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Cities are major drivers of energy consumption and greenhouse gas emissions--the sources of anthropocentric climate change, whilst also concentrating people, buildings, and infrastructures and therefore potential risk and impacts of the latter. As a consequence, planning for climate change in urban areas does not only provide the opportunity but should necessitate considering interactions between mitigation and adaptation actions. However, existing research found that only a minority of urban areas consider both mitigation and adaptation in their climate action plans, i.e. 147 Climate Change Action Plans (CCAPs) were identified among a representative sample of 885 European cities. We investigate these 147 CCAPs to understand the degree of integration of adaptation and mitigation and draw implications for the maximization of synergies and co-benefits of such a combined approach. Using the developed scoring framework to evaluate the level of integration of CCAPs, the research finds that most of the plans reveal a ‘moderate’ level of integration. Moderate integration characterizes a plan that identifies sources of emissions and vulnerabilities to climate change, as well as some qualitative consideration of the synergies, but one that lacks a systematic consideration of potential integration opportunities. Furthermore, the analysis reveals that one of the main gaps of the evaluation and implementation of more integrated climate change actions in cities is the insufficient quantitative evaluation of the costs and funding schemes for adaptation and mitigation action implementation.

In this study, we report on the fabrication and characterization of periodic Ni and Ni-silicide nanocontact arrays on (1 1 0)Si substrates. From transmission electron microscopy and selected-area electron diffraction analysis, it is found that the epitaxial NiSi 2 is the first and the only silicide phase formed in the nanoscale Ni contact/(1 1 0)Si sample after annealing at a temperature as low as 300 °C, demonstrating that the nanoscale Ni contact is more favorable for the epitaxial growth of NiSi 2 phase on (1 1 0)Si. The orientation relationship between the epitaxial NiSi 2 nanocontacts and the (1 1 0)Si substrate is identified as [1 1 0]NiSi 2 //[1 1 0]Si and ( 1 ¯ 1 1 ¯ )NiSi 2 //( 1 ¯ 1 1 ¯ )Si. For the samples annealed at higher temperatures, all the epitaxial NiSi 2 nanocontacts formed on (1 1 0)Si are anisotropic in shape and elongated along the crystallographic 1 1 ¯ 0 directions. The observed results can be attributed to the higher surface area to volume ratio of Ni nanocontacts and the faster growth rate along the 〈1 1 0〉 directions than along other directions. The size and periodicity of the nanocontacts can be readily controlled by adjusting the diameter of the colloidal nanosphere template. The self-assembled approach proposed here will provide the capability to fabricate other highly-ordered metal silicide nanocontact arrays and may offer potential applications in constructing silicide-based nanodevices.

To enlarge the interaction structure to a feasible dimension and to decrease the required magnetic field to an available strength, the gyrotron devices at THz frequencies must be designed with a high-order-mode interaction, which is weaker in a beam–wave interaction and more susceptible to mode competition. Using the same interaction structure (a circular waveguide) as in the gyrotron traveling-wave amplifier (gyro-TWT), but replacing the axial magnetic field of the gyro-TWT with a tapered helical magnetic field, we found that the gyrating electrons are able to perform strong interaction with the TE11 mode in the THz region. Through an example case, we explored the behavior of the particles and wave fields as in a beam–wave interaction under a modified scheme of the gyro-TWT with a numerical simulation code. The equations required for the simulation are presented. The simulation result of the example case indicates that, through the TE11 beam–wave interaction under the presented scheme, more than one quarter of the beam energy can be converted to the wave at 612.7 GHz and to heat, dissipated on the waveguide wall, of radius 2.5 cm.

