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Improving and extending performance at synchrotron radiation facilities

Description: Synchrotron radiation facilities around the world have now matured through three generations. The latest facilities have all met or exceeded their design specifications and are learning how to cope with the ever more demanding requests of the user community, especially concerning beam stability. The older facilities remain competitive by extending the unique features of their design, and by developing novel insertion devices. In this paper we survey the beam characteristics achieved at third-generation sources and explore the improvements made at earlier generation facilities.
Date: May 1, 1997
Creator: Jackson, A.
Partner: UNT Libraries Government Documents Department

Performance of the TLS at SRRC

Description: 3-year operation experiences of the 1.3 GeV synchrotron radiation facility at SRRC are presented. Two insertion devices (W20 and U10p) are installed in the storage ring; more are under construction. Single bunch instabilities were measured and ring impedance calculated. Both transverse and longitudinal coupled bunch instabilities were observed and corresponding feedback system constructed. The transverse feedback system is now routinely operated. A fast global orbit feedback system is in the development stage. Lifetime is about 5 hours at 200 mA; plans to increase lifetime are proposed. At present, the machine can be operated at nominal design energy 1.3 GeV with full energy injection and ramped up to 1.5 GeV at 200 mA.
Date: October 1, 1996
Creator: Liu, Y.C.; Chen, J.R.; Chang, C.H.; Hsu, K.T. & Kuo, C.C
Partner: UNT Libraries Government Documents Department

6 GeV light source project cost estimating procedure

Description: To maintain uniformity in estimating the cost requirements of the various components of the 6 GeV Light Source, the following procedure will be used by all the task groups. The procedure uses a Work Breakdown Structure (VBS) to break down the project into manageable, easy to estimate, components. The project is first broken down into major tasks or categories. Then each major division is continuously subdivided until the desired level of detail is achieved. This can be shown best by using the example of the WBS of the Aladdin Upgrade Project, excerpts of which are included in Appendix A.
Date: October 23, 1985
Partner: UNT Libraries Government Documents Department

Innovations in the design of mechanical components for a beamline -- The SRl`95 Workshop 2 summary

Description: The Synchrotron Radiation Instrumentation 1995 Conference (SRI`95) was hosted by the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Of the many workshops within the conference, the SRI`95 Workshop 2 was ``Innovations in the Design of Mechanical Components of a Beamline``. The workshop was attended well with over 140 registrants. The following topics were discussed. Industry`s perspective on the status and future was provided by Huber Diffrationtechnik, Oxford Instruments, and Kohzu Seiko Ltd. on goniometers/diffractometers, advanced manufacturing technique of high heat load components, such as the APS photon shutter, and the specialties of monochromators provided to the third-generation synchrotrons, respectively. This was followed by a description of the engineering of a dual function monochromator design for water-cooled diamond or cryogenically cooled silicon monochromators by CMC CAT/APS. Another category was the nagging problem of sensitivity of the photon beam position monitors (XBPM) to bending magnet radiation (``BM contamination``) and the undulator magnet gap changes. Problem descriptions and suggested solutions were provided by both the Advanced Light Source (ALS) and the APS. Other innovative ideas were the cooling schemes (enhanced cooling of beamline components using metallic porous meshes including cryo-cooled applications); Glidcop photon shutter design using microchannels at the ALS; and window/filter design, manufacture and operational experiences at CHESS and PETRA/HASYLAB. Additional discussions were held on designing for micromotions and precision in the optical support systems and smart user filter schemes. This is a summary of the presentations at the Workshop. 5 refs., 5 figs.
Date: December 31, 1995
Creator: Kuzay, T.M. & Warwick, T.
Partner: UNT Libraries Government Documents Department

Ring Energy Selection and Extra Long Straight Sections for the Advanced Photon Source

Description: Recommended criteria are given for the performance of Advanced Photon Source (APS), taking into consideration undulator tunability criteria and their relationship to the storage ring energy and undulator gap, length of straight sections.
Date: April 1987
Creator: Brown, G.; Cho, Y.; Hastings, J.; Krinsky, S.; Moncton, D. E.; Shenoy, G. K. et al.
Partner: UNT Libraries Government Documents Department

