90°), compared to when the thin edge faced into the flow (0°). Vibration frequency was also dependent on angle of orientation. Peak frequencies were measured up to 270 Hz and were highest at the 0° orientation for all whiskers. Furthermore, CT scanning was used to quantify the three-dimensional structure of pinniped vibrissae that may influence flow interactions. The CT data provide evidence that all vibrissae are flattened in cross-section to some extent and that differences exist in the orientation of this profile with respect to the major curvature of the hair shaft. These data support the hypothesis that a compressed cross-sectional profile may play a key role in reducing self-noise of the vibrissae. PMID:23922834

Mini-beam collimator enables microcrystallography experiments on standard beamlines

PubMed Central

Fischetti, Robert F.; Xu, Shenglan; Yoder, Derek W.; Becker, Michael; Nagarajan, Venugopalan; Sanishvili, Ruslan; Hilgart, Mark C.; Stepanov, Sergey; Makarov, Oleg; Smith, Janet L.

2009-01-01

The high-brilliance X-ray beams from undulator sources at third-generation synchrotron facilities are excellent tools for solving crystal structures of important and challenging biological macromolecules and complexes. However, many of the most important structural targets yield crystals that are too small or too inhomogeneous for a ‘standard’ beam from an undulator source, ∼25–50 µm (FWHM) in the vertical and 50–100 µm in the horizontal direction. Although many synchrotron facilities have microfocus beamlines for other applications, this capability for macromolecular crystallography was pioneered at ID-13 of the ESRF. The National Institute of General Medical Sciences and National Cancer Institute Collaborative Access Team (GM/CA-CAT) dual canted undulator beamlines at the APS deliver high-intensity focused beams with a minimum focal size of 20 µm × 65 µm at the sample position. To meet growing user demand for beams to study samples of 10 µm or less, a ‘mini-beam’ apparatus was developed that conditions the focused beam to either 5 µm or 10 µm (FWHM) diameter with high intensity. The mini-beam has a symmetric Gaussian shape in both the horizontal and vertical directions, and reduces the vertical divergence of the focused beam by 25%. Significant reduction in background was achieved by implementation of both forward- and back-scatter guards. A unique triple-collimator apparatus, which has been in routine use on both undulator beamlines since February 2008, allows users to rapidly interchange the focused beam and conditioned mini-beams of two sizes with a single mouse click. The device and the beam are stable over many hours of routine operation. The rapid-exchange capability has greatly facilitated sample screening and resulted in several structures that could not have been obtained with the larger focused beam. PMID:19240333

Multicascade X-Ray Free-Electron Laser with Harmonic Multiplier and Two-Frequency Undulator

NASA Astrophysics Data System (ADS)

Zhukovsky, K. V.

2018-06-01

The feasibility of generation of powerful x-ray radiation by a cascade free-electron laser (FEL) with amplification of higher harmonics using a two-frequency undulator is studied. To analyze the FEL operation, a complex phenomenological single-pass FEL model is developed and used. It describes linear and nonlinear generation of harmonics in the FEL with seed laser that takes into account initial electron beam noise and describes all main losses of each harmonic in each FEL cascade. The model is also calibrated against and approved by the experimental FEL data and available results of three-dimensional numerical simulation. The electron beam in the undulator is assumed to be matched and focused, and the dynamics of power in the singlepass FEL with cascade harmonic multipliers is investigated to obtain x-ray laser radiation in the FEL having the shortest length, beam energy, and frequency of the seed laser as low as possible. In this context, the advantages of the two-frequency undulator used for generation of harmonics are demonstrated. The evolution of harmonics in a multicascade FEL with multiplication of harmonics is investigated. The operation of the cascade FEL at the wavelength λ = 1.14 nm, generating 30 MW already on 38 m with the seed laser operating at a wavelength of 11.43 nm corresponding to the maximal reflectivity of the multilayered mirror MoRu/Be coating is investigated. In addition, the operation of the multicascade FEL with accessible seed UVlaser operating at a wavelength of 157 nm (F2 excimer UV-laser) and electron beam with energy of 0.5 GeV is investigated. X-ray radiation simulated in it at the wavelength λ 3.9 nm reaches power of 50 MW already at 27 m, which is by two orders of magnitude shorter than 3.4 km of the x-ray FEL recently put into operation in Europe.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Sen; Luo, Sheng-Nian

Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10–100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are exploredviaGaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamentalmore » harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.« less

Cryogenic performance of a cryocooler-cooled superconducting undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fuerst, J. D.; Doose, C.; Hasse, Q.

2014-01-29

A cryocooler-cooled superconducting undulator has been installed and operated with beam at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The device consists of a dual-core 42-pole magnet structure that is cooled to 4.2 K with a system of four cryocoolers operating in a zero-boil-off configuration. This effort represents the culmination of a development program to establish concept feasibility and evaluate cryostat design and cryocooler-based refrigeration. Cryostat performance is described including cool-down/warm-up, steady-state operation, cooling margin, and the impact of beam during operation in the APS storage ring. Plans for future devices with longer magnets, which will incorporatemore » lessons learned from the development program, are also discussed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strelnikov, N.; Vasserman, I.; Xu, J.

As part of the R&D program of the LCLS-II project, a novel 3.4-meter-long undulator prototype with horizontal magnetic field and dynamic force compensation has recently been developed at the Advanced Photon Source (APS). Some previous steps in this development were the shorter 0.8-meter-long and 2.8-meter-long prototypes. Extensive mechanical and magnetic testing was carried out for each prototype, and each prototype was magnetically tuned using magnetic shims. Furthermore, the resulting performance of the 3.4-meter-long undulator prototype meets all requirements for the LCLS-II insertion device, including limits on the field integrals, phase errors, higher-order magnetic moments, and electron-beam trajectory for all operationalmore » gaps, as well as the reproducibility and accuracy of the gap settings.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flechsig, U.; Nolting, F.; Fraile Rodriguez, A.

The Surface/Interface: Microscopy beamline of the Swiss Light Source started operation in 2001. In 2007 the beamline has been significantly upgraded with a second refocusing section and a blazed grating optimized for high photon flux. Two Apple II type undulators with a plane grating monochromator using the collimated light scheme deliver photons with an energy from 90eV to about 2keV with variable polarization for the photoemission electron microscope (PEEM) as the primary user station. We measured a focus of (45x60) {mu}m({nu}xh) and a photon flux > 10{sup 12} photon/s for all gratings. Polarization switching within a few seconds is realizedmore » with the small bandpass of the monochromator and a slight detuning of the undulator.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krempasky, J.; Flechsig, U.; Korhonen, T.

Synchronous monochromator and insertion device energy scans were implemented at the Surfaces/Interfaces:Microscopy (SIM) beamline in order to provide the users fast X-ray magnetic dichroism studies (XMCD). A simple software control scheme is proposed based on a fast monochromator run-time energy readback which quickly updates the insertion device requested energy during an on-the-fly X-ray absorption scan (XAS). In this scheme the Plain Grating Monochromator (PGM) motion control, being much slower compared with the insertion device (APPLE-II type undulator), acts as a 'master' controlling the undulator 'slave' energy position. This master-slave software implementation exploits EPICS distributed device control over computer network andmore » allows for a quasi-synchronous motion control combined with data acquisition needed for the XAS or XMCD experiment.« less

Advanced photoelectric effect experiment beamline at Elettra: A surface science laboratory coupled with Synchrotron Radiation.

PubMed

Panaccione, G; Vobornik, I; Fujii, J; Krizmancic, D; Annese, E; Giovanelli, L; Maccherozzi, F; Salvador, F; De Luisa, A; Benedetti, D; Gruden, A; Bertoch, P; Polack, F; Cocco, D; Sostero, G; Diviacco, B; Hochstrasser, M; Maier, U; Pescia, D; Back, C H; Greber, T; Osterwalder, J; Galaktionov, M; Sancrotti, M; Rossi, G

2009-04-01

We report the main characteristics of the advanced photoelectric effect experiments beamline, operational at Elettra storage ring, featuring a fully independent double branch scheme obtained by the use of chicane undulators and able to keep polarization control in both linear and circular mode. The paper describes the novel technical solutions adopted, namely, (a) the design of a quasiperiodic undulator resulting in optimized suppression of higher harmonics over a large photon energy range (10-100 eV), (b) the thermal stability of optics under high heat load via cryocoolers, and (c) the end station interconnected setup allowing full access to off-beam and on-beam facilities and, at the same time, the integration of users' specialized sample growth chambers or modules.

Subradiant spontaneous undulator emission through collective suppression of shot noise

DOE PAGES

Ratner, D.; Hemsing, E.; Gover, A.; ...

2015-05-01

The phenomenon of Dicke’s subradiance, in which the collective properties of a system suppress radiation, has received broad interest in atomic physics. Recent theoretical papers in the field of relativistic electron beams have proposed schemes to achieve subradiance through suppression of shot noise current fluctuations. The resulting “quiet” beam generates less spontaneous radiation than emitted even by a shot noise beam when oscillating in an undulator. Quiet beams could have diverse accelerator applications, including lowering power requirements for seeded free-electron lasers and improving efficiency of hadron cooling. In this paper we present experimental observation of a strong reduction in undulatormore » radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.« less

Detailed gravity anomalies from GEOS-3 satellite altimetry data

NASA Technical Reports Server (NTRS)

Gopalapillai, G. S.; Mourad, A. G.

1978-01-01

A technique for deriving mean gravity anomalies from dense altimetry data was developed. A combination of both deterministic and statistical techniques was used. The basic mathematical model was based on the Stokes' equation which describes the analytical relationship between mean gravity anomalies and geoid undulations at a point; this undulation is a linear function of the altimetry data at that point. The overdetermined problem resulting from the excessive altimetry data available was solved using Least-Squares principles. These principles enable the simultaneous estimation of the associated standard deviations reflecting the internal consistency based on the accuracy estimates provided for the altimetry data as well as for the terrestrial anomaly data. Several test computations were made of the anomalies and their accuracy estimates using GOES-3 data.

Installation of Multiple Application X-ray Imaging Undulator Microscope (MAXIMUM) at ALS: Final report, 8/15/95-8/15/96

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1996-12-31

MAXIMUM is short for Multiple Application X-ray IMaging Undulator Microscope, a project started in 1988 by our group at the Synchrotron Radiation Center of the University of Wisconsin-Madison. It is a scanning x-ray photoemission microscope that uses a multilayer-coated Schwarzschild objective as the focusing element. It was designed primarily for materials science studies of lateral variations in surface chemistry. Suitable problems include: lateral inhomogeneities in Schottky barrier formation, heterojunction formation, patterned samples and devices, insulating samples. Any system which has interesting properties that are not uniform as a function of spatial dimension can potentially be studied with MAXIMUM. 6 figs.,more » 3 tabs.« less

Analyzing the Broken Ridge area of the Indian Ocean using magnetic and gravity anomaly maps and geoid undulation and bathymetry data

NASA Technical Reports Server (NTRS)

Lazarewicz, A. R.; Sailor, R. V. (Principal Investigator)

1982-01-01

A higher resolution anomaly map of the Broken Ridge area (2 degree dipole spacing) was produced and reduced to the pole using quiet time data for this area. The map was compared with equally scaled maps of gravity anomaly, geoid undulation, and bathymetry. The ESMAP results were compared with a NASA MAGSAT map derived by averaging data in two-degree bins. A survey simulation was developed to model the accuracy of MAGSAT anomaly maps as a function of satellite altitude, instrument noise level, external noise model, and crustal anomaly field model. A preliminary analysis of the geophysical structure of Broken Ridge is presented and unresolved questions are listed.

Using superconducting undulator for enhanced imaging capabilities of MaRIE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yampolsky, Nikolai

MaRIE x-ray free electron laser (FEL) is envisioned to deliver a burst of closely spaced in time pulses for enabling the capability of studying the dynamic processes in a sample. MaRIE capability can be largely enhanced using the superconducting undulator, which has the capability of doubling its period. This technology will allow reaching the photon energy as low as ~200-500 eV. As a result, the MaRIE facility will have a broader photon energy range enabling a larger variety of experiments. The soft x-ray capability is more likely to achieve the 3D imaging of dynamic processes in noncrystal materials than themore » hard x-ray capability alone.« less

Subradiant spontaneous undulator emission through collective suppression of shot noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratner, D.; Hemsing, E.; Gover, A.

The phenomenon of Dicke’s subradiance, in which the collective properties of a system suppress radiation, has received broad interest in atomic physics. Recent theoretical papers in the field of relativistic electron beams have proposed schemes to achieve subradiance through suppression of shot noise current fluctuations. The resulting “quiet” beam generates less spontaneous radiation than emitted even by a shot noise beam when oscillating in an undulator. Quiet beams could have diverse accelerator applications, including lowering power requirements for seeded free-electron lasers and improving efficiency of hadron cooling. In this paper we present experimental observation of a strong reduction in undulatormore » radiation, demonstrating the feasibility of noise suppression as a practical tool in accelerator physics.« less

Consideration of permanent tidal deformation in the orbit determination and data analysis for the Topex/Poseidon mission

NASA Technical Reports Server (NTRS)

Rapp, Richard H.; Nerem, R. Steven; Shum, C. K.; Klosko, Steven M.; Williamson, Ronald G.

1991-01-01

The effects of the permanent tidal effects of the Sun and Moon with specific applications to satellite altimeter data reduction are reviewed in the context of a consistent definition of geoid undulations. Three situations are applicable not only for altimeter reduction and geoid definition, but also for the second degree zonal harmonic of the geopotential and the equatorial radius. A recommendation is made that sea surface heights and geoid undulations placed on the Topex/Poseidon geophysical data record should be referred to the mean Earth case (i.e., with the permanent effects of the Sun and Moon included). Numerical constants for a number of parameters, including a flattening and geoid geopotential, are included.

Innovative FEL schemes using variable-gap undulators

NASA Astrophysics Data System (ADS)

Schneidmiller, E. A.; Yurkov, M. V.

2017-06-01

We discuss theoretical background and experimental verification of advanced schemes for X-ray FELs using variable gap undulators (harmonic lasing self-seeded FEL, reverse taper etc.) Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently this concept was successfully tested at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). Another innovative scheme that was tested at FLASH2 is the reverse tapering that can be used to produce circularly polarized radiation from a dedicated afterburner with strongly suppressed linearly polarized radiation from the main undulator. This scheme can also be used for an efficient background-free production of harmonics in an afterburner. Experiments on the frequency doubling that allowed to reach the shortest wavelength at FLASH as well as on post-saturation tapering to produce a record intencity in XUV regime are also discussed.

NOVEL CHAMBER DESIGN FOR AN IN-VACUUM CRYO-COOLED MINI-GAP UNDULATOR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

HU, J.-P.; FOERSTER, C.L.; SKARITKA, J.R.

2006-05-24

A stainless steel, Ultra-High Vacuum (UHV) chamber, featuring a large vertical rectangular port (53''W by 16''H), has been fabricated to house the one-meter magnet assembly of a newly installed undulator insertion device for beamline X-25 at the National Synchrotron Light Source. To achieve UHV, the new chamber is equipped with a differential ion pump, NEG pump, nude ion gauge, residual gas analyzer, and an all metal roughing valve. Temperature of the magnet assembly is maintained below 90 C during vacuum bake. The large rectangular port cover is sealed to the main flange of the chamber using a one-piece flat aluminummore » gasket and special sealing surfaces developed exclusively by Nor-Cal Products, Inc. The large flange provides easy access to the gap of the installed magnet girders for in situ magnetic measurements and shimming. Special window ports were designed into the cover and chamber for manipulation of optical micrometers external to the chamber to provide precise measurements of the in-vacuum magnet gap. The vacuum chamber assembly features independently vacuum-isolated feedthroughs that can be used for either water-or-cryogenic refrigeration-cooling of the monolithic magnet girders. This would allow for cryogenic-cooled permanent magnet operation and has been successfully tested within temperature range of +100 C to -150 C. Details of the undulator assembly for beamline X-25 is described in the paper.« less

The onset of layer undulations in smectic A liquid crystals due to a strong magnetic field

NASA Astrophysics Data System (ADS)

Contreras, A.; Garcia-Azpeitia, C.; García-Cervera, C. J.; Joo, S.

2016-08-01

We investigate the effect of a strong magnetic field on a three dimensional smectic A liquid crystal. We identify a critical field above which the uniform layered state loses stability; this is associated to the onset of layer undulations. In a previous work García-Cervera and Joo (2012 Arch. Ration. Mech. Anal. 203 1-43), García-Cervera and Joo considered the two dimensional case and analyzed the transition to the undulated state via a simple bifurcation. In dimension n  =  3 the situation is more delicate because the first eigenvalue of the corresponding linearized problem is not simple. We overcome the difficulties inherent to this higher dimensional setting by identifying the irreducible representations for natural actions on the functional that take into account the invariances of the problem thus allowing for reducing the bifurcation analysis to a subspace with symmetries. We are able to describe at least two bifurcation branches, highlighting the richer landscape of energy critical states in the three dimensional setting. Finally, we analyze a reduced two dimensional problem, assuming the magnetic field is very strong, and are able to relate this to a model in micromagnetics studied in Alouges et al (2002 ESAIM Control Optim. Calc. Var. 8 31-68), from where we deduce the periodicity property of minimizers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S. H.; Yang, B. X.; Collins, J. T.

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs),more » which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This study presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.« less

Analysis of baroreflex sensitivity during undulation pump ventricular assist device support.

PubMed

Liu, Hongjian; Shiraishi, Yasuyuki; Zhang, Xiumin; Song, Hojin; Saijo, Yoshifumi; Baba, Atsushi; Yambe, Tomoyuki; Abe, Yusuke; Imachi, Kou

2009-07-01

The aim of this study was to examine the baroreflex sensitivity (BRS), which involves the autonomic nervous system, in a goat with a chronically implanted undulation pump ventricular assist device (UPVAD). The UPVAD involved transforming the rotation of a brushless DC motor into an undulating motion by a disc attached via a special linking mechanism, and a jellyfish valve in the outflow cannula to prevent diastolic backflow. The pump was implanted into the thoracic cavity of a goat by a left thoracotomy, and the inflow and outflow cannulae were sutured to the apex of the left ventricle and to the descending aorta, respectively. The driving cable was wired percutaneously to an external controller. Electrocardiogram and hemodynamic waveforms were recorded at a sampling frequency of 1 kHz. BRS was determined when awake by the slope of the linear regression of R-R interval against mean arterial pressure changes, which were induced by the administration of methoxamine hydrochloride, both with continuous driving of the UPVAD as well as without assistance. BRS values during the UPVAD support and without assistance were 1.60 +/- 0.30 msec/mm Hg and 0.98 +/- 0.22 msec/mm Hg (n = 5, P < 0.05), respectively. BRS was significantly improved during left ventricular assistance. Therefore, UPVAD support might decrease sympathetic nerve activity and increase parasympathetic nerve activity to improve both microcirculation and organ function.

Experimental investigation of efficient locomotion of underwater snake robots for lateral undulation and eel-like motion patterns.

PubMed

Kelasidi, Eleni; Liljebäck, Pål; Pettersen, Kristin Y; Gravdahl, Jan T

2015-01-01

Underwater snake robots offer many interesting capabilities for underwater operations. The long and slender structure of such robots provide superior capabilities for access through narrow openings and within confined areas. This is interesting for inspection and monitoring operations, for instance within the subsea oil and gas industry and within marine archeology. In addition, underwater snake robots can provide both inspection and intervention capabilities and are thus interesting candidates for the next generation inspection and intervention AUVs. Furthermore, bioinspired locomotion through oscillatory gaits, like lateral undulation and eel-like motion, is interesting from an energy efficiency point of view. Increasing the motion efficiency in terms of the achieved forward speed by improving the method of propulsion is a key issue for underwater robots. Moreover, energy efficiency is one of the main challenges for long-term autonomy of these systems. In this study, we will consider both these two aspects of efficiency. This paper considers the energy efficiency of swimming snake robots by presenting and experimentally investigating fundamental properties of the velocity and the power consumption of an underwater snake robot for both lateral undulation and eel-like motion patterns. In particular, we investigate the relationship between the parameters of the gait patterns, the forward velocity and the energy consumption for different motion patterns. The simulation and experimental results are seen to support the theoretical findings.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caspi, S.; Schlueter, R.; Tatchyn, R.

Linac-driven X-Ray Free Electron Lasers (e.g., Linac Coherent Light Sources (LCLSs)), operating on the principle of single-pass saturation in the Self-Amplified Spontaneous Emission (SASE) regime typically require multi-GeV beam energies and undulator lengths in excess of tens of meters to attain sufficient gain in the 1{angstrom}--0.1{angstrom} range. In this parameter regime, the undulator structure must provide: (1) field amplitudes B{sub 0} in excess of 1T within periods of 4cm or less, (2) peak on-axis focusing gradients on the order of 30T/m, and (3) field quality in the 0.1%--0.3% range. In this paper the authors report on designs under consideration formore » a 4.5--1.5 {angstrom} LCLS based on superconducting (SC), hybrid/PM, and pulsed-Cu technologies.« less

Magnetic design of an Apple-X afterburner for the SASE3 undulator of the European XFEL

NASA Astrophysics Data System (ADS)

Li, Peng; Wei, Tao; Li, Yuhui; Pflueger, Joachim

2017-10-01

In its startup configuration the SASE3 beamline of the European XFEL provides only soft X-ray radiation, linearly polarized in the horizontal plane. In order to enhance capabilities of this beamline an afterburner scheme is proposed. It will be used as a coherent radiator using the micro-bunched electron beam of the linear SASE3 system. Radiation with variable polarization, which covers the full SASE3 wavelength range can be generated. For the radiator a new type of undulator design called Apple-X will be used. In this paper the design is described and magnet parameters, which are compatible with the SASE3 afterburner are determined using RADIA simulations. The end structure of such a device is optimized for minimum 1st field integrals.

Advanced photoelectric effect experiment beamline at Elettra: A surface science laboratory coupled with Synchrotron Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panaccione, G.; Vobornik, I.; Fujii, J.

2009-04-15

We report the main characteristics of the advanced photoelectric effect experiments beamline, operational at Elettra storage ring, featuring a fully independent double branch scheme obtained by the use of chicane undulators and able to keep polarization control in both linear and circular mode. The paper describes the novel technical solutions adopted, namely, (a) the design of a quasiperiodic undulator resulting in optimized suppression of higher harmonics over a large photon energy range (10-100 eV), (b) the thermal stability of optics under high heat load via cryocoolers, and (c) the end station interconnected setup allowing full access to off-beam and on-beammore » facilities and, at the same time, the integration of users' specialized sample growth chambers or modules.« less

Optical evaluation of the wave filtering properties of graded undulated lattices

NASA Astrophysics Data System (ADS)

Trainiti, G.; Rimoli, J. J.; Ruzzene, M.

2018-03-01

We investigate and experimentally demonstrate the elastic wave filtering properties of graded undulated lattices. Square reticulates composed of curved beams are characterized by graded mechanical properties which result from the spatial modulation of the curvature parameter. Among such properties, the progressive formation of frequency bandgaps leads to strong wave attenuation over a broad frequency range. The experimental investigation of wave transmission and the detection of full wavefields effectively illustrate this behavior. Transmission measurements are conducted using a scanning laser Doppler vibrometer, while a dedicated digital image correlation procedure is implemented to capture in-plane wave motion at selected frequencies. The presented results illustrate the broadband attenuation characteristics resulting from spatial grading of the lattice curvature, whose in-depth investigation is enabled by the presented experimental procedures.

Energy optimization of a regular macromolecular crystallography beamline for ultra-high-resolution crystallography

DOE PAGES

Rosenbaum, Gerd; Ginell, Stephan L.; Chen, Julian C.-H.

2015-01-01

In this study, a practical method for operating existing undulator synchrotron beamlines at photon energies considerably higher than their standard operating range is described and applied at beamline 19-ID of the Structural Biology Center at the Advanced Photon Source enabling operation at 30 keV. Adjustments to the undulator spectrum were critical to enhance the 30 keV flux while reducing the lower- and higher-energy harmonic contamination. A Pd-coated mirror and Al attenuators acted as effective low- and high-bandpass filters. The resulting flux at 30 keV, although significantly lower than with X-ray optics designed and optimized for this energy, allowed for accuratemore » data collection on crystals of the small protein crambin to 0.38 Å resolution.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruland, Robert

The Visible-Infrared SASE Amplifier (VISA) undulator consists of four 99cm long segments. Each undulator segment is set up on a pulsed-wire bench, to characterize the magnetic properties and to locate the magnetic axis of the FODO array. Subsequently, the location of the magnetic axis, as defined by the wire, is referenced to tooling balls on each magnet segment by means of a straightness interferometer. After installation in the vacuum chamber, the four magnet segments are aligned with respect to themselves and globally to the beam line reference laser. A specially designed alignment fixture is used to mount one straightness interferometermore » each in the horizontal and vertical plane of the beam. The goal of these procedures is to keep the combined rms trajectory error, due to magnetic and alignment errors, to 50{micro}m.« less

Measurement of movements in the ionosphere using radio reflections

NASA Astrophysics Data System (ADS)

Whitehead, J. D.; From, W. R.; Jones, K. L.; Monro, P. E.

1983-05-01

Movements of the ionosphere may be measured using radio reflections either by observing the movement of the diffraction, or interference, pattern along the ground; or by using the Doppler shifts of the echo as a radar beam is scanned across the sky. The two methods may use the same experimental arrangement and even the same data. The error in the drift velocity measured for scattered echoes is inversely proportional to the square of the array size for both methods. More detail of the random motion may be observed with the Doppler method. When the radio reflections are from an undulating surface in the ionosphere which changes its form as it moves, the Doppler method combined with further analysis is required to measure the movement and change of the undulating surface.

Scaling EUV and X-ray Thomson sources to optical free-electron laser operation with traveling-wave Thomson scattering (Conference Presentation)

NASA Astrophysics Data System (ADS)

Steiniger, Klaus; Albach, Daniel; Debus, Alexander; Loeser, Markus; Pausch, Richard; Roeser, Fabian; Schramm, Ulrich; Siebold, Matthias; Bussmann, Michael

2017-05-01

Traveling-Wave Thomson-Scattering (TWTS) allows for the realization of optical free-electron lasers (OFELs) from the interaction of short, high-power laser pulses with brilliant relativistic electron bunches. The laser field provides the optical undulator which is traversed by the electrons. In order to achieve coherent amplification of radiation through electron microbunching the interaction between electrons and laser must be maintained over hundreds to thousands of undulator periods. Traveling-Wave Thomson-Scattering is the only scattering geometry so far allowing for the realization of optical undulators of this length which is at the same time scalable from extreme ultraviolet to X-ray photon energies. TWTS is also applicable for the realization of incoherent high peak brightness hard X-ray to gamma-ray sources which can provide orders of magnitude higher photon output than classic head-on Thomson sources. In contrast to head-on Thomson sources TWTS employs a side-scattering geometry where laser and electron propagation direction of motion enclose an angle. Tilting the laser pulse front with respect to the wave front by half of this interaction angle optimizes electron and laser pulse overlap. In the side-scattering geometry the tilt of the pulse-front compensates the spatial offset between electrons and laser pulse-front which would be present otherwise for an electron bunch far from the interaction point where it overlaps with the laser pulse center. Thus the laser pulse-front tilt ensures continuous overlap between laser pulse and electrons while these traverse the laser pulse cross-sectional area. This allows to control the interaction distance in TWTS by the laser pulse width rather than laser pulse duration as is the case for head-on Thomson scattering. Utilizing petawatt class laser pulses with millimeter to centimeter scale width allows for the realization of compact optical undulators with thousands of periods. When laser pulses for TWTS are prepared, care has to be taken of laser dispersion. Especially for scenarios featuring interaction angles of several ten to over one hundred degree the angular dispersion originating from laser pulse-front tilt can significantly prolong the pulse duration during the interaction which leads to a decrease in optical undulator amplitude and eventually terminates the interaction long before the target interaction distance is reached. In the talk it is shown how a pair of two gratings can be used to first generate the pulse-front tilt and second control and compensate dispersion during the interaction by utilizing the plane of optimum compression. Furthermore an experimental setup strategy is presented allowing for an interaction outside the laser pulse focus. This is a necessity for TWTS OFELs requiring focusing to reach optical undulator strengths on the order of unity since the centimeter scale laser pulse width at the interaction point result in turn in Rayleigh lengths on the order of one hundred meter and thus in laser focusing distances of several hundred meter. The talk shows how an out-of-focus interaction geometry utilizing strong focusing of the incident laser pulse needs to be designed in order to regain compactness by reducing the focusing distance by one to two orders of magnitude.

Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

NASA Astrophysics Data System (ADS)

Magnini, M.; Beisel, A. M.; Ferrari, A.; Thome, J. R.

2017-11-01

The fluid mechanics of elongated bubbles in confined gas-liquid flows in micro-geometries is important in pore-scale flow processes for enhanced oil recovery and mobilization of colloids in unsaturated soil. The efficiency of such processes is traditionally related to the thickness of the liquid film trapped between the elongated bubble and the pore's wall, which is assumed constant. However, the surface of long bubbles presents undulations in the vicinity of the rear meniscus, which may significantly decrease the local thickness of the liquid film, thus impacting the process of interest. This study presents a systematic analysis of these undulations and the minimum film thickness induced in the range Ca = 0.001- 0.5 and Re = 0.1- 2000 . Pore-scale Computational Fluid Dynamics (CFD) simulations are performed with a self-improved version of the opensource solver ESI OpenFOAM which is based on a Volume of Fluid method to track the gas-liquid interface. A lubrication model based on the extension of the classical axisymmetric Bretherton theory is utilized to better understand the CFD results. The profiles of the rear meniscus of the bubble obtained with the lubrication model agree fairly well with those extracted from the CFD simulations. This study shows that the Weber number of the flow, We = Ca Re , is the parameter that best describes the dynamics of the interfacial waves. When We < 0.1, a single wave crest is observed and the minimum film thickness tends to an asymptotic value, which depends on the capillary number, as We → 0. Undulations dampen as the capillary number increases and disappear completely when Ca = 0.5 . When We > 0.1, a larger number of wave crests becomes evident on the surface of the rear meniscus of the bubble. The liquid film thickness at the crests of the undulations thins considerably as the Reynolds number is increased, down to less than 60% of the value measured in the flat film region. This may significantly influence important environmental processes, such as the detachment and mobilization of micron-sized pollutants and pathogenic micro-organisms adhering at the pore's wall in unsaturated soil.

South Polar Designs

NASA Image and Video Library

2006-04-29

This MOC image shows an undulating scene in the south polar region of Mars. Small, elevated mesas of smooth, relatively homogeneous-appearing material are separated by low-lying regions that are speckled and darkened in some local areas

Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics.

PubMed

Chen, Sen; Luo, Sheng Nian

2018-03-01

Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10-100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are explored via Gaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamental harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.

Mean gravity anomalies and sea surface heights derived from GEOS-3 altimeter data

NASA Technical Reports Server (NTRS)

Rapp, R. H.

1978-01-01

Approximately 2000 GEOS-3 altimeter arcs were analyzed to improve knowledge of the geoid and gravity field. An adjustment procedure was used to fit the sea surface heights (geoid undulations) in an adjustment process that incorporated cross-over constraints. The error model used for the fit was a one or two parameter model which was designed to remove altimeter bias and orbit error. The undulations on the adjusted arcs were used to produce geoid maps in 20 regions. The adjusted data was used to derive 301 5 degree equal area anomalies and 9995 1 x 1 degree anomalies in areas where the altimeter data was most dense, using least squares collocation techniques. Also emphasized was the ability of the altimeter data to imply rapid anomaly changes of up to 240 mgals in adjacent 1 x 1 degree blocks.

Stability analysis of nanoscale surface patterns in stressed solids

NASA Astrophysics Data System (ADS)

Kostyrko, Sergey A.; Shuvalov, Gleb M.