Background Establishing a stand-alone cryogenic test stand is of vital importance to ensure the highly reliable and available operation of superconducting radio-frequency module in a synchrotron light source. Operating a cryogenic test stand relies strongly on a capability to deliver two-phase helium along long cryogenic transfer lines. A newly constructed cryogenic test stand with flexible cryogenic transfer lines of length 220 m at National Synchrotron Radiation Research Center is required to support a superconducting radio-frequency module operated at 126.0 kPa with a 40-W dynamic load for a long-term reliability test over weeks. It is designed based on a simple analytical approach with the introduction of a so-called tolerance factor that serves to estimate the pressure drops in transferring a two-phase helium flow with a substantial transfer cryogenic heat load. Tolerance factor 1.5 is adopted based on safety factor 1.5 commonly applied in cryogenic designs to estimate the total mass flow rate of liquid helium demanded. A maximum 60-W dynamic load is verified with experiment measured with heater power 60 W instead after the cryogenic test stand has been installed. Results Aligning the modeled cryogenic accumulated static heat load with the results measured in situ, actual tolerance factor 1.287 is obtained. The feasibility and validity of our simple analytical approach with actual tolerance factor 1.287 have been scrutinized by using five test cases with varied operating conditions. Calculated results show the discrepancies of the pressure drops between the estimated and measured values for both liquid helium and cold gaseous helium transfer lines have an underestimate 0.11 kPa and an overestimate 0.09 kPa, respectively. A discrepancy is foreseen, but remains acceptable for engineering applications from a practical point of view. Conclusions The simple analytical approach with the introduction of a tolerance factor can provide not only insight into optimizing the choice of each lossy cryogenic piping element of the transfer lines in the design phase but also firm guidance for upgrading the present cryogenic transfer lines for its subsequent application.

Solid-state for high power RF application is an attracting and interesting technology which is now become popular in accelerator field. To adopt and master such technique, a 500MHz, 80kW solid-state amplifier is thus developed in NSRRC. The amplifier is consisted of 100 900W amplifier modules which are driving by identical modules. Each module contains input and output directional couplers and status monitoring circuits. To have longer life time and better performance, the RF power transistors are integrated with water cooled heat sink directly. In such a way, the transistors have higher output power and better efficiency. The RF power of each module is combined through coaxial combiner while its DC power is provided by parallel connected DC power supplies which can provide better redundancy and reliability. The home-made solid-state amplifier is demonstrated to have quite high quality RF power and reliability with acceptable power combination efficiency.

An industrially manufactured CESR-type SRF module has been routinely operated at the Taiwan Light Source (TLS) at the National Synchrotron Radiation Research Center (NSRRC) since the beginning of March 2005. The original goals of doubling the electron beam current to increase the synchrotron light intensity and of eliminating the instability caused by the interaction of the electron beams with the cavity’s higher-order modes have been successfully demonstrated. The greatest challenge to the operational reliability, the short mean time between failures, has been successfully overcome. This work reports the operational experience and status of the SRF module at TLS, toward a maximum beam current of 400 mA in decay mode, of 300 mA in top-up mode and of 200 mA in routine operation, over last six months.

1) The storage ring operation energy was raised to 1.5 GeV, the maximum value limited by dipole magnets, to improve electron beam lifetime and to extend its spectrum to higher energies in 1996. 2) Five permanent-magnet insertion devices have been constructed and installed, as listed in Table I, by the end of 1999 to provide synchrotron radiation with higher brightness and energies. In 2003, the U10 undulator was removed and loaned to ANKA, Germany. 3) The booster energy was increased from 1.3 to 1.5 GeV. With this accomplishment, the facility can perform full energy injection and reduces the transient behavior between shifts, opening the possibility of top-up injection mode. 4) The stability of electron beam has been improved. With the raise of electron beam position monitors (EBPM) resolution to better than 1μm, the reduction of both air and cooling water temperature fluctuations to less than ±0.1 , and the °C implementation of the global feedback system, the beam orbit stability of ~ 1μm with a drift of ~ 5μm in a single shift is routinely achievable now.

This paper presents a novel empirical formula for evaluating the axial magnetic attenuation of a circularly cylindrical shield with partial openings at both ends, which is derived under the assumption of scaling law with help of the 3-D magnetostatic code TOSCA for computing the magnetic attenuation of some canonical models. Our formula allows a quick evaluation of the magnetic shielding for design application to a superconducting radio-frequency cavity with less than 10% discrepancy in comparison with that obtained from pure numerical simulations.

A transverse-torsional coupling dynamic model of a planetary gear transmission (PGT) is developed in this paper. In order to ensure the accuracy of the analysis, the mean mesh stiffness and support stiffness are also considered. The stiffness and mass matrices of the gearbox structures are transformed into the joint nodes of bearing or gear supports by substructure method. By solving the eigenvalue of differential equations of motion, the natural frequencies and mode shapes are calculated for uncoupled PGT and coupled model. The influences of mesh stiffness and mass properties on system are discussed by comparing strain and kinetic energy.

