Alaska Geoid Heights (GEOID96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' x 4' geoid height grid for Alaska is distributed as a GEOID96 model. The computation used 1.1 million terrestrial and marine gravity data held in the...

Using GPS and leveling data in local precise geoid determination and case study

Science.gov (United States)

Erol, B.; Çelik, R. N.; Erol, S.

2003-04-01

the fundamental mathematical equation; N=h-H. In the equation, "h" is the ellipsoidal height of a point P, "H" is the orthometric height of the same point and "N" is "geoid undulation" value. Normally, "H" orthometric height derived from leveling measurements but these measurements are tiring applications. So, while having a geoid model in the region as the essential part of geodetic infrastructure, number leveling measurements can be reduced from the procedure and by this way time and labor is saved. Geoid determination is modeling of the data in such a way that geoid height can be obtained digital or analog at a point whose horizontal position is known. Geoid models can be developed for local, regional or global regions. Using satellite techniques, especially GPS, in geodetic measurements are increased importance of geoid. Because geoid is a natural tie between high precision geodetic coordinates and coordinates which obtained from satellites. There are several geoid determination methods according to used data and models. GPS/Leveling method, which is also known as geometric method, is one of these methods. This method is appropriate for local precise geoid determination in respectively small areas. In this paper, it is going to be given information about GPS/Leveling geoid determination method and mathematical models, which are used in geoid determination with this method. And Izmir local geoid model will be presented as a case study. Izmir is one of the west metropolitan cities of Turkey and located near Aegean Sea. The topography is extremely rough in the region. There are two different geoid determination studies which were carried out in 1996 and 2001 in Izmir. Both models were accomplished according to GPS/Leveling method. Those two geoid models of Izmir Metropolitan region are investigated in here, the conflict of them were discussed. The relation between distribution of common reference points and differences of geoid undulation values, which are calculated

U.S. Geoid Heights (GEOID96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the conterminous United States is the GEOID96 model. The computation used about 1.8 million terrestrial and marine gravity data held in...

PR/VI Geoid Heights (GEOID96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for Puerto Rico and the Virgin Islands is distributed as a GEOID96 model. The computation used 26,000 terrestrial and marine gravity data...

Research on transition undulator radiation

International Nuclear Information System (INIS)

Lu Shuzhuang; Dai Zhimin; Zhao Xiaofeng

2000-01-01

The theory of transition undulator radiation was described first, then the properties of infrared and far-infrared transition undulator radiation of SSRF U9.0 were explored by the methods of analytical treatment and numerical simulation, and the influence of beam energy spread, emittance, and magnetic field errors on transition undulator radiation was given also. It was shown that the flux density of the infrared and far-infrared transition undulator radiation of the SSRF U9.0 was high (e.g., the maximum flux density might reach 35 x 10 13 photons/(s·mrad 2 ·BW), collecting angle φ = 0.23 mrad, and the effects of beam energy spread, emittance and magnetic field errors on the radiation flux density were small

Induction shimming: A new shimming concept for superconductive undulators

Directory of Open Access Journals (Sweden)

D. Wollmann

2008-10-01

Full Text Available Undulators are the most advanced sources for the generation of synchrotron radiation. The photons generated by a single electron add up coherently along the electron trajectory. In order to do so, the oscillatory motion of the electron has to be in phase with the emitted photons along the whole undulator. Small magnetic errors can cause unwanted destructive interferences. In standard permanent magnet undulators, the magnetic errors are reduced by applying shimming techniques. Superconductive undulators have higher magnetic fields than permanent magnet undulators but shimming is more complex. In this paper it is shown that coupled superconductive loops installed along the surface of the superconductive undulator coil can significantly reduce the destructive effect of the field errors. This new idea might allow the building of undulators with a superior field quality.

Alaska/Yukon Geoid Improvement by a Data-Driven Stokes's Kernel Modification Approach

Science.gov (United States)

Li, Xiaopeng; Roman, Daniel R.

2015-04-01

Geoid modeling over Alaska of USA and Yukon Canada being a trans-national issue faces a great challenge primarily due to the inhomogeneous surface gravity data (Saleh et al, 2013) and the dynamic geology (Freymueller et al, 2008) as well as its complex geological rheology. Previous study (Roman and Li 2014) used updated satellite models (Bruinsma et al 2013) and newly acquired aerogravity data from the GRAV-D project (Smith 2007) to capture the gravity field changes in the targeting areas primarily in the middle-to-long wavelength. In CONUS, the geoid model was largely improved. However, the precision of the resulted geoid model in Alaska was still in the decimeter level, 19cm at the 32 tide bench marks and 24cm on the 202 GPS/Leveling bench marks that gives a total of 23.8cm at all of these calibrated surface control points, where the datum bias was removed. Conventional kernel modification methods in this area (Li and Wang 2011) had limited effects on improving the precision of the geoid models. To compensate the geoid miss fits, a new Stokes's kernel modification method based on a data-driven technique is presented in this study. First, the method was tested on simulated data sets (Fig. 1), where the geoid errors have been reduced by 2 orders of magnitude (Fig 2). For the real data sets, some iteration steps are required to overcome the rank deficiency problem caused by the limited control data that are irregularly distributed in the target area. For instance, after 3 iterations, the standard deviation dropped about 2.7cm (Fig 3). Modification at other critical degrees can further minimize the geoid model miss fits caused either by the gravity error or the remaining datum error in the control points.

Principal Hawaiian Islands Geoid Heights (GEOID96)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the Principal Hawaiian Islands is distributed as a GEOID96 model. The computation used 61,000 terrestrial and marine gravity data held...

Research of a hybrid undulator

International Nuclear Information System (INIS)

Ma Youwu; Wu Bing; Liu Bo

1995-12-01

A 1.5 m tapered hybrid undulator has been designed and built for mid-infrared free electron laser experiments at CIAE. The undulator utilizes the REC-steel hybrid configuration. The magnetic gap and magnetic field taper can be continuously adjusted. The rms error of the peak field is less than 0.53%. The electron trajectory deviation is around 0.03 mm. The design of undulator, sorting of magnets in hybrid undulator using simulated annealing technique, the motion of electron beam in the ideal and measured magnetic field, magnetic field measurement technique and magnetic field adjustment are described. (6 refs., 10 figs., 1 tab)

Inductive Shimming of Superconductive Undulators - Preparations for a realistic test

CERN Document Server

Schoerling, D; Bernhard,; Burkart, F; Ehlers, S; Gerstl, S; Grau, A; Peiffer, P; Rossmanith, R; Wollmann, D

2010-01-01

The monochromaticity and intensity of synchrotron light emitted by undulators strongly depend on the undulator field quality. For the particular case of superconductive undulators it was shown recently that their field quality can be significantly improved by an array of coupled high temperature superconductor loops attached to the surface of the superconductive undulator. Local field errors induce currents in the coupled closed superconducting loops and, as a result, the hereby generated magnetic field minimizes the field errors. In previous papers the concept was described theoretically and a proof-of-principle experiment was reported. This paper reports on a prepatation experiment for the first quantitative measurement of the phase error reduction in a 13-period short model undulator equipped with a full-scale induction shimming system.

Resorting the NIST undulator using simulated annealing for field error reduction

International Nuclear Information System (INIS)

Denbeaux, Greg; Johnson, Lewis E.; Madey, John M.J.

2000-01-01

We have used a simulated annealing algorithm to sort the samarium cobalt blocks and vanadium permendur poles in the hybrid NIST undulator to optimize the spectrum of the emitted light. While simulated annealing has proven highly effective in sorting of the SmCo blocks in pure REC undulators, the reliance on magnetically 'soft' poles operating near saturation to concentrate the flux in hybrid undulators introduces a pair of additional variables - the permeability and saturation induction of the poles - which limit the utility of the assumption of superposition on which most simulated annealing codes rely. Detailed magnetic measurements clearly demonstrated the failure of the superposition principle due to random variations in the permeability in the 'unsorted' NIST undulator. To deal with the issue, we measured both the magnetization of the REC blocks and the permeability of the NIST's integrated vanadium permendur poles, and implemented a sorting criteria which minimized the pole-to-pole variations in permeability to satisfy the criteria for realization of superposition on a nearest-neighbor basis. Though still imperfect, the computed spectrum of the radiation from the re-sorted and annealed NIST undulator is significantly superior to that of the original, unsorted device

Measurement, sorting and tuning of LCLS undulator magnets

CERN Document Server

Vasserman, I B; Dejus, Roger J; Moog, E; Trakhtenberg, E; Vinokurov, N A

2002-01-01

Currently, a Linac Coherent Light Source (LCLS) prototype undulator is under construction. The prototype is a 3.4-m-long hybrid-type undulator with fixed gap of 6 mm. The period length is 30 mm and the number of poles is 226. For this undulator, 450 NdFeB magnet blocks are used. This project does not have demanding requirements for multipole component errors, but the field strength at x=0 should be as precise as possible to provide proper particle steering and phase errors. The first set of magnetic blocks has been measured. The strength and direction of magnetization of the magnet blocks are measured using a Helmholtz coil system. In addition to this, Hall probe measurements are performed for magnet blocks while they are mounted in a specially designed cassette with vanadium-permendur poles. The magnet blocks will be sorted using these data to minimize errors. Computer simulations show that magnets may be sorted in decreasing strengths with little or no additional tuning of the undulators.

The influence of the atmosphere on geoid and potential coefficient determinations from gravity data

Science.gov (United States)

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.

Optimization of permanent-magnet undulator magnets ordering using simulated annealing algorithm

International Nuclear Information System (INIS)

Chen Nian; He Duohui; Li Ge; Jia Qika; Zhang Pengfei; Xu Hongliang; Cai Genwang

2005-01-01

Pure permanent-magnet undulator consists of many magnets. The unavoidable remanence divergence of these magnets causes the undulator magnetic field error, which will affect the functional mode of the storage ring and the quality of the spontaneous emission spectrum. Optimizing permanent-magnet undulator magnets ordering using simulated annealing algorithm before installing undulator magnets, the first field integral can be reduced to 10 -6 T·m, the second integral to 10 -6 T·m 2 and the peak field error to less than 10 -4 . The optimized results are independent of the initial solution. This paper gives the optimizing process in detail and puts forward a method to quickly calculate the peak field error and field integral according to the magnet remanence. (authors)

Oceanic geoid and tides derived from GEOS 3 satellite data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1979-01-01

Two sets of GEOS 3 altimeter data which fall within about a 2.5-deg width are analyzed for ocean geoid and tides. One set covers a path from Newfoundland to Cuba, and the other a path from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M2, O1, S2, and K1, are derived along the two strips. While the analyses produced convergent solutions for all 40 cases, the uncertainty caused by the linear orbital bias error of the satellite is too large to claim that the solutions represent the true ocean tides in the area. A spot check of the result with the Mode deep-sea tide gauge data shows poor agreement. A positive conclusion of this study is that despite the uncertain orbital error the oceanic geoid obtained through this analysis can improve significantly the short-wavelength structure over existing spherical harmonic geoid models.

Undulator commissioning by characterization of radiation in x-ray free electron lasers

Directory of Open Access Journals (Sweden)

Takashi Tanaka

2012-11-01

Full Text Available In x-ray free electron lasers (XFELs where a long undulator composed of many segments is installed, there exist a number of error sources to reduce the FEL gain such as the trajectory error, K value discrepancy, and phase mismatch, which are related to the segmented-undulator structure. Undulator commissioning, which refers to the tuning and alignment processes to eliminate the possible error sources, is thus an important step toward realization of lasing. In the SPring-8 angstrom compact free electron laser (SACLA facility, the undulator commissioning has been carried out by means of characterization of x-ray radiation, i.e., measurements of the spatial and spectral profiles of monochromatized spontaneous undulator radiation as well as by probing the FEL intensity. The achieved tuning and alignment accuracies estimated from the statistics of actual measurements in SACLA show the effectiveness of this commissioning scheme.

Permanent-magnet helical undulator for a millimeter-wave free electron laser

International Nuclear Information System (INIS)

Lee, Jongmin; Jeong, Young-Uk; Lee, Byung-Cheol; Kim, Sun-Kook; Cho, Sung-Oh

1995-01-01

Permanent-magnet helical undulator for a millimeter-wave free-electron laser was designed and constructed. The configuration of the undulator is based on bifilar-type permanent-magnet helical undulator and Halbach-type planar undulator. This new configuration shows enhanced magnetic field and low field error. Period, total length and peak magnetic-field amplitude of the undulator is 36 mm, 900 mm and 1.44 kG, respectively. Adiabatic tapering of the magnetic field in end sides of the undulator was achieved using stepped soft-iron tubes. (author)

Magnetic Measurement System for the NSLS Superconducting Undulator Vertical Test Facility

CERN Document Server

Harder, David; Skaritka, John

2005-01-01

One of the challenges of small-gap superconducting undulators is measurement of magnetic fields within the cold bore to characterize the device performance and to determine magnetic field errors for correction or shimming, as is done for room-temperature undulators. Both detailed field maps and integrated field measurements are required. This paper describes a 6-element, cryogenic Hall probe field mapper for the NSLS Superconducting Undulator Vertical Test Facility (VTF). The probe is designed to work in an aperture only 3 mm high. A pulsed-wire insert is also being developed, for visualization of the trajectory, for locating steering errors and for determining integrated multi-pole errors. The pulsed-wire insert will be interchangeable with the Hall probe mapper. The VTF and the magnetic measurement systems can accommodate undulators up to 0.4 m in length.

Challenges of in-vacuum and cryogenic permanent magnet undulator technologies

Directory of Open Access Journals (Sweden)

Jui-Che Huang

2017-06-01

Full Text Available An in-vacuum undulator (IVU provides a means to reach high-brilliance x rays in medium energy storage rings. The development of short period undulators with low phase errors creates the opportunity for an unprecedented brilliant light source in a storage ring. Since the spectral quality from cryogenic permanent magnet undulators (CPMUs has surpassed that of IVUs, NdFeB or PrFeB CPMUs have been proposed for many new advanced storage rings to reach high brilliance x-ray photon beams. In a low emittance ring, not only the performance of the undulator but also the choice of the lattice functions are important design considerations. Optimum betatron functions and a zero-dispersion function shall be provided in the straight sections for IVU/CPMUs. In this paper, relevant factors and design issues for IVUs and CPMUs are discussed together with many technological challenges in short period undulators associated with beam induced–heat load, phase errors, and the deformation of support girders.

Challenges of in-vacuum and cryogenic permanent magnet undulator technologies

Science.gov (United States)

Huang, Jui-Che; Kitamura, Hideo; Yang, Chin-Kang; Chang, Cheng-Hsing; Chang, Cheng-Hsiang; Hwang, Ching-Shiang

2017-06-01

An in-vacuum undulator (IVU) provides a means to reach high-brilliance x rays in medium energy storage rings. The development of short period undulators with low phase errors creates the opportunity for an unprecedented brilliant light source in a storage ring. Since the spectral quality from cryogenic permanent magnet undulators (CPMUs) has surpassed that of IVUs, NdFeB or PrFeB CPMUs have been proposed for many new advanced storage rings to reach high brilliance x-ray photon beams. In a low emittance ring, not only the performance of the undulator but also the choice of the lattice functions are important design considerations. Optimum betatron functions and a zero-dispersion function shall be provided in the straight sections for IVU/CPMUs. In this paper, relevant factors and design issues for IVUs and CPMUs are discussed together with many technological challenges in short period undulators associated with beam induced-heat load, phase errors, and the deformation of support girders.

THE VISA FEL UNDULATOR

International Nuclear Information System (INIS)

CARR, R.; CORNACCHIA, M.; EMMA, P.; NUHN, H.D.; FULAND, R.; JOHNSON, E.; RAKOWSKY, G.; LIDIA, S.; BERTOLINI, L.; LIBKIND, M.; FRIGOLA, P.; PELLEGRINI, C.; ROSENZWEIG, J.

1998-01-01

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 undulator 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

Tuning and characterization of the {open_quotes}Teufel{close_quotes}-undulator

Energy Technology Data Exchange (ETDEWEB)

Verschuur, J.W.J.; Ernst, G.J.; Witteman, W.J. [Univ. of Twente, Enschede (Netherlands)

1995-12-31

Three important criteria are used to tune the undulator are: reduce longitudinal phase errors, have approximately equal two plane focusing and have a good overlap between the electron beam and the optical beam. Although these criteria are the main design goals it is hard to meet them directly from the assembling. Small errors inevitably appear during the assembly, even when care is taken to keep the tolerances as tight as possible. The magnetic field was constantly monitored during construction using the pulsed wire method. However some kind of tuning mechanism is always needed to improve the performance of the undulator. The undulator we designed and build is of the Hybrid type, i.e. permanent magnets and high permeable poles. The well known method of using small permanent magnets to correct the field errors is nearly impossible due to the presence of iron poles. Hence, as a logical step, we decided to try to correct the various errors with shims in the form of small iron plates. The shims were put on the pole face at the edge of the poles. Different configurations were used to correct the different kind of errors. In the presentation an overview of the various shim configurations will be discussed. Steering errors are quite easy to correct, since only dipole fields are involved. We did put quite some effort in correcting the quadrupole errors. Gradients dBy/dx and dBx/dy were easy to correct with two shims on one side. The other gradients, on the other hand needed extensive shimming to be corrected. The error correction is limited by the presence of sextupole errors. We even found by experience that sextupole errors increased with the number of shims used. The ratio of the focusing strength of the undulator is measured to be 3/2, being slightly stronger in the direction of the wiggle motion. Longitudinal phase errors are introduced by amplitude and wavelength deviations in the undulator.

Investigating the Indian Ocean Geoid Low

Science.gov (United States)

Ghosh, A.; Gollapalli, T.; Steinberger, B. M.

2016-12-01

The lowest geoid anomaly on Earth lies in the Indian Ocean just south of the Indian peninsula.Several theories have been proposed to explain this geoid low, most of which invoke past subduction. Some recent studies have alsoargued that high velocity anomalies in the lower mantle coupled with low velocity anomalies in the upper mantle are responsible for these negative geoidanomalies. However, there is no general consensus regarding the source of the Indian Ocean negative geoid. We investigate the source of this geoid low by using forward models of density driven mantle convection using CitcomS. We test various tomography models in our flow calculations with different radial and lateral viscosity variations. Many tomography modelsproduce a fairly high correlation to the global geoid, however none could match the precise location of the geoid low in the Indian Ocean. Amerged P-wave model of LLNL-G3DV3 in the Indian Ocean region and S40rts elsewhere yields a good fit to the geoid anomaly, both in pattern and magnitude.The source of this geoid low seems to stem from a low velocity anomaly stretching from a depth of 300 km up to 700 km in the northern Indian Ocean region.This velocity anomaly could potentially arise from material rising along the edge of the African LLSVP and moving towards the northeast, facilitated by the movementof the Indian plate in the same direction.

A simple model based magnet sorting algorithm for planar hybrid undulators

International Nuclear Information System (INIS)

Rakowsky, G.

2010-01-01

Various magnet sorting strategies have been used to optimize undulator performance, ranging from intuitive pairing of high- and low-strength magnets, to full 3D FEM simulation with 3-axis Helmholtz coil magnet data. In the extreme, swapping magnets in a full field model to minimize trajectory wander and rms phase error can be time consuming. This paper presents a simpler approach, extending the field error signature concept to obtain trajectory displacement, kick angle and phase error signatures for each component of magnetization error from a Radia model of a short hybrid-PM undulator. We demonstrate that steering errors and phase errors are essentially decoupled and scalable from measured X, Y and Z components of magnetization. Then, for any given sequence of magnets, rms trajectory and phase errors are obtained from simple cumulative sums of the scaled displacements and phase errors. The cost function (a weighted sum of these errors) is then minimized by swapping magnets, using one's favorite optimization algorithm. This approach was applied recently at NSLS to a short in-vacuum undulator, which required no subsequent trajectory or phase shimming. Trajectory and phase signatures are also obtained for some mechanical errors, to guide 'virtual shimming' and specifying mechanical tolerances. Some simple inhomogeneities are modeled to assess their error contributions.

Mexico Geoid Heights (MEXICO97)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for Mexico, and North-Central America, is the MEXICO97 geoid model. The computation used about one million terrestrial and marine gravity...

Estimating Gravity Biases with Wavelets in Support of a 1-cm Accurate Geoid Model

Science.gov (United States)

Ahlgren, K.; Li, X.

2017-12-01

Systematic errors that reside in surface gravity datasets are one of the major hurdles in constructing a high-accuracy geoid model at high resolutions. The National Oceanic and Atmospheric Administration's (NOAA) National Geodetic Survey (NGS) has an extensive historical surface gravity dataset consisting of approximately 10 million gravity points that are known to have systematic biases at the mGal level (Saleh et al. 2013). As most relevant metadata is absent, estimating and removing these errors to be consistent with a global geopotential model and airborne data in the corresponding wavelength is quite a difficult endeavor. However, this is crucial to support a 1-cm accurate geoid model for the United States. With recently available independent gravity information from GRACE/GOCE and airborne gravity from the NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project, several different methods of bias estimation are investigated which utilize radial basis functions and wavelet decomposition. We estimate a surface gravity value by incorporating a satellite gravity model, airborne gravity data, and forward-modeled topography at wavelet levels according to each dataset's spatial wavelength. Considering the estimated gravity values over an entire gravity survey, an estimate of the bias and/or correction for the entire survey can be found and applied. In order to assess the accuracy of each bias estimation method, two techniques are used. First, each bias estimation method is used to predict the bias for two high-quality (unbiased and high accuracy) geoid slope validation surveys (GSVS) (Smith et al. 2013 & Wang et al. 2017). Since these surveys are unbiased, the various bias estimation methods should reflect that and provide an absolute accuracy metric for each of the bias estimation methods. Secondly, the corrected gravity datasets from each of the bias estimation methods are used to build a geoid model. The accuracy of each geoid model

Final construction of the C.R.E.O.L. 8 millimeter period hybrid undulator

Energy Technology Data Exchange (ETDEWEB)

Tesch, P.; Gallagher, J.; Elias, L. [Center for Research and Education in Optics and Lasers, Orlando, FL (United States)

1995-12-31

The construction of an 8 millimeter period hybrid undulator for the C.R.E.O.L. high power far-infared free electron laser has just been completed. This FEL is expected to come on-line in the fall of 1995 and produce close to a kilowatt of continuous power at wavelengths of 225 - 800 microns. The undulator has extremely precise mechanical tolerances and high field uniformity allowing for high electron beam recovery rates. Almost complete beam recovery is required for DC operation at high currents. A novel method for measuring the magnetic properties of individual magnets and sorting the magnets to reduce magnetic field errors will be reported. The peak field and phase errors of the undulator without the pole pieces are reduced through a magnet ordering procedure. These errors are further reduced by inserting and tuning adjustable pole pieces. The reduction of field errors through these two techniques will be presented. An analysis of the final undulator errors and the results of measurements of the mechanical tolerances will be presented.

Multi-Objective Optimization for Pure Permanent-Magnet Undulator Magnets Ordering Using Modified Simulated Annealing

CERN Document Server

Chen Nian; Li, Ge

2004-01-01

Undulator field errors influence the electron beam trajectories and lower the radiation quality. Angular deflection of electron beam is determined by first field integral, orbital displacement of electron beam is determined by second field integral and radiation quality can be evaluated by rms field error or phase error. Appropriate ordering of magnets can greatly reduce the errors. We apply a modified simulated annealing algorithm to this multi-objective optimization problem, taking first field integral, second field integral and rms field error as objective functions. Undulator with small field errors can be designed by this method within a reasonable calculation time even for the case of hundreds of magnets (first field integral reduced to 10-6T·m, second integral to 10-6T·m2 and rms field error to 0.01%). Thus, the field correction after assembling of undulator will be greatly simplified. This paper gives the optimizing process in detail and puts forward a new method to quickly calculate the rms field e...

First Release of Gravimetric Geoid Model over Saudi Arabia Based on Terrestrial Gravity and GOCE Satellite Data: KSAG01

Science.gov (United States)

Alothman, Abdulaziz; Elsaka, Basem

2016-04-01

A new gravimetric quasi-geoid, known as KSAG0, has been developed recently by Remove-Compute-Restore techniques (RCR), provided by the GRAVSOFT software, using gravimetric free air anomalies. The terrestrial gravity data used in this computations are: 1145 gravity field anomalies observed by ARAMCO (Saudi Arabian Oil Company) and 2470 Gravity measurements from BGI (Bureau Gravimétrique International). The computations were carried out implementing the least squares collocation method through the RCR techniques. The KSAG01 is based on merging in addition to the terrestrial gravity observations, GOCE satellite model (Eigen-6C4) and global gravity model (EGM2008) have been utilized in the computations. The long, medium and short wavelength spectrum of the height anomalies were compensated from Eigen-6C4 and EGM2008 geoid models truncated up to Degree and order (d/o) up to 2190. KSAG01 geoid covers 100 per cent of the kingdom, with geoid heights range from - 37.513 m in the southeast to 23.183 m in the northwest of the country. The accuracy of the geoid is governed by the accuracy, distribution, and spacing of the observations. The standard deviation of the predicted geoid heights is 0.115 m, with maximum errors of about 0.612 m. The RMS of geoid noise ranges from 0.019 m to 0.04 m. Comparison of the predicted gravimetric geoid with EGM, GOCE, and GPS/Levelling geoids, reveals a considerable improvements of the quasi-geoid heights over Saudi Arabia.

Geoid models around Sognefjord using depth data

DEFF Research Database (Denmark)

Dahl, O.C.; Forsberg, René

1998-01-01

the computed gravimetric geoid by as much as a few decimeters. The effect was detectable to a distance of more than 100 km. All calculated geoids, both with and without bathymetry data in the terrain model, fit the geoidal heights determined by available Global Positioning System (GPS) and levelling heights...... at the sub-decimetre level. Contrary to expectations, the accuracy in geoid prediction was reduced when using bathymetric data. The geoid changes were largest over the fjord where no GPS points were located. Different methods on the same area [isostatic and Residual Terrain Model (RTM)-terrain reductions...

Micropole undulators: Novel insertion devices for synchrotron sources

International Nuclear Information System (INIS)

Toor, A.; Csonka, P.; Tatchyn, R.

1989-01-01

Micropole undulators (wigglers) are undulators (wigglers) with submillimeter periods and are referred to, generically, as micropole insertion devices. Compared to ordinary insertion devices, whose period λ u is typically ≥l cm, micropole devices have periods smaller by a factor f≤10. Therefore, the first-harmonic radiation emitted by a micropole undulator will have its photon energy E γ increased by f and its spectral purity Δλ/λ by f, provided the total length of the undulator l u stays unchanged, and magnetic field errors, as well as the electron-beam emittance, are sufficiently small. Furthermore, to generate photons of the same E γ as from the conventional device, the electron-beam energy E e can be reduced by f 1/2 , resulting in significantly lower construction and operating costs. Radiative energy losses can be correspondingly diminished for the associated storage rings. In this paper we report on results recently obtained by us in the practical implementation and design of micropole undulators at the Stanford Synchrotron Radiation Laboratory (SSRL) and the Lawrence Livermore National Laboratory (LLNL). Based on our work, micropole undulators with f≤10 4 appear feasible at the present time

Performance of a superconducting, high field subcentimeter undulator

International Nuclear Information System (INIS)

Ben-Zvi, I.; Fernow, R.; Gallardo, J.; Ingold, G.; Sampson, W.; Woodle, M.

1991-01-01

A Superconducting 8.80mm wavelength undulator is under construction for the 500nm Free-Electron Laser at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory. We present results on the design, construction and performance of this novel undulator structure. A field on axis of 0.51T has been measured for a 4.40mm gap, with a current 20% below the quench current. Our simple design focuses on minimizing the accumulation of errors by minimizing the numbers of parts and by using a ferromagnetic yoke. The magnetic field error is less than 0.30% rms as manufactured (without shimming). The third harmonic content is less than 0.1% of the fundamental

Microwave undulator

International Nuclear Information System (INIS)

Batchelor, K.

1986-03-01

The theory of a microwave undulator utilizing a plane rectangular waveguide operating in the TE/sub 10n/ mode and other higher order modes is presented. Based on this, a possible undulator configuration is analyzed, leading to the conclusion that the microwave undulator represents a viable option for undulator wavelength down to about 1 cm where peak voltage and available microwave power considerations limit effectiveness. 4 refs., 4 figs

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Precise information of geoid undulations is essential for obtaining the orthometric heights from Global Positioning System (GPS) measurements over any region; apart from providing the information of subsurface density distribution. This paper presents computation of geoid undulations over a part of southern Indian region ...

Synchrotron radiation from magnetic undulators as a prospective diagnostic tool

International Nuclear Information System (INIS)

Barbini, R.; Ciocci, F.; Dattoli, G.; Torre, A.; Ginnessi, L.

1989-01-01

The brightness of the radiation emitted by an ultrarelativistic e-beam passing through a magnetic undulator is sensitive to the beam quality (namely, energy spread and emittances) and to the undulator characteristics (i.e., possible random errors both in intensity and direction of magnetization, etc.) The spectrum distortion induced by the above effects and the possibility of using the undulator radiation as a diagnostic tool is discussed. Finally the importance of near-field effects when the radiation is detectedunfocussed off-axis and how they can combine with the effects induced by the beam emittances to produced a larger on-axis inhomogeneous broadening

LCLS undulator production

International Nuclear Information System (INIS)

Trakhtenberg, E.; Barsz, T.; Lawrence, G.; Sasaki, S.; Vasserman, I.; White, M.; Goldfarb, G.; Lagonsky, S.; Sorsher, S.; Becker, T.; Dufresne, S.; Schuermann, R.

2008-01-01

Design and construction of the undulators for the linac coherent light source (LCLS) at the Stanford Linear Accelerator Center (SLAC) is the responsibility of Argonne National Laboratory (ANL). A full-scale prototype undulator was constructed in-house and extensively tested at Argonne's advanced photon source (APS). The device was tunable to well within the LCLS requirements and was stable for five years. Experience constructing the prototype undulator led us to conclude that with appropriate engineering design and detailed assembly procedures, precision undulators can be constructed by highly-qualified industrial vendors without undulator-construction experience. Argonne's detailed technological knowledge and experience were transferred to the successful bidders who produced outstanding undulators. Our production concept for the 3.4-m-long, fixed-gap, planar-hybrid undulators with a 30-mm period is discussed. Manufacturing, quality assurance, and acceptance testing details are also presented.

Refining geoid and vertical gradient of gravity anomaly

Directory of Open Access Journals (Sweden)

Zhang Chijun

2011-11-01

Full Text Available We have derived and tested several relations between geoid (N and quasi-geoid (ζ with model validation. The elevation correction consists of the first-term (Bouguer anomaly and second-term (vertical gradient of gravity anomaly. The vertical gradient was obtained from direct measurement and terrain calculation. The test results demonstrated that the precision of geoid can reach centimeter-level in mountains less than 5000 meters high.

Practical application of the geometric geoid for heighting over ...

African Journals Online (AJOL)

This is because a geoid model is required to convert ellipsoidal heights to orthometric heights that are used in practice. A local geometric geoid ... The geoid height is expressed as a function of the local plane coordinates through a biquadratic surface polynomial, using 14 GPS/levelling points. Five points have been used ...

Undulators at the ALS

International Nuclear Information System (INIS)

Hoyer, E.; Akre, J.; Chin, J.

1994-07-01

At Lawrence Berkeley Laboratory's (LBL) Advanced Light Source (ALS), three 4.6 m long undulators have been completed, tested and installed. A fourth is under construction. The completed undulators include two 5.0 cm period length, 89 period devices (U5.0s) which achieve a 0.85 T effective field at a 14 mm minimum gap and a 8.0 cm period length, 55 period device (U8.0) that reaches a 1.2 T effective field at a 14 mm minimum gap. The undulator under construction is a 10.0 cm period length, 43 period device (U10.0) that is designed to achieve 0.98 T at a 23 mm gap. Undulator magnetic gap variation (rms) is within 25 microns over the periodic structure length. Reproducibility of the adjustable magnetic gap has been measured to be within +/- 5 microns. Gap adjusting range is from 14 mm to 210 mm, which can be scanned in one minute. The 5.1 m long vacuum chambers are flat in the vertical direction to within 0.74 mm and straight in the horizontal direction to within 0.08 mm over the 4.6 m magnetic structure sections. Vacuum chamber base pressures after UHV beam conditioning are. in the mid 10 -11 Torr range and storage ring operating pressures with full current are in the low 10 -10 Torr range. Measurements show that the uncorrelated magnetic field errors are 0.23%, and 0.20% for the two U5.Os and the U8.0 respectively and that the field integrals are small over the 1 cm by 6 cm beam aperture. Device description, fabrication, and measurements are presented

Hybrid undulator numerical optimization

Energy Technology Data Exchange (ETDEWEB)

Hairetdinov, A.H. [Kurchatov Institute, Moscow (Russian Federation); Zukov, A.A. [Solid State Physics Institute, Chernogolovka (Russian Federation)

1995-12-31

3D properties of the hybrid undulator scheme arc studied numerically using PANDIRA code. It is shown that there exist two well defined sets of undulator parameters which provide either maximum on-axis field amplitude or minimal higher harmonics amplitude of the basic undulator field. Thus the alternative between higher field amplitude or pure sinusoidal field exists. The behavior of the undulator field amplitude and harmonics structure for a large set of (undulator gap)/(undulator wavelength) values is demonstrated.

How to handle topography in practical geoid determination: three examples

DEFF Research Database (Denmark)

Omang, O.C.D.; Forsberg, René

2000-01-01

Three different methods of handling topography in geoid determination were investigated. The first two methods employ the residual terrain model (RTM) remove-restore technique, yielding the quasi-geoid, whereas the third method uses the classical Helmert condensation method, yielding the geoid. All...

A detailed gravimetric geoid from North America to Eurasia

Science.gov (United States)

Vincent, S. F.; Strange, W. E.; Marsh, J. G.

1972-01-01

A detailed gravimetric geoid of the United States, North Atlantic, and Eurasia, which was computed from a combination of satellite derived and surface gravity data, is presented. The precision of this detailed geoid is + or - 2 to + or - 3 m in the continents but may be in the range of 5 to 7 m in those areas where data is sparse. Comparisons of the detailed gravimetric geoid with results of Rapp, Fischer, and Rice for the United States, Bomford in Europe, and Heiskanen and Fischer in India are presented. Comparisons are also presented with geoid heights from satellite solutions for geocentric station coordinates in North America, the Caribbean, and Europe.

Inter-comparison of state-of-the-art MSS and geoid models in the Arctic Ocean

DEFF Research Database (Denmark)

Skourup, Henriette; Farrell, Sinead; Hendricks, Stefan

in errors in the estimated freeboard heights, especially in areas with a sparse lead distribution in consolidated ice conditions. Additionally these errors can impact ocean geostrophic current estimates and remaining biases in the models may impact longer-term, multi-sensor oceanographic time-series of sea......State-of-the-art Arctic Ocean mean sea surface (MSS) and geoid models are used to support sea ice freeboard estimation from satellite altimeters, and for oceanographic studies. However, errors in a given model in the high frequency domain, e.g. due to unresolved gravity features, can result...

Airborne geoid mapping of land and sea areas of East Malaysia

Science.gov (United States)

Jamil, H.; Kadir, M.; Forsberg, R.; Olesen, A.; Isa, M. N.; Rasidi, S.; Mohamed, A.; Chihat, Z.; Nielsen, E.; Majid, F.; Talib, K.; Aman, S.

2017-02-01

This paper describes the development of a new geoid-based vertical datum from airborne gravity data, by the Department of Survey and Mapping Malaysia, on land and in the South China Sea out of the coast of East Malaysia region, covering an area of about 610,000 square kilometres. More than 107,000 km flight line of airborne gravity data over land and marine areas of East Malaysia has been combined to provide a seamless land-to-sea gravity field coverage; with an estimated accuracy of better than 2.0 mGal. The iMAR-IMU processed gravity anomaly data has been used during a 2014-2016 airborne survey to extend a composite gravity solution across a number of minor gaps on selected lines, using a draping technique. The geoid computations were all done with the GRAVSOFT suite of programs from DTU-Space. EGM2008 augmented with GOCE spherical harmonic model has been used to spherical harmonic degree N = 720. The gravimetric geoid first was tied at one tide-gauge (in Kota Kinabalu, KK2019) to produce a fitted geoid, my_geoid2017_fit_kk. The fitted geoid was offset from the gravimetric geoid by +0.852 m, based on the comparison at the tide-gauge benchmark KK2019. Consequently, orthometric height at the six other tide gauge stations was computed from HGPS Lev = hGPS - Nmy_geoid2017_.t_kk. Comparison of the conventional (HLev) and GPS-levelling heights (HGPS Lev) at the six tide gauge locations indicate RMS height difference of 2.6 cm. The final gravimetric geoidwas fitted to the seven tide gauge stations and is known as my_geoid2017_fit_east. The accuracy of the gravimetric geoid is estimated to be better than 5 cm across most of East Malaysia land and marine areas

Permanent magnet steerers for canted undulators at the ESRF

Energy Technology Data Exchange (ETDEWEB)

Le Bec, G., E-mail: lebec@esrf.fr [ESRF, 6 r. J. Horowitz, BP 220, 38043 Grenoble Cedex 9 (France); Chavanne, J. [ESRF, 6 r. J. Horowitz, BP 220, 38043 Grenoble Cedex 9 (France)

2012-02-01

A number of canted undulators will be installed at the ESRF. Permanent Magnet Steerers will be used for providing canting angles up to 5.4 mrad. These steerers have been optimized in view of the limited space available and the required field quality. The magnetic interaction between the steerers and the undulators may lead to additional optical phase errors: auxiliary poles have been added to obtain a fast decrease of the fringe field. The transverse homogeneity of the magnetic field integral is another strong design constraint. Good homogeneity was reached by optimizing the profiles of the iron poles. Eight steerers have been constructed and magnetic measurements have been performed.

High harmonics focusing undulator

Energy Technology Data Exchange (ETDEWEB)

Varfolomeev, A.A.; Hairetdinov, A.H.; Smirnov, A.V.; Khlebnikov, A.S. [Kurchatov Institute, Moscow (Russian Federation)

1995-12-31

It was shown in our previous work that there exist a possibility to enhance significantly the {open_quote}natural{close_quote} focusing properties of the hybrid undulator. Here we analyze the actual undulator configurations which could provide such field structure. Numerical simulations using 2D code PANDIRA were carried out and the enhanced focusing properties of the undulator were demonstrated. The obtained results provide the solution for the beam transport in a very long (short wavelength) undulator schemes.

Development of cryogenic permanent magnet undulator

International Nuclear Information System (INIS)

Hara, Toru; Tanaka, Takashi; Shirasawa, Katsutoshi; Kitamura, Hideo; Bizen, Teruhiko; Seike, Takamitsu; Marechal, Xavier; Tsuru, Rieko; Iwaki, Daisuke

2005-01-01

A short period undulator increases not only the photon energy of undulator radiation, but also the brilliance due to its increased number of undulator periods. As a result, brilliant undulator radiation becomes available in the photon energy range, which is currently covered by wigglers. In order to develop a short period undulator, high performance magnets are indispensable and superconductive undulators have been actively investigated in recent years. In this paper, however, we propose a new approach, so called a cryogenic permanent magnet undulator using NdFeB magnets at the temperatures around 150 K. The current status of this cryogenic permanent magnet undulator development at SPring-8 is presented including the results of the magnetic field measurements on a prototype undulator. (author)

The Canadian Gravity Geoid

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A detailed gravimetric geoid has been computed on a 10' by 10' grid for Canada by the University of New Brunswick. This data base was received in April 1989....

Simulations of laser undulators

Science.gov (United States)

Milton, S. V.; Biedron, S. B.; Einstein, J. E.

2016-09-01

We perform a series of single-pass, one-D free-electron laser simulations based on an electron beam from a standard linear accelerator coupled with a so-called laser undulator, a specialized device that is more compact than a standard undulator based on magnetic materials. The longitudinal field profiles of such lasers undulators are intriguing as one must and can tailor the profile for the needs of creating the virtual undulator. We present and discuss several results of recent simulations and our future steps.

Design and performance of the APPLE-Knot undulator

International Nuclear Information System (INIS)

Ji, Fuhao; Chang, Rui; Zhou, Qiaogen; Zhang, Wei; Ye, Mao; Sasaki, Shigemi; Qiao, Shan

2015-01-01

The design and performance of the Apple-Knot undulator which can generate photons with arbitrary polarization and low on-axis heat load are presented. Along with the development of accelerator technology, synchrotron emittance has continuously decreased. This results in increased brightness, but also causes a heavy heat load on beamline optics. Recently, optical surfaces with 0.1 nm micro-roughness and 0.05 µrad slope error (r.m.s.) have become commercially available and surface distortions due to heat load have become a key factor in determining beamline performance, and heat load has become a serious problem at modern synchrotron radiation facilities. Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported

Design and performance of the APPLE-Knot undulator

Energy Technology Data Exchange (ETDEWEB)

Ji, Fuhao [Department of Physics, State Key Laboratory of Surface Physics, and Laboratory of Advanced Materials, Fudan University, 2005 Songhu Road, Shanghai 200438, People’s Republic of (China); Chang, Rui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of (China); Zhou, Qiaogen; Zhang, Wei [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Shanghai 201204, People’s Republic of (China); Ye, Mao [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of (China); Sasaki, Shigemi [Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Hiroshima 739-0046 (Japan); Qiao, Shan, E-mail: qiaoshan@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of (China); School of Physical Science and Technology, ShanghaiTech University, 319 Yueyang Road, Shanghai 200031, People’s Republic of (China)

2015-06-09

The design and performance of the Apple-Knot undulator which can generate photons with arbitrary polarization and low on-axis heat load are presented. Along with the development of accelerator technology, synchrotron emittance has continuously decreased. This results in increased brightness, but also causes a heavy heat load on beamline optics. Recently, optical surfaces with 0.1 nm micro-roughness and 0.05 µrad slope error (r.m.s.) have become commercially available and surface distortions due to heat load have become a key factor in determining beamline performance, and heat load has become a serious problem at modern synchrotron radiation facilities. Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.

The direct effect on geoid computations

OpenAIRE

Juan G. Serpas

2016-01-01

La técnica más popular para la reducción de observaciones gravimétricas al geoide es el método de condensación de Helmert. Dos maneras deferentes de aplicar dicha reducción son estudiadas: el enfoque clásico (Wang y Rapp, 1990, Heiskanen y Morits, 1967) y el enfoque por Vanicek and Kleusberg (1987), extendido por Martinec et al. (1993). El enfoque clásico (Wang y Rapp, 1990, Heiskanen y Moritz, 1967) argumenta que el efecto de la capa condensada tiene que ser evaluado en el geoide y no en el ...

Flux shunts for undulators

International Nuclear Information System (INIS)

Hoyer, E.; Chin, J.; Hassenzahl, W.V.

1993-05-01

Undulators for high-performance applications in synchrotron-radiation sources and periodic magnetic structures for free-electron lasers have stringent requirements on the curvature of the electron's average trajectory. Undulators using the permanent magnet hybrid configuration often have fields in their central region that produce a curved trajectory caused by local, ambient magnetic fields such as those of the earth. The 4.6 m long Advanced Light Source (ALS) undulators use flux shunts to reduce this effect. These flux shunts are magnetic linkages of very high permeability material connecting the two steel beams that support the magnetic structures. The shunts reduce the scalar potential difference between the supporting beams and carry substantial flux that would normally appear in the undulator gap. Magnetic design, mechanical configuration of the flux shunts and magnetic measurements of their effect on the ALS undulators are described

Airborne gravimetry used in precise geoid computations by ring integration

DEFF Research Database (Denmark)

Kearsley, A.H.W.; Forsberg, René; Olesen, Arne Vestergaard

1998-01-01

Two detailed geoids have been computed in the region of North Jutland. The first computation used marine data in the offshore areas. For the second computation the marine data set was replaced by the sparser airborne gravity data resulting from the AG-MASCO campaign of September 1996. The results...... of comparisons of the geoid heights at on-shore geometric control showed that the geoid heights computed from the airborne gravity data matched in precision those computed using the marine data, supporting the view that airborne techniques have enormous potential for mapping those unsurveyed areas between...

Experience on the operation of the 2-in-1 electromagnetic undulator of FELICITA I

International Nuclear Information System (INIS)

Geisler, A.; Noelle, D.; Ridder, M.

1995-01-01

The 5m-Undulator of FELICITA I has been installed at the final position in the storage ring DELTA in spring 95. Detailed magnetic measurements have been performed in place to get a complete characterization of this device in both possible modes, pure undulator and optical klystron mode, respectively. The undulator consists of 38 identic poles. Four power supplies are connected to the main coils. Three of them drive the central six poles to get the dispersive section with its matching to the outer undulator sections. This setup allows a change between the optical klystron and the pure undulator mode without changing the hardware. For measuring the magnetic field components a hall-probe was used. It was found that correction coils for compensating peak field variations were not necessary, because of errors less then 0.2 %. Only for the purpose of steering correction coils had to be used. The field integrals were also measured with the pulsed-wire technique. For fast response concerning the matching, in particular of the dispersive section this technique was found to be very useful. Because of the large period length of 25 cm the wire sag in the rather long undulator could be neglected

Proposed particle-beam characterizations for the APS undulator test line

Energy Technology Data Exchange (ETDEWEB)

Lumpkin, A.H.; Borland, M.; Milton, S.

1993-09-01

A research and development effort is underway at the Advanced Photon Source (APS) to use an rf gun as a low-emittance electron source for injection into the 100- to 650-MeV linac subsystem and subsequently to an undulator test area. This configuration would combine the acceleration capability of the 200-MeV S-band electron linac and the in-line 450-MeV positron linac that normally provide positrons to the positron accumulator ring (PAR). A transport line that bypasses the PAR will bring the electrons to the undulator test area. Characterization techniques will be discussed for the electron beam with a normalized, rms emittance of <10 {pi} mm mrad (1{sigma}) at micropulse charges of up to 350 pC and micropulse durations of {approximately}5 ps (FWHM). Tests proposed include measurement of particle beam transport effects (at one-tenth the storage ring beam rigidity) caused by small undulator field errors as well as operations intended to produce coherent, short wavelength radiation (<200 nm).

Subducted slabs and lateral viscosity variations: effects on the long-wavelength geoid

Science.gov (United States)

Tosi, Nicola; Čadek, Ondřej; Martinec, Zdeněk

2009-11-01

The characteristic broad local maxima exhibited by the long-wavelength geoid over subduction zones are investigated with a numerical model of mantle flow. In a spherical axisymmetric geometry, a synthetic model of buoyancy driven subduction is used to test the effects on the geoid caused by the depth of penetration of the lithosphere into the mantle, by the viscosity stratification and by lateral viscosity variations (LVV) in the lithosphere, upper and lower mantle. The presence of anomalous slab density in the lower mantle guarantees geoid amplitudes comparable with the observations, favouring the picture of slabs that penetrate the transition zone and sink into the deep mantle. The viscosity of the lower mantle controls the long-wavelength geoid to the first order, ensuring a clear positive signal when it is at least 30-times greater than the upper-mantle viscosity. The presence of LVV in the lithosphere, in the form of weak plate margins, helps to increase the contribution of the surface topography, causing a pronounced reduction of the geoid. Localized LVV associated with the cold slab play a secondary role if they are in the upper mantle. On the other hand, highly viscous slabs in the lower mantle exert a large influence on the geoid. They cause its amplitude to increase dramatically, way beyond the values typically observed over subduction zones. Long-wavelength flow becomes less vigorous as the slab viscosity increases. Deformation in the upper mantle becomes more localized and power is transferred to short wavelengths, causing the long-wavelength surface topography to diminish and the total geoid to increase. Slabs may be then weakened in the lower mantle or retain their high viscosity while other mechanisms act to lower the geoid. It is shown that a phase change from perovskite to post-perovskite above the core-mantle boundary can cause the geoid to reduce significantly, thereby helping to reconcile models and observations.

Geoid Height and Deflections of the Vertical Models - National Geospatial Data Asset (NGDA) Geoid Models

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In Gauss' words, the geoid is "the mathematical figure of the Earth". This figure is an equipotential surface coincident with the idealized mean sea surface. The...

Satellite-derived geoid for the estimation of lithospheric cooling and ...

Indian Academy of Sciences (India)

The northern Indian Ocean consists of older Bay of Bengal (BOB) oceanic .... Andaman & Nicobar Islands m ... The long wavelength classical geoid anomaly over the northern Indian Ocean with the largest geoid anomaly low ... and 'Snm' are the mass distribution functions. ..... in the Pacific Plate that caused the long wave-.

An electromagnetic micro-undulator

International Nuclear Information System (INIS)

Nassiri, A.; Turner, L.R.

1997-01-01

Microfabrication technology using the LIGA (a German acronym for Lithography, Electroforming, and Molding) process offers an attractive alternative for fabricating precision devices with micron-sized features. One such device is a mm-sized micro-undulator with potential applications in a table-top synchrotron light source for medical and other industrial uses. The undulator consists of a silver conductor embedded in poles and substrate of nickel-iron. Electromagnetic modeling of the undulator is done using the eddy current computer code ELEKTRA. Computations predict a field pattern of appropriate strength and quality if the current can be prevented from being shunted from silver by the nickel-iron poles either through insulation or through slotted poles. The design of the undulator along with the computational results are discussed

A Helical Undulator Wave-guide Inverse Free-Electron Laser

International Nuclear Information System (INIS)

Rosenzweig, J.; Bodzin, N.; Frigola, P.; Musumeci, P.; Pellegrini, C.; Travish, G.; Joshi, C.; Tochitsky, S.

2004-01-01

With recent success in high gradient, high-energy gain IFEL experiments at the UCLA Neptune Laboratory, future experiments are now being contemplated. The Neptune IFEL was designed to use a tightly focused, highly diffracting, near-TW peak power 10 micron laser. This choice of laser focusing, driven by power-handling limitations of the optics near the interaction region, led to design and use of a very complex undulator, and to sensitivity to both laser misalignment and focusing errors. As these effects limited the performance of the IFEL experiment, a next generation experiment at Neptune has been studied which avoids the use of a highly diffractive laser beam through use of a waveguide. We discuss here the choice of low-loss waveguide, guided mode characteristics and likely power limitations. We also examine a preferred undulator design, which is chosen to be helical in order to maximize the acceleration achieved for a given power. With the limitations of these laser and undulator choices in mind, we show the expected performance of the IFEL using 1D simulations. Three-dimensional effects are examined, in the context of use of a solenoid for focusing and acceleration enhancement

Numerical Modeling of Shoreline Undulations

DEFF Research Database (Denmark)

Kærgaard, Kasper Hauberg

model has been developed which describes the longshore sediment transport along arbitrarily shaped shorelines. The numerical model is based on a spectral wave model, a depth integrated flow model, a wave-phase resolving sediment transport description and a one-line shoreline model. First the theoretical...... of the feature and under predicts the migration speeds of the features. On the second shoreline, the shoreline model predicts undulations lengths which are longer than the observed undulations. Lastly the thesis considers field measurements of undulations of the bottom bathymetry along an otherwise straight...... length of the shoreline undulations is determined in the linear regime using a shoreline stability analysis based on the numerical model. The analysis shows that the length of the undulations in the linear regime depends on the incoming wave conditions and on the coastal profile. For larger waves...