2018-05-01

Here, we use the theory of surface elasticity to extend the morphological instability analysis of stressed solids developed in the works of Asaro, Tiller, Grinfeld, Srolovitz and many others. Within the framework of Gurtin-Murdoch model, the surface phase is assumed to be a negligibly thin layer with the elastic properties which differ from those of the bulk material. We consider the mass transport mechanism driven by the variation of surface and bulk energy along undulated surface of stressed solid. The linearized surface evolution equation is derived in the case of plane strain conditions and describes the amplitude change of surface perturbations with time. A parametric analysis of this equation leads to the definition of critical conditions which depend on undulation wavelength, residual surface stress, applied loading, surface and bulk elastic constants and predict the surface morphological stability.

Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Sen; Luo, Sheng-Nian

Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10–100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are exploredviaGaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamentalmore » harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.« less

Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakeman, M. S.; Lawrence Berkeley National Laboratory, Berkeley, California 94720; Tilborg, J. van

We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placementmore » of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.« less

High-gain thompson-scattering X-ray free-electron laser by time-synchronic laterally tilted optical wave

DOEpatents

Chang, Chao; Tang, Chuanxiang; Wu, Juhao

2017-05-09

An improved optical undulator for use in connection with free electron radiation sources is provided. A tilt is introduced between phase fronts of an optical pulse and the pulse front. Two such pulses in a counter-propagating geometry overlap to create a standing wave pattern. A line focus is used to increase the intensity of this standing wave pattern. An electron beam is aligned with the line focus. The relative angle between pulse front and phase fronts is adjusted such that there is a velocity match between the electron beam and the overlapping optical pulses along the line focus. This allows one to provide a long interaction length using short and intense optical pulses, thereby greatly increasing the radiation output from the electron beam as it passes through this optical undulator.

Ray tracing: Experience at SRC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Severson, M.

1996-09-01

SHADOW [B. Lai and F. Cerrina, Nucl. Instrum. Methods A {bold 246}, 337 (1986)] is the primary ray-tracing program used at SRC. Ray tracing provides a tremendous amount of information regarding beamline layout, mirror sizes, resolution, alignment tolerances, and beam size at various locations. It also provides a way to check the beamline design for errors. Two recent designs have been ray traced extensively: an undulator-based, 4-meter, normal-incidence monochromator (NIM) [R. Reininger, M.C. Severson, R.W.C. Hansen, W.R. Winter, M.A. Green, and W.S. Trzeciak, Rev. Sci. Instrum. {bold 66}, 2194 (1995)] and an undulator-based, plane-grating monochromator (PGM) [R. Reininger, S.L. Crossley,more » M.A. Lagergren, M.C. Severson, and R.W.C. Hansen, Nucl. Instrum. Methods A {bold 347}, 304 (1994)]. {copyright} {ital 1996 American Institute of Physics.}« less

The Advanced Light Source Elliptically Polarizing Undulator

NASA Astrophysics Data System (ADS)

Marks, Steve; Cortopassi, Christopher; Devries, Jan; Hoyer, Egon; Leinbach, Robert; Minamihara, Yoshi; Padmore, Howard; Pipersky, Paul; Plate, Dave; Schlueter, Ross; Young, Anthony

1997-05-01

An elliptically polarizing undulator for the Advanced Light Source has been designed and is currently under construction. The magnetic design is a four quadrant pure permanent magnet structure featuring moveable magnets to correct phase errors and on axis field integrals. The device is designed with a 5.0 cm period and will produce variably polarized light of any ellipticity, including pure circular and linear. The spectral range at 1.9 GeV for typical elliptical polarization with a degree of circular polarization greater than 0.8 will be from 100 eV to 1500 eV, using the third and fifth spectral harmonics. The device will be switchabe between left and right circular modes at a frequency of up to 0.1 Hz. The 1.95 m long overall length will allow two such devices in a single ALS straight sector.

Measuring ionospheric movements using totally reflected radio waves

NASA Astrophysics Data System (ADS)

Sadler, Elaine M.; Whitehead, J. D.; From, W. R.

1988-02-01

It is shown that for radio waves of a particular frequency reflected totally from the ionosphere the effect of refraction as well as reflection can be simulated by an effective reflecting surface. This mirror-like surface will give the correct angle of arrival and Doppler shift for all radars operating at this frequency. It is theoretically possible for the effective reflecting surface to be folded back on itself, but this is unlikely except for F-region echoes refracted by sporadic E-clouds. If the surface is not folded and exists everywhere, it is always possible to describe its motion and change in terms of wave undulations. Experimental data for F-region echoes show that these wave undulations are very dispersive. However, the matching between the best fitting model and the experimental data is worse than expected for reasons we do not understand.

Measuring ionospheric movements using totally reflected radio waves

NASA Astrophysics Data System (ADS)

From, W. R.; Sadler, Elaine M.; Whitehead, J. D.

1988-02-01

It is shown that for radio waves of a particular frequency reflected totally from the ionosphere the effect of refraction as well as reflection can be simulated by an effective reflecting surface. This mirrorlike surface will give the correct angle of arrival and Doppler shift for all radars operating at this frequency. It is theoretically possible for the effective reflecting surface to be folded back on itself, but this is unlikely except for F-region echoes refracted by sporadic E-clouds. If the surface is not folded and exists everywhere, it is always possible to describe its motion and change in terms of wave undulations. Experimental data for F-region echoes show that these wave undulations are very dispersive. However, the matching between the best fitting model and the experimental data is worse than expected for reasons we do not understand.

Thermal management and prototype testing of Compton scattering X-ray beam position monitor for the Advanced Photon Source Upgrade

NASA Astrophysics Data System (ADS)

Lee, S. H.; Yang, B. X.; Collins, J. T.; Ramanathan, M.

2017-02-01

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs), which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This paper presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.

Thermo-mechanical analysis of a user filter assembly for undulator/wiggler operations at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nian, H.L.T.; Kuzay, T.M.; Collins, J.

1996-12-31

This paper reports a thermo-mechanical study of a beamline filter (user filter) for undulator/wiggler operations. It is deployed in conjunction with the current commissioning window assembly on the APS insertion device (ID) front ends. The beamline filter at the Advanced Photon Source (APS) will eventually be used in windowless operations also. Hence survival and reasonable life expectancy of the filters under intense insertion device (ID) heat flu are crucial to the beamline operations. To accommodate various user requirements, the filter is configured to be a multi-choice type and smart to allow only those filter combinations that will be safe tomore » operate with a given ring current and beamline insertion device gap. However, this paper addresses only the thermo-mechanical analysis of individual filter integrity and safety in all combinations possible. The current filter design is configured to have four filter frames in a cascade with each frame holding five filters. This allows a potential 625 total filter combinations. Thermal analysis for all of these combinations becomes a mammoth task considering the desired choices for filter materials (pyrolitic graphite and metallic filters), filter thicknesses, undulator gaps, and the beam currents. The paper addresses how this difficult task has been reduced to a reasonable effort and computational level. Results from thermo-mechanical analyses of the filter combinations are presented both in tabular and graphical format.« less

Comparison of Achievable Magnetic Fields with Superconducting and Cryogenic Permanent Magnet Undulators – A Comprehensive Study of Computed and Measured Values

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moog, E. R.; Dejus, R. J.; Sasaki, S.

2017-01-01

Magnetic modeling was performed to estimate achievable magnetic field strengths of superconducting undulators (SCUs) and to compare them with those of cryogenically cooled permanent magnet undulators (CPMUs). Starting with vacuum (beam stay-clear) gaps of 4.0 and 6.0 mm, realistic allowances for beam chambers (in the SCU case) and beam liners (in the CPMU case) were added. (A 6.0-mm vacuum gap is planned for the upgraded APS). The CPMU magnetic models consider both CPMUs that use NdFeB magnets at ~150 K and PrFeB magnets at 77 K. Parameters of the magnetic models are presented along with fitted coefficients of a Halbach-typemore » expression for the field dependence on the gap-to-period ratio. Field strengths for SCUs are estimated using a scaling law for planar SCUs; an equation for that is given. The SCUs provide higher magnetic fields than the highest-field CPMUs – those using PrFeB at 77 K – for period lengths longer than ~14 mm for NbTi-based SCUs and ~10 mm for Nb3Sn-based SCUs. To show that the model calculations and scaling law results are realistic, they are compared to CPMUs that have been built and NbTi-based SCUs that have been built. Brightness tuning curves of CPMUs (PrFeB) and SCUs (NbTi) for the upgraded APS lattice are also provided for realistic period lengths.« less

Thermal management and prototype testing of Compton scattering X-ray beam position monitor for the Advanced Photon Source Upgrade.

PubMed

Lee, S H; Yang, B X; Collins, J T; Ramanathan, M

2017-02-01

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs), which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This paper presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.

Stability of a thin elastic film close to a rigid plate

NASA Astrophysics Data System (ADS)

Chen, Yi-chao; Fried, Eliot; Tortorelli, Daniel A.

2012-05-01

We introduce and study a variational model for the formation of patterns induced by bringing the surface of a rigid plate into contact proximity with the surface of a polymeric film strongly bonded to a substrate. We treat the film as a homogeneous, isotropic, hyperelastic solid and account for both attractive and repulsive van der Waals interactions between the film surface and the proximate contractor. Aside from confirming the intuitive expectation that the presence of a repulsive contribution to the van der Waals potential should stabilize patterns that form on the film surface, we elucidate the role of repulsive interactions at the onset of instability. For a recently proposed van der Waals potential involving two parameters, the Hamaker constant A and the equilibrium spacing de, our results include estimates for the critical gap dc at which undulations appear on the film surface, the corresponding wavenumber kc of the undulations, and a lower bound fm for the attractive force needed to induce the undulations. To leading order, dc˜(Ah/μ), kc˜1/h, and fm˜(μ3A/h3), where h and μ denote the thickness and infinitesimal shear modulus of the film. Correction terms due to repulsive interactions indicate that, while kc may be influenced by μ and A, dc may also be influenced by de. Granted knowledge of μ and A, our results also suggest a simple experimental protocol for determining de.

Source characteristics and design consideration for an iron-free variable-period/polarizing undulator for the UV/VUV range on SPEAR (abstract)

NASA Astrophysics Data System (ADS)

Tatchyn, Roman

1992-01-01

Insertion devices that are tuned by electrical period variation are particularly suited for the design of flexible polarized-light sources [R. Tatchyn, J. Appl. Phys. 65, 4107 (1989); R. Tatchyn and T. Cremer, IEEE Trans. Mag. 26, 3102 (1990)]. Important advantages vis-a-vis mechanical or hybrid variable field designs include: (1) significantly more rapid modulation of both polarization and energy, (2) an inherently larger set of polarization modulation capabilities and (3) polarization/energy modulation at continuously optimized values of K. In this paper we outline some of the general considerations that enter into the design of hysteresis-free variable-period/polarizing undulator structures and present the parameters of a recently-completed prototype design capable of generating intense levels of UV/VUV photon flux on SPEAR running at 3 GeV.

Fish-like propulsion of an airship with planar membrane dielectric elastomer actuators.

PubMed

Jordi, C; Michel, S; Fink, E

2010-06-01

The goal of our project is to mimic fish-like movement in air, propelling an airship by undulating its hull and a caudal fin. The activation of the fish-like body in air is realized by dielectric elastomers. These actuators are quite unique for their soft light-weight membrane structure and they are therefore very appropriate to the application on inflated structures. The principles of biomimetics for the structural design and movement are discussed and the conception and design of the airship is described. Various development tests, including wind tunnel testing and flight trials, were performed and the results obtained are presented. It can be shown that an 8 m model airship can be propelled in a fish-like manner in air and that the propulsion can be drastically improved by undulating the body as well as the caudal fin contrary to propulsion with only the caudal fin.

Biophysical Properties of Plasmodium falciparum-Infected Erythrocytes from Novel Analysis of the Flicker Phenomena

NASA Astrophysics Data System (ADS)

Arie, Takayuki; Jin, Albert; Dvorak, James

2002-03-01

Infectious processes often modulate the intrinsic properties of vertebrate cells. We studied the modulation of human erythrocyte flicker during the intra-erythrocytic cycle of Plasmodium falciparum malaria using video microscopy imaging and a data analysis system of our design to extract flicker spectra and lateral cell edge undulations of individual erythrocytes at various stages of infection. The total flicker power, the power weighted mean flicker frequency, the mode amplitudes of lateral undulations, and the time correlation of translation mode was quantified by infectious stage and modeled theoretically. Our results suggest that malaria-infected erythrocytes become increasingly more rigid following infection and provide an insight into the modulation of erythrocyte cytoplasmic viscosity by the parasites. These studies of malaria-infected erythrocytes elucidate the kinetics of both membrane and cellular changes that are relevant to blood microcirculation and improve our understanding of the malaria disease process.

Why do worms go against the flow? C. elegans behaviors explained by simple physics

PubMed Central

Bau, Haim H; Raizen, David; Yuan, Jinzhou

2015-01-01

Nearly half a century of neurobiological research using the nematode Caenorahbitis elegans has produced a remarkably detailed understanding of how genotype controls behavioral phenotype. However, the role of simple physical forces in regulating behavior has been understudied. Here, we review our recent observations of 3 behaviors of C. elegans suspended in solution that can be fully explained by the laws of mechanics. These behaviors are bordertaxis, the attraction toward solid surfaces; positive rheotaxis, the propensity to swim against the flow; and synchrophilia, the tendency of animals when close to each other to synchronize their gaits. Although these 3 behaviors are not directly regulated by the animal's nervous system, bordertaxis and rheotaxis require the animal to have an undulating gait. We conjecture that these behaviors are advantageous to the animals, and thus evolution may have favored microorganism that swim with an undulating gait. PMID:27123373

Development of a Single-Pass Amplifier for an Optical Stochastic Cooling Proof-of-Principle Experiment at Fermilab's IOTA Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andorf, M. B.; Lebedev, V. A.; Piot, P.

2015-06-01

Optical stochastic cooling (OSC) is a method of beam cooling which is expected to provide cooling rates orders of magnitude larger than ordinary stochastic cooling. Light from an undulator (the pickup) is amplified and fed back onto the particle beam via another undulator (the kicker). Fermilab is currently exploring a possible proof-of-principle experiment of the OSC at the integrable-optics test accelerator (IOTA) ring. To implement effective OSC a good correction of phase distortions in the entire band of the optical amplifier is required. In this contribution we present progress in experimental characterization of phase distortions associated to a Titanium Sapphiremore » crystal laser-gain medium (a possible candidate gain medium for the OSC experiment to be performed at IOTA). We also discuss a possible option for a mid-IR amplifier« less

NSLS-II storage ring insertion device and front-end commissioning and operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G., E-mail: gwang@bnl.gov; Shaftan, T.; Amundsen, C.

The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source at Brookhaven National Laboratory. During spring/ summer of 2014, the storage ring was commissioned up to 50 mA without insertion devices. In the fall of 2014, we began commissioning of the project beamlines, which included seven insertion devices on six ID ports. Beamlines IXS, HXN, CSX-1, CSX-2, CHX, SRX, and XPD-1 consist of elliptically polarized undulator (EPU), damping wigglers (DW) and in-vacuum undulators (IVU) covering from VUV to hard x-ray range. In this paper, experience with commissioning and operation is discussed.more » We focus on reaching storage ring performance with IDs, including injection, design emittance, compensation of orbit distortions caused by ID residual field, source point stability, beam alignment and tools for control, monitoring and protection of the ring chambers from ID radiation.« less

The prediction and mapping of geoidal undulations from GEOS-3 altimetry. [gravity anomalies

NASA Technical Reports Server (NTRS)

Kearsley, W.

1978-01-01

From the adjusted altimeter data an approximation to the geoid height in ocean areas is obtained. Methods are developed to produce geoid maps in these areas. Geoid heights are obtained for grid points in the region to be mapped, and two of the parameters critical to the production of an accurate map are investigated. These are the spacing of the grid, which must be related to the half-wavelength of the altimeter signal whose amplitude is the desired accuracy of the contour; and the method adopted to predict the grid values. Least squares collocation was used to find geoid undulations on a 1 deg grid in the mapping area. Twenty maps, with their associated precisions, were produced and are included. These maps cover the Indian Ocean, Southwestern and Northeastern portions of the Pacific Ocean, and Southwest Atlantic and the U.S. Calibration Area.

Observation of self-excited acoustic vortices in defect-mediated dust acoustic wave turbulence.

PubMed

Tsai, Ya-Yi; I, Lin

2014-07-01

Using the self-excited dust acoustic wave as a platform, we demonstrate experimental observation of self-excited fluctuating acoustic vortex pairs with ± 1 topological charges through spontaneous waveform undulation in defect-mediated turbulence for three-dimensional traveling nonlinear longitudinal waves. The acoustic vortex pair has helical waveforms with opposite chirality around the low-density hole filament pair in xyt space (the xy plane is the plane normal to the wave propagation direction). It is generated through ruptures of sequential crest surfaces and reconnections with their trailing ruptured crest surfaces. The initial rupture is originated from the amplitude reduction induced by the formation of the kinked wave crest strip with strong stretching through the undulation instability. Increasing rupture causes the separation of the acoustic vortex pair after generation. A similar reverse process is followed for the acoustic vortex annihilating with the opposite-charged acoustic vortex from the same or another pair generation.

Viscous Dynamics of Lyme Disease and Syphilis Spirochetes Reveal Flagellar Torque and Drag

PubMed Central

Harman, Michael; Vig, Dhruv K.; Radolf, Justin D.; Wolgemuth, Charles W.

2013-01-01

The spirochetes that cause Lyme disease (Borrelia burgdorferi) and syphilis (Treponema pallidum) swim through viscous fluids, such as blood and interstitial fluid, by undulating their bodies as traveling, planar waves. These undulations are driven by rotation of the flagella within the periplasmic space, the narrow (∼20–40 nm in width) compartment between the inner and outer membranes. We show here that the swimming speeds of B. burgdorferi and T. pallidum decrease with increases in viscosity of the external aqueous milieu, even though the flagella are entirely intracellular. We then use mathematical modeling to show that the measured changes in speed are consistent with the exertion of constant torque by the spirochetal flagellar motors. Comparison of simulations, experiments, and a simple model for power dissipation allows us to estimate the torque and resistive drag that act on the flagella of these major spirochetal pathogens. PMID:24268139

Performance of Saga-University Beamline with Planer Undulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azuma, J.; Takahashi, K.; Kamada, M.

2010-06-23

A planer undulator consisted of 24 periods of an 85-mm length has been installed in a 2.7-m straight section of the SAGA-LS, in order to provide brilliant soft x-rays for advanced researches on nano-surfaces and interfaces at the Saga-university beamline BL13. The photon flux of 2x10{sup 11} photons/100 mA was obtained at 133 eV, and the available photon energy was beyond 800 eV using higher harmonics. The achieved resolving power of the varied-line-spacing (VLS) monochromator system was 8,670 at 130 eV with slits of 15 um. This agrees very well with the value of 8,790 expected from the ray-tracing calculation.more » The details in the performance tests will be reported, indicating the high performance of the beamline BL13 for photoelectron spectroscopy in the soft x-ray region.« less

Convergent evolution in locomotory patterns of flying and swimming animals.

PubMed

Gleiss, Adrian C; Jorgensen, Salvador J; Liebsch, Nikolai; Sala, Juan E; Norman, Brad; Hays, Graeme C; Quintana, Flavio; Grundy, Edward; Campagna, Claudio; Trites, Andrew W; Block, Barbara A; Wilson, Rory P

2011-06-14

Locomotion is one of the major energetic costs faced by animals and various strategies have evolved to reduce its cost. Birds use interspersed periods of flapping and gliding to reduce the mechanical requirements of level flight while undergoing cyclical changes in flight altitude, known as undulating flight. Here we equipped free-ranging marine vertebrates with accelerometers and demonstrate that gait patterns resembling undulating flight occur in four marine vertebrate species comprising sharks and pinnipeds. Both sharks and pinnipeds display intermittent gliding interspersed with powered locomotion. We suggest, that the convergent use of similar gait patterns by distinct groups of animals points to universal physical and physiological principles that operate beyond taxonomic limits and shape common solutions to increase energetic efficiency. Energetically expensive large-scale migrations performed by many vertebrates provide common selection pressure for efficient locomotion, with potential for the convergence of locomotory strategies by a wide variety of species.

CSEM-Steel hybrid wiggler/undulator magnetic field studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halbach, K.; Hoyer, E.; Marks, S.

1985-06-01

Current design of permanent magnet wiggler/undulators use either pure charge sheet equivalent material (CSEM) or the CSEM-Steel hybrid configuration. Hybrid configurations offer higher field strength at small gaps, field distributions dominated by the pole surfaces and pole tuning. Nominal performance of the hybrid is generally predicted using a 2-D magnetic design code neglecting transverse geometry. Magnetic measurements are presented showing transverse configuration influence on performance, from a combination of models using CSEMs, REC (H/sub c/ = 9.2 KOe) and NdFe (H/sub c/ = 10.7 kOe), different pole widths and end configurations. Results show peak field improvement using NdFe in placemore » of REC in identical models, gap peak field decrease with pole width decrease (all results less than computed 2-D fields), transverse gap field distributions, and importance of CSEM material overhanging the poles in the transverse direction for highest gap fields. 3 refs., 6 figs.« less

A possible relation between flare activity in super-luminous supernovae and gamma-ray bursts

NASA Astrophysics Data System (ADS)

Yu, Yun-Wei; Li, Shao-Ze

2017-09-01

Significant undulations appear in the light curve of a recently discovered super-luminous supernova (SLSN) SN 2015bn after the first peak, while the underlying profile of the light curve can be explained well by a continuous energy supply from a central engine, possibly the spin-down of a millisecond magnetar. We propose that these undulations are caused by an intermittent pulsed energy supply, indicating the energetic flare activity of the central engine of the SLSN. Many post-burst flares were discovered during X-ray afterglow observations of gamma-ray bursts (GRBs). We find that the SLSN flares described here approximately obey the empirical correlation between the luminosity and time-scale of GRB flares, extrapolated to the relevant longer time-scales of SLSN flares. This somewhat confirms the possible connection between these two different phenomena, as recently suggested by Yu et al.

Stiffening of fluid membranes due to thermal undulations: density-matrix renormalization-group study.

PubMed

Nishiyama, Yoshihiro

2002-12-01

It has been considered that the effective bending rigidity of fluid membranes should be reduced by thermal undulations. However, recent thorough investigation by Pinnow and Helfrich revealed the significance of measure factors for the partition sum. Accepting the local curvature as a statistical measure, they found that fluid membranes are stiffened macroscopically. In order to examine this remarkable idea, we performed extensive ab initio simulations for a fluid membrane. We set up a transfer matrix that is diagonalized by means of the density-matrix renormalization group. Our method has an advantage, in that it allows us to survey various statistical measures. As a consequence, we found that the effective bending rigidity flows toward strong coupling under the choice of local curvature as a statistical measure. On the contrary, for other measures such as normal displacement and tilt angle, we found a clear tendency toward softening.

Ellipsoidal corrections for geoid undulation computations using gravity anomalies in a cap

NASA Technical Reports Server (NTRS)

Rapp, R. H.

1981-01-01

Ellipsoidal correction terms have been derived for geoid undulation computations when the Stokes equation using gravity anomalies in a cap is combined with potential coefficient information. The correction terms are long wavelength and depend on the cap size in which its gravity anomalies are given. Using the regular Stokes equation, the maximum correction for a cap size of 20 deg is -33 cm, which reduces to -27 cm when the Stokes function is modified by subtracting the value of the Stokes function at the cap radius. Ellipsoidal correction terms were also derived for the well-known Marsh/Chang geoids. When no gravity was used, the correction could reach 101 cm, while for a cap size of 20 deg the maximum correction was -45 cm. Global correction maps are given for a number of different cases. For work requiring accurate geoid computations these correction terms should be applied.

Sub-micron resolution rf cavity beam position monitor system at the SACLA XFEL facility

NASA Astrophysics Data System (ADS)

Maesaka, H.; Ego, H.; Inoue, S.; Matsubara, S.; Ohshima, T.; Shintake, T.; Otake, Y.

2012-12-01

We have developed and constructed a C-band (4.760 GHz) rf cavity beam position monitor (RF-BPM) system for the XFEL facility at SPring-8, SACLA. The demanded position resolution of the RF-BPM is less than 1 μm, because an electron beam and x-rays must be overlapped within 4 μm precision in the undulator section for sufficient FEL interaction between the electrons and x-rays. In total, 57 RF-BPMs, including IQ demodulators and high-speed waveform digitizers for signal processing, were produced and installed into SACLA. We evaluated the position resolutions of 20 RF-BPMs in the undulator section by using a 7 GeV electron beam having a 0.1 nC bunch charge. The position resolution was measured to be less than 0.6 μm, which was sufficient for the XFEL lasing in the wavelength region of 0.1 nm, or shorter.

Description of two species of early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp.

PubMed

Okamoto, Noriko; Horák, Aleš; Keeling, Patrick J

2012-01-01

In alveolate evolution, dinoflagellates have developed many unique features, including the cell that has epicone and hypocone, the undulating transverse flagellum. However, it remains unclear how these features evolved. The early branching dinoflagellates so far investigated such as Hematodinium, Amoebophrya and Oxyrrhis marina differ in many ways from of core dinoflagellates, or dinokaryotes. Except those handful of well studied taxa, the vast majority of early branching dinoflagellates are known only by environmental sequences, and remain enigmatic. In this study we describe two new species of the early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp. from marine intertidal sandy beach. Molecular phylogeny of the small subunit (SSU) ribosomal RNA and Hsp90 gene places Psammosa spp. as an early branch among the dinoflagellates. Morphologically (1) they lack the typical dinoflagellate epicone-hypocone structure, and (2) undulation in either flagella. Instead they display a mosaïc of dinokaryotes traits, i.e. (3) presence of bi-partite trychocysts; Oxyrrhis marina-like traits, i.e. (4) presence of flagellar hairs, (5) presence of two-dimensional cobweb scales ornamenting both flagella (6) transversal cell division; a trait shared with some syndineansand Parvilucifera spp. i.e. (7) a nucleus with a conspicuous nucleolus and condensed chromatin distributed beneath the nuclear envelope; as well as Perkinsus marinus -like features i.e. (8) separate ventral grooves where flagella emerge and (9) lacking dinoflagellate-type undulating flagellum. Notably Psammosa retains an apical complex structure, which is shared between perkinsids, colpodellids, chromerids and apicomplexans, but is not found in dinokaryotic dinoflagellates.

Description of Two Species of Early Branching Dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp

PubMed Central

Okamoto, Noriko; Horák, Aleš; Keeling, Patrick J.

2012-01-01

In alveolate evolution, dinoflagellates have developed many unique features, including the cell that has epicone and hypocone, the undulating transverse flagellum. However, it remains unclear how these features evolved. The early branching dinoflagellates so far investigated such as Hematodinium, Amoebophrya and Oxyrrhis marina differ in many ways from of core dinoflagellates, or dinokaryotes. Except those handful of well studied taxa, the vast majority of early branching dinoflagellates are known only by environmental sequences, and remain enigmatic. In this study we describe two new species of the early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp. from marine intertidal sandy beach. Molecular phylogeny of the small subunit (SSU) ribosomal RNA and Hsp90 gene places Psammosa spp. as an early branch among the dinoflagellates. Morphologically (1) they lack the typical dinoflagellate epicone–hypocone structure, and (2) undulation in either flagella. Instead they display a mosaïc of dinokaryotes traits, i.e. (3) presence of bi-partite trychocysts; Oxyrrhis marina–like traits, i.e. (4) presence of flagellar hairs, (5) presence of two-dimensional cobweb scales ornamenting both flagella (6) transversal cell division; a trait shared with some syndineansand Parvilucifera spp. i.e. (7) a nucleus with a conspicuous nucleolus and condensed chromatin distributed beneath the nuclear envelope; as well as Perkinsus marinus -like features i.e. (8) separate ventral grooves where flagella emerge and (9) lacking dinoflagellate-type undulating flagellum. Notably Psammosa retains an apical complex structure, which is shared between perkinsids, colpodellids, chromerids and apicomplexans, but is not found in dinokaryotic dinoflagellates. PMID:22719825

Contribution of collagen fiber undulation to regional biomechanical properties along porcine thoracic aorta.

PubMed

Zeinali-Davarani, Shahrokh; Wang, Yunjie; Chow, Ming-Jay; Turcotte, Raphaël; Zhang, Yanhang

2015-05-01

As major extracellular matrix components, elastin, and collagen play crucial roles in regulating the mechanical properties of the aortic wall and, thus, the normal cardiovascular function. The mechanical properties of aorta, known to vary with age and multitude of diseases as well as the proximity to the heart, have been attributed to the variations in the content and architecture of wall constituents. This study is focused on the role of layer-specific collagen undulation in the variation of mechanical properties along the porcine descending thoracic aorta. Planar biaxial tensile tests are performed to characterize the hyperelastic anisotropic mechanical behavior of tissues dissected from four locations along the thoracic aorta. Multiphoton microscopy is used to image the associated regional microstructure. Exponential-based and recruitment-based constitutive models are used to account for the observed mechanical behavior while considering the aortic wall as a composite of two layers with independent properties. An elevated stiffness is observed in distal regions compared to proximal regions of thoracic aorta, consistent with sharper and earlier collagen recruitment estimated for medial and adventitial layers in the models. Multiphoton images further support our prediction that higher stiffness in distal regions is associated with less undulation in collagen fibers. Recruitment-based models further reveal that regardless of the location, collagen in the media is recruited from the onset of stretching, whereas adventitial collagen starts to engage with a delay. A parameter sensitivity analysis is performed to discriminate between the models in terms of the confidence in the estimated model parameters.

Persistent shoreline shape induced from offshore geologic framework: Effects of shoreface connected ridges

USGS Publications Warehouse

Safak, Ilgar; List, Jeffrey; Warner, John C.; Schwab, William C.

2017-01-01

Mechanisms relating offshore geologic framework to shoreline evolution are determined through geologic investigations, oceanographic deployments, and numerical modeling. Analysis of shoreline positions from the past 50 years along Fire Island, New York, a 50 km long barrier island, demonstrates a persistent undulating shape along the western half of the island. The shelf offshore of these persistent undulations is characterized with shoreface-connected sand ridges (SFCR) of a similar alongshore length scale, leading to a hypothesis that the ridges control the shoreline shape through the modification of flow. To evaluate this, a hydrodynamic model was configured to start with the US East Coast and scale down to resolve the Fire Island nearshore. The model was validated using observations along western Fire Island and buoy data, and used to compute waves, currents and sediment fluxes. To isolate the influence of the SFCR on the generation of the persistent shoreline shape, simulations were performed with a linearized nearshore bathymetry to remove alongshore transport gradients associated with shoreline shape. The model accurately predicts the scale and variation of the alongshore transport that would generate the persistent shoreline undulations. In one location, however, the ridge crest connects to the nearshore and leads to an offshore-directed transport that produces a difference in the shoreline shape. This qualitatively supports the hypothesized effect of cross-shore fluxes on coastal evolution. Alongshore flows in the nearshore during a representative storm are driven by wave breaking, vortex force, advection and pressure gradient, all of which are affected by the SFCR.

Morphology parameters for intracranial aneurysm rupture risk assessment.

PubMed

Dhar, Sujan; Tremmel, Markus; Mocco, J; Kim, Minsuok; Yamamoto, Junichi; Siddiqui, Adnan H; Hopkins, L Nelson; Meng, Hui

2008-08-01

The aim of this study is to identify image-based morphological parameters that correlate with human intracranial aneurysm (IA) rupture. For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured), three-dimensional geometries were evaluated for a range of morphological parameters. In addition to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity index, and undulation index), we defined three novel parameters incorporating the parent vessel geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed independent Student's t test for significance; significant parameters (P < 0.05) were further examined by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses were performed on each parameter. Statistically significant differences were found between mean values in ruptured and unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41; 95% confidence interval, 1.03-1.92) and undulation index (odds ratio, 1.51; 95% confidence interval, 1.08-2.11) had the strongest independent correlation with ruptured IA. From the receiver operating characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of 0.83 and 0.85, respectively. Size ratio and aneurysm angle are promising new morphological metrics for IA rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the gap between morphological studies and more qualitative location-based studies.

Thermal management and prototype testing of Compton scattering X-ray beam position monitor for the Advanced Photon Source Upgrade

DOE PAGES

Lee, S. H.; Yang, B. X.; Collins, J. T.; ...