Insertion Device and Beam Line Plans for the Advanced Photon Source : a Report and Recommendations by the Insertion Device and Beam Line Planning Committee

Description: In the 7-GeV Advanced Photon Source (APS) Conceptual Design Report (CDR), fifteen complete experimental beam lines were specified in order to establish a representative technical and cost base for the components involved. In order to optimize the composition of the insertion devices and the beam line, these funds are considered a ''Trust Fund.'' The present report evaluates the optimization for the distribution of these funds so that the short- and long-term research programs will be most productive, making the facility more attractive from the user's point of view. It is recommended that part of the "Trust Fund" be used for the construction of the insertion devices, the front-end components, and the first-optics, minimizing the cost to potential users of completing a beam line. In addition, the possibility of cost savings resulting from replication and standardization of high multiplicity components (such as IDs, front ends, and first-optics instrumentation) is addressed.
Date: February 1987
Creator: Boyce, R.; Hewitt, R.; Morrison, T. I.; Shenoy, G. K.; Thomlinson, W. & Viccaro, P. J.
Partner: UNT Libraries Government Documents Department

Brilliance and flux reduction in imperfect inclined crystals

Description: The inclined crystal geometry has been suggested as a method of reducing the surface absorbed power density of high-heat-load monochromators for third-generation synchrotron radiation sources. Computer simulations have shown that if the crystals are perfectly aligned and have no strains then the diffraction properties of a pair of inclined crystals are very similar to a pair of conventional flat crystals with only subtle effects differentiating the two configurations. However, if the crystals are strained, these subtle differences in the behavior of inclined crystals can result in large beam divergences causing brilliance and flux losses. This manuscript elaborates on these issues and estimates potential brilliance and flux losses from strained inclined crystals at the APS.
Date: January 1, 1996
Creator: Lee, W.K.; Blasdell, R.C.; Fernandez, P.B.; Macrander, A.T. & Mills, D.M.
Partner: UNT Libraries Government Documents Department

Recent advances in insertion devices

Description: Demand for more and better insertion devices (IDs) at new third-generation synchrotron radiation facilities has led to significant advances in ID technology at different laboratories around the world. In this overview of this progress, focus is on those results that apply to IDs in general rather than one specific ID or laboratory. The advances fall into two general categories: those that reduce the net effect that the ID has on the particle beam, and those that enhance the quality of the emitted light spectrum. The need for these advances, factors that are most important inaachieving them, and the current state of the art are discussed.
Date: December 31, 1995
Creator: Gluskin, E. & Moog, E.R.
Partner: UNT Libraries Government Documents Department

The method of boundary perturbation, and its application to wakefield calculations

Description: The boundary perturbation method, suggested by Zhang and (independently) by Chatard-Moulin, Cooper, and their colleagues, is employed to the wakefield calculations for geometrical discontinuities in accelerators. Results are compared with that obtained from the mesh calculations using TBCI. When the perturbation is small and the geometry is suitable for TBCI, agreement is good. Discrepancies observed in other cases are also discussed.
Date: December 31, 1990
Creator: Chou, W.
Partner: UNT Libraries Government Documents Department

A study of heat transfer for two layered composite inclined plate crotch absorbers

Description: Since a copper plate (Z=29) absorbs most of the photon energy very near the surface, the temperature of the surface becomes very high despite of having a high thermal conductivity. On the other hand, a beryllium plate( Z=4) can diffuse the intense radiation throughout the depth of its plate by allowing photons to penetrate, but has a low thermal conductivity (about half of that of a copper). As an effort to combine both merits of Be and Cu, a Be-Cu composite absorber was developed and has been successfully used in CESR. They analyzed composite the heat transfer problem numerically for the case of a vertically located Be-Cu composite cylinder which results in symmetry with respect to the center of photon beam and allows them to consider only half a domain. In this note, an inclined absorber with two layered metal plates is considered and a full domain solution is sought to study the asymmetric heating due to the inclined photon beam penetration heating. An analytical solution for heat transfer is obtained for a full domain using the Fourier integral transformation and of particular interests are the effects of different thickness ratios of two materials and different inclination angles.
Date: November 1, 1989
Creator: Choi, M.
Partner: UNT Libraries Government Documents Department