Alignment of the VISA Undulator

International Nuclear Information System (INIS)

Ruland, Robert E.

2000-01-01

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 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

Some new ideas about undulators

International Nuclear Information System (INIS)

Halbach, K.

1985-11-01

There are still no helical undulators that satisfy all major requirements. A new helical undulator is described that has at least some of the properties that were not obtainable until now. It can be used in a synchrotron storage ring, is completely accessible from both sides, light with both helicities can be produced, the helical field can be made quite strong, and the period length can be adjusted over a small range. Similarly, there have been some efforts lately to develop undulators with very short periods. It is shown how a hybrid undulator with a period of the order 1 mm can be constructed

Precisión de la aproximación geoide y geoestadística: cómo encontrar un mapa contínuo de datos de gravedad absoluta

Directory of Open Access Journals (Sweden)

Hongzhi Song

2015-10-01

Full Text Available An accurate geoid model is needed for surveyors and engineers who require orthometric heights on a common datum, and environ- ment scientists who require elevations relative to present sea level. Airborne gravity data has been collected by the National Geodetic Survey (NGS under the Gravity for the Redefinition of the Amer- ican Vertical Datum (GRAV-D project and is available along the coasts of the Gulf of Mexico. For this study we obtained a set of abso- lute gravity data derived from full-field gravity at altitude/elevation. We used the data to derive free-air gravity anomalies to establish gravity on the geoid. For spatial interpolation we used the kriging method to estimate gravity on the geoid in any location and krig- ing of the difference between gravity on the ellipsoid of reference and the geoid. Various kriging methods were used for evaluation of errors calculated in this study. The mean precision of the predicted val- ues is around 1.23 cm, a very good result for coastal regions, which traditionally have sparse gravity data sets.

GRAVTool, a Package to Compute Geoid Model by Remove-Compute-Restore Technique

Science.gov (United States)

Marotta, G. S.; Blitzkow, D.; Vidotti, R. M.

2015-12-01

Currently, there are several methods to determine geoid models. They can be based on terrestrial gravity data, geopotential coefficients, astro-geodetic data or a combination of them. Among the techniques to compute a precise geoid model, the Remove-Compute-Restore (RCR) has been widely applied. It considers short, medium and long wavelengths derived from altitude data provided by Digital Terrain Models (DTM), terrestrial gravity data and global geopotential coefficients, respectively. In order to apply this technique, it is necessary to create procedures that compute gravity anomalies and geoid models, by the integration of different wavelengths, and that adjust these models to one local vertical datum. This research presents a developed package called GRAVTool based on MATLAB software to compute local geoid models by RCR technique and its application in a study area. The studied area comprehends the federal district of Brazil, with ~6000 km², wavy relief, heights varying from 600 m to 1340 m, located between the coordinates 48.25ºW, 15.45ºS and 47.33ºW, 16.06ºS. The results of the numerical example on the studied area show the local geoid model computed by the GRAVTool package (Figure), using 1377 terrestrial gravity data, SRTM data with 3 arc second of resolution, and geopotential coefficients of the EIGEN-6C4 model to degree 360. The accuracy of the computed model (σ = ± 0.071 m, RMS = 0.069 m, maximum = 0.178 m and minimum = -0.123 m) matches the uncertainty (σ =± 0.073) of 21 points randomly spaced where the geoid was computed by geometrical leveling technique supported by positioning GNSS. The results were also better than those achieved by Brazilian official regional geoid model (σ = ± 0.099 m, RMS = 0.208 m, maximum = 0.419 m and minimum = -0.040 m).

The properties of undulator radiation

International Nuclear Information System (INIS)

Howells, M.R.; Kincaid, B.M.

1993-09-01

A new generation of synchrotron radiation light sources covering the VUV, soft x-ray, and hard x-ray spectral regions is under construction in several countries. These sources are designed specifically to use periodic magnetic undulators and low-emittance electron or positron beams to produce high-brightness near-diffraction-limited synchrotron radiation beams. Some of the novel features of the new sources are discussed, along with the characteristics of the radiation produced, with emphasis on the Advanced Light Source, a third-generation 1.5 GeV storage ring optimized for undulator use. A review of the properties of undulator radiation is presented, followed by a discussion of some of the unique challenges being faced by the builders and users of the new undulator sources. These include difficult mechanical and magnetic tolerance limits, a complex interaction with the storage ring, high x-ray beam power, partial coherence, harmonics, optics contamination, and the unusual spectral and angular properties of undulator radiation

A new formulation of Stokes’ approach in determining the global gravimetric geoid

Directory of Open Access Journals (Sweden)

Wen-Bin Shen

2013-08-01

Full Text Available According to Stokes’ approach, given the gravity anomaly on the geoid as the boundary, a disturbing potential function satisfying some boundary conditions should be solved. The basic requirement is that the disturbing potential function should be harmonic in the region outside the geoid. However, since the normal gravity potential is not defined inside the reference ellipsoid (taking the WGS84 ellipsoid as an example, when the geoid is below the ellipsoidal surface, the disturbing potential function is not harmonic in the whole region outside the geoid, and is not defined on the whole geoid itself. These are theoretical difficulties in Stokes’ approach. To remove these difficulties from Stokes’ approach, this study provides a new formulation of Stokes’ approach. An inner ellipsoid with four fundamental parameters is chosen, two of which, the geocentric gravitational constant and the rotational angular velocity, coincide with the corresponding parameters of the WGS84 ellipsoid. The other two parameters, the semi-major axis and flattening, are different from the corresponding ones of the ellipsoid. Then, the normal gravity potential generated by the inner ellipsoid is determined, by requiring that it holds a constant on the surface of the inner ellipsoid or on the surface of the ellipsoid. With this new formulation, the disturbing potential function is harmonic in the whole region outside the geoid, and the difficulties in Stokes’ approach disappear. The new formulation proposed in this study is also adequate for analogous geodetic boundary-value problems.

Undulator A diagnostics at the Advanced Photon Source

International Nuclear Information System (INIS)

Ilinski, P.

1998-01-01

Diagnostics of Undulator A number-sign 2 (UA2) radiation was performed during the October 1997 mn at the Advanced Photon Source (APS). The UA2 undulator is a standard 3.3-cm-period APS Undulator A, which was positioned downstream from the center of the straight section at Sector 8. The diagnostics included the angular-spectral measurements of the undulator radiation to determine the undulator radiation absolute spectral flux and the particle beam divergence. The results of the absolute spectral flux measurements are compared to the undulator spectrum calculated from measured undulator magnetic field. The particle's energy spread was determined from spectra comparison. Previously, the authors reported the first measurements made on Undulator A at the APS. The purpose of the present report is to summarize the results of the diagnostics performed on the Sector 8 undulator at the request of the IMM-CAT staff, and to present a more general discussion of undulator radiation sources at the APS and details of their diagnostics

Tapered undulators for SASE FELs

CERN Document Server

Fawley, W M; Vinokurov, N A

2002-01-01

We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

Deep structure of the Tristan-Gough plume revealed by geoid anomalies

Science.gov (United States)

Maia, M.; Flamme, J.; Cadio, C.; Lalancette, M. F.; Metivier, L.; Pajot-Métivier, G.; Diament, M.

2017-12-01

The origin of the hotspot Tristan da Cunha located at the southwestern end of Walvis Ridge in the Atlantic Ocean is still a controversial topic. We especially question on the nature of the involved geodynamical processes and on their origin depth. The latest results based on local seismic and magnetic data (Schlömer et al., 2016; Baba et al., 2016; Geissler et al., 2016) suggest the existence of a plume coming from the mid-mantle in the southwest of the archipelago. Here we give a regional view of mantle dynamics patterns in the area by using the high-quality satellite geoid data. To extract the mantle signature, we estimate the crustal and lithospheric signals of the ocean basin and South American and African continents, which contribute to mid- and long-wavelengths in the total geoid. We pay particular attention to the modeling of continental margins and their effects on the residual geoid signal. In addition, we explore a large density values set derived from petrological and geochemical studies in the calculation of the lithospheric geoid model. After subtracting the lithospheric signature to the EGM2008 geoid, we apply a multi-scale analysis, which unfolds the different components of the geoid residual signal. The analysis underlines a set of positive anomalies at 200-400 km in the study area, notably in north and west of Tristan de Cunha, and a positive anomaly at 700-1100 km scale in the southwest of the archipelago. These patterns do not change by using different lithospheric geoid models, which allow us to evaluate the reliability of the residual geoid anomalies. These results indicate the existence of small-scale density anomalies in the upper mantle and a larger scale density anomaly in the mid-mantle. Our study suggests that a large dome toped by plume clusters could be a good candidate to explain the volcanism of Tristan da Cunha.Schlömer et al., 2016 Hunting for the Tristan mantle plume..., EPSL, http://dx.doi.org/10.1016/j.epsl.2016.12.028Baba et

Status of the LCLS-II undulators

Energy Technology Data Exchange (ETDEWEB)

Wallén, E., E-mail: ejwallen@lbl.gov; Arbelaez, D.; Brown, A.; Dougherty, J.; Corlett, J.; DeMello, A.; Hanzel, K.; Jung, J.-Y.; Leitner, M.; Madur, A.; McCombs, K.; Marks, S.; Munson, D.; Plate, D.; Pucci, J.; Ray, K.; Schlueter, R.; Mateo, E. San [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); D’Ewart, M.; Rowen, M. [SLAC National Accelerator Laboratory 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

2016-07-27

The new free electron laser facility Linear Coherent Light Source II (LCLS-II) under construction at SLAC National Accelerator Laboratory will use planar variable gap undulators of hybrid type for the production of free electron laser (FEL) radiation. The LCLS-II will include two FELs with two separate rows of undulators to generate soft and hard x-rays. The soft x-rays will be produced by undulators with 39 mm period length (SXR) and the hard x-rays will be produced by undulators with 26 mm period length (HXR). Both the SXR and the HXR undulators are 3.4 m long and they use a common support structure and frame. In total 21 SXR and 32 HXR undulators will be produced by Lawrence Berkeley National Laboratory in collaboration with SLAC National Accelerator Laboratory. A full-scale prototype with 32 mm period length, called HXU, has been assembled at Lawrence Berkeley National Laboratory (LBNL). The present status of the design, prototyping, and pre-series production of the SXR and HXR undulators are presented in this paper together with the first results from measurements on the full scale HXU prototype.

Transition undulator radiation as bright infrared sources

Energy Technology Data Exchange (ETDEWEB)

Kim, K.J. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

Undulator radiation contains, in addition to the usual component with narrow spectral features, a broad-band component in the low frequency region emitted in the near forward direction, peaked at an angle 1/{gamma}, where {gamma} is the relativistic factor. This component is referred to as the transition undulator radiation, as it is caused by the sudden change in the electron`s longitudinal velocity as it enters and leaves the undulator. The characteristic of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.

Geoid-to-Quasigeoid Separation Computed Using the GRACE/GOCE Global Geopotential Model GOCO02S - A Case Study of Himalayas and Tibet

Directory of Open Access Journals (Sweden)

Mohammad Bagherbandi Robert Tenzer

2013-01-01

Full Text Available The geoid-to-quasigeoid correction has been traditionally computed approximately as a function of the planar Bouguer gravity anomaly and the topographic height. Recent numerical studies based on newly developed theoretical models, however, indicate that the computation of this correction using the approximate formula yields large errors especially in mountainous regions with computation points at high elevations. In this study we investigate these approximation errors at the study area which comprises Himalayas and Tibet where this correction reaches global maxima. Since the GPS-leveling and terrestrial gravity datasets in this part of the world are not (freely available, global gravitational models (GGMs are used to compute this correction utilizing the expressions for a spherical harmonic analysis of the gravity field. The computation of this correction can be done using the GGM coefficients taken from the Earth Gravitational Model 2008 (EGM08 complete to degree 2160 of spherical harmonics. The recent studies based on a regional accuracy assessment of GGMs have shown that the combined GRACE/GOCE solutions provide a substantial improvement of the Earth¡¦s gravity field at medium wavelengths of spherical harmonics compared to EGM08. We address this aspect in numerical analysis by comparing the gravity field quantities computed using the satellite-only combined GRACE/GOCE model GOCO02S against the EGM08 results. The numerical results reveal that errors in the geoid-to-quasigeoid correction computed using the approximate formula can reach as much as ~1.5 m. We also demonstrate that the expected improvement of the GOCO02S gravity field quantities at medium wavelengths (within the frequency band approximately between 100 and 250 compared to EGM08 is as much as ±60 mGal and ±0.2 m in terms of gravity anomalies and geoid/quasigeoid heights respectively.

Multi-mission mean sea surface and geoid models for ocean monitoring within the GOCINA project

Science.gov (United States)

Andersen, O. B.; Knudsen, P.; Anne, V. L.

2004-05-01

A major goal of the EU project GOCINA (Geoid and Ocean Circulation In the North Atlantic) is to develop tools for ocean monitoring using satellite altimetry combined with satellite gravimetry. Furthermore, the project will determine an accurate geoid in the region between Greenland and the UK and, hereby, create a platform for validation of future GOCE Level 2 data and higher order scientific products. The central quantity bridging the geoid and the ocean circulation is the mean dynamic topography, which is the difference between the mean sea surface and the geoid. The mean dynamic topography provides the absolute reference surface for the ocean circulation. The improved determination of the mean circulation will advance the understanding of the role of the ocean mass and heat transport in climate change. To calculate the best possible synthetic mean dynamic topographies a new mean sea surface (KMS03) has been derived from nine years of altimetric data (1993-2001). The regional geoid has furthermore being updated using GRACE and gravimetric data from a recent airborne survey. New synthetic mean dynamic topography models have been computed from the best available geoid models (EGM96, GRACE, GOCINA) and the present mean sea surface models (i.e. CLS01, GSFC00, KMS03). These models will be compared with state of the art hydrodynamic mean dynamic topography models in the North Atlantic GOCINA area. An extended comparison in the Artic Ocean will also be presented to demonstrate the impact of improved geoid and mean sea surface modeling. Particularly using the GRACE derived geoid models, and the KMS03 mean sea surface.

Diffusion effects in undulator radiation

Directory of Open Access Journals (Sweden)

Ilya Agapov

2014-11-01

Full Text Available Quantum diffusion effects in undulator radiation in semiclassical approximation are considered. Short-term effects on the electron beam motion are discussed and it is shown that approaches based on diffusion approximation with drift-diffusion coefficients derived from undulator or bending magnet radiation spectrum, and on Poisson statistics with radiation spectrum defined by the local beding field, all lead to similar results in terms of electron energy spread for cases of practical interest. An analytical estimate of the influence of quantum diffusion on the undulator radiation spectrum is derived.

MaRIE Undulator & XFEL Systems

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Dinh Cong [Los Alamos National Laboratory; Marksteiner, Quinn R. [Los Alamos National Laboratory; Anisimov, Petr Mikhaylovich [Los Alamos National Laboratory; Buechler, Cynthia Eileen [Los Alamos National Laboratory

2015-03-23

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.

Learning-based computing techniques in geoid modeling for precise height transformation

Science.gov (United States)

Erol, B.; Erol, S.

2013-03-01

Precise determination of local geoid is of particular importance for establishing height control in geodetic GNSS applications, since the classical leveling technique is too laborious. A geoid model can be accurately obtained employing properly distributed benchmarks having GNSS and leveling observations using an appropriate computing algorithm. Besides the classical multivariable polynomial regression equations (MPRE), this study attempts an evaluation of learning based computing algorithms: artificial neural networks (ANNs), adaptive network-based fuzzy inference system (ANFIS) and especially the wavelet neural networks (WNNs) approach in geoid surface approximation. These algorithms were developed parallel to advances in computer technologies and recently have been used for solving complex nonlinear problems of many applications. However, they are rather new in dealing with precise modeling problem of the Earth gravity field. In the scope of the study, these methods were applied to Istanbul GPS Triangulation Network data. The performances of the methods were assessed considering the validation results of the geoid models at the observation points. In conclusion the ANFIS and WNN revealed higher prediction accuracies compared to ANN and MPRE methods. Beside the prediction capabilities, these methods were also compared and discussed from the practical point of view in conclusions.

Image tuning techniques for enhancing the performance of pure permanent magnet undulators with small gap/period ratios

Energy Technology Data Exchange (ETDEWEB)

Tatchyn, R. [Stanford Univ., CA (United States)

1995-12-31

The on-axis field of a small-gap undulator constricted out of pure permanent magnet (PM) blocks arranged in an alternating-dipole (i.e., 2 dipoles/period) array can be substantially varied by positioning monolithic permeable plates above and below the undulator jaws. This simple technique, which can be used to control the 1st harmonic energy in conventional synchrotron radiation (SR) or Free Electron Laser (FEL) applications requiring sub-octave tuning, can also be shown to suppress magnetic inhomogeneities that can contribute to the undulator`s on-axis field errors. If a standard 4 block/period Halbach undulator, composed of PM blocks with square cross sections, is rearranged into an alternating-dipole array with the same period, the peak field that can be generated with superimposed image plates can substantially exceed that of the pure-PM Halbach array. This design technique, which can be viewed as intermediate between the {open_quotes}pure-PM{close_quotes} and standard {open_quotes}hybrid/PM{close_quotes} configurations, provides a potentially cost-effective method of enhancing the performance of small-gap, pure-PM insertion devices. In this paper we report on the analysis and recent characterization of pure-PM undulator structures with superimposed image plates, and discuss possible applications to FEL research.

First lasings at IR-and FIR range using hybrid type undulator (FEL facility 4) and Halbach type undulator

International Nuclear Information System (INIS)

Takii, T.; Oshita, E.; Okuma, S.; Wakita, K.; Koga, A.; Tomimasu, T.; Ohasi, K.

1997-01-01

First lasing at 18μm was achieved by using a 2.7-m long hybrid type undulator (undulator 4) for far-infrared FELs and a 6.72-m long optical cavity installed at the 33-MeV beam line of the downstream of the FEL facility 1 (FEL-1). We are challenged at two-color FEL oscillation in mid-infrared range using the undulator 1 (λ u=3.4mm) and in far-infrared range using the undulator 4 (λ u=9mm). At first, a 30-MeV, 60-A beam passed through the undulator 1 without lasing is transported using a QFQDBQFQDBQFQDQF system and is used for lasing at the undulator 4. However, six pairs of steering coils had to be attached on the beam duct to reduce the deviation of the electron beam trajectory due to the vertical field distribution induced by the built-in electromagnets. The minimum gap of the undulator 4 was designed to be 35mm. However, the steering coils attached on the beam duct increased the gap up to 52mm. Therefore, the hybrid type undulator was replaced by a new Halbach type one (λ u=8mm, N=30) after the first lasing at 18μm on October 24, '96. The New FEL facility 4 was installed in the middle of December and first lasing at 18.6μm was achieved on December 26, within 10 hours operation. (author)

ON THE COMPUTATION OF A PRECISE GEOID – TO – QUASIGEOID SEPARATION

Directory of Open Access Journals (Sweden)

S. Hejrati

2017-09-01

Full Text Available In geodesy, orthometric and normal heights are considered as basic height systems on the earth. The reference surfaces for these heights are the geoid and quasigeoid respectively. Taking advantage of GNSS measurements, one can achieve a precise solution for the geoid and for the quasigeoid. Two methods, called direct and indirect, are worked out in this research for the computation of separation between geoid and quasigeoid in a mountainous region in the USA. The area selected for this purpose is mountainous and rough enough in order to be able to show the effect of roughness of topography in the sought quantity. The results of the two methods and testing them against GNSS-Levelling on 445 known points indicates an accuracy of 1.3 cm in RMS scale with the direct method, where there is 7 cm as an average difference between the observed geoid and quasigeoid separation and the same quantity derived from the direct method. Using Chi-squared goodness of fit test showed that the distribution of the residual quantities are normally distributed in the test area.

Experience with small-gap undulators

International Nuclear Information System (INIS)

Stefan, P.; Krinsky, S.

1996-01-01

Small-gap undulators offer enhanced performance as synchrotron radiation sources, by providing extended tuning range and the possibility of higher photon energies via short-period, small-gap devices. Challenges associated with the operation of small-gap undulators arise from their requirement for small beam apertures and the resulting possibility of lifetime degradation, beam instabilities, and radiation hazards. To investigate these fundamental limitations, we have constructed an R ampersand D small-gap undulator for the X13 straight section of the NSLS 2.584 GeV X-ray Ring and have tested it during studies shifts and normal user shifts during the last year. This device, the NSLS prototype small-gap undulator (PSGU), consists of a variable-aperture vacuum chamber and a 16-mm-period pure-permanent-magnet undulator, both mounted to a common elevator base stage. The design output spectrum of 2.5 keV in the fundamental (and 7.5 keV in the third harmonic) was obtained with a magnet gap of 5.6 mm and an electron beam aperture of 2.5 mm. The partial lifetime contribution for these parameters was observed to be about 40 hr. Details of the synchrotron radiation output spectrum, lifetime dependence on aperture, and bremsstrahlung radiation production will be presented. copyright 1996 American Institute of Physics

Evaluation of EGM2008 by means of GPS Levelling Uganda | Abeho ...

African Journals Online (AJOL)

For testing the model, a total of seven levelled benchmarks available in Uganda which belong to the New Khartoum datum were used. The spatial positions of these benchmarks were determined at mm accuracy, with respect to ITRF2008. The agreement between the EGM2008 geoid and the geoid undulation derived from ...

Undulator systems for the TESLA X-FEL

International Nuclear Information System (INIS)

Pflueger, J.; Tischer, M.

2002-01-01

A large X-ray FEL lab is under consideration within the TESLA project and is supposed to be operated in parallel with the TESLA linear collider. There will be five SASE FELs and five conventional spontaneous undulators. A conceptual design study has been made for the undulator systems for these X-FELs. It includes segmentation into 6.1 m long undulator 'cells'. Each consists of a 5 m long undulator 'segment', a separate quadrupole, one horizontal and one vertical corrector, and a phase shifter. These items are presented and discussed

Cryogenic Permanent Magnet Undulators

International Nuclear Information System (INIS)

Chavanne, J.; Lebec, G.; Penel, C.; Revol, F.; Kitegi, C.

2010-01-01

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 2 Co 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 undulator 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.

PRELIMINARY GEOID MODEL IN SAN JUAN PROVINCE: A CASE STUDY IN THE ANDES

DEFF Research Database (Denmark)

Tocho, Claudia; Miranda, Silvia; Pacino, Maria Cristina

2008-01-01

A high-resolution and high-precision detailed gravimetric geoid has been computed for San Juan province in Argentina, ranging from 27 degrees S to 34 degrees S in latitude and 72 degrees W to 65 degrees W in longitude. The gravimetric geoid was calculated using the RTM method, a multiband spheric...

Investigation of the nonlinear effects of Wiggler and undulator fields on the beam dynamics of particle storage rings in the case of DORIS III

International Nuclear Information System (INIS)

Decking, W.

1995-11-01

In this thesis I analyze the effects of wiggler and undulator magnetic fields on the beam dynamics of electron/positron storage rings. DORIS III, DESY's synchrotron radiation source is taken as an example. Wigglers and undulators are used for the production of synchrotron radiation or to control beam sizes in storage rings. Their introduction in the lattices of storage rings causes some problems due to the strong nonlinearities of the magnetic fields. Therefore a detailed analysis of the particle dynamics under the influence of wiggler magnetic fields and their field errors is necessary. This thesis provides such an analysis. The problem will be attacked analytically, numerically and experimentally. The analytic approach is based on the treatment of the appropriate Hamiltonian with perturbation theory. The magnetic fields are described with a Fourier series, which covers the main characteristics of wiggler and undulator fields. The main effect of wigglers and undulators is the excitation of fourth order synchro-betatron resonances. The description of field errors and other details of the magnetic fields is achieved by integrating over appropriately distributed current sheets. This allows the modeling of different parameters such as magnet pole width, periodicity errors and errors in the field gradients. (orig./WL)ons of motion in the fields calculated with this method can only be integrated numerically. This would be much too slow to be used in particle tracking codes. Therefore a transfer map b

Vacuum systems for the ILC helical undulator

CERN Document Server

Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A

2007-01-01

The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

Magnetic Measurement Results of the LCLS Undulator Quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Anderson, Scott; Caban, Keith; Nuhn, Heinz-Dieter; Reese, Ed; Wolf, Zachary; /SLAC

2011-08-18

This note details the magnetic measurements and the magnetic center fiducializations that were performed on all of the thirty-six LCLS undulator quadrupoles. Temperature rise, standardization reproducibility, vacuum chamber effects and magnetic center reproducibility measurements are also presented. The Linac Coherent Light Source (LCLS) undulator beam line has 33 girders, each with a LCLS undulator quadrupole which focuses and steers the beam through the beam line. Each quadrupole has main quadrupole coils, as well as separate horizontal and vertical trim coils. Thirty-six quadrupoles, thirty-three installed and three spares were, manufactured for the LCLS undulator system and all were measured to confirm that they met requirement specifications for integrated gradient, harmonics and for magnetic center shifts after current changes. The horizontal and vertical dipole trims of each quadrupole were similarly characterized. Each quadrupole was also fiducialized to its magnetic center. All characterizing measurements on the undulator quads were performed with their mirror plates on and after a standardization of three cycles from -6 to +6 to -6 amps. Since the undulator quadrupoles could be used as a focusing or defocusing magnet depending on their location, all quadrupoles were characterized as focusing and as defocusing quadrupoles. A subset of the undulator quadrupoles were used to verify that the undulator quadrupole design met specifications for temperature rise, standardization reproducibility and magnetic center reproducibility after splitting. The effects of the mirror plates on the undulator quadrupoles were also measured.

Spontaneous emission spectra from a staggered-array undulator

International Nuclear Information System (INIS)

Shimada, Shigeki; Okada, Kouji; Masuda, Kai; Sobajima, Masaaki; Yoshikawa, Kiyoshi; Ohnishi, Masami; Yamamoto, Yasushi; Toku, Hisayuki

1997-01-01

A staggered-array undulator set inside the superconducting solenoid coils is shown to be able to provide high undulator fields larger than the longitudinal magnetic fields, a small undulator period, easy tunability through the solenoid coil current, and compact and easy fabrication. The overall performance characteristics of this undulator were studied mainly with respect to iron and aluminum disk widths, and spontaneous emission spectra through the numerical calculations. The maximum undulator field is found to be obtained for the ratio of the aluminum disk width to the undulator period of 0.45. The line widths (FWHM) of the spontaneous emission spectra, however, do not show N w -1 dependence on the number of the undulator period N w for practical beams with a Gaussian distribution, compared with for a single electron. The energy spread among various parameters is seen to play an important role in reducing the FWHM with increase of N w . The large tunability of the wavelength is proved to cover 6-10 mm by changing the solenoid magnetic field from 0.4 T to 1.6 T. (author)

Effects of angular misalignment on optical klystron undulator radiation

Energy Technology Data Exchange (ETDEWEB)

Mishra, G., E-mail: gmishra_dauniv@yahoo.co.in; Prakash, Bramh; Gehlot, Mona

2015-11-21

In this paper ,we analyze the important effects of optical klystron undulator radiation with an angular offset of the relativistic electron beam in the second undulator section. An anlytical expression for the undulator radiation is obtained through a transparent and simple procedure.It is shown that the effects of the angular offset is more severe for longer undulator lengths and with higher dispersive field strengths.Both these effects are less pronounced for undulators with large K values.

Use of GOCE L2 Gravity Gradients for full resolution Geoid

DEFF Research Database (Denmark)

Herceg, Matija; Tscherning, Carl Christian; Knudsen, Per

The objective of this study is to develop methodology to use GOCE gravity gradients for enhanced geoid modelling and ocean circulation modelling. In specific regions with a rough gravity field, the resolution of the geoid may be enhanced substantially if GOCE gradiometer data are used in addition...... of the GOCE spherical harmonic coefficient model (EGMs) since in such areas the GOCE gradients contain more information than the EGM itself. Hence, the use of gradients may lead to improve the resolution of e.g. the marine geoid which in turn will improve the estimation of the ocean circulation....... This is tested using GOCE gravity gradient data, the GEOCOL program (GRAVSOFT) and Reduced Point Mass (RPM) program. Tests are carried out in the GOCINA region and in the Mediterranean basin. Furthermore, the effect of the decreasing height of the GOCE satellite on gravity gradients and associated MDT...

Oceanic Geoid and Tides Obtained from GEOS-3 Satellite Data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1978-01-01

Two sets of GEO-3 altimeter data which fall within about a 2.5 degree width are analyzed for ocean geoid and tides. One set covers a linear path from Newfoundland to Cuba and the other from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M sub 2 O sub 1, S sub 2, and K sub 1, are obtained along the two strips. The results demonstrate convergent solutions for all forty cases and show, within expectation, fair agreement with those obtained from the MODE deep-sea tide gauge. It is also shown that the oceanic geoid obtained through this analysis can potentially improve the short wavelength structure over existing geoid models.

The performance of a superconducting micro-undulator prototype

International Nuclear Information System (INIS)

Ben-Zvi, I.; Jiang, Z.Y.; Ingold, G.; Yu, L.H.; Sampson, W.B.

1990-05-01

We report on the performance of a prototype of a super-ferric micro-undulator. The micro-undulator consists of a continuous winding of niobium-titanium wire wound on a low carbon steel yoke. It is about 3 periods long with a period of 8.8 mm and a gap of 4.4 mm. The undulator achieves the a peak magnetic field on axis of over 0.5 Tesla. Asymmetry of the field pattern due to a dipole component was identified, analyzed and a correction has been applied to the undulator ends to produce a symmetric field distribution. Within the precision of the measurement the field pattern produced by the super-ferric undulator needed no correction. 4 refs., 7 figs

Advanced photon source low-energy undulator test line

International Nuclear Information System (INIS)

Milton, S.V.

1997-01-01

The injector system of the Advanced Photon Source (APS) consists of a linac capable of producing 450-MeV positrons or > 650-MeV electrons, a positron accumulator ring (PAR), and a booster synchrotron designed to accelerate particles to 7 GeV. There are long periods of time when these machines are not required for filling the main storage ring and instead can be used for synchrotron radiation research. We describe here an extension of the linac beam transport called the Low-Energy Undulator Test Line (LEUTL). The LEUTL will have a twofold purpose. The first is to fully characterize innovative, future generation undulators, some of which may prove difficult or impossible to measure by traditional techniques. These might include small-gap and superconducting undulators, very long undulators, undulators with designed-in internal focusing, and helical undulators. This technique also holds the promise of extending the magnetic measurement sensitivity beyond that presently attainable. This line will provide the capability to directly test undulators before their possible insertion into operating storage rings. A second use for the test line will be to investigate the generation of coherent radiation at wavelengths down to a few tens of nanometers

Generation of radiation by intense plasma and electromagnetic undulators

Energy Technology Data Exchange (ETDEWEB)

Joshi, C.

1991-10-01

We examine the characteristics of the classical radiation emission resulting from the interaction of a relativistic electron beam that propagates perpendicularly through a large amplitude relativistic plasma wave. Such a study is useful for evaluating the feasibility of using relativistic plasma waves as extremely short wavelength undulators for generating short wavelength radiation. The electron trajectories in a plasma wave undulator and in an ac FEL undulator are obtained using perturbation techniques. The spontaneous radiation frequency spectrum and angular distribution emitted by a single electron oscillating in these two undulators are then calculated. The radiation gain of a copropagating electromagnetic wave is calculated. The approximate analytic results for the trajectories, spontaneous radiation and gain are compared with 3-D simulation results. The characteristics of the plasma wave undulator are compared with the ac FEL undulator and linearly polarized magnetic undulator. 50 refs., 26 figs., 3 tabs.

Generation of radiation by intense plasma and electromagnetic undulators

International Nuclear Information System (INIS)

Joshi, C.

1991-10-01

We examine the characteristics of the classical radiation emission resulting from the interaction of a relativistic electron beam that propagates perpendicularly through a large amplitude relativistic plasma wave. Such a study is useful for evaluating the feasibility of using relativistic plasma waves as extremely short wavelength undulators for generating short wavelength radiation. The electron trajectories in a plasma wave undulator and in an ac FEL undulator are obtained using perturbation techniques. The spontaneous radiation frequency spectrum and angular distribution emitted by a single electron oscillating in these two undulators are then calculated. The radiation gain of a copropagating electromagnetic wave is calculated. The approximate analytic results for the trajectories, spontaneous radiation and gain are compared with 3-D simulation results. The characteristics of the plasma wave undulator are compared with the ac FEL undulator and linearly polarized magnetic undulator. 50 refs., 26 figs., 3 tabs

Errors in practical measurement in surveying, engineering, and technology

International Nuclear Information System (INIS)

Barry, B.A.; Morris, M.D.

1991-01-01

This book discusses statistical measurement, error theory, and statistical error analysis. The topics of the book include an introduction to measurement, measurement errors, the reliability of measurements, probability theory of errors, measures of reliability, reliability of repeated measurements, propagation of errors in computing, errors and weights, practical application of the theory of errors in measurement, two-dimensional errors and includes a bibliography. Appendices are included which address significant figures in measurement, basic concepts of probability and the normal probability curve, writing a sample specification for a procedure, classification, standards of accuracy, and general specifications of geodetic control surveys, the geoid, the frequency distribution curve and the computer and calculator solution of problems

Undulator radiation in a waveguide

Energy Technology Data Exchange (ETDEWEB)

Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

2007-03-15

We propose an analytical approach to characterize undulator radiation near resonance, when the presence of the vacuum-pipe considerably affects radiation properties. This is the case of the far-infrared undulator beamline at the Free-electron LASer (FEL) in Hamburg (FLASH), that will be capable of delivering pulses in the TeraHertz (THz) range. This undulator will allow pump-probe experiments where THz pulses are naturally synchronized to the VUV pulse from the FEL, as well as the development of novel electron-beam diagnostics techniques. Since the THz radiation diffraction-size exceeds the vacuum-chamber dimensions, characterization of infrared radiation must be performed accounting for the presence of a waveguide.We developed a theory of undulator radiation in a waveguide based on paraxial and resonance approximation. We solved the field equation with a tensor Green's function technique, and extracted figure of merits describing in a simple way the influence of the vacuum-pipe on the radiation pulse as a function of the problem parameters. Our theory, that makes consistent use of dimensionless analysis, allows treatment and physical understanding of many asymptotes of the parameter space, together with their region of applicability. (orig.)

Undulator radiation in a waveguide

International Nuclear Information System (INIS)

Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

2007-03-01

We propose an analytical approach to characterize undulator radiation near resonance, when the presence of the vacuum-pipe considerably affects radiation properties. This is the case of the far-infrared undulator beamline at the Free-electron LASer (FEL) in Hamburg (FLASH), that will be capable of delivering pulses in the TeraHertz (THz) range. This undulator will allow pump-probe experiments where THz pulses are naturally synchronized to the VUV pulse from the FEL, as well as the development of novel electron-beam diagnostics techniques. Since the THz radiation diffraction-size exceeds the vacuum-chamber dimensions, characterization of infrared radiation must be performed accounting for the presence of a waveguide.We developed a theory of undulator radiation in a waveguide based on paraxial and resonance approximation. We solved the field equation with a tensor Green's function technique, and extracted figure of merits describing in a simple way the influence of the vacuum-pipe on the radiation pulse as a function of the problem parameters. Our theory, that makes consistent use of dimensionless analysis, allows treatment and physical understanding of many asymptotes of the parameter space, together with their region of applicability. (orig.)

Gravity model improvement investigation. [improved gravity model for determination of ocean geoid

Science.gov (United States)

Siry, J. W.; Kahn, W. D.; Bryan, J. W.; Vonbun, F. F.

1973-01-01

This investigation was undertaken to improve the gravity model and hence the ocean geoid. A specific objective is the determination of the gravity field and geoid with a space resolution of approximately 5 deg and a height resolution of the order of five meters. The concept of the investigation is to utilize both GEOS-C altimeter and satellite-to-satellite tracking data to achieve the gravity model improvement. It is also planned to determine the geoid in selected regions with a space resolution of about a degree and a height resolution of the order of a meter or two. The short term objectives include the study of the gravity field in the GEOS-C calibration area outlined by Goddard, Bermuda, Antigua, and Cape Kennedy, and also in the eastern Pacific area which is viewed by ATS-F.

Reconciling Long-Wavelength Dynamic Topography, Geoid Anomalies and Mass Distribution on Earth

Science.gov (United States)

Hoggard, M.; Richards, F. D.; Ghelichkhan, S.; Austermann, J.; White, N.

2017-12-01

Since the first satellite observations in the late 1950s, we have known that that the Earth's non-hydrostatic geoid is dominated by spherical harmonic degree 2 (wavelengths of 16,000 km). Peak amplitudes are approximately ± 100 m, with highs centred on the Pacific Ocean and Africa, encircled by lows in the vicinity of the Pacific Ring of Fire and at the poles. Initial seismic tomography models revealed that the shear-wave velocity, and therefore presumably the density structure, of the lower mantle is also dominated by degree 2. Anti-correlation of slow, probably low density regions beneath geoid highs indicates that the mantle is affected by large-scale flow. Thus, buoyant features are rising and exert viscous normal stresses that act to deflect the surface and core-mantle boundary (CMB). Pioneering studies in the 1980s showed that a viscosity jump between the upper and lower mantle is required to reconcile these geoid and tomographically inferred density anomalies. These studies also predict 1-2 km of dynamic topography at the surface, dominated by degree 2. In contrast to this prediction, a global observational database of oceanic residual depth measurements indicates that degree 2 dynamic topography has peak amplitudes of only 500 m. Here, we attempt to reconcile observations of dynamic topography, geoid, gravity anomalies and CMB topography using instantaneous flow kernels. We exploit a density structure constructed from blended seismic tomography models, combining deep mantle imaging with higher resolution upper mantle features. Radial viscosity structure is discretised, and we invert for the best-fitting viscosity profile using a conjugate gradient search algorithm, subject to damping. Our results suggest that, due to strong sensitivity to radial viscosity structure, the Earth's geoid seems to be compatible with only ± 500 m of degree 2 dynamic topography.

Concept of quasi-periodic undulator - control of radiation spectrum

Energy Technology Data Exchange (ETDEWEB)

Sasaki, Shigemi [Japan Atomic Energy Research Institute, Ibaraki (Japan)

1995-02-01

A new type of undulator, the quasi-periodic undulator (QPU) is considered which generates the irrational harmonics in the radiation spectrum. This undulator consists of the arrays of magnet blocks aligned in a quasi-periodic order, and consequentially lead to a quasi-periodic motion of electron. A combination of the QPU and a conventional crystal/grating monochromator provides pure monochromatic photon beam for synchrotron radiation users because the irrational harmonics do not be diffracted in the same direction by a monochromator. The radiation power and width of each radiation peak emitted from this undulator are expected to be comparable with those of the conventional periodic undulator.

GNSS Wave Glider: First results from Loch Ness and demonstration of its suitability for determining the marine geoid

Science.gov (United States)

Penna, N. T.; Morales Maqueda, M.; Williams, S. D.; Foden, P.; Martin, I.; Pugh, J.

2013-12-01

We report on a first deployment of a GNSS Wave Glider designed for precise, unmanned, autonomous, mobile self-propelled sea level and sea state measurement in the open ocean. The Wave Glider, equipped with a dual frequency GPS+GLONASS receiver, was deployed in Loch Ness, Scotland, autonomously travelling 32 km in a north-easterly direction along the length of the loch in 26 hours, propelled by energy generated from waves of typical amplitude only 100-150 mm and frequency on the order 0.5-1 Hz. The Wave Glider GNSS data were analysed using a post-processed kinematic GPS+GLONASS precise point positioning (PPP) approach, which were quality controlled using double difference GPS kinematic processing with respect to onshore reference stations at either end of the loch. The PPP heights of the loch's surface revealed a clear geoid gradient of about 30 mm/km (i.e. just under 1 m over the whole length of the loch), very similar to both the EGM2008 and OSGM02 geoid models, demonstrating the potential use of a GNSS Wave Glider for marine geoid determination. After applying a low pass filter, the GNSS heights showed local deviations from both EGM2008 and OSGM02, potentially caused by omission errors or a lack of gravity data over Loch Ness. In addition to dual frequency GNSS data, the Wave Glider also recorded inclinometer data, bathymetry, and surface currents, which, in combination with tide gauge and wind data, were used to further control and interpret the GNSS time series.

Airborne gravimetry for geoid and GOCE

DEFF Research Database (Denmark)

Forsberg, R.; Olesen, A. V.; Nielsen, E.

2014-01-01

DTU-Space has since 1996 carried out large area airborne surveys over both polar, tropical and temperate regions, especially for geoid determination and global geopotential models. Recently we have started flying two gravimeters (LCR and Chekan-AM) side by side for increased reliability and redun......DTU-Space has since 1996 carried out large area airborne surveys over both polar, tropical and temperate regions, especially for geoid determination and global geopotential models. Recently we have started flying two gravimeters (LCR and Chekan-AM) side by side for increased reliability...... in Antarctica and Tanzania based on DTU-Space aerogravity and GOCE. In both cases the airborne data validate GOCE to very high degrees, and confirms the synergy of airborne gravity and GOCE. For Antarctica, the deep interior Antarctic survey (continued in 2013 from a remote field camp), shows...... that it is possible efficiently to cover even the most remote regions on the planet with good aerogravity. With the recent termination of the GOCE mission, it is therefore timely to initiate a coordinated, preferably international, airborne gravity effort to cover the polar gap south of 83° S; such a survey can...

What drives the Tibetan crust to the South East Asia? Role of upper mantle density discontinuities as inferred from the continental geoid anomalies

Science.gov (United States)

Rajesh, S.

2012-04-01

upper mantle beneath the Himalaya-Tibet has been studied by analyzing the geoid undulation data obtained from various satellite geodetic missions along with the recent and old (EGM2008 and EGM2006) Earth Gravity models. Results show that the net geoid anomaly varies from -65 m to -20 m, which signify a density stratified upper mantle beneath the Himalaya-Tibet and the same has been confirmed from the results of regional seismic tomography studies. The density anomaly distribution beneath Tibet from 163 km depth to its upper mantle thickness of 1063 km show a strong NW-SE elliptically oriented positive geoid anomalies of magnitude around 40 meter. Asymmetric density anomaly gradient have been observed along the Himalayan arc from west to east as well as across the arc from north to south. This caused differential gravitational potential gradient and hence an elliptical flow structure of the Tibetan continental mantle along the resultant NW-SE direction, which is in concurrence with the observed present day direction of the Tibetan crustal flow. Thus the geoid anomalies distributed at various depth ranges show how the gradient in the upper mantle gravitational potential energy, especially across the deformed discontinuity surface, is significant in determining the transfer of deviatoric stresses and providing traction to the flow of crustal layers of the Tibetan Plateau. This suggests the viscous flow model could be a preferable choice, which could better accommodate the dynamics of the upper mantle, in explaining the crustal extrusion processes of the Tibetan Plateau.

A conventional value for the geoid reference potential

Czech Academy of Sciences Publication Activity Database

Sánchez, L.; Čundrlík, R.; Dayoub, N.; Mikula, K.; Minarechová, Z.; Šíma, Zdislav; Vatrt, V.; Vojtíšková, M.

2016-01-01

Roč. 90, č. 9 (2016), s. 815-835 ISSN 0949-7714 Institutional support: RVO:67985815 Keywords : gobal W-0 value * W-0 best estimate * potential value of the geoid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.949, year: 2016

Superconducting Undulator with Variably Polarized Light

CERN Document Server

Hwang, Ching Shiang; Ching Fan, Tai; Li, W P; Lin, P H

2004-01-01

This study investigates planar in-vacuo superconducting undulators with periodic length of 5 cm (IVSU5) producing linearly and circularly polarized infrared rays or xrays source. The vertically wound racetrack coil is selected for the coil and pole fabrication of the IVSU5. When the up and down magnetic pole arrays with alternative directions rotated wires in the horizontal plane, a helical field radiates circularly polarized light in the electron storage ring, the free electron laser (FEL), and the energy recovery linac (ERL) facilities. Meanwhile, an un-rotated wire is constructed together with the rotated wire on the same undulator is used to switch the linear horizontal and vertical, the right- and left-circular polarization radiation. Given a periodic length of 5 cm and a gap of 23 mm, the maximum magnetic flux density in the helical undulator are Bz = 1.5 T and Bx = 0.5 T when the wires rotated by 20°. This article describes the main factors of the planar and helical undulator design for FEL and...

An electron undulating ring for VLSI lithography

International Nuclear Information System (INIS)

Tomimasu, T.; Mikado, T.; Noguchi, T.; Sugiyama, S.; Yamazaki, T.

1985-01-01

The development of the ETL storage ring ''TERAS'' as an undulating ring has been continued to achieve a wide area exposure of synchrotron radiation (SR) in VLSI lithography. Stable vertical and horizontal undulating motions of stored beams are demonstrated around a horizontal design orbit of TERAS, using two small steering magnets of which one is used for vertical undulating and another for horizontal one. Each steering magnet is inserted into one of the periodic configulation of guide field elements. As one of useful applications of undulaing electron beams, a vertically wide exposure of SR has been demonstrated in the SR lithography. The maximum vertical deviation from the design orbit nCcurs near the steering magnet. The maximum vertical tilt angle of the undulating beam near the nodes is about + or - 2mrad for a steering magnetic field of 50 gauss. Another proposal is for hith-intensity, uniform and wide exposure of SR from a wiggler installed in TERAS, using vertical and horizontal undulating motions of stored beams. A 1.4 m long permanent magnet wiggler has been installed for this purpose in this April

Design of a short-period superconducting undulator at KEK-PF

Energy Technology Data Exchange (ETDEWEB)

Ohmi, K.; Ikeda, N.; Ishii, S.

1998-06-01

A short-period undulator using a superconducting magnet is proposed. This undulator has been designed to install in the KEK-Photon Factory 2.5-GeV or 6.5-GeV storage ring. The idea of a staggered wiggler, developed in Stanford university, is used in this undulator. The target of the period and K value of the undulator are set to be 1 cm and 1, respectively. We can obtain monochromatic photons with an energy of {approx} 5keV or {approx} 40 keV by using the undulator. (author)

Undulator Hall Air Temperature Fault Scenarios

International Nuclear Information System (INIS)

Sevilla, J.

2010-01-01

Recent experience indicates that the LCLS undulator segments must not, at any time following tuning, be allowed to change temperature by more than about ±2.5 C or the magnetic center will irreversibly shift outside of acceptable tolerances. This vulnerability raises a concern that under fault conditions the ambient temperature in the Undulator Hall might go outside of the safe range and potentially could require removal and retuning of all the segments. In this note we estimate changes that can be expected in the Undulator Hall air temperature for three fault scenarios: (1) System-wide power failure; (2) Heating Ventilation and Air Conditioning (HVAC) system shutdown; and (3) HVAC system temperature regulation fault. We find that for either a system-wide power failure or an HVAC system shutdown (with the technical equipment left on), the short-term temperature changes of the air would be modest due to the ability of the walls and floor to act as a heat ballast. No action would be needed to protect the undulator system in the event of a system-wide power failure. Some action to adjust the heat balance, in the case of the HVAC power failure with the equipment left on, might be desirable but is not required. On the other hand, a temperature regulation failure of the HVAC system can quickly cause large excursions in air temperature and prompt action would be required to avoid damage to the undulator system.

An undulator with non-adiabatic tapering for the IFEL project

CERN Document Server

Varfolomeev, A A; Yarovoi, T V; Musumeci, P; Pellegrini, C; Rosenzweig, J

2002-01-01

We describe the design of a planar undulator with unusually strong tapering, for the inverse FEL experiment to be carried out in Neptune Lab. (Nucl. Instr. and Meth. A 410 (1998) 437) at UCLA. A powerful TW CO sub 2 laser will be used to accelerate electrons up to 50-60 MeV in 50 cm long undulator. A strong undulator tapering is needed because of the short Rayleigh length of the laser beam. Both the magnetic field and the undulator period are tapered to provide synchronicity of the laser beam interaction with a captured electron bunch along the whole undulator length. The most critical part of the undulator is the region near the laser focus. The main characteristics of the IFEL, such as the percentage of trapped electrons, energy of accelerated electrons and sensitivity to the laser focus transverse position, are given. The general principles of the design of this undulator construction can also be useful for high efficiency FEL amplifiers of intense laser modes.

Circular polarization with crossed-planar undulators in high-gain FELs

CERN Document Server

Kim, K J K J

2000-01-01

We propose a crossed undulator configuration for a high-gain free-electron laser to allow versatile polarization control. This configuration consists of a long (saturation length) planar undulator, a dispersive section, and a short (a few gain lengths) planar undulator oriented perpendicular to the first one. In the first undulator, a radiation component linearly polarized in the x-direction is amplified to saturation. In the second undulator, the x-polarized component propagates freely, while a new component, polarized in the y-direction, is generated and reaches saturation in a few gain lengths. By adjusting the strength of the dispersive section, the relative phase of two radiation components can be adjusted to obtain a suitable polarization for the total radiation field, including the circular polarization. The operating principle of the high-gain crossed undulator, which is quite different from that of the crossed undulator for spontaneous radiation, is illustrated in terms of 1-D FEL theory.

The AUSGeoid98 geoid model of Australia: data treatment, computations and comparisons with GPS-levelling data

DEFF Research Database (Denmark)

Featherstone, W.E.; Kirby, J.F.; Kearsley, A.H.W.

2001-01-01

The AUSGeoid98 gravimetric geoid model of Australia has been computed using data from the EGM96 global geopotential model, the 1996 release of the Australian gravity database, a nationwide digital elevation model, and satellite altimeter-derived marine gravity anomalies. The geoid heights are on ...

Enhancement of harmonic generation using a two section undulator

International Nuclear Information System (INIS)

Prazeres, R.; Glotin, F.; Jaroszynski, D.A.; Ortega, J.M.; Rippon, C.

1999-01-01

Enhancement of the 2nd and 3rd harmonic of the wavelength of a Free-Electron Laser (FEL) has been measured when a single electron beam is crossing a two-section undulator. To produce the harmonic radiation enhancement, the undulator is arranged so that the resonance wavelength of the 2nd undulator (downstream) matches a harmonic of the 1st undulator (upstream). Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction efficiency, through a hole in one of the cavity mirrors. We present measurements that show that the optical power at the 2nd and 3rd harmonic can be enhanced, by about one order of magnitude, in two configurations: when the resonance wavelength of the 2nd undulator matches the harmonic of 1st one (harmonic configuration), or when the gap of the 2nd undulator is slightly larger than first one (step-tapered configuration). We examine the dependence of the harmonic power on the gap of the 2nd undulator. This fundamental/harmonic mode of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture

Utilization of high resolution satellite geoid data for estimation of lithospheric thickness in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Majumdar, T.J.; Bhattacharyya, R.; Chatterjee, S.; Krishna, K.S.

been estimated using residual geoid data. In a similar fashion, the age offset from the age contours have been observed. (Figs. 5 a and b). Geoid models for ocean ridges and fracture zones If h(t) is the blope is the geoid as a function of seafloor... age, resulting from changes in seafloor depth and plate thickness due to cooling, then the quantity (∆h/age offset) estimated above is simply the derivative of h(t) with respect to age, where t is the mean age between two sides of a fracture8. From...