2017-02-07

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs),more » which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This study presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.« less

The Latest Status of NSLS-II Insertion Devices

NASA Astrophysics Data System (ADS)

Tanabe, Toshi; Kitegi, Charles; He, Ping; Musardo, Marco; Rank, Oleg Chubar James; Cappadoro, Peter; Fernandes, Huston; Harder, David; Corwin, Todd

2014-03-01

The National Synchrotron Light Source-II (NSLS-II) project is now in the final stage of construction. The Linac, the Booster synchrotron, and the Storage Ring magnets girder assemblies have been installed. The first damping wiggler has been delivered and its field characteristics are carefully measured. A Three Pole Wiggler (3PW) and Apple-II type elliptically polarizing undulators (EPUs) have been fabricated by the vendors. Two 3.0m long in-vacuum undulators (IVUs) and one 1.5m long IVU are almost complete and waiting for factory acceptance tests. One 3.0m long IVU for Inelastic X-ray Scattering beamline is in fabrication by a different vendor. Recently two 2.8m long IVUs for long straight sections (LSSs) have been added to the project for "future beamlines". In addition, two 1.5m long IVUs and one 2.8m long IVU for LSSs have been procured for Advanced Beamlines for Biological Investigations with X-rays (ABBIX) project funded by National Institure of Health (NIH). Further, two 3.5m long EPUs for LSSs are being designed for NSLS-II Experimental Tools (NEXT) -Major Item of Equipment (MIE) project. To succeed these conventional IVUs, PrFeB based cryo-permanent magnet undulator (CPMU) is considered as next generation device of hard X-ray sources. An In-Vacuum Magnetic Measurement System (IVMMS) for cold in-situ Hall probe mapping of CPMUs up to 1.5m in length has been developed. Summary of the current status of each project and future plans for the NSLS-II ring will be discussed.

Toyota beamline (BL33XU) at SPring-8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nonaka, T., E-mail: nonaka@mosk.tytlabs.co.jp; Dohmae, K.; Hayashi, Y.

2016-07-27

The Toyota beamline (BL33XU) at SPring-8 is an undulator beamline developed to assist in the study of various automotive-related materials. The light source is a tapered in-vacuum undulator that provides a variable energy band width as well as a high brilliance X-ray beam. Two different optical arrangements are available: Optics 1 and Optics 2. Optics 1 is dedicated to time-resolved X-ray absorption spectroscopy (XAFS), and consists of two channel-cut crystal monochromators and four water-cooled flat Si mirrors. The Si(111) and Si(220) monochromator crystals cover an energy range of 4.0–46.0 keV and are driven by high-speed AC servo motors. These monochromators,more » in conjunction with the tapered undulator, enable high-quality XAFS data acquisition with a temporal resolution of 10 ms. Optics 2 is optimized for X-ray diffraction, scattering and imaging and includes a recently installed double crystal monochromator, two water-cooled flat Si mirrors and Kirkpatrick-Baez (KB) focusing mirrors. The monochromator incorporates parallel mounted Si(111) and Si(311) crystals and covers an energy range of 4.5–70 keV. The beamline provides two experimental stations: Exp. Hutch 2 and Exp. Hutch 3. The gas supply system and mass spectrometers installed in Exp. Hutch 2 allow in-operando measurements under various atmospheres. The scanning three-dimensional X-ray diffraction (scanning 3DXRD) microscopy instrumentation developed and installed in Exp. Hutch 3 enables non-destructive orientation and stress mapping of 1 mm-thick steel specimens using a high energy microbeam.« less

Why arboreal snakes should not be cylindrical: body shape, incline and surface roughness have interactive effects on locomotion.

PubMed

Jayne, Bruce C; Newman, Steven J; Zentkovich, Michele M; Berns, H Matthew

2015-12-01

Depending on animal size, shape, body plan and behaviour, variation in surface structure can affect the speed and ease of locomotion. The slope of branches and the roughness of bark both vary considerably, but their combined effects on the locomotion of arboreal animals are poorly understood. We used artificial branches with five inclines and five peg heights (≤40 mm) to test for interactive effects on the locomotion of three snake species with different body shapes. Unlike boa constrictors (Boa constrictor), corn snakes (Pantherophis guttatus) and brown tree snakes (Boiga irregularis) can both form ventrolateral keels, which are most pronounced in B. irregularis. Increasing peg height up to 10 mm elicited more of the lateral undulatory behaviour (sliding contact without gripping) rather than the concertina behaviour (periodic static gripping) and increased the speed of lateral undulation. Increased incline: (1) elicited more concertina locomotion, (2) decreased speed and (3) increased the threshold peg height that elicited lateral undulation. Boiga irregularis was the fastest species, and it used lateral undulation on the most surfaces, including a vertical cylinder with pegs only 1 mm high. Overall, B. constrictor was the slowest and used the most concertina locomotion, but this species climbed steep, smooth surfaces faster than P. guttatus. Our results illustrate how morphology and two different aspects of habitat structure can have interactive effects on organismal performance and behaviour. Notably, a sharper keel facilitated exploiting shorter protrusions to prevent slipping and provide propulsion, which became increasingly important as surface steepness increased. © 2015. Published by The Company of Biologists Ltd.

Experimental characterization of the saturating, near infrared, self-amplified spontaneous emission free electron laser: Analysis of radiation properties and electron beam dynamics

NASA Astrophysics Data System (ADS)

Murokh, Alex

2002-01-01

In this work, the main results of the VISA experiment (Visible to Infrared SASE Amplifier) are presented and analyzed. The purpose of the experiment was to build a state-of-the-art single pass self-amplified spontaneous emission (SASE) free electron laser (FEL) based on a high brightness electron beam, and characterize its operation, including saturation, in the near infrared spectral region. This experiment was hosted by Accelerator Test Facility (ATF) at Brookhaven National Laboratory, which is a users facility that provides high brightness relativistic electron beams generated with the photoinjector. During the experiment, SASE FEL performance was studied in two regimes: a long bunch, lower gain operation; and a short bunch high gain regime. The transition between the two conditions was possible due to a novel bunch compression mechanism, which was discovered in the course of the experiment. This compression allowed the variation of peak current in the electron beam before it was launched into the 4-m VISA undulator. In the long bunch regime, a SASE FEL power gain length of 29 cm was obtained, and the generated radiation spectral and statistical properties were characterized. In the short bunch regime, a power gain length of under 18 cm was achieved at 842 nm, which is at least a factor of two shorter than ever previously achieved in this spectral range. Further, FEL saturation was obtained before the undulator exit. The FEL system's performance was measured along the length of the VISA undulator, and in the final state. Statistical, spectral and angular properties of the short bunch SASE radiation have been measured in the exponential gain regime, and at saturation. One of the most important aspects of the data analysis presented in this thesis was the development and use of start-to-end numerical simulations of the experiment. The dynamics of the ATF electron beam was modeled starting from the photocathode, through acceleration, transport, and inside the VISA undulator. The model allowed simulation of SASE process for different beam conditions, including the effects of the novel bunch compression mechanism on the electron beam 6-D phase space distribution. The numerical simulations displayed an excellent agreement with the experimental data, and became key to understanding complex dynamics of the SASE FEL process at VISA.

Comparison of Powerlifting Performance in Trained Men Using Traditional and Flexible Daily Undulating Periodization.

PubMed

Colquhoun, Ryan J; Gai, Christopher M; Walters, Jeoffrey; Brannon, Andrew R; Kilpatrick, Marcus W; DʼAgostino, Dominic P; Campbell, Bill I

2017-02-01

Colquhoun, RJ, Gai, CM, Walters, J, Brannon, AR, Kilpatrick, MW, D'Agostino, DP, and Campbell, WI. Comparison of powerlifting performance in trained men using traditional and flexible daily undulating periodization. J Strength Cond Res 31(2): 283-291, 2017-Daily undulating periodization (DUP) is a growing trend, both in practice and in the scientific literature. A new form of DUP, flexible daily undulating periodization (FDUP), allows for athletes to have some autonomy by choosing the order of their training. The purpose of this study was to compare an FDUP model to a traditional model of DUP on powerlifting performance in resistance-trained men. Twenty-five resistance-trained men were randomly assigned to one of 2 groups: FDUP (N = 14) or DUP (N = 11). All participants possessed a minimum of 6 months of resistance training experience and were required to squat, bench press, and deadlift 125, 100, and 150% of their body mass, respectively. Dependent variables assessed at baseline and after the 9-week training program included bench press 1 repetition maximum (1RM), squat 1RM, deadlift 1RM, powerlifting total, Wilks Coefficient, fat mass, and fat-free mass (FFM). Dependent variables assessed during each individual training session were motivation to train, Session Rating of Perceived Exertion (Session RPE), and satisfaction with training session. After the 9-week training program, no significant differences in intensity or volume were found between groups. Both groups significantly improved bench press 1RM (FDUP: +6.5 kg; DUP: +8.8 kg), squat 1RM (FDUP: +15.6 kg; DUP: +18.0 kg), deadlift 1RM (FDUP: +14.8 kg; DUP: +13.6 kg), powerlifting total (FDUP: +36.8 kg; DUP: +40.4 kg), and Wilks Coefficient (FDUP: +24.8; DUP: +26.0) over the course of study (p = <0.001 for each variable). There was also a significant increase in FFM (FDUP: +0.8 kg; DUP: +0.8 kg) for both groups (p = 0.003). There were no differences in motivation to train, session RPE, or satisfaction with training session measurements between groups (p = 0.369-0.702, respectively). In conclusion, FDUP seems to offer similar resistance training adaptations when compared with a traditional DUP in resistance-trained men.

Laser-plasma interactions from thin tapes for high-energy electron accelerators and seeding compact FELs

NASA Astrophysics Data System (ADS)

Shaw, Brian Henry

This thesis comprises a detailed investigation of the physics of using a plasma mirror (PM) from a tape by reflecting ultrashort pulses from a laser-triggered surface plasma. The tapes used in the characterization of the PM are VHS and computer data storage tape. The tapes are 6.6 m (computer storage tape) and 15 m (VHS) thick. Each tape is 0.5 inches wide, and 10s of meters of tape are spooled using a tape drive; providing thousands of shots on a single reel of tape. The amount of reflected energy of the PM was studied for different input intensities. The fluence was varied by translating the focus of the laser upstream and downstream of the tape, which changed the spot size on the tape surface and hence changed the fluence. This study measured reflectances from both sides of the two tapes, and for input light of both s and p-polarizations. Lastly, an analytic model was developed to understand the reflectance as a function of fluence for each tape material and polarization. Another application that benefits from the advancements of LPA technology is an LPAbased FEL. By sending a high quality electron bunch through an undulator (a periodic structure of positive and negative magnetic poles), the electrons oscillate transversely to the propagation axis and produce radiation. The 1.5 m THUNDER undulator at the BELLA Center has been commissioned using electron beams of 400MeV beams with broad energy spread (35%). To produce a coherent LPA-based FEL, the beam quality would need to improve to sub-percent level energy spread. A seed source could be used to help induce bunching of the electron beam within the undulator. This thesis described the experimental investigation of the physics of using solid-based surface high-harmonic generation (SHHG) from a thin tape as a possible seed source for an FEL. A thin tape placed within centimeters of the undulator's entrance could act as a harmonic generating source, while simultaneously transmitting an electron beam. This removes the need for transport optics for the XUV photons and the need for additional optics to overlap the seed beam with the electron beam at the undulator entrance. By operating at sub-relativistic laser strengths, harmonics up to the 17th order of 800 nm light are produced using an SHHG technique known as coherent wake emission (CWE). CWE pulse properties such as divergence, energy, conversion efficiency, and spectrum are measured for a wide range of tape materials and drive laser conditions. A clear correlation between surface roughness and harmonic beam divergence is found. The measured pulse properties for the 15th harmonic from VHS tape (conversion efficiency 6.5x10-7 and an rms divergence of 12 mrad), the 100 mJ-level, 40-50 fs-class drive laser, produces peak powers of several MW's of XUV pulses. The results of a 1D model indicate that these CWE pulses with MW level powers are sufficient for seed-induced FEL gain. (Abstract shortened by ProQuest.).

Flow structure of knuckling effect in footballs

NASA Astrophysics Data System (ADS)

Asai, Takeshi; Kamemoto, Kyoji

2011-07-01

The flight trajectory of a non-spinning or slow-spinning soccer ball might fluctuate in unpredictable ways, as for example, in the many free kicks of C. Ronaldo. Such anomalous horizontal shaking or rapid falling is termed the ‘knuckling effect’. However, the aerodynamic properties and boundary-layer dynamics affecting a ball during the knuckling effect are not well understood. In this study, we analyse the characteristics of the vortex structure of a soccer ball subject to the knuckling effect (knuckleball), using high-speed video images and smoke-generating agents. Two high-speed video cameras were set at one side and in front of the ball trajectory between the ball position and the goal; further, photographs were taken at 1000 fps and a resolution of 1024×512 pixels. Although in a previous study (Taneda, 1978), shedding of horseshoe vortices was observed for smooth spheres in the Reynolds number (Re) range of 3.8×105

Kinematics, muscular activity and propulsion in gopher snakes

PubMed

Moon; Gans

1998-10-01

Previous studies have addressed the physical principles and muscular activity patterns underlying terrestrial lateral undulation in snakes, but not the mechanism by which muscular activity produces curvature and propulsion. In this study, we used synchronized electromyography and videography to examine the muscular basis and propulsive mechanism of terrestrial lateral undulation in gopher snakes Pituophis melanoleucus affinis. Specifically, we used patch electrodes to record from the semispinalis, longissimus dorsi and iliocostalis muscles in snakes pushing against one or more pegs. Axial bends propagate posteriorly along the body and contact the pegs at or immediately posterior to an inflection of curvature, which then reverses anterior to the peg. The vertebral column bends broadly around a peg, whereas the body wall bends sharply and asymmetrically around the anterior surface of the peg. The epaxial muscles are always active contralateral to the point of contact with a peg; they are activated slightly before or at the point of maximal convexity and deactivated variably between the inflection point and the point of maximal concavity. This pattern is consistent with muscular shortening and the production of axial bends, although variability in the pattern indicates that other muscles may affect the mechanics of the epaxial muscles. The kinematic and motor patterns in snakes crawling against experimentally increased drag indicated that forces are produced largely by muscles that are active in the axial bend around each peg, rather than by distant muscles from which the forces might be transmitted by connective tissues. At each point of force exertion, the propulsive mechanism of terrestrial lateral undulation may be modeled as a type of cam-follower, in which continuous bending of the trunk around the peg produces translation of the snake.

Formation events of shoreline sand waves on a gravel beach

NASA Astrophysics Data System (ADS)

Arriaga, Jaime; Falqués, Albert; Ribas, Francesca; Crews, Eddie

2018-06-01

Kilometric-scale shoreline sand waves (KSSW) have been observed in the north-east flank of the Dungeness Cuspate Foreland (southeastern coast of the UK). They consist of two bumps separated by embayments with a 350-450-m spacing. We have analysed 36 shoreline surveys of 2-km length using the Discrete Fourier Transformation (DFT), from 2005 to 2016, and seven topographic surveys encompassing the intertidal zone, from 2010 to 2016. The data set shows two clear formation events. In order to test the role of high-angle waves on the KSSW formation, the 10-year wave series is propagated from the wave buoy located at 43 m depth up to a location in front of the undulations at 4 m depth using the SWAN wave model. The dominating SW waves arrive with a very high incidence angle (˜ 80°) while the NE waves arrive almost shore normal. The ratio R, which measures the degree of dominance of high-angle waves with respect to low-angle waves, correlates well with the shoreline DFT magnitude values of the observed wavelength undulations. In particular, the highest R values coincide with the formation events. Finally, a linear stability model based on the one-line approximation is applied to the Dungeness profile and the 10-year propagated wave series. It predicts accurately the formation moments, with positive growth rates in the correct order of magnitude for wavelengths similar to the observed ones. All these results confirm that the shoreline undulations in Dungeness are self-organized and that the underlying formation mechanism is the high-angle wave instability. The two detected formation events provide a unique opportunity to validate the existing morphodynamic models that include such instability.

Hard X-ray Sources for the Mexican Synchrotron Project

NASA Astrophysics Data System (ADS)

Reyes-Herrera, Juan

2016-10-01

One of the principal tasks for the design of the Mexican synchrotron was to define the storage ring energy. The main criteria for choosing the energy come from studying the electromagnetic spectrum that can be obtained from the synchrotron, because the energy range of the spectrum that can be obtained will determine the applications available to the users of the future light source. Since there is a public demand of hard X-rays for the experiments in the synchrotron community users from Mexico, in this work we studied the emission spectra from some hard X-ray sources which could be the best options for the parameters of the present Mexican synchrotron design. The calculations of the flux and the brightness for one Bending Magnet and four Insertion Devices are presented; specifically, for a Superconducting Bending Magnet (SBM), a Superconducting Wiggler (SCW), an In Vacuum Short Period Undulator (IV-SPU), a Superconducting Undulator (SCU) and for a Cryogenic Permanent Magnet Undulator (CPMU). Two commonly available synchrotron radiation programs were used for the computation (XOP and SRW). From the results, it can be concluded that the particle beam energy from the current design is enough to have one or more sources of hard X-rays. Furthermore, a wide range of hard X-ray region can be covered by the analyzed sources, and the choice of each type should be based on the specific characteristics of the X-ray beam to perform the experiments at the involved beamline. This work was done within the project Fomix Conacyt-Morelos ”Plan Estrategico para la construccion y operación de un Sincrotron en Morelos” (224392).

New Strategic Plan Takes the ALS into the Future

NASA Astrophysics Data System (ADS)

Kirz, J.; Chemla, D. S.; Feinberg, B.; Hussain, Z.; Krebs, G. F.; Padmore, H. A.; Robin, D. S.; Robinson, A. L.; Smith, N. V.; Warwick, T.

2007-01-01

A new strategic plan is in place to upgrade the ALS so it can continue to address fundamental questions, such as size-dependent and dimensional-confinement phenomena at the nanoscale; correlation and complexity in physical, biological, and environmental systems; and temporal evolution, assembly, dynamics and ultrafast phenomena. Moreover, the growing number of ALS users (now exceeding 2,000 per year) requires increased attention. Accordingly, our plan concentrates on projects that will continue to make it possible for ALS users to address grand scientific and technological challenges with incisive world-class tools and quality user support. Our highest priority is to begin top-off operation, in which electrons are injected into the storage ring at intervals of approximately 1 minute. The combination of top-off and concurrent development of small-gap in-vacuum undulators and superconducting undulators will allow an increase in brightness from eight to more than 100 times, depending on the specific undulators and photon energy range. As part of our core mission in the VUV and soft x-ray regions, we plan to exploit these accelerator developments to extend our capabilities for high spatial and temporal resolution and utilize the remarkable coherence properties of the ALS in a new generation of beamlines. Ranked by priority, several proposed beamlines will follow completion of five new beamlines already under construction or funded. The intellectual excitement of the ALS has been a powerful tool in the recruitment and retention of outstanding staff, but additional sustained efforts are required to increase diversity both in gender and in underrepresented groups. To this end, we intend to expand the ALS Doctoral Fellowship Program by giving special emphasis to underrepresented groups. We also envision a distinguished postdoctoral fellowship program with the same emphasis, to increase and diversify our pool of candidates for beamline scientist positions.

Formation events of shoreline sand waves on a gravel beach

NASA Astrophysics Data System (ADS)

Arriaga, Jaime; Falqués, Albert; Ribas, Francesca; Crews, Eddie

2018-05-01

Kilometric-scale shoreline sand waves (KSSW) have been observed in the north-east flank of the Dungeness Cuspate Foreland (southeastern coast of the UK). They consist of two bumps separated by embayments with a 350-450-m spacing. We have analysed 36 shoreline surveys of 2-km length using the Discrete Fourier Transformation (DFT), from 2005 to 2016, and seven topographic surveys encompassing the intertidal zone, from 2010 to 2016. The data set shows two clear formation events. In order to test the role of high-angle waves on the KSSW formation, the 10-year wave series is propagated from the wave buoy located at 43 m depth up to a location in front of the undulations at 4 m depth using the SWAN wave model. The dominating SW waves arrive with a very high incidence angle (˜ 80°) while the NE waves arrive almost shore normal. The ratio R, which measures the degree of dominance of high-angle waves with respect to low-angle waves, correlates well with the shoreline DFT magnitude values of the observed wavelength undulations. In particular, the highest R values coincide with the formation events. Finally, a linear stability model based on the one-line approximation is applied to the Dungeness profile and the 10-year propagated wave series. It predicts accurately the formation moments, with positive growth rates in the correct order of magnitude for wavelengths similar to the observed ones. All these results confirm that the shoreline undulations in Dungeness are self-organized and that the underlying formation mechanism is the high-angle wave instability. The two detected formation events provide a unique opportunity to validate the existing morphodynamic models that include such instability.

Evaluation of GOCE-based global gravity field models over Japan after the full mission using free-air gravity anomalies and geoid undulations

NASA Astrophysics Data System (ADS)

Odera, Patroba Achola; Fukuda, Yoichi

2017-09-01

The performance of Gravity field and steady-state Ocean Circulation Explorer (GOCE) global gravity field models (GGMs), at the end of GOCE mission covering 42 months, is evaluated using geoid undulations and free-air gravity anomalies over Japan, including six sub-regions (Hokkaido, north Honshu, central Honshu, west Honshu, Shikoku and Kyushu). Seventeen GOCE-based GGMs are evaluated and compared with EGM2008. The evaluations are carried out at 150, 180, 210, 240 and 270 spherical harmonics degrees. Results show that EGM2008 performs better than GOCE and related GGMs in Japan and three sub-regions (Hokkaido, central Honshu and Kyushu). However, GOCE and related GGMs perform better than EGM2008 in north Honshu, west Honshu and Shikoku up to degree 240. This means that GOCE data can improve geoid model over half of Japan. The improvement is only evident between degrees 150 and 240 beyond which EGM2008 performs better than GOCE GGMs in all the six regions. In general, the latest GOCE GGMs (releases 4 and 5) perform better than the earlier GOCE GGMs (releases 1, 2 and 3), indicating the contribution of data collected by GOCE in the last months before the mission ended on 11 November 2013. The results indicate that a more accurate geoid model over Japan is achievable, based on a combination of GOCE, EGM2008 and terrestrial gravity data sets. [Figure not available: see fulltext. Caption: Standard deviations of the differences between observed and GGMs implied ( a) free-air gravity anomalies over Japan, ( b) geoid undulations over Japan. n represents the spherical harmonic degrees

First results from the commissioning of the FERMI@Elettra free electron laser by means of the Photon Analysis Delivery and Reduction System (PADReS)

NASA Astrophysics Data System (ADS)

Zangrando, M.; Cudin, I.; Fava, C.; Gerusina, S.; Gobessi, R.; Godnig, R.; Rumiz, L.; Svetina, C.; Parmigiani, F.; Cocco, D.

2011-06-01

The Italian Free Electron Laser (FEL) facility FERMI@Elettra has started to produce photon radiation at the end of 2010. The photon beam is presently delivered by the first undulator chain (FEL1) that is supposed to produce photons in the 100-20 nm wavelength range. A second undulator chain (FEL2) will be commissioned at the end of 2011, and it will produce radiation in the 20-4nm range. The Photon Analysis Delivery and Reduction System (PADReS) was designed to collect the radiation coming from both the undulator chains (FEL1 and FEL2), to characterize and control it, and to redirect it towards the following beamlines. The first parameters that are checked are the pulse-resolved intensity and beam position. For each of these parameters two dedicated monitors are installed along PADReS on each FEL line. In this way it possible to determine the intensity reduction that is realized by the gas reduction system, which is capable of cutting the intensity by up to four orders of magnitude. The energy distribution of each single pulse is characterized by an online spectrometer installed in the experimental hall. Taking advantage of a variable line-spacing grating it can direct the almost-full beam to the beamlines, while it uses a small fraction of the beam itself to determine the spectral distribution of each pulse delivered by the FEL. The first light of FERMI@Elettra, delivered to the PADReS section in late 2010, is used for the first commissioning runs and some preliminary experiments whose results are reported and discussed in detail.

Robert R. Wilson Prize: The Quest for Bright, Coherent X-Rays: A Personal Story

NASA Astrophysics Data System (ADS)

Kim, Kwang Je

2014-03-01

Stories associated with the advances in x-ray source techniques during the last several decades will be told from a personal viewpoint. I will start from the ``third-generation'' x-ray sources based on storage-ring-based undulators and a struggle to find a proper way to quantify the radiation strength. I will then discuss how the initially incoherent undulator radiation evolves into an intense-quasi-coherent radiation via free-electron laser (FEL) interaction. This so-called self-amplified spontaneous emission (SASE) in the x-ray region could be realized with the advent of laser-induced electron guns and forms the basis of the linac-driven ``fourth generation'' x-ray facilities. An x-ray FEL oscillator (XFELO) will also be feasible if Bragg reflectors, such as diamond crystals, are used as cavity mirrors. An XFELO driven by a CW superconducting linac would be a ``real x-ray laser,'' producing a steady stream of fully coherent, spectrally pure x-ray pulses. An XFELO can be mode-locked, thus producing x-ray spectral comb, if the cavity length can be fixed to a fraction of the x-ray wavelength by referencing to a narrow nuclear resonance. A mode-locked XFELO will enable x-ray quantum optics experiments, such as matter-wave interferometry, for fundamental physics. Alongside these main themes, stories for novel and ``cute'' schemes, such as a crossed undulator for polarization switching and an emittance exchanger for swapping the transverse and longitudinal phase space, will also be presented. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.

New Strategic Plan Takes the ALS into the Future

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirz, J.; Chemla, D.S.; Feinberg, B.

2006-08-12

A new strategic plan is in place to upgrade the ALS so itcan continue to address fundamental questions, such as size-dependent anddimensional-confinement phenomena at the nanoscale; correlation andcomplexity in physical, biological, and environmental systems; andtemporal evolution, assembly, dynamics and ultrafast phenomena. Moreover,the growing number of ALS users (now exceeding 2,000 per year) requiresincreased attention. Accordingly, our plan concentrates on projects thatwill continue to make it possible for ALS users to address grandscientific and technological challenges with incisive world-class toolsand quality user support. Our highest priority is to begin top-offoperation, in which electrons are injected into the storage ring atintervals ofmore » approximately 1 minute. The combination of top-off andconcurrent development of small-gap in-vacuum undulators andsuperconducting undulators will allow an increase in brightness fromeight to more than 100 times, depending on the specific undulators andphoton energy range. As part of our core mission in the VUV and softx-ray regions, we plan to exploit these accelerator developments toextend our capabilities for high spatial and temporal resolution andutilize the remarkable coherence properties of the ALS in a newgeneration of beamlines. Ranked by priority, several proposed beamlineswill follow completion of five new beamlines already under constructionor funded. The intellectual excitement of the ALS has been a powerfultool in the recruitment and retention of outstanding staff, butadditional sustained efforts are required to increase diversity both ingender and in underrepresented groups. To this end, we intend to expandthe ALS Doctoral Fellowship Program by giving special emphasis tounderrepresented groups. We also envision a distinguished postdoctoralfellowship program with the same emphasis, to increase and diversify ourpool of candidates for beamline scientist positions.« less

Space-borne observation of mesospheric bore by Visible and near Infrared Spectral Imager onboard the International Space Station

NASA Astrophysics Data System (ADS)

Hozumi, Y.; Saito, A.; Sakanoi, T.; Yamazaki, A.; Hosokawa, K.

2017-12-01

Mesospheric bores were observed by Visible and near Infrared Spectral Imager (VISI) of the ISS-IMAP mission (Ionosphere, Mesosphere, upper Atmosphere and Plasmasphere mapping mission from the International Space Station) in O2 airglow at 762 nm wavelength. The mesospheric bore is moving front of sharp jump followed by undulations or turbulence in the mesopause region. Since previous studies of mesospheric bore were mainly based on ground-based airglow imaging that is limited in field-of-view and observing site, little is known about its horizontal extent and global behavior. Space-borne imaging by ISS-IMAP/VISI provides an opportunity to study the mesospheric bore with a wide field-of-view and global coverage. A mesospheric bore was captured by VISI in two consecutive paths on 9 July 2015 over the south of African continent (48ºS - 54ºS and 15ºE). The wave front aligned with south-north direction and propagated to west. The phase velocity and wave length of the following undulation were estimated to 100 m/s and 30 km, respectively. Those parameters are similar to those reported by previous studies. 30º anti-clockwise rotation of the wave front was recognized in 100 min. Another mesospheric bore was captured on 9 May 2013 over the south Atlantic ocean (35ºS - 43ºS and 24ºW - 1ºE) with more than 2,200 km horizontal extent of wave front. The wave front aligned with southeast-northwest direction. Because the following undulation is recognized in the southwest side of the wave front, it is estimated to propagate to northeast direction. The wave front was modulated with 1,000 km wave length. This modulation implies inhomogeneity of the phase velocity.

Comparison between linear and daily undulating periodized resistance training to increase strength.

PubMed

Prestes, Jonato; Frollini, Anelena B; de Lima, Cristiane; Donatto, Felipe F; Foschini, Denis; de Cássia Marqueti, Rita; Figueira, Aylton; Fleck, Steven J

2009-12-01

To determine the most effective periodization model for strength and hypertrophy is an important step for strength and conditioning professionals. The aim of this study was to compare the effects of linear (LP) and daily undulating periodized (DUP) resistance training on body composition and maximal strength levels. Forty men aged 21.5 +/- 8.3 and with a minimum 1-year strength training experience were assigned to an LP (n = 20) or DUP group (n = 20). Subjects were tested for maximal strength in bench press, leg press 45 degrees, and arm curl (1 repetition maximum [RM]) at baseline (T1), after 8 weeks (T2), and after 12 weeks of training (T3). Increases of 18.2 and 25.08% in bench press 1 RM were observed for LP and DUP groups in T3 compared with T1, respectively (p < or = 0.05). In leg press 45 degrees , LP group exhibited an increase of 24.71% and DUP of 40.61% at T3 compared with T1. Additionally, DUP showed an increase of 12.23% at T2 compared with T1 and 25.48% at T3 compared with T2. For the arm curl exercise, LP group increased 14.15% and DUP 23.53% at T3 when compared with T1. An increase of 20% was also found at T2 when compared with T1, for DUP. Although the DUP group increased strength the most in all exercises, no statistical differences were found between groups. In conclusion, undulating periodized strength training induced higher increases in maximal strength than the linear model in strength-trained men. For maximizing strength increases, daily intensity and volume variations were more effective than weekly variations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesgin, Ibrahim; Hasse, Quentin; Ivanyushenkov, Yury

The use of second-generation high-temperature superconducting-coated conductors enables an enhancement of the performance of undulator magnets. However, preventing the motion of the wire and providing sufficient conduction cooling to the winding stacks have remained challenges. In this study, we have evaluated epoxy impregnation techniques to address these issues. Epoxy resin was prepared with different nanopowders and the effect on the performance of the undulator coil pack was investigated. All epoxy impregnated coils showed smaller n values and some degree of deterioration of the critical current I c. The I c degradation was most pronounced for epoxy mixed with high aspectmore » ratio multiwalled carbon nanotubes (MWCNTs). It has been found that the crack formation in the epoxy results in plastic deformation of the copper stabilizer layer, which causes the underlying ceramic REBCO superconducting layer to crack resulting in degradation of the superconducting tape performance. As a result, careful adjustment of epoxy thickness surrounding the superconductor and the powder ratio in the epoxy eliminate the performance degradation.« less

Undulated Nozzle for Enhanced Exit Area Mixing

NASA Technical Reports Server (NTRS)

Seiner, John M. (Inventor); Gilinsky, Mikhail M. (Inventor)

2000-01-01

A nozzle having an undulating surface for enhancing the mixing of a primary flow with a secondary flow or ambient air, without requiring an ejector. The nozzle includes a nozzle structure and design for introducing counter-rotating vorticity into the primary flow either through (i) internal surface corrugations where an axisymmetric line through each corrugation is coincident with an axisymmetric line through the center of the flow passageway or (ii) through one or more sets of alternating convexities and cavities in the internal surface of the nozzle where an axisymmetric line through each convexity and cavity is coincident with an axisymmetric line through the center of the flow passageway, and where the convexities contract from the entrance end towards the exit end. Exit area mixing is also enhanced by one or more chevrons attached to the exit edge of the nozzle. The nozzle is ideally suited for application as a jet engine nozzle. When used as a jet engine nozzle, noise suppression with simultaneous thrust augmentation/minimal thrust loss is achieved.