In this work, we construct and measure a prototype symmetric Hybrid Adjustable Phase Undulator (HAPU) with nine poles to compare phase change and gap change in terms of their features and performances. HAPU can also provide the different characteristics between the pure and hybrid adjustable phase undulator. The HAPU has been installed in the Synchrotron Radiation Research Center (SRRC) storage ring to test the performance of the beam dynamics and photon flux behavior. A three-orthogonal Hall probe and a long-loop-coil measurement system are also implemented to take the field measurements. The multipole field and electron trajectory correction are made by shimming, the magic finger, and the active end pole coil corrector. After the field measurements, the vertical integral strength of HAPU is markedly smaller than that of the Hybrid Adjustable Gap Undulator (HAGU) and confirm that no obvious distinction arises between HAPU and HAGU in terms of the spectrum flux. The electron beam dynamic performance in the storage ring indicates that the vertical tune shift of HAPU is three times smaller than that of HAGU. Meanwhile, the energy dynamic tuning with the digital global feedback turned on, the photon position and flux in the bending chamber beam line is invariant. In addition, the injection efficiency remains unaffected at any phase position and the electron beam lifetime does not change when HAPU is in the dynamic tuning.

A 9-pole undulator prototype with a magnetic period length of 10 cm was designed and constructed to examine the mechanical and magnetic field performance. The hybrid permanent magnet structure was optimized by using 2D "PANDIRA" and 3D "TOSCA" magnetostatic codes. A half period magnet model was also fabricated to verify the magnetic field strength on-axis and the transverse field roll-off within 0.1 % in the good field region of /spl plusmn/10 mm at a minimum gap minimum gap of 22 mm. The end pole configurations, as equipped with either two tunable permanent magnetic rotators or steering coil correctors were designed for minimizing the deviation of the magnetic field strength integrals. The magnet structures were mounted on a 2 meter long C-frame support structure in which the gap could be moved in parallel and phase motion. The field characteristics and measurement results between the adjustable gap undulator (AGU) and the hybrid adjustable phase undulator (APU) were also presented.

A superconducting radio-frequency (SRF) module is commonly used for a high-energy accelerator; its purpose is to provide energy to the particle beam. Because of the low power dissipation and smaller impedance of a higher-order mode for this module, it can provide more power to the particle beam with better stability through decreasing the couple bunch instability. A RF coupler is necessary to transfer the high power from a RF generator to the cavity. A coupler of coaxial type is a common choice. With high-power operation, it might suffer from multipacting, which is a resonance phenomenon due to re-emission of secondary electrons. Applying a bias voltage between inner and outer conductors of the coaxial coupler might increase or decrease the strength of the multipacting effect. We studied the effect of a bias voltage on multipacting using numerical simulation to track the motion of the electrons. The simulation results and an application for SRF operation with a large beam current are presented in this paper.

High T c superconductor films on metal wires for high power applications must show long-term stability. Suitable buffer layers are required to prevent interaction between the superconductor thin films and the substrate, and to improve the long-term stability. A high melting-point metal, rhenium, and its oxide, were sputter deposited on the metallic substrate, Hastelloy. The study showed that rhenium thin films were resistant to out-diffusion from the Hastelloy substrates. However, it was found that they are easily oxidized at high temperature and they are, therefore, not suitable to oxygen rich high T c superconductors like YBCO. They might work with other types of high T c superconductors which have a lesser oxygen dependence.

There is evidence that atmospheric concentrations Of C0{sub 2}, tropospheric 0{sub 3}, and CH{sub 4}, among other gases that contribute to the greenhouse effect, have increased in recent decades, and that these changes may induce changes in global air temperatures and regional climate features in coming years. A literature review was conducted to sample the literature base on which our understanding of the water resource impacts of climate change rests. Water resource issues likely to be important include hydrologic response to climate change, the resilience of water supply systems to changing climatic and hydrologic conditions, and the effects of climate change on water quality and water uses (such as navigation and energy generation). A computer-assisted search of literature on the effects of climate change on these subjects was conducted. All studies were classified by type of paper (e.g., review, discussion, case study), region, water resource variable studied, and source of climate scenario. The resulting bibliography containing more than 200 references was largely annotated. Case studies of potential hydrologic impacts have been more common than studies of impacts on water management or water use, but this apparent research gap is decreasing. Case studies demonstrating methods of incorporating potential risks of climatemore » change into water project planning and management have been performed. Considerable variability in regional coverage exists; the Great Lakes basin and California receive relatively more attention than such regions as New England and the Missouri River basin. General circulation model-based and hypothetical climate scenarios have been the dominant sources of climate scenarios used in case studies, although a variety of other methods for developing climate scenarios have been developed.« less