Undulators to FELs: Nanometers, Femtoseconds, Coherence and Applications

Energy Technology Data Exchange (ETDEWEB)

Attwood, David [University of California Berkeley

2011-11-30

For scientists in many fields, from material science to the life sciences and archeology, synchrotron radiation, and in particular undulator radiation, has provide an intense source of x-rays which are tunable to the absorption edges of particular elements of interest, often permitting studies at high spatial and spectral resolution. Now a close cousin to the undulator, the x-ray free electron laser (XFEL) has emerged with improved spatial coherence and, perhaps more importantly, femtosecond pulse durations which permit dynamical studies. In the future attosecond x-ray capabilities are anticipated. In this colloqium we will describe some state of the art undulator studies, how undulators work, the evolution to FELs, their pulse and coherence properties, and the types of experiments envisioned.

APPLE-II type quasi-periodic variably polarizing undulator at HiSOR

International Nuclear Information System (INIS)

Sasaki, Shigemi; Miyamoto, Atsushi; Goto, Kiminori

2012-01-01

A newly constructed quasi-periodic APPLE-II undulator was installed in the HiSOR ring at Hiroshima Synchrotron Radiation Center, Hiroshima University during the summer shutdown period in 2011. This 1.8 m-long undulator has a period length of 78 mm. In this article, the mechanism of magnetic field generation for various polarization modes of APPLE undulator, the principle of quasi-periodic undulator and the performance of HiSOR QP-APPLE-II undulator are described. (author)

Direct regional quasi-geoid determination using EGM2008 and DEM: A case study for Mainland China and its vicinity areas

Directory of Open Access Journals (Sweden)

Jin Li

2015-11-01

Full Text Available Earth's gravity model (EGM helps people better determine the figure of Earth, which is generally represented by a global geoid. For a considerable amount of practical applications, people use quasi-geoid to approximate the geoid, thus the quasi-geoid is also treated as an important height datum. In this study we revisit the method to directly determine regional quasi-geoid using EGM and digital elevation model (DEM, on the basis of Molodensky theory. According to the method we obtain a 5′ × 5′ quasi-geoid for Mainland China and its vicinity areas, based on the EGM2008 gravitational potential model and the Shuttle Radar Topography Mission (SRTM DEM model. By comparing height anomalies derived from EGM2008 with observations at 70 GPS/leveling points in areas including northwest, mid-west, mid-east and southeast of China, we find that the 5′ × 5′ EGM2008 quasi-geoid well fits the GPS/leveling results, with average deviations less than 10 cm for the selected areas in east China (with mainly plain topography and ∼20 cm for the selected areas in west China (highland or mountainous areas. We also discuss a few technical issues for directly determining height anomalies based on EGM and DEM, under the frame of Molodensky theory.

Assessment of Gravity Field and Steady State Ocean Circulation Explorer (GOCE) geoid model using GPS levelling over Sabah and Sarawak

Science.gov (United States)

Othman, A. H.; Omar, K. M.; Din, A. H. M.; Som, Z. A. M.; Yahaya, N. A. Z.; Pa'suya, M. F.

2016-06-01

The GOCE satellite mission has significantly contributed to various applications such as solid earth physics, oceanography and geodesy. Some substantial applications of geodesy are to improve the gravity field knowledge and the precise geoid modelling towards realising global height unification. This paper aims to evaluate GOCE geoid model based on the recent GOCE Global Geopotential Model (GGM), as well as EGM2008, using GPS levelling data over East Malaysia, i.e. Sabah and Sarawak. The satellite GGMs selected in this study are the GOCE GGM models which include GOCE04S, TIM_R5 and SPW_R4, and the EGM2008 model. To assess these models, the geoid heights from these GGMs are compared to the local geometric geoid height. The GGM geoid heights was derived using EGMLAB1 software and the geometric geoid height was computed by available GPS levelling information obtained from the Department Survey and Mapping Malaysia. Generally, the GOCE models performed better than EGM2008 over East Malaysia and the best fit GOCE model for this region is the TIM_R5 model. The TIM_R5 GOCE model demonstrated the lowest R.M.S. of ± 16.5 cm over Sarawak, comparatively. For further improvement, this model should be combined with the local gravity data for optimum geoid modelling over East Malaysia.

Control software of a variably polarizing undulator (APPLE type) for SX beamline in the SPring-8

Energy Technology Data Exchange (ETDEWEB)

Hiramatsu, Yoichi [Kansai Research Establishment, Japan Atomic Energy Research Institute, Mikazuki, Hyogo (Japan); Shimada, Taihei; Miyahara, Yoshikazu

1999-12-01

This paper describes the control software of a variably polarizing undulator (APPLE Type) that was installed at the SX beamline (cell number 23) in the SPring-8 storage ring in February, 1998. This undulator produces a polarized radiation in the energy range of soft X-ray by changing the gap distance between two pairs of permanent magnet arrays (gap movement). The main characteristic of the undulator is a capability to generate right and left circular polarization alternately at a period of 2 sec (0.5 Hz) by high speed phase-shifting (periodic phase movement). The developed software makes a fast correction of the closed orbit distortion (COD) of an electron beam by exciting steering magnets at a rate of time interval of 24 msec (42 Hz) during the movement of magnet arrays. Also, the software is capable to put these magnet arrays into a constant periodic phase movement with an error less than 0.1% for the period of 2 sec. The software was developed in accordance with the directions of SPring-8 standard for software development. (author)

Short-Period RF Undulator for a SASE Nanometer source

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2011-01-01

Analysis is described towards development of a RF undulator with a period < 1 cm, an undulator parameter K of the order of unity, and a gap greater than 2.25 mm. The application for the undulator is for a SASE source to produce 1 nm wavelength radiation using a low energy electron beam in the range 1-2 GeV. Particle orbit calculations in a conventional standing-wave resonator configuration show that the presence of a co-propagating component of RF field can cause deleterious motion for the undulating electrons that can seriously degrade their radiation spectrum. To obviate this problem, resonator designs were devised in which only the counter-propagating field components interact with the particles. Two resonator configurations with the same undulator parameter K = 0.4 have been devised and are described in this report.

U.S. Geoid Heights, Scientific Model (G96SSS)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the conterminous United States is the G96SSS model. The computation used about 1.8 million terrestrial and marine gravity data held in...

Magnetic Measurements of the Background Field in the Undulator Hall

International Nuclear Information System (INIS)

Fisher, Andrew

2010-01-01

The steel present in the construction of the undulator hall facility has the potential for changing the ambient fields present in the undulator hall. This note describes a measurement done to make a comparison between the fields in the hall and in the Magnetic Measurement Facility. In order for the undulators to have the proper tuning, the background magnetic field in the Undulator Hall should agree with the background field in the Magnetic Measurements Facility within .5 gauss. In order to verify that this was the case measurements were taken along the length of the undulator hall, and the point measurements were compared to the mean field which was measured on the MMF test bench.

Micropole undulator

Science.gov (United States)

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.

Undulator tunability and synchrotron ring-energy

International Nuclear Information System (INIS)

Viccaro, P.J.; Sheony, G.K.

1992-01-01

An undulator has two properties which make it an extremely attractive source of electromagnetic radiation. The first is that the radiation is concentrated in a number of narrow energy bands known as harmonics of the device. The second characteristic is that under favorable operating conditions, the energy of these harmonics can be shifted or open-quote tunedclose quotes over an energy interval which can be as large as two or three times the value of the lowest energy harmonic. Both the photon energy of an undulator as well as its tunability are determined by the period, λ, of the device, the magnetic gap, G (which is larger than the minimum aperture required for injection and operation of the storage ring) and the storage ring energy E R . Given the photon energy, E p , the above parameters ultimately define the limits of operation or tunability of the undulator. In general, the larger the tunability range, the more useful the device. Therefore, for a given required maximum photon energy, it is desirable to find the operating conditions and device parameters which result in the largest tunability interval possible. With this in mind, we have investigated the question of undulator tunability with emphasis on the role of the ring energy in order to find the smallest E R consistent with the desired tunability interval and photon energy. As a guideline, we have included a preliminary criteria, concerning the tunability requirements for the Advanced Photon Source (APS) to be built at Argonne. The analysis is aimed at X-ray undulator sources on the APS but is applicable to any storage ring

Simultaneous solution of the geoid and the surface density anomalies

Science.gov (United States)

Ardalan, A. A.; Safari, A.; Karimi, R.; AllahTavakoli, Y.

2012-04-01

The main application of the land gravity data in geodesy is "local geoid" or "local gravity field" modeling, whereas the same data could play a vital role for the anomalous mass-density modeling in geophysical explorations. In the realm of local geoid computations based on Geodetic Boundary Value Problems (GBVP), it is needed that the effect of the topographic (or residual terrain) masses be removed via application of the Newton integral in order to perform the downward continuation in a harmonic space. However, harmonization of the downward continuation domain may not be perfectly possible unless accurate information about the mass-density of the topographic masses be available. On the other hand, from the exploration point of view the unwanted topographical masses within the aforementioned procedure could be regarded as the signal. In order to overcome the effect of the remaining masses within the remove step of the GBVP, which cause uncertainties in mathematical modeling of the problem, here we are proposing a methodology for simultaneous solution of the geoid and residual surface density modeling In other words, a new mathematical model will be offered which both provides the needed harmonic space for downward continuation and at the same time accounts for the non-harmonic terms of gravitational field and makes use of it for residual mass density modeling within the topographic region. The presented new model enjoys from uniqueness of the solution, opposite to the inverse application of the Newton integral for mass density modeling which is non-unique, and only needs regularization to remove its instability problem. In this way, the solution of the model provides both the incremental harmonic gravitational potential on surface of the reference ellipsoid as the gravity field model and the lateral surface mass-density variations via the second derivatives of the non harmonic terms of gravitational field. As the case study and accuracy verification, the proposed

Coherent radiation in an undulator

International Nuclear Information System (INIS)

Chin, Yong Ho.

1990-12-01

This paper is concerned with the synchrotron radiation from an undulating electron beam in a rectangular waveguide. The analysis is based on the dyadic Green's function approach to solve Maxwell's equations in terms of the vector potential. It is shown analytically and numerically that the radiated energy spectrum may differ significantly from the free space results when the undulator length divided by the Lorentz factor of the electron beam is larger than the transverse size of the waveguide. Then, the appearance of the spectrum is changed into a small number of sharp peaks, each corresponding to an excited waveguide mode. The undulator radiation is identified with the wake field in beam instabilities. The concepts of wake function and impedance are introduced to formulate the present problem in the same manner as the beam instability problem, so that the accumulated techniques of the latter can be applied. It is shown that the obtained impedances satisfy the Panofsky-Wenzel theorem and other properties inevitable for wake fields. 4 refs., 2 figs

Electron Beam Alignment Strategy in the LCLS Undulators

International Nuclear Information System (INIS)

Nuhn, H

2007-01-01

The x-ray FEL process puts very tight tolerances on the straightness of the electron beam trajectory (2 (micro)m rms) through the LCLS undulator system. Tight but less stringent tolerances of 80 (micro)m rms vertical and 140 (micro)m rms horizontally are to be met for the placement of the individual undulator segments with respect to the beam axis. The tolerances for electron beam straightness can only be met through beam-based alignment (BBA) based on electron energy variations. Conventional alignment will set the start conditions for BBA. Precision-fiducialization of components mounted on remotely adjustable girders and the use of beam-finder wires (BFW) will satisfy placement tolerances. Girder movement due to ground motion and temperature changes will be monitored continuously by an alignment monitoring system (ADS) and remotely corrected. This stabilization of components as well as the monitoring and correction of the electron beam trajectory based on BPMs and correctors will increase the time between BBA applications. Undulator segments will be periodically removed from the undulator Hall and measured to monitor radiation damage and other effects that might degrade undulator tuning

Global detailed gravimetric geoid. [based on gravity model derived from satellite tracking and surface gravity data

Science.gov (United States)

Vincent, S.; Marsh, J. G.

1973-01-01

A global detailed gravimetric geoid has been computed by combining the Goddard Space Flight Center GEM-4 gravity model derived from satellite and surface gravity data and surface 1 deg-by-1 deg mean free air gravity anomaly data. The accuracy of the geoid is + or - 2 meters on continents, 5 to 7 meters in areas where surface gravity data are sparse, and 10 to 15 meters in areas where no surface gravity data are available. Comparisons have been made with the astrogeodetic data provided by Rice (United States), Bomford (Europe), and Mather (Australia). Comparisons have also been carried out with geoid heights derived from satellite solutions for geocentric station coordinates in North America, the Caribbean, Europe, and Australia.

Formation test of the plasma micro-undulator

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Noriyasu; Hashimoto, Kiyoshi; Aoki, Nobutada; Kimura, Hironobu; Konagai, Chikara; Nakagawa, Satoshi [Toshiba Corp., Yokohama, Kanagawa (Japan); Suzuki, Yasuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2000-03-01

An electrostatic plasma micro-undulator was demonstrated by utilizing methods of a laser interference and resonant photoionization. An ion-ripple can be formed across a relativistic electron beam injected into the micro-undulator. Thereby, synchrotron radiation light can be projected. Neodymium (Nd) target is ablated by a pulsed Nd-YAG laser beam, and the vapor is ionized by another laser beam with a wavelength tuned to a resonant ionization line of Nd atom. The laser beam for ionization is irradiated into Nd vapor using interference optics, and a micro-sized plasma-ripple corresponding to the interference fringes is shaped. In the experiment, the interference fringe with a periodic length from 10 to 300 {mu}m was formed, and the plasma-ripple was observed. The plasma density of order of 10{sup 13} cm{sup -3}, under the experimental condition, was not sufficient to obtain an effect expected as an undulator. However, optimization of a distance from the ablation spot to the laser plasma fringe and increase of laser power could achieve an undulator parameter K of more than 0.1. (author)

An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

DEFF Research Database (Denmark)

Skourup, Henriette; Farrell, Sinéad Louise; Hendricks, Stefan

2017-01-01

in a given model in the high frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean......State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors...... geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multi-sensor oceanographic time-series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04, DTU15...

DEVELOPMENT OF SHORT UNDULATORS FOR ELECTRON-BEAM-RADIATION INTERACTION STUDIES

Energy Technology Data Exchange (ETDEWEB)

Piot, P. [NICADD, DeKalb; Andorf, M. B. [NICADD, DeKalb; Fagerberg, G. [Northern Illinois U.; Figora, M. [Northern Illinois U.; Sturtz, A. [Northern Illinois U.

2016-10-19

Interaction of an electron beam with external field or its own radiation has widespread applications ranging from coherent-radiation generation, phase space cooling or formation of temporally-structured beams. An efficient coupling mechanism between an electron beam and radiation field relies on the use of a magnetic undulator. In this contribution we detail our plans to build short (11-period) undulators with 7-cm period refurbishing parts of the aladdin U3 undulator [1]. Possible use of these undulators at available test facilities to support experiments relevant to cooling techniques and radiation sources are outlined.

Helical undulator based on partial redistribution of uniform magnetic field

Science.gov (United States)

Balal, N.; Bandurkin, I. V.; Bratman, V. L.; Fedotov, A. E.

2017-12-01

A new type of helical undulator based on redistribution of magnetic field of a solenoid by ferromagnetic helix has been proposed and studied both in theory and experiment. Such undulators are very simple and efficient for promising sources of coherent spontaneous THz undulator radiation from dense electron bunches formed in laser-driven photo-injectors.

Up-grading a 4.7-cm-period plane electromagnetic undulator

International Nuclear Information System (INIS)

Bogachenkov, V.A.; Kondratyev, K.V.; Papadichev, V.A.

1999-01-01

Electromagnetic undulators have a number of advantages over permanent-magnet undulators. They are less expensive to fabricate and their field is easily regulated by changing the current, without requiring a complex and expensive precision system for changing the undulator gap. Their main weaknesses are that they require a large power supply and that the field is limited due to yoke saturation mainly because of large axial stray fluxes, particularly in simple constructions. Modernization of a 4.7-cm-period, 20-period long plane electromagnetic undulator of simple design is described. Samarium-cobalt permanent magnets were used to increase the field and decrease power consumption. They were placed between adjacent rings (with opposite sign of field) and while increasing the working field they decreased saturation of the iron yokes. Small lateral displacements of permanent magnets were used to equalize field amplitudes in half periods of the undulator with 0.1% accuracy. Matched input and output to and from the undulator, respectively, were formed by means of auxiliary permanent magnets and special magnetic screens

Investigation of the polarization state of dual APPLE-II undulators

International Nuclear Information System (INIS)

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

2016-01-01

Complete polarization analysis of the photon beam produced by a dual APPLE-II undulator configuration using a multilayer-based soft X-ray polarimeter is given. 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

Investigation of the polarization state of dual APPLE-II undulators

Energy Technology Data Exchange (ETDEWEB)

Hand, Matthew; Wang, Hongchang, E-mail: hongchang.wang@diamond.ac.uk; Dhesi, Sarnjeet S.; Sawhney, Kawal [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE (United Kingdom)

2016-01-01

Complete polarization analysis of the photon beam produced by a dual APPLE-II undulator configuration using a multilayer-based soft X-ray polarimeter is given. 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.

Correction of dynamic multipoles for APPLE-II undulator with flat wires

International Nuclear Information System (INIS)

Kikuchi, Y.; Hosaka, M.; Takashima, Y.; Yamamoto, N.; Adachi, M.; Zen, H.; Katoh, M.

2010-01-01

APPLE-II undulator can produce quasi-monochromatic light of different polarization though it is a relatively simple magnetic circuit. Therefore, it has been installed in many synchrotron radiation facilities and will be installed in Central Japan Synchrotron Radiation Research Facility under construction in Aichi prefecture. APPLE-II undulator also has been installed in UVSOR facility. When the undulator is operated in vertical polarization mode with narrower gap of 40 mm, the lifetime of electron beam through the storage ring significantly decreases.The reason is considered as dynamic multipole kicks in the undulator, which strongly depends on the undulator gap. Multi-wires, which are installed in the upper surface and the under surface of undulator beam duct, are candidate to compensate the multipole effects, because the multi-wires can generate arbitrary magnetic fields. This paper reports the result of numerical investigation on multipoles in the undulator by a three-dimensional magnetostatics computer code RADIA, the orbital calculation based on the numerical analysis and the preliminary experiment with flat wires. (author)

Helical undulator based on partial redistribution of uniform magnetic field

Directory of Open Access Journals (Sweden)

N. Balal

2017-12-01

Full Text Available A new type of helical undulator based on redistribution of magnetic field of a solenoid by ferromagnetic helix has been proposed and studied both in theory and experiment. Such undulators are very simple and efficient for promising sources of coherent spontaneous THz undulator radiation from dense electron bunches formed in laser-driven photo-injectors.

First test results for an adjustable phase undulator

International Nuclear Information System (INIS)

Carr, R.; Nuhn, H.D.; Corbett, J.

1992-01-01

An Adjustable Phase Undulator (APU) was installed and tested on the beamline 5 of the SPEAR storage ring. The APU has the same magnetic structure as a conventional adjustable gap undulator (AGU), but its magnetic field is varied by changing the longitudinal position between the rows of magnets, while keeping the gap between them fixed. The tests described here show that this undulator performs according to theoretical predictions and numerical models. The main reason to consider a phase adjustable design is the substantial reduction in size, complexity, and cost over comparable conventional designs. (author) 4 refs.; 3 figs

High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding

Digital Repository Service at National Institute of Oceanography (India)

Sreejith, K.M.; Rajesh, S.; Majumdar, T.J.; Rao, G.S.; Radhakrishna, M.; Krishna, K.S.; Rajawat, A.S.

') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites is presented. The geoid map of the Indian Ocean is dominated by a...

Interferometry using undulator sources

International Nuclear Information System (INIS)

Beguiristain, R.; Goldberg, K.A.; Tejnil, E.; Bokor, J.; Medecki, H.; Attwood, D.T.; Jackson, K.

1996-01-01

Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown. copyright 1996 American Institute of Physics

Field Optimization for short Period Undulators

CERN Document Server

Peiffer, P; Rossmanith, R; Schoerling, D

2011-01-01

Undulators dedicated to low energy electron beams, like Laser Wakefield Accelerators, require very short period lengths to achieve X-ray emission. However, at these short period length (LambdaU ~ 5 mm) it becomes difficult to reach magnetic field amplitudes that lead to a K parameter of >1, which is generally desired. Room temperature permanent magnets and even superconductive undulators using Nb-Ti as conductor material have proven insufficient to achieve the desired field amplitudes. The superconductor Nb$_{3}$Sn has the theoretical potential to achieve the desired fields. However, up to now it is limited by several technological challenges to much lower field values than theoretically predicted. An alternative idea for higher fields is to manufacture the poles of the undulator body from Holmium instead of iron or to use Nb-Ti wires with a higher superconductor/copper ratio. The advantages and challenges of the different options are compared in this contribution.

Canonical particle tracking in undulator fields

International Nuclear Information System (INIS)

Wuestefeld, G.; Bahrdt, J.

1991-01-01

A new algebraic mapping routine for particle tracking across wiggler and undulator fields in presented. It is based on a power series expansion of the generating function to guarantee fully canonical transformations. This method is 10 to 100 times faster than integration routines, applied in tracking codes like BETA or RACETRACK. The tracking method presented is not restricted to wigglers and undulators, it can be applied to other magnetic fields as well such as fringing fields of quadrupoles or dipoles if the suggested expansion converges

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

Science.gov (United States)

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.

Perspectives on micropole undulators in synchrotron radiation technology

International Nuclear Information System (INIS)

Tatchyn, R.; Csonka, P.; Toor, A.

1989-01-01

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

Perspectives on micropole undulators in synchrotron radiation technology

Science.gov (United States)

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.

Ocean tides and quasi-stationary departures from the marine geoid investigation

Science.gov (United States)

Siry, J. W.; Kahn, W. D.; Bryan, J. W.; Vonbun, F. O.

1973-01-01

The detection of tides and/or currents through the analysis of data generated in connection with the Ocean Geoid Determination Investigation is presented. A discussion of the detailed objectives and approach are included.

Performance of a hard x-ray undulator at CHESS

International Nuclear Information System (INIS)

Bilderback, D.H.; Batterman, B.W.; Bedzyk, M.J.; Finkelstein, K.; Henderson, C.; Merlini, A.; Schildkamp, W.; Shen, Q.; White, J.; Blum, E.B.; Viccaro, P.J.; Mills, D.M.; Kim, S.; Shenoy, G.K.; Robinson, K.E.; James, F.E.; Slater, J.M.

1989-01-01

A 3.3-cm period Nd-Fe-B hybrid undulator has been designed and successfully operated in the Cornell Electron Storage Ring (CESR). This 2-m-long, 123-pole insertion device is a prototype of one of the undulators planned for the Advanced Photon Source. In dedicated operation, the undulator produced the expected brightness at 5.437 GeV with the fundamental x-ray energy ranging from 4.3 to 7.9 keV corresponding to a change in gap from 1.5 to 2.8 cm

Magnetic performance of DEVU25.20h undulator at IDDL, DAVV,India

Science.gov (United States)

Mishra, G.; Gehlot, Mona; Sharma, Geetanjali; Khullar, Roma

2016-10-01

In this paper, we describe the design development and magnetic performance of a prototype DEVU25.20h, variable gap hybrid undulator at IDD laboratory, DAVV, Indore, India. The undulator is NdFeB based hybrid undulator with twenty five period and 20 mm each period length. Low cost M35 grade cobalt steel is used as the pole material of the undulator. The abc coefficients of the new pole material is prescribed and the measured performance and characteristics of the undulator is evaluated using RADIA. The detailed design parameters and performance indicators are summarized in Table 1 and Table 2 respectively.

Phasing multi-segment undulators

International Nuclear Information System (INIS)

Chavanne, J.; Elleaume, P.; Vaerenbergh, P. Van

1996-01-01

An important issue in the manufacture of multi-segment undulators as a source of synchrotron radiation or as a free-electron laser (FEL) is the phasing between successive segments. The state of the art is briefly reviewed, after which a novel pure permanent magnet phasing section that is passive and does not require any current is presented. The phasing section allows the introduction of a 6 mm longitudinal gap between each segment, resulting in complete mechanical independence and reduced magnetic interaction between segments. The tolerance of the longitudinal positioning of one segment with respect to the next is found to be 2.8 times lower than that of conventional phasing. The spectrum at all gaps and useful harmonics is almost unchanged when compared with a single-segment undulator of the same total length. (au) 3 refs

Up-grading a 4.7-cm-period plane electromagnetic undulator

CERN Document Server

Bogachenkov, V A; Papadichev, V A

1999-01-01

Electromagnetic undulators have a number of advantages over permanent-magnet undulators. They are less expensive to fabricate and their field is easily regulated by changing the current, without requiring a complex and expensive precision system for changing the undulator gap. Their main weaknesses are that they require a large power supply and that the field is limited due to yoke saturation mainly because of large axial stray fluxes, particularly in simple constructions. Modernization of a 4.7-cm-period, 20-period long plane electromagnetic undulator of simple design is described. Samarium-cobalt permanent magnets were used to increase the field and decrease power consumption. They were placed between adjacent rings (with opposite sign of field) and while increasing the working field they decreased saturation of the iron yokes. Small lateral displacements of permanent magnets were used to equalize field amplitudes in half periods of the undulator with 0.1% accuracy. Matched input and output to and from the ...

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

Energy Technology Data Exchange (ETDEWEB)

Kitegi, C., E-mail: ckitegi@bnl.gov; Chubar, O.; Eng, C. [Energy Sciences Directorates, Brookhaven National Laboratory, Upton NY1 1973 (United States)

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. We 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.

A superconducting short period undulator for a harmonic generation FEL experiment

International Nuclear Information System (INIS)

Ingold, G.; Solomon, L.; Ben-Zvi, I.; Krinsky, S.; Li, D.; Lynch, D.; Sheehan, J.; Woodle, M.; Qiu, X.Z.; Yu, L.H.

1993-01-01

A three stage superconducting (SC) undulator for a high gain harmonic generation (HGE) FEL experiment in the infrared is under construction at the NSLS in collaboration with Grumman Corporation. A novel undulator technology suitable for short period (6-40mm) undulators will be employed for all three stages, the modulator, the dispersive section and the radiator. The undulator triples the frequency of a 10.4μm CO 2 seed laser. So far a 27 period (one third of the final radiator) prototype radiator has been designed, built and tested

Improved representations of the Mediterranean Geoid within the GEOMED 2 project. Contributions of local gravity, GOCE and Cryosat2 data

DEFF Research Database (Denmark)

Barzaghi, Riccardo; Vergos, George S.; Albertella, Alberta

The Mediterranean Sea has always been a lab for geosciences, given its geodynamic peculiarities, the large short-scale variations of the gravity field and the complex circulation. Within the GEOMED 2 project, new improved representations of the Mediterranean marine geoid have been deemed...... of a Mediterranean-wide gravity database. The data employed within GEOMED 2 for the determination of the marine geoid are land and marine gravity data, GOCE/GRACE based Global Geopotential Models and a combination of MISTRAL and SRTM/bathymetry terrain models. The processing methodology will be based on the well......)-based techniques have provided the geoid estimation in the frequency domain. In this work, the pre-processing steps consisting in merging and validating all the available gravity observations for the wider Mediterranean are presented and discussed. Furthermore, the latest basin-wide geoid models are estimated from...

Undulator-Based Production of Polarized Photons

International Nuclear Information System (INIS)

McDonald, Kirk

2008-01-01

'Project Title: Undulator-Based Production of Polarized Photons' DOE Contract Number: FG02-04ER41355 Principal Investigator: Prof. Kirk McDonald Period of Performance: 09/10/2004 thru 08/31/2006 This award was to fund Princeton's activity on SLAC experiment E166, 'Undulator-Based Production of Polarized Positrons' which was performed at SLAC during June and September 2005. Princeton U. fabricated a magnetic spectrometer for this experiment, and participated in the commissioning, operation, and analysis of the experiment, for which Prof. McDonald was a co-spokesperson. The experiment demonstrated that an intense positron beam with 80% longitudinal polarization could be generated by conversion of MeVenergy circularly polarized photons in a thin target, which photons were generated by passage of high-energy electrons through a helical undulator. This technique has since been adopted as the baseline for the polarized positron source of the proposed International Linear Collider. Results of the experiment have been published in Physical Review Letters, vol 100, p 210801 (2008) (see attached .pdf file), and a longer paper is in preparation.

Evaluation of the geopotential value W0LVD of China

Directory of Open Access Journals (Sweden)

Lin He

2017-11-01

Full Text Available Estimation of the zero-height geopotential value W0LVD for the CVD (China Vertical Datum plays a fundamental role in the connection of traditional height reference systems into a global height system. Estimation the W0LVD of China is based on the computation of the mean geopotential offset between the value W0 = 62636856.0 m2s−2, selected as reference in this study, and the unknown geopotential value W0LVD. This estimation is based on the combination of ellipsoidal heights, levelled heights (referring to the CVD, and some physical parameters, such as geopotential values, gravity values, and geoid undulations. The geoid undulations derived from the GGM (Global Geopotential Models. This combination is performed through three approaches: The first one is based on the theory of Molodensky, and the second one compares levelled heights and geopotential values derived from the GGMs, while the third one analyses the differences between GPS/Levelling and GGMs geoid undulations. The approaches are evaluated at 65 benchmarks (BMs covered around Qingdao where the tide gauge is used to observe the local mean sea level of China. The results from three approaches are very similar. Furthermore, the W0LVD determined for the China local vertical datum was 62636852.9462 m2s−2, indicates a bias of about 3.0538 m2/s−2 compared to the conventional value of 62636856.0 m2s−2.

1-deg x 1-deg Terrestrial Mean Free-Air Anomalies

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The 1x1 degree Terrestrial Mean Free-Air Gravity Anomaly and Geoid Undulations Data Base was compiled and developed by the Ohio State University. This data base was...

30-min x 30-min Terrestrial Mean Free-Air Anomalies

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The 30-min x 30-min Terrestrial Mean Free-Air Gravity Anomaly and Geoid Undulations Data Base was compiled and developed by the Ohio State University. This data base...

Variable-Period Undulators For Synchrotron Radiation

Science.gov (United States)

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.

Variable-Period Undulators for Synchrotron Radiation

Energy Technology Data Exchange (ETDEWEB)

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.

Photon energy tunability of advanced photon source undulators

International Nuclear Information System (INIS)

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

1987-08-01

At a fixed storage ring energy, the energy of the harmonics of an undulator can be shifted or ''tuned'' by changing the magnet gap of the device. The possible photon energy interval spanned in this way depends on the undulator period, minimum closed gap, minimum acceptable photon intensity and storage ring energy. The minimum magnet gap depends directly on the stay clear particle beam aperture required for storage ring operation. The tunability of undulators planned for the Advanced Photon Source with first harmonic photon energies in the range of 5 to 20 keV are discussed. The results of an analysis used to optimize the APS ring energy is presented and tunability contours and intensity parameters are presented for two typical classes of devices

Magnetic measurement, sorting optimization and adjustment of SDUV-FEL hybrid undulator

International Nuclear Information System (INIS)

Wang Tao; Jia Qika

2007-01-01

Construction of an undulator includes magnet block measurement, sorting, field measurement and adjustment. Optimizing SDUV-FEL undulator by simulated annealing algorithm using measurement results of the magnet blocks by Helmholtz coil before installing undulator magnets, the cost function can be reduced by three orders of magnitude. The practical parameters of one segment meet the design specifications after adjusting the magnetic field. (authors)

Tapering of the CHESS-APS undulator: Results and modelling

International Nuclear Information System (INIS)

Lai, B.; Viccaro, P.J.; Dejus, R.; Gluskin, E.; Yun, W.B.; McNulty, I.; Henderson, C.; White, J.; Shen, Q.; Finkelstein, K.

1992-01-01

When the magnetic gap of an undulator is tapered along the beam direction, the slowly varying peak field B o introduces a spread in the value of the deflection parameter K. The result is a broad energy-band undulator that still maintains high degree of spatial collimation. These properties are very useful for EXAFS and energy dispersive techniques. We have characterized the CHESS-APS undulator (1 υ = 3.3cm) at one tapered configuration (10% change of the magnetic gap from one end of the undulator to the other). Spatial distribution and energy spectra of the first three harmonics through a pinhole were measured. The on-axis first harmonic width increased from 0.27 keV to 0.61 keV (FWHM) at the central energy of E 1 = 6.6 keV (K average = 0.69). Broadening in the angular distribution due to tapering was minimal. These results will be compared with computer modelling which simulates the actual electron trajectory in the tapered case

The LCLS Undulator Beam Loss Monitor Readout System

Energy Technology Data Exchange (ETDEWEB)

Dusatko, John; Browne, M.; Fisher, A.S.; Kotturi, D.; Norum, S.; Olsen, J.; /SLAC

2012-07-23

The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault signal, the LCLS Machine Protection System takes appropriate action by either halting or rate limiting the beam. The BLM detector consists of a PMT coupled to a Cherenkov radiator located near the upstream end of each undulator segment. There are 33 BLMs in the system, one per segment. The detectors are read out by a dedicated system that is integrated directly into the LCLS MPS. The BLM readout system provides monitoring of radiation levels, computation of integrated doses, detection of radiation excursions beyond set thresholds, fault reporting and control of BLM system functions. This paper describes the design, construction and operational performance of the BLM readout system.

Mechanical design and fabrication of pure-permanent magnet undulator

International Nuclear Information System (INIS)

Chouksey, Sanjay; Vinit Kumar; Abhay Kumar; Krishnagopal, Srinivas

2003-01-01

A 50 mm period, 2.5 m long (50 periods), pure permanent magnet, variable gap undulator using NdFeB magnets is being built in two sections, each 1.25 m long. We present details of the mechanical design, fabrication experience, assembly and inspection of the undulator. (author)

Coherent harmonic production using a two-section undulator FEL

Energy Technology Data Exchange (ETDEWEB)

Jaroszynski, D.A. [Commissariat a l`Energie, Bruyeres-le-Chatel (France); Prazeres, R.; Glotin, F. [Centre Universitaire Paris-Sud (France)] [and others

1995-12-31

We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonic can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.

GRAVTool, Advances on the Package to Compute Geoid Model path by the Remove-Compute-Restore Technique, Following Helmert's Condensation Method

Science.gov (United States)

Marotta, G. S.

2017-12-01

Currently, there are several methods to determine geoid models. They can be based on terrestrial gravity data, geopotential coefficients, astrogeodetic data or a combination of them. Among the techniques to compute a precise geoid model, the Remove Compute Restore (RCR) has been widely applied. It considers short, medium and long wavelengths derived from altitude data provided by Digital Terrain Models (DTM), terrestrial gravity data and Global Geopotential Model (GGM), respectively. In order to apply this technique, it is necessary to create procedures that compute gravity anomalies and geoid models, by the integration of different wavelengths, and adjust these models to one local vertical datum. This research presents the advances on the package called GRAVTool to compute geoid models path by the RCR, following Helmert's condensation method, and its application in a study area. The studied area comprehends the federal district of Brazil, with 6000 km², wavy relief, heights varying from 600 m to 1340 m, located between the coordinates 48.25ºW, 15.45ºS and 47.33ºW, 16.06ºS. The results of the numerical example on the studied area show a geoid model computed by the GRAVTool package, after analysis of the density, DTM and GGM values, more adequate to the reference values used on the study area. The accuracy of the computed model (σ = ± 0.058 m, RMS = 0.067 m, maximum = 0.124 m and minimum = -0.155 m), using density value of 2.702 g/cm³ ±0.024 g/cm³, DTM SRTM Void Filled 3 arc-second and GGM EIGEN-6C4 up to degree and order 250, matches the uncertainty (σ =± 0.073) of 26 points randomly spaced where the geoid was computed by geometrical leveling technique supported by positioning GNSS. The results were also better than those achieved by Brazilian official regional geoid model (σ = ± 0.076 m, RMS = 0.098 m, maximum = 0.320 m and minimum = -0.061 m).

Undulators and free-electron lasers

CERN Document Server

Luchini, P

1990-01-01

This book is a reference text for all those working in free-electron laser research as well as being a learning aid for physicists and graduate students who wish an introduction to this field. Only a basic understanding of relativistic mechanics and electromagnetism is presupposed. After an overview of early developments and general principles of operation, the different models that can be used to describe free-electron lasers are presented, organized according to their range of applicability. The relevent conceptual and mathematical constructs are built up from first principles with attention to obtaining the practically important results in a simple but rigorous way. Interaction of the undulator with the driving electron accelerator and the laser cavity and design of undulator magnets are treated and an overview is given of some typical experiments.

A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator

CERN Document Server

Pellegrini, C; Travish, G

2005-01-01

We describe a proposed high-gain FEL using an X-band microwave undulator and operating at a wavelength of about 0.5 μm. The FEL electron beam energy is 65 MeV. The beam is produced by the NLCTA X-band linac at SLAC, using an S-band high-brightness photoinjector. The undulator consists of a circular waveguide with an rf wave counter-propagating with respect to the electron beam. The undulator is powered with two high-power X-band klystrons and a dual-moded pulse compressor recently developed at SLAC. This system is capable of delivering flat-top rf pulses of up to 400 ns and a few hundred megawatts. The equivalent undulator period is 1.4 cm, the radius of the circular pipe is 1 cm, and the undulator parameter is about 0.4 for a helical undulator configuration, obtained using two cross-polarized TE modes, or larger for a planar configuration, using one rf polarization. The undulator is about four meters long. The FEL will reach saturation within this distance when operated in a SASE mode. We describe t...

Undulator physics and coherent harmonic generation at the MAX-lab electron storage ring

International Nuclear Information System (INIS)

Werin, Sverker.

1991-01-01

This work presents the undulator and harmonic generation project at the electron storage ring MAX-lab at University of Lund. The theory of undulator radiation, laser coherent harmonic generation, optical klystron amplifiers and FELs is treated in one uniform way, with complete solutions of the necessary equations. The permanent magnet undulator is described in some detail, along with the installation of the undulator in the storage ring. Details regarding the emitted radiation, the electron beam path in the undulator and other results are analysed. Finally harmonic generation using a Nd:YAG laser and the creation of coherent photons at the third harmonic (355 nm) is described. (author)

Production of linear polarization by segmentation of helical undulator

International Nuclear Information System (INIS)

Tanaka, T.; Kitamura, H.

2002-01-01

A simple scheme to obtain linearly polarized radiation (LPR) with a segmented undulator is proposed. The undulator is composed of several segments each of which forms a helical undulator and has helicity opposite to those of adjacent segments. Due to coherent sum of radiation, the circularly polarized component is canceled out resulting in production of LPR without any higher harmonics. The radiation from the proposed device is investigated analytically, which shows that a high degree of linear polarization is obtained in spite of a finite beam emittance and angular acceptance of optics, if a sufficiently large number of segments and an adequate photon energy are chosen. Results of calculation to investigate practical performances of the proposed device are presented

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

Science.gov (United States)

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.

Undulator sources at a 8 GeV storage ring

International Nuclear Information System (INIS)

Harami, Taikan.

1989-06-01

The use of undulators plays an important role as a high brilliance sources of synchrotron photon at a facility having an electron (or positron) storage ring. This paper describes the characteristics, tunability from gap variation and brilliance of synchrotron photon from undulators at a 8 GeV storage ring. The numerical studies show the following results. (1) Undulators for a 8 GeV storage ring can cover the first harmonic photon energy range from about 0.3 to 30 keV and the third harmonic photon from 0.85 to 70 keV. (2) The brilliance of undulator can be expected to be the order of 10 21 photons/(sec mm 2 mrad 2 0.1% band width mA), without size and angular spread in the electron beam (diffraction limit). (3) The peak brilliance has a broad maximum as a function of β function of the lattice and is shown to be practically independent on the β function. The peak brilliance is calculated to be the order of 10 16 photons/(sec mm 2 mrad 2 0.1% band width mA) at the electron beam emittance of 5 x 10 -9 m·rad (undulator length 2 m). (4) The nuclei of 57 Fe, 119 Sn and 238 U are expected to be the candidates for the Moessbauer scattering experiment using synchrotron photon from a 8 GeV storage ring. (author)

Application of GPS in a high precision engineering survey network

International Nuclear Information System (INIS)

Ruland, R.; Leick, A.

1985-04-01

A GPS satellite survey was carried out with the Macrometer to support construction at the Stanford Linear Accelerator Center (SLAC). The network consists of 16 stations of which 9 stations were part of the Macrometer network. The horizontal and vertical accuracy of the GPS survey is estimated to be 1 to 2 mm and 2 to 3 mm respectively. The horizontal accuracy of the terrestrial survey, consisting of angles and distances, equals that of the GPS survey only in the ''loop'' portion of the network. All stations are part of a precise level network. The ellipsoidal heights obtained from the GPS survey and the orthometric heights of the level network are used to compute geoid undulations. A geoid profile along the linac was computed by the National Geodetic Survey in 1963. This profile agreed with the observed geoid within the standard deviation of the GPS survey. Angles and distances were adjusted together (TERRA), and all terrestrial observations were combined with the GPS vector observations in a combination adjustment (COMB). A comparison of COMB and TERRA revealed systematic errors in the terrestrial solution. A scale factor of 1.5 ppM +- .8 ppM was estimated. This value is of the same magnitude as the over-all horizontal accuracy of both networks. 10 refs., 3 figs., 5 tabs

An ocean modelling and assimilation guide to using GOCE geoid products

DEFF Research Database (Denmark)

Haines, K.; Johannessen, J. A.; Knudsen, Per

2011-01-01

We review the procedures and challenges that must be considered when using geoid data derived from the Gravity and steady-state Ocean Circulation Explorer (GOCE) mission in order to constrain the circulation and water mass representation in an ocean general circulation model. It covers the combin...

Undulator-based production of polarized positrons

Energy Technology Data Exchange (ETDEWEB)

Alexander, G. [Tel-Aviv Univ. (Israel); Barley, J. [Cornell Univ., Ithaca, NY (United States); Batygin, Y. [SLAC, Menlo Park, CA (US)] (and others)

2009-05-15

Full exploitation of the physics potential of a future International Linear Collider will require the use of polarized electron and positron beams. Experiment E166 at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which an electron beam passes through a helical undulator to generate photons (whose first-harmonic spectrum extended to 7.9 MeV) with circular polarization, which are then converted in a thin target to generate longitudinally polarized positrons and electrons. The experiment was carried out with a one-meter-long, 400-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) operated at 46.6 GeV. Measurements of the positron polarization have been performed at five positron energies from 4.5 to 7.5 MeV. In addition, the electron polarization has been determined at 6.7MeV, and the effect of operating the undulator with a ferrofluid was also investigated. To compare the measurements with expectations, detailed simulations were made with an upgraded version of GEANT4 that includes the dominant polarization-dependent interactions of electrons, positrons, and photons with matter. The measurements agree with calculations, corresponding to 80% polarization for positrons near 6 MeV and 90% for electrons near 7 MeV. (orig.)

Definition of Physical Height Systems for Telluric Planets and Moons

Science.gov (United States)

Tenzer, Robert; Foroughi, Ismael; Sjöberg, Lars E.; Bagherbandi, Mohammad; Hirt, Christian; Pitoňák, Martin

2018-01-01

Regio. The largest geoid undulations between - 747 and 1685 m were found on Mars, with the extreme positive geoidal heights under Olympus Mons in Tharsis region. Large variations in the geoidal geometry are also confirmed on the Moon, with the geoidal heights ranging from - 298 to 461 m. For comparison, the terrestrial geoid undulations are mostly within ± 100 m. We also demonstrate that a commonly used method for computing the geoidal heights that disregards the differences between the gravity field outside and inside topographic masses yields relatively large errors. According to our estimates, these errors are - 0.3/+ 3.4 m for Mercury, 0.0/+ 13.3 m for Venus, - 1.4/+ 125.6 m for Mars, and - 5.6/+ 45.2 m for the Moon.

A variable radius mirror for imaging the exit slit of an SGM undulator beamline at the ALS

International Nuclear Information System (INIS)

Warwick, T.; Howells, M.

1994-01-01

Bendable metal mirrors have been implemented in two SGM undulator beamlines at the ALS. A piezo-electric actuator is employed to deform the mirror to image the SGM exit slit which moves longitudinally in the beamline as the grating rotates. The design and performance of these mirrors is discussed. Computed deformations and slope errors are compared to those found during optical metrology. The soft x-ray spot size produced at the experiment is shown

A variable radius mirror for imaging the exit slit of an SGM undulator beamline at the ALS

International Nuclear Information System (INIS)

Warwick, T.; Howells, M.

1994-07-01

Bendable metal mirrors have been implemented in two SGM undulator beamlines at the ALS. A piezo-electric actuator is employed to deform the mirror to image the SGM exit slit which moves longitudinally in the beamline as the grating rotates. The design and performance of these mirrors is discussed. Computed deformations and slope errors are compared to those found during optical metrology. The soft x-ray spot size produced at the experiment is shown

Intensity interferometry at the X13A undulator beamline

International Nuclear Information System (INIS)

Gluskin, E.; McNulty, I.; Yang, L.; Randall, K.J.; Johnson, E.D.

1993-01-01

We are constructing a soft x-ray intensity interferometer and an undulator based beamline to demonstrate intensity interferometry in the x-ray region. The 10-period soft x-ray undulator at the NSLS provides the necessary coherent flux; the X13A beamline is designed to preserve the spatial coherence of the bright x-ray beam and provide sufficient temporal coherence using a horizontally deflecting spherical grating monochromator. Using the interferometer, which consists of an array of small slits, a wedge-shaped beamsplitter and two fast microchannel plate detectors, we expect to measure the spatial coherence of the undulator beam and therefore the size of the source in the vertical plane. Details of the bean-dine design and the interferometer experiment are discussed

On the inversion of geodetic integrals defined over the sphere using 1-D FFT

Science.gov (United States)

García, R. V.; Alejo, C. A.

2005-08-01

An iterative method is presented which performs inversion of integrals defined over the sphere. The method is based on one-dimensional fast Fourier transform (1-D FFT) inversion and is implemented with the projected Landweber technique, which is used to solve constrained least-squares problems reducing the associated 1-D cyclic-convolution error. The results obtained are as precise as the direct matrix inversion approach, but with better computational efficiency. A case study uses the inversion of Hotine’s integral to obtain gravity disturbances from geoid undulations. Numerical convergence is also analyzed and comparisons with respect to the direct matrix inversion method using conjugate gradient (CG) iteration are presented. Like the CG method, the number of iterations needed to get the optimum (i.e., small) error decreases as the measurement noise increases. Nevertheless, for discrete data given over a whole parallel band, the method can be applied directly without implementing the projected Landweber method, since no cyclic convolution error exists.

[Preclinical study of immunocorrection action of the sum of active substances of Coluria geoides (Pall.) Ledeb. (Rosaceae)].

Science.gov (United States)

Dutova, S V; Karpova, M R; Myadelets, M A; Myasnaya, N V; Sherstoboev, E Yu

2015-01-01

A preclinical study of the immunocorrection action of the sum of active substances isolated from ethereal-oil plants Coluria geoides (Pall.) Ledeb. (Rosaceae family) with respect to experimental immunodeficiency showed that preparations relieve symptoms of immunodeficiency caused by the administration of cyclophosphan: suppressed synthesis of anti-erythrocyte antibodies (agglutinine) and proliferative processes in the spleen. Under the influence of C. geoides preparations, the absolute numbers of cariocytes and antibody forming cells in spleen significantly increased (compared to the group of animals with experimental immunodeficiency) and in some cases reached the background level. The drugs studied produced a more pronounced stimulating effect on the synthesis of specific immunoglobulins and proliferation of antibody forming cells of spleen as compared to the effect of Echinacea tincture. Preparation C-2 (extract from underground organs and grass of C. geoides obtained by percolation method with 70% ethanol) is most promising for in-depth research and the development of new effective drugs with immunocorrecting properties.

Compact Undulator for the Cornell High Energy Synchrotron Source: Design and Beam Test Results

Science.gov (United States)

Temnykh, A.; Dale, D.; Fontes, E.; Li, Y.; Lyndaker, A.; Revesz, P.; Rice, D.; Woll, A.

2013-03-01

We developed, built and beam tested a novel, compact, in-vacuum undulator magnet based on an adjustable phase (AP) scheme. The undulator is 1 m long with a 5mm gap. It has a pure permanent magnet structure with 24.4mm period and 1.1 Tesla maximum peak field. The device consists of two planar magnet arrays mounted on rails inside of a rectangular box-like frame with 156 mm × 146 mm dimensions. The undulator magnet is enclosed in a 273 mm (10.75") diameter cylindrical vacuum vessel with a driver mechanism placed outside. In May 2012 the CHESS Compact Undulator (CCU) was installed in Cornell Electron Storage Ring and beam tested. During four weeks of dedicated run we evaluated undulator radiation properties as well as magnetic, mechanical and vacuum properties of the undulator magnet. We also studied the effect of the CCU on storage ring beam. The spectral characteristics and intensity of radiation were found to be in very good agreement with expected. The magnet demonstrated reproducibility of undulator parameter K at 1.4 × 10-4 level. It was also found that the undulator K. parameter change does not affect electron beam orbit and betatron tunes.

An initial investigation of the GOCE error variance-covariance matrices in the context of the GOCE user toolbox project

DEFF Research Database (Denmark)

Bingham, Rory J.; Tscherning, Christian; Knudsen, Per

2011-01-01

The availability of the full error variance-covariance matrices for the GOCE gravity field models is an important feature of the GOCE mission. Potentially, it will allow users to evaluate the accuracy of a geoid or mean dynamic topography (MDT) derived from the gravity field model at any particul...

Development of a cryogenic permanent magnet undulator at the ESRF

International Nuclear Information System (INIS)

Kitegi, Ch.

2008-12-01

In 2004, at SPring-8, Toru Hara proposed a new concept of undulator with a short period and a high field: the Cryogenic Permanent Magnet Undulator (CPMU). The purpose of this concept is to cool Nd 2 Fe 14 B magnets at 150 K. This cooling allows magnets which have a higher remanence to be used, up to 40% higher than that of the magnets traditionally used in undulators. In order to assess the technological possibility of producing such undulator, a 2 m long undulator with a 18 mm period has been proposed at the ESRF. This piece of work presents the design and the construction of this CPMU at the ESRF. First a magnetic model of the CPMU is introduced; it is based on measurements of the magnetization curve at cryogenic temperature performed at the Louis Neel Laboratory. This model forecasts an increase of the peak field of 8% and of the field integral of 0.2 Gm at around 150 K. A unique magnetic measurement bench has been developed at the ESRF. This bench allows both the in vacuum local field and field integral to be measured. Its design and construction are presented. Finally we have reviewed the measurements at room and cryogenic temperature. These measurements are in agreement with the magnetic model. (author)

Impact of a Vertically Polarized Undulator on LCLS Hard X-ray Experiments

Energy Technology Data Exchange (ETDEWEB)

Fritz, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2014-11-14

The LCLS-II project will install two variable gap, horizontally polarized undulators into the LCLS undulator hall. One undulator is designed to produce soft x-rays spanning an energy range of 200-1250 eV (SXU) while the other is designed for the hard spectral range of 1-25 keV (HXU). The hard x-ray LCLS instruments (X-ray Pump- Probe [XPP], X-ray correlation Spectroscopy [XCS], Coherent X-ray Imaging [CXI], Matter in Extreme Conditions [MEC]) will be repurposed to operate on the HXU line while two new soft x-ray beamlines will be created for the SXU line. An alternate HXU undulator design is being considered that could provide advantages over the present design choice. In particular, the project team is collaborating with Argonne National Laboratory to develop a vertically polarized undulator (VPU). A 1-m prototype VPU device was successfully constructed this year and a full size prototype is in process. A decision to alter the project baseline, which is the construction of a horizontally polarized device, must be made in the coming weeks to not impact the present project schedule. Please note that a change to the soft x-ray undulator is not under discussion at the moment.