Convergent evolution of mechanically optimal locomotion in aquatic invertebrates and vertebrates.

PubMed

Bale, Rahul; Neveln, Izaak D; Bhalla, Amneet Pal Singh; MacIver, Malcolm A; Patankar, Neelesh A

2015-04-01

Examples of animals evolving similar traits despite the absence of that trait in the last common ancestor, such as the wing and camera-type lens eye in vertebrates and invertebrates, are called cases of convergent evolution. Instances of convergent evolution of locomotory patterns that quantitatively agree with the mechanically optimal solution are very rare. Here, we show that, with respect to a very diverse group of aquatic animals, a mechanically optimal method of swimming with elongated fins has evolved independently at least eight times in both vertebrate and invertebrate swimmers across three different phyla. Specifically, if we take the length of an undulation along an animal's fin during swimming and divide it by the mean amplitude of undulations along the fin length, the result is consistently around twenty. We call this value the optimal specific wavelength (OSW). We show that the OSW maximizes the force generated by the body, which also maximizes swimming speed. We hypothesize a mechanical basis for this optimality and suggest reasons for its repeated emergence through evolution.

Construction and performance of BL28 of the Photon Factory for circularly polarized synchrotron radiation

NASA Astrophysics Data System (ADS)

Kagoshima, Yasushi; Muto, Sadatsugu; Miyahara, Tsuneaki; Koide, Tsuneharu; Yamamoto, Shigeru; Kitamura, Hideo

1992-01-01

A branch beamline, BL28A, has been constructed for the application of circularly polarized vacuum ultraviolet radiation. The radiation can be obtained in the helical undulator operation mode of an insertion device, EMPW♯28, which is also cut for elliptically polarized hard x-ray radiation. T first harmonic of the helical undulator radiation can be tuned from 40 to 350 eV with its corresponding K value from 3 to 0.2. A monochromator working basically with constant deviation optics was installed, and has started its operation. A circularly polarized flux of ˜1010 photons/s has been achieved with energy resolution of around 500-1000 at the first harmonic peak. The circular polarization after the monochromator was estimated to be higher than 70% by comparing theory and experiment on the magnetic circular dichroism of nickel films in the 3p-3d excitation region. The design philosophy of the beamline and recent results on the performance tests are presented.

Microbunching-instability-induced sidebands in a seeded free-electron laser

DOE PAGES

Zhang, Zhen; Lindberg, Ryan; Fawley, William M.; ...

2016-05-02

Measurements of the multishot-averaged, soft x-ray, self-seeding spectrum at the LCLS free-electron laser often have a pedestal-like distribution around the seeded wavelength, which limits the spectral purity and can negatively affect some user applications not employing a post-undulator monochromator. In this paper, we study the origins of such pedestals, focusing on longitudinal phase space modulations produced by the microbunching instability upstream of the free-electron laser (FEL) undulator. Furthermore, we show from theory and numerical simulation that both energy and density modulations can induce sidebands in a high-gain, seeded FEL whose fractional strength typically grows as the square of the undulatormore » length. The results place a tight constraint on the longitudinal phase space uniformity of the electron beam for a seeded FEL, possibly requiring the amplitude of long-wavelength modulations to be much smaller than the typical incoherent energy spread if the output sideband power is to remain only a couple percent or less of the amplified seed power.« less

A compact tunable polarized X-ray source based on laser-plasma helical undulators

PubMed Central

Luo, J.; Chen, M.; Zeng, M.; Vieira, J.; Yu, L. L.; Weng, S. M.; Silva, L. O.; Jaroszynski, D. A.; Sheng, Z. M.; Zhang, J.

2016-01-01

Laser wakefield accelerators have great potential as the basis for next generation compact radiation sources because of their extremely high accelerating gradients. However, X-ray radiation from such devices still lacks tunability, especially of the intensity and polarization distributions. Here we propose a tunable polarized radiation source based on a helical plasma undulator in a plasma channel guided wakefield accelerator. When a laser pulse is initially incident with a skew angle relative to the channel axis, the laser and accelerated electrons experience collective spiral motions, which leads to elliptically polarized synchrotron-like radiation with flexible tunability on radiation intensity, spectra and polarization. We demonstrate that a radiation source with millimeter size and peak brilliance of 2 × 1019 photons/s/mm2/mrad2/0.1% bandwidth can be made with moderate laser and electron beam parameters. This brilliance is comparable with third generation synchrotron radiation facilities running at similar photon energies, suggesting that laser plasma based radiation sources are promising for advanced applications. PMID:27377126

Strain relaxation induced surface morphology of heterogeneous GaInNAs layers grown on GaAs substrate

NASA Astrophysics Data System (ADS)

Gelczuk, Ł.; Jóźwiak, G.; Moczała, M.; Dłużewski, P.; Dąbrowska-Szata, M.; Gotszalk, T. P.

2017-07-01

The partially-relaxed heterogeneous GaInNAs layers grown on GaAs substrate by atmospheric pressure vapor phase epitaxy (AP-MOVPE) were investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The planar-view TEM image shows a regular 2D network of misfit dislocations oriented in two orthogonal 〈1 1 0〉 crystallographic directions at the (0 0 1) layer interface. Moreover, the cross-sectional view TEM image reveals InAs-rich and V-shaped precipitates in the near surface region of the GaInNAs epitaxial layer. The resultant undulating surface morphology, known as a cross-hatch pattern, is formed as observed by AFM. The numerical analysis of the AFM image of the GaInNAs layer surface with the well-defined cross-hatch morphology enabled us to determine a lower bound of actual density of misfit dislocations. However, a close correspondence between the asymmetric distribution of interfacial misfit dislocations and undulating surface morphology is observed.

Time-dependent multi-dimensional simulation studies of the electron output scheme for high power FELs

NASA Astrophysics Data System (ADS)

Hahn, S. J.; Fawley, W. M.; Kim, K. J.; Edighoffer, J. A.

1994-12-01

The authors examine the performance of the so-called electron output scheme recently proposed by the Novosibirsk group. In this scheme, the key role of the FEL oscillator is to induce bunching, while an external undulator, called the radiator, then outcouples the bunched electron beam to optical energy via coherent emission. The level of the intracavity power in the oscillator is kept low by employing a transverse optical klystron (TOK) configuration, thus avoiding excessive thermal loading on the cavity mirrors. Time-dependent effects are important in the operation of the electron output scheme because high gain in the TOK oscillator leads to sideband instabilities and chaotic behavior. The authors have carried out an extensive simulation study by using 1D and 2D time-dependent codes and find that proper control of the oscillator cavity detuning and cavity loss results in high output bunching with a narrow spectral bandwidth. Large cavity detuning in the oscillator and tapering of the radiator undulator is necessary for the optimum output power.

Development of Mini-pole Superconducting Undulator

NASA Astrophysics Data System (ADS)

Jan, J. C.; Hwang, C. S.; Lin, P. H.; Chang, C. H.; Lin, F. Y.

2007-01-01

A mini-pole superconducting undulator with a 15mm period length (SU15) was developed at the National Synchrotron Radiation Research Center (NSRRC). The coil was wound by a superconducting (SC) NbTi wire with small dimensions and low Cu/SC ratio. The design field strength of SU15 with 158turns/pole was 1.4T at 215A, and the magnet gap was 5.6 mm. Extra trim coils and poles are mounted on the main iron pole. The trim coils directly compensate for the strength error of the peak field. The prototype racetrack iron pole was fabricated via electric discharge machining to produce a complete set of 40-poles. The coil was impregnated by epoxy and wrapped in Kapton to maintain insulation between coil and iron pole. A substitution beam duct was built and assembled with the magnet array and tested in the test Dewar. The conceptual design of bath liquid helium (LHe) cryostat has to tolerate more image current and radiation heating on the beam duct.

Evaluation of bending modulus of lipid bilayers using undulation and orientation analysis

NASA Astrophysics Data System (ADS)

Chaurasia, Adarsh K.; Rukangu, Andrew M.; Philen, Michael K.; Seidel, Gary D.; Freeman, Eric C.

2018-03-01

In the current paper, phospholipid bilayers are modeled using coarse-grained molecular dynamics simulations with the MARTINI force field. The extracted molecular trajectories are analyzed using Fourier analysis of the undulations and orientation vectors to establish the differences between the two approaches for evaluating the bending modulus. The current work evaluates and extends the implementation of the Fourier analysis for molecular trajectories using a weighted horizon-based averaging approach. The effect of numerical parameters in the analysis of these trajectories is explored by conducting parametric studies. Computational modeling results are validated against experimentally characterized bending modulus of lipid membranes using a shape fluctuation analysis. The computational framework is then used to estimate the bending moduli for different types of lipids (phosphocholine, phosphoethanolamine, and phosphoglycerol). This work provides greater insight into the numerical aspects of evaluating the bilayer bending modulus, provides validation for the orientation analysis technique, and explores differences in bending moduli based on differences in the lipid nanostructures.

Effects of different set configurations on barbell velocity and displacement during a clean pull.

PubMed

Haff, G Gregory; Whitley, Adrian; McCoy, Lora B; O'Bryant, Harold S; Kilgore, J Lon; Haff, Erin E; Pierce, Kyle; Stone, Michael H

2003-02-01

The effects of 3 types of set configurations (cluster, traditional, and undulating) on barbell kinematics were investigated in the present study. Thirteen men (track and field = 8; Olympic weightlifters = 5) (mean +/- SEM age, 23.4 +/- 1.1 years; height, 181.3 +/- 2.1 cm; body mass, 89.8 +/- 4.2 kg) performed 1 set of 5 repetitions in a cluster, traditional, and undulating fashion at 90 and 120% of their 1 repetition maximum (1RM) power clean (119.0 +/- 4.3 kg). All data were collected at 50 Hz and analyzed with a V-Scope Weightlifting Analysis System. Peak velocity (PV) and peak displacement (PD) were analyzed for each repetition and averaged for each set type. Results indicated that a significantly (p < 0.016) higher PV occurred during the cluster set when compared with the traditional sets at both intensities. PD was significantly higher than traditional sets at the 120% intensity. The present study suggests set configuration can affect PV and PD during clean pulls.

Spermatozoon structure and motility in the anuran Lepidobatrachus laevis.

PubMed

Waggener, W L; Carroll, E J

1998-02-01

Synthetic human gonadotropin releasing hormone (GnRH) injections were used for induction of spermatozoon release followed by cloacal lavage or mechanical stimulation of sperm release in Lepidobatrachus laevis. Light microscopic observations of Lepidobatrachus laevis spermatozoa indicated an acrosomal segment with a length of 4.1 microm delineated by an indentation, a nuclear region of 12.6 microm in length and a midpiece of 0.87 microm in length. The tail was 54.9 microm long by 1.35 microm wide with two lateral axial fibers and a central undulating membrane. At the electron microscopic level, the unusual tail had two complete axonemes that emanated from the distal centriole. The tail also contained two axial fibers 77 nm in diameter medial to the axonemes and was connected by an undulating membrane. An unusual accessory cell adherent to the head of the spermatozoon was noted in freshly obtained suspensions of spermatozoa. Spermatozoa with the accessory cell were motile and a subsequent loss of motility was correlated with the shedding of the accessory cell.

ATTO SECOND ELECTRON BEAMS GENERATION AND CHARACTERIZATION EXPERIMENT AT THE ACCELERATOR TEST FACILITY.

DOE Office of Scientific and Technical Information (OSTI.GOV)

ZOLOTOREV, M.; ZHOLENTS, A.; WANG, X.J.

2002-02-01

We are proposing an Atto-second electron beam generation and diagnostics experiment at the Brookhaven Accelerator Test facility (ATF) using 1 {micro}m Inverse Free Electron Laser (IFEL). The proposed experiment will be carried out by an BNL/LBNL collaboration, and it will be installed at the ATF beam line II. The proposed experiment will employ a one-meter long undulator with 1.8 cm period (VISA undulator). The electron beam energy will be 63 MeV with emittance less than 2 mm-mrad and energy spread less than 0.05%. The ATF photocathode injector driving laser will be used for energy modulation by Inverse Free Electron Lasermore » (IFEL). With 10 MW laser peak power, about 2% total energy modulation is expected. The energy modulated electron beam will be further bunched through either a drift space or a three magnet chicane into atto-second electron bunches. The attosecond electron beam bunches will be analyzed using the coherent transition radiation (CTR).« less

Theory of multiwave mixing within the superconducting kinetic-inductance traveling-wave amplifier

NASA Astrophysics Data System (ADS)

Erickson, R. P.; Pappas, D. P.

2017-03-01

We present a theory of parametric mixing within the coplanar waveguide (CPW) of a superconducting nonlinear kinetic-inductance traveling-wave (KIT) amplifier engineered with periodic dispersion loadings. This is done by first developing a metamaterial band theory of the dispersion-engineered KIT using a Floquet-Bloch construction and then applying it to the description of mixing of the nonlinear RF traveling waves. Our theory allows us to calculate signal gain versus signal frequency in the presence of a frequency stop gap, based solely on loading design. We present results for both three-wave mixing (3WM), with applied dc bias, and four-wave mixing (4WM), without dc. Our theory predicts an intrinsic and deterministic origin to undulations of 4WM signal gain with signal frequency, apart from extrinsic sources, such as impedance mismatch, and shows that such undulations are absent from 3WM signal gain achievable with dc. Our theory is extensible to amplifiers based on Josephson junctions in a lumped LC-ladder transmission line (TWPA).

Gravity anomaly and geoid undulation results in local areas from GEOS-3 altimeter data

NASA Technical Reports Server (NTRS)

Rapp, R. H.

1979-01-01

The adjusted GEOS-3 altimeter data, taken as averages within a data frame, have been used to construct free air anomaly and geoid undulation profiles and maps in areas of geophysical interest. Profiles were constructed across the Philippine Trench (at a latitude of 6 deg) and across the Bonin Trench (at a latitude of 28 deg). In the latter case an anomaly variation of 443 mgals in 143 km was derived from the altimeter data. These variations agreed reasonably with terrestrial estimates, considering the predicted point accuracy was about + or - 27 mgals. An area over the Patton Sea mounts was also investigated with the altimeter anomaly field agreeing well with the terrestrial data except for the point directly over the top of the sea mount. It is concluded that the GEOS-3 altimeter data is valuable not only for determining 5 deg and 1 deg x 1 deg mean anomalies, but also can be used to describe more local anomaly variations.

The influence of the atmosphere on geoid and potential coefficient determinations from gravity data

NASA Technical Reports Server (NTRS)

Rummel, R.; Rapp, R. H.

1976-01-01

For the precise computation of geoid undulations the effect of the attraction of the atmosphere on the solution of the basic boundary value problem of gravimetric geodesy must be considered. This paper extends the theory of Moritz for deriving an atmospheric correction to the case when the undulations are computed by combining anomalies in a cap surrounding the computation point with information derived from potential coefficients. The correction term is a function of the cap size and the topography within the cap. It reaches a value of 3.0 m for a cap size of 30 deg, variations on the decimeter level being caused by variations in the topography. The effect of the atmospheric correction terms on potential coefficients is found to be small, reaching a maximum of 0.0055 millionths at n = 2, m = 2 when terrestrial gravity data are considered. The magnitude of this correction indicates that in future potential coefficient determination from gravity data the atmospheric correction should be made to such data.

MX2: a high-flux undulator microfocus beamline serving both the chemical and macromolecular crystallography communities at the Australian Synchrotron

PubMed Central

Aishima, Jun; Cherukuvada, Hima; Clarken, Robert; Clift, Mark; Ericsson, Daniel Jesper; Macedo, Sofia; Mudie, Nathan; Price, Jason Roy; Rostan, Robert; Williamson, Rachel

2018-01-01

MX2 is an in-vacuum undulator-based crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X-rays in the energy range 4.8–21 keV to a focal spot of 22 × 12 µm FWHM (H × V). At 13 keV the flux at the sample is 3.4 × 1012 photons s−1. The beamline endstation allows robotic handling of cryogenic samples via an updated SSRL SAM robot. This beamline is ideal for weakly diffracting hard-to-crystallize proteins, virus particles, protein assemblies and nucleic acids as well as smaller molecules such as inorganic catalysts and organic drug molecules. The beamline is now mature and has enjoyed a full user program for the last nine years. This paper describes the beamline status, plans for its future and some recent scientific highlights. PMID:29714201

Transequatorial Propagation and Depletion Precursors

NASA Astrophysics Data System (ADS)

Miller, E. S.; Bust, G. S.; Kaeppler, S. R.; Frissell, N. A.; Paxton, L. J.

2014-12-01

The bottomside equatorial ionosphere in the afternoon and evening sector frequently evolves rapidly from smoothly stratified to violently unstable with large wedges of depleted plasma growing through to the topside on timescales of a few tens of minutes. These depletions have numerous practical impacts on radio propagation, including amplitude scintillation, field-aligned irregularity scatter, HF blackouts, and long-distance transequatorial propagation at frequencies above the MUF. Practical impacts notwithstanding, the pathways and conditions under which depletions form remain a topic of vigorous inquiry some 80 years after their first report. Structuring of the pre-sunset ionosphere---morphology of the equatorial anomalies and long-wavelength undulations of the isodensity contours on the bottomside---are likely to hold some clues to conditions that are conducive to depletion formation. The Conjugate Depletion Experiment is an upcoming transequatorial forward-scatter HF/VHF experiment to investigate pre-sunset undulations and their connection with depletion formation. We will present initial results from the Conjugate Depletion Experiment, as well as a companion analysis of a massive HF propagation data set.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nuhn, Heinz-Dieter.

The Visual to Infrared SASE Amplifier (VISA) [1] FEL is designed to achieve saturation at radiation wavelengths between 800 and 600 nm with a 4-m pure permanent magnet undulator. The undulator comprises four 99-cm segments each of which has four FODO focusing cells superposed on the beam by means of permanent magnets in the gap alongside the beam. Each segment will also have two beam position monitors and two sets of x-y dipole correctors. The trajectory walk-off in each segment will be reduced to a value smaller than the rms beam radius by means of magnet sorting, precise fabrication, andmore » post-fabrication shimming and trim magnets. However, this leaves possible inter-segment alignment errors. A trajectory analysis code has been used in combination with the FRED3D [2] FEL code to simulate the effect of the shimming procedure and segment alignment errors on the electron beam trajectory and to determine the sensitivity of the FEL gain process to trajectory errors. The paper describes the technique used to establish tolerances for the segment alignment.« less

Hydrodynamic optimality of balistiform and gymnotiform locomotion

NASA Astrophysics Data System (ADS)

Sprinkle, Brennan; Bale, Rahul; Bhalla, Amneet Pal Singh; MacIver, Malcolm A.; Patankar, Neelesh A.

2017-03-01

Some groups of fish have evolved to generate propulsion using undulatory elongated fins while maintaining a relatively rigid body. The fins run along the body axis and can be dorsal, ventral, dorsoventral pairs or left-right pairs. These fish are termed as median/paired fin (MPF) swimmers. The movement of these groups of fish was studied in an influential series of papers by Lighthill and Blake. In this work, we revisit this problem by performing direct numerical simulations. We interrogate two issues. First, we investigate and explain a key morphological feature, which is the diagonal fin insertion found in many MPF swimmers such as the knifefish. Not only are these results of biological relevance, but these are also useful in engineering to design bioinspired highly maneuverable underwater vehicles. Second, we investigate whether there is a mechanical advantage in the form of reduced cost of transport (COT) (energy spent per unit distance traveled) for not undulating the entire body. We find that a rigid body attached to an undulating fin leads to a reduced COT.

Femtosecond synchronism of x-rays and visible/infrared light in an x-ray free-electron laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, B. W.

2007-12-15

A way is proposed to obtain ultrashort pulses of intense infrared/visible light in few-femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL). It makes use of the recently proposed emittance-slicing technique [Emma et al., Phys. Rev. Lett. 92, 074801 (2004)] to both restrict the duration of self-amplified spontaneous emission (SASE) to a few femtoseconds and to lead to a coherence enhancement of near-infrared transition undulator radiation (CTUR). The x-rays and the near-infrared light originate within the XFEL undulator from the same slice of electrons within a bunch and are therefore perfectly synchronized with each other. An example of realizingmore » the scheme at the Linac Coherent Light Source is presented. A few side issues are explored briefly, such as the magnitude of the velocity term versus the acceleration term in the Lienard-Wiechert fields and the possible use of the CTUR as a diagnostic tool for the SASE process itself.« less

Motility modes of the parasite Trypanosoma brucei

NASA Astrophysics Data System (ADS)

Temel, Fatma Zeynep; Qu, Zijie; McAllaster, Michael; de Graffenried, Christopher; Breuer, Kenneth

2015-11-01

The parasitic single-celled protozoan Trypanosoma brucei causes African Sleeping Sickness, which is a fatal disease in humans and animals that threatens more than 60 million people in 36 African countries. Cell motility plays a critical role in the developmental phases and dissemination of the parasite. Unlike many other motile cells such as bacteria Escherichia coli or Caulobacter crescentus, the flagellum of T. brucei is attached along the length of its awl-like body, producing a unique mode of motility that is not fully understood or characterized. Here, we report on the motility of T. brucei, which swims using its single flagellum employing both rotating and undulating propulsion modes. We tracked cells in real-time in three dimensions using fluorescent microscopy. Data obtained from experiments using both short-term tracking within the field of view and long-term tracking using a tracking microscope were analyzed. Motility modes and swimming speed were analyzed as functions of cell size, rotation rate and undulation pattern. Research supported by NSF.

Breaking the Attosecond, Angstrom and TV/M Field Barriers with Ultra-Fast Electron Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenzweig, James; Andonian, Gerard; Fukasawa, Atsushi

2012-06-22

Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This use of very low Q beams may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the LCLS have produced {approx}2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments in cryogenic undulator technology, to create compact accelerator-undulator systems that can lase belowmore » 0.15 {angstrom}, or be used to permit 1.5 {angstrom} operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications.« less

Radiological considerations in the operation of the low-energy undulator test line (LEUTL).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moe, H.J.

1998-11-11

The Low-Energy Undulator Test Line (LEUTL) is a facility that uses the existing APS linac to accelerate electrons up to an energy of 700 MeV. These electrons are transported through the Pm into a portion of the booster synchrotrons and on into the LEUTL main enclosure (MIL 97). Figure 1 shows the layout of the LEUTL building, which consists of an earth-benned concrete enclosure and an end-station building. The concrete enclosure houses the electron beamline, test undulator, and beam dump. This facility is about 51 m long and 3.66 m wide. Technical components and diagnostics for characterizing the undulator lightmore » are found in the end station. This building has about 111 m{sup 2} of floor space. This note deals with the radiological considerations of operations using electrons up to 700 MeV and at power levels up to the safety envelope of 1 kW. Previous radiological considerations for electron and positron operations in the linac, PAR, and synchrotrons have been addressed else-where (MOE 93a, 93b, and 93c). Much of the methodology discussed in the previous writeups, as well as in MOE 94, has been used in the computations in this note. The radiological aspects that are addressed include the following: prompt secondary radiation (bremsstrahlung, giant resonance neutrons, medium- and high-energy neutrons) produced by electrons interacting in a beam stop or in component structures; skyshine radiation, which produces a radiation field in nearby areas and at the nearest off-site location; radioactive gases produced by neutron irradiation of air in the vicinity of a particle loss site; noxious gases (ozone and others) produced in air by the escaping bremsstrahlung radiation that results from absorbing particles in the components; activation of the LEUTL components that results in a residual radiation field in the vicinity of these materials following shutdown; potential activation of water used for cooling the magnets and other purposes in the tunnel; and evaluation of the radiation fields due to escaping gas bremsstrahlung. Estimated dose rates have been computed or scaled (in the case of 400 MeV electrons) outside of the bermed tunnel, in Building 412, and in the Klystron Gallery for several modes of operation, including potential safety envelope beam power, normal beam power and MCI (maximum credible incident) conditions. Radiological aspects of shielding changes to the synchrotrons and their effect upon operations are addressed in MOE 97. No change in the safety envelope for synchrotrons operation was warranted.« less

"Data like a movie instead of a photo” - continuous water sensor data collection, 2015 Lake MI CSMI

EPA Science Inventory

During the 2015 Lake Michigan CSMI effort we collected continuous undulating tow and autonomous glider data including conductivity, temperature, depth, fluorescence, and backscatter across the northern half of Lake Michigan. During the same period, we also collected discreet vert...

Study of Storage Ring Free-Electron Laser Using Experimental and Simulation Approaches

NASA Astrophysics Data System (ADS)

Jia, Botao

2011-12-01

The Duke electron storage ring, first commissioned in November of 1994, has been developed as a dedicated driver for storage ring free-electron lasers (SRFELs) operating in a wide wavelength range from infrared, to visible, to ultraviolet (UV) and vacuum ultraviolet (VUV). The storage ring has a long straight section for various insertion devices and can be operated in a wide energy range (0.25 GeV to 1.15 GeV). Commissioned in 1995, the first free-electron laser (FEL) on the Duke storage ring was the OK-4 FEL, an optical klystron with two planar undulators sandwiching a buncher magnet. In 2005, the OK-5 FEL with two helical undulators was commissioned. Operating four undulators---two OK-4 and two OK-5 undulators, the world's first distributed optical klystron FEL was brought to operation in 2005. Via Compton scattering of FEL photons and electrons in the storage ring, the Duke FEL drives the world's most powerful, nearly monochromatic, and polarized Compton gamma-ray source, the High Intensity Gamma-ray Source (HIgammaS). Today, a variety of configurations of the storage ring FELs at Duke have been used in a wide range of research areas from nuclear physics to biophysics, from chemical and medical research to industrial applications. The capability of accurately measuring the storage ring electron beam energy spread is crucial for understanding the longitudinal beam dynamics and the dynamics of the storage ring FEL. In this dissertation, we have successfully developed a noninvasive, versatile, and accurate method to measure the energy spread using optical klystron radiation. Novel numerical methods based upon the Gauss-Hermite expansion have been developed to treat both spectral broadening and modulation on an equal footing. Through properly configuring the optical klystron, this energy spread measurement method has a large dynamic range. In addition, a model-based scheme has been developed for correcting the electron beam emittance related inhomogeneous spectral broadening effect, to further enhance the accuracy of measuring the electron beam energy spread. Taking advantage of the direct measurement method of the electron beam energy spread, we have developed another novel technique to simultaneously measure the FEL power, electron beam energy spread, and other beam parameters. This allowed us to study the FEL power in a systematic manner for the first time. Based on the experimental findings and results of the theoretical predictions, we have proposed a compact formula to predict the FEL power using only the knowledge of electron beam current, beam energy, and bunch length. As part of the dissertation work, we have developed a self-consistent numerical model to study the storage ring FEL. The simulation program models the electron beam propagation along the storage ring, multi-turn FEL interaction in the undulators, gradual intra-cavity optical power buildup, etc. This simulation code captures the main features of a storage ring FEL at different time and space scales. The simulated FEL gain has been benchmarked against measured gain and calculated gain with good agreement. The simulation package can provide comprehensive information about the FEL gain, optical pulse growth, electron beam properties, etc. In the near future, we plan to further improve the simulation model, by including additional physics effects such as microwave instability, to make it a more useful tool for FEL research.

Ode to Moore

ERIC Educational Resources Information Center

Wilbert, Nancy Corrigan

2011-01-01

Best known for his monumental abstract sculptures of reclining figures, Henry Moore's forms are generally pierced or have a hollow space within them. Some say that these "organic undulating forms" are reminiscent of the landscape of his home in Yorkshire, England. Moore was a giant in the world of sculpture and his large cast bronzes and marble…

A COMPARISON OF ILLUMINATION GEOMETRY-BASED METHODS FOR TOPOGRAPHIC CORRECTION OF QUICKBIRD IMAGES OF AN UNDULANT AREA

USDA-ARS?s Scientific Manuscript database

The high spatial resolution of QuickBird satellite images makes it possible to show spatial variability at fine details. However, the effect of topography-induced illumination variations become more evident, even in moderately sloped areas. Based on a high resolution (1 m) digital elevation model ge...

Pathway to a compact SASE FEL device

NASA Astrophysics Data System (ADS)

Dattoli, G.; Di Palma, E.; Petrillo, V.; Rau, Julietta V.; Sabia, E.; Spassovsky, I.; Biedron, S. G.; Einstein, J.; Milton, S. V.

2015-10-01

Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cornacchia, Massimo

The VISA (Visible to Infrared SASE Amplifier) SASE free electron laser has been successfully operated at the Accelerator Test Facility (ATF) at BNL. High gain and saturation were observed at 840 nm. We describe here the diagnostic system, experimental procedures and data reduction algorithms, as the FEL performance was measured along the length of the undulator. We also discuss selected spectral radiation measurements.

Theoretical and simulation studies of seeding methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pellegrini, Claudio

We report the theoretical and experimental studies done with the support of DOE-Grant DE-SC0009983 to increase an X-ray FEL peak power from the present level of 20 to 40 GW to one or more TW by seeding, undulator tapering and using the new concept of the Double Bunch FEL.

Folds on Europa: implications for crustal cycling and accommodation of extension.

PubMed

Prockter, L M; Pappalardo, R T

2000-08-11

Regional-scale undulations with associated small-scale secondary structures are inferred to be folds on Jupiter's moon Europa. Formation is consistent with stresses from tidal deformation, potentially triggering compressional instability of a region of locally high thermal gradient. Folds may compensate for extension elsewhere on Europa and then relax away over time.

High brightness fully coherent x-ray amplifier seeded by a free-electron laser oscillator

NASA Astrophysics Data System (ADS)

Li, Kai; Yan, Jiawei; Feng, Chao; Zhang, Meng; Deng, Haixiao

2018-04-01

X-ray free-electron laser oscillator (XFELO) is expected to be a cutting-edge tool for fully coherent x-ray laser generation, and undulator taper technique is well-known for considerably increasing the efficiency of free-electron lasers (FELs). In order to combine the advantages of these two schemes, FEL amplifier seeded by XFELO is proposed by simply using a chirped electron beam. With the right choice of the beam parameters, the bunch tail is within the gain bandwidth of XFELO, and lase to saturation, which will be served as a seeding for further amplification. Meanwhile, the bunch head which is outside the gain bandwidth of XFELO, is preserved and used in the following FEL amplifier. It is found that the natural "double-horn" beam current, as well as residual energy chirp from chicane compressor, are quite suitable for the new scheme. Inheriting the advantages from XFELO seeding and undulator tapering, it is feasible to generate nearly terawatt level, fully coherent x-ray pulses with unprecedented shot-to-shot stability, which might open up new scientific opportunities in various research fields.

Polarization control in an X-ray free-electron laser

DOE PAGES

Lutman, Alberto A.; MacArthur, James P.; Ilchen, Markus; ...