Length of beamlines and width of the experimental hall at a 6-GeV synchrotron facility

Description: The width of the experimental hall at a 6-GeV facility is closely related to the length of the beamlines. This note addresses this aspect in some detail. In general, no two beamlines will have identical lengths or the placement of various optical elements. Hence fixing the beamline lengths prior to their assignment to specific experiments is difficult. In spite of this fact, a few general conclusions can be made. 1. At least 25 m of all the beamlines will be behind the shielding wall. Within this length many beamline components can be accommodated. 2. For most beamlines on bending magnets, the first optical element will be at 30 m. For a 3:1 aspect ratio for the optics, the hutch will be at about 40-50 m. This will cover most of the general applications like absorption spectroscopy, diffraction, etc. 3. The undulator beamlines will have to be somewhat longer with the experimental hutch located at about 70-80 m for most investigations. This demands the width of the hall to be about 32 m measured from the beamline to the ring road.
Date: November 10, 1985
Creator: Shenoy, G.K. & Knapp, G.S.
Partner: UNT Libraries Government Documents Department

Coherent synchrotron radiation and stability of a short bunch in a compact storage ring

Description: It should be possible to observe coherent synchrotron radiation at millimeter wavelengths in a compact electron storage ring, provided that the bunch can be made sufficiently short. On the other hand, for a short bunch the radiation reaction is so strong that it could cause a longitudinal instability if the current exceeded some threshold. This might cause bunch lengthening, and cut off or reduce the coherent radiation. Using wake fields from simple models of the vacuum chamber, the authors estimate the threshold current for a proposed upgrade of the Brookhaven small x-ray light source, SXLS-Phase 1.
Date: June 1, 1995
Creator: Warnock, R.L. & Bane, K.
Partner: UNT Libraries Government Documents Department

A photon beam position monitor for SSRL beamline 9

Description: We present here the concept of a simple one dimensional photon beam position monitor for use with high power synchrotron radiation beams. It has micron resolution, reasonable linearity in an inexpensive design. Most important, is its insensitivity to diffusely scattered low energy radiation from components upstream of the monitor.
Date: October 1, 1995
Creator: Cerino, J.A.; Rabedeau, T. & Bowen, W.
Partner: UNT Libraries Government Documents Department

Synchrotron power supply light source note

Description: The ring magnet of the injector synchrotron consists of 68 dipole magnets. These magnets are connected in series and are energized from two feed points 180{degrees} apart by two identical 12-phase power supplies. The current in the magnet will be raised linearly to about 1 kA level, and after a small flat top (1 ms to 10 ms typical to provide sufficient time for the bridge to go to inversion mode) the current will be reduced to the injection level of 60 A. The repetition time for the current waveform is 500 ms. In this paper the theory of operation for the power supply along with its design characteristics will be given.
Date: March 1, 1991
Creator: Fathizadeh, M.
Partner: UNT Libraries Government Documents Department

Experimental results on low alpha electron-storage rings

Description: The authors report on experiments performed in two synchrotron light sources, UVSOR and Super-ACO, where the momentum compaction factor is reduced in order to reduce the bunch length. By controlling the second-order momentum compaction factor, UVSOR and Super-ACO have managed to reduce the first-order momentum compaction factor by 100. At low current the resulting bunch lengths are less than 10 ps, a factor of 10 smaller than normal. Measurements of current dependent bunch lengthening in UVSOR are presented and the cause of the bunch lengthening is determined to be potential-well distortion. The authors also show that by operating with a negative momentum compaction factor, SuperACO has achieved shorter bunch lengthening and higher peak currents than at positive momentum compaction.
Date: September 1, 1995
Creator: Robin, D.; Hama, H. & Nadji, A.
Partner: UNT Libraries Government Documents Department

New schemes in the adjustment of bendable, elliptical mirrors using a long trace profiler