A short period undulator for MAX

International Nuclear Information System (INIS)

Ahola, H.; Meinander, T.

1992-01-01

A hybrid undulator for generation of high brilliance synchrotron radiation in the photon energy range of 60--600 eV at the 550 MeV electron storage ring MAX in Lund, Sweden has been designed and built at the Technical Research Centre of Finland in close collaboration with MAX-lab of Lund University. At the rather modest electron energy of MAX this photon energy range can be reached only by an undulator featuring a fairly short period and the smallest possible magnetic gap. Even then, higher harmonics (up to the 13th) of the radiation spectrum must be utilized. An optimization of the magnetic design resulted in a hybrid configuration of NdFeB magnets and soft iron poles with a period of 24 mm and a minimum magnetic gap of 7--10 mm. A variable-gap vacuum chamber allows reduction of the vacuum gap from a maximum of 20 mm, needed for injection, down to 6 mm during stored beam operation. A special design of this chamber permits a magnetic gap between pole tips that is only 1 mm larger than the vacuum gap. Adequate field uniformity was ensured by calibration of magnets to equal strength at their true operating point and verification of the homogeneity of their magnetization. Magnetic measurements included Hall probe scans of the undulator field and flip coil evaluations of the field integral

Modeling the North American vertical datum of 1988 errors in the conterminous United States

Science.gov (United States)

Li, X.

2018-02-01

A large systematic difference (ranging from -20 cm to +130 cm) was found between NAVD 88 (North AmericanVertical Datum of 1988) and the pure gravimetric geoid models. This difference not only makes it very difficult to augment the local geoid model by directly using the vast NAVD 88 network with state-of-the-art technologies recently developed in geodesy, but also limits the ability of researchers to effectively demonstrate the geoid model improvements on the NAVD 88 network. Here, both conventional regression analyses based on various predefined basis functions such as polynomials, B-splines, and Legendre functions and the Latent Variable Analysis (LVA) such as the Factor Analysis (FA) are used to analyze the systematic difference. Besides giving a mathematical model, the regression results do not reveal a great deal about the physical reasons that caused the large differences in NAVD 88, which may be of interest to various researchers. Furthermore, there is still a significant amount of no-Gaussian signals left in the residuals of the conventional regression models. On the other side, the FA method not only provides a better not of the data, but also offers possible explanations of the error sources. Without requiring extra hypothesis tests on the model coefficients, the results from FA are more efficient in terms of capturing the systematic difference. Furthermore, without using a covariance model, a novel interpolating method based on the relationship between the loading matrix and the factor scores is developed for predictive purposes. The prediction error analysis shows that about 3-7 cm precision is expected in NAVD 88 after removing the systematic difference.

Modeling the North American vertical datum of 1988 errors in the conterminous United States

Directory of Open Access Journals (Sweden)

Li X.

2018-02-01

Full Text Available A large systematic difference (ranging from −20 cm to +130 cm was found between NAVD 88 (North AmericanVertical Datum of 1988 and the pure gravimetric geoid models. This difference not only makes it very difficult to augment the local geoid model by directly using the vast NAVD 88 network with state-of-the-art technologies recently developed in geodesy, but also limits the ability of researchers to effectively demonstrate the geoid model improvements on the NAVD 88 network. Here, both conventional regression analyses based on various predefined basis functions such as polynomials, B-splines, and Legendre functions and the Latent Variable Analysis (LVA such as the Factor Analysis (FA are used to analyze the systematic difference. Besides giving a mathematical model, the regression results do not reveal a great deal about the physical reasons that caused the large differences in NAVD 88, which may be of interest to various researchers. Furthermore, there is still a significant amount of no-Gaussian signals left in the residuals of the conventional regression models. On the other side, the FA method not only provides a better not of the data, but also offers possible explanations of the error sources. Without requiring extra hypothesis tests on the model coefficients, the results from FA are more efficient in terms of capturing the systematic difference. Furthermore, without using a covariance model, a novel interpolating method based on the relationship between the loading matrix and the factor scores is developed for predictive purposes. The prediction error analysis shows that about 3-7 cm precision is expected in NAVD 88 after removing the systematic difference.

Development of a Planar Undulator

International Nuclear Information System (INIS)

Deyhim, Alex; Johnson, Eric; Kulesza, Joe; Lyndaker, Aaron; Waterman, Dave; Eisert, Dave; Green, Michael A.; Rogers, Greg; Blomqvist, K. Ingvar

2007-01-01

The design of a planar pure permanent magnet undulator is presented. The design requirements and mechanical difficulties for holding, positioning, and driving the magnetic arrays are explored. The structural, thermal, and electrical considerations that influenced the design are then analyzed. And finally detailed magnetic measurements are presented

Design issues for cryogenic cooling of short period superconducting undulators

International Nuclear Information System (INIS)

Green, M.A.; Dietderich, D.R.; Marks, S.; Prestemon, S.O.; Schlueter, R.D.

2003-01-01

Superconducting insertion devices, which produce periodic magnetic fields, have been built and installed in a number of synchrotron-light source storage-rings. For the most part, these devices have been wigglers, which have relatively long period lengths. This report concerns itself with the special cryogenic issues associated with short period undulators. The motivation for considering the incorporation of superconducting technology in insertion device designs is to achieve higher magnetic fields than can be achieved with more conventional permanent magnet technology. Since the peak field decreases sharply with increased magnet gap to period ratio, the cryogenic design of the magnet system is crucial. In particular, the insulation required for a warm vacuum bore device is impractical for short period undulators. This report describes the issues that are related to a cold bore (∼4 K) and an intermediate temperature bore (30 to 70 K) designs. The criteria for the use of small cryocoolers for cooling a short period undulator are presented. The problems associated with connecting small coolers to an undulator at 4.2 K are discussed

In vacuum undulator task force report

Energy Technology Data Exchange (ETDEWEB)

Hastings, J.B.; Kao, C.C.; Stefan, P. [and others

1998-06-01

Historically the NSLS has been active in R&D for state-of-the-art electron beams, photon beams and x-ray optics. One of the available straight sections has therefore been dedicated to insertion device R&D. Over the past five to seven years a program aimed at exploiting the very small vertical {beta} function in the straight sections has yielded first a prototype small gap undulator (PSGU) and then an in-vacuum undulator (IVUN). The IVUN sources attain a brightness similar to the existing hybrid wigglers in X21 and X25. They radiate significantly lower total power than the wigglers but produce higher power densities. They provide undulator rather than wiggler spectra. Because of the small gaps and small periods there is not much tunability in these devices and they will have to be purpose-built for a specific scientific program. The original IVUN parameters were chosen for in-elastic x-ray scattering, similar to the scientific program on X21. This put the fundamental at 4.6 keV and the third harmonic at 13.8 keV. The question that this new possible insertion device poses is what science programs can best take advantage of this new insertion device source? To answer this, a task force was formed by M. Hart, NSLS Department Chair and charged with identifying viable scientific programs that could seek outside funding to construct IVUN beamlines. The task force concentrated on experimental programs that are presently being pursued on new insertion devices worldwide. For example, x-ray photon correlation spectroscopy, which takes advantage of the large coherent flux from undulator sources, was considered. However, this program was not considered as the highest priority. The general area of protein crystallography, however, is ideal for the IVUN source. The unique electron beam optics that makes the IVUN possible in the first place also makes the IVUN ideal as a source for microdiffraction.

Characterization of undulator radiation at the Photon Factory

International Nuclear Information System (INIS)

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

1986-01-01

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. (orig.)

Characterization of undulator radiation at the photon factory

Science.gov (United States)

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.

First undulators for the Advanced Light Source

International Nuclear Information System (INIS)

Hoyer, E.; Akre, J.; Chin, J.

1993-05-01

The first three undulators, each 4.6 m in length, for the Advanced Light source (ALS) at Lawrence Berkeley Laboratory (LBL), are near completion and are undergoing qualification tests before installation into the storage ring. Two devices have 5.0-cm period lengths, 89 periods, and achieve an effective field of 0.85 T at the 14 mm minimum magnetic gap. The other device has a period length of 8.0 cm, 55 periods, and an effective field of 1.2 T at the minimum 14 mm gap. Measurements on the first 5 cm period device show the uncorrelated field errors to be 0.23%, which is less than the required 0.25%. Measurements of gap control show reproducibility of ±5 microns or better. The first vacuum chamber, 5.0 m long, is flat to within 0.53 mm over the 4.6 m magnetic structure section and a 4 x 10 -11 Torr pressure was achieved during vacuum tests. Device description, fabrication, and measurements are presented

Altimetry, bathymetry and geoid variations at the Gavdos permanent Cal/Val facility

DEFF Research Database (Denmark)

Mertikas, Stelios P.; Daskalakis, Antonis; Tziavos, Ilias N.

2013-01-01

The aim of this work has been to examine the relationship of steep bathymetry in the coastal areas around the permanent Cal/Val facility of Gavdos, and their influence on the produced calibration values for the Jason-2 satellite altimeter. The paper describes how changes in seafloor topography...... (from 200 to 3500m depth over a distance of 10km) are reflected on the determined altimeter parameters using different reference surfaces for satellite calibration. Finally, it describes the relation between these parameter trends and the region’s local characteristics.Using 3.5years of Jason-2...... to be related to the general oceanographic circulation, but others of short wavelength (in the order of 1km) are because of the insufficient geoid model resolution. Along Pass No. 109, the concealed effect of bathymetry on the geoid has produced a slope of 3.1cm over 14–21km from Gavdos. Along the other Pass No...

General design of the layout for new undulator-only beamline front ends

International Nuclear Information System (INIS)

Shu Deming; Ramanathan, Mohan; Kuzay, Tuncer M.

2001-01-01

A great majority of the Advanced Photon Source (APS) users have chosen an undulator as the only source for their insertion device beamline. Compared with a wiggler source, the undulator source has a much smaller horizontal divergence, providing us with an opportunity to optimize the beamline front-end design further. In this paper, the particular designs and specifications, as well as the optical and bremsstrahlung ray-tracing analysis of the new APS front ends for undulator-only operation are presented

Stimulated bremsstrahlung of soft x-ray in a longitudinal undulating electric field

International Nuclear Information System (INIS)

Kim, S.H.

1991-01-01

It is shown that a high-energy electron beam injected into a longitudinal undulating electric field (electric undulator) in the field direction can emit a laser light in the field direction through both stimulated and unstimulated free-electron two-quantum Stark emission. Based on the momentum and energy conservation laws and the time-reversal invariance of the transition probability, a new quantum kinetic equation for the net energy transfer from an electron to the laser wave is derived. By using this equation, the photon concept, and the transition probability calculated by the Dirac equation, the gain spectrum and wavelength of the free-electron laser using the electric undulator are derived. The gain appears to scale as the inverse of the electron beam energy and the cube of the wavelength of the electric undulator

A detailed gravimetric geoid of North America, the North Atlantic, Eurasia, and Australia

Science.gov (United States)

Marsh, J. G.

1973-01-01

A computer program was developed for the calculation of a goid based upon a combination of satellite and surface gravity data. A detailed gravimetric geoid of North America, the North Atlantic, Eurasia, and Australia was derived by using this program.

Global and regional seasonal variations of the geoid detected by GRACE

Czech Academy of Sciences Publication Activity Database

Kostelecký, J.; Bezděk, Aleš; Klokočník, Jaroslav

2013-01-01

Roč. 10, č. 3 (2013), s. 285-291 ISSN 1214-9705 R&D Projects: GA ČR GA13-36843S Grant - others:EU(XE) NTIS CZ1.05/1.1.00/02.0090 Institutional support: RVO:67985815 Keywords : GRACE mission * seasonal variations * geoid Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.667, year: 2013

Local Marine Geoid Variations and Jason-2 Bias Determination using the Gavdos Permanent Cal/Val Facility

DEFF Research Database (Denmark)

Mertikas, S. P.; Daskalakis, A.; Tziavos, I. N.

2012-01-01

This work outlines how changes in steep bathymetry (from 200 m to 3500 m depth over a distance of 10 km) are reflected on the determined sea surface anomalies at the Gavdos site used for satellite altimeter calibration. After almost 4 years of Jason-2 calibration activities, it has been observed......, but others are related to under-sampling of the Earth's gravity field due to the resolution of the geoid model. New reference surfaces for calibration have thus emerged. Finally, new updated values for the Jason-2 altimeter bias have been determined as 191.81 ± 2.80 mm with the geoid model and as 181.51 ± 2...

Development of cryogenic undulators with PrFeB magnets at SOLEIL

Energy Technology Data Exchange (ETDEWEB)

Valléau, M., E-mail: valleau@synchrotron-soleil.fr; Benabderrahmane, C.; Briquez, F.; Berteaud, P.; Tavakoli, K.; Zerbib, D.; Chapuis, L.; Marteau, F.; Marcouillé, O.; El Ajjouri, T.; Vétéran, J.; Sharma, G.; Tilmont, M.; Castro, J. Da Silva; N’Guyen, M.-H.; Béchu, N.; Rommeluère, P.; Louvet, M.; Nadji, A.; Herbeaux, C. [Synchrotron-Soleil, L’Orme des Merisisers, 91192 BP 34, Gif Sur Yvette (France); and others

2016-07-27

Short period high field undulators are of interest for X-ray brilliance enhancement in synchrotron radiation applications and for compact Free Electron Lasers. Cryogenic in-vacuum undulators [1] are one of the possible solutions. At SOLEIL, PrFeB magnets were directly chosen, even if still under development at that time. Indeed, they enable to avoid the spin transition reorientation phenomenon which occurs with NdFeB magnets [2] and the magnets can be cooled down directly at 77 K. The first selected grade CR53 from Hitachi presents a remanence of 1.35 T at 293 K and 1.57 T at 77 K, with a coercivity of 1355 kA/m at 293 K and 6000 kA/m at 77 K. A 2 m long cryogenic undulator of period 18 mm was first built in-house, with a specific Hall probe bench directly installed in the final vacuum chamber. This first cryogenic undulator has been in operation on the storage ring for 4 years [3]. A second U18 cryo-ready undulator using a slightly different magnet grade with a higher coercivity and modules with magnets surrounded by two half poles for easier magnetic optimization is under construction. A third 3 m long cryo-ready undulator U15 with a period of 15 mm is under development. It will be first used for the LUNEX5 FEL [4, 5] project (COXINEL demonstration of FEL amplification with a laser wakefield acceleration [6]). The measurement bench will include a correction of the Hall probe position and angle, the field integrals will be measured with a stretched wire.

Construction of CHESS compact undulator magnets at Kyma

Science.gov (United States)

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.

Electron Signal Detection for the Beam-Finder Wire of the Linac Coherent Light Source Undulator

International Nuclear Information System (INIS)

Wu, Juhao; Emma, P.; Field, R.C.; SLAC

2006-01-01

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. The tight tolerances for positioning the electron beam close to the undulator axis calls for the introduction of Beam Finder Wire (BFW) device. A BFW device close to the upstream end of the undulator segment and a quadrupole close to the down stream end of the undulator segment will allow a beam-based undulator segment alignment. Based on the scattering of the electrons on the BFW, we can detect the electron signal in the main dump bends after the undulator to find the beam position. We propose to use a threshold Cherenkov counter for this purpose. According to the signal strength at such a Cherenkov counter, we then suggest choice of material and size for such a BFW device in the undulator

Mechanical design and fabrication of a prototype undulator for Indus-2

International Nuclear Information System (INIS)

Veerabhadhraiah, T.; Sinha, Gautam; Prabhu, S.S.

2011-01-01

An Apple II type undulator is proposed for 2.5 GeV SRS. For initial studies of magnetic parameters and manufacturing feasibilities, a 6 periods prototype undulator of period length 72 mm and pole gap 20 mm is under development. Mechanical structure with stringent tolerances is required to achieve the required field quality. Stress analysis has been done to study the deflection under the magnetic forces. The prototype structure along with the magnet block holders has been made and mechanical dimensions and geometric tolerances have been measured. In this paper we present the preliminary mechanical design and assembly of static parts of prototype undulator structure. (author)

Variation of Marine Geoid Due to Ocean Circulation and Sea Level Change

Science.gov (United States)

Chu, P. C.

2017-12-01

Sea level (S) change and ocean circulation largely affect the gravity field and in turns the marine geoid (N). Difference between the two, D = S - N, is the dynamic ocean topography (DOT), whose gradient represents the large-scale surface geostrophic circulations. Thus, temporal variability of marine geoid (δN) is caused by the sea level change (δS) and the DOT variation (δD), δN = δS - δD. Here, δS is identified from temporally varying satellite altimeter measures; δD is calculated from the change of DOT. For large-scale processes with conservation of potential vorticity, the geostrophic flows take minimum energy state. Based on that, a new elliptic equation is derived in this study to determine D. Here, H is the water depth; and (X, Y) are forcing functions calculated from the in-situ density. The well-posed elliptic equation is integrated numerically on 1o grids for the world oceans with the boundary values taken from the mean DOT (1993-2006) field at the NASA/JPL website: https://grace.jpl.nasa.gov/data/get-data/dynamic-ocean-typography/, the forcing function F calculated from the three-dimensional temperature and salinity of the NOAA National Centers for Environmental Information (NCEI) World Ocean Atlas 2013 version 2, and sea-floor topography (H) from the NOAA ETOPO5. The numerical solution compares reasonably well (relative root mean square difference of 0.09) with the NASA/JPL satellite observation of the difference between the time-averaged sea surface height and the geoid. In-situ ocean measurements of temperature, salinity, and velocity have also rapidly advanced such that the global ocean is now continuously monitored by near 4,000 free-drifting profiling floats (called Argo) from the surface to 2000 m depth with all data being relayed and made publicly available within hours after collection (http://www.argo.ucsd.edu/). This provides a huge database of temperature and salinity and in turns the forcing function F for the governing elliptic

Quantitative investigation of linear arbitrary polarization in an APPLE-II undulator.

Science.gov (United States)

Hand, Matthew; Wang, Hongchang; Maccherozzi, Francesco; Apollonio, Marco; Zhu, Jingtao; Dhesi, Sarnjeet S; Sawhney, Kawal

2018-03-01

Insertion devices are utilized at synchrotron radiation facilities around the world for their capability to provide a high-brilliance X-ray beam. APPLE-II type undulators are especially important for their capacity to switch between a variety of photon beam polarization states. A high-precision soft X-ray polarimeter has been used to investigate the polarization calibration of an APPLE-II undulator (period length λ u = 64 mm) installed on beamline I06 at Diamond Light Source. Systematic measurement of the beam polarization state at a range of linear arbitrary angles has been compared with the expected result for a given set of undulator gap and row phase parameters calculated from theory. Determination of the corresponding Stokes-Poincaré parameters from the measured data reveals a discrepancy between the two. The limited number of energy/polarization combinations included in the undulator calibration tables necessitates the use of interpolated values for the missing points which is expected to contribute to the discrepancy. However, by modifying the orbit of the electron beam through the undulator by at least 160 µm it has been found that for certain linear polarizations the discrepancies can be corrected. Overall, it is suggested that complete correction of the Stokes-Poincaré parameters for all linear angles would require alteration of both these aspects.

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-06-25

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. We then used the kick maps obtained by other methods to simulate the effect of the undulator on injection and lifetime.

Development of a superconducting undulator for the APS

International Nuclear Information System (INIS)

Ivanyushenkov, Y; Abliz, M; Doose, C; Fuerst, J; Hasse, Q; Kasa, M; Trakhtenberg, E; Vasserman, I; Gluskin, E; Lev, V; Mezentsev, N; Syrovatin, V; Tsukanov, V

2013-01-01

As the western hemisphere's premier x-ray synchrotron radiation source, the Advanced Photon Source (APS) continues to advance the state of the art in insertion device technology in order to maintain record high brightness, especially in the hard x-ray wavelength region. Due to the unique bunch pattern used for normal APS operations and its ultimate capabilities, the APS has chosen superconducting technology for its future hard x-ray undulator sources. In the last several years, the APS in collaboration with the Budker Institute of Nuclear Physics has being developing the technology for planar, small-period superconducting undulators (SCUs). These developments include the design and construction of several prototypes and the construction of the necessary mechanical, vacuum, and cryogenic infrastructure at the APS site. Several prototypes of the SCU magnetic structure have been built and tested. The first SCU is assembled and will be installed in the APS storage ring at the end of 2012. Expected SCU performance in terms of x-ray brightness should noticeably exceed that of existing APS undulators. Immediately after commissioning, the SCU will be used at APS Sector 6 as the radiation source for high-energy x-ray studies.

KIAE-1.5-3 undulator performance

Energy Technology Data Exchange (ETDEWEB)

Varfolomeev, A.A.; Ivanchenko, S.N.; Khlebnikov, A.S. [Kurchatov Institute, Moscow (Russian Federation)] [and others

1995-12-31

Hybrid type undulator with 60 periods of {lambda}{sub w} = 1.5 cm and tunable gap in wide range has been designed and manufactured. Additional side magnet arrays provide high magnetic field (near Halbach limit) along with transverse field profiles for e.b. focusing.

Observation of the undulator radiation from the positron beam

International Nuclear Information System (INIS)

Maezawa, Hideki.

1986-02-01

A spectral measurement of the 1st harmonic of the undulator radiation emitted from positron beam was made on Dec. 21, 1985 during a test operation of the Photon Factory storage ring with the 2.5 GeV positron beam which was stored up to 5.5 mA. In comparison to the same measurement performed with the electron beam, no appreciable difference in the spectral properties of the undulator radiation was found between the two cases under the condition of the low beam current of a few mA. (author)

Blade-type X-ray beam position monitors for SPring-8 undulator beamlines

CERN Document Server

Aoyagi, H; Kitamura, H

2001-01-01

The X-ray beam position monitors had been designed and installed for SPring-8 insertion device beamlines. These monitors are being utilized for photon beam diagnostics. The beam from the standard undulator in SPring-8 has the total power of 11 kW and the power density of 470 kW/mrad sup 2 , typically. Each monitor has four CVD diamond blades coated with metal for detector heads. We have already introduced three styles of monitors to match various insertion devices in SPring-8. A standard style, or a fixed-blade style, is used mainly for a standard in-vacuum undulator beamlines. A horizontal-blade-drive style and a four-blade-drive style are used for beamlines of a wiggler and a twin helical undulator that have wide power distributions, and for figure-8 undulators that have asymmetric power distributions, respectively. This report describes the design and the structure of these monitors and the beam-tests for the photon beam diagnostics in detail.

Study for a 6 GeV undulator based synchrotron radiation source

International Nuclear Information System (INIS)

Vignola, G.; Barton, M.; Blumberg, R.; Galayda, J.; Krinsky, S.; Luccio, A.; Pellegrini, C.; van Steenbergen, A.; Wang, J.

1985-01-01

A partial study for a 6 GeV undulator based synchrotron radiation source for production of high brightness undulator radiation, in the A region, is presented. The basic lattice adopted for the storage ring is a hybrid FODO Chasman-Green lattice, making use of gradient in the dipoles. We discuss also the e beam current limits and the injection parameters

Nearly copropagating sheared laser pulse FEL undulator for soft x-rays

International Nuclear Information System (INIS)

Lawler, J E; Yavuz, D; Bisognano, J; Bosch, R A; Chiang, T C; Green, M A; Jacobs, K; Miller, T; Wehlitz, R; York, R C

2013-01-01

A conceptual design for a soft x-ray free-electron laser (FEL) using a short-pulsed, high energy near infrared laser undulator and a low-emittance modest-energy (∼170 MeV) electron beam is described. This low-cost design uses the laser undulator beam in a nearly copropagating fashion with respect to the electron beam, instead of the traditional ‘head-on’ fashion. The nearly copropagating geometry reduces the Doppler shift of scattered radiation to yield soft, rather than hard x-rays. To increase the FEL gain a sheared laser pulse from a Ti : sapphire or other broadband laser is used to extend the otherwise short interaction time of the nearly copropagating laser undulator beam with a relativistic electron beam. (paper)

On quantum effects in spontaneous emission by a relativistic electron beam in an undulator

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-02-15

Robb and Bonifacio (2011) claimed that a previously neglected quantum effect results in noticeable changes in the evolution of the energy distribution associated with spontaneous emission in long undulators. They revisited theoretical models used to describe the emission of radiation by relativistic electrons as a continuous diffusive process, and claimed that in the asymptotic limit for a large number of undulator periods the evolution of the electron energy distribution occurs as discrete energy groups according to Poisson distribution. We show that these novel results have no physical sense, because they are based on a one-dimensional model of spontaneous emission and assume that electrons are sheets of charge. However, electrons are point-like particles and, as is well-known, the bandwidth of the angular-integrated spectrum of undulator radiation is independent of the number of undulator periods. If we determine the evolution of the energy distribution using a three-dimensional theory we find the well-known results consistent with a continuous diffusive process. The additional pedagogical purpose of this paper is to review how quantum diffusion of electron energy in an undulator with small undulator parameter can be simply analyzed using the Thomson cross-section expression, unlike the conventional treatment based on the expression for the Lienard-Wiechert fields. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Hideki, E-mail: hideki@slri.or.th; Chaichuay, Sarunyu; Sudmuang, Porntip; Rattanasuporn, Surachet; Jenpiyapong, Watcharapon; Supruangnet, Ratchadaporn; Chanlek, Narong [Synchrotron Light Research Institute, Muang, Nakhon Ratchasima 30000 (Thailand); Songsiriritthigul, Prayoon [School of Physics, Suranaree University of Technology, Muang, Nakhon Ratchasima 30000 (Thailand)

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 evaluated 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.

Different ways to handle topography in practical geoid determination

DEFF Research Database (Denmark)

Dahl, O.C.; Forsberg, René

1999-01-01

In this paper two different methods of how to handle topography in geoid determination is investigated. First method employs the Residual Terrain Model (RTM) remove-restore technique and yields the quasigeoid, whereas the second method is the classical Helmert condensation method, yielding...... the topography was represented by either a detailed (100 m) or a coarse (1000 m) digital terrain model. The inclusion of bathymetry in the terrain model was also investigated. Even if two different methods were used, they produced almost identical results at the 5 cm level in the mountains, but small systematic...

Improvement of the crossed undulator design for effective circular polarization control in X-ray FELs

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2011-01-15

The production of X-ray radiation with a high degree of circular polarization constitutes an important goal at XFEL facilities. A simple scheme to obtain circular polarization control with crossed undulators has been proposed so far. In its simplest configuration the crossed undulators consist of pair of short planar undulators in crossed position separated by an electromagnetic phase shifter. An advantage of this configuration is a fast helicity switching. A drawback is that a high degree of circular polarization (over 90 %) can only be achieved for lengths of the insertion devices significantly shorter than the gain length, i.e. at output power significantly lower than the saturation power level. The obvious and technically possible extension considered in this paper, is to use a setup with two or more crossed undulators separated by phase shifters. This cascade crossed undulator scheme is distinguished, in performance, by a fast helicity switching, a high degree of circular polarization (over 95%) and a high output power level, comparable with the saturation power level in the baseline undulator at fundamental wavelength. We present feasibility study and exemplifications for the LCLS baseline in the soft X-ray regime. (orig.)

Delta undulator for Cornell energy recovery linac

Directory of Open Access Journals (Sweden)

Alexander B. Temnykh

2008-12-01

Full Text Available In anticipation of a new era of synchrotron radiation sources based on energy recovery linac techniques, we designed, built, and tested a short undulator magnet prototype whose features make optimum use of the unique conditions expected in these facilities. The prototype has pure permanent magnet (PPM structure with 24 mm period, 5 mm diameter round gap, and is 30 cm long. In comparison with conventional undulator magnets it has the following: (i full x-ray polarization control.—It may generate varying linear polarized as well as left and right circular polarized x rays with photon flux much higher than existing Apple-II–type devices. (ii 40% stronger magnetic field in linear and approximately 2 times stronger in circular polarization modes. This advantage translates into higher x-ray flux. (iii Compactness.—The prototype can be enclosed in a ∼20  cm diameter cylindrical vacuum vessel. These advantages were achieved through a number of unconventional approaches. Among them is control of the magnetic field strength via longitudinal motion of the magnet arrays. The moving mechanism is also used for x-ray polarization control. The compactness is achieved using a recently developed permanent magnet soldering technique for fastening PM blocks. We call this device a “Delta” undulator after the shape of its PM blocks. The presented article describes the design study, various aspects of the construction, and presents some test results.

Elementary excitations of biomembranes: Differential geometry of undulations in elastic surfaces

Energy Technology Data Exchange (ETDEWEB)

Hemmen, J. Leo van [Physik Department, Technical University of Munich, 85747 Garching (Germany)]. E-mail: lvh@tum.de; Leibold, Christian [Physik Department, Technical University of Munich, 85747 Garching (Germany)

2007-06-15

Biomembrane undulations are elementary excitations in the elastic surfaces of cells and vesicles. As such they can provide surprising insights into the mechanical processes that shape and stabilize biomembranes. We explain how naturally these undulations can be described by classical differential geometry. In particular, we apply the analytical formalism of differential-geometric calculus to the surfaces generated by a cell membrane and underlying cytoskeleton. After a short derivation of the energy due to a membrane's elasticity, we show how undulations arise as elementary excitations originating from the second derivative of an energy functional. Furthermore, we expound the efficiency of classical differential-geometric formalism to understand the effect of differential operators that characterize processes involved in membrane physics. As an introduction to concepts the paper is self-contained and rarely exceeds calculus level.

Elementary excitations of biomembranes: Differential geometry of undulations in elastic surfaces

International Nuclear Information System (INIS)

Hemmen, J. Leo van; Leibold, Christian

2007-01-01

Biomembrane undulations are elementary excitations in the elastic surfaces of cells and vesicles. As such they can provide surprising insights into the mechanical processes that shape and stabilize biomembranes. We explain how naturally these undulations can be described by classical differential geometry. In particular, we apply the analytical formalism of differential-geometric calculus to the surfaces generated by a cell membrane and underlying cytoskeleton. After a short derivation of the energy due to a membrane's elasticity, we show how undulations arise as elementary excitations originating from the second derivative of an energy functional. Furthermore, we expound the efficiency of classical differential-geometric formalism to understand the effect of differential operators that characterize processes involved in membrane physics. As an introduction to concepts the paper is self-contained and rarely exceeds calculus level

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

Science.gov (United States)

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.

A concept of a new undulator that will generate irrational higher harmonics in synchrotron radiation

International Nuclear Information System (INIS)

Hashimoto, Shinya; Sasaki, Shigemi

1994-03-01

A preliminary consideration has been made on an undulator with magnetic poles quasi-periodically aligned along the path of electron beams to discriminate the rational higher harmonics of radiation that are harmful in some synchrotron radiation experiments. The harmonics with irrational ratios in energy generated by the undulator is never simultaneously reflected by a crystal monochromator in the same orientation. A combination of the new undulator and high-resolution crystal monochromator is expected to be very useful on beamlines of high energy radiation in which X-ray mirrors are useless because of too small critical angles of total reflection. Further, a possibility of manufacturing the new undulator has been discussed. (author)

The full potential of the baseline SASE undulators of the European XFEL

International Nuclear Information System (INIS)

Agapov, Ilya; Geloni, Gianluca; Feng, Guangyao; Kocharyan, Vitali; Saldin, Evgeni; Serkez, Svitozar; Zagorodnov, Igor

2014-04-01

The output SASE characteristics of the baseline European XFEL, recently used in the TDRs of scientific instruments and X-ray optics, have been previously optimized assuming uniform undulators without considering the potential of undulator tapering in the SASE regime. Here we demonstrate that the performance of European XFEL sources can be significantly improved without additional hardware. The procedure simply consists in the optimization of the undulator gap configuration for each X-ray beamline. Here we provide a comprehensive description of the soft X-ray photon beam properties as a function of wavelength and bunch charge. Based on nominal parameters for the electron beam, we demonstrate that undulator tapering allows one to achieve up to a tenfold increase in peak power and photon spectral density in the conventional SASE regime. We illustrate this fact for the SASE3 beamline. The FEL code Genesis has been extensively used for these studies. Based on these findings we suggest that the requirements for the SASE3 instrument (SCS, SQS) and for the SASE3 beam transport system be updated.

Influence of the synchrotron radiation on particle dynamics in a rectangular undulator

International Nuclear Information System (INIS)

Chin, Yong Ho.

1989-03-01

This paper is concerned with the synchrotron radiation from an undulating electron beam in a rectangular waveguide. It is shown analytically and numerically that the radiated energy spectrum may differ significantly from the free space result when the undulator length divided by the Lorentz factor of the electron beam is larger than the transverse size of the waveguide. The undulator radiation is identified with the awake field in beam instabilities. The concepts of wake function and impedance are introduced to formulate the present problem in the same manner as the beam instability problem. It is shown that the obtained impedances satisfy the Panofsky-Wenzel theorem and other properties inevitable for wake fields. 5 refs., 2 figs

A dynamic method for continuously measuring magnetic field profiles in planar micropole undulators with submillimeter gaps

International Nuclear Information System (INIS)

Tatchyn, R.; Oregon Univ., Eugene

1989-01-01

Conventional techniques for measuring magnetic field profiles in ordinary undulators rely predominantly on Hall probes for making point-by-point static measurements. As undulators with submillimeter periods and gaps become available, such techniques will start becoming untenable, due to the relative largeness of conventional Hall probe heads and the rapidly increasing number of periods in devices of fixed length. In this paper a method is presented which can rapidly map out field profiles in undulators with periods and gaps extending down to the 100 μm range and beyond. The method, which samples the magnetic field continuously, has been used successfully in profiling a recently constructed 726 μm period undulator, and seems to offer some potential advantages over conventional Hall probe techniques in measuring large-scale undulator fields as well. (orig.)

Second crystal cooling on cryogenically cooled undulator and wiggler double crystal monochromators

International Nuclear Information System (INIS)

Knapp, G. S.

1998-01-01

Simple methods for the cooling of the second crystals of cryogenically cooled undulator and wiggler double crystal monochromators are described. Copper braids between the first and second crystals are used to cool the second crystals of the double crystal monochromators. The method has proved successful for an undulator monochromator and we describe a design for a wiggler monochromator

Observational constraints on undulant cosmologies

Energy Technology Data Exchange (ETDEWEB)

Barenboim, Gabriela; /Valencia U.; Mena Requejo, Olga; Quigg, Chris; /Fermilab

2005-10-01

In an undulant universe, cosmic expansion is characterized by alternating periods of acceleration and deceleration. We examine cosmologies in which the dark-energy equation of state varies periodically with the number of e-foldings of the scale factor of the universe, and use observations to constrain the frequency of oscillation. We find a tension between a forceful response to the cosmic coincidence problem and the standard treatment of structure formation.

Fabrication of mm-wave undulator cavities using deep x-ray lithography

International Nuclear Information System (INIS)

Song, J.J.; Kang, Y.W.; Kustom, R.L.; Lai, B.; Nassiri, A.; Feinerman, A.D.; White, V.; Well, G.M.

1995-01-01

The possibility of fabricating mm-wave radio frequency cavities (100-300 GHz) using deep x-ray lithography (DXRL) is being investigated. The fabrication process includes manufacture of precision x-ray masks, exposure of positive resist by x-ray through the mask, resist development, and electroforming of the final microstructure. Highly precise, two-dimensional features can be machined onto wafers using DXRL. Major challenges are: fabrication of the wafers into three-dimensional rf structures; alignment and overlay accuracy of structures; adhesion of the PMMA on the copper substrate; and selection of a developer to obtain high resolution. Rectangular cavity geometry is best suited to this fabrication technique. A 30- or 84-cell 108-GHz mm-wave structure can serve as an electromagnetic undulator. A mm-wave undulator, which will be discussed later, may have special features compared to the conventional undulator. First harmonic undulator radiation at 5.2 KeV would be possible using the Advanced Photon Source (APS) linac system, which provides a low-emittance electron beam by using an rf thermionic gun with an energy as high as 750-MeV. More detailed rf simulation, heat extraction analysis, beam dynamics using a mm-wave structure, and measurements on lOx larger scale models can be found in these proceedings

Enhanced coherent undulator radiation from bunched electron beams

International Nuclear Information System (INIS)

Berryman, K.W.; Crosson, E.R.; Ricci, K.N.; Smith, T.I.

1996-01-01

When energetic bunches of electrons traverse an undulator field, they can spontaneously emit radiation both coherently and incoherently. Although it has generally been assumed that undulator radiation is incoherent at wavelengths short compared to the longitudinal size of the electron bunch, several recent observations have proved this assumption false. Furthermore, the appearance of coherent radiation is often accompanied by a significant increase in radiated power. Here we report observations of strongly enhanced coherent spontaneous radiation together with direct measurements, using transition radiation techniques, of the electron distributions responsible for the coherent emission. We also report demonstrated enhancements in the predicted spontaneous radiated power by as much as 6x10 4 using electron bunch compression. copyright 1996 American Institute of Physics

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

Science.gov (United States)

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.

Calculated Performance Of The Variable-Polarization Undulator Upgrade To The Daresbury SRS Soft X-Ray Undulator Beamline

International Nuclear Information System (INIS)

Roper, Mark D.; Bird, Daniel T.

2004-01-01

The soft x-ray beamline 5U1 on the Daresbury Laboratory SRS currently uses a planar undulator, producing linearly polarized radiation in the range 100 to 1000 eV. The undulator is soon to be replaced by a variable-polarization device of the Apple II design. The aim is to produce circularly polarized light in the energy range 265 to 1000 eV, covering the K-edges of C, N and O, and the first row transition element L-edges. This will greatly enhance the provision of circularly polarized soft-x-rays on the SRS and open up new opportunities for experimenters. The device will also produce linear polarization with a selectable angle of polarization with respect to the orbit plane, which is currently unavailable on the SRS. In order to provide the coverage over this energy range, we are exploiting the relatively large emittance of the SRS to allow us to use the second and third harmonics even in circular polarization mode. This paper presents the expected beamline output in various polarization modes and the predicted degree of polarization

Brilliant radiation sources by laser-plasma accelerators and optical undulators

Energy Technology Data Exchange (ETDEWEB)

Debus, Alexander

2012-09-06

This thesis investigates the use of high-power lasers for synchrotron radiation sources with high brilliance, from the EUV to the hard X-ray spectral range. Hereby lasers accelerate electrons by laser-wakefield acceleration (LWFA), act as optical undulators, or both. Experimental evidence shows for the first time that LWFA electron bunches are shorter than the driving laser and have a length scale comparable to the plasma wavelength. Furthermore, a first proof of principle experiment demonstrates that LWFA electrons can be exploited to generate undulator radiation. Building upon these experimental findings, as well as extensive numerical simulations of Thomson scattering, the theoretical foundations of a novel interaction geometry for laser-matter interaction are developed. This new method is very general and when tailored towards relativistically moving targets not being limited by the focusability (Rayleigh length) of the laser, while it does not require a waveguide. In a theoretical investigation of Thomson scattering, the optical analogue of undulator radiation, the limits of Thomson sources in scaling towards higher peak brilliances are highlighted. This leads to a novel method for generating brilliant, highly tunable X-ray sources, which is highly energy efficient by circumventing the laser Rayleigh limit through a novel traveling-wave Thomson scattering (TWTS) geometry. This new method suggests increases in X-ray photon yields of 2-3 orders of magnitudes using existing lasers and a way towards efficient, optical undulators to drive a free-electron laser. The results presented here extend far beyond the scope of this work. The possibility to use lasers as particle accelerators, as well as optical undulators, leads to very compact and energy efficient synchrotron sources. The resulting monoenergetic radiation of high brilliance in a range from extreme ultraviolet (EUV) to hard X-ray radiation is of fundamental importance for basic research, medical

Brilliant radiation sources by laser-plasma accelerators and optical undulators

International Nuclear Information System (INIS)

Debus, Alexander

2012-01-01

This thesis investigates the use of high-power lasers for synchrotron radiation sources with high brilliance, from the EUV to the hard X-ray spectral range. Hereby lasers accelerate electrons by laser-wakefield acceleration (LWFA), act as optical undulators, or both. Experimental evidence shows for the first time that LWFA electron bunches are shorter than the driving laser and have a length scale comparable to the plasma wavelength. Furthermore, a first proof of principle experiment demonstrates that LWFA electrons can be exploited to generate undulator radiation. Building upon these experimental findings, as well as extensive numerical simulations of Thomson scattering, the theoretical foundations of a novel interaction geometry for laser-matter interaction are developed. This new method is very general and when tailored towards relativistically moving targets not being limited by the focusability (Rayleigh length) of the laser, while it does not require a waveguide. In a theoretical investigation of Thomson scattering, the optical analogue of undulator radiation, the limits of Thomson sources in scaling towards higher peak brilliances are highlighted. This leads to a novel method for generating brilliant, highly tunable X-ray sources, which is highly energy efficient by circumventing the laser Rayleigh limit through a novel traveling-wave Thomson scattering (TWTS) geometry. This new method suggests increases in X-ray photon yields of 2-3 orders of magnitudes using existing lasers and a way towards efficient, optical undulators to drive a free-electron laser. The results presented here extend far beyond the scope of this work. The possibility to use lasers as particle accelerators, as well as optical undulators, leads to very compact and energy efficient synchrotron sources. The resulting monoenergetic radiation of high brilliance in a range from extreme ultraviolet (EUV) to hard X-ray radiation is of fundamental importance for basic research, medical

An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

Science.gov (United States)

Skourup, Henriette; Farrell, Sinéad Louise; Hendricks, Stefan; Ricker, Robert; Armitage, Thomas W. K.; Ridout, Andy; Andersen, Ole Baltazar; Haas, Christian; Baker, Steven

2017-11-01

State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high-frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multisensor oceanographic time series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04 and DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, intersatellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimeters in parts of the Arctic. While the maximum observed freeboard difference found in the central Arctic was 0.59 m (UCL13 MSS minus EGM2008 GGM), the standard deviation in freeboard differences is 0.03-0.06 m.

Effect of wavelength of fish-like undulation of a hydrofoil in a free ...

Indian Academy of Sciences (India)

Thekkethil Namshad

Abstract. Fish-like undulating body was proposed as an efficient propulsion system, and various mechanisms ... fishes/foil. The present work proposes a unified study for undulating and pitching foil, by varying wavelength k. (from 0.8 to 8.0) of a wave travelling backwards over the ...... and Randall D J (Eds.) Fish physiology.

Effects of wigglers and undulators on beam dynamics

International Nuclear Information System (INIS)

Smith, L.

1986-08-01

Synchrotron light facilities are making ever increasing use of wigglers and undulators, to the extent that these devices are becoming a significant part of the beam optical system of the storage ring itself. This paper presents a theoretical formulation for investigating the effect of wigglers and undulators on beam dynamics in the approximation that the wiggler parameter, K, divided by γ is a small number and that the number of wiggler periods in one device is large. In addition to the linear forces which must be taken into account when tuning and matching the ring, nonlinear stop bends are created, with even orders more serious than odd orders. Some numerical examples are given for devices similar to those proposed for the 1-2 GeV Synchrotron Radiation Source at Lawrence Berkeley Laboratory

X-ray lithography using wiggler and undulator synchrotron-radiation sources

International Nuclear Information System (INIS)

Neureuther, A.R.; Kim, K.J.; Thompson, A.C.; Hoyer, E.

1983-08-01

A systems design approach is used to identify feasible options for wiggler and undulator beam lines for x-ray lithography in the 0.5 to 0.2 μm linewidth region over 5 cm by 5 cm fields. Typical parameters from the Wiggler and Undulator in the Advanced Light Source designed at the Lawrence Berkeley Laboratory are used as examples. Moving from the conventional wavelengths of 4 to 9 A to very soft wavelengths around 15 A is shown to be very promising. The mask absorber thickness can be reduced a factor of three so that 0.2 μm features can be made with a 1:1 mask aspect ratio. The mask heating limited exposure time is also reduced a factor of three to 3 sec/cm 2 . However, extremely thin beam line windows (1/4 mil Be) and mask supports (1 μm Si) must be used. A wiggler beam line design using a small slit window at a scanning mirror appears feasible. A unconventional, windowless differentially pumped beam line with dual deflecting mirrors could be used with an undulator source

Antiaging activity of low molecular weight peptide from Paphia undulate

Science.gov (United States)

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.

An elliptically-polarizing undulator with phase adjustable energy and polarization

International Nuclear Information System (INIS)

Lidia, S.

1993-08-01

The authors present a planar helical undulator designed to produce elliptically polarized light. Helical magnetic fields may be produced by a variety of undulators with four parallel cassettes of magnets. In their design, all cassettes are mounted in two planes on slides so that they may be moved parallel to the electron beam. This allows the undulator to produce x-rays of left- or right-handed elliptical or circular polarization as well as horizontal or vertical linear polarization. In model calculations, they have found that by sliding the top pair of rows with respect to the bottom pair, or the left pair with respect to the right pair, they retain the polarization setting but change the magnetic field strength, and hence the x-ray energy. This allows them to select both energy and polarization by independent phase adjustments alone, without changing the gap between the rows. Such a design may be simpler to construct than an adjustable gap machine. The authors present calculations that model its operation and its effects on an electron beam

Comparison of two superconducting elliptical undulators for generating circularly polarized light

Directory of Open Access Journals (Sweden)

C. S. Hwang

2004-09-01

Full Text Available The potential use of two planar superconducting elliptical undulators—a vertically wound racetrack coil structure and a staggered array structure—to generate a circularly polarized hard x-ray source was investigated. The magnetic poles and wires of the up and down magnet arrays were rotated in alternating directions on the horizontal plane, an elliptical field is generated to provide circularly polarized light in the electron-storage ring and the energy-recovery linac accelerator. Rapid switching between right- and left-circularly polarized radiations is performed using two undulators with oppositely rotated wires and poles. Given a periodic length of 15 mm and a gap of 5 mm, the magnetic-flux densities in the elliptical undulator are B_{z}=1.2   T (B_{x}=0.6   T and B_{z}=0.35   T (B_{x}=0.15   T in the planar vertically wound racetrack coil and the staggered structure with poles rotated by 35° and 25°, respectively. In maximizing the merit of the flux and the width of the effective field region in the two superconducting elliptical undulators, the trade-off rotation angles of the coils and poles are 20° and 5°, for vertically wound racetrack coil and staggered undulators, respectively.

Performance of an undulator for visible and UV FELs at FELI

Energy Technology Data Exchange (ETDEWEB)

Miyauchi, Y.; Zako, A.; Koga, A. [Free Electron Laser Research Institute, Inc., Osaka (Japan)] [and others

1995-12-31

Two infrared free electron lasers (FELs) of the FELI project are now operating in the wavelength range of 1-20{mu}m. A 2.68-m undulator has been constructed for visible and UV FELs covering the wavelength of 1-0.2{mu}m for 100-165 MeV electron beams. It generates alternating, horizontal magnetic field, and wiggles electron beam on a vertical plane. The undulator length and period are 2.68m and 40mm, respectively. The gap of undulator magnets can be changed remotely by using servomotors with an accuracy of 1 {mu}m from the control room. The maximum K-value and related magnetic field strength are 1.9 and 0.5T, respectively, when its gap is set to the minimum value of 16mm. In order to minimize magnetic field reduction due to radiation damage, Sm-Co permanent magnet was adopted. Its structure and the results of magnetic field measurement will be reported.

Software development and its description for Geoid determination based on Spherical-Cap-Harmonics Modelling using digital-zenith camera and gravimetric measurements hybrid data

Science.gov (United States)

Morozova, K.; Jaeger, R.; Balodis, J.; Kaminskis, J.

2017-10-01

Over several years the Institute of Geodesy and Geoinformatics (GGI) was engaged in the design and development of a digital zenith camera. At the moment the camera developments are finished and tests by field measurements are done. In order to check these data and to use them for geoid model determination DFHRS (Digital Finite element Height reference surface (HRS)) v4.3. software is used. It is based on parametric modelling of the HRS as a continous polynomial surface. The HRS, providing the local Geoid height N, is a necessary geodetic infrastructure for a GNSS-based determination of physcial heights H from ellipsoidal GNSS heights h, by H=h-N. The research and this publication is dealing with the inclusion of the data of observed vertical deflections from digital zenith camera into the mathematical model of the DFHRS approach and software v4.3. A first target was to test out and validate the mathematical model and software, using additionally real data of the above mentioned zenith camera observations of deflections of the vertical. A second concern of the research was to analyze the results and the improvement of the Latvian quasi-geoid computation compared to the previous version HRS computed without zenith camera based deflections of the vertical. The further development of the mathematical model and software concerns the use of spherical-cap-harmonics as the designed carrier function for the DFHRS v.5. It enables - in the sense of the strict integrated geodesy approach, holding also for geodetic network adjustment - both a full gravity field and a geoid and quasi-geoid determination. In addition, it allows the inclusion of gravimetric measurements, together with deflections of the vertical from digital-zenith cameras, and all other types of observations. The theoretical description of the updated version of DFHRS software and methods are discussed in this publication.

Design of a crystalline undulator based on patterning by tensile Si3N4 strips on a Si crystal

International Nuclear Information System (INIS)

Guidi, V.; Lanzoni, L.; Mazzolari, A.; Martinelli, G.; Tralli, A.

2007-01-01

A crystalline undulator consists of a crystal with a periodic deformation in which channeled particles undergo oscillations and emit coherent undulator radiation. Patterning by an alternate series of tensile Si 3 N 4 strips on a Si crystal is shown to be a tractable method to construct a crystalline undulator. The method allows periodic deformation of the crystal with the parameters suitable for implementation of a crystalline undulator. The resulting periodic deformation is present in the bulk of the Si crystal with an essentially uniform amplitude, making the entire volume of the crystal available for channeling and in turn for emission of undulator radiation

Measurement of position and profile of undulator radiation in Indus-2 using scanning wire monitor

International Nuclear Information System (INIS)

Kant, Chander; Lal, Sohan; Raghuwanshi, V.K.; Prasad, Vijendra

2015-01-01

Two planar undulators (U1 and U2) for Atomic Molecular Spectroscopy (AMOS) beamline and Angle Resolved Photoelectron Spectroscopy (ARPES) beamline have been installed in Indus-2. The U1 undulator is designed to produce photons in the energy range of 6 eV to 250 eV and U2 undulator is designed to produce photons in the energy range of 30 eV to 600 eV. In order to measure the position and vertical profile of photon beams emitted from these undulators, one scanning wire monitor has been installed in each beamline front end. In these scanning wire monitors, a gold coated tungsten wire of 100 μm thickness, stretched between a fork shaped alumina ceramic holder, is scanned vertically perpendicular to the direction of propagation of photon beam by using a precisely controlled stepper motor. The photo-electron current generated in the wire is measured by an electrometer. A graphical user interface has been developed which facilitates the scanning as per the given range, plots the graphs and stores the scanned data in Excel file. This paper describes our experience and usefulness of these wire monitors during commissioning of planar undulators in Indus-2. (author)

Brightness and coherence of radiation from undulators and high-gain free electron lasers

International Nuclear Information System (INIS)

Kim, Kwang-Je.