2016-05-09

X-ray free-electron lasers are unique sources of high-brightness coherent radiation. However, existing devices supply only linearly polarized light, precluding studies of chiral dynamics. A device called the Delta undulator has been installed at the Linac Coherent Light Source (LCLS) to provide tunable polarization. With a reverse tapered planar undulator line to pre-microbunch the beam and the novel technique of beam diverting, hundreds of microjoules of circularly polarized X-ray pulses are produced at 500–1,200 eV. These X-ray pulses are tens of femtoseconds long, have a degree of circular polarization of 0.98 –0.04 +0.02 at 707 eV and may be scanned inmore » energy. We also present a new two-colour X-ray pump–X-ray probe operating mode for the LCLS. As a result, energy differences of ΔE/E = 2.4% are supported, and the second pulse can be adjusted to any elliptical polarization. In this mode, the pointing, timing, intensity and wavelength of the two pulses can be modified.« less

A method for ultra-short pulse-shape measurements using far infrared coherent radiation from an undulator

NASA Astrophysics Data System (ADS)

Geloni, G.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

2004-08-01

In this paper, we discuss a method for non-destructive measurements of the longitudinal profile of sub-picosecond electron bunches for X-ray free electron lasers. The method is based on the detection of the coherent synchrotron radiation (CSR) produced by a bunch passing through an undulator. Coherent radiation energy within a central cone turns out to be proportional, per pulse, to the square modulus of the bunch form-factor at the resonant frequency of the fundamental harmonic. An attractive feature of the proposed technique is the absence of any apparent limitation which would distort measurements. Indeed, the radiation process takes place in vacuum and is described by analytical formulae. CSR propagates to the detector placed in vacuum. Since CSR energy is in the range up to a fraction of mJ, a simple bolometer is used to measure the energy with a high accuracy. The proposed technique is very sensitive and it is capable of probing the electron bunches with a resolution down to a few microns.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kimura, Shin-Ichi; Ito, Takahiro; Hosaka, Masahito

A novel variably polarized angle-resolved photoemission spectroscopy beamline in the vacuum-ultraviolet (VUV) region has been installed at the UVSOR-II 750 MeV synchrotron light source. The beamline is equipped with a 3 m long APPLE-II type undulator with horizontally/vertically linear and right/left circular polarizations, a 10 m Wadsworth type monochromator covering a photon energy range of 6-43 eV, and a 200 mm radius hemispherical photoelectron analyzer with an electron lens of a {+-}18 deg. acceptance angle. Due to the low emittance of the UVSOR-II storage ring, the light source is regarded as an entrance slit, and the undulator light is directlymore » led to a grating by two plane mirrors in the monochromator while maintaining a balance between high-energy resolution and high photon flux. The energy resolving power (h{nu}/{Delta}h{nu}) and photon flux of the monochromator are typically 1x10{sup 4} and 10{sup 12} photons/s, respectively, with a 100 {mu}m exit slit. The beamline is used for angle-resolved photoemission spectroscopy with an energy resolution of a few meV covering the UV-to-VUV energy range.« less

Reversible beam heater for suppression of microbunching instability by transverse gradient undulators

NASA Astrophysics Data System (ADS)

Liu, Tao; Qin, Weilun; Wang, Dong; Huang, Zhirong

2017-08-01

The microbunching instability driven by beam collective effects in a linear accelerator of a free-electron laser (FEL) facility significantly degrades the electron beam quality and FEL performance. A conventional method to suppress this instability is to introduce an additional uncorrelated energy spread by laser-electron interaction, which has been successfully operated in the Linac Coherent Light Source and Fermi@Elettra, etc. Some other ideas are recently proposed to suppress the instability without increasing energy spread, which could benefit the seeded FEL schemes. In this paper, we propose a reversible electron beam heater using two transverse gradient undulators to suppress the microbunching instability. This scheme introduces both an energy spread increase and a transverse-to-longitudinal phase space coupling, which suppress the microbunching instabilities driven by both longitudinal space charge and coherent synchrotron radiation before and within the system. Finally the induced energy spread increase and emittance growth are reversed. Theoretical analysis and numerical simulations are presented to verify the feasibility of the scheme and indicate the capability to improve the seeded FEL radiation performance.

Isolated terawatt attosecond hard X-ray pulse generated from single current spike.

PubMed

Shim, Chi Hyun; Parc, Yong Woon; Kumar, Sandeep; Ko, In Soo; Kim, Dong Eon

2018-05-10

Isolated terawatt (TW) attosecond (as) hard X-ray pulse is greatly desired for four-dimensional investigations of natural phenomena with picometer spatial and attosecond temporal resolutions. Since the demand for such sources is continuously increasing, the possibility of generating such pulse by a single current spike without the use of optical or electron delay units in an undulator line is addressed. The conditions of a current spike (width and height) and a modulation laser pulse (wavelength and power) is also discussed. We demonstrate that an isolated TW-level as a hard X-ray can be produced by a properly chosen single current spike in an electron bunch with simulation results. By using realistic specifications of an electron bunch of the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), we show that an isolated, >1.0 TW and ~36 as X-ray pulse at 12.4 keV can be generated in an optimized-tapered undulator line. This result opens a new vista for current XFEL operation: the attosecond XFEL.

Convergent Evolution of Mechanically Optimal Locomotion in Aquatic Invertebrates and Vertebrates

PubMed Central

Bale, Rahul; Neveln, Izaak D.; Bhalla, Amneet Pal Singh

2015-01-01

Examples of animals evolving similar traits despite the absence of that trait in the last common ancestor, such as the wing and camera-type lens eye in vertebrates and invertebrates, are called cases of convergent evolution. Instances of convergent evolution of locomotory patterns that quantitatively agree with the mechanically optimal solution are very rare. Here, we show that, with respect to a very diverse group of aquatic animals, a mechanically optimal method of swimming with elongated fins has evolved independently at least eight times in both vertebrate and invertebrate swimmers across three different phyla. Specifically, if we take the length of an undulation along an animal’s fin during swimming and divide it by the mean amplitude of undulations along the fin length, the result is consistently around twenty. We call this value the optimal specific wavelength (OSW). We show that the OSW maximizes the force generated by the body, which also maximizes swimming speed. We hypothesize a mechanical basis for this optimality and suggest reasons for its repeated emergence through evolution. PMID:25919026

FEL Trajectory Analysis for the VISA Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nuhn, Heinz-Dieter

1998-10-06

The Visual to Infrared SASE Amplifier (VISA) [1] FEL is designed to achieve saturation at radiation wavelengths between 800 and 600 nm with a 4-m pure permanent magnet undulator. The undulator comprises four 99-cm segments each of which has four FODO focusing cells superposed on the beam by means of permanent magnets in the gap alongside the beam. Each segment will also have two beam position monitors and two sets of x-y dipole correctors. The trajectory walk-off in each segment will be reduced to a value smaller than the rms beam radius by means of magnet sorting, precise fabrication, andmore » post-fabrication shimming and trim magnets. However, this leaves possible inter-segment alignment errors. A trajectory analysis code has been used in combination with the FRED3D [2] FEL code to simulate the effect of the shimming procedure and segment alignment errors on the electron beam trajectory and to determine the sensitivity of the FEL gain process to trajectory errors. The paper describes the technique used to establish tolerances for the segment alignment.« less

Status of the development of Delhi Light Source (DLS) at IUAC

NASA Astrophysics Data System (ADS)

Ghosh, S.; Joshi, V.; Urakawa, J.; Terunuma, N.; Aryshev, A.; Fukuda, S.; Fukuda, M.; Sahu, B. K.; Patra, P.; Abhilash, S. R.; Karmakar, J.; Karmakar, B.; Kabiraj, D.; Kumar, N.; Sharma, A.; Chaudhari, G. K.; Pandey, A.; Tripathi, S.; Deshpande, A.; Naik, V.; Roy, A.; Rao, T.; Bhandari, R. K.; Kanjilal, D.

2017-07-01

A project to construct a compact pre-bunched Free Electron Laser by using a normal conducting photocathode electron gun has been undertaken at Inter University Accelerator Centre (IUAC), New Delhi, India. In this facility, the short laser pulses from a high power laser system will be split into many pulses (2-16) commonly known as 'Comb beam' and will strike the photocathode material (metal and semiconductor) to produce electron beam bunches. The electrons will be accelerated up to an energy of ∼8 MeV by a copper cavity operated at a frequency of 2860 MHz and the beam will be injected into a compact, planar permanent undulator magnet to produce THz radiation. The radiation frequency designed to be tuned in the range of 0.15-3 THz by varying the magnetic field of the undulator and/or changing the energy of the electron. The separation of the laser micro-pulses will be varied by adjusting the path length difference to alter the separation of the electron micro-bunches and to maximise the radiation intensity.

Reversible beam heater for suppression of microbunching instability by transverse gradient undulators

DOE PAGES

Liu, Tao; Qin, Weilun; Wang, Dong; ...

2017-08-02

The microbunching instability driven by beam collective effects in a linear accelerator of a free-electron laser (FEL) facility significantly degrades the electron beam quality and FEL performance. A conventional method to suppress this instability is to introduce an additional uncorrelated energy spread by laser-electron interaction, which has been successfully operated in the Linac Coherent Light Source and Fermi@Elettra, etc. Some other ideas are recently proposed to suppress the instability without increasing energy spread, which could benefit the seeded FEL schemes. In this paper, we propose a reversible electron beam heater using two transverse gradient undulators to suppress the microbunching instability.more » This scheme introduces both an energy spread increase and a transverse-to-longitudinal phase space coupling, which suppress the microbunching instabilities driven by both longitudinal space charge and coherent synchrotron radiation before and within the system. Finally the induced energy spread increase and emittance growth are reversed. In conclusion, theoretical analysis and numerical simulations are presented to verify the feasibility of the scheme and indicate the capability to improve the seeded FEL radiation performance.« less

OPERATIONAL EXPERIENCE WITH BEAM ABORT SYSTEM FOR SUPERCONDUCTING UNDULATOR QUENCH MITIGATION*

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harkay, Katherine C.; Dooling, Jeffrey C.; Sajaev, Vadim

A beam abort system has been implemented in the Advanced Photon Source storage ring. The abort system works in tandem with the existing machine protection system (MPS), and its purpose is to control the beam loss location and, thereby, minimize beam loss-induced quenches at the two superconducting undulators (SCUs). The abort system consists of a dedicated horizontal kicker designed to kick out all the bunches in a few turns after being triggered by MPS. The abort system concept was developed on the basis of single- and multi-particle tracking simulations using elegant and bench measurements of the kicker pulse. Performance ofmore » the abort system—kick amplitudes and loss distributions of all bunches—was analyzed using beam position monitor (BPM) turn histories, and agrees reasonably well with the model. Beam loss locations indicated by the BPMs are consistent with the fast fiber-optic beam loss monitor (BLM) diagnostics described elsewhere [1,2]. Operational experience with the abort system, various issues that were encountered, limitations of the system, and quench statistics are described.« less

Orbit Correction for the Newly Developed Polarization-Switching Undulator

NASA Astrophysics Data System (ADS)

Obina, Takashi; Honda, Tohru; Shioya, Tatsuro; Kobayashi, Yukinori; Tsuchiya, Kimichika; Yamamoto, Shigeru

2007-01-01

A new scheme of undulator magnet arrangements has been proposed and developed as a polarization-switching radiation source, and its test-stand was installed in the 2.5-GeV Photon Factory storage ring (PF ring) in order to investigate the effects on the beam orbit. The closed orbit distortion (COD) over 200 μm was produced in a vertical direction when we switched the polarization of the radiation from the test-stand. In a horizontal direction, the COD was less than 50μm. The results agreed well with the predictions from the magnetic-field measurement on the bench. In order to suppress the CODs and realize a stable operation of the ring with the polarization-switching, we developed an orbit correction system which consists of an encoder to detect motion of magnets, a pair of beam position monitors (BPMs), signal processing parts, and a pair of steering magnets. We succeeded in suppressing the CODs to the level below 3μm using the system even when we switch the polarization at a maximum frequency of 0.8 Hz.

On possible microscopic origins of the swelling of neutral lipid bilayers induced by simple salts.

PubMed

Manciu, Marian; Ruckenstein, Eli

2007-05-01

It was recently suggested that the swelling of neutral multilipid bilayers upon addition of a salt can be simply explained only by the electrolyte screening of the van der Waals attractions, while assuming that the hydration force and the repulsion due to thermal undulations of membranes are unaffected by the salt. While we agree that the screening of the van der Waals interactions plays a role, we suggest that the increase in the hydration force upon addition of a salt has also to be taken into account. In a statistical model, which accounts for the membrane undulations, parameters could be found to explain the multibilayer swelling even when the van der Waals attraction is considered unaffected by the electrolyte screening. These results point out that the decrease by a factor of three of the Hamaker constant upon addition of a salt, suggested recently to be responsible for the swelling of neutral multilipid bilayers, is perhaps too large, and a smaller decrease in Hamaker constant, coupled with the above mentioned effects might explain the swelling.

GINGER simulations of short-pulse effects in the LEUTL FEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Z.; Fawley, W.M.

While the long-pulse, coasting beam model is often used in analysis and simulation of self-amplified spontaneous emission (SASE) free-electron lasers (FELs), many current SASE demonstration experiments employ relatively short electron bunches whose pulse length is on the order of the radiation slippage length. In particular, the low-energy undulator test line (LEUTL) FEL at the Advanced Photon Source has recently lased and nominally saturated in both visible and near-ultraviolet wavelength regions with a sub-ps pulse length that is somewhat shorter than the total slippage length in the 22-m undulator system. In this paper we explore several characteristics of the short pulsemore » regime for SASE FELs with the multidimensional, time-dependent simulation code GINGER, concentrating on making a direct comparison with the experimental results from LEUTL. Items of interest include the radiation gain length, pulse energy, saturation position, and spectral bandwidth. We address the importance of short-pulse effects when scaling the LEUTL results to proposed x-ray FELs and also briefly discuss the possible importance of coherent spontaneous emission at startup.« less

Thermoforming of glass fibre reinforced polypropylene: A study on the influence of different process parameters

NASA Astrophysics Data System (ADS)

Schug, Alexander; Winkelbauer, Jonas; Hinterhölzl, Roland; Drechsler, Klaus

2017-10-01

The aim of this study was to analyse the forming behaviour of glass fibre reinforced polypropylene and to identify the influence of several process parameters on the resulting part quality. For this purpose, a complex forming tool was designed, consisting of several areas with single and double curvature. The specimens were produced from unidirectional (UD) tape using the Fiberforge RELAY2000® automated tape laying machine and a subsequent consolidation step. They were then fixed in a support frame, pre-heated in an infrared oven, and formed in the forming tool, which was mounted into a hydraulic heating press. The investigated process parameters were the number and force of the springs in the support frame, the tool temperature and the forming pressure and speed. The layups of the specimens were [0/90/0/90/0¯]s and [0/45/90/-45/0¯]s. After the forming process, the parts were analysed in terms of their quality, with a special focus on wrinkles, undulations, gaps and surface roughness. In addition to optical analysis with a statistical evaluation of the results, 3D scans of the specimens at different steps of the forming process were made to gain an impression of the forming mechanisms and the development of failures. The ATOS system of GOM was used for these 3D scans. The results show that the undulations were influenced by the tool temperature and the spring force. By contrast, the surface quality was most strongly dependent on the forming pressure, which also influenced the size and the number of gaps. The forming speed affected the gaps as well. The tool temperature had the largest influence on the development of wrinkles. As expected, the quasi-isotropic layup showed distinctly more wrinkles and undulations, but it also presented a better surface quality than the orthotropic layup.

a Matlab Geodetic Software for Processing Airborne LIDAR Bathymetry Data

NASA Astrophysics Data System (ADS)

Pepe, M.; Prezioso, G.

2015-04-01

The ability to build three-dimensional models through technologies based on satellite navigation systems GNSS and the continuous development of new sensors, as Airborne Laser Scanning Hydrography (ALH), data acquisition methods and 3D multi-resolution representations, have contributed significantly to the digital 3D documentation, mapping, preservation and representation of landscapes and heritage as well as to the growth of research in this fields. However, GNSS systems led to the use of the ellipsoidal height; to transform this height in orthometric is necessary to know a geoid undulation model. The latest and most accurate global geoid undulation model, available worldwide, is EGM2008 which has been publicly released by the U.S. National Geospatial-Intelligence Agency (NGA) EGM Development Team. Therefore, given the availability and accuracy of this geoid model, we can use it in geomatics applications that require the conversion of heights. Using this model, to correct the elevation of a point does not coincide with any node must interpolate elevation information of adjacent nodes. The purpose of this paper is produce a Matlab® geodetic software for processing airborne LIDAR bathymetry data. In particular we want to focus on the point clouds in ASPRS LAS format and convert the ellipsoidal height in orthometric. The algorithm, valid on the whole globe and operative for all UTM zones, allows the conversion of ellipsoidal heights using the EGM2008 model. Of this model we analyse the slopes which occur, in some critical areas, between the nodes of the undulations grid; we will focus our attention on the marine areas verifying the impact that the slopes have in the calculation of the orthometric height and, consequently, in the accuracy of the in the 3-D point clouds. This experiment will be carried out by analysing a LAS APRS file containing topographic and bathymetric data collected with LIDAR systems along the coasts of Oregon and Washington (USA).

New Strategic Plan Takes the ALS into the Future

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirz, J.; Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794; Chemla, D. S.

2007-01-19

A new strategic plan is in place to upgrade the ALS so it can continue to address fundamental questions, such as size-dependent and dimensional-confinement phenomena at the nanoscale; correlation and complexity in physical, biological, and environmental systems; and temporal evolution, assembly, dynamics and ultrafast phenomena. Moreover, the growing number of ALS users (now exceeding 2,000 per year) requires increased attention. Accordingly, our plan concentrates on projects that will continue to make it possible for ALS users to address grand scientific and technological challenges with incisive world-class tools and quality user support. Our highest priority is to begin top-off operation, inmore » which electrons are injected into the storage ring at intervals of approximately 1 minute. The combination of top-off and concurrent development of small-gap in-vacuum undulators and superconducting undulators will allow an increase in brightness from eight to more than 100 times, depending on the specific undulators and photon energy range. As part of our core mission in the VUV and soft x-ray regions, we plan to exploit these accelerator developments to extend our capabilities for high spatial and temporal resolution and utilize the remarkable coherence properties of the ALS in a new generation of beamlines. Ranked by priority, several proposed beamlines will follow completion of five new beamlines already under construction or funded. The intellectual excitement of the ALS has been a powerful tool in the recruitment and retention of outstanding staff, but additional sustained efforts are required to increase diversity both in gender and in underrepresented groups. To this end, we intend to expand the ALS Doctoral Fellowship Program by giving special emphasis to underrepresented groups. We also envision a distinguished postdoctoral fellowship program with the same emphasis, to increase and diversify our pool of candidates for beamline scientist positions.« less

Waves in the Turbulent Layer during the Morning Transition to the Convective Boundary Layer at Dome C, Antarctica

NASA Astrophysics Data System (ADS)

Petenko, Igor; Argentini, Stefania; Mastrantonio, Giangiuseppe; Kallistratova, Margarita; Viola, Angelo; Sozzi, Roberto; Casasanta, Giampietro; Conidi, Alessandro

2015-04-01

During January-February 2014, observations were carried out at the Concordia station, Dome C, Antarctica to study the behaviour of atmospheric turbulence in lower two hundred meters. The behaviour of thermal turbulence was observed remotely using a specially developed high-resolution sodar. In contrast to the all previous observations, in this experiment the turbulence pattern in the boundary layer was observed by sodar beginning from the lowest height of ≈2 m and with vertical resolution < 2 m. Sodar measurements were accompanied by in-situ measurements of the relevant meteorological variables as well as of some turbulent characteristics. Typical patterns of the diurnal evolution of the spatial and temporal distribution of turbulence detected by sodar were analysed. This study focuses on the transition period between stable stratification and the developed convective activity under the capping temperature inversion layer. Thank to the high resolution of sodar measurements, for the first time it was found that during developing the convection near the surface, above, in the elevated turbulent layer, a clear wave activity occurs. Undulation inside the elevating turbulent layer was observed during the significant part of the time. Mainly, the form of these waves can be classified as "cat eyes". Oscillations of wavy layers indicated with intense thermal turbulence inside them were characterized by the use of the methods of spectral and correlation analysis. The main characteristics (spatial and temporal scales, vertical extension) of the undulation structures were determined. The prevailing periodicity of the observed undulations is estimated to be 40-50 s. A descend rate of wavy fine turbulent layers was estimated by different ways and varies in the range 1-2 m s-1. The time behaviour of the top and the bottom of wavy layers were determined for the whole observational period.

Depth and Diameter of the Parent Roots of Aspen Root Suckers

Treesearch

Robert E. Farmer

1962-01-01

Studies of the Populus tremuloides root system by Day (1944), Sandberg (1951) and Barnes (1959) have all shown lateral roots extending as much as 30 feet from tree base. These roots may branch extensively and sometimes exhibit an "undulating" growth habit. According to the above authors, suckers occur on the segments of these lateral roots...

Disturbance regimes and the historical range of variation in terrestrial ecosystems [Chapter 389

Treesearch

Robert Keane

2013-01-01

Picture a tranquil landscape with undulating topography, idyllic streams, scenic glades, and verdant vegetation. Left to its own devices, this landscape would gradually become dominated by late successional communities that would slowly shift in response to climate changes over long time periods. This scene often forms the foundation and reference for most land...

Spatial patterns in carbon storage in a lake states' landscape

Treesearch

J. C. Bell; D. F. Grigal; P. C. Bates; C. A. Butler

1996-01-01

We estimated total organic carbon storage (C -- kg m-2) in biomass, forest floor, and soil for a gently undulating glacial outwash landscape in east-central Minnesota (45° 25'N, 93° 10'W). Abandoned agricultural tracts are common, and nearly 40 percent of the area is wet mineral or organic soil. Quantitative models...

Vertical-Control Subsystem for Automatic Coal Mining

NASA Technical Reports Server (NTRS)

Griffiths, W. R.; Smirlock, M.; Aplin, J.; Fish, R. B.; Fish, D.

1984-01-01

Guidance and control system automatically positions cutting drums of double-ended longwall shearer so they follow coal seam. System determines location of upper interface between coal and shale and continuously adjusts cutting-drum positions, upward or downward, to track undulating interface. Objective to keep cutting edges as close as practicable to interface and thus extract as much coal as possible from seam.

How Theories of Perception Deploy the Line: Reconfiguring Students' Bodies through Topo-Philosophy

ERIC Educational Resources Information Center

de Freitas, Elizabeth

2014-01-01

In this essay Elizabeth de Freitas follows Tim Ingold's groundbreaking anthropological work on lines and their cultural and material significance to argue that the line is the engine of theory, be it the drawn line of inscription or mathematical measure, the exclusionary line of delineation, or the undulating generative line of flight. De…

Navigating the Kokosing: A Comparison between Honors and Private Liberal Arts Colleges

ERIC Educational Resources Information Center

Carnicom, Scott

2014-01-01

The Kokosing is a small river, barely a stream after a storm, which meanders its way through the gently undulating hills and farmland of central Ohio. Kenyon College is nestled among the trees atop a hill near the Kokosing. Kenyon is a private, selective, liberal arts college of about 1600 undergraduate students founded by an Episcopal bishop…

EUV wavefront metrology system in EUVA

NASA Astrophysics Data System (ADS)

Hasegawa, Takayuki; Ouchi, Chidane; Hasegawa, Masanobu; Kato, Seima; Suzuki, Akiyoshi; Sugisaki, Katsumi; Murakami, Katsuhiko; Saito, Jun; Niibe, Masahito

2004-05-01

An Experimental extreme ultraviolet (EUV) interferometer (EEI) using an undulator as a light source was installed in New SUBARU synchrotron facility at Himeji Institute of Technology (HIT). The EEI can evaluate the five metrology methods reported before. (1) A purpose of the EEI is to determine the most suitable method for measuring the projection optics of EUV lithography systems for mass production tools.

Comparison of the sensitivity of landscape-fire-succession models to variation in terrain, fuel pattern, climate and weather.

Treesearch

Geoffrey J. Cary; Robert E. Keane; Robert H. Gardner; Sandra Lavorel; Mike D. Flannigan; Ian D. Davies; Chao Li; James M. Lenihan; T. Scott Rupp; Florent Mouillot

2006-01-01

The purpose of this study was to compare the sensitivity of nlodelled area burned to environmental factors across a range of independently-developed landscape-fire-succession models. The sensitivity of area burned to variation in four factors, namely terrain (flat, undulating and mountainous), fuel pattern (finely and coarsely clumped), climate (observed, warmer &...

Comparison of the sensitivity of landscape-fire-succession models to variation in terrain, fuel pattern, climate and weather

Treesearch

Geoffrey J. Cary; Robert E. Keane; Robert H. Gardner; Sandra Lavorel; Michael D. Flannigan; Ian D. Davies; Chao Li; James M. Lenihan; T. Scott Rupp; Florent Mouillot

2006-01-01

The purpose of this study was to compare the sensitivity of modelled area burned to environmental factors across a range of independently-developed landscape-fire-succession models. The sensitivity of area burned to variation in four factors, namely terrain (flat, undulating and mountainous), fuel pattern (finely and coarsely clumped), climate (observed, warmer &...

Afforestation, restoration and regeneration -- Not all trees are created equal

Treesearch

Shaneka Lawson; Charles H. Michler

2014-01-01

Undulations in weather patterns have caused climate shifts of increased frequency and duration around the world. The need for additional research and model data on this pressing problem has resulted in a plethora of research groups examining a particular tree species or biome for negative effects of climate change. This review aims to (1) collect and merge recent...

Soft x-ray spectromicroscopy using compact scanning transmission x-ray microscope at the photon factory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeichi, Yasuo, E-mail: yasuo.takeichi@kek.jp; Inami, Nobuhito; Ono, Kanta

We report the stability and recent performances of a new type of scanning transmission X-ray microscopy. The optics and compact design of the microscope realized mobility and robust performance. Detailed consideration to the vibration control will be described. The insertion device upgraded to elliptical polarization undulator enabled linear dichroism and circular dichroism experiments.

Free electron laser

DOEpatents

Villa, Francesco

1990-01-01

A high gain, single-pass free electron laser formed of a high brilliance electron injector source, a linear accelerator which imparts high energy to the electron beam, and an undulator capable of extremely high magnetic fields, yet with a very short period. The electron injector source is the first stage (gap) of the linear accelerator or a radial line transformer driven by fast circular switch. The linear accelerator is formed of a plurality of accelerating gaps arranged in series. These gaps are energized in sequence by releasing a single pulse of energy which propagates simultaneously along a plurality of transmission lines, each of which feeds the gaps. The transmission lines are graduated in length so that pulse power is present at each gap as the accelerated electrons pass therethrough. The transmission lines for each gap are open circuited at their ends. The undualtor has a structure similar to the accelerator, except that the transmission lines for each gap are substantially short circuited at their ends, thus converting the electric field into magnetic field. A small amount of resistance is retained in order to generate a small electric field for replenishing the electron bunch with the energy lost as it traverses through the undulator structure.

Time-dependent multi-dimensional simulation studies of the electron output scheme for high power FELs

NASA Astrophysics Data System (ADS)

Hahn, S. J.; Fawley, W. M.; Kim, K.-J.; Edighoffer, J. A.

1995-04-01

We examine the performance of the so-called electron output scheme recently proposed by the Novosibirsk group [G.I. Erg et al., 15th Int. Free Electron Laser Conf., The Hague, The Netherlands, 1993, Book of Abstracts p. 50; Preprint Budker INP 93-75]. In this scheme, the key role of the FEL oscillator is to induce bunching, while an external undulator, called the radiator, then outcouples the bunched electron beam to optical energy via coherent emission. The level of the intracavity power in the oscillator is kept low by employing a transverse optical klystron (TOK) configuration, thus avoiding excessive thermal loading on the cavity mirrors. Time-dependent effects are important in the operation of the electron output scheme because high gain in the TOK oscillator leads to sideband instabilities and chaotic behavior. We have carried out an extensive simulation study by using 1D and 2D time-dependent codes and find that proper control of the oscillator cavity detuning and cavity loss results in high output bunching with a narrow spectral bandwidth. Large cavity detuning in the oscillator and tapering of the radiator undulator is necessary for the optimum output power.

Long wavelength undulations dominate dynamics in large surfactant membrane patches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipfert, Frederik; Holderer, Olaf; Frielinghaus, Henrich

2014-12-03

In this study, by exposing microemulsions to small (80 nm diameter) and large (500 nm) disk shaped clay particles we were able to show the presence of long wavelength undulations that only occur for large membrane patches. A combination of small angle neutron scattering (SANS) and neutron spin echo (NSE) experiments have been applied to study microemulsions. These, consisting of D 2O, d-decane and the surfactant C 10E 4, were used in connection with Laponite (small) and Nanofil (large) clay. To our knowledge our experiments show for the first time that the clay platelets induce lamellar ordering adjacent to themore » clay discs in the otherwise bicontinuous microemulsion. This is due to the fact that in purely structural investigations, radial averaging smears out the signature of the lamellar phase. For thermodynamically fluctuating membranes near interfaces the theory of Seifert predicts a cross-over of the dispersion relationship from k 2 to a k 3-dependence. Lastly, with the correlation length of the membrane patches being confined by the dimension of the clay platelets we were able to show that this in fact takes place but is only present for the larger Nanofil particles.« less

On radiation emission from a microbunched beam with wavefront tilt and its experimental observation

NASA Astrophysics Data System (ADS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2018-03-01

In this paper we compare experimental observations and theory of radiation emission from a microbunched beam with microbunching wavefront tilt with respect to the direction of motion. The theory refers to the work Tanaka et al. (2004) , which predicts, in this case, exponential suppression of coherent radiation along the kicked direction. The observations refer to a recent experiment performed at the LCLS (Nuhn et al., 2015; Lutman etal., 2016), where a microbunched beam was kicked by a bend and sent to a radiator undulator. The experiment resulted in the emission of strong coherent radiation that had its maximum along the kicked direction of motion, when the undulator parameter was detuned to a value larger than the nominal one. We first analyze the theory in detail, and we confirm the correctness of its derivation according to the conventional theory of radiation emission from charged particles. Subsequently, we look for possible peculiarities in the experiment, which may not be modeled by the theory. We show that only spurious effects are not accounted for. We conclude that the experiment defies explanation in terms of the conventional theory of radiation emission.

Terawatt x-ray free-electron-laser optimization by transverse electron distribution shaping

DOE PAGES

Emma, C.; Wu, J.; Fang, K.; ...

2014-11-03

We study the dependence of the peak power of a 1.5 Å Terawatt (TW), tapered x-ray free-electron laser (FEL) on the transverse electron density distribution. Multidimensional optimization schemes for TW hard x-ray free-electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to a Gaussian distribution. The optimizations are performed for a 200 m undulator and a resonant wavelength of λ r = 1.5 Å using the fully three-dimensional FEL particle code GENESIS. The study shows that the flatter transverse electron distributions enhance optical guiding in the tapered section of the undulator andmore » increase the maximum radiation power from a maximum of 1.56 TW for a transversely Gaussian beam to 2.26 TW for the parabolic case and 2.63 TW for the uniform case. Spectral data also shows a 30%–70% reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the transverse coherence of the radiation shows the coherence area to be much larger than the beam spotsize for all three distributions, making coherent diffraction imaging experiments possible.« less

Sinuous flow in metals

PubMed Central

Yeung, Ho; Viswanathan, Koushik; Compton, Walter Dale; Chandrasekar, Srinivasan

2015-01-01

Annealed metals are surprisingly difficult to cut, involving high forces and an unusually thick “chip.” This anomaly has long been explained, based on ex situ observations, using a model of smooth plastic flow with uniform shear to describe material removal by chip formation. Here we show that this phenomenon is actually the result of a fundamentally different collective deformation mode—sinuous flow. Using in situ imaging, we find that chip formation occurs via large-amplitude folding, triggered by surface undulations of a characteristic size. The resulting fold patterns resemble those observed in geophysics and complex fluids. Our observations establish sinuous flow as another mesoscopic deformation mode, alongside mechanisms such as kinking and shear banding. Additionally, by suppressing the triggering surface undulations, sinuous flow can be eliminated, resulting in a drastic reduction of cutting forces. We demonstrate this suppression quite simply by the application of common marking ink on the free surface of the workpiece material before the cutting. Alternatively, prehardening a thin surface layer of the workpiece material shows similar results. Besides obvious implications to industrial machining and surface generation processes, our results also help unify a number of disparate observations in the cutting of metals, including the so-called Rehbinder effect. PMID:26216980

Sinuous flow in metals.

PubMed

Yeung, Ho; Viswanathan, Koushik; Compton, Walter Dale; Chandrasekar, Srinivasan

2015-08-11

Annealed metals are surprisingly difficult to cut, involving high forces and an unusually thick "chip." This anomaly has long been explained, based on ex situ observations, using a model of smooth plastic flow with uniform shear to describe material removal by chip formation. Here we show that this phenomenon is actually the result of a fundamentally different collective deformation mode--sinuous flow. Using in situ imaging, we find that chip formation occurs via large-amplitude folding, triggered by surface undulations of a characteristic size. The resulting fold patterns resemble those observed in geophysics and complex fluids. Our observations establish sinuous flow as another mesoscopic deformation mode, alongside mechanisms such as kinking and shear banding. Additionally, by suppressing the triggering surface undulations, sinuous flow can be eliminated, resulting in a drastic reduction of cutting forces. We demonstrate this suppression quite simply by the application of common marking ink on the free surface of the workpiece material before the cutting. Alternatively, prehardening a thin surface layer of the workpiece material shows similar results. Besides obvious implications to industrial machining and surface generation processes, our results also help unify a number of disparate observations in the cutting of metals, including the so-called Rehbinder effect.