A saturated instantaneous bandwidth (FWHM) of at least 10% in a Ka-band gyrotron traveling-wave tube (gyro-TWT) with uniform interaction waveguide and magnetic field was obtained. A relatively low alpha ( identical to nu /sub perpendicular to // nu /sub ///) beam has resulted in stable saturated operation and broad bandwidth. This, together with the overall performance of the tube (18.4-kW maximum power at 18.6% efficiency and 18-dB gain), strongly reinforces the possibility of developing a new generation of millimeter traveling-wave amplifiers based on the gyro-TWT. >

The Taiwan Light Source (TLS) is the first dedicated synchrotron light source facility that used a superconducting RF cavity to upgrade its existing RF system. More then one year has passed since the superconducting RF cavity was successfully integrated with the existing RF subsystem for routine operation. The operating status shows that the superconducting RF (SRF) system has effectively suppressed the instabilities of the beam that are caused by the interaction of the electron beam with the higher‐order‐modes of the cavity. The original goal of doubling the photon intensity has been reached by applying top‐up mode injection at the beam current of 300 mA. However, compared to the original RF system, the beam loading is much higher, and the frequency of the superconducting cavity is also more easily perturbed by the mechanical vibrations. Those make the operation of the SRF system facing the challenge on the machine reliability, especially for a dedicated synchrotron light source facility. Here we report the operating status of the SRF system, analyze the trip sources, and present our efforts to improve the machine reliability and performance since the SRF system began routine operation.

A project to replace two existing room-temperature radio frequency (RF) cavities by one CESR-III 500 MHz superconducting radio frequency (SRF) module was initiated for the Taiwan Light Source (TLS) synchrotron ring in 1999. The goals are to double the photon flux of the synchrotron light by doubling the electron beam current and to increase the stability of the electron beam by taking the advantage of the ultra-weak high-order modes (HOM) of the SRF cavity. The SRF module has been routinely operated since February 2005. The NSRRC users have benefited from a very high photon flux stability (Δ I 0 /I 0 ∼ 0.05%) that had never been achieved previously. Here, we report the initial operational experience of the SRF system.

Upon signing a technology transfer agreement with Cornell University, ACCEL began producing turn-key 500 MHz superconducting cavity systems. Five such cryomodules have been delivered and commissioned to date. Four of them are installed in accelerators for operation (two in CESR and one each in Canadian Light Source and Taiwan Light Source) and one serves as an off-line spare at CLS. One more cryomodule is scheduled for testing in early 2005. It will be a spare unit for TLS. Three cryomodules for DIAMOND Light Source are being fabricated at ACCEL. The commissioning results and operational experience with the cryomodules in CESR, CLS and TLS are presented.

A microwave electron gun system is being constructed to evaluate the feasibility of using such system as the electron source for the linac pre-injector in storage ring synchrotron radiation sources and for novel linac-based light source R&D at NSRRC. A 2856 MHz SSRL-type microwave gun cavity has been fabricated in house for this purpose. Properties of the cavity resonant modes have been characterized as a function of side-coupled cell plunger position. Special tuning plunger design for this cell allows re-adjustment of field ratio even after brazing. Field amplitude ratio of the cavity full cell to half cell has now been tuned to 2:1. That is the optimized ratio for low energy bunch compression by an alpha magnet.

In this paper, we present a computer tracking code, which can investigate the bunch length, energy spread and the threshold current of Robinson instability under the influence of the passive harmonic cavity. The effects of the radiation damping, quantum excitation and the beam loading of the harmonic cavity are included in the computation. The calculated result shows that the beam has a constant energy spread and blows up as the beam current increases from below to over the threshold current of the Robinson instability. It also indicates that the shunt impedance of the harmonic cavity is critical for whether the harmonic cavity can reach the designed goal, a stable and lengthening beam at the design beam current.