1987-03-01

The purpose of this paper is to review the radiation characteristics of undulators and high-gain free electron lasers (FELs). The topics covered are: a phase-space method in wave optics and synchrotron radiation, coherence from the phase-space point of view, discussions of undulator performances in next-generation synchrotron radiation facility and the characteristics of the high-gain FELs and their performances

Fabrication of mm-wave undulator cavities using deep x-ray lithography

International Nuclear Information System (INIS)

Song, J.; Feinerman, A.; Kang, Y.; Kustom, R.; Lai, B.; Nassiri, A.; White, V.; Well, G.M.

1996-01-01

The possibility of fabricating mm-wave radio frequency cavities (100 endash 300 GHz) using deep x-ray lithography (DXRL) is being investigated. The fabrication process includes manufacture of precision x-ray masks, exposure of positive resist by x-ray through the mask, resist development, and electroforming of the final microstructure. Highly precise, two-dimensional features can be machined onto wafers using DXRL. Major challenges are: fabrication of the wafers into three-dimensional rf structures; alignment and overlay accuracy of structures; adhesion of the PMMA on the copper substrate; and selection of a developer to obtain high resolution. Rectangular cavity geometry is best suited to this fabrication technique. A 30- or 84-cell 108-GHz mm-wave structure can serve as an electromagnetic undulator. A mm-wave undulator, which will be discussed later, may have special features compared to the conventional undulator. First harmonic undulator radiation at 5.2 keV would be possible using the Advanced Photon Source (APS) linac system, which provides a low-emittance electron beam by using an rf thermionic gun with an energy as high as 750 MeV. More detailed rf simulation, heat extraction analysis, beam dynamics using a mm-wave structure, and measurements on 10x larger scale models can be found in these proceedings [Y.W. Kang et al., open-quote open-quote Design and Construction of Planar mm-wave Accelerating Cavity Structures close-quote close-quote] copyright 1996 American Institute of Physics

Design and test of a trial undulator for a compact FEL THz radiation source

International Nuclear Information System (INIS)

Xiang Shuhua; Xiong Yongqian; Yang Lei; Liu Xialing; Wei Wei; Chen Jinhua

2012-01-01

The undulator is the key component in the THz radiation source based on FEL. We created a trial undulator in order to verify the feasibility of property requirements, and the accumulation of engineering experience. With the use of the finite element calculation software OPERA3D, we modify the structural parameters of the undulator gradually to meet the requirements of the peak, width of the good field and first integration. We also proved that the correction magnet could make the field meet the requirement of the second integration by calculation. After fabrication and acceptance, the electron trajectory is calculated based on the measured field. (authors)

Modeling and designing of variable-period and variable-pole-number undulator

Directory of Open Access Journals (Sweden)

I. Davidyuk

2016-02-01

Full Text Available The concept of permanent-magnet variable-period undulator (VPU was proposed several years ago and has found few implementations so far. The VPUs have some advantages as compared with conventional undulators, e.g., a wider range of radiation wavelength tuning and the option to increase the number of poles for shorter periods. Both these advantages will be realized in the VPU under development now at Budker INP. In this paper, we present the results of 2D and 3D magnetic field simulations and discuss some design features of this VPU.

Laser-driven soft-X-ray undulator source

International Nuclear Information System (INIS)

Fuchs, Matthias

2010-01-01

The experimental results described in this thesis demonstrate the successful synergy between the research fields described above: the development of an undulator source driven by laser-plasma accelerated electron beams. First efforts in this new field have led to the production of radiation in the visible to infrared part of the electromagnetic spectrum [Schlenvoigt et al., 2008]. In contrast to these early achievements, the experiment described here shows the successful production of laser-driven undulator radiation in the soft-X-ray range with a remarkable reproducibility. The source produced tunable, collimated beams with a wavelength of ∝17 nm from a compact setup. Undulator spectra were detected in ∝70% of consecutive driver-laser shots, which is a remarkable reproducibility for a first proof-of-concept demonstration using ultra-high intensity laser systems. This can be attributed to a stable electron acceleration scheme as well as to the first application of miniature magnetic quadrupole lenses with laseraccelerated beams. The lenses significantly reduce the electron beam divergence and its angular shot-to-shot fluctuations The setup of this experiment is the foundation of potential university-laboratory-sized, highly-brilliant hard X-ray sources. By increasing the electron energy to about 1 GeV, X-ray pulses with an expected duration of ∝10 fs and a photon energy of 1 keV could be produced in an almost identical arrangement. It can also be used as a testbed for the development of a free-electron laser of significantly smaller dimension than facilities based on conventional accelerators [Gruener et al., 2007]. Such compact sources have the potential for application in many fields of science. In addition, these developments could lead to ideal sources for ultrafast pump-probe experiments due to the perfect synchronization of the X-ray beam to the driver laser. (orig.)

Laser-driven soft-X-ray undulator source

Energy Technology Data Exchange (ETDEWEB)

Fuchs, Matthias

2010-08-04

The experimental results described in this thesis demonstrate the successful synergy between the research fields described above: the development of an undulator source driven by laser-plasma accelerated electron beams. First efforts in this new field have led to the production of radiation in the visible to infrared part of the electromagnetic spectrum [Schlenvoigt et al., 2008]. In contrast to these early achievements, the experiment described here shows the successful production of laser-driven undulator radiation in the soft-X-ray range with a remarkable reproducibility. The source produced tunable, collimated beams with a wavelength of {proportional_to}17 nm from a compact setup. Undulator spectra were detected in {proportional_to}70% of consecutive driver-laser shots, which is a remarkable reproducibility for a first proof-of-concept demonstration using ultra-high intensity laser systems. This can be attributed to a stable electron acceleration scheme as well as to the first application of miniature magnetic quadrupole lenses with laseraccelerated beams. The lenses significantly reduce the electron beam divergence and its angular shot-to-shot fluctuations The setup of this experiment is the foundation of potential university-laboratory-sized, highly-brilliant hard X-ray sources. By increasing the electron energy to about 1 GeV, X-ray pulses with an expected duration of {proportional_to}10 fs and a photon energy of 1 keV could be produced in an almost identical arrangement. It can also be used as a testbed for the development of a free-electron laser of significantly smaller dimension than facilities based on conventional accelerators [Gruener et al., 2007]. Such compact sources have the potential for application in many fields of science. In addition, these developments could lead to ideal sources for ultrafast pump-probe experiments due to the perfect synchronization of the X-ray beam to the driver laser. (orig.)

Coastline undulations on the West Coast of Denmark: Offshore extent, relation to breaker bars and transported sediment volume

DEFF Research Database (Denmark)

Kærgaard, Kasper Hauberg; Fredsøe, Jørgen; Knudsen, Søren B.

2012-01-01

This paper deals with field measurements of undulations of the bottom bathymetry along an otherwise straight coast at the Danish West Coast. Two bathymetric datasets and two time series of wave measurements are used in order to determine the following properties: the offshore extent of shoreline...... with undulations on the depth contours between −5m and +2m relative to mean sea level. In the other data set, only undulations on the depth contours between −1m and +1m are well correlated with the shoreline undulations. The main difference in the wave climate between the two locations is the orientation...

Selection of the optimum magnet design for the International Linear Collider positron source helical undulator

Directory of Open Access Journals (Sweden)

D. J. Scott

2007-03-01

Full Text Available A comparison of possible undulator designs for the International Linear Collider positron source has resulted in a superconducting bifilar wire design being selected. After a comprehensive paper study and fabrication of the two preeminent designs, the superconducting undulator was chosen instead of the permanent magnet alternative. This was because of its superior performance in terms of magnetic field strength and quality, operational flexibility, risk of radiation damage, ease in achieving the required vacuum, and cost. The superconducting undulator design will now be developed into a complete system design for the full 200 m long magnet that is required.

Gelatinous fibers and variant secondary growth related to stem undulation and contraction in a monkey ladder vine, Bauhinia glabra (Fabaceae).

Science.gov (United States)

Fisher, Jack B; Blanco, Mario A

2014-04-01

Some of the most striking stem shapes occur in species of Bauhinia (Fabaceae) known as monkey ladder vines. Their mature stems are flattened and develop regular undulations. Although stems have variant (anomalous) secondary growth, the mechanism causing the undulations is unknown. We measured stem segments over time (20 mo), described stem development using light microscopy, and correlated the changes in stem shape with anatomy. Growing stems are initially straight and bear tendrils on short axillary branches. The inner secondary xylem has narrow vessels and lignified fibers. As stems age, they become flattened and increasingly undulated with the production of two lobes of outer secondary xylem (OX) with wide vessels and only gelatinous fibers (G-fibers). Similar G-fibers are present in the secondary phloem and the cortical sclerified layer. In transverse sections, the concave side of each undulation has a greater area and quantity of G-fibers than the opposite convex side. Some older stems are not undulated and have less lobing of OX. Undulation causes a shortening of the stem segments: up to 28% of the original length. Uneven distribution of G-fibers produces tensions that are involved in the protracted development of undulations. While young extending shoots attach by lateral branch tendrils, older stems may maintain their position in the canopy using undulations and persistent branch bases as gripping devices. Flattened and undulated stems with G-fibers produce flexible woody stems.

Absolute measurement of undulator radiation in the extreme ultraviolet

International Nuclear Information System (INIS)

Maezawa, H.; Kitamura, H.; Sasaki, T.; Mitani, S.; Osaka City Univ.; Suzuki, Y.; Kanamori, H.; Tamamushi, S.; Tokyo Univ.; Mikuni, A.; Tokyo Univ., Tanashi

1983-01-01

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 #betta#, the field parameter K, and the angle of observation THETA 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 lambdasub(n)=lambda 0 /2n#betta# 2 (1+K 2 /2+#betta# 2 THETA 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. (orig.)

The APS x-ray undulator photon beam position monitor and tests at CHESS and NSLS

International Nuclear Information System (INIS)

Shu, D.; Rodricks, B.; Barraza, J.; Sanchez, T.; Kuzay, T.M.

1992-01-01

The advent of third generation synchrotron radiation sources, like the Advanced Photon Source (APS), will provide significant increases in brilliance over existing synchrotron sources. The APS x-ray undulators will increase the brilliance in the 3-40 KeV range by several orders of magnitude. Thus, the design of the photon beam position monitor is a challenging engineering task. The beam position monitors must withstand the high thermal load, be able to achieve sub-micron spatial resolution while maintaining their stability, and be compatible with both undulators and wigglers. A preliminary APS prototype photon beam position monitor consisting of a CVD-diamond-based, tungsten-coated blade was tested on the APS/CHESS undulator at the Cornell High Energy Synchrotron Radiation Source (CHESS) and on the NSLS X-13 undulator beamline. Results from these tests, as well as the design of this prototype APS photon beam position monitor, will be discussed in this paper

The APS X-ray undulator photon beam position monitor and tests at CHESS and NSLS

International Nuclear Information System (INIS)

Shu, D.; Rodricks, B.; Barraza, J.; Sanchez, T.; Kuzay, T.M.

1992-01-01

The advent of thirs generation synchrotron sources, like the Advanced Photon Source (APS), will provide significant increases in brilliance over existing synchrotron sources. The APS X-ray undulators will increase the brilliance in the 3-40 keV range by several orders of magnitude. Thus, the design of the photon beam position monitor is a challenging engineering task. The beam position monitors must withstand the high thermal load, be able to achieve submicron spatial resolution while maintaining their stability, and be compatible with both undulators and wigglers. A preliminary APS prototype photon beam position monitor consisting of a CVD-diamond-based, tungsten-coated blade was tested on the APS/CHESS undulator at the Cornell High Energy Synchrotron Radiation Source (CHESS) and on the NSLS X-13 undulator beamline. Results from these tests, as well as the design of this prototype APS photon beam position monitor, will be discussed in this paper. (orig.)

UHV testing of vacuum components and diagnostic devices, related to installation of Undulators in Indus-2

International Nuclear Information System (INIS)

Ratnakala, K.C.; Tiwari, S.K.; Bhange, N.J.; Yadav, D.P.; Babbar, L.K.; Netram; Sridhar, R.

2015-01-01

Two Insertion Devices, both planar Undulators (U1 and U2), have been successfully installed and commissioned in Indus-2, in Raja Ramanna Centre for Advanced Technology, Indore. The radiation from these Undulators are expected to be 2 to 3 orders of magnitude brighter than the radiation from the Bending Magnets. As required for the installation of these Insertion Devices in Indus-2 ring, two vacuum sections (LS 2 and LS 3) were modified. Apart from the main Undulator chambers (which were procured from the Manufacturer), several other components were developed in UHVT Section and Beam Diagnostic Section, for this purpose. The components include Taper chambers, Beam Position Indicators (both Insertion Device BPI-s and Upgraded BPI-s) and RF shielded bellows.Taper chambers were needed for the smooth transition of cross-section of vacuum envelope, from the normal straight section chamber (with dimensions: 36 mm x 86 mm) to the Undulator chamber (with dimensions: 17 mm x 81 mm). These chambers were required at both entry and exit of Undulator chambers. IDBPI-s and Upgraded BPI-s were needed for the precise monitoring of electron beam position, before the entry into the Undulator and after exiting the Undulator, at various critical positions. Bellows were required to be connected at various positions, during the assembly of vacuum chambers, for the mechanical flexibility. RF shielding was mandatory inside these bellows, to provide a smooth contour of the vacuum envelope, inside these bellows. All these components were tested in the UHV Lab, and confirmed for their UHV compatibility, prior to the actual assembly in the ring. Afterwards, these components were successfully installed in Indus-2 ring, by December, 2014. This paper narrates the UHV-tests carried out, including the assembly, leak-testing, baking, pumping etc. and the results. (author)

Variable Gap Undulator for 1.5-48 Kev Free Electron Laser at Linac Coherent Light Source

International Nuclear Information System (INIS)

2011-01-01

We study the feasibility of generating femtosecond duration Free-Electron Laser with a variable photon energy from 1.5 to 48 keV, using an electron bunch with the same characteristics of the LINAC Coherent Light Source (LCLS) bunch, and a planar undulator with additional focusing. We assume that the electron bunch energy can be changed, and the undulator has a variable gap, allowing a variable undulator parameter. It is assumed to be operated in an ultra-low charge and ultra-short pulse regime. We study the feasibility of a tunable, short pulse, X-ray FEL with photon energy from 1.5 to 48 keV, using an electron beam like the one in the LCLS and a 2:5 cm period, variable gap, planar undulator. The beam energy changes from 4.6 to 13.8 GeV, the electorn charge is kept at 10 pC, and the undulator parameter varies from 1 to 3. The undulator length needed to saturate the 48 keV FEL is about 55 m, with a peak power around 5 GW. At longer wavelength the saturation length is as short as 15 m, and the peak power around 20 GW. The results from the analytical models and the GENESIS simulations show that the system is feasible. The large wavelength range, full tunability and short, few femtosecond pulses, together with the large peak power, would provide a powerful research tool.

A hybrid type undulator for far-infrared FELs at FELI

Energy Technology Data Exchange (ETDEWEB)

Zako, A.; Miyauchi, Y.; Koga, A. [Free Electron Laser Research Institute, Inc., Osaka (Japan)] [and others

1995-12-31

Two FEL facilities of the FELI are now operating in the wavelength range of 1-20 {mu}m. A 3.2-m hybrid type undulator ({lambda}{sub u}=80mm, N=40) has been designed for far-infrared FELs and will be installed in December. It can cover the wavelength of 20-60 {mu}m by changing K-value from 1 to 2.7 for a 28.0-MeV electron beam. It is composed of ferrite magnetic poles and Sm-Co permanent magnets. Commonly wound coils induce alternating magnetic field in ferrite poles. Combination of the induced field and the permanent magnet field can controls the magnetic field between the undulator gap.

Small-gap undulator experiment on the NSLS X-ray Ring

International Nuclear Information System (INIS)

Stefan, P.M.; Krinsky, S.; Rakowsky, G.; Solomon, L.

1995-01-01

We report results of an on-going experiment being carried out in the X13 straight section of the NSLS X-ray Ring which explores the limits of the operation of small-gap undulators. In particular, we discuss measurements of stored electron beam lifetime as a function of the vertical aperture presented by a 4-jaw scraper or a variable-aperture vacuum vessel. At an electron beam current of 300 mA the variable-aperture vacuum chamber was closed to an inner aperture of 3.8 mm with no effect on the electron beam lifetime. Measurements of the output radiation spectrum of a 16 mm period undulator at a magnet gap of 7.5 mm are also described

Geoid modeling in Mexico and the collaboration with Central America and the Caribbean.

Science.gov (United States)

Avalos, D.; Gomez, R.

2012-12-01

The model of geoidal heights for Mexico, named GGM10, is presented as a geodetic tool to support vertical positioning in the context of regional height system unification. It is a purely gravimetric solution computed by the Stokes-Helmert technique in resolution of 2.5 arc minutes. This product from the Instituto Nacional de Estadistica y Geografia (INEGI) is released together with a series of 10 gravimetric models which add to the improvements in description of the gravity field. In the recent years, the INEGI joined the initiative of the U.S. National Geodetic Survey and the Canada's Geodetic Survey Division to promote the regional height system unification. In an effort to further improve the compatibility among national geoid models in the region, the INEGI has begun to champion a network of specialists that includes national representatives from Central America and the Caribbean. Through the opening of opportunities for training and more direct access to international agreements and discussions, the tropical region is gaining participation. Now a significantly increased number of countries is pushing for a future North and Central American geoid-based vertical datum as support of height system unification.eoidal height in Mexico, mapped from the model GGM10.

The U5.0 Undulator for the ALS

International Nuclear Information System (INIS)

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1991-05-01

The U5.0 Undulator, an 89 period, 5 cm period length, 4.6 m long insertion device has been designed and is in fabrication. This undulator will be the first high brightness source, in the 50 to 1500 eV range, for the Advanced Light Source (ALS) and is scheduled for completion in 1992. A modular hybrid configuration utilizing Nd-Fe-B permanent magnet material and vanadium permendur is used that achieves 0.837 Tesla effective peak field. Correction of the vertical field integral is with permanent magnet rotors at the ends. Gap adjustment is with an arrangement of roller screws, chains drives, a gear reduction unit and a stepper motor driven by a closed loop control system. The vacuum chamber design is a two-piece, machined and welded 5083-H321 aluminum construction of 5.1 m length. Magnetic design, subsystem design and fabrication progress are presented. 12 refs., 4 figs., 2 tabs

Longitudinal impedance and wake from XFEL undulators. Impact on current-enhanced SASE schemes

Energy Technology Data Exchange (ETDEWEB)

Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

2007-06-15

In this article we derive longitudinal impedance and wake function for an undulator setup with arbitrary undulator parameter, taking into account a finite transverse size of the electron bunch. Earlier studies considered a line density-distribution of electrons instead. We focus our attention on the long-wavelength asymptote (compared with resonance wavelength), at large distance of the electron bunch from the undulator entrance compared to the overtaking length, and for large vacuumchamber size compared to the typical transverse size of the field. These restrictions define a parameter region of interest for practical applications. We calculate a closed expression for impedance and wake function that may be evaluated numerically in the most general case. Such expression allows us to derive an analytical solution for a Gaussian transverse and longitudinal bunch shape. Finally, we study the feasibility of current-enhanced SASE schemes (ESASE) recently proposed for LCLS, that fall well-within our approximations. Numerical estimations presented in this paper indicate that impedance-induced energy spread is sufficient to seriously degrade the FEL performance. Our conclusion is in contrast with results in literature, where wake calculations for the LCLS case are given in free-space, as if the presence of the undulator were negligible. (orig.)

Active and passive compensation of APPLE II-introduced multipole errors through beam-based measurement

Energy Technology Data Exchange (ETDEWEB)

Chung, Ting-Yi; Huang, Szu-Jung; Fu, Huang-Wen; Chang, Ho-Ping; Chang, Cheng-Hsiang [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Hwang, Ching-Shiang [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Department of Electrophysics, National Chiao Tung University, Hsinchu 30050, Taiwan (China)

2016-08-01

The effect of an APPLE II-type elliptically polarized undulator (EPU) on the beam dynamics were investigated using active and passive methods. To reduce the tune shift and improve the injection efficiency, dynamic multipole errors were compensated using L-shaped iron shims, which resulted in stable top-up operation for a minimum gap. The skew quadrupole error was compensated using a multipole corrector, which was located downstream of the EPU for minimizing betatron coupling, and it ensured the enhancement of the synchrotron radiation brightness. The investigation methods, a numerical simulation algorithm, a multipole error correction method, and the beam-based measurement results are discussed.

Prototype photon position monitors for undulator beams at the advanced light source

International Nuclear Information System (INIS)

Warwick, T.; Shu, D.; Rodricks, B.; Johnson, E.D.

1992-01-01

Design criteria are described, and test results are presented, for prototype ALS undulator beam position monitors. The design is based on monitors presently in use at NSLS, with modifications to account for the widely varying and large K values of the undulators to be installed at the ALS. In particular, we have modified the design to simplify the thermal engineering and we have explored techniques to suppress the response of the monitors to soft photons, so that the beam position can be determined by measuring the higher energy photons which are better collimated

New implementation of an SX700 undulator beamline at the Advanced Light Source

International Nuclear Information System (INIS)

Warwick, T.; Andresen, N.; Comins, J.; Kaznacheyev, K.; Kortright, J.B.; McKean, P.J.; Padmore, H.A.; Shuh, D.K.; Stevens, T.; Tyliszczak, T.

2004-01-01

A newly engineered implementation of a collimated SX700-style beam line for soft x-rays is described. This facility is operational at the Advanced Light Source and delivers high brightness undulator beams to a scanning zone plate microscope and to an array of end stations for x-ray spectroscopic studies of wet surfaces. Switching between branches is motorized, servo-steering systems maintain throughput and the monochromator works together with the elliptical undulator for a fully automated facility

Empirical optimization of undulator tapering at FLASH2 and comparison with numerical simulations

Energy Technology Data Exchange (ETDEWEB)

Mak, Alan; Curbis, Francesca; Werin, Sverker [Lund Univ. (Sweden). MAX IV Laboratory; Faatz, Bart [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2016-08-15

In a free-electron laser equipped with variable-gap undulator modules, the technique of undulator tapering opens up the possibility to increase the radiation power beyond the initial saturation point, thus enhancing the efficiency of the laser. The effectiveness of the enhancement relies on the proper optimization of the taper profile. In this work, a multidimensional optimization approach is implemented empirically in the X-ray free-electron laser FLASH2. The empirical results are compared with numerical simulations.

Polarization Property Measurement of the Long Undulator Radiation Using Cr/C Multilayer Polarization Elements

International Nuclear Information System (INIS)

Niibe, Masahito; Mukai, Mikihito; Shoji, Yoshihiko; Kimura, Hiroaki

2004-01-01

A rotating analyzer ellipsometry (RAE) system was developed with Cr/C multilayers that function as polarization elements for photon energy range of 110 - 280 eV. Polarization properties of a planar undulator change axisymmetrically in off-axial manner, and the second harmonic is more remarkable for the change. By using the RAE system, the polarization property of the second harmonic radiation from the NewSUBARU long undulator at the energy of 180 eV was examined. The degree of linear polarization of the on-axis radiation was over 0.996. The spatial distribution of the polarization azimuth was measured and was in fair agreement with the theoretical calculation. A peculiar behavior of the polarization property near the radiation peak of the second harmonic was observed by changing the height of the undulator gap

Modelación del geoide en presas de colas de la región minera de Moa

Directory of Open Access Journals (Sweden)

Yordanis Esteban Batista-Legrá

2014-12-01

Full Text Available El presente trabajo tuvo el propósito de determinar el modelo del geoide en las presas de colas de la región minera de Moa, con el fin de obtener las alturas de puntos sobre la superficie del terreno con la exactitud que requiere el movimiento de tierras, para lo cual fueron empleados los Sistemas de Posicionamiento Global (GPS. Se aplicaron métodos de Topografía Minera, Geodesia Física, Hidrografía, Oceanografía, Cartografía Digital y Modelación y se integraron diferentes softwares para procesar la información obtenida en los experimentos. Como resultado se ofrece un nuevo método para determinar el modelo del geoide, la implementación de un Sistema de Información Geográfica (SIG para la modelación y un estudio del nivel medio del mar en la costa de Moa

Arctic Ocean gravity, geoid and sea-ice freeboard heights from ICESat and GRACE

DEFF Research Database (Denmark)

Forsberg, René; Skourup, Henriette

2005-01-01

Gravity Project in combination with GRACE gravity field models to derive an improved Arctic geoid model. This model is then used to convert ICESat measurements to sea-ice freeboard heights with a coarse lowest-level surface method. The derived freeboard heights show a good qualitative agreement...... all major tectonic features of the Arctic Ocean, and has an accuracy of 6 mGal compared to recent airborne gravity data, illustrating the usefulness of ICESat data for gravity field determination....

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

Science.gov (United States)

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.

Modulated electron bunch with amplitude front tilt in an undulator

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2015-12-01

In a previous paper we discussed the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. We demonstrated that the effect of aberration of light supplies the basis for understanding phenomena like the deflection of coherent undulator radiation by a dipole magnet. We illustrated this fact by examining the operation of an XFEL under the steady state assumption, that is a harmonic time dependence. We argued that in this particular case the microbunch front tilt has no objective meaning; in other words, there is no experiment that can discriminate whether an electron beam is endowed with a microbunch front tilt of not. In this paper we extend our considerations to time-dependent phenomena related with a finite electron bunch duration, or SASE mode of operation. We focus our attention on the spatiotemporal distortions of an X-ray pulse. Spatiotemporal coupling arises naturally in coherent undulator radiation behind the kick, because the deflection process involves the introduction of a tilt of the bunch profile. This tilt of the bunch profile leads to radiation pulse front tilt, which is equivalent to angular dispersion of the output radiation. We remark that our exact results can potentially be useful to developers of new generation XFEL codes for cross-checking their results.

Comparisons of geoid models over Alaska computed with different Stokes' kernel modifications

Science.gov (United States)

Li, X.; Wang, Y.

2011-01-01

Various Stokes kernel modification methods have been developed over the years. The goal of this paper is to test the most commonly used Stokes kernel modifications numerically by using Alaska as a test area and EGM08 as a reference model. The tests show that some methods are more sensitive than others to the integration cap sizes. For instance, using the methods of Vaníček and Kleusberg or Featherstone et al. with kernel modification at degree 60, the geoid decreases by 30 cm (on average) when the cap size increases from 1° to 25°. The corresponding changes in the methods of Wong and Gore and Heck and Grüninger are only at the 1 cm level. At high modification degrees, above 360, the methods of Vaníček and Kleusberg and Featherstone et al become unstable because of numerical problems in the modification coefficients; similar conclusions have been reported by Featherstone (2003). In contrast, the methods of Wong and Gore, Heck and Grüninger and the least-squares spectral combination are stable at any modification degree, though they do not provide as good fit as the best case of the Molodenskii-type methods at the GPS/Leveling benchmarks. However, certain tests for choosing the cap size and modification degree have to be performed in advance to avoid abrupt mean geoid changes if the latter methods are applied.

Triggering for Magnetic Field Measurements of the LCLS Undulators

Energy Technology Data Exchange (ETDEWEB)

Hacker, Kirsten

2010-12-13

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.

Triggering for Magnetic Field Measurements of the LCLS Undulators

International Nuclear Information System (INIS)

Hacker, Kirsten

2010-01-01

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.

Calculation of magnetic error fields in hybrid insertion devices

International Nuclear Information System (INIS)

Savoy, R.; Halbach, K.; Hassenzahl, W.; Hoyer, E.; Humphries, D.; Kincaid, B.

1989-08-01

The Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory requires insertion devices with fields sufficiently accurate to take advantage of the small emittance of the ALS electron beam. To maintain the spectral performance of the synchrotron radiation and to limit steering effects on the electron beam these errors must be smaller than 0.25%. This paper develops a procedure for calculating the steering error due to misalignment of the easy axis of the permanent magnet material. The procedure is based on a three dimensional theory of the design of hybrid insertion devices developed by one of us. The acceptable tolerance for easy axis misalignment is found for a 5 cm period undulator proposed for the ALS. 11 refs., 5 figs

Textured dysprosium and gadolinium poles for high-field, short-period hybrid undulators

International Nuclear Information System (INIS)

Murokh, Alex; Solovyov, Vyacheslav; Agustsson, Ron; O'Shea, Finn H.; Chubar, Oleg; Chen, Yung; Grandsaert, Thomas

2014-01-01

We discuss the feasibility of enhancement of the gap field in a short-period hybrid undulator by using pole inserts with the saturation inductance B s , over that of iron, 2 T. Dysprosium metal, with the saturation inductance of 3.4 T below 90 K, and Gadolinium with B s =2.7 T, appear as good candidates as the optimized pole material. However, due to the high magnetic anisotropy of Dy, such a high level of magnetization can only be realized when the external field lies in the basal plane. This implies that the pole has to be single-crystalline or highly textured. Considering that growing large, >10mm, Dy single crystals is difficult, we propose secondary recrystallization as a method to induce the required texture in thin Dy and Gd foils. The textured foils can be stacked to produce pole inserts of the desired geometry and orientation. Results of small-scale processing and magnetic measurements of thin (20–60 μ) foils provide evidence that the required texture quality can be achieved by a relatively simple sequence of heat-treatments and cold rolling. The advantage of textured Dy and Gd poles is demonstrated in a several period test undulator. -- Highlights: • Textured rare-earth materials for use as undulator pole materials. • We measure the development of texture in Dy and Gd. • We compare the rare-earth materials with high saturation steel in undulators. • Thin sheets of Dy and Gd materials perform similar to single crystals

The U5.0 Undulator for the ALS

International Nuclear Information System (INIS)

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1991-01-01

the U5.0 Undulator, and 89 period, 5 cm period length, 4.6 m long insertion device has been designed, is being fabricated and is scheduled for completion in early 1992. This undulator will be the first high brightness source, in the 50 to 1500 eV range, for the Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory. A hybrid magnetic configuration using Nd-Fe-B permanent magnet material and vanadium permendur poles has been selected to achieve the field quality needed to meet performance requirements. The magnetic structure is modular with each half consisting of 5 assembly sections, which provide the periodic structure, and end structures, for entrance and exit correction, mounted on a steel backing beam. Each assembly section consists of 35 half-period pole assemblies bolted to a mount. The required 0.837 Tesla effective peak field at a 1.4 cm gap has been verified with model measurements. Vertical field integral correction is accomplished with the end structures, each having an arrangement of permanent magnet rotors which will be adjusted to minimize electron beam missteering over the undulator operating field range. To reduce the effect of environmental fields, the steel backing beams are connected through parallel, low-reluctance, Ni-Fe hinges. The magnetic structure is connected through four roller-nuts to the drive system that provides gap adjustment with an arrangement of roller screws, chain drives, a gear reduction unit and a stepper motor driven by a closed loop control system. Magnetic structure and drive system support are from a 2.4 m high structure which includes a support base with four vertical supports. The vacuum chamber design is a two-piece machined and welded 5083-H321 aluminum construction of 5.1 m length. Pumping is with a combination of ion, TSP and NEG pumps. Magnetic design, subsystem design and fabrication progress are presented

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

Energy Technology Data Exchange (ETDEWEB)

Balal, N.; Magory, E. [Ariel University, Ariel 40700 (Israel); Bandurkin, I. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Bratman, V. L. [Ariel University, Ariel 40700 (Israel); Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950 (Russian Federation)

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 is 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.

Operation of a small-gap undulator on the NSLS X-ray Ring

Energy Technology Data Exchange (ETDEWEB)

Stefan, P.M.; Krinsky, S.; Rakowsky, G.; Solomon, L. [Brookhaven National Lab., Upton, NY (United States)

1995-02-01

The authors report results of an on-going experiment being carried out in the X13 straight section of the NSLS X-ray Ring which explores the limits of the operation of small-gap undulators. In particular, they discuss the operation of a 16 mm period small-gap undulator. At an electron beam current of 300 mA the variable gap vacuum chamber has been closed to an inner aperture of 3.8 mm with no effect on the electron beam lifetime. Measurements of the output radiation spectrum at a magnet gap of 7.5 mm are described.

Magnetic design of a 14 mm period prototype superconducting undulator

Energy Technology Data Exchange (ETDEWEB)

Gehlot, Mona, E-mail: mona_gehlot@yahoo.com [Insertion Device Development Laboratory, School of Physics, Devi Ahilya University, Indore 452001, MP (India); Mishra, G. [Insertion Device Development Laboratory, School of Physics, Devi Ahilya University, Indore 452001, MP (India); Institute of Engineering, UNAM (Mexico); Soleil, Paris (France); Trillaud, Frederic [Institute of Engineering, UNAM (Mexico); Sharma, Geetanjali [Soleil, Paris (France)

2017-02-21

In this paper we report the design of a 14 mm period prototype superconducting undulator that is under fabrication at Insertion Device Development Laboratory (IDDL) at Devi Ahilya Vishwavidyalaya, Indore, India. The field computations are made in RADIA and results are presented in an analytical form for computation of the on axis field and the field on the surface of the coil. On the basis of the findings, a best fit is presented for the model to calculate the field dependence on the gap and the current density. The fit is compared with Moser-Rossmanith formula proposed earlier to predict the magnetic flux density of a superconducting undulator. The field mapping is used to calculate the field integrals and its dependence on gap and current densities as well.

Goce derived geoid changes before the Pisagua 2014 earthquake

Directory of Open Access Journals (Sweden)

Orlando Álvarez

2018-01-01

Full Text Available The analysis of space – time surface deformation during earthquakes reveals the variable state of stress that occurs at deep crustal levels, and this information can be used to better understand the seismic cycle. Understanding the possible mechanisms that produce earthquake precursors is a key issue for earthquake prediction. In the last years, modern geodesy can map the degree of seismic coupling during the interseismic period, as well as the coseismic and postseismic slip for great earthquakes along subduction zones. Earthquakes usually occur due to mass transfer and consequent gravity variations, where these changes have been monitored for intraplate earthquakes by means of terrestrial gravity measurements. When stresses and correspondent rupture areas are large, affecting hundreds of thousands of square kilometres (as occurs in some segments along plate interface zones, satellite gravimetry data become relevant. This is due to the higher spatial resolution of this type of data when compared to terrestrial data, and also due to their homogeneous precision and availability across the whole Earth. Satellite gravity missions as GOCE can map the Earth gravity field with unprecedented precision and resolution. We mapped geoid changes from two GOCE satellite models obtained by the direct approach, which combines data from other gravity missions as GRACE and LAGEOS regarding their best characteristics. The results show that the geoid height diminished from a year to five months before the main seismic event in the region where maximum slip occurred after the Pisagua Mw = 8.2 great megathrust earthquake. This diminution is interpreted as accelerated inland-directed interseismic mass transfer before the earthquake, coinciding with the intermediate degree of seismic coupling reported in the region. We highlight the advantage of satellite data for modelling surficial deformation related to pre-seismic displacements. This deformation, combined to

Design, development, installation and commissioning of water-cooled pre-masks for undulator front-ends of Indus-2

International Nuclear Information System (INIS)

Raghuvanshi, V.K.; Prasad, Vijendra; Garg, S.R.; Jain, Vikas

2015-01-01

Recently two undulators U1 and U2 are installed in Indus-2 storage ring at RRCAT, Indore. When U1 and U2 are put in operation, a bright synchrotron radiation (SR) is produced which is transmitted through the zero degree port of the dipole vacuum chamber. In addition, a part of SR beam from the bending magnets, at the upstream and downstream of the undulator, is also overlapped with the undulator SR beam and transmitted in to the front-end through the same port. The front-end is a long ultra high vacuum (UHV) assembly consisting of water-cooled pre-mask, water-cooled shutters, UHV valves, diagnostic devices, safety shutter, vacuum pumps etc which acts as an interface between Indus-2 ring and beamline. Water-cooled pre- masks have been designed to cut a part of unwanted SR beam from the bending magnets. The pre-mask is a first active component in the undulator front-end which is also capable of absorbing high thermal load due to mis-steering of the SR beam from the undulator in the worst case scenario. The watercooled pre-mask consists of a copper block which has fixed aperture with slant faces to distribute the heat flux over a large surface area. The cooling channels are made on outer periphery of the block. The copper block is vacuum brazed with two conflat flanges of stainless steel at the two ends. The pre-mask is designed to absorb thermal load of 3 kW of synchrotron beam from undulator U1 and 2 kW of synchrotron beam from undulator U2. The thermal analysis of the pre-masks was carried out with the help of ANSYS® and the design was optimized with different cooling configurations. The main design criteria was to limit the maximum temperature of the mask less than 60 °C. This is to avoid substantial thermal outgassing from the heated portion which may deteriorate the ultra high vacuum. Pre-masks have been successfully tested, installed and commissioned with synchrotron beam in the undulator front-ends and are operating under vacuum of 5x10 -10 mbar. (author)

Permanent magnets including undulators and wigglers

CERN Document Server

Bahrdt, J

2010-01-01

After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrates on the applications of permanent magnets in accelerators starting from dipoles and quadrupoles on to wigglers and undulators.

Design and implementation of VUV-CD and LD measurements using an ac modulated polarizing undulator

International Nuclear Information System (INIS)

Yagi-Watanabe, K.; Yamada, T.; Tanaka, M.; Kaneko, F.; Kitada, T.; Ohta, Y.; Nakagawa, K.

2005-01-01

VUV circular dichroism (CD) and linear dichroism (LD) have been successfully measured at wavelengths beyond the conventional limit by using an ac modulated polarizing undulator. We have developed CD and LD measuring technique by polarization modulation at the source, without using transmission type polarizing modulator, to extend to the coverage to wavelengths shorter than 140-bar nm. AIST developed in 1986 ac polarizing undulator by using a electron storage ring 'TERAS' based on an original concept. The undulator which can produce any desired polarization of vertical- and horizontal-linear polarization (VLP and HLP) and right- and left-handed circular polarization (RCP and LCP) is specially well suited to both measurements of CD and LD. With this undulator, the polarization alternate in the order of VLP-RCP-HLP-RCP-VLP-LCP-HLP-LCP-VLP-, i.e. when circular polarization is modulated in f Hz, linear polarization alters in 2f Hz. This allows us simultaneous measurements of CD and LD. Since the TERAS can produce ac-modulated polarized radiation of wavelength as short as 40-bar nm, it is expected to have CD and LD measurement extended to 40-bar nm

Obtaining high degree of circular polarization at X-ray FELs via a reverse undulator taper

Energy Technology Data Exchange (ETDEWEB)

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

2013-08-15

Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced. The proposed method is rather universal, i.e. it can be used at SASE FELs and seeded (self-seeded) FELs, with any wavelength of interest, in a wide range of electron beam parameters, and with any repetition rate. It can be used at different X-ray FEL facilities, in particular at LCLS after installation of the helical afterburner in the near future.

Effect of the drift gap between the undulator sections on the operation of the Fusion-FEM

NARCIS (Netherlands)

van der Geer, C. A. J.; Militsyn, B. L.; Bongers, W. A.; Bratman, V. L.; Denisov, G. G.; Manintveld, P.; Savilov, A. V.; Varfolomeev, A. A.; Verhoeven, A. G. A.; Urbanus, W. H.

2000-01-01

The 'Fusion-FEM' is a free electron MASER based on an electrostatic accelerator. An electron beam of 12 A, 1.35-2 MeV is injected into a step-tapered undulator to generate 1 MW of radiation in the range 130-250 GHz. The undulator is built from two sections with different field strength

Radial profiles of temperature and viscosity in the Earth's mantle inferred from the geoid and lateral seismic structure

NARCIS (Netherlands)

Cadek, O.; Berg, A.P. van den

1998-01-01

In the framework of dynamical modelling of the geoid, we have estimated basic features of the radial profile of temperature in the mantle. The applied parameterization of the geotherm directly characterizes thermal boundary layers and values of the thermal gradient in the upper and lower mantle.

Knot Undulator to Generate Linearly Polarized Photons with Low on-Axis Power Density

International Nuclear Information System (INIS)

Qiao, S.

2009-01-01

Heat load on beamline optics is a serious problem to generate pure linearly polarized photons in the third generation synchrotron radiation facilities. For permanent magnet undulators, this problem can be overcome by a figure-8 operating mode. But there is still no good method to tackle this problem for electromagnetic elliptical undulators. Here, a novel operating mode is suggested, which can generate pure linearly polarized photons with very low on-axis heat load. Also the available minimum photon energy of linearly polarized photons can be extended much by this method.

Generation of x-ray radiation in a storage ring by a superconductive cold-bore in-vacuum undulator

Directory of Open Access Journals (Sweden)

S. Casalbuoni

2006-01-01

Full Text Available The first beam measurements with a cold-bore superconducting in-vacuum undulator in a storage ring are reported. Undulators are x-ray generators in light sources. The physical limitations of these devices limit the intensity and the brilliance of the x-ray beam. At present the undulators are made from permanent magnets. It was shown in earlier papers that at low electron beam intensities superconductive wires in the vacuum beam pipe can overcome the limitations inherent to permanent magnet undulators. It was argued that the use of these novel devices in light sources with high beam currents may be limited by the extreme anomalous skin effect regime in Cu at 4.2 K, which has so far undergone very little investigation, and the power deposited by the infrared part of the synchrotron radiation. The purpose of this paper is to present measurements of these effects at the synchrotron light source ANKA with stored currents up to 200 mA.

Optimal propulsion of an undulating slender body with anisotropic friction.

Science.gov (United States)

Darbois Texier, Baptiste; Ibarra, Alejandro; Melo, Francisco

2018-01-24

This study investigates theoretically and numerically the propulsive sliding of a slender body. The body sustains a transverse and propagative wave along its main axis, and undergoes anisotropic friction caused by its surface texture sliding on the floor. A model accounting for the anisotropy of frictional forces acting on the body is implemented. This describes the propulsive force and gives the optimal undulating parameters for efficient forward propulsion. The optimal wave characteristics are effectively compared to the undulating motion of a slithering snakes, as well as with the motion of sandfish lizards swimming through the sand. Furthermore, numerical simulations have indicated the existence of certain specialized segments along the body that are highly efficient for propulsion, explaining why snakes lift parts of their body while slithering. Finally, the inefficiency of slithering as a form of locomotion to ascend a slope is discussed.

Wakefields in the LCLS Undulator Transitions

Energy Technology Data Exchange (ETDEWEB)

Bane, K.L.F.; /SLAC; Zagorodov, I.; /DESY

2006-07-17

For a short bunch in an elliptical collimator we demonstrate that, as in a purely round collimator, the wake can be estimated from the primary fields of the beam alone. We obtain the wakes in the LCLS rectangular-to-round, undulator transitions using a hybrid method that includes indirect numerical (field) integration and an analytical potential energy term. For the LCLS 1 nC bunch charge configuration, we find the wake-induced energy change in the transitions to be small compared to that due to the resistance of the beam pipe walls.

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

Energy Technology Data Exchange (ETDEWEB)

Miyauchi, Hiroshi, E-mail: hiroshi.miyauchi@kek.jp [Accelerator Laboratory, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Department of Accelerator Science, School of High Energy Accelerator Science, SOKENDAI (The Graduate University for Advanced Studies), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Tahara, Toshihiro, E-mail: ttahara@post.kek.jp; Asaoka, Seiji, E-mail: seiji.asaoka@kek.jp [Accelerator Laboratory, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2016-07-27

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.

Electromagnetic design, implementation and test of a superconducting undulator with a transverse gradient field amplitude

Energy Technology Data Exchange (ETDEWEB)

Afonso Rodriguez, Veronica

2015-11-25

This thesis describes the development of a novel superconducting transversal gradient undulator (TGU) designed to form a compact, highly brilliant laser-wakefield accelerator (LWFA) driven radiation source. A TGU in combination with a dispersive beam transport line can be employed to produce undulator radiation with natural bandwidth despite the large energy spread of the LWFA. This thesis documents the construction, first tests and characterization of the full-scale TGU.

On the equivalence of spherical splines with least-squares collocation and Stokes's formula for regional geoid computation

Science.gov (United States)

Ophaug, Vegard; Gerlach, Christian

2017-11-01

This work is an investigation of three methods for regional geoid computation: Stokes's formula, least-squares collocation (LSC), and spherical radial base functions (RBFs) using the spline kernel (SK). It is a first attempt to compare the three methods theoretically and numerically in a unified framework. While Stokes integration and LSC may be regarded as classic methods for regional geoid computation, RBFs may still be regarded as a modern approach. All methods are theoretically equal when applied globally, and we therefore expect them to give comparable results in regional applications. However, it has been shown by de Min (Bull Géod 69:223-232, 1995. doi: 10.1007/BF00806734) that the equivalence of Stokes's formula and LSC does not hold in regional applications without modifying the cross-covariance function. In order to make all methods comparable in regional applications, the corresponding modification has been introduced also in the SK. Ultimately, we present numerical examples comparing Stokes's formula, LSC, and SKs in a closed-loop environment using synthetic noise-free data, to verify their equivalence. All agree on the millimeter level.

Combined electromagnetic and permanent magnet undulator to achieve higher field and easier field variation without mechanical movement

International Nuclear Information System (INIS)

Bogachenkov, V.A.; Papadichev, V.A.

1995-01-01

Hybrid or pure permanent magnet undulators (PMU) are widely used because they have high field quality, allow easy field correction and do not consume power. Their main drawback is the necessity of moving one half of the magnet relative to the other to change field value, which requires a high precision, remotely controlled (and thus costly) driving system On the other hand, electromagnetic undulatory (EMU) have no problem with field variation, but consume too much power (100 - 400 kW) for high fields. Adding permanent magnets to EMU results in a considerable decrease of power consumption, while retaining the advantage of easily changing field level. A model of a CW combined EM+PM plane undulator having a 4.8 cm period and 8 periods long is described. It is simple in design and cheap in manufacturing: magnet yokes are made of soft steel rings in which 1.6 cm air gaps were cut to form pole faces. Odd yokes are placed to one side of the undulator axis and even yokes to the other with the air gaps on the axis. Each set of yokes is excited by its own separate winding of simple racetrack shape. Undulator deflection parameter K = 1.1 (B = 2.4 kG) can be reached at a 0.78kW power level, i.e., less than 100 W per period, while without PM only a maximum K = 0.8 can be obtained and requires 4 kW power. No water cooling is needed, which greatly simplifies undulator design. The undulator was not optimized relative to the axial-air-gap to ring-width ratio: one might expect some increase in field level for thinner rings. Field amplitude depends also on relative transverse position of odd and even pole faces

Combined electromagnetic and permanent magnet undulator to achieve higher field and easier field variation without mechanical movement

Energy Technology Data Exchange (ETDEWEB)

Bogachenkov, V.A.; Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

1995-12-31

Hybrid or pure permanent magnet undulators (PMU) are widely used because they have high field quality, allow easy field correction and do not consume power. Their main drawback is the necessity of moving one half of the magnet relative to the other to change field value, which requires a high precision, remotely controlled (and thus costly) driving system On the other hand, electromagnetic undulatory (EMU) have no problem with field variation, but consume too much power (100 - 400 kW) for high fields. Adding permanent magnets to EMU results in a considerable decrease of power consumption, while retaining the advantage of easily changing field level. A model of a CW combined EM+PM plane undulator having a 4.8 cm period and 8 periods long is described. It is simple in design and cheap in manufacturing: magnet yokes are made of soft steel rings in which 1.6 cm air gaps were cut to form pole faces. Odd yokes are placed to one side of the undulator axis and even yokes to the other with the air gaps on the axis. Each set of yokes is excited by its own separate winding of simple racetrack shape. Undulator deflection parameter K = 1.1 (B = 2.4 kG) can be reached at a 0.78kW power level, i.e., less than 100 W per period, while without PM only a maximum K = 0.8 can be obtained and requires 4 kW power. No water cooling is needed, which greatly simplifies undulator design. The undulator was not optimized relative to the axial-air-gap to ring-width ratio: one might expect some increase in field level for thinner rings. Field amplitude depends also on relative transverse position of odd and even pole faces.

Peak Fields of Nb$_{3}$Sn Superconducting Undulators and a Scaling Law

CERN Document Server

Kim, S H

2005-01-01

The peak fields on the beam axis and the maximum fields in the conductor of Nb$_{3}$Sn superconducting undulators (SCUs) were calculated for an undulator period length of 16 mm. Using a simple scaling law for SCUs [1], the peak fields, as well as the conductor maximum fields and the current densities, were calculated for a period range of 8 to 32 mm. The critical current densities of commercially available Nb$_{3}$Sn superconducting strands were used for the calculations. The achievable peak fields are limited mainly by the flux-jump instabilities at low fields. The possible or feasible peak field will also be compared with that achieved in prototype development of SCUs.

Comparison of different undulator schemes with superimposed alternating gradients for the VUV-FEL at the TESLA Test Facility

Energy Technology Data Exchange (ETDEWEB)

Pflueger, J.; Nikitina, Y.M. [DESY/HASYLAB, Hamburg (Germany)

1995-12-31

For the VUV-FEL at the TESLA Test Facility an undulator with a total length of 30 m is needed. In this study three different approaches to realize an undulator with a sinusoidal plus a superimposed quadrupolar field were studied with the 3D code MAFIA.

The E166 experiment: Development of an undulator-based ...

Indian Academy of Sciences (India)

A longitudinal polarized positron beam is foreseen for the international linear collider (ILC). A proof-of-principle experiment has been performed in the final focus test beam at SLAC to demonstrate the production of polarized positrons for implementation at the ILC. The E166 experiment uses a 1 m long helical undulator in a ...

Scheme for Generation highly monochromatic X-Rays from a baseline XFEL undulator

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2010-03-01

One goal of XFEL facilities is the production of narrow bandwidth X-ray radiation. The self-seeding scheme was proposed to obtain a bandwidth narrower than that achievable with conventional X-ray SASE FELs. A self-seeded FEL is composed of two undulators separated by a monochromator and an electron beam bypass that must compensate for the path delay of X-rays in the monochromator. This leads to a long bypass, with a length in the order of 40-60 m, which requires modifications of the baseline undulator configuration. As an attempt to get around this obstacle, together with a study of the self-seeding scheme for the European XFEL, here we propose a novel technique based on a pulse doubler concept. Using a crystal monochromator installed within a short magnetic chicane in the baseline undulator, it is possible to decrease the bandwidth of the radiation well beyond the XFEL design down to 10 -5 . The magnetic chicane can be installed without any perturbation of the XFEL focusing structure, and does not interfere with the baseline mode of operation. We present a feasibility study and we make exemplifications with the parameters of the SASE2 line of the European XFEL. (orig.)