Surface self-organization in multilayer film coatings

NASA Astrophysics Data System (ADS)

Shuvalov, Gleb M.; Kostyrko, Sergey A.

2017-12-01

It is a recognized fact that during film deposition and subsequent thermal processing the film surface evolves into an undulating profile. Surface roughness affects many important aspects in the engineering application of thin film materials such as wetting, heat transfer, mechanical, electromagnetic and optical properties. To accurately control the morphological surface modifications at the micro- and nanoscale and improve manufacturing techniques, we design a mathematical model of the surface self-organization process in multilayer film materials. In this paper, we consider a solid film coating with an arbitrary number of layers under plane strain conditions. The film surface has a small initial perturbation described by a periodic function. It is assumed that the evolution of the surface relief is governed by surface and volume diffusion. Based on Gibbs thermodynamics and linear theory of elasticity, we present a procedure for constructing a governing equation that gives the amplitude change of the surface perturbation with time. A parametric study of the evolution equation leads to the definition of a critical undulation wavelength that stabilizes the surface. As a numerical result, the influence of geometrical and physical parameters on the morphological stability of an isotropic two-layered film coating is analyzed.

Applications of laser wakefield accelerator-based light sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albert, Felicie; Thomas, Alec G. R.

Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons inmore » the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.« less

Numerical Study of Winter Diurnal Convection Over the City of Krasnoyarsk: Effects of Non-freezing River, Undulating Fog and Steam Devils

NASA Astrophysics Data System (ADS)

Hrebtov, M.; Hanjalić, K.

2017-06-01

We performed a numerical simulation of penetrative convection of an inversion-topped weakly stratified atmospheric boundary layer over urban terrain with a strong localized source of heat and moisture. With some simplifications, the case mimics the real environment of the Krasnoyarsk region in Russia where the non-freezing river Yenisei acts as a thermal and humidity source during winter, generating an undulating fog pattern along the river accompanied with scattered `steam devils'. An idealized full diurnal cycle was simulated using an unsteady Reynolds-averaged Navier-Stokes (RANS) three-equation algebraic flux model and the novel buoyancy-accounting functions for treating the ground boundary conditions. The results show a significant effect of the river on the net temperature and moisture distribution. The localized heat and moisture source leads to strong horizontal convection and marked non-uniformity of humidity concentration in the air. An interplay of several distinct large-scale vortex systems leads to a wavy pattern of moisture plumes over the river. The simulations deal with rare natural phenomena and show the capability of the RANS turbulence closure to capture the main features of flow and scalar fields on an affordable, relatively coarse, computational grid.

An analytical study on groundwater flow in drainage basins with horizontal wells

NASA Astrophysics Data System (ADS)

Wang, Jun-Zhi; Jiang, Xiao-Wei; Wan, Li; Wang, Xu-Sheng; Li, Hailong

2014-06-01

Analytical studies on release/capture zones are often limited to a uniform background groundwater flow. In fact, for basin-scale problems, the undulating water table would lead to the development of hierarchically nested flow systems, which are more complex than a uniform flow. Under the premise that the water table is a replica of undulating topography and hardly influenced by wells, an analytical solution of hydraulic head is derived for a two-dimensional cross section of a drainage basin with horizontal injection/pumping wells. Based on the analytical solution, distributions of hydraulic head, stagnation points and flow systems (including release/capture zones) are explored. The superposition of injection/pumping wells onto the background flow field leads to the development of new internal stagnation points and new flow systems (including release/capture zones). Generally speaking, the existence of n injection/pumping wells would result in up to n new internal stagnation points and up to 2n new flow systems (including release/capture zones). The analytical study presented, which integrates traditional well hydraulics with the theory of regional groundwater flow, is useful in understanding basin-scale groundwater flow influenced by human activities.

Legless locomotion in lattices

NASA Astrophysics Data System (ADS)

Schiebel, Perrin; Dai, Jin; Gong, Chaohui; Serrano, Miguel M.; Mendelson, Joseph R., III; Choset, Howie; Goldman, Daniel I.

2015-03-01

By propagating waves from head to tail, limbless organisms like snakes can traverse terrain composed of rocks, foliage, soil and sand. Previous research elucidated how rigid obstacles influence snake locomotion by studying a model terrain-symmetric lattices of pegs placed in hard ground. We want to understand how different substrate-body interaction modes affect performance in desert-adapted snakes during transit of substrates composed of both rigid obstacles and granular media (GM). We tested Chionactis occipitalis, the Mojave shovel-nosed snake, in two laboratory treatments: lattices of 0 . 64 cm diameter obstacles arrayed on both a hard, slick substrate and in a GM of ~ 0 . 3 mm diameter glass particles. For all lattice spacings, d, speed through the hard ground lattices was less than that in GM lattices. However, maximal undulation efficiencies ηu (number of body lengths advanced per undulation cycle) in both treatments were comparable when d was intermediate. For other d, ηu was lower than this maximum in hard ground lattices, while on GM, ηu was insensitive to d. To systematically explore such locomotion, we tested a physical robot model of the snake; performance depended sensitively on base substrate, d and body wave parameters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartmann, G.; Shevchuk, I.; Walter, P.

A non-destructive diagnostic method for the characterization of circularly polarized, ultraintense, short wavelength free-electron laser (FEL) light is presented. The recently installed Delta undulator at the LCLS (Linac Coherent Light Source) at SLAC National Accelerator Laboratory (USA) was used as showcase for this diagnostic scheme. By applying a combined two-color, multi-photon experiment with polarization control, the degree of circular polarization of the Delta undulator has been determined. Towards this goal, an oriented electronic state in the continuum was created by non-resonant ionization of the O{sub 2} 1s core shell with circularly polarized FEL pulses at hν ≃ 700 eV. Anmore » also circularly polarized, highly intense UV laser pulse with hν ≃ 3.1 eV was temporally and spatially overlapped, causing the photoelectrons to redistribute into so-called sidebands that are energetically separated by the photon energy of the UV laser. By determining the circular dichroism of these redistributed electrons using angle resolving electron spectroscopy and modeling the results with the strong-field approximation, this scheme allows to unambiguously determine the absolute degree of circular polarization of any pulsed, ultraintense XUV or X-ray laser source.« less

Circular dichroism measurements at an x-ray free-electron laser with polarization control

NASA Astrophysics Data System (ADS)

Hartmann, G.; Lindahl, A. O.; Knie, A.; Hartmann, N.; Lutman, A. A.; MacArthur, J. P.; Shevchuk, I.; Buck, J.; Galler, A.; Glownia, J. M.; Helml, W.; Huang, Z.; Kabachnik, N. M.; Kazansky, A. K.; Liu, J.; Marinelli, A.; Mazza, T.; Nuhn, H.-D.; Walter, P.; Viefhaus, J.; Meyer, M.; Moeller, S.; Coffee, R. N.; Ilchen, M.

2016-08-01

A non-destructive diagnostic method for the characterization of circularly polarized, ultraintense, short wavelength free-electron laser (FEL) light is presented. The recently installed Delta undulator at the LCLS (Linac Coherent Light Source) at SLAC National Accelerator Laboratory (USA) was used as showcase for this diagnostic scheme. By applying a combined two-color, multi-photon experiment with polarization control, the degree of circular polarization of the Delta undulator has been determined. Towards this goal, an oriented electronic state in the continuum was created by non-resonant ionization of the O2 1s core shell with circularly polarized FEL pulses at hν ≃ 700 eV. An also circularly polarized, highly intense UV laser pulse with hν ≃ 3.1 eV was temporally and spatially overlapped, causing the photoelectrons to redistribute into so-called sidebands that are energetically separated by the photon energy of the UV laser. By determining the circular dichroism of these redistributed electrons using angle resolving electron spectroscopy and modeling the results with the strong-field approximation, this scheme allows to unambiguously determine the absolute degree of circular polarization of any pulsed, ultraintense XUV or X-ray laser source.

Optimizing an undulating magnetic microswimmer for cargo towing

NASA Astrophysics Data System (ADS)

Or, Yizhar; Gutman, Emiliya

2015-11-01

One of the promising applications of robotic microswimmers is towing a cargo for controlled drug delivery, micro-surgery or tumor detection. This capability has been demonstrated by the magnetically-actuated microswimmer of Dreyfus et al. [Nature 2005] in which a red blood cell was attached to a chain of magnetic beads connected by flexible DNA links. A key question is what should be the optimal size of the magnetic tail for towing a given cargo. This question is addressed here for the simplest theoretical model of a magnetic microswimmer under planar undulations - a spherical load connected by a torsion spring to a magnetized rigid slender link. The swimmer's dynamics is formulated assuming negligible hydrodynamic interaction and leading-order expressions for the resulting motion are obtained explicitly under small amplitude approximation. Optimal combinations of magnetic actuation frequency, torsion stiffness, and tail length for maximizing displacement or average speed are obtained. The theoretical results are compared with several reported magnetic microswimmers, and also agree qualitatively with recent results on cargo towing by screw rotation of magnetic helical tails [Walker et al., ACS Nano Letters 2015]. This work is supported by the Israeli Science Foundation (ISF) under Grant No. 567/14.

Self-consistent analysis of radiation and relativistic electron beam dynamics in a helical wiggler using Lienard-Wiechert fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tecimer, M.; Elias, L.R.

1995-12-31

Lienard-Wiechert (LW) fields, which are exact solutions of the Wave Equation for a point charge in free space, are employed to formulate a self-consistent treatment of the electron beam dynamics and the evolution of the generated radiation in long undulators. In a relativistic electron beam the internal forces leading to the interaction of the electrons with each other can be computed by means of retarded LW fields. The resulting electron beam dynamics enables us to obtain three dimensional radiation fields starting from an initial incoherent spontaneous emission, without introducing a seed wave at start-up. Based on the formalism employed here,more » both the evolution of the multi-bucket electron phase space dynamics in the beam body as well as edges and the relative slippage of the radiation with respect to the electrons in the considered short bunch are naturally embedded into the simulation model. In this paper, we present electromagnetic radiation studies, including multi-bucket electron phase dynamics and angular distribution of radiation in the time and frequency domain produced by a relativistic short electron beam bunch interacting with a circularly polarized magnetic undulator.« less

Applications of laser wakefield accelerator-based light sources

DOE PAGES

Albert, Felicie; Thomas, Alec G. R.

2016-10-01

Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons inmore » the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.« less

Testing Momentum Enhancement of Ribbon Fin Based Propulsion Using a Robotic Model With an Adjustable Body

NASA Astrophysics Data System (ADS)

English, Ian; Curet, Oscar

2016-11-01

Lighthill and Blake's 1990 momentum enhancement theory suggests there is a multiplicative propulsive effect linked to the ratio of body and fin heights in Gymnotiform and Balistiform swimmers, which propel themselves using multi-rayed undulating fins while keeping their bodies mostly rigid. Proof of such a momentum enhancement could have a profound effect on unmanned underwater vehicle design and shed light on the evolutionary advantage to body-fin ratios found in nature, shown as optimal for momentum enhancement in Lighthill and Blake's theory. A robotic ribbon fin with twelve independent fin rays, elastic fin membrane, and a body of adjustable height was developed specifically to experimentally test momentum enhancement. Thrust tests for various body heights were conducted in a recirculating flow tank at different flow speeds and fin flapping frequencies. When comparing thrust at different body heights, flow speeds, and frequencies to a 'no-body' thrust test case at each frequency and flow speed, data indicate there is no momentum enhancement factor due to the presence of a body on top of an undulating fin. This suggests that if there is a benefit to a specific ratio between body and fin height, it is not due to momentum enhancement.

Flow over a traveling wavy foil with a passively flapping flat plate

NASA Astrophysics Data System (ADS)

Liu, Nansheng; Peng, Yan; Liang, Youwen; Lu, Xiyun

2012-05-01

Flow over a traveling wavy foil with a passively flapping flat plate has been investigated using a multiblock lattice Boltzmann equation and the immersed boundary method. The foil undergoes prescribed undulations in the lateral direction and the rigid flat plate has passive motion determined by the fluid structure interaction. This simplified model is used to study the effect of the fish caudal fin and its flexibility on the locomotion of swimming animals. The flexibility of the caudal fin is modeled by a torsion spring acting about the pivot at the conjuncture of the wavy foil and the flat plate. The study reveals that the passively oscillating flat plate contributes half of the propulsive force. The flexibility, represented by the nondimensional natural frequency F, plays a very important role in the movement and propulsive force generation of the whole body. When the plate is too flexible, the drag force is observed. As the flat plate becomes more rigid, the propulsive force that is generated when the undulation is confined to last part of the wavy foil becomes larger. The steady movement occurs at F=5. These results are consistent with the observations of some swimming animals in nature.

Use of geoprocessing to define malaria risk areas and evaluation of the vectorial importance of anopheline mosquitoes (Diptera: Culicidae) in Espírito Santo, Brazil.

PubMed

Meneguzzi, Viviane Coutinho; Santos, Claudiney Biral dos; Pinto, Israel de Souza; Feitoza, Leandro Roberto; Feitoza, Hideko Nagatani; Falqueto, Aloísio

2009-07-01

In Brazil, introduced malaria occurs from the flat to the sloping hot areas, predominantly outside the Amazon Region, where endemic malaria has occurred in the past. This is a consequence of human migrations to other Brazilian states, including the state of Espírito Santo (ES). The objective of this study was to use geoprocessing to define the areas at risk of introduced malaria transmission and evaluate the vectorial importance of species of anophelines in ES. Anophelines were sampled from 1997-2005 in 297 rural localities identified or not identified as foci of malaria during the last 20 years. The geoclimatic variables temperature, relief and marine influence were obtained from a database of the ES Natural Units. The 14,663 anophelines captured belonged to 22 species. A significant association was found between the occurrence of malaria foci and the presence of hot, low-lying areas or gently undulating to undulating relief. The occurrence of the disease was associated with the presence of Anopheles darlingi and Anopheles aquasalis. Geoprocessing was determined to be a useful tool for defining areas at risk for malaria and vectors in ES.

Quick-scanning x-ray absorption spectroscopy system with a servo-motor-driven channel-cut monochromator with a temporal resolution of 10 ms.

PubMed

Nonaka, T; Dohmae, K; Araki, T; Hayashi, Y; Hirose, Y; Uruga, T; Yamazaki, H; Mochizuki, T; Tanida, H; Goto, S

2012-08-01

We have developed a quick-scanning x-ray absorption fine structure (QXAFS) system and installed it at the recently constructed synchrotron radiation beamline BL33XU at the SPring-8. Rapid acquisition of high-quality QXAFS data was realized by combining a servo-motor-driven Si channel-cut monochromator with a tapered undulator. Two tandemly aligned monochromators with channel-cut Si(111) and Si(220) crystals covered energy ranges of 4.0-28.2 keV and 6.6-46.0 keV, respectively. The system allows the users to adjust instantly the energy ranges of scans, the starting angles of oscillations, and the frequencies. The channel-cut crystals are cooled with liquid nitrogen to enable them to withstand the high heat load from the undulator radiation. Deformation of the reflecting planes is reduced by clamping each crystal with two cooling blocks. Performance tests at the Cu K-edge demonstrated sufficiently high data quality for x-ray absorption near-edge structure and extended x-ray absorption fine-structure analyses with temporal resolutions of up to 10 and 25 ms, respectively.

The EMIL project at BESSY II: Beamline design and performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendel, Stefan, E-mail: stefan.hendel@helmholtz-berlin.de; Schäfers, Franz; Reichardt, Gerd

2016-07-27

The Energy Materials In-Situ Laboratory Berlin (EMIL) at BESSY-II is currently under construction. Two canted undulators for soft- and hard X-rays will be installed into the BESSY II storage ring in one straight section, complex beamlines with more than twenty optical elements will be set up and a new laboratory building attached to BESSY II will host three endstations and a large UHV-transfer system connecting various HV- and UHV-deposition systems. The undulators, UE48 and U17, provide a broad energy spectrum of 80 - 10000 eV, of which the harder radiation (>700 eV) is provided by a cryogenic in-vacuum device. Threemore » monochromators (two plane grating monochromators (PGM) and one LN{sub 2}-cooled double crystal monochromator (DCM)) disperse the radiation into separate pathways of 65 m length, while downstream of the monochromators split-mirror chambers distribute the photon beam to one (or simultaneously to two) of five upcoming endstations. Three of these endstations are designed for the full energy range with spatial overlap of the soft and hard foci, whereas one endstation (PEEM) uses only the soft and another one (PINK) only the hard branch, respectively.« less

Numerical study of the 3-D effect on FEL performance and its application to the APS LEUTL FEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chae, Y.C.

A Low-Energy Undulator Test Line (LEUTL) is under construction at the Advanced Photon Source (APS). In LEUTL periodic focusing is provided by external quadrupoles. This results in an elliptical beam with its betatron oscillation envelope varying along the undulators. The free-electron laser (FEL) interaction with such a beam will exhibit truly 3-D effects. Thus the investigation of 3-D effects is important in optimizing the FEL performance. The programs GINGER and TDA3D, coupled with theoretically known facts, have been used for this purpose. Both programs are fully 3-D in moving the particle, but model the interaction between particles and axially symmetricmore » electromagnetic waves. Even though TDA3D can include a few azimuthal modes in the interaction, it is still not a fully 3-D FEL code. However, they show that these 2-D programs can still be used for an elliptical beam whose aspect ratio is within certain limits. The author presents numerical results of FEL performance for the circular beam, the elliptical beam, and finally for the beam in the realistic LEUTL lattice.« less

Mechanics of the Cell

NASA Astrophysics Data System (ADS)

Boal, David

2012-01-01

Preface; List of symbols; 1. Introduction to the cell; 2. Soft materials and fluids; Part I. Rods and Ropes: 3. Polymers; 4. Complex filaments; 5. Two-dimensional networks; 6. Three-dimensional networks; Part II. Membranes: 7. Biomembranes; 8. Membrane undulations; 9. Intermembrane and electrostatic forces; Part III. The Whole Cell: 10. Structure of the simplest cells; 11. Dynamic filaments; 12. Growth and division; 13. Signals and switches; Appendixes; Glossary; References; Index.

Microwave Emission From Relativistic Electron Beams

DTIC Science & Technology

1993-04-12

the Army position, policyX, or decision, unless so designated by other documentation. 124. DISTRIBUTION i AVAILAOILITY STATEMENT I 12b. DISTRIBUTION...klystron (inodel 343). An assembly of six focusing coils is de - signed so that their magnetic field lines lie along the zero-magnetic field electron...less than 1% is achieved. Preliminary field measurements of a 30 period prototype undulator and the design parameters of a submillimeter experiment

Applications of Geodesy to Geodynamics, an International Symposium

NASA Technical Reports Server (NTRS)

Mueller, I. I. (Editor)

1978-01-01

Geodetic techniques in detecting and monitoring geodynamic phenomena are reviewed. Specific areas covered include: rotation of the earth and polar motion; tectonic plate movements and crustal deformations (space techniques); horizontal crustal movements (terrestrial techniques); vertical crustal movements (terrestrial techniques); gravity field, geoid, and ocean surface by space techniques; surface gravity and new techniques for the geophysical interpretation of gravity and geoid undulation; and earth tides and geodesy.

Compact single-pass X-ray FEL with harmonic multiplication cascades

NASA Astrophysics Data System (ADS)

Zhukovsky, K.

2018-07-01

The generation of X-ray radiation in cascaded single-pass free electron laser (FEL), which amplifies high harmonics of a two-frequency undulator, is studied. Power dynamics of FEL harmonics is explored with the help of the phenomenological model of a single pass FEL. The model describes both linear and non-linear harmonic generation, starting from a coherent seed laser and initial shot noise with account for main loss factors for each harmonic in each cascade individually: the energy spread and beam divergence, the coupling losses between FEL cascades, the diffraction etc. The model was validated with the experiment and with relevant 3-D simulations. It is employed for modeling the cascaded FELs with harmonic multiplication and analyzing the evolution of FEL harmonic power with the aim to obtain the maximum high harmonic power in the X-ray band at the shortest possible FEL length with the lowest possible seed frequency. The advantages of two-frequency undulators in HGHG FELs are elucidated. The requirements for the electron beam are studied; the need for low energy spread is evidenced: our evaluations yield σe < 2 × 10-4. Several cascaded HGHG FELs with two-frequency undulators are modeled. Generation of soft X-ray radiation at λ = 2 . 71 nm, reaching ∼50 MW power with I0 ∼ 100 A in a cascaded FEL at just 40 m with 13.51 nm seed, matching peak reflectivity of Mo/Si, is demonstrated. The generation of 40 MW radiation power at λ = 2 . 27 nm with the beam current I0 ∼ 100 A, energy E = 950 MeV and the energy spread σe = 2 × 10-4 is studied, using second and third harmonics in three-stage 45 m long FEL. The multistage FEL is modeled for generating radiation in nanometer band: ∼40 MW power at λ ∼ 2 . 6 nm with I0 ∼ 175 A current in just ∼40 m long FEL with commercially available F2 excimer UV laser seed at 157 nm. The peak radiation power rises to ∼0.5 GW for ∼1 kA beam current.

Patterned basal seismicity shows sub-ice stream bedforms

NASA Astrophysics Data System (ADS)

Barcheck, C. G.; Tulaczyk, S. M.; Schwartz, S. Y.

2017-12-01

Patterns in seismicity emanating from the bottom of fast-moving ice streams and glaciers may indicate localized patches of higher basal resistance— sometimes called 'sticky spots', or otherwise varying basal properties. These seismogenic basal areas resist an unknown portion of the total driving stress of the Whillans Ice Plain (WIP), in West Antarctica, but may play an important role in the WIP stick-slip cycle and ice stream slowdown. To better understand the mechanism and importance of basal seismicity beneath the WIP, we analyze seismic data collected by a small aperture (< 3km) network of 8 surface and 5 borehole seismometers installed in the main central sticky spot of the WIP. We use a network beamforming technique to detect and roughly locate thousands of small (magnitude < 0), local basal micro-earthquakes in Dec 2014, and we compare the resulting map of seismicity to ice bottom depth measured by airborne radar. The number of basal earthquakes per area within the network is spatially heterogeneous, but a pattern of two 400m wide streaks of high seismicity rates is evident, with >50-500 earthquakes detected per 50x50m grid cell in 2 weeks. These seismically active streaks are elongated approximately in the ice flow direction with a spacing of 750m. Independent airborne radar measurements of ice bottom depth from Jan 2013 show a low-amplitude ( 5m) undulation in the basal topography superposed on a regional gradient in ice bottom depth. The flow-perpendicular wavelength of these low-amplitude undulations is comparable to the spacing of the high seismicity bands, and the streaks of high seismicity intersect local lows in the undulating basal topography. We interpret these seismic and radar observations as showing seismically active sub-ice stream bedforms that are low amplitude and elongated in the direction of ice flow, comparable to the morphology of mega scale glacial lineations (MSGLs), with high basal seismicity rates observed in the MSGL troughs. These results have implications for understanding the formation mechanism of MSGLS and well as understanding the interplay between basal topographic roughness, spatially varying basal till and hydrologic properties, basal resistance to fast ice flow, and ice stream stick-slip.

A novel trypanoplasm-like flagellate Jarrellia atramenti n. g., n. sp. (Kinetoplastida: Bodonidae) and ciliates from the blowhole of a stranded pygmy sperm whale Kogia breviceps (Physeteridae): morphology, life cycle and potential pathogenicity.

PubMed

Poynton, S L; Whitaker, B R; Heinrich, A B

2001-04-10

The successful 6 mo rehabilitation of a stranded juvenile pygmy sperm whale Kogia breviceps afforded the opportunity to study the poorly known protozoan fauna of the upper respiratory tract of cetaceans. Mucus samples were collected by holding either a petri dish or glass slides over the blowhole for 3 to 5 exhalations; preparations were examined as wet mounts, and then stained with Wrights-Giemsa or Gram stain. Blood smears were stained with Wrights-Giemsa. Unidentified spindle-shaped and unidentified broad ciliates, reported from the blowhole of the pygmy sperm whale for the first time, were seen only initially, while yeast-like organisms and bacteria were seen intermittently. Epithelial cells and white blood cells were often present in the blowhole mucus, but red blood cells were never seen. A novel trypanoplasm-like bodonid kinetoplastid biflagellate (Order Kinetoplastida) was commonly encountered in the blowhole mucus, but never in the blood. Both mature flagellates and those undergoing longitudinal binary fission were present. The elongate flagellate had a long whiplash anterior flagellum; the recurrent flagellum was attached along at least two-thirds of the body length, forming a prominent undulating membrane, and the trailing portion was short. The kinetoplast was irregularly fragmented. The flagellates were either free-swimming, or attached to host material via the free portion of the posterior flagellum. The prominent undulating membrane was characteristic of Trypanoplasma, while the fragmented kinetoplast was characteristic of some species of Cryptobia. For the novel bodonid kinetoplastid, with its unique combination of morphological features (prominent undulating membrane and fragmented kinetoplast), we propose the creation of a new genus Jarrellia. We believe this to be the first published description of a flagellate from a marine mammal, and among the first reports of a trypanoplasm-like flagellate from a warm-blooded host. We expect that a diversity of flagellates and ciliates are commonly present in the blowhole of cetaceans. Future studies on the identity of the protozoans and the health of their cetacean hosts, which are readily studied in captivity, are necessary to establish their status as commensals or parasites.

Quantitative expression patterns of GDF9 and BMP15 genes in sheep ovarian follicles grown in vivo or cultured in vitro.

PubMed

Kona, S S R; Praveen Chakravarthi, V; Siva Kumar, A V N; Srividya, D; Padmaja, K; Rao, V H

2016-01-15

Quantitative patterns of expression of the growth differentiation factor 9 (GDF9) and bone morphogenic protein 15 (BMP15) genes in different development stages of in vivo and in vitro grown ovarian follicles in sheep were studied for the first time. Both GDF9 and BMP15 were expressed in the cumulus cells and oocytes at all the development stages of in vivo and in vitro grown ovarian follicles. Growth differentiation factor 9 and bone morphogenic protein 15 exhibited stage-specific undulations in the expression in the cumulus cells and oocytes isolated from in vivo grown ovarian follicles. These undulations could be related to discrete development events during the ovarian follicle development. The expression of GDF9 and BMP15 was highest (3.38 ± 0.02 and 2.69 ± 0.06, respectively; P ≤ 0.05) in the primordial follicles compared with preantral, early antral, antral, and large antral stages. Similarly, GDF9 and BMP15 expression in the cumulus cells (0 ± 0.16 and 0 ± 0.07) and oocytes (1.47 ± 0.07 and 1.32 ± 0.03) was lowest (P ≤ 0.05) in the in vivo grown antral follicles. In the cultured follicles, the stage-specific undulations observed in the expression of GDF9 and BMP15 in the in vivo grown follicles were either different or abolished. For example, in the oocytes from in vitro grown follicles, the expression of BMP15 did not change as the development progressed all the way from preantral to large antral follicle stage although in the oocytes from in vivo grown follicles BMP15 expression exhibited stage-specific variations. It is concluded that GDF9 and BMP15 follow a stage-specific pattern of expression during the in vivo development of ovarian follicles in sheep, and in vitro culture altered the stage-specific changes in the expression of these two genes. Copyright © 2016 Elsevier Inc. All rights reserved.

The culture of chick embryo mesoderm cells in hydrated collagen gels.

PubMed

Sanders, E J; Prasad, S

1983-04-01

Chick embryo mesoderm cells are various stages of differentiation were cultured in three-dimensional matrices of hydrated collagen. The tissues used were: stage 5 mesoderm from regions adjacent to the primitive streak; stage 12 mesoderm, comprising somitic, unsegmented (segmental plate) and lateral plate mesoderm; and stage 18 sclerotome. Explants were examined by phase contrast microscopy, including time-lapse, and scanning and transmission electron microscopy. The cells showed an increased ability to adhere to, and move in, the collagen gel with advancing stage. Of the stage 12 tissues, the unsegmented mesoderm was initially the slowest to grow out of the explant. Sclerotome cells showed by far the greatest ability to move within the gel. Where the collagen fibrils were randomly oriented, the cell morphology was polypodial and advancing lamellipodia showed clear undulations at their leading edges. A distinction was drawn between these undulations and the classical major ruffles which are seen in two-dimensional culture to uplift and pass back along the cell surface. The latter were not seen in the collagen matrix and were presumably suppressed by the three-dimensional culture configuration while the leading edge undulations were not. Ultrastructural examination showed that the cells possessed patches of amorphous material on their surface, which was sometimes interposed between the plasma membrane and collagen fibrils. Addition of hyaluronic acid (2 mg/ml) had an effect only the segmented mesoderm, where outgrowth was enhanced. Although the addition of plasma fibronectin (50 micrograms/ml) to the cultures did not affect any of the tissues, the removal of this substance, by antifibronectin antiserum or by the use of fibronectin depleted serum, inhibited outgrowth in most cases. The only tissue not reproducibly inhibited in this way was sclerotome. Alignment of the collagen fibres by the explants was observed, accompanied by an elongation of the outgrowing cells which, in bipolar form, preferentially moved up and down the aligned tracts. Scanning electron microscopy suggested that cell processes attached to, and presumably exerted tension on, bundles of fibrils thereby pulling them into line. Cell-to-cell contact was not accompanied by contact paralysis as judged by time-lapse micrography.

Atomization of Wall-Bounded Two-Phase Flows (Preprint)

DTIC Science & Technology

2006-11-07

are given in Fig. 2. In the Rayleigh mode hydrodynamic instabilities produced by surface tension cause the jet surface to undulate [16]. Eventually...18], hydrodynamic instabilities [16] or the interaction of vortices in the gas phase [19]. Various mechanisms, discussed in the Atomization...width of the leading edge of the sheet. This regime is analogous to the Rayleigh mode in jets— hydrodynamic instabilities cause the surface of the

Advanced Photon Source accelerator ultrahigh vacuum guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C.; Noonan, J.

1994-03-01

In this document the authors summarize the following: (1) an overview of basic concepts of ultrahigh vacuum needed for the APS project, (2) a description of vacuum design and calculations for major parts of APS, including linac, linac waveguide, low energy undulator test line, positron accumulator ring (PAR), booster synchrotron ring, storage ring, and insertion devices, and (3) cleaning procedures of ultrahigh vacuum (UHV) components presently used at APS.

Novel Out-Coupling Techniques for Terahertz Free Electron Lasers

DTIC Science & Technology

2012-06-01

4  1.   FEL “ Pendulum ” Equation and Electron Dynamics .......................4  2.   FEL...4 B. FEL THEORY 1. FEL “ Pendulum ” Equation and Electron Dynamics The dynamics of electron motion as it passes through the undulator are governed...I.5, then the FEL “ pendulum equation” is derived , (I.7) where is the dimensionless laser field amplitude[1]. From this, it is shown that changes

Coherent emission from a bunched electron beam: superradiance and stimulated-superradiance in a uniform and tapered wiggler FEL

NASA Astrophysics Data System (ADS)

Gover, A.; Ianconescu, R.; Friedman, A.; Emma, C.; Musumeci, P.

2017-09-01

We outline fundamental coherent radiation processes from a charge particles beam: Spontaneous Superradiance (SR), Stimulated Superradiance (ST-SR), and in the context of undulator radiation: Tapering-Enhanced Superradiance (TES) and Tapering-Enhanced Stimulated Superradiance Amplification (TESSA). Both single bunch and periodic bunching (in phasor and spectral Fourier frequency formulations) are considered in a model of radiation mode expansion.

The CSU Accelerator and FEL Facility

NASA Astrophysics Data System (ADS)

Biedron, Sandra; Milton, Stephen; D'Audney, Alex; Edelen, Jonathan; Einstein, Josh; Harris, John; Hall, Chris; Horovitz, Kahren; Martinez, Jorge; Morin, Auralee; Sipahi, Nihan; Sipahi, Taylan; Williams, Joel

2014-03-01

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode drive linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Details of the systems used in CSU Accelerator Facility are discussed.