A superconducting 500‐MHz cavity module has been installed into the electron storage ring of NSRRC. This SRF module is tested on both the RF and cryogenic performances, before and after installation into the electron ring. Calibrations and measurements on its cryogenic load at different operating helium bath pressures are described and concluded. The test results of unloaded quality factor are reported. Meanwhile the excellent regulation on helium bath pressure is so advantageous to all these measurements. During normal operation with RF power, fluctuations of the helium bath pressure and liquid helium level are +/− 1.38 mbar (0.02 psi) and +/−0.2%, respectively.

An accurate and efficient de-embedding method for on-wafer device measurements at RF/microwave frequencies is presented. This method is based on transmission-line theory and does not require any physical equivalent-circuit model for external parasitic components. The propagation constant and characteristic impedance of the "THRU" dummy structure were determined to create scalable interconnect parameters for the parasitic networks connected to the three terminals of a MOSFET. Compared with the conventional scalable de-embedding method, the proposed procedure can further eliminate the unwanted parasitics from the source terminal. The performance of this new method was also validated by comparison with the "open-short" de-embedding technique.

Synchrotron motion was numerically simulated to examine the maximum stored beam current, which is limited by beam loading. In addition to the machine operating parameters, the simulation considers the influence of the phase noise of a generator voltage on the maximum stored beam current. The computed result shows that increasing the phase noise level can reduce the maximum stored beam current and the reducing of the maximum stored current, due to an increase in the noise level, escalates with increasing the cavity voltage.

A simulation that links the calculation of mechanical structure and of radio frequency electromagnetic field with the finite element code ANSYS/spl reg/ is employed in this study. Both efficiency and accuracy of the calculation are thus improved over those of the conventional computation that builds separate models with different codes for each computed domain because information related can be internally transferred between the different computation domains. The resonance frequency changes associated with mechanical properties of niobium are examined. The computed results indicate that the coefficient of thermal expansion significantly affects the shift in resonance frequency that occurs when the cavity is cooled from room temperature to liquid helium temperature. Young's modulus and Poisson's ratio have minor effects.

A high quality BaTiO/sub 3//p-Si interface was achieved at substrate temperature of 500/spl deg/C by using RF magnetron sputtering. In-situ annealing at the same temperature was carried out to study the charge behavior of BaTiO/sub 3/ films on Si substrate. Depending on the annealing oxygen pressure and annealing condition, both polarities of effective oxide charge in the metal-ferroelectric-semiconductor, Au/BaTiO/sub 3//p-Si, structure was observed. It is believed that the density of electronic states, generated at the interface due to the asymmetry of the structure between BaTiO/sub 3/ and Si substrate, and the positive oxide charges, depending on the degree of the metal-oxygen reaction for different annealing oxygen pressures and annealing durations, determines the behavior of oxide charge.

This paper presents the procedure and the formulas to analyze the effects of Landau cavity on the electron beam while the main RF system is operated on the compensated condition. It is shown that the maximal available current, determined by the phase instability limit, is reduced with Landau cavity. The model of "potential energy" is used for the calculations of the bunch length and the synchrotron frequency of the storage ring with double RF system. It is shown that the bunch length can be manipulated by tuning the resonance frequency of the passive Landau cavity, and the spread of synchrotron frequency can be induced by the addition of a Landau cavity.

A third harmonic Landau cavity with the fundamental mode of about 1.5 GHz is under development at SRRC. The cavity consists of inner copper layer and outer stainless steel layer. The vacuum-brazing process is adopted for cavity construction. The maximal power flow density on the cavity surface will be about 52.19 W/cm/sup 2/, as the total thermal loading of 32 kW. To verify the cooling capacity, the finite element method is adopted to perform the thermal and stress analyses. Under 15 m/sup 3//hr water flow rate, the temperature rise on the cavity body will be less than 14/spl deg/C, and the maximal equivalent stress on the copper layer of 29.75 N/mm/sup 2/(MPa) is achieved, which is much less than the yielding stress of copper.

When the frequency of the RF noise is close to the synchrotron frequency, it will cause longitudinal beam instability. In order to study the effect of the instability, a sinusoidal phase modulation was applied to the RF system. The beam instability was observed with a streak camera. The oscillation amplitude and frequency of the beam versus the frequency of applied phase modulation was measured. The beam splitting into two beamlets in the same RF bucket was also observed when the frequency of phase modulation was close to the synchrotron frequency.