Ginzburg's invention of undulators and their role in modern synchrotron radiation sources and free electron lasers

International Nuclear Information System (INIS)

Kulipanov, Gennadii N

2007-01-01

Undulators - periodic magnetic structures that were originally introduced by Vitalii Ginzburg in 1947 for electromagnetic radiation generation using relativistic electrons - are among the key elements of modern synchrotron radiation sources and free electron lasers (FELs). In this talk, the history of three generations of storage ring-based synchrotron X-ray sources using wigglers and undulators is briefly traced. Prospects for two types of next-generation space-coherent X-ray sources are discussed, which use long undulators and energy recovery accelerators or, alternatively, employ linear accelerator-based FELs. The recently developed Novosibirsk terahertz FEL facility, currently the world' s most powerful terahertz source, is described. It was the generation of electromagnetic radiation in this range that Ginzburg discussed in his 1947 work. (oral issue of the journal 'uspekhi fizicheskikh nauk')

A rapid method to map the crustal and lithospheric thickness using elevation, geoid anomaly and thermal analysis. Application to the Gibraltar Arc System, Atlas Mountains and adjacent zones

Science.gov (United States)

Fullea, J.; Fernàndez, M.; Zeyen, H.; Vergés, J.

2007-02-01

We present a method based on the combination of elevation and geoid anomaly data together with thermal field to map crustal and lithospheric thickness. The main assumptions are local isostasy and a four-layered model composed of crust, lithospheric mantle, sea water and the asthenosphere. We consider a linear density gradient for the crust and a temperature dependent density for the lithospheric mantle. We perform sensitivity tests to evaluate the effect of the variation of the model parameters and the influence of RMS error of elevation and geoid anomaly databases. The application of this method to the Gibraltar Arc System, Atlas Mountains and adjacent zones reveals the presence of a lithospheric thinning zone, SW-NE oriented. This zone affects the High and Middle Atlas and extends from the Canary Islands to the eastern Alboran Basin and is probably linked with a similarly trending zone of thick lithosphere constituting the western Betics, eastern Rif, Rharb Basin, and Gulf of Cadiz. A number of different, even mutually opposite, geodynamic models have been proposed to explain the origin and evolution of the study area. Our results suggest that a plausible slab-retreating model should incorporate tear and asymmetric roll-back of the subducting slab to fit the present-day observed lithosphere geometry. In this context, the lithospheric thinning would be caused by lateral asthenospheric flow. An alternative mechanism responsible for lithospheric thinning is the presence of a hot magmatic reservoir derived from a deep ancient plume centred in the Canary Island, and extending as far as Central Europe.

Conceptual design of an undulator system for a dedicated bio-imaging beamline at the European X-ray FEL

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-05-15

We describe a future possible upgrade of the European XFEL consisting in the construction of an undulator beamline dedicated to life science experiments. The availability of free undulator tunnels at the European XFEL facility offers a unique opportunity to build a beamline optimized for coherent diffraction imaging of complex molecules, like proteins and other biologically interesting structures. Crucial parameters for such bio-imaging beamline are photon energy range, peak power, and pulse duration. Key component of the setup is the undulator source. The peak power is maximized in the photon energy range between 3 keV and 13 keV by the use of a very efficient combination of self-seeding, fresh bunch and tapered undulator techniques. The unique combination of ultra-high peak power of 1 TW in the entire energy range, and ultrashort pulse duration tunable from 2 fs to 10 fs, would allow for single shot coherent imaging of protein molecules with size larger than 10 nm. Also, the new beamline would enable imaging of large biological structures in the water window, between 0.3 keV and 0.4 keV. In order to make use of standardized components, at present we favor the use of SASE3-type undulator segments. The number segments, 40, is determined by the tapered length for the design output power of 1 TW. The present plan assumes the use of a nominal electron bunch with charge of 0.1 nC. Experiments will be performed without interference with the other three undulator beamlines. Therefore, the total amount of scheduled beam time per year is expected to be up to 4000 hours.

Advantage and Challenges of $Nb_3Sn$ Superconducting Undulators

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A. V. [Fermilab; Barzi, E. [Fermilab; Turrinoni, D. [Fermilab; Ivanyushenkov, Yu. [Argonne; Kesgin, I. [Argonne

2018-04-01

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.

Numerical modeling of shoreline undulations part 1: Constant wave climate

DEFF Research Database (Denmark)

Kærgaard, Kasper Hauberg; Fredsøe, Jørgen

2013-01-01

integrated flow model, a wave-phase resolving sediment transport description and a one-line shoreline model.First the length of the shoreline undulations is determined in the linear regime using a stability analysis. Next the further evolution from the linear to the fully non-linear regime is described...

Test of an undulated vacuum chamber for the ISR

CERN Multimedia

1975-01-01

This picture shows mechanical tests of an undulated vacuum chamber for downstream arms of ISR intersections. This chamber, made of 0.3 mm thick inconel, had inner dimensions of 150 mm by 50 mm. The deflection under vacuum is measured by dial gauges. On the left one sees the large vessel where vacuum chambers were tested at pressures above atmospheric pressure.

Purified SASE undulator configuration to enhance the performance of the soft x-ray beamline at the European XFEL

International Nuclear Information System (INIS)

Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor; Geloni, Gianluca

2013-08-01

The purified SASE (pSASE) undulator configuration recently proposed at SLAC promises an increase in the output spectral density of XFELs. In this article we study a straightforward implementation of this configuration for the soft x-ray beamline at the European XFEL. A few undulator cells, resonant at a subharmonic of the FEL radiation, are used in the middle of the exponential regime to amplify the radiation, while simultaneously reducing the FEL bandwidth. Based on start-to-end simulations, we show that with the proposed configuration the spectral density in the photon energy range between 1.3 keV and 3 keV can be enhanced of an order of magnitude compared to the baseline mode of operation. This option can be implemented into the tunable-gap SASE3 baseline undulator without additional hardware, and it is complementary to the self-seeding option with grating monochromator proposed for the same undulator line, which can cover the photon energy range between about 0.26 keV and 1 keV.

A new undulator for the extension of the spectral range of the CLIO FEL

Energy Technology Data Exchange (ETDEWEB)

Marcouille, O.; Berset, J.M.; Glotin, F. [LURE, Orsay (France)] [and others

1995-12-31

We built a new undulator in order to extend the lasing range of the CLIO infrared FEL. Presently, CLIO operates in the wavelength range 2 - 17 {mu}m. Beyond 14 {mu}m, the power decreases rapidly, because of the diffraction losses of the vacuum chamber (7 mm height and 2 m long). Thus, lasing at higher wavelengths implies installing a chamber with a height approximately twice. Then the minimum gap is increased and the maximum deflection parameter, K, is reduced from 2 to 1 : the laser tunability is greatly reduced. This is why a new undulator has been built.

Undulator based scanning microscope at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Rarback, H.; Shu, D.; Ade, H.; Jacobsen, C.; Kirz, J.; McNulty, I.; Rosser, R.

1986-01-01

A second generation scanning soft x-ray microscope is under construction, designed to utilize the dramatic increase in source bightness available at the soft x-ray undulator. The new instrument is expected to reduce image acquisition time by a factor of about 100, and to improve resolution, stability, and reproducibility

Numeric Simulation on the Performance of an Undulating Fin in the Wake of a Periodic Oscillating Plate

Directory of Open Access Journals (Sweden)

Zhang Yong-Hua

2013-10-01

Full Text Available A two-dimensional unsteady computational fluid dynamics (CFD method using an unstructured, grid-based and unsteady Navier-Stokes solver with automatic adaptive re-meshing to compute the unsteady flow was adopted to study the hydrodynamic interaction between a periodic oscillating plate and a rigid undulating fin in tandem arrangement. The user-defined function (UDF program was compiled to define the undulating and oscillating motion. First, the influence of the distance between the anterior oscillating plate and the posterior undulating fin on the non-dimensional drag coefficient of the fin was investigated. Ten different distances, D=0.2L, 0.4L, 0.6L, 0.8L, 1.0L, 1.2L, 1.4L, 1.6L, 1.8L and 2.0L, were considered. The performance of the fin for different distances (D is different. Second, the plate oscillating angle (5.7°, 10°, 20°, 30°, 40°, 45°, 50° and frequency (0.5 Hz, 1.0 Hz, 1.5 Hz, 2.0 Hz, 2.5 Hz, 3.0 Hz, 3.5 Hz, 4.0 Hz effects on the non-dimensional drag coefficient of the fin were also implemented. The pressure distribution on the fin was computed and integrated to provide fin forces, which were decomposed into lift and thrust. Meanwhile, the flow field was demonstrated and analysed. Based on the flow structures, the reasons for different undulating performances were discussed. It shows that the results largely depend on the distance between the two objects. The plate oscillating angle and frequency also make a certain contribution to the performance of the posterior undulating fin. The results are similar to the interaction between two undulating objects in tandem arrangement and they may provide a physical insight into the understanding of fin interaction in fishes or bio-robotic underwater propulsors that are propelled by multi fins.

X-ray absorption spectroscopy of diluted system by undulator photon source and multi-element solid-state detector

CERN Document Server

Tanida, H

2001-01-01

In order to measure the extended X-ray absorption fine structure (EXAFS) spectrum of an ultra-diluted system, an optics and detector control system for a synchrotron radiation beamline is developed. The undulator gap width is continuously tuned to obtain the maximum X-ray photon flux during the energy scan for the EXAFS measurement. A piezoelectric translator optimizes the parallelism of the double crystal in a monochromator at each measurement point to compensate for mechanical errors of the monochromator, resulting in a smooth and intense X-ray photon flux during the measurement. For a detection of a weak fluorescence signal from diluted samples, a 19-element solid-state detector and digital signal processor are used. A K-edge EXAFS spectrum of iron in a myoglobin aqueous solution with a concentration of 5.58 parts per million was obtained by this system.

New geoid of Greenland: A case study of terrain and ice effects, GOCE and use of local sea level data

DEFF Research Database (Denmark)

Forsberg, René; Jensen, Tim Enzlberger

2015-01-01

Making an accurate geoid model of Greenland has always been a challenge due to the ice sheet and glaciers, and the rough topography and deep fjords in the ice free parts. Terrestrial gravity coverage has for the same reasons been relatively sparse, with an older airborne survey of the interior be...

Mapping of sea bottom topography over western offshore, India using TOPEX/ERS-1 altimeter data

Digital Repository Service at National Institute of Oceanography (India)

Mohanty, K.K.; Majumdar, T.J.; Kunte, P.D.; Srivastava, A.K.

topography in SSH. Cross-over corrections are applied to account for the orbital error in the altimetric observation. The corrected SSH has been used as an approximation to the marine geoid. The bathymetry is related with the geoid through a convolution model...

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

Science.gov (United States)

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.

Gravity model development for TOPEX/POSEIDON: Joint gravity models 1 and 2

Science.gov (United States)

Nerem, R. S.; Lerch, F. J.; Marshall, J. A.; Pavlis, E. C.; Putney, B. H.; Tapley, B. D.; Eanes, R. J.; Ries, J. C.; Schutz, B. E.; Shum, C. K.

1994-01-01

The TOPEX/POSEIDON (T/P) prelaunch Joint Gravity Model-1 (JGM-1) and the postlaunch JGM-2 Earth gravitational models have been developed to support precision orbit determination for T/P. Each of these models is complete to degree 70 in spherical harmonics and was computed from a combination of satellite tracking data, satellite altimetry, and surface gravimetry. While improved orbit determination accuracies for T/P have driven the improvements in the models, the models are general in application and also provide an improved geoid for oceanographic computations. The postlaunch model, JGM-2, which includes T/P satellite laser ranging (SLR) and Doppler orbitography and radiopositioning integrated by satellite (DORIS) tracking data, introduces radial orbit errors for T/P that are only 2 cm RMS with the commission errors of the marine geoid for terms to degree 70 being +/- 25 cm. Errors in modeling the nonconservative forces acting on T/P increase the total radial errors to only 3-4 cm root mean square (RMS), a result much better than premission goals. While the orbit accuracy goal for T/P has been far surpassed geoid errors still prevent the absolute determination of the ocean dynamic topography for wavelengths shorter than about 2500 km. Only a dedicated gravitational field satellite mission will likely provide the necessary improvement in the geoid.

Commissioning of an APPLE-II Undulator at Daresbury Laboratory for the SRS

CERN Document Server

Clarke, James; Scott, Duncan; Shepherd, Ben; Wyles, Naomi

2005-01-01

A new variable polarisation undulator of the APPLE-II type has been designed and constructed at Daresbury Laboratory. Initial magnet testing of the 56mm period device was followed by an intensive period of shimming to improve the field quality. After this was successfully completed the undulator was installed into the SRS and tests made of the effect of the device upon the electron beam. This beam commissioning was completed in a very short space of time with the beamline being given full control of the gap and phase of the magnet within a few weeks of installation. This paper summarises the measurement of the magnet and the shimming techniques employed to improve the field quality. It also describes the effect of the device upon the stored 2 GeV electron beam and the measures taken to minimise these effects during user operations.

Thermal analysis of the first canted-undulator front-end components at SSRF

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhongmin, E-mail: xuzhongmin@sinap.ac.cn; Feng, Xinkang; Wang, Naxiu; Wu, Guanyuan; Zhang, Min; Wang, Jie

2015-02-21

The performance of three kinds of masks: pre-mask, splitter mask and fixed mask-photon shutter, used for the first canted-undulator front end under heat loads at SSRF, is studied. Because these components are shared with two beamlines, the X-rays from both dual undulators and bending magnets can strike on them. Under these complicated conditions, they will absorb much more thermal power than when they operate in usual beamline. So thermal and stress analysis is indispensable for their mechanical design. The method of applying the non-uniform power density using Ansys is presented. During thermal stress analysis, the normal operation or the worst possible case is considered. The finite element analyses results, such as the maximum temperature of the body and the cooling wall and the maximum stress of these components, show the design of them is reasonable and safe.

Development and operation of a Pr_{2}Fe_{14}B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

Directory of Open Access Journals (Sweden)

C. Benabderrahmane

2017-03-01

Full Text Available 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_{2}Fe_{14}B (Rare Earth based magnets at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr_{2}Fe_{14}B instead of Nd_{2}Fe_{14}B, 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 Pr_{2}Fe_{14}B 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.

Undulating fins produce off-axis thrust and flow structures.

Science.gov (United States)

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.

Spontaneous and stimulated undulator radiation by an ultra-relativistic positron channeling in a periodically bent crystal

International Nuclear Information System (INIS)

Krause, W.; Korol, A.V.; Solov'yov, A.V.; Greiner, W.

2001-01-01

We discuss the radiation generated by positrons channeling in a crystalline undulator. The undulator is produced by periodically bending a single crystal with an amplitude much larger than the interplanar spacing. Different approaches for bending the crystal are described and the restrictions on the parameters of the bending are discussed. We also present numeric calculations of the spontaneous emitted radiation and estimate the conditions for stimulated emission. Our investigations show that the proposed mechanism could be an interesting source for high energy photons and is worth to be studied experimentally

The Analysis of Height System Definition and the High Precision GNSS Replacing Leveling Method

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ZHANG Chuanyin

2017-08-01

Full Text Available Based on the definition of height system, the gravitational equipotential property of height datum surface is discussed in this paper, differences of the heights at ground points that defined in different height systems are tested and analyzed as well. A new method for replacing leveling using GNSS is proposed to ensure the consistency between GNSS replacing leveling and spirit leveling at mm accuracy level. The main conclusions include:①For determining normal height at centimeter accuracy level, the datum surface of normal height should be the geoid. The 1985 national height datum of China adopts normal height system, its datum surface is the geoid passing the Qingdao zero point.②The surface of equi-orthometric height in the near earth space is parallel to the geoid. The combination of GNSS precise positioning and geoid model can be directly used for orthometric height determination. However, the normal height system is more advantageous for describing the terrain and relief.③Based on the proposed method of GNSS replacing leveling, the errors in geodetic height affect more on normal height result than the errors of geoid model, the former is about 1.5 times of the latter.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

The U5.0 Undulator for the Advanced Light Source

International Nuclear Information System (INIS)

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1992-01-01

The U5.0 Undulator, an 89 period, 5 cm period length, 4.6 m long insertion device has been designed, is being fabricated, and is scheduled for completion in early 1992. This undulator will be the first high brightness source, in the 50 to 1,500 eV range, for the Advanced Light Source at the Lawrence Berkeley Laboratory. A hybrid magnetic configuration using Nd--Fe--B permanent magnet material and vanadium permendur poles has been selected to achieve the field quality needed to meet performance requirements. The magnetic structure is modular with each half consisting of five assembly sections, which provide the periodic structure, and end structures, for entrance and exit correction, mounted on a steel backing beam. Each assembly section consists of 35 half-period pole assemblies bolted to a mount. The required 0.837 T effective peak field at a 1.4 cm gap has been verified with model measurements. Vertical field integral correction is accomplished with the end structures, each having an arrangement of permanent magnet rotors which will be adjusted to minimize electron beam missteering over the undulator operating field range. To reduce the effect of environmental fields, the steel backing beams are connected through parallel, low-reluctance, Ni--Fe hinges. The magnetic structure is connected through four rollernuts to the drive system that provides gap adjustment with an arrangement of roller screws, chain drives, a gear reduction unit, and a stepper motor driven by a closed loop control system. Magnetic structure and drive system support are from a 2.4 m high structure which includes a support base with four vertical supports. The vacuum chamber design is a two-piece machined and welded 5083-H321 aluminum construction of 5.1 m length. Pumping is with a combination of ion, titanium sublimation pump and nonevaporable getter pumps. Magnetic design, subsystem design, and fabrication progress are presented

Design, Implementation and Control of a Fish Robot with Undulating Fins

Directory of Open Access Journals (Sweden)

Mohsen Siahmansouri

2011-11-01

Full Text Available Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the overall fin trajectory has also been discussed. This propulsive force can be adjusted and directed for fish robot manoeuvre by a mechanical system with two servomotors. These servomotors regulate the direction and depth of swimming. A wireless remote control system is designed to adjust the servomotors which enables us to control revolution, speed and phase differences of neighbor servomotors of fins. Finally, Field trials are conducted in an outdoor pool to demonstrate the relationship between robotic fish speed and fin parameters like phase difference, the number of phase and undulatory amplitude.

Investigating excitation-dependent and fringe-field effects of electromagnet and permanent-magnet phase shifters for a crossed undulator

Energy Technology Data Exchange (ETDEWEB)

Chung, Ting-Yi, E-mail: chung.albert@nsrrc.org.tw [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Yang, Chih-Sheng; Chu, Yun-Liang; Lin, Fu-Yuan; Jan, Jyh-Chyuan [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Hwang, Ching-Shiang [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Department of Electrophysics, National Chiao Tung University, Hsinchu 30050, Taiwan (China)

2017-04-01

To enhance the flux density or to control polarization, a phase shifter was designed and used to modulate the phase matching between segmented undulators. A larger hysteresis loop causes, however, a repeatability issue in the phase matching; the fringe field of the phase shifter creates an extra magnetic-field error. The design of the phase shifter must therefore minimize the hysteresis loop and fringe field to maintain the phases exact and to ignore the crosstalk effect. Two critical issues are the hysteresis-loop problem and the fringe-field effect, which determine the radiation performance and the stability of the ring. To investigate these issues, a phase shifter was constructed to operate in accordance with electromagnetic- and permanent-type magnets; the results from the field measurements and shims are discussed here. The shimming algorithm and a compact permanent-magnet phase shifter that eliminates the issues are also presented.

An acoustical research of the undulating wooden ceiling in the Vyborg Library

DEFF Research Database (Denmark)

Mortensen, Bo

2004-01-01

Much has been written about the Undulating Ceiling at the lecture hall of the Vyborg Library. Alvar Aalto himself claimed the ceiling to be "ninety-nine per cent acoustically perfect" and the sketches showing the acoustical considerations behind the ceiling-design is often reproduced. But how did...

Well known outstanding geoid and relief depressions as regular wave woven features on Eartg (Indian geoid minimum), Moon (SPA basin), Phobos (Stickney crater), and Miranda (an ovoid).

Science.gov (United States)

Kochemasov, Gennady G.

2010-05-01

A very unreliable interpretation of the deepest and large depressions on the Moon and Phobos as the impact features is not synonymous and causes many questions. A real scientific understanding of their origin should take into consideration a fact of their similar tectonic position with that of a comparable depression on so different by size, composition, and density heavenly body as Earth. On Earth as on other celestial bodies there is a fundamental division on two segments - hemispheres produced by an interference of standing warping wave 1 (long 2πR) of four directions [1]. One hemisphere is uplifted (continental, highlands) and the opposite subsided (oceanic, lowlands). Tectonic features made by wave 2 (sectors) adorn this fundamental structure. Thus, on the continental risen segment appear regularly disposed sectors, also uplifted and subsided. On the Earth's eastern continental hemisphere they are grouped around the Pamirs-Hindukush vertex of the structural octahedron made by interfering waves2. Two risen sectors (highly uplifted African and the opposite uplifted Asian) are separated by two fallen sectors (subsided Eurasian and the opposite deeply subsided Indoceanic). The Indoceanic sector with superposed on it subsided Indian tectonic granule (πR/4-structure) produce the deepest geoid minimum of Earth (-112 m). The Moon demonstrates its own geoid minimum of the same relative size and in the similar sectoral tectonic position - the SPA basin [2, 3]. This basin represents a deeply subsided sector of the sectoral structure around the Mare Orientale (one of vertices of the lunar structural octahedron). To this Mare converge four sectors: two subsided - SPA basin and the opposite Procellarum Ocean, and two uplifted - we call them the "Africanda sector" and the opposite "Antiafricanda one" to stress structural similarity with Earth [2]. The highest "Africanda sector" is built with light anorthosites; enrichment with Na makes them even less dense that is required

Unraveling African plate structure from elevation, geoid and geology data

Science.gov (United States)

Chardon, Dominique; Bajolet, Flora; Robert, Alexandra; Rouby, Delphine

2014-05-01

The aim of our project is to simulate the long-wavelength, flexural isostatic response of the African plate to sediment transfers due to Meso-Cenozoic erosion - deposition processes in order to extract the residual topography driven by mantle dynamics. Our work will be based on the reconstruction and subtraction of two continental-scale erosional-depositional surfaces of Eocene and Late Cretaceous ages and their offshore extensions. The first step of our project consists in computing crustal and lithospheric maps of the African plate considering its various crustal geological components (cratons, mobile belts, basins, rifts and passive margins of various ages and strengths). In order to consider these heterogeneities, we compute a 2D distribution of crustal densities and thermal parameters from geological data and use it as an input of our modeling. We combine elevation and geoid anomaly data using a thermal analysis, following the method of Fullea et al. (2007) in order to map crustal and lithospheric thicknesses. In this approach, we assume local isostasy and consider a four-layer model made of crust and lithospheric mantle plus seawater and asthenosphere. In addition, we compare our results with crustal thickness datasets compiled from bibliography, existing global models such as CRUST 1.0, and tomographic lithospheric models. The obtained crustal thicknesses range from 30 to 45km, with the thickest crust confined to the northern part of the West African Craton, the Kaapvaal craton, and the Congo cuvette. The crust in the East African Rift appears unrealistically thick (40-45 km) as it is not isotatically compensated, highlighting the dynamic effect of the African superswell. The thinnest crust (30-35km) follows a central East-West trend coinciding with Cretaceous rifts and the Cameroon volcanic line. Pan-African mobile belts yield intermediate values of ca. 35-40 km. The lithosphere reaches 250 km beneath cratons, but remains globally thin (ca. 150-180 km

Pulse propagation in free-electron lasers with a tapered undulator

International Nuclear Information System (INIS)

Goldstein, J.C.; Colson, W.B.

1981-01-01

The one-dimensional theory of short pulse propagation in free electron lasers is extended to tapered undulator devices and is used to study the behavior of an oscillator with parameter values close to those expected in forthcoming experiments. It is found that stable laser output is possible only over a small range of optical cavity lengths. Optical pulse characteristics are presented and are found to change considerably over this range

Fabrication and Test of a Nb$_{3}$Sn Model Magnet With Ceramic Insulation for the Next Generation Undulator of the LHC

CERN Document Server

Elias, N; Dalexandro, N; Giloux, C; Bordini, B; Maccaferri, R

2010-01-01

The future run of the Large Hadron Collider with lead ions will require important modifications in the synchrotron radiation profile monitor system, which at present comprises two superconducting undulators wound from Nb-Ti conductor, delivering 5 T in a 60 mm gap, and with a period of 280 mm. Whilst the gap and the nominal field of the future undulators will remain the same, the period shall be 140 mm, which translates to a peak field of over 8 T in the coils and hence requires the use of Nb$_{3}$Sn technology. In this paper the electromagnetic design of the undulator is summarized. We describe the fabrication of a race-track coil wound with a 0.8 mm diameter Nb$_{3}$Sn strand with ceramic insulation. Finally, the results of successful tests made at 4.3 K and 1.9 K in a mirror configuration are presented. 10 T at 4.3 K and 11.5 T at 1.9 K were measured in the yoke gap, thus validating this concept for the future undulator.

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

Science.gov (United States)

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2018-04-24

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.

Computation of the brightness of the variably-polarizing undulator

International Nuclear Information System (INIS)

Dattoli, G.; Torre, A.; Schettini, G.; Carpanese, M.

1999-02-01

Undulators, producing variably polarized radiation, generate magnetic fields which induce different types of electron motion (vertically, horizontally sinusoidal and helical). The properties of the emitted radiation reflect the complexity of the motion and cannot be described with the method based on the conventional Bessel functions expansion. It's shown that the problem can be overcome by exploiting a method which employs generalized forms of Bessel functions. The proposed technique provides an effective tool to analyze the properties of the emitted radiation [it

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

Science.gov (United States)

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.

Petrologically-constrained thermo-chemical modelling of cratonic upper mantle consistent with elevation, geoid, surface heat flow, seismic surface waves and MT data

Science.gov (United States)

Jones, A. G.; Afonso, J. C.

2015-12-01

The Earth comprises a single physio-chemical system that we interrogate from its surface and/or from space making observations related to various physical and chemical parameters. A change in one of those parameters affects many of the others; for example a change in velocity is almost always indicative of a concomitant change in density, which results in changes to elevation, gravity and geoid observations. Similarly, a change in oxide chemistry affects almost all physical parameters to a greater or lesser extent. We have now developed sophisticated tools to model/invert data in our individual disciplines to such an extent that we are obtaining high resolution, robust models from our datasets. However, in the vast majority of cases the different datasets are modelled/inverted independently of each other, and often even without considering other data in a qualitative sense. The LitMod framework of Afonso and colleagues presents integrated inversion of geoscientific data to yield thermo-chemical models that are petrologically consistent and constrained. Input data can comprise any combination of elevation, geoid, surface heat flow, seismic surface wave (Rayleigh and Love) data and receiver function data, and MT data. The basis of LitMod is characterization of the upper mantle in terms of five oxides in the CFMAS system and a thermal structure that is conductive to the LAB and convective along the adiabat below the LAB to the 410 km discontinuity. Candidate solutions are chosen from prior distributions of the oxides. For the crust, candidate solutions are chosen from distributions of crustal layering, velocity and density parameters. Those candidate solutions that fit the data within prescribed error limits are kept, and are used to establish broad posterior distributions from which new candidate solutions are chosen. Examples will be shown of application of this approach fitting data from the Kaapvaal Craton in South Africa and the Rae Craton in northern Canada. I

Magnetic field calculation of variably polarizing undulator (APPLE-type) for SX beamline in the SPring-8

International Nuclear Information System (INIS)

Kobayashi, Hideki; Sasaki, Shigemi; Shimada, Taihei; Takao, Masaru; Yokoya, Akinori; Miyahara, Yoshikazu

1996-03-01

This paper describes the design of a variably polarizing undulator (APPLE-type) to be installed in soft X-ray beamline in the SPring-8 facility. The magnetic field distribution and radiation spectrum expected from this undulator were calculated. The magnetic field strength is varied by changing the gap distance of upper and lower jaws, so it changes the photon energy in soft X-ray range. By moving the relative position of pairs of magnet rows (phase shift), the polarization of radiation is varied circularly, elliptically and linearly in the horizontal and vertical direction. We expect that right and left handed circular polarizations are obtained alternately at a rate of 1 Hz by high speed phase shifting. The repulsive and attractive magnetic force working on the magnet rows were calculated which interfere in phase shifting at high speed. The magnetic force changes with gap distance and phase shift position, and the magnetic force working on a row in the direction of phase shift becomes up to 500 kgf. The construction of this undulator is started in 1996, that will be inserted in the storage ring in 1997. (author)

Circular polarization opportunities at the SASE3 undulator line of the European XFEL

Energy Technology Data Exchange (ETDEWEB)

Serkez, Svitozar; Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2016-08-15

XFELs provide X-ray pulses with unprecedented peak brightness and ultrashort duration. They are usually driven by planar undulators, meaning that the output radiation is linearly polarized. For many experimental applications, however, polarization control is critical: besides the ability to produce linearly polarized radiation, one often needs the possibility of generating circularly polarized radiation with a high, stable degree of polarization. This may be achieved by using a first part of the XFEL undulator to produce bunching and then, by propagating the the bunched beam through an ''afterburner'' - a short undulator with tunable polarization, where only limited gain takes place. One of the issues that one needs to consider in this case is the separation of the circularly polarized radiation obtained in the radiator from the linearly polarized background produced in the first part of the FEL. In this article we review several methods to do so, including the inverse tapering technique. In particular, we use the Genesis FEL code to simulate a case study pertaining to the SASE3 FEL line at the European XFEL with up-to-date parameters and we confirm that a high degree of circular polarization is expected. Moreover, we propose to further improve the effectiveness of the inverse tapering technique either via angular separation of the linearly polarized radiation or strongly defocusing it at the sample position. In this way we exploit the unique flexibility of the European XFEL from both the electron beam and the photon beam optics side.

Use of recent geoid models to estimate mean dynamic topography and geostrophic currents in South Atlantic and Brazil Malvinas confluence

Directory of Open Access Journals (Sweden)

Alexandre Bernardino Lopes

2012-03-01

Full Text Available The use of geoid models to estimate the Mean Dynamic Topography was stimulated with the launching of the GRACE satellite system, since its models present unprecedented precision and space-time resolution. In the present study, besides the DNSC08 mean sea level model, the following geoid models were used with the objective of computing the MDTs: EGM96, EIGEN-5C and EGM2008. In the method adopted, geostrophic currents for the South Atlantic were computed based on the MDTs. In this study it was found that the degree and order of the geoid models affect the determination of TDM and currents directly. The presence of noise in the MDT requires the use of efficient filtering techniques, such as the filter based on Singular Spectrum Analysis, which presents significant advantages in relation to conventional filters. Geostrophic currents resulting from geoid models were compared with the HYCOM hydrodynamic numerical model. In conclusion, results show that MDTs and respective geostrophic currents calculated with EIGEN-5C and EGM2008 models are similar to the results of the numerical model, especially regarding the main large scale features such as boundary currents and the retroflection at the Brazil-Malvinas Confluence.A utilização de modelos geoidais na determinação da Topografia Dinâmica Média foi impulsionada com o lançamento dos satélites do sistema GRACE, já que seus modelos apresentam precisão e resolução espacial e temporal sem precedentes. No presente trabalho, além do modelo de nível médio do mar DNSC08, foram utilizados os seguintes modelos geoidais com o objetivo de calcular as TDMs: EGM96, EIGEN-5C e EGM2008. No método adotado, foram calculadas as respectivas correntes geostróficas para o Atlântico Sul a partir das TDMs. O grau e ordem dos modelos geoidais influenciam diretamente na determinação da TDM e correntes. Neste trabalho verificou-se que presença de ruídos da TDM requer a utilização de técnicas de filtragem

Exploring the undulating plateau: the future of global oil supply.

Science.gov (United States)

Jackson, Peter M; Smith, Leta K

2014-01-13

In this paper, we analyse the factors that will influence long-term oil supply and describe the future form of the global oil supply profile as an 'undulating plateau' rather than an irreversible, short-term peak or an ever upward trend of increasing production. The ultimate transition from a world of relatively plentiful and cheap oil to one of tight supply and high cost will be slow and challenging. An understanding of the signposts for the future path of supply and the drivers of that profile will be critical to managing the transition. The ultimate form of the global supply curve may well be dictated by demand evolution rather than a limited resource endowment in the longer term. Several factors will probably control future global oil supply. We believe that the scale of global oil resource will not constitute a physical supply limit for at least the next two or three decades. However, all categories of oil resources are already more expensive to develop than in the past, requiring high oil prices to stimulate supply growth. Lower rates of oil demand growth relative to economic growth, combined with more challenging supply growth, will probably lead to an undulating plateau sometime after 2040, with demand from non-Organization for Economic Cooperation and Development states continuing to dominate. Upstream investment requirements and oil price volatility will increase towards and beyond the undulating production plateau. In this new world, high oil prices will induce demand destruction, fuel substitution and ever increasing energy efficiency. As we discuss below, the fundamental differences between the IHS Cambridge Energy Research Associates' (IHS CERA) view of the future of oil supply and many peak oil supply models are the timing of the onset of a dramatic slowdown in the rate of growth of supply and the existence or otherwise of a production plateau. We do not dispute that supply will plateau and eventually fall; the question is when, how and at what price

Multiple station beamline at an undulator x-ray source

DEFF Research Database (Denmark)

Als-Nielsen, J.; Freund, A.K.; Grübel, G.

1994-01-01

The undulator X-ray source is an ideal source for many applications: the beam is brilliant, highly collimated in all directions, quasi-monochromatic, pulsed and linearly polarized. Such a precious source can feed several independently operated instruments by utilizing a downstream series of X......-ray transparent monochromator crystals. Diamond in particular is an attractive monochromator as it is rather X-ray transparent and can be fabricated to a high degree of crystal perfection. Moreover, it has a very high heat conductivity and a rather small thermal expansion so the beam X-ray heat load problem...

Aspects of Remote Sensing in the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) Project

DEFF Research Database (Denmark)

Hilger, Klaus Baggesen; Nielsen, Allan Aasbjerg; Knudsen, Per

1999-01-01

The general objectives of the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) project are presented. These include analyses of the dynamics of the ocean and its characteristics. The analyses are mainly based on remote sensing. As an example a data set obtained by the multi-channel Sea-viewing...... Wide Field-of-view Sensor (SeaWiFs) is analysed. The presentation results include the computed principal components (PC) and the maximum autocorrelation factors (MAF). Both methods are expected to be incorporated into future analyses of the state of the ocean....

Initial studies of Bremsstrahlung energy deposition in small-bore superconducting undulator structures in linac environments

Energy Technology Data Exchange (ETDEWEB)

Cremer, T.; Tatchyn, R. [Stanford Univ., CA (United States)

1995-12-31

One of the more promising technologies for developing minimal-length insertion devices for linac-driven, single-pass Free Electron Lasers (FELs) operating in the x-ray range is based on the use of superconducting (SC) materials. In recent FEL simulations, for example, a bifilar helical SC device with a 2 cm period and 1.8 T field was found to require a 30 m saturation length for operation at 1.5{Angstrom} on a 15 GeV linac, more than 40% shorter than an alternative hybrid/permanent magnet (hybrid/PM) undulator. AT the same time, however, SC technology is known to present characteristic difficulties for insertion device design, both in engineering detail and in operation. Perhaps the most critical problem, as observed, e.g., by Madey and co-workers in their initial FEL experiments, was the frequent quenching induced by scattered electrons upstream of their (bifilar) device. Postulating that this quenching was precipitated by directly-scattered or bremsstrahlung-induced particle energy deposited into the SC material or into material contiguous with it, the importance of numerical and experimental characterizations of this phenomenon for linac-based, user-facility SC undulator design becomes evident. In this paper we discuss selected prior experimental results and report on initial EGS4 code studies of scattered and bremsstrahlung induced particle energy deposition into SC structures with geometries comparable to a small-bore bifilar helical undulator.

Tuning and switching of band gap of the periodically undulated beam by the snap through buckling

Directory of Open Access Journals (Sweden)

Y. Li

2017-05-01

Full Text Available We propose highly tuning and switching band gaps of phononic crystals through the snap through buckling by investigating wave propagation in a designed tractable undulated beam with single material and periodically arched shape. A series of numerical analyses are conducted to offer a thorough understanding of the evolution of the band gaps as a function of the vertical applied load. We find out that the interesting snap through buckling induced by the vertical load can alter the width of the band gap of the undulated beam dramatically, even switch them on and off. Our researches show an effective strategy to tune the band gaps of phononic crystals through the snap through buckling behavior.

Low-frequency quadrupole impedance of undulators and wigglers

Directory of Open Access Journals (Sweden)

A. Blednykh

2016-10-01

Full Text Available 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}. 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 fully saturated (μ_{r}=1.

Linac Coherent Light Source Undulator RF BPM System

International Nuclear Information System (INIS)

Lill, R.M.; Morrison, L.H.; Waldschmidt, G.J.; Walters, D.R.; Argonne; Johnson, R.; Li, Z.; Smith, S.; Straumann, T.; SLAC

2007-01-01

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, and prototype test results

Design Features of a Planar Hybrid/Permanent Magnet Strong Focusing Undulator for Free Electron Laser (FEL) And Synchrotron Radiation (SR) Applications

Energy Technology Data Exchange (ETDEWEB)

Tatchyn, Roman; /SLAC

2011-09-09

Insertion devices for Angstrom-wavelength Free Electron Laser (FEL) amplifiers driven by multi-GeV electron beams generally require distributed focusing substantially stronger than their own natural focusing fields. Over the last several years a wide variety of focusing schemes and configurations have been proposed for undulators of this class, ranging from conventional current-driven quadrupoles external to the undulator magnets to permanent magnet (PM) lattices inserted into the insertion device gap. In this paper we present design studies of a flexible high-field hybrid/PM undulator with strong superimposed planar PM focusing proposed for a 1.5 Angstrom Linac Coherent Light Source (LCLS) driven by an electron beam with a 1 mm-mr normalized emittance. Attainable field parameters, tuning modes, and potential applications of the proposed structure are discussed.

A fixed angle double mirror filter for preparing a pink undulator beam at the Advanced Photon Source

International Nuclear Information System (INIS)

Dufresne, E.; Sanchez, T.; Nurushev, T.; Clarke, R.; Dierker, S.B.

2000-01-01

Recent advances in X-ray Photon Correlation Spectroscopy (XPCS) use the full bandwidth of an undulator harmonic in order to maximize the coherent flux for small angle X-ray scattering experiments. X-ray mirrors and filters are typically used to select a given harmonic of the spectrum. At the University of Michigan/Howard University/Lucent Technologies, Bell Labs, Collaborative Access Team (MHATT-CAT) undulator beamline of the Advanced Photon Source, we have designed a fixed-angle Double Mirror Filter which will provide a 'pink beam' (i.e., 2-3% bandwidth) for XPCS experiments. This device uses two small mirrors which vertically reflect a 0.1 mmx0.1 mm white beam in a symmetric geometry. The doubly reflected beam propagates parallel to the incident white beam, but is offset vertically by 35 mm. Using the standard offset of the APS allows one to stop the white beam with a standard APS beam stop. In this report, we will describe our design considerations for this instrument. We also report the results of preliminary tests of the performance. The mirrors preserve the transverse coherence of the source, and filter the undulator spectrum as expected

An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

Energy Technology Data Exchange (ETDEWEB)

Anania, M. P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); INFN, Laboratori Nazionali di Frascati, I-00044 Frascati (Italy); Brunetti, E.; Wiggins, S. M.; Grant, D. W.; Welsh, G. H.; Issac, R. C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; Jaroszynski, D. A., E-mail: d.a.jaroszynski@strath.ac.uk [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Geer, S. B. van der; Loos, M. J. de [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands); Poole, M. W.; Shepherd, B. J. A.; Clarke, J. A. [ASTeC, STFC, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Gillespie, W. A. [SUPA, School of Engineering, Physics and Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); MacLeod, A. M. [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee DD1 1HG (United Kingdom)

2014-06-30

Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 10{sup 6} per shot for a 100 period undulator, with a mean peak brilliance of 1 × 10{sup 18} photons/s/mrad{sup 2}/mm{sup 2}/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs.

Free-Air Gravity Map of Taiwan and Its Applications

Directory of Open Access Journals (Sweden)

Horng-Yuan Yen

1990-01-01

Full Text Available An island-wide gravity in Taiwan was conducted by the Institute of Earth Sciences, Academia Sinica, between 1980 and 1987. The 603 stations at which the gravity values were determined included 308 points in the 500 m or higher mountain range where few readings were available previously. The average spacing of the stations in the present survey is about 7 km apart. A new Free-air gravity anomaly map has been constructed based on these values. The map is dominated by a NNE-SSW gravity high trend with a maximum value of 300 mgal, that follows closely the Central Range, a folded and faulted mountain belt with many peaks 3000 m or higher. The magnitude of the Free-air anomaly in the Taiwan area is quite large compared to that elsewhere in the world. The good correlation between the Free-air anomaly and elevation suggests that the Taiwan area is not in isostatic equilibrium. An average surface rock density of 2.57 g cm-3 is estimated from the Free-air gravity data by using the least-squares method. This value can be used for both terrain and Bouguer corrections. The undulation of the geoid and the deflections of the vertical in the Taiwan area are also calculated by using the Free-air anomaly data. The geoid undulation is not rugged over the Taiwan area. The maximum difference is about 5 m. And the deflection of the vertical seems mainly to be affected by both land and submarine topographies.

Results of stretched wire field integral measurements on the mini-undulator magnet - comparison of results obtained from circular and translational motion of the integrating wire

International Nuclear Information System (INIS)

Solomon, L.

1998-05-01

Measurements of the multipole content of the Mini-Undulator magnet have been made with two different integrating wire techniques. Both measurements used 43 strand Litz wire stretched along the length of the magnet within the magnet gap. In the first technique, the wire motion was purely translational, while in the second technique the wire was moved along a circular path. The induced voltage in the Litz wire was input into a Walker integrator, and the integrator output was analyzed as a function of wire position for determination of the multipole content of the magnetic field. The mini-undulator magnet is a 10 period, 80 mm per period hybrid insertion device. For all the data contained herein the magnet gap was set at 49 mm. In the mini-undulator magnet, the iron poles are 18mm x 32mm x 86 mm, and the Samarium Cobalt permanent magnet blocks are 22mm x 21mm x 110mm. For this magnet, which is a shortened prototype for the NSLS Soft X-Ray Undulator Magnet, the undulator parameter K = 0.934 B (Tesla)λ(cm), and B(tesla) = 0.534/sinh(πGap/λ). At a gap of 49 mm, the magnetic field is 1590 Gauss

A new Ellipsoidal Gravimetric-Satellite Altimetry Boundary Value Problem; Case study: High Resolution Geoid of Iran

Science.gov (United States)

Ardalan, A.; Safari, A.; Grafarend, E.

2003-04-01

A new ellipsoidal gravimetric-satellite altimetry boundary value problem has been developed and successfully tested. This boundary value problem has been constructed for gravity observables of the type (i) gravity potential (ii) gravity intensity (iii) deflection of vertical and (iv) satellite altimetry data. The developed boundary value problem is enjoying the ellipsoidal nature and as such can take advantage of high precision GPS observations in the set-up of the problem. The highlights of the solution are as follows: begin{itemize} Application of ellipsoidal harmonic expansion up to degree/order and ellipsoidal centrifugal field for the reduction of global gravity and isostasy effects from the gravity observable at the surface of the Earth. Application of ellipsoidal Newton integral on the equal area map projection surface for the reduction of residual mass effects within a radius of 55 km around the computational point. Ellipsoidal harmonic downward continuation of the residual observables from the surface of the earth down to the surface of reference ellipsoid using the ellipsoidal height of the observation points derived from GPS. Restore of the removed effects at the application points on the surface of reference ellipsoid. Conversion of the satellite altimetry derived heights of the water bodies into potential. Combination of the downward continued gravity information with the potential equivalent of the satellite altimetry derived heights of the water bodies. Application of ellipsoidal Bruns formula for converting the potential values on the surface of the reference ellipsoid into the geoidal heights (i.e. ellipsoidal heights of the geoid) with respect to the reference ellipsoid. Computation of the high-resolution geoid of Iran has successfully tested this new methodology!

Preparing the BESSY APPLE Undulators for Top-Up Operation

Science.gov (United States)

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.

A second-generation superconducting undulator cryostat for the APS

Science.gov (United States)

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.

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

Science.gov (United States)

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.

High-field strong-focusing undulator designs for X-ray Linac Coherent Light Source (LCLS) applications

International Nuclear Information System (INIS)

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

1995-01-01

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 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 for a 4.5--1.5 angstrom LCLS based on superconducting (SC), hybrid/PM, and pulsed-Cu technologies

Wakefields in the LCLS Undulator Transitions

Energy Technology Data Exchange (ETDEWEB)

Bane, Karl L.F.; /SLAC; Zagorodnov, Igor A.; /DESY

2005-08-15

We have studied longitudinal wakefields of very short bunches in non-cylindrically symmetric (3D) vacuum chamber transitions using analytical models and the computer program ECHO. The wake (for pairs of well-separated, non-smooth transitions) invariably is resistive, with its shape proportional to the bunch distribution. For the example of an elliptical collimator in a round beam pipe we have demonstrated that--as in the cylindrically symmetric (2D) case--the wake can be obtained from the static primary field of the beam alone. We have obtained the wakes of the LCLS rectangular-to-round transitions using indirect (numerical) field integration combined with a primary beam field calculation. For the LCLS 1 nC bunch charge configuration we find that the total variation in wake-induced energy change is small (0.03% in the core of the beam, 0.15% in the horns of the distribution) compared to that due to the resistive wall wakes of the undulator beam pipe (0.6%).

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

Science.gov (United States)

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.

Nonlinear undulator tapering in conventional SASE regime at baseline electron beam parameters as a way to optimize the radiation characteristics of the European XFEL

Energy Technology Data Exchange (ETDEWEB)

Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany)

2013-09-15

We demonstrate that the output radiation characteristics of the European XFEL sources at nominal operation point can be easily made significantly better than what is currently reported in the TDRs of scientific instruments and X-ray optics. In fact, the output SASE characteristics of the baseline European XFEL have been previously optimized assuming uniform undulators at a nominal operating point of 5 kA peak current, without considering the potential of undulator tapering in the SASE regime. In order to illustrate this point, we analyze the case of an electron bunch with nominal parameters. Based on start-to-end simulations, we demonstrate that nonlinear undulator tapering allows one to achieve up to a tenfold increase in peak power and photon spectral density in the conventional SASE regime, without modification to the baseline design. The FEL code Genesis has been extensively used for these studies. In order to increase our confidence in simulation results, we cross-checked outcomes by reproducing simulations in the deep nonlinear SASE regime with tapered undulator using the code ALICE.

Lateral variation in upper mantle temperature and composition beneath mid-ocean ridges inferred from shear-wave propagation, geoid, and bathymetry. Ph.D. Thesis

Science.gov (United States)

Sheehan, Anne Francis

1991-01-01

Resolution of both the extent and mechanism of lateral heterogeneity in the upper mantle constraints the nature and scales of mantle convection. Oceanic regions are of particular interest as they are likely to provide the closest glimpse at the patterns of temperature anomalies and convective flow in the upper mantle because of their young age and simple crustal structure relative to continental regions. Lateral variations were determined in the seismic velocity and attenuation structure of the lithosphere and astenosphere beneath the oceans, and these seismological observations were combined with the data and theory of geoid and bathymetry anomalies in order to test and improve current models for seafloor spreading and mantle convection. Variations were determined in mantle properties on a scale of about 1000 km, comparable to the thickness of the upper mantle. Seismic velocity, geoid, and bathymetry anomalies are all sensitive to variations in upper mantle density, and inversions were formulated to combine quantitatively these different data and to search for a common origin. Variations in mantle density can be either of thermal or compositional origin and are related to mantle convection or differentiation.

Linac coherent light source (LCLS) undulator RF BPM system

International Nuclear Information System (INIS)

Lill, R.; Waldschmidt, G.; Morrison, L.; Smith, S.; Straumann, T; Li, Z.; Johnson, R.

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, and prototype test results.

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

Directory of Open Access Journals (Sweden)

S. Casalbuoni

2016-11-01

Full Text Available 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.

Undulator-Based Production of Polarized Positrons, A Proposal for the 50-GeV Beam in the FFTB

Energy Technology Data Exchange (ETDEWEB)

Alexander, G

2004-03-25

The full exploitation of the physics potential of future linear colliders such as the JLC, NLC, and TESLA will require the development of polarized positron beams. In the proposed scheme of Balakin and Mikhailichenko [1] a helical undulator is employed to generate photons of several MeV with circular polarization which are then converted in a relatively thin target to generate longitudinally polarized positrons. This experiment, E-166, proposes to test this scheme to determine whether such a technique can produce polarized positron beams of sufficient quality for use in future linear colliders. The experiment will install a meter-long, short-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) at SLAC. A low-emittance 50-GeV electron beam passing through this undulator will generate circularly polarized photons with energies up to 10 MeV. These polarized photons are then converted to polarized positrons via pair production in thin targets. Titanium and tungsten targets, which are both candidates for use in linear colliders, will be tested. The experiment will measure the flux and polarization of the undulator photons, and the spectrum and polarization of the positrons produced in the conversion target, and compare the measurement results to simulations. Thus the proposed experiment directly tests for the first time the validity of the simulation programs used for the physics of polarized pair production in finite matter, in particular the effects of multiple scattering on polarization. Successful comparison of the experimental results to the simulations will lead to greater confidence in the proposed designs of polarized positrons sources for the next generation of linear colliders. This experiment requests six-weeks of time in the FFTB beam line: three weeks for installation and setup and three weeks of beam for data taking. A 50-GeV beam with about twice the SLC emittance at a repetition rate of 30 Hz is required.

Undulator-Based Production of Polarized Positrons, A Proposal for the 50-GeV Beam in the FFTB

Energy Technology Data Exchange (ETDEWEB)

G. Alexander; P. Anthony; V. Bharadwaj; Yu.K. Batygin; T. Behnke; S. Berridge; G.R. Bower; W. Bugg; R. Carr; E. Chudakov; J.E. Clendenin; F.J. Decker; Yu. Efremenko; T. Fieguth; K. Flottmann; M. Fukuda; V. Gharibyan; T. Handler; T. Hirose; R.H. Iverson; Yu. Kamyshkov; H. Kolanoski; T. Lohse; Chang-guo Lu; K.T. McDonald; N. Meyners; R. Michaels; A.A. Mikhailichenko; K. Monig; G. Moortgat-Pick; M. Olson; T. Omori; D. Onoprienko; N. Pavel; R. Pitthan; M. Purohit; L. Rinolfi; K.P. Schuler; J.C. Sheppard; S. Spanier; A. Stahl; Z.M. Szalata; J. Turner; D. Walz; A. Weidemann; J. Weisend

2003-06-01

The full exploitation of the physics potential of future linear colliders such as the JLC, NLC, and TESLA will require the development of polarized positron beams. In the proposed scheme of Balakin and Mikhailichenko [1] a helical undulator is employed to generate photons of several MeV with circular polarization which are then converted in a relatively thin target to generate longitudinally polarized positrons. This experiment, E-166, proposes to test this scheme to determine whether such a technique can produce polarized positron beams of sufficient quality for use in future linear colliders. The experiment will install a meter-long, short-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) at SLAC. A low-emittance 50-GeV electron beam passing through this undulator will generate circularly polarized photons with energies up to 10 MeV. These polarized photons are then converted to polarized positrons via pair production in thin targets. Titanium and tungsten targets, which are both candidates for use in linear colliders, will be tested. The experiment will measure the flux and polarization of the undulator photons, and the spectrum and polarization of the positrons produced in the conversion target, and compare the measurement results to simulations. Thus the proposed experiment directly tests for the first time the validity of the simulation programs used for the physics of polarized pair production in finite matter, in particular the effects of multiple scattering on polarization. Successful comparison of the experimental results to the simulations will lead to greater confidence in the proposed designs of polarized positrons sources for the next generation of linear colliders. This experiment requests six-weeks of time in the FFTB beam line: three weeks for installation and setup and three weeks of beam for data taking. A 50-GeV beam with about twice the SLC emittance at a repetition rate of 30 Hz is required.