Characteristics of a Direct-Seeded Eastern White Pine Plantation on the Mid-Cumberland Plateau at Four Ages

Treesearch

Glendon W. Smalley; James M. Hollingsworth

1997-01-01

Growth and yield of a direct-seeded eastern white pine (Pinus strobus L.) plantation established in 1959 on a broad undulating sandstone upland (Landtype 1) are summarized. Average heights of dominant and codominant pines were 35,56,65, and 76 ft at ages 15,25,30, and 34 years, respectively. Equivalent site indices (base age 25 years from seed)...

Developments in Polarization and Energy Control of APPLE-II Undulators at Diamond Light Source

NASA Astrophysics Data System (ADS)

Longhi, E. C.; Bencok, P.; Dobrynin, A.; Rial, E. C. M.; Rose, A.; Steadman, P.; Thompson, C.; Thomson, A.; Wang, H.

2013-03-01

A pair of 2m long APPLE-II type undulators have been built for the I10 BLADE beamline at Diamond Light Source. These 48mm period devices have gap as well as four moveable phase axes which provide the possibility to produce the full range of elliptical polarizations as well as linear polarization tilted through a full 180deg. The mechanical layout chosen has a 'master and slave' arrangement of the phase axes on the top and bottom. This arrangement allows the use of symmetries to provide operational ease for both changing energy using only the master phase while keeping fixed linear horizontal or circular polarization, as well as changing linear polarization angle while keeping fixed energy [1]. The design allows very fast motion of the master phase arrays, without sacrifice of accuracy, allowing the possibility of mechanical polarization switching at 1Hz for dichroism experiments. We present the mechanical design features of these devices, as well as the results of magnetic measurements and shimming from before installation. Finally, we present the results of characterization of these devices by the beamline, including polarimetry, which has been done on the various modes of motion to control energy and polarization. These modes of operation have been available to users since 2011.

Progress on the Development of the Next Generation X-ray Beam Position Monitors at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S.H.; Yang, B.X.; Decker, G.

Accurate and stable x-ray beam position monitors (XBPMs) are ke y elements in obtaining the desired user beam stability in the Advanced Photon Source (APS). The next generat ion XBPMs for high heat load front ends (HHL FEs) have been designed to meet these requirements by utilizing Cu K-edge x-ray fluorescence (XRF) from a pair of copper absorbers and have been installed at the front ends (FEs) of the APS. Com missioning data showed a significant performance improvement over the existing photoemission-based XBPMs. While a similar design concept can be applied for the canted undulator front ends, where two undulatormore » beams are separated by 1.0-mrad, the lower beam power (< 10 kW) per undulator allows us to explore lower-cost solutions based on Compton scat tering from the diamond blades placed edge-on to the x- ray beam. A prototype of the Compton scattering XBPM system was i nstalled at 24-ID-A in May 2015. In this report, the design and test results for XRF-based XBPM and Compton scattering based XBPM are presented. Ongoing research related to the development of the next generation XBPMs on thermal contac t resistance of a joint between two solid bodies is also discussed« less

Doubling The Intensity Of An ERL Based Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrew Hutton

2005-05-01

A light source based on an Energy Recovered Linac (ERL) [1] consists of a superconducting linac and a transfer line that includes wigglers and undulators to produce the synchrotron light. The transfer line brings the electron bunches back to the beginning of the linac so that their energy can be recovered when they traverse the linac a second time, {lambda}/2 out of RF phase. There is another interesting condition when the length of the transfer line is (n {+-} 1/4) {lambda}. In this case, the electrons drift through on the zero RF crossing, and make a further pass around themore » transfer line, effectively doubling the circulating current in the wigglers and undulators. On the third pass through the linac, they will be decelerated and their energy recovered. The longitudinal focusing at the zero crossing is a problem, but it can be canceled if the drifting beam sees a positive energy gradient for the first half of the linac and a negative gradient for the second half (or vice versa). This paper presents a proposal to use a double chicane at the center of the linac to provide this focusing inversion for the drifting beam while leaving the accelerating and decelerating beams on crest. [1] G. R. Neil, et al, Phys. Rev. Let. 84, 662 2000« less

Insertion devices for DORIS III (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pflueger, J.

1992-01-01

Recently, a major reconstruction of the electron storage ring DORIS II, the DORIS III project, has been completed (W. Brefeld, H. Nesemann, and J. Rossbach, {ital Proceedings} {ital of} {ital the} {ital European} {ital Particle} {ital Accelerator} {ital Conference}, Rome (World Scientific, Singapore, 1988), p. 2389). Figure 1 shows an overview of the new ring. Originally DORIS II had a twofold symmetry. In part C each of the two dipole magnets adjacing to the 65-m-long straight section was replaced by three corresponding weaker ones. In this way a total of seven straight sections for insertion devices are provided. Six ofmore » them are 4-m long and the one in the center is only 2.7-m long. After extensive discussions with the user groups involved, four x-ray wigglers, one asymmetric hybrid structure, one x-ray undulator, and one XUV multiple undulator of the revolver type have been proposed for six of the sections (J. Pflueger and P. Gurtler, Nucl. Instrum. Methods A {bold 287}, 628 (1990)). One section is presently still free. All devices are either in construction or have already been completed and installed. In this contribution the mechanical and magnetic design of these devices will be described. Results of magnetic measurements of those devices which are already completed will be given in more detail.« less

The microjet-film interaction: the interaction and resulting shapes of a liquid microjet impacting a soap film

NASA Astrophysics Data System (ADS)

Chan, Jau Tung; Lee, Jie Liang; Tjeng, Vincent; Yeo, Ye; Tan, Guoxian

2014-11-01

The International Young Physicists’ Tournament (IYPT) is a worldwide annual competition for high-school students. This paper is adapted from the solution to problem 8, Jet and Film, as presented by the Singapore Team at the 26th IYPT, Taipei, Taiwan. The impact of liquid microjets on stable soap films was investigated. Two steady regimes were observed: refraction (where the microjet penetrates the soap film and is deflected) and absorption (where the microjet merges with the soap film and forms vertical undulating patterns on the soap film surface). This phenomenon has potential applications in controlling the trajectory of a liquid microjet in air. Although Kirstetter et al (2012) investigated this interaction by using the same liquid for both the microjet and the soap film, this paper extends their work by using different liquids for the microjet and the soap film. In addition, the need for a small-angle approximation of Snell’s law is removed for the refraction regime, and an alternative expression is proposed for the force exerted by the soap film on the microjet in the absorption regime that accounts for the dependence of the wavelength of the undulating patterns on the angle of incidence of the microjet on the soap film. Empirical data support these improved theoretical predictions.

Plasma inverse transition acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Ming

It can be proved fundamentally from the reciprocity theorem with which the electromagnetism is endowed that corresponding to each spontaneous process of radiation by a charged particle there is an inverse process which defines a unique acceleration mechanism, from Cherenkov radiation to inverse Cherenkov acceleration (ICA) [1], from Smith-Purcell radiation to inverse Smith-Purcell acceleration (ISPA) [2], and from undulator radiation to inverse undulator acceleration (IUA) [3]. There is no exception. Yet, for nearly 30 years after each of the aforementioned inverse processes has been clarified for laser acceleration, inverse transition acceleration (ITA), despite speculation [4], has remained the least understood,more » and above all, no practical implementation of ITA has been found, until now. Unlike all its counterparts in which phase synchronism is established one way or the other such that a particle can continuously gain energy from an acceleration wave, the ITA to be discussed here, termed plasma inverse transition acceleration (PITA), operates under fundamentally different principle. As a result, the discovery of PITA has been delayed for decades, waiting for a conceptual breakthrough in accelerator physics: the principle of alternating gradient acceleration [5, 6, 7, 8, 9, 10]. In fact, PITA was invented [7, 8] as one of several realizations of the new principle.« less

Harbor seal vibrissa morphology suppresses vortex-induced vibrations.

PubMed

Hanke, Wolf; Witte, Matthias; Miersch, Lars; Brede, Martin; Oeffner, Johannes; Michael, Mark; Hanke, Frederike; Leder, Alfred; Dehnhardt, Guido

2010-08-01

Harbor seals (Phoca vitulina) often live in dark and turbid waters, where their mystacial vibrissae, or whiskers, play an important role in orientation. Besides detecting and discriminating objects by direct touch, harbor seals use their whiskers to analyze water movements, for example those generated by prey fish or by conspecifics. Even the weak water movements left behind by objects that have passed by earlier can be sensed and followed accurately (hydrodynamic trail following). While scanning the water for these hydrodynamic signals at a swimming speed in the order of meters per second, the seal keeps its long and flexible whiskers in an abducted position, largely perpendicular to the swimming direction. Remarkably, the whiskers of harbor seals possess a specialized undulated surface structure, the function of which was, up to now, unknown. Here, we show that this structure effectively changes the vortex street behind the whiskers and reduces the vibrations that would otherwise be induced by the shedding of vortices from the whiskers (vortex-induced vibrations). Using force measurements, flow measurements and numerical simulations, we find that the dynamic forces on harbor seal whiskers are, by at least an order of magnitude, lower than those on sea lion (Zalophus californianus) whiskers, which do not share the undulated structure. The results are discussed in the light of pinniped sensory biology and potential biomimetic applications.

EPICS controlled sample mounting robots at the GM/CA CAT.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makarov, O. A.; Benn, R.; Corcoran, S.

2007-11-11

GM/CA CAT at Sector 23 of the advanced photon source (APS) is an NIH funded facility for crystallographic structure determination of biological macromolecules by X-ray diffraction [R.F. Fischetti, et al., GM/CA canted undulator beamlines for protein crystallography, Acta Crystallogr. A 61 (2005) C139]. The facility consists of three beamlines; two based on canted undulators and one on a bending magnet. The scientific and technical goals of the CAT emphasize streamlined, efficient throughput for a variety of sample types, sizes and qualities, representing the cutting edge of structural biology research. For this purpose all three beamlines are equipped with the ALS-stylemore » robots [C.W.Cork, et al. Status of the BCSB automated sample mounting and alignment system for macromolecular crystallography at the Advanced Light Source, SRI-2003, San-Francisco, CA, USA, August 25-29, 2003] for an automated mounting of cryo-protected macromolecular crystals. This report summarizes software and technical solutions implemented with the first of the three operational robots at beamline 23-ID-B. The automounter's Dewar can hold up to 72 or 96 samples residing in six Rigaku ACTOR magazines or ALS-style pucks, respectively. Mounting of a crystal takes approximately 2 s, during which time the temperature of the crystal is maintained near that of liquid nitrogen.« less

Impact of Nasser Lake on gravity reduction and geoidal heights for Egypt

NASA Astrophysics Data System (ADS)

Abd-Elmotaal, Hussein A.; Makhloof, Atef; Hassan, Ayman; Ashry, Mostafa

2018-06-01

In the course of the IAG African Geoid Project, it is needed to study the impact of the lakes on the gravity reduction and geoidal heights. The aim of this paper is to study the impact of the water in Nasser Lake on gravity reduction and geoidal heights for Egypt. The determination of the gravimetric geoid is based on the well-known remove-restore technique. The problem of the lakes occurs because the popular programs widely used in practice (e.g., TC-program (Forsberg, 1984)) assume that all positive elevations are filled with rock topography, and all negative elevations are filled with ocean water. This is, however, not true for the case of Nasser Lake, which lies completely above sea level, at about 180 m elevation, with a water depth of about 20 m. The paper presents an approach on estimating the impact of Nasser Lake on gravity reduction and geoidal heights using TC-program with some tricky cases. The results show that the impact of Nasser Lake on both gravity anomalies and geoid undulation is limited to the area of the lake. The impact of Nasser Lake on the gravity anomalies is in the order of sub mgal, while the impact of Nasser lake on the geoid undulation is significant and reaches few centimeters.

Epidemiology of vampire bat-transmitted rabies virus in Goiás, central Brazil: re-evaluation based on G-L intergenic region

PubMed Central

2010-01-01

Background Vampire bat related rabies harms both livestock industry and public health sector in central Brazil. The geographical distributions of vampire bat-transmitted rabies virus variants are delimited by mountain chains. These findings were elucidated by analyzing a high conserved nucleoprotein gene. This study aims to elucidate the detailed epidemiological characters of vampire bat-transmitted rabies virus by phylogenetic methods based on 619-nt sequence including unconserved G-L intergenic region. Findings The vampire bat-transmitted rabies virus isolates divided into 8 phylogenetic lineages in the previous nucleoprotein gene analysis were divided into 10 phylogenetic lineages with significant bootstrap values. The distributions of most variants were reconfirmed to be delimited by mountain chains. Furthermore, variants in undulating areas have narrow distributions and are apparently separated by mountain ridges. Conclusions This study demonstrates that the 619-nt sequence including G-L intergenic region is more useful for a state-level phylogenetic analysis of rabies virus than the partial nucleoprotein gene, and simultaneously that the distribution of vampire bat-transmitted RABV variants tends to be separated not only by mountain chains but also by mountain ridges, thus suggesting that the diversity of vampire bat-transmitted RABV variants was delimited by geographical undulations. PMID:21059233

Characterization of the X-ray coherence properties of an undulator beamline at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ju, Guangxu; Highland, Matthew J.; Thompson, Carol

In anticipation of the increased use of coherent X-ray methods and the need to upgrade beamlines to match improved source quality, here the coherence properties of the X-rays delivered by beamline 12ID-D at the Advanced Photon Source have been characterized. The measured X-ray divergence, beam size, brightness and coherent flux at energies up to 26 keV are compared with the calculated values from the undulator source, and the effects of beamline optics such as a mirror, monochromator and compound refractive lenses are evaluated. Diffraction patterns from slits as a function of slit width are analyzed using wave propagation theory tomore » obtain the beam divergence and thus coherence length. Imaging of the source using a compound refractive lens was found to be the most accurate method for determining the vertical divergence. While the brightness and coherent flux obtained without a monochromator ('pink beam') agree well with those calculated for the source, those measured with the monochromator were a factor of three to six lower than the source, primarily because of vertical divergence introduced by the monochromator. As a result, the methods described herein should be widely applicable for measuring the X-ray coherence properties of synchrotron beamlines.« less

Characterization of the X-ray coherence properties of an undulator beamline at the Advanced Photon Source

DOE PAGES

Ju, Guangxu; Highland, Matthew J.; Thompson, Carol; ...

2018-06-13

In anticipation of the increased use of coherent X-ray methods and the need to upgrade beamlines to match improved source quality, here the coherence properties of the X-rays delivered by beamline 12ID-D at the Advanced Photon Source have been characterized. The measured X-ray divergence, beam size, brightness and coherent flux at energies up to 26 keV are compared with the calculated values from the undulator source, and the effects of beamline optics such as a mirror, monochromator and compound refractive lenses are evaluated. Diffraction patterns from slits as a function of slit width are analyzed using wave propagation theory tomore » obtain the beam divergence and thus coherence length. Imaging of the source using a compound refractive lens was found to be the most accurate method for determining the vertical divergence. While the brightness and coherent flux obtained without a monochromator ('pink beam') agree well with those calculated for the source, those measured with the monochromator were a factor of three to six lower than the source, primarily because of vertical divergence introduced by the monochromator. As a result, the methods described herein should be widely applicable for measuring the X-ray coherence properties of synchrotron beamlines.« less

CVD-diamond-based position sensitive photoconductive detector for high-flux x-rays and gamma rays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu, D.

1999-04-19

A position-sensitive photoconductive detector (PSPCD) using insulating-type CVD diamond as its substrate material has been developed at the Advanced Photon Source (APS). Several different configurations, including a quadrant pattern for a x-ray-transmitting beam position monitor (TBPM) and 1-D and 2-D arrays for PSPCD beam profilers, have been developed. Tests on different PSPCD devices with high-heat-flux undulator white x-ray beam, as well as with gamma-ray beams from {sup 60}Co sources have been done at the APS and National Institute of Standards and Technology (NIST). It was proven that the insulating-type CVD diamond can be used to make a hard x-ray andmore » gamma-ray position-sensitive detector that acts as a solid-state ion chamber. These detectors are based on the photoconductivity principle. A total of eleven of these TBPMs have been installed on the APS front ends for commissioning use. The linear array PSPCD beam profiler has been routinely used for direct measurements of the undulator white beam profile. More tests with hard x-rays and gamma rays are planned for the CVD-diamond 2-D imaging PSPCD. Potential applications include a high-dose-rate beam profiler for fourth-generation synchrotrons radiation facilities, such as free-electron lasers.« less

Scaling the Thrust Production and Energetics of Inviscid Intermittent Swimming

NASA Astrophysics Data System (ADS)

Akoz, Emre; Moored, Keith

2015-11-01

Many fish have adopted an intermittent swimming gait sometimes referred as a burst-and-coast behavior. By using this gait, fish have been estimated at reducing their energetic cost of swimming by about 50%. Lighthill proposed that the skin friction drag of an undulating body can be around 400% greater than a rigidly-held coasting body, which may explain the energetic savings of intermittent swimming. Recent studies have confirmed the increase in skin friction drag over an undulating body, however, the increase is on the order of 20-70%. This more modest gain in skin friction drag is not sufficient to lead to the observed energy savings. Motivated by these observations, we investigate the inviscid mechanisms behind intermittent swimming for parameters typical of biology. We see that there is an energy savings at a fixed swimming speed for intermittent swimming as compared to continuous swimming. Then we consider three questions: What is the nature of the inviscid mechanism that leads to the observed energy savings, how do the forces and energetics of intermittent swimming scale with the swimming parameters, and what are the limitations to the benefit? Supported by the Office of Naval Research under Program Director Dr. Bob Brizzola, MURI grant number N00014-14-1-0533.

OPERATIONAL EXPERIENCE WITH FAST FIBER-OPTIC BEAM LOSS MONITORS FOR THE ADVANCED PHOTON SOURCE STORAGE RING SUPERCONDUCTING UNDULATORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dooling, J.; Harkay, K.; Sajaev, V.

Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-mlong SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016more » and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps [1] by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.« less

Characteristics of undulatory locomotion in granular media

NASA Astrophysics Data System (ADS)

Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn J.

2016-03-01

Undulatory locomotion is ubiquitous in nature and observed in different media, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Despite the similarity in the undulating pattern, the swimming characteristics depend on the rheological properties of different media. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but recently a resistive force theory in granular media has been proposed and shown useful in studying the locomotion of a sand-swimming lizard. Here we employ the proposed model to investigate the swimming characteristics of a slender filament, of both finite and infinite length, undulating in a granular medium and compare the results with swimming in viscous fluids. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. We also find that, similar to Lighthill's results using resistive force theory in viscous fluids, the sawtooth swimmer is the optimal waveform for propulsion speed at a given power consumption in granular media. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

The significance of pre-existing, deeply weathered crystalline rock in interpreting the effects of glaciation in the Minnesota River valley, U.S.A.

USGS Publications Warehouse

Patterson, C.J.; Boerboom, Terrence

1999-01-01

Minnesota is largely underlain by Precambrian crystalline bedrock that was weathered to an average depth of 30 m prior to Late Cretaceous time. The fresh-rock-weathered-rock interface is irregular, with as much as 45 m of relief. Weathering exploited joints, locally isolating meter-sized volumes of rock known as corestones. Variable amounts of residuum were removed through glaciation to leave (1) saprolite overlain by an in-situ Late Cretaceous soil profile; (2) partially eroded saprolite; and (3) undulating fresh rock surfaces (commonly mantled by rounded boulders) that display striae and glacial or fluvial polish. Significant subglacial erosion of fresh bedrock is not required to form smoothly undulating bedrock surfaces with closed depressions; they may also form through removal of weathered bedrock and exposure of the weathering front. Large rounded boulders are not always shaped during transport; they may represent chemically rounded corestones resting at or near the bedrock source. Unambiguous evidence for glacial erosion includes striae and streamlining of bedrock parallel to striae. Polish on rock can be created fluvially, and smoothed grooves and ridges in the rock may be chemically produced. Many rounded boulders found in glacial till and strewn on bedrock surfaces probably originated as corestones.

Responsive 3D microstructures from virus building blocks.

PubMed

Oh, Seungwhan; Kwak, Eun-A; Jeon, Seongho; Ahn, Suji; Kim, Jong-Man; Jaworski, Justyn

2014-08-13

Fabrication of 3D biological structures reveals dynamic response to external stimuli. A liquid-crystalline bridge extrusion technique is used to generate 3D structures allowing the capture of Rayleigh-like instabilities, facilitating customization of smooth, helical, or undulating periodic surface textures. By integrating intrinsic biochemical functionality and synthetic components into controlled structures, this strategy offers a new form of adaptable materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trypanosoma evansi isolated from capybara (Hidrochaeris hidrochaeris).

PubMed

Muñoz, K; Chávez, A

2001-10-01

A study was conducted to determine the morphological and biometric characteristics of Trypanosoma isolated from 50 capybaras animals, raised in captivity in the Peruvian Amazon. Trypanosoma was found in 14 blood samples using the microhaematocrit, wide drop, and Giemsa-stain methods and T. evansi was identified through morphological details in all 14 positive samples (the subterminal kinetoplast, the developed undulating membrane, and a long free flagellum were used for the identification of the agent).

FAST TRACK COMMUNICATION: Stable propagation of a modulated positron beam in a bent crystal channel

NASA Astrophysics Data System (ADS)

Kostyuk, A.; Korol, A. V.; Solov'yov, A. V.; Greiner, W.

2010-08-01

The propagation of a modulated positron beam in a planar crystal channel is investigated. It is demonstrated that the beam preserves its modulation at sufficiently large penetration depths, which opens the prospect of using a crystalline undulator as a coherent source of hard x-rays. This finding is a crucial milestone in developing a new type of laser radiating in the hard x-ray and gamma-ray range.

Multiphase flow in geometrically simple fracture intersections

USGS Publications Warehouse

Basagaoglu, H.; Meakin, P.; Green, C.T.; Mathew, M.; ,

2006-01-01

A two-dimensional lattice Boltzmann (LB) model with fluid-fluid and solid-fluid interaction potentials was used to study gravity-driven flow in geometrically simple fracture intersections. Simulated scenarios included fluid dripping from a fracture aperture, two-phase flow through intersecting fractures and thin-film flow on smooth and undulating solid surfaces. Qualitative comparisons with recently published experimental findings indicate that for these scenarios the LB model captured the underlying physics reasonably well.

Generation and characterization of ultra-short electron beams for single spike infrared FEL radiation at SPARC_LAB

NASA Astrophysics Data System (ADS)

Villa, F.; Anania, M. P.; Artioli, M.; Bacci, A.; Bellaveglia, M.; Bisesto, F. G.; Biagioni, A.; Carpanese, M.; Cardelli, F.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Ciocci, F.; Croia, M.; Curcio, A.; Dattoli, G.; Gallo, A.; Di Giovenale, D.; Di Palma, E.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Giannessi, L.; Giribono, A.; Marocchino, A.; Massimo, F.; Mostacci, A.; Petralia, A.; Petrarca, M.; Petrillo, V.; Piersanti, L.; Pioli, S.; Pompili, R.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.

2017-09-01

The technique for producing and measuring few tens of femtosecond electron beams, and the consequent generation of few tens femtoseconds single spike FEL radiation pulses at SPARC_LAB is presented. The undulator has been used in the double role of radiation source and diagnostic tool for the characterization of the electron beam. The connection between the electron bunch length and the radiation bandwidth is analyzed.

Biologically Based Undulatory Lamprey Auv Project.

DTIC Science & Technology

1995-01-01

flexibility of a fish body depends on the axial skeleton which in some fish con- sists of the bony vertebra column whereas in others it consists of notochord ...undulations and peristaltics to the almost hydrostatic notochord of amphioxus. The latter can change its stiffness by the activation of muscle fibers...paramyosine) lying inside the notochord . The notochord lies along the central axis of the body, contains no bone, and takes up approximately 7% - 10

Characterization of the Effect of Fiber Undulation on Strength and Stiffness of Composite Laminates

DTIC Science & Technology

2015-03-01

helicopter drivelines with flexible matrix composite shafting. Proceedings of the 61st American Helicopter Society Annual Forum; 2005 Jun 1–3...Grapevine, TX. Alexandria (VA): American Helicopter Society. p. 1582–1595. 2. Hannibal AJ, Gupta BP, Avila JA, Parr CH. Flexible matrix composites applied...to bearingless rotor system. Journal of the American Helicopter Society. 1985;30(1):21–27. 3. Ocalan M. High flexibility rotorcraft driveshafts

Safe Inner Ear Gas Tensions for Switch from Helium to Air Breathing During Decompression

DTIC Science & Technology

2013-04-01

heliox to air during decompression is that it is associated with symptoms of injury to the vestibulocochlear apparatus (inner ear) such as vertigo ...dive. Vertigo , nausea, and other symptoms consistent with injury to the vestibulocochlear apparatus have been described during 1200 feet sea water (fsw...and undulating nausea. No other symptoms. No numbness, tingling, weakness or vertigo . Symptoms attributed to large amount of food <supplied>cold pizza

(2E)-3-[4-(Benz-yloxy)phen-yl]-1-(2,6-dichloro-3-fluoro-phen-yl)prop-2-en-1-one.

PubMed

Praveen, Aletti S; Yathirajan, Hemmige S; Gerber, Thomas; van Brecht, Benjamin; Betz, Richard

2012-12-01

In the title compound, C22H15Cl2FO2, a chalcone derivative featuring a threefold-halogenated aromatic substituent, the conformation about the C=C bond is E. In the crystal C-H⋯F and C-H⋯Cl contacts connect the mol-ecules into undulating sheets parallel to (101). In addition, C-H⋯π inter-actions are also present.

Harmonic lasing in x-ray free electron lasers

NASA Astrophysics Data System (ADS)

Schneidmiller, E. A.; Yurkov, M. V.

2012-08-01

Harmonic lasing in a free electron laser with a planar undulator (under the condition that the fundamental frequency is suppressed) might be a cheap and efficient way of extension of wavelength ranges of existing and planned x-ray free electron laser (FEL) facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental frequency. In this paper we perform a parametrization of the solution of the eigenvalue equation for lasing at odd harmonics, and present an explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental harmonic. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of x-ray beam at saturation. Considering 3rd harmonic lasing as a practical example, we come to the conclusion that it is much more robust than usually thought, and can be widely used in the existing or planned x-ray FEL (XFEL) facilities. In particular, Linac Coherent Light Source (LCLS) after a minor modification can lase to saturation at the 3rd harmonic up to the photon energy of 25-30 keV providing multigigawatt power level and narrow bandwidth. As for the European XFEL, harmonic lasing would allow one to extend operating range (ultimately up to 100 keV), to reduce FEL bandwidth and to increase brilliance, to enable two-color operation for pump-probe experiments, and to provide more flexible operation at different electron energies. Similar improvements can be realized in other x-ray FEL facilities with gap-tunable undulators like FLASH II, SACLA, LCLS II, etc. Harmonic lasing can be an attractive option for compact x-ray FELs (driven by electron beams with a relatively low energy), allowing the use of the standard undulator technology instead of small-gap in-vacuum devices. Finally, in this paper we discover that in a part of the parameter space, corresponding to the operating range of soft x-ray beam lines of x-ray FEL facilities (like SASE3 beam line of the European XFEL), harmonics can grow faster than the fundamental wavelength. This feature can be used in some experiments, but might also be an unwanted phenomenon, and we discuss possible measures to diminish it.

The first insertion devices at SSRL - some personal recollections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winick, H.

1995-02-01

The author recounts his experiences with insertion devices at the Stanford Synchrotron Radiation Laboratory. His first experiences with wigglers occured at the Cambridge Electron Accelerator, and was carried over to SSRL with the proposal for a six pole electromagnetic wiggler. Most modern undulators, and many wigglers are now designed around permanent magnets, and the origin of this transition at SSRL was rather fortuitous and humorous. It reflects some of the personality characteristics of Klaus Halbach.

Saturation Measurements of a Visible SASE FEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, Roger

2002-08-14

VISA (Visible to Infrared SASE Amplifier) is an FEL designed to obtain high gain at a radiation wavelength of 800 nm. Large gain is achieved by driving the FEL with the 71 MeV, high brightness beam of the Accelerator Test Facility (ATF) and using a novel, strong focusing, 4 m long undulator with a gap of 6 mm and a period of 1.8 cm. We report measurements of exponential gain, saturation, and spectra of the FEL radiation intensity.

Final Environmental Assessment (EA) for Headquarters Building Construction and Main Gate Reconfiguration White Bluff, Spokane, Washington

DTIC Science & Technology

2012-12-01

undulating or flat lands covering approximately 62,900 square miles in eastern Washington , western Idaho and northeast Oregon (Tolan et al.1989). Plateau...and thousands of square miles throughout eastern Washington , and pushed the Spokane River north to its present location. Generally, the plateau is...the plateau in eastern Washington (Eliot et al. 1986). The floods scoured the landscape of soil, leaving bare basalt in many areas. Mazama ash and

Mesoscale variability observed in the Northern Adriatic in autumn 2016

NASA Astrophysics Data System (ADS)

Pasaric, Zoran; Iva, Medjugorac; Nastjenka, Supic; Tamara, Djakovac; Mirko, Orlic

2017-04-01

Quasi-synoptic measurements of hydrographic properties were performed in the Northern Adriatic along the transect extending from Rovinj to the Po River mouth in an approximately east-west direction. The depth along the transect slowly varies between 30 and 40 m. Three one-day cruises were conducted, the first on 12 Nov, the second on 18 Nov, and the third on 25 Nov 2016. During the first and the third cruise the sampling was done with a CTD probe lowered from the surface to the bottom, at eleven stations placed nearly equidistantly along the transect. Average distance between the stations was 6 km. The second cruise was conducted with a towed yo-yo profiler equipped with the CTD probe and continuously undulating between the surface and some 4 m above the bottom. With roughly three undulations per kilometer, horizontal resolution along the transect was about 200 m. The data suggest that three processes occurred during the cruises: 1) surface cooling and related vertical mixing, 2) intrusion of high-salinity waters into the western part of the transect, and 3) propagation of a mesoscale formation in a westward direction. The existence and propagation of the mesoscale feature is supported by a simple analytical model of topographic Rossby waves. By assuming that the bottom varies linearly in the direction perpendicular to the transect, the propagation speed of O(1 km/day) is obtained - in agreement with the observations.

The Structural Biology Center 19ID undulator beamline: facility specifications and protein crystallographic results

PubMed Central

Rosenbaum, Gerd; Alkire, Randy W.; Evans, Gwyndaf; Rotella, Frank J.; Lazarski, Krzystof; Zhang, Rong-Guang; Ginell, Stephan L.; Duke, Norma; Naday, Istvan; Lazarz, Jack; Molitsky, Michael J.; Keefe, Lisa; Gonczy, John; Rock, Larry; Sanishvili, Ruslan; Walsh, Martin A.; Westbrook, Edwin; Joachimiak, Andrzej

2008-01-01

The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5–0.6 Å wavelength) with fluxes up to 8–18 × 1012 photons s−1 (depending on photon energy) onto cryogenically cooled crystal samples. The size of the beam (full width at half-maximum) at the sample position can be varied from 2.2 mm × 1.0 mm (horizontal × vertical, unfocused) to 0.083 mm × 0.020 mm in its fully focused configuration. Specimen-to-detector distances of between 100 mm and 1500 mm can be used. The high flexibility, inherent in the design of the optics, coupled with a κ-geometry goniometer and beamline control software allows optimal strategies to be adopted in protein crystallographic experiments, thus maximizing the chances of their success. A large-area mosaic 3 × 3 CCD detector allows high-quality diffraction data to be measured rapidly to the crystal diffraction limits. The beamline layout and the X-ray optical and endstation components are described in detail, and the results of representative crystallographic experiments are presented. PMID:16371706

[Photoeffects, Einstein's light quanta and the history of their acceptance].