Description: The Long Trace Profiler (LTP), an instrument for measuring the slope profile of long X-ray mirrors, has been used for adjusting bendable mirrors. Often an elliptical profile is desired for the mirror surface, since many synchrotron applications involve imaging a point source to a point image. Several techniques have been used in the past for adjusting the profile measured in height or slope of a bendable mirror. Underwood et al. have used collimated X-rays for achieving desired surface shape for bent glass optics. Non linear curve fitting using the simplex algorithm was later used to determine the best fit ellipse to the surface under test. A more recent method uses a combination of least squares polynomial fitting to the measured slope function in order to enable rapid adjustment to the desired shape. The mirror has mechanical adjustments corresponding to the first and second order terms of the desired slope polynomial, which correspond to defocus and coma, respectively. The higher order terms are realized by shaping the width of the mirror to produce the optimal elliptical surface when bent. The difference between desired and measured surface slope profiles allows us to make methodical adjustments to the bendable mirror based on changes in the signs and magnitudes of the polynomial coefficients. This technique gives rapid convergence to the desired shape of the measured surface, even when we have no information about the bender, other than the desired shape of the optical surface. Nonlinear curve fitting can be used at the end of the process for fine adjustments, and to determine the over all best fit parameters of the surface. This technique could be generalized to other shapes such as toroids.
Date: August 1, 1997
Creator: Rah, S.; Locklin, S.; Irick, S. & Howells, M.R.
Partner: UNT Libraries Government Documents Department

First prototype undulator for the LCLS project - mechanical design and prototype lessons.

Description: The design of a new hybrid-type undulator with a fixed gap of 6 mm, a period of 30 mm, and a length of 3.4 m is presented. The undulator line, consisting of 33 such units, is a critical part of the LCLS project, which is one step toward the design of a fourth-generation synchrotron radiation source. Magnetic tolerance of all 33 undulators, as well as the corresponding mechanical uniformity, is a major challenge. A ridged C-shape design with a titanium housing of 12 inch diameter was chosen to provide easy access to the gap area for magnetic measuring and tuning. Lessons learned while working with this prototype are critical for successful project execution. Assembly and tests results, as well as possible design changes, are presented.
Date: August 13, 2002
Creator: Trakhtenberg, E.; Tcheskidov, V.; Erdmann, M.; Vasserman, I.; Vinokurov, N.; Makarov, O. et al.
Partner: UNT Libraries Government Documents Department

Aberration analysis calculations for synchrotron radiation beamline design

Description: The application of ray deviation calculations based on aberration coefficients for a single optical surface for the design of beamline optical systems is reviewed. A systematic development is presented which allows insight into which aberration may be causing the rays to deviate from perfect focus. A new development allowing analytical calculation of line shape is presented.
Date: September 1, 1997
Creator: McKinney, W.R.; Howells, M. & Padmore, H.A.
Partner: UNT Libraries Government Documents Department

A superconducting bending magnet system for a compact synchrotron light source

Description: High intensity, high energy X-rays for use in protein crystallography, nano-machining and medical applications, such as non invasive coronary angiography, can be produced by a 1.2 to 1.5 GeV electron storage ring compact light source with 6 to 8 tesla superconducting bending magnets. Because the bending magnets are to be superconducting, the storage ring energy can be over factor of two lower than a conventional storage ring that delivers same photon energy. The ring, which has superconducting bending magnets, is smaller in circumference and has the advantage of having fewer particles in the ring for a given x ray source intensity. The proposed storage ring is a separated function accelerator ring with six superconducting bending magnet units. Conventional quadruples and correction elements would be located between the bending magnets. Because the synchrotron radiation is generated in the bend, the superconducting bending magnets must have a warm vacuum chamber for the electron beam. Variations of a superferric magnet design have been studied for this application. This report presents a superferric H magnet design that can produce good quality magnetic field in a region that is 50 mm high by 100 mm wide. This modified superferric H magnet design has saturated iron poles but the magnetic flux is returned from one pole to the other through an unsaturated iron return path. The dipole magnet required for a compact storage ring must be physically short (380 mm long), and the field must fall off rapidly at the ends of the magnet. This report describes a preliminary design for a pair of 6.894 tesia, thirty degree bending magnets in a common vacuum vessel for use in a 1.5 GeV compact storage ring light source.
Date: July 1, 1995
Creator: Green, M.A.; Garren, A.A.; Leung, E.M.; Madura, D.D.; Cline, D.B.; Kolonko, J.J. et al.
Partner: UNT Libraries Government Documents Department