Overview of the superconducting undulator development program at ANKA

Energy Technology Data Exchange (ETDEWEB)

Casalbuoni, S., E-mail: sara.casalbuoni@kit.edu; Cecilia, A.; Gerstl, S.; Glamann, N.; Grau, A.; Holubek, T.; Meuter, C.; Saez de Jauregui, D.; Voutta, R. [ANKA, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Boffo, C.; Gerhard, Th.; Turenne, M.; Walter, W. [Babcock Noell GmbH, Alfred Nobel Str. 20, 97080 Würzburg (Germany)

2016-07-27

Superconducting undulators (SCUs) have the potential to reach higher brilliance and flux with respect to the state of the art permanent magnet insertion devices. ANKA is collaborating with the industrial partner Babcock Noell GmbH (BNG) to realize NbTi conduction cooled planar devices for low emittance light sources, and is developing the instrumentation to characterize the magnetic field properties and to measure the beam heat load to a cold bore needed for the cryogenic design of SCUs. We present here: the most recent results obtained within the ANKA-BNG collaboration, the progress achieved in the development of the instrumentation, and the in house studies on the application of high temperature superconducting (HTS) tape to the SCU technology.

Generation of radiation by intense plasma and electromagnetic undulators

International Nuclear Information System (INIS)

Joshi, C.

1989-01-01

This is a second year progress report which details the work on the generation of radiation by intense plasma and electromagnetic undulators being carried out at UCLA. The status of the experimental work is described and the future directions are outlined. We have completed the first phase of experiments on the plasma wiggler generation and characterization. Suitability of a null-pinch as a plasma source was investigated in great detail. It is found that a w of a few percent can be excited but there are trapped magnetic fields within null-pinch plasma which hinder the injection of the electrons. A new more uniform and field-free plasma source is now being characterized

Generation of radiation by intense plasma and electromagnetic undulators

International Nuclear Information System (INIS)

Joshi, C.

1989-01-01

This is a second year progress report which details the work on the generation of radiation by intense plasma and electromagnetic undulators being carried out at UCLA. The status of the experimental work is described and the future directions are outlined. We have completed the first phase of experiments on the plasma wiggler generation and characterization. Suitability of a θ-pinch as a plasma source was investigated in great detail. It is found that a w of a few percent can be excited but there are trapped magnetic fields within θ-pinch plasma which hinder the injection of the electrons. A few more uniform and field-free plasma source is now being characterized. 8 refs., 5 figs

Use of a mirror as the first optical component for an undulator beamline at the APS

International Nuclear Information System (INIS)

Yun, W.; Khounsary, A.; Lai, B.; Gluskin, E.

1992-09-01

In the design of Sector II of the Synchrotron Radiation Instrumentation (SRI) CAT, an x-ray mirror with multiple coatings is chosen as the first optical component of the undulator beamline. Two significant advantages of using the mirror are: A significant reduction in the peak radiation heat flux and total power on the downstream monochromator, and (2) availability of the wide-bandpass undulator spectrum between 0--30 key to experimental stations with substantially reduced radiation shielding requirements. The second advantage also allows us to place the monochromator outside the first optics enclosure (FOE) at a large distance from the source to further reduce the peak heat flux on the monochromator. The combined effect is that the inclined crystal monochromator may not be necessary, and a multilayer monochromator can be used because the expected heat fluxes are less than the value that has been demonstrated for those monochromators

Undulative induction electron accelerator for the waste and natural water purification systems

CERN Document Server

Kulish, Victor V; Gubanov, I V

2001-01-01

The project analysis of Undulative Induction Accelerator (EH - accelerator) for the waste and natural water purification systems is accomplished. It is shown that the use of the four-channel design of induction block and the standard set of auxiliary equipment (developed earlier for the Linear Induction Accelerators - LINACs) allow to construct commercially promising purification systems. A quality analysis of the accelerator is done and the optimal parameters are chosen taking into account the specific sphere of its usage.

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

Science.gov (United States)

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.

Micropole undulators in synchrotron radiation technology: Design and construction of a submillimeter period prototype with a 3 kilogauss peak field at SSRL

International Nuclear Information System (INIS)

Tatchyn, R.; Csonka, P.

1987-01-01

The availability of undulators with submillimeter periods profoundly affects 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

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

Directory of Open Access Journals (Sweden)

Jere Harrison

2012-07-01

Full Text Available 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 15  μm. Simulations indicate that magnetic fields as large as 1.5 T across 50  μm 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 12.5  μm 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.

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

Science.gov (United States)

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.

A contrastive study on the influences of radial and three-dimensional satellite gravity gradiometry on the accuracy of the Earth's gravitational field recovery

International Nuclear Information System (INIS)

Zheng Wei; Hsu Hou-Tse; Zhong Min; Yun Mei-Juan

2012-01-01

The accuracy of the Earth's gravitational field measured from the gravity field and steady-state ocean circulation explorer (GOCE), up to 250 degrees, influenced by the radial gravity gradient V zz and three-dimensional gravity gradient V ij from the satellite gravity gradiometry (SGG) are contrastively demonstrated based on the analytical error model and numerical simulation, respectively. Firstly, the new analytical error model of the cumulative geoid height, influenced by the radial gravity gradient V zz and three-dimensional gravity gradient V ij are established, respectively. In 250 degrees, the GOCE cumulative geoid height error measured by the radial gravity gradient V zz is about 2 ½ times higher than that measured by the three-dimensional gravity gradient V ij . Secondly, the Earth's gravitational field from GOCE completely up to 250 degrees is recovered using the radial gravity gradient V zz and three-dimensional gravity gradient V ij by numerical simulation, respectively. The study results show that when the measurement error of the gravity gradient is 3 × 10 −12 /s 2 , the cumulative geoid height errors using the radial gravity gradient V zz and three-dimensional gravity gradient V ij are 12.319 cm and 9.295 cm at 250 degrees, respectively. The accuracy of the cumulative geoid height using the three-dimensional gravity gradient V ij is improved by 30%–40% on average compared with that using the radial gravity gradient V zz in 250 degrees. Finally, by mutual verification of the analytical error model and numerical simulation, the orders of magnitude from the accuracies of the Earth's gravitational field recovery make no substantial differences based on the radial and three-dimensional gravity gradients, respectively. Therefore, it is feasible to develop in advance a radial cold-atom interferometric gradiometer with a measurement accuracy of 10 −13 /s 2 −10 −15 /s 2 for precisely producing the next-generation GOCE Follow-On Earth gravity field

DIELECTRICALLY-LOADED WAVEGUIDE AS A MICROWAVE UNDULATOR FOR HIGH BRILLANCE X-RAYS AT 45 – 90 KeV

Energy Technology Data Exchange (ETDEWEB)

Kustom, R. L.; Waldschmidt, G.; Nassiri, A.

2017-06-01

The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness xrays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-keV.The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T.

Measurement of X-ray beam emittance using crystal optics at an X-ray undulator beamline

CERN Document Server

Kohmura, Y; Awaji, M; Tanaka, T; Hara, T; Goto, S; Ishikawa, T

2000-01-01

We present a method of using crystal optics to measure the emittance of the X-ray source. Two perfect crystals set in (++) configuration work as a high-resolution collimator. The phase-space diagram (i.e. beam cross-section and angular distribution) could be determined without any assumptions on the light source. When the measurement is done at short wavelength radiation from undulator, the electron beam emittance is larger than the diffraction limit of the X-rays. Therefore, the electron beam emittance could be estimated. The measurement was done with the hard X-rays of 18.5 and 55 keV from an undulator beamline, BL 47XU, of SPring-8. The horizontal emittance of the X-ray beam was estimated to be about 7.6 nmrad, close to the designed electron beam emittance of the storage ring (7 nmrad). Some portions of the instrumental functions, such as the scattering by filters and windows along the beamline and the slight bent of the crystal planes of the monochromator, could not be precisely evaluated, but an upper li...

Propagation of electromagnetic waves in the plasma near electron cyclotron resonance: Undulator-induced transparency

International Nuclear Information System (INIS)

Shvets, G.; Tushentsov, M.; Tokman, M.D.; Kryachko, A.

2005-01-01

Propagation of electromagnetic waves in magnetized plasma near the electron cyclotron frequency can be strongly modified by adding a weak magnetic undulator. For example, both right- and left-hand circularly polarized waves can propagate along the magnetic field without experiencing resonant absorption. This effect of entirely eliminating electron cyclotron heating is referred to as the undulator-induced transparency (UIT) of the plasma, and is the classical equivalent of the well-known quantum mechanical effect of electromagnetically induced transparency. The basics of UIT are reviewed, and various ways in which UIT can be utilized to achieve exotic propagation properties of electromagnetic waves in plasmas are discussed. For example, UIT can dramatically slow down the waves' group velocity, resulting in the extreme compression of the wave energy in the plasma. Compressed waves are polarized along the propagation direction, and can be used for synchronous electron or ion acceleration. Strong coupling between the two wave helicities are explored to impart the waves with high group velocities ∂ω/∂k for vanishing wave numbers k. Cross-helicity coupling for realistic density and magnetic field profiles are examined using a linearized fluid code, particle-in-cell simulations, and ray-tracing WKB calculations

Towards the Selection of an Optimal Global Geopotential Model for the Computation of the Long-Wavelength Contribution: A Case Study of Ghana

Directory of Open Access Journals (Sweden)

Caleb Iddissah Yakubu

2017-11-01

Full Text Available The selection of a global geopotential model (GGM for modeling the long-wavelength for geoid computation is imperative not only because of the plethora of GGMs available but more importantly because it influences the accuracy of a geoid model. In this study, we propose using the Gaussian averaging function for selecting an optimal GGM and degree and order (d/o for the remove-compute-restore technique as a replacement for the direct comparison of terrestrial gravity anomalies and GGM anomalies, because ground data and GGM have different frequencies. Overall, EGM2008 performed better than all the tested GGMs and at an optimal d/o of 222. We verified the results by computing geoid models using Heck and Grüninger’s modification and validated them against GPS/trigonometric data. The results of the validation were consistent with those of the averaging process with EGM2008 giving the smallest standard deviation of 0.457 m at d/o 222, resulting in an 8% improvement over the previous geoid model. In addition, this geoid model, the Ghanaian Gravimetric Geoid 2017 (GGG 2017 may be used to replace second-order class II leveling, with an expected error of 6.8 mm/km for baselines ranging from 20 to 225 km.

Beamline 9.0.1 - a high-resolution undulator beamline for gas-phase spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Bozek, J.D.; Heimann, P.A.; Mossessian, D. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

1997-04-01

Beamline 9.0.1 at the Advanced Light Source is an undulator beamline with a Spherical Grating Monochromator (SGM) which provides very high resolution and flux over the photon energy range 20-320eV. The beamline has been used primarily by the atomic and molecular science community to conduct spectroscopy experiments using electron, ion and fluorescence photon detection. A description of the beamline and its performance will be provided in this abstract.

Thermo-mechanical analysis of the white-beam slits for an undulator beamline at the Advanced Photon Source

International Nuclear Information System (INIS)

Nian, H.L.T.; Shu, D.; Kuzay, T.M.

1994-01-01

A set of precision horizontal and vertical white-beam slits has been designed for an undulator beamline at the Advanced Photon Source. Due to the powerful x-ray heat flux emitted by the undulator, it is difficult to control the thermal distortion within the desired range of 1-2 microns. We analyzed many conceptual designs in an attempt to minimize the thermal distortion of the slits. Even with 1-mm-thick, low-Z material (graphite) coated on the heating surface of a traditional slit, the maximum thermal distortion is over 25 microns. A three-piece slit was then designed to satisfy the requirements. It consists of one large block, two tungsten knife edges, and an OFHC cooling tube (filled with copper mesh) brazed inside the large block. The thermal distortion at the knife edges of this three-piece slit has a relative displacement of less than 2 microns

Online monitoring of absorbed dose in undulator magnets with RADFET dosimeters at FERMI@Elettra

International Nuclear Information System (INIS)

Fröhlich, L.; Casarin, K.; Quai, E.; Holmes-Siedle, A.; Severgnini, M.; Vidimari, R.

2013-01-01

The FERMI@Elettra free-electron laser, based on a 1.3 GeV electron linac, requires the monitoring of radiation doses up to a few kGy for the protection of sensitive equipment such as permanent magnet undulators. A new dosimetry system DOSFET-L01, employing an array of RADFETs spread throughout the accelerator, was developed. So far, the system has performed flawlessly for almost two years, taking one dose reading per minute around the clock. The REM RFT-300 sensors were set in zero-bias mode, i.e. with all electrodes grounded during exposure. This choice of mode allows the measurement of a high range of integrated doses – up to a few kGy. The paper describes the new read-out system and its application, calibration measurements in cobalt-60 and 6 MeV bremsstrahlung radiation sources giving rise to a novel response function, and new data on “fade” under the zero-bias mode of use for over 300 days at room temperature. Regular readings from 28 RADFETs placed within seven undulators over the first 20 months of operation of the accelerator demonstrate how the system tracks and locates periods of high and low dose rate and thereby contributes to the protection from beam loss. The readings from the RADFET system are found to be in good agreement with Gafchromic EBT2 film dosimeters. Based on the results reported, the choice of bias mode may be revised so as to reduce fade and improve the accuracy conferred by a positive-bias mode. -- Highlights: ► We developed a system for online dosimetry with RADFET sensors under zero bias. ► The system is calibrated for doses up to 10 kGy with REM RFT-300 sensors. ► We collected data on fade for over 300 days from irradiation. ► We present undulator dose measurements for 20 months of operation of FERMI@Elettra. ► Dose measurements are in good agreement with chemical film dosimeters

Observation of undulation motion of lipid bilayers by neutron spin echo

International Nuclear Information System (INIS)

Yamada, Norifumi L.; Seto, Hideki; Hishida, Mafumi

2010-01-01

Aqueous solutions of synthesized phospholipids have been well investigated as model biomembranes. These lipids usually self-assemble into regular stacks of bilayers with a characteristic repeat distance on the order of nm, whereas real biomembrane exist as single bilayers. The key phenomenon in understanding the formation of single isolated bilayers in 'unbinding' of lipid bilayers, in which the inter-bilayer distance of lipid bilayers diverges by the steric interaction due to the membrane undulation. In this paper, we show some results of neutron spin-echo (NSE) experiments to investigate the effect of the steric interaction on unbinding and related phenomena. (author)

CSEM-steel hybrid wiggler/undulator magnetic field studies

International Nuclear Information System (INIS)

Halbach, K.; Hoyer, E.; Marks, S.; Plate, D.; Shuman, D.

1985-05-01

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 place 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

Radiation emission at channeling of electrons in a strained layer Si1-xGex undulator crystal

DEFF Research Database (Denmark)

Backe, H.; Krambrich, D.; Lauth, W.

2013-01-01

ML source. Spectra taken at the beam energy of 270 MeV at channeling in the undulating (110) planes exhibit a broad excess yield around the theoretically expected photon energies of 0.069 MeV, as compared with a flat silicon reference crystal. Model calculations on the basis of synchrotron-like radiation...

A non-destructive electron beam diagnostic for a SASE FEL using coherent off-axis undulator radiation

CERN Document Server

Neuman, C P; Barnett, G A; Madey, J M J; O'Shea, P G

1999-01-01

We show that by observing coherent off-axis undulator radiation (COUR) from a short diagnostic wiggler, it may be possible to determine the length and structure of a short electron bunch. Typically the on-axis undulator radiation is incoherent, but at angles of a few degrees, the wavelength of the emitted radiation may be comparable to the length of a short electron bunch, and thus coherence effects emerge. Due to such coherence effects, the intensity of the emitted radiation may change by up to a factor of 10 sup 9 as the angle of observation is increased. The radiation becomes coherent in a way which depends on the length and structure of the electron bunch. Observing COUR disturbs the electron bunch negligibly. Thus, COUR can be used as a non-destructive diagnostic which would allow for optimization of FEL performance while an FEL is operating. Such a diagnostic could be used for proposed SASE FELs, which use short electron bunches. We present two methods to describe the theory for COUR, and we use these m...

Theoretical computation of the polarization characteristics of an X-ray free-electron laser with planar undulator

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2015-02-01

We show that radiation pulses from an X-ray Free-Electron Laser (XFEL) with a planar undulator, which are mainly polarized in the horizontal direction, exhibit a suppression of the vertical polarization component of the power at least by a factor λ 2 w /(4πL g ) 2 , where λ w is the length of the undulator period and L g is the FEL field gain length. We illustrate this fact by examining the XFEL operation under the steady state assumption. In our calculations we considered only resonance terms: in fact, non resonance terms are suppressed by a factor λ 3 w /(4πL g ) 3 and can be neglected. While finding a situation for making quantitative comparison between analytical and experimental results may not be straightforward, the qualitative aspects of the suppression of the vertical polarization rate at XFELs should be easy to observe. We remark that our exact results can potentially be useful to developers of new generation FEL codes for cross-checking their results.

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

CERN Document Server

Reiche, Sven; Emma, Paul; Fawley, William M; Huang, Zhirong; Nuhn, Heinz-Dieter; Stupakov, Gennady

2005-01-01

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 PARMELA 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 ...

Coherent x-rays and vacuum-ultraviolet radiation from storage-ring-based undulators and free electron lasers

International Nuclear Information System (INIS)

Kim, K.J.

1984-12-01

High-brightness electron storage rings and permanent-magnet technology provide a basis for the development of coherent radiation in the 10- to 1000-A (xuv) spectral range. The most assured route to the production of coherent x-rays and vuv is the simple interaction between properly constrained relativistic electrons and permanent-magnet undulators, a subject that is already well understood and where technology is well advanced. Other techniques are less well developed, but with increasing degrees of technical challenge they will provide additional coherence properties. Transverse optical klystrons (TOKs) provide an opportunity for additional coherence at certain harmonics of longer-wavelength lasers. Free electron lasers (FELs) extend coherence capabilities substantially through two possible routes: one is the development of suitable mirror coatings. Both FEL techniques would provide vuv radiation and soft x rays with extremely narrow spectral content. Research on all of these techniques (undulators, TOKs, and FELs) is possible in a single facility based on a high-brightness electron storage ring, referred to herein as a Coherent xuv Facility (CXF). Individual items from the report were prepared separately for the data base

Magnetic field measurements of the harmonic generation FEL superconducting undulator at BNL-NSLS

International Nuclear Information System (INIS)

Solomon, L.; Graves, W.S.; Lehrman, I.

1994-01-01

A three stage superconducting undulator (modulator, dispersive section, and radiator) is under construction at Brookhaven National Laboratory. Sections of the radiator, consisting of 25cm long steel yokes, each with 18mm period, 0.54 Tesla field, and 8.6mm gap are under test. The magnetic measurements and operational characteristics of the magnet are discussed. Measurement results and analysis are presented, with emphasis on the integrated field quality. The magnet winding and the effects of the various trims are discussed

Measurement of X-ray beam emittance using crystal optics at an X-ray undulator beamline

International Nuclear Information System (INIS)

Kohmura, Yoshiki; Suzuki, Yoshio; Awaji, Mitsuhiro; Tanaka, Takashi; Hara, Toru; Goto, Shunji; Ishikawa, Tetsuya

2000-01-01

We present a method of using crystal optics to measure the emittance of the X-ray source. Two perfect crystals set in (++) configuration work as a high-resolution collimator. The phase-space diagram (i.e. beam cross-section and angular distribution) could be determined without any assumptions on the light source. When the measurement is done at short wavelength radiation from undulator, the electron beam emittance is larger than the diffraction limit of the X-rays. Therefore, the electron beam emittance could be estimated. The measurement was done with the hard X-rays of 18.5 and 55 keV from an undulator beamline, BL 47XU, of SPring-8. The horizontal emittance of the X-ray beam was estimated to be about 7.6 nmrad, close to the designed electron beam emittance of the storage ring (7 nmrad). Some portions of the instrumental functions, such as the scattering by filters and windows along the beamline and the slight bent of the crystal planes of the monochromator, could not be precisely evaluated, but an upper limit for the vertical emittance of the electron beam could be obtained as 0.14 nmrad

An electromagnetic helical undulator for polarized X-rays

International Nuclear Information System (INIS)

Gluskin, E.; Vinokurov, N.; Tcheskidov, V.; Medvedko, A.; Evtushenko, Y.; Kolomogorov, V.; Vobly, P.; Antokhin, E.; Ivanov, P.; Vasserman, I. B.; Trakhtenberg, E. M.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Makarov, O.; Moog, E. R.

1999-01-01

Linearly and circularly polarized x-rays have been very successfully applied to the study of the properties of materials. Many applications can benefit from the availability of energy-turnable, high-brilliance x-ray beams with adjustable polarization properties. A helical undulator that can generate beams of variable (linear to circular) polarization has been designed and built by the Budker Institute of Nuclear Physics and the Advanced Photon Source. The first harmonic of this 12.8-cm-period device will cover the energy range from 0.4 keV to 3.5 keV. An important feature of this fully electromagnetic device is that it will allow one to generate 100% horizontally (K x =O)or vertically (K y =O) plane-polarized radiation, which will enable many experiments otherwise not technically feasible. With symmetric deflection parameters (K x =K y ), the on-axis radiation will be circularly polarized, with a user-selectable handedness. The polarization can be changed at rates up to 10 Hz

Comparison of remove-compute-restore and least squares modification of Stokes' formula techniques to quasi-geoid determination over the Auvergne test area

DEFF Research Database (Denmark)

Yildiz, H.; Forsberg, René; Ågren, J.

2012-01-01

The remove-compute-restore (RCR) technique for regional geoid determination implies that both topography and low-degree global geopotential model signals are removed before computation and restored after Stokes' integration or Least Squares Collocation (LSC) solution. The Least Squares Modification...... area. All methods showed a reasonable agreement with GPS-levelling data, in the order of a 3-3.5 cm in the central region having relatively smooth topography, which is consistent with the accuracies of GPS and levelling. When a 1-parameter fit is used, the FFT method using kernel modification performs...

Soft x-ray spectroscopy undulator beamline at the Advanced Photon Source

Energy Technology Data Exchange (ETDEWEB)

Randall, K.J.; Xu, Z.; Moore, J.F.; Gluskin, E.

1997-09-01

Construction of the high-resolution soft x ray spectroscopy undulator beamline, 2ID-C, at the Advanced Photon Source (APS) has been completed. The beamline, one of two soft x ray beamlines at the APS, will cover the photon energy range from 500 to 3,000 eV, with a maximum resolving power between 7,000 and 14,000. The optical design is based on a spherical grating monochromator (SGM) giving both high resolution and high flux throughput. Photon flux is calculated to be approximately 10{sup 12}--10{sup 13} photons per second with a beam size of approximately 1 x 1 mm{sup 2} at the sample.

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

Science.gov (United States)

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.

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

CERN Document Server

Arnold, N D; Banks, G; Bechtold, R; Beczek, K; Benson, C; Berg, S; Berg, W; Biedron, S G; Biggs, J A; Boerste, K; Borland, M; 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, Roger 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 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; 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; Knott, M; Koldenhoven, R J; Labuda, S; Laird, R; Lang, J; Lenkszus, F R; Lessner, E S; Lewellen, J W; Li, Y; Lill, R M; Lumpkin, Alex 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; 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, Vadim; Sarkar, S; Scapino, J C; Schröder, 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; 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

2001-01-01

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.

Measurement of the positron polarization at an helical undulator based positron source for the international linear collider ILC. The E-166 experiment at SLAC

Energy Technology Data Exchange (ETDEWEB)

Karim, Laihem

2008-06-05

A helical undulator based polarized positron source is forseen at a future International Linear Collider (ILC). The E-166 experiment has tested this scheme using a one meter long, short-period, pulsed helical undulator installed in the Final Focus Test Beam (FFTB) at SLAC. A low-emittance 46.6 GeV electron beam passing through this undulator generated circularly polarized photons with energies up to about 8 MeV. The generated photons of several MeV with circular polarization are then converted in a relatively thin target to generate longitudinally polarized positrons. Measurements of the positron polarization have been performed at 5 different energies of the positrons. In addition electron polarization has been determined for one energy point. For a comparison of the measured asymmetries with the expectations detailed simulations were necessary. This required upgrading GEANT4 to include the dominant polarization dependent interactions of electrons, positrons and photons in matter. The measured polarization of the positrons agrees with the expectations and is for the energy point with the highest polarization at 6MeV about 80%. (orig.)

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

Science.gov (United States)

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

Coupling impedance of an in-vacuum undulator: Measurement, simulation, and analytical estimation

Science.gov (United States)

Smaluk, Victor; Fielder, Richard; Blednykh, Alexei; Rehm, Guenther; Bartolini, Riccardo

2014-07-01

One of the important issues of the in-vacuum undulator design is the coupling impedance of the vacuum chamber, which includes tapered transitions with variable gap size. To get complete and reliable information on the impedance, analytical estimate, numerical simulations and beam-based measurements have been performed at Diamond Light Source, a forthcoming upgrade of which includes introducing additional insertion device (ID) straights. The impedance of an already existing ID vessel geometrically similar to the new one has been measured using the orbit bump method. The measurement results in comparison with analytical estimations and numerical simulations are discussed in this paper.

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

Science.gov (United States)

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.

Effects of undulators on the ALS: The early work on the LBL [Lawrence Berkeley Laboratory

International Nuclear Information System (INIS)

Jackson, A.

1988-05-01

In this paper we describe the early work carried out at LBL on the consequences of installing insertion devices (wigglers and undulators) on the beam dynamics of the ALS. This included analytical and tracking studies, and led to an insight to the reasons behind the predicted reduction in dynamic aperture. For completeness, a description of the unperturbed storage ring characteristics are also given. 3 refs., 16 figs., 2 tabs

Ultra-wide-band accumulation of coherent undulator synchrotron radiation in a resonating cavity

Directory of Open Access Journals (Sweden)

Y. H. Seo

2011-06-01

Full Text Available Cavity accumulation of coherent undulator synchrotron radiation emitted by a train of periodic electron bunches is investigated. Phase-matching conditions for accumulation of radiation emitted by successive bunches are analyzed and numerically confirmed. While the coherent emission of a single bunch is optimal at grazing resonance, the accumulated radiation targeted at the upper resonant frequency of the waveguide mode is found to have much broader bandwidth and higher efficiency as the resonance steps away from the grazing condition. Numerical results confirm that stimulated superradiance is responsible for the accumulated radiation.

Undulating tubular liposomes through incorporation of a synthetic skin ceramide into phospholipid bilayers.

Science.gov (United States)

Xu, Peng; Tan, Grace; Zhou, Jia; He, Jibao; Lawson, Louise B; McPherson, Gary L; John, Vijay T

2009-09-15

Nonspherical liposomes were prepared by doping L-alpha-phosphatidylcholine (PC) with ceramide VI (a skin lipid). Cryo-transmission electron microscopy shows the liposome shape changing from spherical to an undulating tubular morphology, when the amount of ceramide VI is increased. The formation of tubular liposomes is energetically favorable and is attributed to the association of ceramide VI with PC creating regions of lower curvature. Since ceramides are the major component of skin lipids in the stratum corneum, tubular liposomes containing ceramide may potentially serve as self-enhanced nanocarriers for transdermal delivery.

A non-destructive electron beam diagnostic for a SASE FEL using coherent off-axis undulator radiation

International Nuclear Information System (INIS)

Neuman, C.P.; Ponds, M.L.; Barnett, G.A.; Madey, J.M.J.; O'Shea, P.G.

1999-01-01

We show that by observing coherent off-axis undulator radiation (COUR) from a short diagnostic wiggler, it may be possible to determine the length and structure of a short electron bunch. Typically the on-axis undulator radiation is incoherent, but at angles of a few degrees, the wavelength of the emitted radiation may be comparable to the length of a short electron bunch, and thus coherence effects emerge. Due to such coherence effects, the intensity of the emitted radiation may change by up to a factor of 10 9 as the angle of observation is increased. The radiation becomes coherent in a way which depends on the length and structure of the electron bunch. Observing COUR disturbs the electron bunch negligibly. Thus, COUR can be used as a non-destructive diagnostic which would allow for optimization of FEL performance while an FEL is operating. Such a diagnostic could be used for proposed SASE FELs, which use short electron bunches. We present two methods to describe the theory for COUR, and we use these methods to calculate the expected outcome of a COUR experiment. We propose an experiment to demonstrate COUR effects and their applications to SASE FELs

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

International Nuclear Information System (INIS)

Bane, Karl L.F.; Emma, Paul; Huang, Heinz-Dieter Nuhn; Stupakov, Gennady; Fawley, William M.; Reiche, Sven

2005-01-01

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., ∼ 20 0fs). To study the 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

Coupling impedance of an in-vacuum undulator: Measurement, simulation, and analytical estimation

Directory of Open Access Journals (Sweden)

Victor Smaluk

2014-07-01

Full Text Available One of the important issues of the in-vacuum undulator design is the coupling impedance of the vacuum chamber, which includes tapered transitions with variable gap size. To get complete and reliable information on the impedance, analytical estimate, numerical simulations and beam-based measurements have been performed at Diamond Light Source, a forthcoming upgrade of which includes introducing additional insertion device (ID straights. The impedance of an already existing ID vessel geometrically similar to the new one has been measured using the orbit bump method. The measurement results in comparison with analytical estimations and numerical simulations are discussed in this paper.

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

Science.gov (United States)

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.

Development of a superconducting elliptically polarized undulator

International Nuclear Information System (INIS)

Chen, S D; Liang, K S; Jan, J C; Hwang, C S

2010-01-01

A superconducting, elliptically polarized undulator (SEPU24) with a period of length 24 mm was developed to provide first-harmonic photons from a 0.8 GeV storage ring for extreme-ultraviolet (EUV) lithography experiment. In SEPU24, two layers of a magnet array structure - with and without rotated magnet arrays - are combined to generate a helical field that provides radiation with wavelength 13.5 nm in the in-band energy. The arrays of iron and aluminium poles were wound with a racetrack coil vertically as for the magnet pole array. The elliptical field is created when the up and down magnet-pole arrays pass excitation currents in alternate directions. SEPU24 is designed with a magnet of gap 6.8 mm, yielding magnetic flux density B x =B z =0.61 T of the helical field. A prototype magnet was fabricated with a diode for quench protection, and assembled in a test dewar to test the magnet performance. A cryogenic Hall-probe system with a precise linear stage was used to measure the distribution of the magnetic field. We describe the design concept and algorithm, the engineering design, the calculation of the magnetic field, the construction and testing of the 10-pole prototype magnet and related issues.

Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin: New constraints on breakup and early spreading history between India and Antarctica

Digital Repository Service at National Institute of Oceanography (India)

Krishna, K.S.; Michael, L.; Bhattacharyya, R.; Majumdar, T.J.

the anomalies. Since the magnetic anomalies in the western Enderby Basin have lower amplitude, Gaina et al. (2007) could not identify the anomalies with confidence and found difficulty to correlate the spreading history with that of the central and eastern... Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin – new constraints on breakup and early spreading history between India and Antarctica K.S. Krishna*, Laju Michael National Institute of Oceanography, Council...

A zone plate soft x-ray microscope using monochromatized undulator radiation at the beamline NE1B of the TRISTAN Accumulation Ring

International Nuclear Information System (INIS)

Wang, J.; Kagoshima, Y.; Miyahara, T.; Ando, M.; Aoki, S.; Anderson, E.; Attwood, D.; Kern, D.

1995-01-01

A soft x-ray microscope has been developed at the beamline NE1B of the 6.5-GeV TRISTAN Accumulation Ring (AR). It makes use of undulator radiation as its source and a zone plate with the outermost zone width of 50 nm as its imaging element. It has two main features. First, the undulator radiation is monochromatized by a grazing incidence grating monochromator to match to the monochromaticity requirement of the zone plate. Second, a visible light prefocus unit consisting of two objectives has been designed and installed in the x-ray microscope. The x-ray optical system of the microscope can be adjusted easily, quickly, and precisely by using this unit. The microscope can resolve 55-nm lines and spaces in a zone plate test pattern

Lithospheric structure of southern Indian shield and adjoining oceans: integrated modelling of topography, gravity, geoid and heat flow data

Science.gov (United States)

Kumar, Niraj; Zeyen, H.; Singh, A. P.; Singh, B.

2013-07-01

For the present 2-D lithospheric density modelling, we selected three geotransects of more than 1000 km in length each crossing the southern Indian shield, south of 16°N, in N-S and E-W directions. The model is based on the assumption of local isostatic equilibrium and is constrained by the topography, gravity and geoid anomalies, by geothermal data, and where available by seismic data. Our integrated modelling approach reveals a crustal configuration with the Moho depth varying from ˜40 km beneath the Dharwar Craton, and ˜39 km beneath the Southern Granulite Terrane to about 15-20 km beneath the adjoining oceans. The lithospheric thickness varies significantly along the three profiles from ˜70-100 km under the adjoining oceans to ˜130-135 km under the southern block of Southern Granulite Terrane including Sri Lanka and increasing gradually to ˜165-180 km beneath the northern block of Southern Granulite Terrane and the Dharwar Craton. This step-like lithosphere-asthenosphere boundary (LAB) structure indicates a normal lithospheric thickness beneath the adjoining oceans, the northern block of Southern Granulite Terrane and the Dharwar Craton. The thin lithosphere below the southern block of Southern Granulite Terrane including Sri Lanka is, however, atypical considering its age. Our results suggest that the southern Indian shield as a whole cannot be supported isostatically only by thickened crust; a thin and hot lithosphere beneath the southern block of Southern Granulite Terrane including Sri Lanka is required to explain the high topography, gravity, geoid and crustal temperatures. The widespread thermal perturbation during Pan-African (550 Ma) metamorphism and the breakup of Gondwana during late Cretaceous are proposed as twin cause mechanism for the stretching and/or convective removal of the lower part of lithospheric mantle and its replacement by hotter and lighter asthenosphere in the southern block of Southern Granulite Terrane including Sri Lanka

FEL polarization control studies on Dalian coherent light source

International Nuclear Information System (INIS)

Zhang Tong; Deng Haixiao; Wang Dong; Zhao Zhentang; Zhang Weiqing; Wu Guorong; Dai Dongxu; Yang Xueming

2013-01-01

The polarization switch of a free-electron laser (FEL) is of great importance to the user scientific community. In this paper, we investigate the generation of controllable polarization FEL from two well-known approaches for Dalian coherent light source, i.e., crossed planar undulator and elliptical permanent undulator. In order to perform a fair comparative study, a one-dimensional time-dependent FEL code has been developed, in which the imperfection effects of an elliptical permanent undulator are taken into account. Comprehensive simulation results indicate that the residual beam energy chirp and the intrinsic FEL gain may contribute to the degradation of the polarization performance for the crossed planar undulator. The elliptical permanent undulator is not very sensitive to the undulator errors and beam imperfections. Meanwhile, with proper configurations of the main planar undulators and additional elliptical permanent undulator section, circular polarized FEL with pulse energy exceeding 100 μJ could be achieved at Dalian coherent light source. (authors)

Geometric Mechanics Reveals Optimal Complex Terrestrial Undulation Patterns

Science.gov (United States)

Gong, Chaohui; Astley, Henry; Schiebel, Perrin; Dai, Jin; Travers, Matthew; Goldman, Daniel; Choset, Howie; CMU Team; GT Team

Geometric mechanics offers useful tools for intuitively analyzing biological and robotic locomotion. However, utility of these tools were previously restricted to systems that have only two internal degrees of freedom and in uniform media. We show kinematics of complex locomotors that make intermittent contacts with substrates can be approximated as a linear combination of two shape bases, and can be represented using two variables. Therefore, the tools of geometric mechanics can be used to analyze motions of locomotors with many degrees of freedom. To demonstrate the proposed technique, we present studies on two different types of snake gaits which utilize combinations of waves in the horizontal and vertical planes: sidewinding (in the sidewinder rattlesnake C. cerastes) and lateral undulation (in the desert specialist snake C. occipitalis). C. cerastes moves by generating posteriorly traveling body waves in the horizontal and vertical directions, with a relative phase offset equal to +/-π/2 while C. occipitalismaintains a π/2 offset of a frequency doubled vertical wave. Geometric analysis reveals these coordination patterns enable optimal movement in the two different styles of undulatory terrestrial locomotion. More broadly, these examples demonstrate the utility of geometric mechanics in analyzing realistic biological and robotic locomotion.

Orbit Correction for the Newly Developed Polarization-Switching Undulator

Science.gov (United States)

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.

A water-cooled x-ray monochromator for using off-axis undulator beam

International Nuclear Information System (INIS)

Khounsary, A.; Maser, J.

2000-01-01

Undulator beamlines at third-generation synchrotrons x-ray sources are designed to use the high-brilliance radiation that is contained in the central cone of the generated x-ray beams. The rest of the x-ray beam is often unused. Moreover, in some cases, such as in the zone-plate-based microfocusing beamlines, only a small part of the central radiation cone around the optical axis is used. In this paper, a side-station branch line at the Advanced Photon Source that takes advantage of some of the unused off-axis photons in a microfocusing x-ray beamline is described. Detailed information on the design and analysis of a high-heat-load water-cooled monochromator developed for this beamline is provided

Performance of the undulator based ultraviolet and soft x-ray beamline for catalysis and surface science at National Synchrotron Radiation Laboratory

Energy Technology Data Exchange (ETDEWEB)

Du, Liangliang [University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui 230029 (China); University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230029 (China); Du, Xuewei, E-mail: xwdu@ustc.edu.cn [University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230029 (China); Wei, Shen [University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230029 (China); Li, Chaoyang [China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Pan, Congyuan; Ju, Huanxin [University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230029 (China); Wang, Qiuping, E-mail: qiuping@ustc.edu.cn [University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230029 (China); Zhu, Junfa [University of Science and Technology of China, National Synchrotron Radiation Laboratory, Hefei, Anhui 230029 (China)

2016-12-01

The undulator based ultraviolet and soft x-ray beamline BL11U for catalysis and surface science at National Synchrotron Radiation Laboratory (NSRL) has been under opteration for months and the present performance is described. This beamline utilizes radiation from an in-vacuum undulator, which has 30 magnetic periods with the period length of 40 mm. A varied-line-spacing plane grating monochromator is employed tto cover the photon energy region of 20–600 eV by two gratings with nominal groove densities of 400 llmm and 1200 l/mm respectively. The energy resolution power E/ΔE is measured with a gas ionization chamber and the photon flux is measured by a photodiode. Results show that the resolution power is better than 10,000 at a photon energy of 29.2 eV. And the flux is higher than 1×10{sup 10} phs/s under 300 mA ring beam current for most of the covered photon energy.

Effects of Pre - Season Short - Term Daily Undulating Periodized Training on Muscle Strength and Sprint Performance of Under - 20 Soccer Players

Directory of Open Access Journals (Sweden)

Charles Ricardo L OPES

2015-06-01

Full Text Available The aim of this study was to evaluate the effects of daily undulating training periodization designed for maximal lower limb muscle strength and sprint performance in under - 20 soccer players. Twenty - four male athletes (age = 19.1 ± 1.2 yr; mass = 71.1 ± 6. 8 kg; height = 178.0 ± 0.1 cm participated in four weeks of a daily undulating periodized (DUP training soccer program. During the pre - and post - training periods the subjects performed a one repetition maximum (1 RM half back squat test and a 15 - meter s print. Significant training - induced changes were observed in sprint times (pre = 2.38 ± 0.01 s; post = 2.31 ± 0.02 s and 1 RM tests (pre = 107.0 ± 2.0 kg; post = 128.0 ± 2.2 kg. These results indicate that a DUP program is efficient in promoting positive neuromuscular adaptations in soccer players, even with a short - term preseason training period.

An Energy-Stabilized Varied-Line-Space-Monochromator Undulator Beam Line for PEEM Illumination and Magnetic Circular Dichroism

International Nuclear Information System (INIS)

Warwick, Tony; McKinney, Wayne; Domning, Ed; Doran, Andrew; Padmore, Howard

2006-01-01

A new undulator beam line has been built and commissioned at the Advanced Light Source for illumination of the PEEM3 microscope. The beam line delivers high flux beams over an energy range from C1s through the transition metals to include the M edges of the magnetic rare earth elements. We present details of the optical design, and data on the performance of the zero-order tracking of the photon energy

Nd{sub 2}Fe{sub 14}B and Pr{sub 2}Fe{sub 14}B magnets characterisation and modelling for cryogenic permanent magnet undulator applications

Energy Technology Data Exchange (ETDEWEB)

Benabderrahmane, C., E-mail: chamseddine.benabderrahmane@synchrotron-soleil.fr [Synchrotron SOLEIL, St Aubin (France); Berteaud, P.; Valleau, M.; Kitegi, C.; Tavakoli, K.; Bechu, N.; Mary, A.; Filhol, J.M.; Couprie, M.E. [Synchrotron SOLEIL, St Aubin (France)

2012-03-21

Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE{sub 2}Fe{sub 14}B (Rare Earth based magnets) at cryogenic temperatures for achieving short period high magnetic field. In particular, using Praseodymium instead of Neodymium generally employed for insertion devices avoids limitation due to Spin Reorientation Transition phenomenon. Magnetic properties of magnet samples (Nd{sub 2}Fe{sub 14}B and Pr{sub 2}Fe{sub 14}B) versus temperature have been investigated and applied to a 20 mm period Nd{sub 2}Fe{sub 14}B (BH50) and to a 18 mm period Pr{sub 2}Fe{sub 14}B (CR53) systems. Four period undulators have been built, characterised and compared to the models.

Computation of undulator tuning curves

International Nuclear Information System (INIS)

Dejus, Roger J.

1997-01-01

Computer codes for fast computation of on-axis brilliance tuning curves and flux tuning curves have been developed. They are valid for an ideal device (regular planar device or a helical device) using the Bessel function formalism. The effects of the particle beam emittance and the beam energy spread on the spectrum are taken into account. The applicability of the codes and the importance of magnetic field errors of real insertion devices are addressed. The validity of the codes has been experimentally verified at the APS and observed discrepancies are in agreement with predicted reduction of intensities due to magnetic field errors. The codes are distributed as part of the graphical user interface XOP (X-ray OPtics utilities), which simplifies execution and viewing of the results

Modeling and measurement of the ALS U5 undulator end magnetic structures

International Nuclear Information System (INIS)

Humphries, D.; Halbach, K.; Hoyer, E.; Kincaid, B.; Marks, S.; Schlueter, R.

1993-05-01

The end structures for the ALS U5.0 undulators utilize a system of dual permanent magnet rotors intended to establish gap independent field performance. They may also be used for tuning of the first and second magnetic field integrals of these devices. The behavior of these structures has been studied by means of a two dimensional modeling with the POISSON Group of computer codes. A parametric study of the magnetic field distribution and first and second integrals of the fields has been conducted. In parallel, magnetic measurements of the final completed structures have been performed using an automated Hall probe measurement system. Results of the modeling and measurements are compared. Implications for tuning of the ends of the devices within the context of the electron beam parameters of the ALS are discussed

CHESS upgrade with compact undulator magnets: Operating experience and first results

Energy Technology Data Exchange (ETDEWEB)

Temnykh, A., E-mail: abt6@cornell.edu; Dale, D.; Fontes, E.; Lyndaker, A.; Li, Y.; Ruff, J.; Revesz, P.; Woll, A. [Cornell High Energy Synchrotron Source (United States)

2016-07-27

In November 2014 two in-air 1.5 m CHESS Compact Undulator (CCU) magnets built by KYMA S.R.l. were installed in Cornell Electron Storage Ring (CESR) in canted arrangement and after few days of commissioning their regular operation started. CCU magnets are compact, lightweight and cost efficient devices. They have very stable magnetic field integrals independent of deflection parameter value. This feature greatly simplifies the storage ring operation. The CCU concept was developed at Cornell in 2011 and the first 1 m in-vacuum CCU magnet was beam-tested in 2012. The article presents CCU concept and some details of the design. It describes also the layout of CCUs installation in CESR, their performance and characteristics. The current status of operation and future plans are discussed as well. Presently, at CHESS two CCU magnets provide radiation for 5 out of 11 experimental stations.

CHESS upgrade with compact undulator magnets: Operating experience and first results

International Nuclear Information System (INIS)

Temnykh, A.; Dale, D.; Fontes, E.; Lyndaker, A.; Li, Y.; Ruff, J.; Revesz, P.; Woll, A.

2016-01-01

In November 2014 two in-air 1.5 m CHESS Compact Undulator (CCU) magnets built by KYMA S.R.l. were installed in Cornell Electron Storage Ring (CESR) in canted arrangement and after few days of commissioning their regular operation started. CCU magnets are compact, lightweight and cost efficient devices. They have very stable magnetic field integrals independent of deflection parameter value. This feature greatly simplifies the storage ring operation. The CCU concept was developed at Cornell in 2011 and the first 1 m in-vacuum CCU magnet was beam-tested in 2012. The article presents CCU concept and some details of the design. It describes also the layout of CCUs installation in CESR, their performance and characteristics. The current status of operation and future plans are discussed as well. Presently, at CHESS two CCU magnets provide radiation for 5 out of 11 experimental stations.

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

International Nuclear Information System (INIS)

Nian, H.L.T.; Kuzay, T.M.; Collins, J.; Shu, D.; Benson, C.; Dejus, R.

1996-01-01

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 to 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

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

International Nuclear Information System (INIS)

Waldschmidt, G. J.

1998-01-01

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

Spontaneous Radiation Background Calculation for LCLS

CERN Document Server

Reiche, Sven

2004-01-01

The intensity of undulator radiation, not amplified by the FEL interaction, can be larger than the maximum FEL signal in the case of an X-ray FEL. In the commissioning of a SASE FEL it is essential to extract an amplified signal early to diagnose eventual misalignment of undulator modules or errors in the undulator field strength. We developed a numerical code to calculate the radiation pattern at any position behind a multi-segmented undulator with arbitrary spacing and field profiles. The output can be run through numerical spatial and frequency filters to model the radiation beam transport and diagnostic. In this presentation we estimate the expected background signal for the FEL diagnostic and at what point along the undulator the FEL signal can be separated from the background. We also discusses how much information on the undulator field and alignment can be obtained from the incoherent radiation signal itself.

Estimates of the topographic uplift of the Southern African Plateau from the African Superswell through petrologically-consistent thermo-chemical modelling of the geoid, SHF, Rayleigh and Love dispersion curves and MT data

Science.gov (United States)

Jones, Alan G.; Afonso, Juan Carlos; Fullea, Javier

2015-04-01

The deep mantle African Superswell is thought to cause up to 500 m of the uplift of the Southern African Plateau. We investigate this phenomenon through stochastic thermo-chemical inversion modelling of the geoid, surface heat flow, Rayleigh and Love dispersion curves and MT data, in a manner that is fully petrologically-consistent. We invert for a three layer crustal velocity, density and thermal structure, but assume the resistivity layering (based on prior inversion of the MT data alone). Inversions are performed using an improved Delayed Rejection and Adaptive Metropolis (DRAM) type Markov chain Monte Carlo (MCMC) algorithm. We demonstrate that a single layer lithosphere can fit most of the data, but not the MT responses. We further demonstrate that modelling the seismic data alone, without the constraint of requiring reasonable oxide chemistry or of fitting the geoid, permits wildly acceptable elevations and with very poorly defined lithosphere-asthenosphere boundary (LAB). We parameterise the lithosphere into three layers, and bound the permitted oxide chemistry of each layer consistent with known chemical layering. We find acceptable models, from 5 million tested in each case, that fit all responses and yield a posteriori elevation distributions centred on 900-950 m, suggesting dynamic support from the lower mantle of some 400 m.

Gravity Field Parameter Estimation Using QR Factorization

Science.gov (United States)

Klokocnik, J.; Wagner, C. A.; McAdoo, D.; Kostelecky, J.; Bezdek, A.; Novak, P.; Gruber, C.; Marty, J.; Bruinsma, S. L.; Gratton, S.; Balmino, G.; Baboulin, M.

2007-12-01

This study compares the accuracy of the estimated geopotential coefficients when QR factorization is used instead of the classical method applied at our institute, namely the generation of normal equations that are solved by means of Cholesky decomposition. The objective is to evaluate the gain in numerical precision, which is obtained at considerable extra cost in terms of computer resources. Therefore, a significant increase in precision must be realized in order to justify the additional cost. Numerical simulations were done in order to examine the performance of both solution methods. Reference gravity gradients were simulated, using the EIGEN-GL04C gravity field model to degree and order 300, every 3 seconds along a near-circular, polar orbit at 250 km altitude. The simulation spanned a total of 60 days. A polar orbit was selected in this simulation in order to avoid the 'polar gap' problem, which causes inaccurate estimation of the low-order spherical harmonic coefficients. Regularization is required in that case (e.g., the GOCE mission), which is not the subject of the present study. The simulated gravity gradients, to which white noise was added, were then processed with the GINS software package, applying EIGEN-CG03 as the background gravity field model, followed either by the usual normal equation computation or using the QR approach for incremental linear least squares. The accuracy assessment of the gravity field recovery consists in computing the median error degree-variance spectra, accumulated geoid errors, geoid errors due to individual coefficients, and geoid errors calculated on a global grid. The performance, in terms of memory usage, required disk space, and CPU time, of the QR versus the normal equation approach is also evaluated.

Beam Diagnostics for Laser Undulator Based on Compton Backward Scattering

CERN Document Server

Kuroda, R

2005-01-01

A compact soft X-ray source is required in various research fields such as material and biological science. The laser undulator based on Compton backward scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. It is performed in a water window region (250eV - 500 eV) using the interaction between 1047 nm Nd:YLF laser (10ps FWHM) and about 5 MeV high quality electron beam (10ps FWHM) generated from rf gun system. The range of X-ray energy in the water window region has K-shell absorption edges of Oxygen, Carbon and Nitrogen, which mainly constitute of living body. Since the absorption coefficient of water is much smaller than the protein's coefficient in this range, a dehydration of the specimens is not necessary. To generate the soft X-ray pulse stably, the electron beam diagnostics have been developed such as the emittance measurement using double slit scan technique, the bunch length measurement using two frequency analysis technique. In this confere...