PubMed

Wiederkehr, Karl Heinrich

2006-01-01

It is generally supposed, that the discovery of the efficacy-quantum by Planck was the impetus to Einstein's hypothesis of lightquanta. With its help Einstein could explain the external light-electrical effect. But even years before Einstein had worked at the photoeffect and already made experiments on it. For that reason the article gives a short survey about the history of the lightelectric effects. Lenard's basical work about the release of the photoelectrons is dealt with in detail, without which Einstein would scarcely have found his lightquanta. Furthermore it is shown how difficult it was for the physicists to give up--at least partially--the traditional view of the undulation-nature of light, and how they searched to explain the great energies of the photoelectrons. On the other side it is set forth how Einstein's formula of lightquanta was gradually confirmed. The tragical development of Einstein's personal relations with Johannes Stark and Philipp Lenard are briefly described. Stark was one of the few who supported Einstein's ideas at the beginning. Only with the Compton-effect, which could only be quantitatively interpreted by means of lightquanta and the special theory of relativity 1923, the way was free for the general acceptance of the lightquanta. Einstein did not agree to the obtained dualism of undulation and corpuscle; he had a different solution in mind about the fusion of the two forms of appearance of light.

Status of PLS-II Upgrade Program

NASA Astrophysics Data System (ADS)

Kim, Kyung-Ryul; Wiedemann, Helmut; Park, Sung-Ju; Kim, Dong-Eon; Park, Chong-Do; Park, Sung-Soo; Kim, Seong-Hwan; Kim, Bongsoo; Namkung, Won; Nam, Sanghoon; Ree, Moonhor

2010-06-01

The Pohang Light Source (PLS) at the Pohang Accelerator Laboratory has been operated first at 2.0 GeV since 1995, and later was upgraded to 2.5 GeV. During this time, 6 insertion devices like undulators and multipole wigglers have been put into operation to produce special photon beams, with a total of 27 beamlines installed and 3 beamlines under construction. Recently, Korea synchrotron user's community is demanding high beam stability, higher photon energies as well as more straight sections for insertion devices in the PLS. To meet the user requirements, the PLS-II upgrade program has been launched in January, 2009, incorporating a modified chromatic version of Double Bend Achromat (DBA) to achieve almost twice as many straight sections as the current PLS with a design goal of the relatively low emittance, ɛ, of 5.9 nmṡrad. In the PLS-II, the top-up injection using full energy linac is planned for much higher stable beam as well and thus the production of hard x-ray undulator radiation of 8 to 13 keV is anticipated to allow for the successful research program namely Protein Crystallography. The PLS-II machine components of storage ring, linear accelerator and photon beamlines will be partly dismantled and reinstalled in a 6-months shutdown beginning January, 2011 and then the PLS-II upgrade be started the initial commissioning with a 100 mA beam current from July in 2011.

AN ELECTRON MICROSCOPE STUDY OF SPERMATID DIFFERENTIATION IN THE TOAD, BUFO ARENARUM HENSEL

PubMed Central

Burgos, Mario H.; Fawcett, Don W.

1956-01-01

The differentiation of the spermatids of Bufo arenarum has been described from a study of electron micrographs of thin sections of testis. The development of the acrosome from the Golgi complex takes place in much the same manner as in mammalian spermatogenesis but no acrosome granule is formed. A perforatorium is described for the first time in this species. It is formed by a convergence of dense filaments that arise between the nuclear membrane and the head cap. During maturation of the spermatid the chromatin undergoes striking physicochemical alterations. Fine chromatin granules uniformly dispersed in the karyoplasm are replaced by larger and larger aggregates and these ultimately coalesce to form a very dense sperm head. Two centrioles of cylindrical form are situated very near the base of the sperm head. The longitudinal fibrils of the tail flagellum take origin from one, and the dense fibrous substance of the undulating membrane is closely related to the other. Phase contrast cinematographic observations on the swimming movements of living toad sperm, when considered in relation to the fine structural components of the tail, suggest that there is a contractile component in the undulating membrane as well as in the axial fibrils. The differences in the structure of mammalian and amphibian sperm tails are discussed in relation to differences in the character of their movements. PMID:13331956

The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

NASA Astrophysics Data System (ADS)

Rostamzadeh, N.; Hansen, K. L.; Kelso, R. M.; Dally, B. B.

2014-10-01

Wings with tubercles have been shown to display advantageous loading behavior at high attack angles compared to their unmodified counterparts. In an earlier study by the authors, it was shown that an undulating leading-edge configuration, including but not limited to a tubercled model, induces a cyclic variation in circulation along the span that gives rise to the formation of counter-rotating streamwise vortices. While the aerodynamic benefits of full-span tubercled wings have been associated with the presence of such vortices, their formation mechanism and influence on wing performance are still in question. In the present work, experimental and numerical tests were conducted to further investigate the effect of tubercles on the flow structure over full-span modified wings based on the NACA 0021 profile, in the transitional flow regime. It is found that a skew-induced mechanism accounts for the formation of streamwise vortices whose development is accompanied by flow separation in delta-shaped regions near the trailing edge. The presence of vortices is detrimental to the performance of full-span wings pre-stall, however renders benefits post-stall as demonstrated by wind tunnel pressure measurement tests. Finally, primary and secondary vortices are identified post-stall that produce an enhanced momentum transfer effect that reduces flow separation, thus increasing the generated amount of lift.

Vortex Shedding in the Wake Induced by a Real Elephant Seal Whisker

NASA Astrophysics Data System (ADS)

Turk, Jodi; Omilion, Alexis; Zhang, Wei; Kim, Jeong-Jae; Kim, Jeong-Ju; Choi, Woo-Rak; Lee, Sang-Joon

2017-11-01

Biomimicry has been adopted to create innovative solutions in a vast range of applications. One such application is the design of seal-whisker-inspired flow sensors for autonomous underwater vehicles (AUVs). In dark, cramped, and unstable terrain AUVs are not able to maneuver using visual and sonar-based navigation. Hence, it is critical to use underwater flow sensors to accurately detect minute disturbances in the surroundings. Certain seal whiskers exhibit a unique undulating three-dimensional morphology that can reduce vortex induced vibrations (VIVs) if the major axis of the whisker cross-section is aligned to the inflow. This allows the seal to precisely track prey fish upstream using solely their whiskers. The current study aims to understand the effect of a real seal whisker's morphology on the vortex shedding behavior. Despite extensive studies of wake induced by scaled whisker-like models, the vortex shedding in the wake of a real seal whisker is not well understood. A series of experiments are conducted with a high-speed Particle Imaging Velocimetry (PIV) system in a water channel to examine the vortex shedding downstream from a smooth whisker and an undulating whisker at a Reynolds number of a few hundred. Results of the vortex shedding induced by real seal whiskers can provide insights on developing high-sensitivity underwater flow sensors for AUVs and other whisker-inspired structures.

Spinal projection neurons control turning behaviors in zebrafish.

PubMed

Huang, Kuo-Hua; Ahrens, Misha B; Dunn, Timothy W; Engert, Florian

2013-08-19

Discrete populations of brainstem spinal projection neurons (SPNs) have been shown to exhibit behavior-specific responses during locomotion [1-9], suggesting that separate descending pathways, each dedicated to a specific behavior, control locomotion. In an alternative model, a large variety of motor outputs could be generated from different combinations of a small number of basic motor pathways. We examined this possibility by studying the precise role of ventromedially located hindbrain SPNs (vSPNs) in generating turning behaviors. We found that unilateral laser ablation of vSPNs reduces the tail deflection and cycle period specifically during the first undulation cycle of a swim bout, whereas later tail movements are unaffected. This holds true during phototaxic [10], optomotor [11], dark-flash-induced [12], and spontaneous turns [13], suggesting a universal role of these neurons in controlling turning behaviors. Importantly, we found that the ablation not only abolishes turns but also results in a dramatic increase in the number of forward swims, suggesting that these neurons transform forward swims into turns by introducing turning kinematics into a basic motor pattern of symmetric tail undulations. Finally, we show that vSPN activity is direction specific and graded by turning angle. Together, these results provide a clear example of how a specific motor pattern can be transformed into different behavioral events by the graded activation of a small set of SPNs. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Spinal Projection Neurons Control Turning Behaviors in Zebrafish

PubMed Central

Huang, Kuo-Hua; Ahrens, Misha B.; Dunn, Timothy W.; Engert, Florian

2013-01-01

Summary Discrete populations of brainstem spinal projection neurons (SPNs) have been shown to exhibit behavior-specific responses during locomotion [1–9], suggesting that separate descending pathways, each dedicated to a specific behavior, control locomotion. In an alternative model, a large variety of motor outputs could be generated from different combinations of a small number of basic motor pathways. We examined this possibility by studying the precise role of ventromedially located hindbrain SPNs (vSPNs) in generating turning behaviors. We found that unilateral laser ablation of vSPNs reduces the tail deflection and cycle period specifically during the first undulation cycle of a swim bout, whereas later tail movements are unaffected. This holds true during phototaxic [10], optomotor [11], dark-flash-induced [12], and spontaneous turns [13], suggesting a universal role of these neurons in controlling turning behaviors. Importantly, we found that the ablation not only abolishes turns but also results in a dramatic increase in the number of forward swims, suggesting that these neurons transform forward swims into turns by introducing turning kinematics into a basic motor pattern of symmetric tail undulations. Finally, we show that vSPN activity is direction specific and graded by turning angle. Together, these results provide a clear example of how a specific motor pattern can be transformed into different behavioral events by the graded activation of a small set of SPNs. PMID:23910662

Tunable nano-wrinkling of chiral surfaces: Structure and diffraction optics

NASA Astrophysics Data System (ADS)

Rofouie, P.; Pasini, D.; Rey, A. D.

2015-09-01

Periodic surface nano-wrinkling is found throughout biological liquid crystalline materials, such as collagen films, spider silk gland ducts, exoskeleton of beetles, and flower petals. These surface ultrastructures are responsible for structural colors observed in some beetles and plants that can dynamically respond to external conditions, such as humidity and temperature. In this paper, the formation of the surface undulations is investigated through the interaction of anisotropic interfacial tension, swelling through hydration, and capillarity at free surfaces. Focusing on the cellulosic cholesteric liquid crystal (CCLC) material model, the generalized shape equation for anisotropic interfaces using the Cahn-Hoffman capillarity vector and the Rapini-Papoular anchoring energy are applied to analyze periodic nano-wrinkling in plant-based plywood free surfaces with water-induced cholesteric pitch gradients. Scaling is used to derive the explicit relations between the undulations' amplitude expressed as a function of the anchoring strength and the spatially varying pitch. The optical responses of the periodic nano-structured surfaces are studied through finite difference time domain simulations indicating that CCLC surfaces with spatially varying pitch reflect light in a wavelength higher than that of a CCLC's surface with constant pitch. This structural color change is controlled by the pitch gradient through hydration. All these findings provide a foundation to understand structural color phenomena in nature and for the design of optical sensor devices.

The small molecule Mek1/2 inhibitor U0126 disrupts the chordamesoderm to notochord transition in zebrafish.

PubMed

Hawkins, Thomas A; Cavodeassi, Florencia; Erdélyi, Ferenc; Szabó, Gábor; Lele, Zsolt

2008-04-17

Key molecules involved in notochord differentiation and function have been identified through genetic analysis in zebrafish and mice, but MEK1 and 2 have so far not been implicated in this process due to early lethality (Mek1-/-) and functional redundancy (Mek2-/-) in the knockout animals. Here, we reveal a potential role for Mek1/2 during notochord development by using the small molecule Mek1/2 inhibitor U0126 which blocks phosphorylation of the Mek1/2 target gene Erk1/2 in vivo. Applying the inhibitor from early gastrulation until the 18-somite stage produces a specific and consistent phenotype with lack of dark pigmentation, shorter tail and an abnormal, undulated notochord. Using morphological analysis, in situ hybridization, immunhistochemistry, TUNEL staining and electron microscopy, we demonstrate that in treated embryos the chordamesoderm to notochord transition is disrupted and identify disorganization in the medial layer of the perinotochordal basement mebrane as the probable cause of the undulations and bulges in the notochord. We also examined and excluded FGF as the upstream signal during this process. Using the small chemical U0126, we have established a novel link between MAPK-signaling and notochord differentiation. Our phenotypic analysis suggests a potential connection between the MAPK-pathway, the COPI-mediated intracellular transport and/or the copper-dependent posttranslational regulatory processes during notochord differentiation.

User-Friendly End Station at the ALS for Nanostructure Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

F. J. Himpsel; P. Alivisatos; T. Callcott

2006-07-05

This is a construction project for an end station at the ALS, which is optimized for measuring NEXAFS of nanostructures with fluorescence detection. Compared to the usual electron yield detection, fluorescence is able to probe buried structures and is sensitive to dilute species, such as nanostructures supported on a substrate. Since the quantum yield for fluorescence is 10{sup -4}-10{sup -5} times smaller than for electrons in the soft x-ray regime, such an end station requires bright undulator beamlines at the ALS. In order to optimize the setup for a wide range of applications, two end stations were built: (1) Amore » simple, mobile chamber with efficient photon detection (>10{sup 4} times the solid angle collection of fluorescence spectrographs) and a built-in magnet for MCD measurements at EPU beamlines (Fig. 1 left). It allows rapid mapping the electronic states of nanostructures (nanocrystals, nanowires, tailored magnetic materials, buried interfaces, biologically-functionalized surfaces). It was used with BL 8.0 (linear polarized undulator) and BL 4.0 (variable polarization). (2) A sophisticated, stationary end station operating at Beamline 8.0 (Fig. 1 right). It contains an array of surface characterization instruments and a micro-focus capability for scanning across graded samples (wedges for thickness variation, stoichiometry gradients, and general variations of the sample preparation conditions for optimizing nanostructures).« less

A three-dimensional coordination polymer based on 1,2,3-triazole-4,5-dicarboxylic acid (H{sub 3}tda): ([Cd{sub 12}(tda){sub 8}(H{sub 2}O){sub 11}] · (H{sub 2}O)6.25){sub n}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xin-Hui, E-mail: iamxhzhou@njupt.edu.cn; Chen, Qiang

The title coordination polymer ([Cd{sub 12}(tda){sub 8}(H{sub 2}O){sub 11}] · (H{sub 2}O){sub 6.25}){sub n} (H{sub 3}tda = 1,2,3-triazole-4,5-dicarboxylic acid), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex crystallizes in orthorhombic sp. gr. Pmn2{sub 1} with Z = 4. The Cd{sub 2} unit doublebridged by one carboxylate oxygen atom and two neighboring nitrogen atoms from the tda{sup 3–} ligands are linked by the tda{sup 3–}ligands to lead to the 2D (4,4) network in the ac plane. The almost coplanar Cd{sub 2}(μ{sub 5}-tda){sub 2} unit comprised of two Cd ions double-bridged by two tda{sup 3–} ligands through themore » neighboring nitrogen atoms is connected with the other four Cd{sub 2}(μ{sub 5}-tda){sub 2} units form the undulating 2D network in the ac plane. The (4,4) networks and undulating 2D networks are alternatively connected along the b axis by the tda{sup 3–} ligands coordinating to the Cd ions to form the 3D framework.« less

Interfaces in Si/Ge atomic layer superlattices on (001)Si: Effect of growth temperature and wafer misorientation

NASA Astrophysics Data System (ADS)

Baribeau, J.-M.; Lockwood, D. J.; Syme, R. W. G.

1996-08-01

We have used x-ray diffraction, specular reflectivity, and diffuse scattering, complemented by Raman spectroscopy, to study the interfaces in a series of (0.5 nm Ge/2 nm Si)50 atomic layer superlattices on (001)Si grown by molecular beam epitaxy in the temperature range 150-650 °C. X-ray specular reflectivity revealed that the structures have a well-defined periodicity with interface widths of about 0.2-0.3 nm in the 300-590 °C temperature range. Offset reflectivity scans showed that the diffuse scattering peaks at values of perpendicular wave vector transfer corresponding to the superlattice satellite peaks, indicating that the interfaces are vertically correlated. Transverse rocking scans of satellite peaks showed a diffuse component corresponding to an interface corrugation of typical length scale of ˜0.5 μm. The wavelength of the undulations is a minimum along the miscut direction and is typically 30-40 times larger than the surface average terrace width assuming monolayer steps, independently of the magnitude of the wafer misorientation. The amplitude of the undulation evolves with growth temperature and is minimum for growth at ˜460 °C and peaks at ˜520 °C. Raman scattering showed the chemical abruptness of the interfaces at low growth temperatures and indicated a change in the growth mode near 450 °C.

Morphology and frictional properties of scales of Pseudopus apodus (Anguidae, Reptilia).

PubMed

Spinner, Marlene; Bleckmann, Horst; Westhoff, Guido

2015-06-01

In the lizard family Anguidae different levels of limb reduction exist up to a completely limbless body. The locomotion patterns of limbless anguid lizards are similar to the undulating and concertina movements of snakes. Additionally, anguid lizards frequently use a third mode of locomotion, called slide-pushing. During slide-pushing the undulating moving body slides on the ground, while the posterior part of the body is pressed against the substrate. Whereas the macroscopic and microscopic adaptations of snake scales to limbless locomotion are well described, the micromorphology of anguid lizard scales has never been examined. Therefore we studied the macro- and micromorphology of the scales of Pseudopus apodus, an anguid lizard with a snakelike body. In addition, we measured the frictional properties of Pseudopus scales. Our data show that the microstructures of the ventral scales of this anguid lizard are less developed than in snakes. We found, however, a rostro-caudal gradient in macroscopic structuring. Whereas the ventral side of the anterior body was nearly unstructured, the tail had macroscopic longitudinal ridges. Our frictional measurements on rough substrates revealed that the ridges provide a frictional anisotropy: friction was higher in the lateral than in the rostral direction. The observed frictional properties are advantageous for a tail-based slide-pushing locomotion, for which a tail with a high lateral friction is most effective in generating propulsion. Copyright © 2015 Elsevier GmbH. All rights reserved.

X -band rf driven free electron laser driver with optics linearization

DOE PAGES

Sun, Yipeng; Emma, Paul; Raubenheimer, Tor; ...

2014-11-13

In this paper, a compact hard X-ray free electron lasers (FEL) design is proposed with all X-band rf acceleration and two stage bunch compression. It eliminates the need of a harmonic rf linearization section by employing optics linearization in its first stage bunch compression. Quadrupoles and sextupoles are employed in a bunch compressor one (BC1) design, in such a way that second order longitudinal dispersion of BC1 cancels the second order energy correlation in the electron beam. Start-to-end 6-D simulations are performed with all the collective effects included. Emittance growth in the horizontal plane due to coherent synchrotron radiation ismore » investigated and minimized, to be on a similar level with the successfully operating Linac coherent light source (LCLS). At a FEL radiation wavelength of 0.15 nm, a saturation length of 40 meters can be achieved by employing an undulator with a period of 1.5 cm. Without tapering, a FEL radiation power above 10 GW is achieved with a photon pulse length of 50 fs, which is LCLS-like performance. The overall length of the accelerator plus undulator is around 250 meters which is much shorter than the LCLS length of 1230 meters. That makes it possible to build hard X-ray FEL in a laboratory with limited size.« less

Laser-powered dielectric-structures for the production of high-brightness electron and x-ray beams

NASA Astrophysics Data System (ADS)

Travish, Gil; Yoder, Rodney B.

2011-05-01

Laser powered accelerators have been under intensive study for the past decade due to their promise of high gradients and leveraging of rapid technological progress in photonics. Of the various acceleration schemes under examination, those based on dielectric structures may enable the production of relativistic electron beams in breadbox sized systems. When combined with undulators having optical-wavelength periods, these systems could produce high brilliance x-rays which find application in, for instance, medical and industrial imaging. These beams also may open the way for table-top atto-second sciences. Development and testing of these dielectric structures faces a number of challenges including complex beam dynamics, new demands on lasers and optical coupling, beam injection schemes, and fabrication. We describe one approach being pursued at UCLA-the Micro Accelerator Platform (MAP). A structure similar to the MAP has also been designed which produces periodic deflections and acts as an undulator for radiation production, and the prospects for this device will be considered. The lessons learned from the multi-year effort to realize these devices will be presented. Challenges remain with acceleration of sub-relativistic beams, focusing, beam phase stability and extension of these devices to higher beam energies. Our progress in addressing these hurdles will be summarized. Finally, the demands on laser technology and optical coupling will be detailed.

Effects of traveling waves on flow separation and turbulence

NASA Astrophysics Data System (ADS)

Akbarzadeh, Amir Mahdi; Borazjani, Iman; scientific computing; biofluids laboratory Team

2017-11-01

Stable leading edge vortex (LEV) is observed in many flying, hovering and also some aquatic creatures. However, the LEV stability in aquatic animal, in contrast to hovering ones, is not well understood. Here, we study the flow over an inclined plate with an undulatory motion inspired from aquatic swimmers using our immersed boundary, large-eddy simulations (LES). The angle of attack is five degrees and Reynolds number (Re) is 20,000. The undulation is a traveling wave, which has a constant amplitude of 0.01 with respect to chord length and a different wavelength and Strouhal number (St =fA/U, f: frequency, A: amplitude, and U: free stream velocity) for each case. Over a fixed plate the LEV becomes unstable as it reaches the trailing edge and sheds to the wake, whereas over the undulating plate with St =0.2 the LEV becomes stable. The visualization of time average results shows there is a favorable pressure gradient along the tangential direction in cases the LEV becomes stable, which we explain analytically by showing the correlation between the average pressure gradient, St, and wavelength. Finally, the effects of undulatory moving walls of a channel flow on the turbulent statistics is shown. This work was partly supported by the National Science Foundation (NSF) CAREER Grant CBET 1453982, and the Center of Computational Research (CCR) of University at Buffalo.

R&D for a Soft X-Ray Free Electron Laser Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corlett, John; Attwood, David; Byrd, John

2009-06-08

Several recent reports have identified the scientific requirements for a future soft x-ray light source, and a high-repetition-rate free-electron laser (FEL) facility that is responsive to these requirements is now on the horizon. R&D in some critical areas is needed, however, to demonstrate technical performance, thus reducing technical risks and construction costs. Such a facility most likely will be based on a CW superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun operating in CW mode, and on an array of FELs to which the accelerated beam is distributed, each operating at high repetition rate andmore » with even pulse spacing. Dependent on experimental requirements, the individual FELs can be configured for either self-amplified spontaneous emission (SASE), seeded, or oscillator mode of operation, including the use of high-gain harmonic generation (HGHG), echo-enhanced harmonic generation (EEHG), harmonic cascade, or other configurations. In this White Paper we identify the overall accelerator R&D needs, and highlight the most important pre-construction R&D tasks required to value-engineer the design configuration and deliverables for such a facility. In Section 1.4 we identify the comprehensive R&D ultimately needed. We identify below the highest-priority requirements for understanding machine performance and reduce risk and costs at this pre-conceptual design stage. Details of implementing the required tasks will be the subject of future evaluation. Our highest-priority R&D program is the injector, which must be capable of delivering a beam with bunches up to a nanocoulomb at MHz repetition rate and with normalized emittance {le} 1 mm {center_dot} mrad. This will require integrated accelerating structure, cathode, and laser systems development. Cathode materials will impact the choice of laser technology in wavelength and energy per pulse, as well as vacuum requirements in the accelerating structure. Demonstration experiments in advanced seeding techniques, such as EEHG, and other optical manipulations to enhance the FEL process are required to reduce technical risk in producing temporally coherent and ultrashort x-ray output using optical seed lasers. Success of EEHG in particular would result in reduced development and cost of laser systems and accelerator hardware for seeded FELs. With a 1.5-2.5 GeV linac, FELs could operate in the VUV-soft x-ray range, where the actual beam energy will be determined by undulator technology; for example, to use the lower energy would require the use of advanced designs for which undulator R&D is needed. Significant reductions in both unit costs and accelerator costs resulting from the lower electron beam energy required to achieve lasing at a particular wavelength could be obtained with undulator development. Characterization of the wakefields of the vacuum chambers in narrow-gap undulators will be needed to minimize risk in ability to deliver close to transform limited pulses. CW superconducting RF technology for an FEL facility with short bunches at MHz rate and up to mA average current will require selection of design choices in cavity frequency and geometry, higher order mode suppression and power dissipation, RF power supply and distribution, accelerating gradient, and cryogenics systems. R&D is needed to define a cost and performance optimum. Developments in laser technology are proceeding at rapid pace, and progress in high-power lasers, harmonic generation, and tunable sources will need to be tracked.« less

Melorheostosis involving the cervical and upper thoracic spine: radiographic, CT, and MR imaging findings.

PubMed

Motimaya, A M; Meyers, S P

2006-01-01

Melorheostosis, an uncommon mesenchymal dysplasia, rarely affects the axial skeleton. We describe the imaging findings of melorheostosis involving the cervical and upper thoracic spine. Radiographs and CT showed unilateral well-marginated undulating zones of cortical hyperostosis involving multiple vertebrae that were contiguous with a coalescent ossified right paravertebral mass. MR imaging showed zones of signal intensity void on all pulse sequences without contrast enhancement. Conservative management was elected because of lack of interval clinical and imaging changes for 8 years.

Long range coherence in free electron lasers

NASA Technical Reports Server (NTRS)

Colson, W. B.

1984-01-01

The simple free electron laser (FEL) design uses a static, periodic, transverse magnetic field to undulate relativistic electrons traveling along its axis. This allows coupling to a co-propagating optical wave and results in bunching to produce coherent radiation. The advantages of the FEL are continuous tunability, operation at wavelengths ranging from centimeters to angstroms, and high efficiency resulting from the fact that the interaction region only contains light, relativistic electrons, and a magnetic field. Theoretical concepts and operational principles are discussed.

Characterization of an 800 nm SASE FEL at Saturation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nuhn, Heinz-Dieter

2002-11-13

VISA (Visible to Infrared SASE Amplifier) is an FEL (Free Electron Laser) designed to saturate at a radiation wavelength of 800 nm within a 4-m long, strong focusing undulator. Large gain is achieved by driving the FEL with the 72 MeV, high brightness beam of BNL's Accelerator Test Facility (ATF). We present measurements that demonstrate saturation in addition to the frequency spectrum of the FEL radiation. Energy, gain length and spectral characteristics are compared and shown to agree with simulation and theoretical predictions.

Water resources of the Kettle River watershed, east-central Minnesota

USGS Publications Warehouse

Helgesen, John O.; Lindholm, G.F.; Broussard, W.L.; Ericson, D.W.

1973-01-01

The glacial deposits are generally less than 100 feet thick. Bedrock consists of several types and occasionally crops out at land surface. Topography ranges from gently rolling to steeply undulating. About 1,060 square miles is drained by the Kettle River and its tributaries, and about 510 square miles by smaller streams that are direct tributaries to the St. Croix River. Peat and swamp areas are common, particularly in the eastern part of the area. Most of the watershed is forested, mainly with hardwoods.

[Thromboangiitis obliterans (Buerger's disease): update 2015].

PubMed

Klein-Weigel, Peter; Volz, Theresa Sophie; Richter, Jutta

2015-10-01

Thromboangiitis obliterans (Buerger's disease) is a vasculitis with undulating clinical course multisegmentarily affecting small and medium-sized arteries and veins. The disease is closely linked to tobacco-use. Increasing knowledge of autoimmunologic mechanisms in the complex pathophyiology of the disease let to the formulation of an autoimmunity-hypothesis now serving as a new paradigma. New treatment options comprise progenitor-cell-therapy, immunoadsorption, use of sendothelin-receptor-blocking agent Bosentan, and prescriptions of antiphosphodiesterase-V-inhibitors. © Georg Thieme Verlag KG Stuttgart · New York.

Studies on the nematode; Moaciria icosiensis (Seurat, 1917) from Chalcides ocellatus (Forsk.) in Egypt.

PubMed

al-Deen, A; al-Shareef, M F

1996-12-01

With the aid of scanning electron microscopy certain morphological features (e.g.lateral alae, posterior end of male and cuticular surface) are used as principal pilars in the description of the nematode Moaciria icosiensis (Seurat, 1917) from Chalcides ocellatus (Forsk). Cuticular surface is distinguished by minute striations. Lateral alae are smooth and showing undulation. The posterior end of the male is curved and carries specific papillae. These morphological features are specific and aid in proper identification of Moaciria icosiensis.

Thermostatted molecular dynamics: How to avoid the Toda demon hidden in Nose-Hoover dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holian, B.L.; Voter, A.F.; Ravelo, R.

The Nose-Hoover thermostat, which is often used in the hope of modifying molecular dynamics trajectories in order to achieve canonical-ensemble averages, has hidden in it a Toda ``demon,`` which can give rise to unwanted, noncanonical undulations in the instantaneous kinetic temperature. We show how these long-lived oscillations arise from insufficient coupling of the thermostat to the atoms, and give straightforward, practical procedures for avoiding this weak-coupling pathology in isothermal molecular dynamics simulations.

Rapid transitions between defect configurations in a block copolymer melt.

PubMed

Tsarkova, Larisa; Knoll, Armin; Magerle, Robert

2006-07-01

With in situ scanning force microscopy, we image the ordering of cylindrical microdomains in a thin film of a diblock copolymer melt. Tracking the evolution of individual defects reveals elementary steps of defect motion via interfacial undulations and repetitive transitions between distinct defect configurations on a time scale of tens of seconds. The velocity of these transitions suggests a cooperative movement of clusters of chains. The activation energy for the opening/closing of a connection between two cylinders is estimated.

BioCARS: a synchrotron resource for time-resolved X-ray science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graber, T.; Anderson, S.; Brewer, H.

2011-08-16

BioCARS, a NIH-supported national user facility for macromolecular time-resolved X-ray crystallography at the Advanced Photon Source (APS), has recently completed commissioning of an upgraded undulator-based beamline optimized for single-shot laser-pump X-ray-probe measurements with time resolution as short as 100 ps. The source consists of two in-line undulators with periods of 23 and 27 mm that together provide high-flux pink-beam capability at 12 keV as well as first-harmonic coverage from 6.8 to 19 keV. A high-heat-load chopper reduces the average power load on downstream components, thereby preserving the surface figure of a Kirkpatrick-Baez mirror system capable of focusing the X-ray beammore » to a spot size of 90 {micro}m horizontal by 20 {micro}m vertical. A high-speed chopper isolates single X-ray pulses at 1 kHz in both hybrid and 24-bunch modes of the APS storage ring. In hybrid mode each isolated X-ray pulse delivers up to {approx}4 x 10{sup 10} photons to the sample, thereby achieving a time-averaged flux approaching that of fourth-generation X-FEL sources. A new high-power picosecond laser system delivers pulses tunable over the wavelength range 450-2000 nm. These pulses are synchronized to the storage-ring RF clock with long-term stability better than 10 ps RMS. Monochromatic experimental capability with Biosafety Level 3 certification has been retained.« less

Periodization Strategies in Older Adults: Impact on Physical Function and Health.

PubMed

Conlon, Jenny A; Newton, Robert U; Tufano, James J; Banyard, Harry G; Hopper, Amanda J; Ridge, Ashley J; Haff, G Gregory

2016-12-01

This study compared the effect of periodized versus nonperiodized (NP) resistance training (RT) on physical function and health outcomes in older adults. Forty-one apparently healthy untrained older adults (women = 21, men = 20; 70.9 ± 5.1 yr; 166.3 ± 8.2 cm; 72.9 ± 13.4 kg) were recruited and randomly stratified to a NP, block periodized, or daily undulating periodized training group. Outcome measures were assessed at baseline and after a 22-wk × 3 d·wk RT intervention, including; anthropometrics, body composition, blood pressure and biomarkers, maximal strength, functional capacity, balance confidence, and quality of life. Thirty-three subjects satisfied all study requirements and were included in analyses (women = 17, men = 16; 71.3 ± 5.4 yr; 166.3 ± 8.5 cm; 72.5 ± 13.7 kg). The main finding was that all three RT models produced significant improvements in several physical function and physiological health outcomes, including; systolic blood pressure, blood biomarkers, body composition, maximal strength, functional capacity and balance confidence, with no between-group differences. Periodized RT, specifically block periodization and daily undulating periodized, and NP RT are equally effective for promoting significant improvements in physical function and health outcomes among apparently healthy untrained older adults. Therefore, periodization strategies do not appear to be necessary during the initial stages of RT in this population. Practitioners should work toward increasing RT participation in the age via feasible and efficacious interventions targeting long-term adherence in minimally supervised settings.