Transition undulator radiation as bright infrared sources

Description: 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 characteristics of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.
Date: December 1, 1994
Creator: Kim, Kwang-Je
Partner: UNT Libraries Government Documents Department

Study of Collective Effects for the PEP Low-Emittance Optics

Description: Experimental studies have been performed on the PEP storage ring run at 7.1 GeV in the low-emittance mode. The motivation for this work is to explore the capability of PEP as a dedicated synchrotron radiation source. The long straight sections and low emittance available at PEP make its use for this purpose very attractive, and would produce a source of very high brightness x-ray beams for the scientific community. During the studies, single-bunch current limitations were measured as a function of RF voltage. Thresholds were in the range of 1-2 mA per bunch, which is lower than expected based upon transverse impedance estimates from the PEP collider optics. An increase in threshold current by about 50% was realized by modifying the optics to reduce the magnitude of the horizontal beta functions in the straight sections and at the RF locations. The reason for the lower than expected thresholds has not been resolved. To permit its effective use as a synchrotron radiation source, a beam current of 50-100 mA is desired, which will require that PEP be run in the multibunch mode. Our goal in this study was to investigate the multibunch operating mode to ascertain that reasonable beam intensities were possible. By utilizing many low intensity (0.1-0.25 mA) bunches, stable and reproducible currents of 15-20 mA were achieved. In an attempt to improve this value, one of the idle RF stations was operated in a tune-splitting mode, with only partial success. By adjusting the tuner positions of the unused RF stations, up to 33 mA was ultimately stored, albeit with some evidence for instability. Possible approaches to improving the multibunch stability are discussed.
Date: July 1, 1988
Creator: Zisman, M.S.; Borland, M.; Galayda, J.; Jackson, A.; Kramer, S. & Winick, H.
Partner: UNT Libraries Government Documents Department

A comparison of the Chasman-Green and triple bend achromat lattices

Description: The basic Chasman-Green or double focusing achromat (DFA) lattice, see Fig. 1, represents the most compact and economical of the structures used in low emittance electron storage rings. The main problem with this structure arises from the requirement to operate at zero (or slightly positive) chromaticity. This demands the use of strong sextupole fields, which drive third order structure resonances. These, in turn, place a restriction on the tune of the lattice, particularly in the radial plane. Unfortunately, the DFA structure, which, when operated in the low emittance mode has a fixed phase advance across the achromat, is not very flexible in this regard. We will show, for example, that it is not possible to design for high-beta insertions while maintaining the desired tune. The triple bend achromat (TBA) structure utilizing combined function magnets, see Fig. 2, first described by Vignola as a candidate for the U.S. 6 GeV synchrotron radiation source, is the logical extension of the DFA lattice. Adding an extra bending magnet within the achromat permits the designer to tailor the phase advance across the achromat and the beta value in the insertion region while maintaining the desired tune shift across the cell. This paper details the difficulties with the DFA structure and shows how they are overcome in the TBA design. The principles are illustrated in two lattices which have been optimized for a 1.5 GeV synchrotron light source.
Date: March 1, 1986
Creator: Jackson, A.
Partner: UNT Libraries Government Documents Department

Beam lifetime investigations at SRRC

Description: The beam lifetime of the 1.3 GeV storage ring TLS (Taiwan Light Source) at SRRC was studied. Contributions of the gas scattering lifetime and Touschek scattering lifetime were measured. Effects of insertion devices, RF energy acceptance, chromaticity setting, transverse emittance coupling strength, bunch length, bunch current, etc. on the beam lifetime were measured. It is observed that this machine is Touschek lifetime dominated provided that the transverse emittance coupling strength is low enough and bunch current is reasonably high. In the multibunch users mode it is required to have a longer lifetime; some possible actions to increase beam lifetime have been proposed or implemented.
Date: October 1, 1996
Creator: Kuo, C.C.; Chang, H.P.; Wang, M.H. & Weng, W.T.
Partner: UNT Libraries Government Documents Department