Planar undulator motion excited by a fixed traveling wave. Quasiperiodic averaging normal forms and the FEL pendulum

Energy Technology Data Exchange (ETDEWEB)

Ellison, James A.; Heinemann, Klaus [New Mexico Univ., Albuquerque, NM (United States). Dept. of Mathematics and Statistics; Vogt, Mathias [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Gooden, Matthew [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics

2013-03-15

We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the X-Ray FEL regime. Our starting point is the 6D Lorentz system, which allows planar motions, and we examine this dynamical system as the wave length {lambda} of the traveling wave varies. By scalings and transformations the 6D system is reduced, without approximation, to a 2D system in a form for a rigorous asymptotic analysis using the Method of Averaging (MoA), a long time perturbation theory. The two dependent variables are a scaled energy deviation and a generalization of the so- called ponderomotive phase. As {lambda} varies the system passes through resonant and nonresonant (NR) zones and we develop NR and near-to-resonant (NtoR) MoA normal form approximations. The NtoR normal forms contain a parameter which measures the distance from a resonance. For a special initial condition, for the planar motion and on resonance, the NtoR normal form reduces to the well known FEL pendulum system. We then state and prove NR and NtoR first-order averaging theorems which give explicit error bounds for the normal form approximations. We prove the theorems in great detail, giving the interested reader a tutorial on mathematically rigorous perturbation theory in a context where the proofs are easily understood. The proofs are novel in that they do not use a near identity transformation and they use a system of differential inequalities. The NR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the planar prob- lem has not been analyzed with the generality we aspire to here nor has the standard FEL pendulum system been derived with associated error bounds as we do here. We briefly discuss the low gain theory in light of our NtoR normal form. Our mathematical treatment of the noncollective FEL beam dynamics problem in

Planar undulator motion excited by a fixed traveling wave. Quasiperiodic averaging normal forms and the FEL pendulum

International Nuclear Information System (INIS)

Ellison, James A.; Heinemann, Klaus; Gooden, Matthew

2013-03-01

We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the X-Ray FEL regime. Our starting point is the 6D Lorentz system, which allows planar motions, and we examine this dynamical system as the wave length λ of the traveling wave varies. By scalings and transformations the 6D system is reduced, without approximation, to a 2D system in a form for a rigorous asymptotic analysis using the Method of Averaging (MoA), a long time perturbation theory. The two dependent variables are a scaled energy deviation and a generalization of the so- called ponderomotive phase. As λ varies the system passes through resonant and nonresonant (NR) zones and we develop NR and near-to-resonant (NtoR) MoA normal form approximations. The NtoR normal forms contain a parameter which measures the distance from a resonance. For a special initial condition, for the planar motion and on resonance, the NtoR normal form reduces to the well known FEL pendulum system. We then state and prove NR and NtoR first-order averaging theorems which give explicit error bounds for the normal form approximations. We prove the theorems in great detail, giving the interested reader a tutorial on mathematically rigorous perturbation theory in a context where the proofs are easily understood. The proofs are novel in that they do not use a near identity transformation and they use a system of differential inequalities. The NR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the planar prob- lem has not been analyzed with the generality we aspire to here nor has the standard FEL pendulum system been derived with associated error bounds as we do here. We briefly discuss the low gain theory in light of our NtoR normal form. Our mathematical treatment of the noncollective FEL beam dynamics problem in the

Magnetic measurements and tuning of undulators for the APS FEL project

International Nuclear Information System (INIS)

Vasserman, I. B.

1999-01-01

Two insertion device magnetic structures have been prepared for the Advanced Photon Source (APS) FEL project [1]. The magnetic structures are standard APS undulatory, 2.4 m long with a 3.3-cm period. Measurements and tuning of the undulatory have been completed at a magnetic gap of about 9.3 mm, where K is 3.1. Special measurement and tuning techniques were used to satisfy the tight trajectory straightness requirement that the second field integral be less than 3.3 kG-cm 2 . The magnetic field strengths of the undulators must be well matched; this leads to the requirement that the magnetic gap must be controlled to better than 10 microns. Proper phasing between the undulatory is ensured by adjusting the length of the drift space between the undulatory. The drift space length that is needed is strongly affected by the end fields of the magnetic structures. The results of measurements of the magnetic field and calculations of the drift length are provided

Modeling the Salar de Uyuni, Bolivia as an Equipotential Surface of Earth's Gravity Field

Science.gov (United States)

Borsa, Adrian; Bills, Bruce

2004-01-01

The salar de Uyuni is a massive dry salt lake that lies at the lowest point of an internal/drainage basin in the Bolivian Altiplano. Its topography is remarkable for its extraordinary flatness over almost a full degree of latitude and longitude. We surveyed a 54 x 45 km region of the salar with kinematic GPS in September, 2002 and found a topographic range of only 80 cm over the entire surveyed area. Furthermore, the survey revealed distinct surface features with several dominant wavelengths and orientations. Some of these appear to be aligned with orographic features that intersect the salar, leading us to conjecture that they are the surface expression of high-density mountains that have been buried by low-density basin sediments. Over the oceans, a similar correspondence between basin bathymetry and surface topography is exploited to map the seafloor using sea-surface satellite altimetry measurements, with the sea surface following geoid undulations due to the underwater mass distribution. On the salar, annual flooding creates a shallow lake whose surface also lies on a equipotential surface shaped by the distribution of underlying mass. The link to the actual salar surface is via the dissolution and redeposition of salt by the lake waters, which appears to push the system to an equilibrium of constant water depth and the coincidence of the shapes of the lake surface and bottom. To test our hypothesis about the origin of the surface features on the salar, we compare our GPS survey elevations with the equipotential surface generated from local gravity measurements in conjunction with gravity and potential values from the EGM96 global geopotential model. 50% of the variance of the GPS elevations can be explained by equipotential surface undulations from the EGM96 model alone, and an additional 40% is explained by the shorter-wavelength equipotential surface derived from local gravity. We examine the unexplained 10% of elevation variance from the standpoint of

Design and test of a short mockup magnet for the superconducting undulator at the SSRF

Energy Technology Data Exchange (ETDEWEB)

Xu, Jieping, E-mail: jpxu@sinap.ac.cn; Ding, Yi; Cui, Jian; Zhang, Wei; Wang, Hongfei; Yin, Lixin [Department of Mechanical Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)

2016-07-27

A superconducting planar undulator is under development at the Shanghai Synchrotron Radiation Facility (SSRF) to provide the SSRF users with higher photon fluxes at higher photon energies. A 5-period magnet was designed and built for feasibility study. The short mockup magnet is composed of NbTi/Cu winding and low carbon steel former and was tested in a vertical cryocooler-cooled cryostat. The nominal current of 387 A was reached after 2 quenches and the maximum current of 433.2 A was achieved. The magnetic field profile was measured and a peak field of 0.93 T was obtained when stably operating at 400 A.

Radiative interaction of electrons in a short electron bunch moving in an undulator

International Nuclear Information System (INIS)

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

1999-01-01

This paper presents investigations of the longitudinal radiative force in an electron bunch. The model of the electron bunch assumes line density distribution. General formulas are presented for the calculation of the radiative force in the bunch moving along an arbitrary small-angle trajectory. The case of a motion in an undulator (wiggler) has been studied in detail. Analytical solutions are obtained for a rectangular and for a Gaussian bunch shape. It is shown that the rate of the bunch energy loss due to the radiative interaction is equal to the power of the coherent radiation in the far zone. Numerical estimations presented in the paper show that the effects of induced energy spread due to the radiative interaction can be important for free electron lasers operating in the infrared wavelength range

Venus spherical harmonic gravity model to degree and order 60

Science.gov (United States)

Konopliv, Alex S.; Sjogren, William L.

1994-01-01

The Magellan and Pioneer Venus Orbiter radiometric tracking data sets have been combined to produce a 60th degree and order spherical harmonic gravity field. The Magellan data include the high-precision X-band gravity tracking from September 1992 to May 1993 and post-aerobraking data up to January 5, 1994. Gravity models are presented from the application of Kaula's power rule for Venus and an alternative a priori method using surface accelerations. Results are given as vertical gravity acceleration at the reference surface, geoid, vertical Bouguer, and vertical isostatic maps with errors for the vertical gravity and geoid maps included. Correlation of the gravity with topography for the different models is also discussed.

Scheme for simultaneous generation of three-color ten GW-level X-ray pulses from baseline XFEL undulator and multi-user distribution system for XFEL laboratory

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2010-01-01

The baseline design of present XFEL projects only considers the production of a single photon beam at fixed wavelength from each baseline undulator. At variance, the scheme described in this paper considers the simultaneous production of high intensity SASE FEL radiation at three different wavelengths. We present a feasibility study of our scheme, and we make exemplifications with parameters of the baseline SASE2 line of the European XFEL operating in simultaneous mode at 0.05 nm, 0.15 nm and 0.4 nm. Our technique for generating the two colors at 0.05 nm and 0.15 nm is based in essence on a ''fresh bunch'' technique. For the generation of radiation at 0.4 nm we propose to use an ''afterburner'' technique. Implementation of these techniques does not perturb the baseline mode of operation of the SASE2 undulator. The present paper also describes an efficient way to obtain a multi-user facility. It is shown that, although the XFEL photon beam from a given undulator is meant for a single user, movable multilayer X-ray mirrors can be used to serve many users simultaneously. The proposed photon beam distribution system would allow to switch the FEL beam quickly between many experiments in order to make an efficient use of the source. Distribution of photons is achieved on the basis of pulse trains and it is possible to distribute the multicolor photon beam among many independent beam lines, thereby enabling many users to work in parallel with different wavelengths. (orig.)

Error-related brain activity and error awareness in an error classification paradigm.

Science.gov (United States)

Di Gregorio, Francesco; Steinhauser, Marco; Maier, Martin E

2016-10-01

Error-related brain activity has been linked to error detection enabling adaptive behavioral adjustments. However, it is still unclear which role error awareness plays in this process. Here, we show that the error-related negativity (Ne/ERN), an event-related potential reflecting early error monitoring, is dissociable from the degree of error awareness. Participants responded to a target while ignoring two different incongruent distractors. After responding, they indicated whether they had committed an error, and if so, whether they had responded to one or to the other distractor. This error classification paradigm allowed distinguishing partially aware errors, (i.e., errors that were noticed but misclassified) and fully aware errors (i.e., errors that were correctly classified). The Ne/ERN was larger for partially aware errors than for fully aware errors. Whereas this speaks against the idea that the Ne/ERN foreshadows the degree of error awareness, it confirms the prediction of a computational model, which relates the Ne/ERN to post-response conflict. This model predicts that stronger distractor processing - a prerequisite of error classification in our paradigm - leads to lower post-response conflict and thus a smaller Ne/ERN. This implies that the relationship between Ne/ERN and error awareness depends on how error awareness is related to response conflict in a specific task. Our results further indicate that the Ne/ERN but not the degree of error awareness determines adaptive performance adjustments. Taken together, we conclude that the Ne/ERN is dissociable from error awareness and foreshadows adaptive performance adjustments. Our results suggest that the relationship between the Ne/ERN and error awareness is correlative and mediated by response conflict. Copyright © 2016 Elsevier Inc. All rights reserved.

An undulator based high flux and high resolution beamline for atomic, molecular and optical science (AMOS) research at INDUS-2 synchrotron radiation source (SRS)

International Nuclear Information System (INIS)

Das, Asim Kumar; Rajasekhar, B.N.; Sahoo, N.K.

2014-08-01

A dedicated UV-VUV and soft X-ray beamline to provide several new research opportunities in Photon induced processes in the energy range of 6-250 eV for Atomic Molecular and Optical Science (AMOS) research, a domain still less explored both at national as well international level, has been proposed by Atomic and Molecular Physics Division, BARC. This beamline will use a planar permanent magnet (PPM) undulator based on Indus-2 Synchrotron Radiation Source (SRS), a 2.5 GeV third generation electron storage ring at RRCAT, Indore, India and is expected to offer a variety of opportunities for more advanced and sustained investigations for AMOS research. A plane mirror and a toroidal mirror are used as the pre-focusing optics of the AMOS beamline. A varied line spacing plane grating monochromator (VLSPGM) in a converging beam, constant included angle mode containing one toroidal focusing mirror and four interchangeable gratings is to be used to cover the energy range of 6 to 250 eV and obtain resolving powers ∼10 4 and intensity ∼10 12 ph/s at the sample position. A toroidal mirror is used to focus the diverging monochromatic light from the monochromator at a distance of 150 cm with a 1:1 magnification. As the first step towards the beamline optics design, the evaluation of the PPM undulator radiation characteristics relevant to beamline design has been performed using the Indus-2 SRS parameters in the long straight section of the ring, PPM undulator parameters, and the empirical expressions available in literature. The software resources such as XOPS, ESRF, France and SPECTRA, Photon factory, Japan have been used for detailed modelling and verification of the empirical computations. Beamline layout preparation, optimization, imaging performance evaluation, and resolving power calculations for ideal beamline optics are carried out using SHADOWVUI, an extension of XOPS software resource. A new mounting of the optical components in the monochromator has been proposed

Development of Compact Soft X-ray Source Based on Laser Undulator

CERN Document Server

Kuroda, Ryunosuke; Minamiguchi, S; Saitô, T; Ueyama, D; Washio, Masakazu

2004-01-01

A compact soft X-ray source is required in various research fields such as material and biological science. The laser undulator based on backward Compton scattering has been developed as a compact soft X-ray source for the biological observation at Waseda University. It is performed in a water window region (250eV - 500 eV) using the interaction between 1047 nm Nd:YLF laser and 4 MeV high quality electron beam generated from rf gun system. The range of energy in the water window region has K-shell absorption edges of Oxygen, Carbon and Nitrogen, which mainly constitute of living body. Since the absorption coefficient of water is much smaller than the protein’s coefficient in this range, a dehydration of the specimens is not necessary. As a preliminary experiment, about 300 eV X-ray generation was carried out. As next step, soft X-ray optics with zone plate was proposed for Soft X-ray microscopy. In this conference, we will report details and results of the experiment.

OPERATIONAL EXPERIENCE WITH BEAM ABORT SYSTEM FOR SUPERCONDUCTING UNDULATOR QUENCH MITIGATION*

Energy Technology Data Exchange (ETDEWEB)

Harkay, Katherine C.; Dooling, Jeffrey C.; Sajaev, Vadim; Wang, Ju

2017-06-25

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 of 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.

Electronic states of the θ' phase in Cu-Al alloys as compared to C16-CuAl2: Cu Lα emission excited directly by undulator radiation

Science.gov (United States)

Dallera, C.; de Michelis, B.; Puppin, E.; Braicovich, L.; Brookes, N. B.

1996-01-01

The electronic states of the θ' phase formed by thermal aging in the Al-Cu (0.5 at. %) alloy are compared with those in C16-CuAl2, which is the final phase separated at equilibrium. This is done by means of Cu Lα fluorescence spectroscopy. The high brilliance of undulator radiation used as an excitation source is exploited. The spectra are taken using the first harmonic of the undulator at 1.7 keV, with a full width half maximum of ~250 eV. A narrowing of around 0.5 eV of the Cu Lα spectra in the θ' phase is found. This is explained in terms of the differences in the Cu 3d-Cu 3d interaction in the two phases and of the hybridization between Cu 3d and the nearly free-electron-like electrons. The results demonstrate the future possibilities of fluorescence spectroscopy of minority species in inhomogeneous systems.

Temperature Measurements in the Magnetic Measurement Facility

Energy Technology Data Exchange (ETDEWEB)

Wolf, Zachary

2010-12-13

Several key LCLS undulator parameter values depend strongly on temperature primarily because of the permanent magnet material the undulators are constructed with. The undulators will be tuned to have specific parameter values in the Magnetic Measurement Facility (MMF). Consequently, it is necessary for the temperature of the MMF to remain fairly constant. Requirements on undulator temperature have been established. When in use, the undulator temperature will be in the range 20.0 {+-} 0.2 C. In the MMF, the undulator tuning will be done at 20.0 {+-} 0.1 C. For special studies, the MMF temperature set point can be changed to a value between 18 C and 23 C with stability of {+-}0.1 C. In order to ensure that the MMF temperature requirements are met, the MMF must have a system to measure temperatures. The accuracy of the MMF temperature measurement system must be better than the {+-}0.1 C undulator tuning temperature tolerance, and is taken to be {+-}0.01 C. The temperature measurement system for the MMF is under construction. It is similar to a prototype system we built two years ago in the Sector 10 alignment lab at SLAC. At that time, our goal was to measure the lab temperature to {+-}0.1 C. The system has worked well for two years and has maintained its accuracy. For the MMF system, we propose better sensors and a more extensive calibration program to achieve the factor of 10 increase in accuracy. In this note we describe the measurement system under construction. We motivate our choice of system components and give an overview of the system. Most of the software for the system has been written and will be discussed. We discuss error sources in temperature measurements and show how these errors have been dealt with. The calibration system is described in detail. All the LCLS undulators must be tuned in the Magnetic Measurement Facility at the same temperature to within {+-}0.1 C. In order to ensure this, we are building a system to measure the temperature of the

Action errors, error management, and learning in organizations.

Science.gov (United States)

Frese, Michael; Keith, Nina

2015-01-03

Every organization is confronted with errors. Most errors are corrected easily, but some may lead to negative consequences. Organizations often focus on error prevention as a single strategy for dealing with errors. Our review suggests that error prevention needs to be supplemented by error management--an approach directed at effectively dealing with errors after they have occurred, with the goal of minimizing negative and maximizing positive error consequences (examples of the latter are learning and innovations). After defining errors and related concepts, we review research on error-related processes affected by error management (error detection, damage control). Empirical evidence on positive effects of error management in individuals and organizations is then discussed, along with emotional, motivational, cognitive, and behavioral pathways of these effects. Learning from errors is central, but like other positive consequences, learning occurs under certain circumstances--one being the development of a mind-set of acceptance of human error.

Modeling coherent errors in quantum error correction

Science.gov (United States)

Greenbaum, Daniel; Dutton, Zachary

2018-01-01

Analysis of quantum error correcting codes is typically done using a stochastic, Pauli channel error model for describing the noise on physical qubits. However, it was recently found that coherent errors (systematic rotations) on physical data qubits result in both physical and logical error rates that differ significantly from those predicted by a Pauli model. Here we examine the accuracy of the Pauli approximation for noise containing coherent errors (characterized by a rotation angle ɛ) under the repetition code. We derive an analytic expression for the logical error channel as a function of arbitrary code distance d and concatenation level n, in the small error limit. We find that coherent physical errors result in logical errors that are partially coherent and therefore non-Pauli. However, the coherent part of the logical error is negligible at fewer than {ε }-({dn-1)} error correction cycles when the decoder is optimized for independent Pauli errors, thus providing a regime of validity for the Pauli approximation. Above this number of correction cycles, the persistent coherent logical error will cause logical failure more quickly than the Pauli model would predict, and this may need to be combated with coherent suppression methods at the physical level or larger codes.

Errors in causal inference: an organizational schema for systematic error and random error.

Science.gov (United States)

Suzuki, Etsuji; Tsuda, Toshihide; Mitsuhashi, Toshiharu; Mansournia, Mohammad Ali; Yamamoto, Eiji

2016-11-01

To provide an organizational schema for systematic error and random error in estimating causal measures, aimed at clarifying the concept of errors from the perspective of causal inference. We propose to divide systematic error into structural error and analytic error. With regard to random error, our schema shows its four major sources: nondeterministic counterfactuals, sampling variability, a mechanism that generates exposure events and measurement variability. Structural error is defined from the perspective of counterfactual reasoning and divided into nonexchangeability bias (which comprises confounding bias and selection bias) and measurement bias. Directed acyclic graphs are useful to illustrate this kind of error. Nonexchangeability bias implies a lack of "exchangeability" between the selected exposed and unexposed groups. A lack of exchangeability is not a primary concern of measurement bias, justifying its separation from confounding bias and selection bias. Many forms of analytic errors result from the small-sample properties of the estimator used and vanish asymptotically. Analytic error also results from wrong (misspecified) statistical models and inappropriate statistical methods. Our organizational schema is helpful for understanding the relationship between systematic error and random error from a previously less investigated aspect, enabling us to better understand the relationship between accuracy, validity, and precision. Copyright © 2016 Elsevier Inc. All rights reserved.

Reversible beam heater for suppression of microbunching instability by transverse gradient undulators

Science.gov (United States)

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.

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

Science.gov (United States)

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.

First experimental results from IBM/TENN/TULANE/LLNL/LBL undulator beamline at the advanced light source

International Nuclear Information System (INIS)

Jia, J.J.; Callcott, T.A.; Yurkas, J.; Ellis, A.W.; Himpsel, F.J.; Samant, M.G.; Stoehr, J.; Ederer, D.L.; Carlisle, J.A.; Hudson, E.A.; Terminello, L.J.; Shuh, D.K.; Perera, R.C.C.

1995-01-01

The IBM/TENN/TULANE/LLNL/LBL Beamline 8.0 at the advanced light source combining a 5.0 cm, 89 period undulator with a high-throughput, high-resolution spherical grating monochromator, provides a powerful excitation source over a spectral range of 70--1200 eV for surface physics and material science research. The beamline progress and the first experimental results obtained with a fluorescence end station on graphite and titanium oxides are presented here. The dispersive features in K emission spectra of graphite excited near threshold, and found a clear relationship between them and graphite band structure are observed. The monochromator is operated at a resolving power of roughly 2000, while the spectrometer has a resolving power of 400 for these fluorescence experiments

Error begat error: design error analysis and prevention in social infrastructure projects.

Science.gov (United States)

Love, Peter E D; Lopez, Robert; Edwards, David J; Goh, Yang M

2012-09-01

Design errors contribute significantly to cost and schedule growth in social infrastructure projects and to engineering failures, which can result in accidents and loss of life. Despite considerable research that has addressed their error causation in construction projects they still remain prevalent. This paper identifies the underlying conditions that contribute to design errors in social infrastructure projects (e.g. hospitals, education, law and order type buildings). A systemic model of error causation is propagated and subsequently used to develop a learning framework for design error prevention. The research suggests that a multitude of strategies should be adopted in congruence to prevent design errors from occurring and so ensure that safety and project performance are ameliorated. Copyright © 2011. Published by Elsevier Ltd.

Modular filter design for the white-beam undulator/wiggler beamlines at the Advanced Photon Source

International Nuclear Information System (INIS)

Brite, C.; Shu, D.; Nian, T.; Wang, Z.; Haeffner, D.; Alp, E.; Kuzay, T.

1994-01-01

A new filter has been designed at Argonne National Laboratory that is intended for the use in undulator/wiggler beamlines at the Advanced Photon Source. The water-cooled frame allows up to four individual filter foil banks simultaneously in the beam path. Additionally, the bottom of each frame holds two thin (20 μm) uncooled carbon filters in tandem for low-energy filtering. Therefore, a maximum of 625 filter selection combinations is theoretically possible. The design is intelligent, compact and modular, with great flexibility for the users. To prevent accidental movement of the filter, effort has been taken to provide a mechanically locked, fail-safe actuator system. Programming aspects are under development as part of our general personnel and equipment protection system. Aspects of the design and operational principles of the filter are presented in this paper

Assessment of the most recent satellite based digital elevation models of Egypt

Science.gov (United States)

Rabah, Mostafa; El-Hattab, Ahmed; Abdallah, Mohamed

2017-12-01

Digital Elevation Model (DEM) is crucial to a wide range of surveying and civil engineering applications worldwide. Some of the DEMs such as ASTER, SRTM1 and SRTM3 are freely available open source products. In order to evaluate the three DEMs, the contribution of EGM96 are removed and all DEMs heights are becoming ellipsoidal height. This step was done to avoid the errors occurred due to EGM96. 601 points of observed ellipsoidal heights compared with the three DEMs, the results show that the SRTM1 is the most accurate one, that produces mean height difference and standard deviations equal 2.89 and ±8.65 m respectively. In order to increase the accuracy of SRTM1 in EGYPT, a precise Global Geopotential Model (GGM) is needed to convert the SRTM1 ellipsoidal height to orthometric height, so that, we quantify the precision of most-recent released GGM (five models). The results show that, the GECO model is the best fit global models over Egypt, which produces a standard deviation of geoid undulation differences equals ±0.42 m over observed 17 HARN GPS/leveling stations. To confirm an enhanced DEM in EGYPT, the two orthometric height models (SRTM1 ellipsoidal height + EGM96) and (SRTM1 ellipsoidal height + GECO) are assessment with 17 GPS/leveling stations and 112 orthometric height stations, the results show that the estimated height differences between the SRTM1 before improvements and the enhanced model are at rate of 0.44 m and 0.06 m respectively.

Errors, error detection, error correction and hippocampal-region damage: data and theories.

Science.gov (United States)

MacKay, Donald G; Johnson, Laura W

2013-11-01

This review and perspective article outlines 15 observational constraints on theories of errors, error detection, and error correction, and their relation to hippocampal-region (HR) damage. The core observations come from 10 studies with H.M., an amnesic with cerebellar and HR damage but virtually no neocortical damage. Three studies examined the detection of errors planted in visual scenes (e.g., a bird flying in a fish bowl in a school classroom) and sentences (e.g., I helped themselves to the birthday cake). In all three experiments, H.M. detected reliably fewer errors than carefully matched memory-normal controls. Other studies examined the detection and correction of self-produced errors, with controls for comprehension of the instructions, impaired visual acuity, temporal factors, motoric slowing, forgetting, excessive memory load, lack of motivation, and deficits in visual scanning or attention. In these studies, H.M. corrected reliably fewer errors than memory-normal and cerebellar controls, and his uncorrected errors in speech, object naming, and reading aloud exhibited two consistent features: omission and anomaly. For example, in sentence production tasks, H.M. omitted one or more words in uncorrected encoding errors that rendered his sentences anomalous (incoherent, incomplete, or ungrammatical) reliably more often than controls. Besides explaining these core findings, the theoretical principles discussed here explain H.M.'s retrograde amnesia for once familiar episodic and semantic information; his anterograde amnesia for novel information; his deficits in visual cognition, sentence comprehension, sentence production, sentence reading, and object naming; and effects of aging on his ability to read isolated low frequency words aloud. These theoretical principles also explain a wide range of other data on error detection and correction and generate new predictions for future test. Copyright © 2013 Elsevier Ltd. All rights reserved.

Scheme for generation of fully-coherent, TW power level hard X-ray pulses from baseline undulators at the European X-ray FEL

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2010-07-01

The most promising way to increase the output power of an X-ray FEL (XFEL) is by tapering the magnetic field of the undulator. Also, significant increase in power is achievable by starting the FEL process from a monochromatic seed rather than from noise. This report proposes to make use of a cascade self-seeding scheme with wake monochromators in a tunable-gap baseline undulator at the European XFEL to create a source capable of delivering coherent radiation of unprecedented characteristics at hard X-ray wavelengths. Compared with SASE X-ray FEL parameters, the radiation from the new source has three truly unique aspects: complete longitudinal and transverse coherence, and a peak brightness three orders of magnitude higher than what is presently available at LCLS. Additionally, the new source will generate hard X-ray beam at extraordinary peak (TW) and average (kW) power level. The proposed source can thus revolutionize fields like single biomolecule imaging, inelastic scattering and nuclear resonant scattering. The self-seeding scheme with the wake monochromator is extremely compact, and takes almost no cost and time to be implemented. The upgrade proposed in this paper could take place during the commissioning stage of the European XFEL, opening a vast new range of applications from the very beginning of operations.We present feasibility study and examplifications for the SASE2 line of the European XFEL. (orig.)

Elasticity-based patterning of red blood cells on undulated lipid membranes supported on porous topographic substrates.

Science.gov (United States)

Lee, Sang-Wook; Jeong, Cherlhyun; Lee, Sin-Doo

2009-03-26

We describe elasticity-based patterning of human red blood cells (RBCs) into a microarray form on supported lipid membranes (SLMs) prepared on a solid substrate having two types of topographic patterns, porous and flat regions. The underlying concept is to precisely control the interplay between adhesion and the bending rigidity of the RBCs that interact with the SLMs. Attachment of the RBCs on highly undulated SLMs formed on the porous region is not energetically favorable, since membrane bending of the RBCs costs a high curvature elastic energy which exceeds adhesion. The RBCs are thus selectively confined within relatively flat regions of the SLMs without causing considerable elastic distortions. It was found that the population of the RBCs in a single corral is linearly proportional to the area of one element in our microarray.

Dynamical behaviour of FEL devices operating with two undulators having opposite circular polarizations

Energy Technology Data Exchange (ETDEWEB)

Dattoli, G. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Rome (Italy); Ottaviani, P.L. [ENEA, Divisione Fisica Applicata, Centro Ricerche, Bologna (Italy); Bucci, L. [ENEA, Guest Rome (Italy)

2000-07-01

Optical-Klystron FELs operating with undulators having opposite circular polarizations are characterized by a spontaneous emission spectrum which does not exhibit the characteristic interference pattern. The use of the Madey theorem may allow the conclusion that, for such configuration, the dispersive section does not provide any gain enhancement. In this paper it has been analyzed the problem from a dynamical point of view and clarify how the optical field evolve, what is the role of the bunching and how the consequences of the Madey theorem should be correctly understood. [Italian] Klystron ottici operanti con ondulatori aventi polarizzazione elicoidali opposte, sono caratterizzati da uno spettro di emissione spontanea senza il termine interferenziale dovuto alla sezione dispersiva. L'uso del teorema di Madey indurrebbe alla conclusione che, per una tale configurazione, la sezione dispersiva non induce nessun aumento del guadagno. In questo lavoro analizziamo il problema da un punto di vista dinamico che chiarisce l'evoluzione del campo ottico, quale e' il ruolo del bunching e come le conseguenze del teorema di Madey debbano essere interpretate.

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

Energy Technology Data Exchange (ETDEWEB)

Moog, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Dejus, R. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Sasaki, S. [Argonne National Lab. (ANL), Argonne, IL (United States)

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-type 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.

Learning time-dependent noise to reduce logical errors: real time error rate estimation in quantum error correction

Science.gov (United States)

Huo, Ming-Xia; Li, Ying

2017-12-01

Quantum error correction is important to quantum information processing, which allows us to reliably process information encoded in quantum error correction codes. Efficient quantum error correction benefits from the knowledge of error rates. We propose a protocol for monitoring error rates in real time without interrupting the quantum error correction. Any adaptation of the quantum error correction code or its implementation circuit is not required. The protocol can be directly applied to the most advanced quantum error correction techniques, e.g. surface code. A Gaussian processes algorithm is used to estimate and predict error rates based on error correction data in the past. We find that using these estimated error rates, the probability of error correction failures can be significantly reduced by a factor increasing with the code distance.

Precision white-beam slit design for high power density x-ray undulator beamlines at the Advanced Photon Source

International Nuclear Information System (INIS)

Shu, D.; Brite, C.; Nian, T.

1994-01-01

A set of precision horizontal and vertical white-beam slits has been designed for the Advanced Photon Source (APS) X-ray undulator beamlines at Argonne National Laboratory. There are several new design concepts applied in this slit set, including: grazing-incidence knife-edge configuration to minimize the scattering of X-rays downstream, enhanced heat transfer tubing to provide water cooling, and a second slit to eliminate the thermal distortion on the slit knife edge. The novel aspect of this design is the use of two L-shaped knife-edge assemblies, which are manipulated by two precision X-Z stepping linear actuators. The principal and structural details of the design for this slit set are presented in this paper

Medication errors: prescribing faults and prescription errors.

Science.gov (United States)

Velo, Giampaolo P; Minuz, Pietro

2009-06-01

1. Medication errors are common in general practice and in hospitals. Both errors in the act of writing (prescription errors) and prescribing faults due to erroneous medical decisions can result in harm to patients. 2. Any step in the prescribing process can generate errors. Slips, lapses, or mistakes are sources of errors, as in unintended omissions in the transcription of drugs. Faults in dose selection, omitted transcription, and poor handwriting are common. 3. Inadequate knowledge or competence and incomplete information about clinical characteristics and previous treatment of individual patients can result in prescribing faults, including the use of potentially inappropriate medications. 4. An unsafe working environment, complex or undefined procedures, and inadequate communication among health-care personnel, particularly between doctors and nurses, have been identified as important underlying factors that contribute to prescription errors and prescribing faults. 5. Active interventions aimed at reducing prescription errors and prescribing faults are strongly recommended. These should be focused on the education and training of prescribers and the use of on-line aids. The complexity of the prescribing procedure should be reduced by introducing automated systems or uniform prescribing charts, in order to avoid transcription and omission errors. Feedback control systems and immediate review of prescriptions, which can be performed with the assistance of a hospital pharmacist, are also helpful. Audits should be performed periodically.

Thermal undulations of quasi-spherical vesicles stabilized by gravity

DEFF Research Database (Denmark)

Henriksen, Jonas Rosager; Ipsen, John Hjorth

2002-01-01

) = DeltapgR(4)/k. The contributions from gravity are in most experimental situations small and thus negligible, but for values of go above a certain limit, the perturbational corrections must be included. Expressions for the relative error on the flicker spectrum have been worked out, so that it is possible...... to define the regime where gravity is negligible. An upper limit of go has also been identified, where the error in all modes of the flicker spectrum is significant due to distortion of the mean shape....

Proposal to generate 10 TW level femtosecond X-ray pulses from a baseline undulator in conventional SASE regime at the European XFEL

Energy Technology Data Exchange (ETDEWEB)

Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany)

2013-08-15

Output characteristics of the European XFEL have been previously studied assuming an operation point at 5 kA peak current. In this paper we explore the possibility to go well beyond such nominal peak current level. In order to illustrate the potential of the European XFEL accelerator complex we consider a bunch with 0.25 nC charge, compressed up to a peak current of 45 kA. An advantage of operating at such high peak current is the increase of the X-ray output peak power without any modification to the baseline design. Based on start-to-end simulations, we demonstrate that such high peak current, combined with undulator tapering, allows one to achieve up to a 100-fold increase in a peak power in the conventional SASE regime, compared to the nominal mode of operation. In particular, we find that 10 TW-power level, femtosecond x-ray pulses can be generated in the photon energy range between 3 keV and 5 keV, which is optimal for single biomolecule imaging. Our simulations are based on the exploitation of all the 21 cells foreseen for the SASE3 undulator beamline, and indicate that one can achieve diffraction to the desired resolution with 15 mJ (corresponding to about 3.10{sup 13} photons) in pulses of about 3 fs, in the case of a 100 nm focus at the photon energy of 3.5 keV.

Proposal to generate 10 TW level femtosecond X-ray pulses from a baseline undulator in conventional SASE regime at the European XFEL

International Nuclear Information System (INIS)

Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor; Geloni, Gianluca

2013-08-01

Output characteristics of the European XFEL have been previously studied assuming an operation point at 5 kA peak current. In this paper we explore the possibility to go well beyond such nominal peak current level. In order to illustrate the potential of the European XFEL accelerator complex we consider a bunch with 0.25 nC charge, compressed up to a peak current of 45 kA. An advantage of operating at such high peak current is the increase of the X-ray output peak power without any modification to the baseline design. Based on start-to-end simulations, we demonstrate that such high peak current, combined with undulator tapering, allows one to achieve up to a 100-fold increase in a peak power in the conventional SASE regime, compared to the nominal mode of operation. In particular, we find that 10 TW-power level, femtosecond x-ray pulses can be generated in the photon energy range between 3 keV and 5 keV, which is optimal for single biomolecule imaging. Our simulations are based on the exploitation of all the 21 cells foreseen for the SASE3 undulator beamline, and indicate that one can achieve diffraction to the desired resolution with 15 mJ (corresponding to about 3.10 13 photons) in pulses of about 3 fs, in the case of a 100 nm focus at the photon energy of 3.5 keV.

Opportunities for two-color experiments at the SASE3 undulator line of the European XFEL

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca; Mazza, Tommaso; Meyer, Michael; Serkez, Svitozar [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2017-06-15

X-ray Free Electron Lasers (XFELs) have been proven to generate short and powerful radiation pulses allowing for a wide class of novel experiments. If an XFEL facility supports the generation of two X-ray pulses with different wavelengths and controllable delay, the range of possible experiments is broadened even further to include X-ray-pump/X-ray-probe applications. In this work we discuss the possibility of applying a simple and cost-effective method for producing two-color pulses at the SASE3 soft X-ray beamline of the European XFEL. The technique is based on the installation of a magnetic chicane in the baseline undulator and can be accomplished in several steps. We discuss the scientific interest of this upgrade for the Small Quantum Systems (SQS) instrument, in connection with the high-repetition rate of the European XFEL, and we provide start-to-end simulations up to the radiation focus on the sample, proving the feasibility of our concept.

Focusing of undulator light at SPEAR with a lacquer-coated mirror to power densities of 10/sup 9/ watts/cm/sup 2/

International Nuclear Information System (INIS)

Tatchyn, R.; Csonka, P.; Kilic, H.; Watanabe, H.; Fuller, A.; Beck, M.; Toor, A.; Underwood, J.; Catura, R.

1987-01-01

A lacquer-coated, diamond turned Cu ellipsoid has been used to micro-focus undulator light from Beam Line V at SPEAR down to a half-power diameter of about 13 microns. This spot was source-size limited, as has been demonstrated with ray tracings of the optical system. The symmetry of the image, as well as its size and power density, clearly make this optic ideal for many soft x-ray applications, in particular for x-ray microscopy, microprobes, and for pumping soft x-ray transitions in various media

Challenge and Error: Critical Events and Attention-Related Errors

Science.gov (United States)

Cheyne, James Allan; Carriere, Jonathan S. A.; Solman, Grayden J. F.; Smilek, Daniel

2011-01-01

Attention lapses resulting from reactivity to task challenges and their consequences constitute a pervasive factor affecting everyday performance errors and accidents. A bidirectional model of attention lapses (error [image omitted] attention-lapse: Cheyne, Solman, Carriere, & Smilek, 2009) argues that errors beget errors by generating attention…

Error forecasting schemes of error correction at receiver

International Nuclear Information System (INIS)

Bhunia, C.T.

2007-08-01

To combat error in computer communication networks, ARQ (Automatic Repeat Request) techniques are used. Recently Chakraborty has proposed a simple technique called the packet combining scheme in which error is corrected at the receiver from the erroneous copies. Packet Combining (PC) scheme fails: (i) when bit error locations in erroneous copies are the same and (ii) when multiple bit errors occur. Both these have been addressed recently by two schemes known as Packet Reversed Packet Combining (PRPC) Scheme, and Modified Packet Combining (MPC) Scheme respectively. In the letter, two error forecasting correction schemes are reported, which in combination with PRPC offer higher throughput. (author)

Operator errors

International Nuclear Information System (INIS)

Knuefer; Lindauer

1980-01-01

Besides that at spectacular events a combination of component failure and human error is often found. Especially the Rasmussen-Report and the German Risk Assessment Study show for pressurised water reactors that human error must not be underestimated. Although operator errors as a form of human error can never be eliminated entirely, they can be minimized and their effects kept within acceptable limits if a thorough training of personnel is combined with an adequate design of the plant against accidents. Contrary to the investigation of engineering errors, the investigation of human errors has so far been carried out with relatively small budgets. Intensified investigations in this field appear to be a worthwhile effort. (orig.)

How Do Simulated Error Experiences Impact Attitudes Related to Error Prevention?

Science.gov (United States)

Breitkreuz, Karen R; Dougal, Renae L; Wright, Melanie C

2016-10-01

The objective of this project was to determine whether simulated exposure to error situations changes attitudes in a way that may have a positive impact on error prevention behaviors. Using a stratified quasi-randomized experiment design, we compared risk perception attitudes of a control group of nursing students who received standard error education (reviewed medication error content and watched movies about error experiences) to an experimental group of students who reviewed medication error content and participated in simulated error experiences. Dependent measures included perceived memorability of the educational experience, perceived frequency of errors, and perceived caution with respect to preventing errors. Experienced nursing students perceived the simulated error experiences to be more memorable than movies. Less experienced students perceived both simulated error experiences and movies to be highly memorable. After the intervention, compared with movie participants, simulation participants believed errors occurred more frequently. Both types of education increased the participants' intentions to be more cautious and reported caution remained higher than baseline for medication errors 6 months after the intervention. This study provides limited evidence of an advantage of simulation over watching movies describing actual errors with respect to manipulating attitudes related to error prevention. Both interventions resulted in long-term impacts on perceived caution in medication administration. Simulated error experiences made participants more aware of how easily errors can occur, and the movie education made participants more aware of the devastating consequences of errors.

Statistical errors in Monte Carlo estimates of systematic errors

Energy Technology Data Exchange (ETDEWEB)

Roe, Byron P. [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States)]. E-mail: byronroe@umich.edu

2007-01-01

For estimating the effects of a number of systematic errors on a data sample, one can generate Monte Carlo (MC) runs with systematic parameters varied and examine the change in the desired observed result. Two methods are often used. In the unisim method, the systematic parameters are varied one at a time by one standard deviation, each parameter corresponding to a MC run. In the multisim method (see ), each MC run has all of the parameters varied; the amount of variation is chosen from the expected distribution of each systematic parameter, usually assumed to be a normal distribution. The variance of the overall systematic error determination is derived for each of the two methods and comparisons are made between them. If one focuses not on the error in the prediction of an individual systematic error, but on the overall error due to all systematic errors in the error matrix element in data bin m, the number of events needed is strongly reduced because of the averaging effect over all of the errors. For simple models presented here the multisim model was far better if the statistical error in the MC samples was larger than an individual systematic error, while for the reverse case, the unisim model was better. Exact formulas and formulas for the simple toy models are presented so that realistic calculations can be made. The calculations in the present note are valid if the errors are in a linear region. If that region extends sufficiently far, one can have the unisims or multisims correspond to k standard deviations instead of one. This reduces the number of events required by a factor of k{sup 2}.

Statistical errors in Monte Carlo estimates of systematic errors

International Nuclear Information System (INIS)

Roe, Byron P.

2007-01-01

For estimating the effects of a number of systematic errors on a data sample, one can generate Monte Carlo (MC) runs with systematic parameters varied and examine the change in the desired observed result. Two methods are often used. In the unisim method, the systematic parameters are varied one at a time by one standard deviation, each parameter corresponding to a MC run. In the multisim method (see ), each MC run has all of the parameters varied; the amount of variation is chosen from the expected distribution of each systematic parameter, usually assumed to be a normal distribution. The variance of the overall systematic error determination is derived for each of the two methods and comparisons are made between them. If one focuses not on the error in the prediction of an individual systematic error, but on the overall error due to all systematic errors in the error matrix element in data bin m, the number of events needed is strongly reduced because of the averaging effect over all of the errors. For simple models presented here the multisim model was far better if the statistical error in the MC samples was larger than an individual systematic error, while for the reverse case, the unisim model was better. Exact formulas and formulas for the simple toy models are presented so that realistic calculations can be made. The calculations in the present note are valid if the errors are in a linear region. If that region extends sufficiently far, one can have the unisims or multisims correspond to k standard deviations instead of one. This reduces the number of events required by a factor of k 2

Field error lottery

Energy Technology Data Exchange (ETDEWEB)

Elliott, C.J.; McVey, B. (Los Alamos National Lab., NM (USA)); Quimby, D.C. (Spectra Technology, Inc., Bellevue, WA (USA))

1990-01-01

The level of field errors in an FEL is an important determinant of its performance. We have computed 3D performance of a large laser subsystem subjected to field errors of various types. These calculations have been guided by simple models such as SWOOP. The technique of choice is utilization of the FELEX free electron laser code that now possesses extensive engineering capabilities. Modeling includes the ability to establish tolerances of various types: fast and slow scale field bowing, field error level, beam position monitor error level, gap errors, defocusing errors, energy slew, displacement and pointing errors. Many effects of these errors on relative gain and relative power extraction are displayed and are the essential elements of determining an error budget. The random errors also depend on the particular random number seed used in the calculation. The simultaneous display of the performance versus error level of cases with multiple seeds illustrates the variations attributable to stochasticity of this model. All these errors are evaluated numerically for comprehensive engineering of the system. In particular, gap errors are found to place requirements beyond mechanical tolerances of {plus minus}25{mu}m, and amelioration of these may occur by a procedure utilizing direct measurement of the magnetic fields at assembly time. 4 refs., 12 figs.

A Study on Earthquake-Related Geoid Deformation at Beijing-Tangshan and West Yunnan During 1985-1998

Science.gov (United States)

Li, Z.

2006-05-01

Based on the determination of the non-tidal variations in the deflection of the vertical (or PlumbLine Variations, PLVs) at Beijing astronomical observatory, the work has been extended into a determination of the PLV array within a 4 x 1 (degree) area at Beijing-Tangshan. By repeated observations of the gravimetric network, 46 batches of this PLV array, and consequently the relative geoid deformation (RGD), of the area during 1987- 1998 have been determined. Together with the 23 earthquakes (Mb > 4.0) in the area during the same period, a comparison is done between an earthquake event and the related RGD. Similar study has also been carried out for the case in West Yunnan, where 32 batches of repeated gravimetric observations of the network there during 1985-1998 have been performed from which the 32 PLV array, as well as the corresponding RGD, of a 2 x 2 (dergee) area has been calculated. A comparison is also done at West Yunnan between an earthquake event and its related RGD. It is interesting to see that the earthquake and the RGD measured are related. It appears that there is usually a detectable RGD nearby well before an earthquake, but a contrary RGD afterwards. The study provides us a new approach in geodesy on the RGD determination, as well as a new measurable phenomenon in an earthquake event at Beijing-Tangshan and West Yunnan. The study also provides us evidence in which the existence of the PLVs, as well as the corresponding RGD, at Beijing- Tangshan and West Yunnan becomes more conclusive. Their potential usage in geodesy and seismology, as well as in other related sciences, is now expected.

Errors in clinical laboratories or errors in laboratory medicine?

Science.gov (United States)

Plebani, Mario

2006-01-01

Laboratory testing is a highly complex process and, although laboratory services are relatively safe, they are not as safe as they could or should be. Clinical laboratories have long focused their attention on quality control methods and quality assessment programs dealing with analytical aspects of testing. However, a growing body of evidence accumulated in recent decades demonstrates that quality in clinical laboratories cannot be assured by merely focusing on purely analytical aspects. The more recent surveys on errors in laboratory medicine conclude that in the delivery of laboratory testing, mistakes occur more frequently before (pre-analytical) and after (post-analytical) the test has been performed. Most errors are due to pre-analytical factors (46-68.2% of total errors), while a high error rate (18.5-47% of total errors) has also been found in the post-analytical phase. Errors due to analytical problems have been significantly reduced over time, but there is evidence that, particularly for immunoassays, interference may have a serious impact on patients. A description of the most frequent and risky pre-, intra- and post-analytical errors and advice on practical steps for measuring and reducing the risk of errors is therefore given in the present paper. Many mistakes in the Total Testing Process are called "laboratory errors", although these may be due to poor communication, action taken by others involved in the testing process (e.g., physicians, nurses and phlebotomists), or poorly designed processes, all of which are beyond the laboratory's control. Likewise, there is evidence that laboratory information is only partially utilized. A recent document from the International Organization for Standardization (ISO) recommends a new, broader definition of the term "laboratory error" and a classification of errors according to different criteria. In a modern approach to total quality, centered on patients' needs and satisfaction, the risk of errors and mistakes

ERF/ERFC, Calculation of Error Function, Complementary Error Function, Probability Integrals

International Nuclear Information System (INIS)

Vogel, J.E.

1983-01-01

1 - Description of problem or function: ERF and ERFC are used to compute values of the error function and complementary error function for any real number. They may be used to compute other related functions such as the normal probability integrals. 4. Method of solution: The error function and complementary error function are approximated by rational functions. Three such rational approximations are used depending on whether - x .GE.4.0. In the first region the error function is computed directly and the complementary error function is computed via the identity erfc(x)=1.0-erf(x). In the other two regions the complementary error function is computed directly and the error function is computed from the identity erf(x)=1.0-erfc(x). The error function and complementary error function are real-valued functions of any real argument. The range of the error function is (-1,1). The range of the complementary error function is (0,2). 5. Restrictions on the complexity of the problem: The user is cautioned against using ERF to compute the complementary error function by using the identity erfc(x)=1.0-erf(x). This subtraction may cause partial or total loss of significance for certain values of x

Hydraulic Transients Caused by Air Expulsion During Rapid Filling of Undulating Pipelines

Directory of Open Access Journals (Sweden)

Ciro Apollonio

2016-01-01

Full Text Available One of the main issues arising during the rapid filling of a pipeline is the pressure transient which originates after the entrapped air has been expelled at the air release valve. Because of the difference in density between water and air, a pressure transient originates at the impact of the water column. Many authors have analyzed the problem, both from the theoretical and the experimental standpoint. Nevertheless, mainly vertical or horizontal pipelines have been analyzed, whereas in real field applications, the pipe profile is a sequence of ascending and descending pipes, with air release/vacuum valves at high points. To overcome lack of knowledge regarding this latter case, laboratory experiments were carried out to simulate the filling of an undulating pipeline, initially empty at atmospheric pressure. The pipe profile has a high point where an orifice is installed for air venting, so as to simulate the air release valve at intermediate high point of a supply pipeline. In the experiments, the diameter of the orifice and the opening degree of both upstream and downstream valves were varied, in order to analyze their effect on the pressure transient. The experiments were also carried out with a longer descending pipe, in order to assess the effects on the pressure surge of the air volume downstream of the orifice.

A methodology for translating positional error into measures of attribute error, and combining the two error sources

Science.gov (United States)

Yohay Carmel; Curtis Flather; Denis Dean

2006-01-01

This paper summarizes our efforts to investigate the nature, behavior, and implications of positional error and attribute error in spatiotemporal datasets. Estimating the combined influence of these errors on map analysis has been hindered by the fact that these two error types are traditionally expressed in different units (distance units, and categorical units,...

Statistical errors in Monte Carlo estimates of systematic errors

Science.gov (United States)

Roe, Byron P.

2007-01-01

For estimating the effects of a number of systematic errors on a data sample, one can generate Monte Carlo (MC) runs with systematic parameters varied and examine the change in the desired observed result. Two methods are often used. In the unisim method, the systematic parameters are varied one at a time by one standard deviation, each parameter corresponding to a MC run. In the multisim method (see ), each MC run has all of the parameters varied; the amount of variation is chosen from the expected distribution of each systematic parameter, usually assumed to be a normal distribution. The variance of the overall systematic error determination is derived for each of the two methods and comparisons are made between them. If one focuses not on the error in the prediction of an individual systematic error, but on the overall error due to all systematic errors in the error matrix element in data bin m, the number of events needed is strongly reduced because of the averaging effect over all of the errors. For simple models presented here the multisim model was far better if the statistical error in the MC samples was larger than an individual systematic error, while for the reverse case, the unisim model was better. Exact formulas and formulas for the simple toy models are presented so that realistic calculations can be made. The calculations in the present note are valid if the errors are in a linear region. If that region extends sufficiently far, one can have the unisims or multisims correspond to k standard deviations instead of one. This reduces the number of events required by a factor of k2. The specific terms unisim and multisim were coined by Peter Meyers and Steve Brice, respectively, for the MiniBooNE experiment. However, the concepts have been developed over time and have been in general use for some time.