We present here our design of the SRRC third-harmonic Landau cavity to be operated on the first stage in a passive mode for bunch lengthening so as to increase the Touschek life-time. Its implementation will also be helpful for suppression of the longitudinal coupled-bunch instabilities observed in the storage ring of SRRC. The cavity profile was optimized with the 2D code URMEL with the following criteria: (1) maximization of the shunt impedance; (2) minimization of the maximal power flow density on the cavity surface; (3) feasibility of the mechanical constructions. A prototype is now under construction.

To achieve the goals in the TLS storage ring performance upgrade plan, the necessity of adding the third RF station to the storage ring for radiation loss compensation at 1.5 GeV/350 mA operation and lifetime improvement are analyzed. We estimated the RF power required to compensate the radiation losses by bending magnets and various insertion devices. Effects of the proposed passive Landau cavity on power consumption is also studied.

A digital longitudinal damper is being developed in SRRC to stabilize the longitudinal coupled-bunch instabilities observed in the TLS storage ring. It is a bunch by bunch feedback system designed for 200 bunches at 2 ns bunch interval. Designs of the bunch phase detection circuit, the digital electronics and the 1125 MHz wideband RF system for correction of phase errors are presented in this article. The core of the digital electronics is a DSP array that utilizes commercially available DSP modules performing parallel processing at a data throughput of 500 Mbytes/sec. This will greatly reduce the time required for both hardware and software developments. A prototype operating at one eighth of the data rate of the final system is under construction to evaluate the system design.

A 1.3 GeV synchrotron radiation storage ring at SRRC has been operated for more than a year since October 1993. Starting from April 1994, the machine has been open to the user community. In February 1995, we installed a wiggler magnet of 1.8 tesla 25-pole in the ring and successfully commissioned. The machine was scheduled for the users' runs from the middle of April this year. We describe the performance of the machine without the wiggler magnet system and then report the wiggler effects on the beam dynamics of the storage ring, e.g., tune shift, beta-beating, orbit change, nonlinear dynamics effect, etc. Some measurements are compared with the model prediction and agreement between them was fairly good. Possible actions to minimize wiggler effects have been taken, such as orbit correction as a function wiggler gap change. The machine improvement projects, such as longitudinal and transverse damping systems as well as an orbit stability feedback system are under construction and will be in use soon.

As the complexity of ATM networks and Broadband ISDN (B-ISDN) services increases, network interoperability and network service integrity become major implementation issues that can not be ignored. Past experiences have demonstrated the value of vigorous network interoperability testing for the common channel signaling networks to ensure product interoperability and service integrity. Similar needs exist for the ATM networks to ensure network reliability, network performance and meeting the quality objectives for B-ISDN services. The paper describes a Bellcore effort that examined the need for a distributed ATM network services test tool for signaling testing. The paper also presents several possible test scenarios to help illustrate different applications of B-ISDN network signaling testing.

Longitudinal coupled-bunch instabilities in the SRRC 1.3 GeV storage ring have been studied by analyzing the signals picked up from the stripline electrodes and rf power reflected from the cavities. The current dependence of the instability strengths was measured. As a cross check, the bunch phase jitters as a function of beam current has also been measured by using sampling optical oscilloscope. Threshold currents of a few milliamperes have been determined from both measurements. They agree with each other very well. It is also found that the strength of the instabilities can be reduced significantly by randomly distributing electron bunches around the ring.

The 1.3 GeV storage ring at SRRC will provide an ultra-violet to soft X-ray radiation source to the potential users. The energy ramping of storage ring will push the critical photon energy to the edge of hard X-ray. There are several ways to ramp the electron energy, for example, increasing the extraction energy to 1.5 GeV from booster directly, ramping the magnets' power supplies with synchronized function generators, or asynchronized ramping of magnets at storage ring, etc. The tune drifting during the ramping procedure is expected and should be minimized such that the beam can survive through the ramping process. The betatron frequencies and ramping function of magnets were carefully monitored in order to avoid the betatron tunes cross the resonance line. A successful asynchronized ramping result will be presented in this paper.

An optimized end pole compensation scheme for the 1.8 Tesla, 25-pole wiggler W20/SRRC was studied by using 2D magneto-static code OPERA-2d. The maximum deviation of the dipole steering for this wiggler can be minimized either by optimizing the sizes of the bias magnets or by optimizing the easy-axis rotating angles of the permanent rotators. After optimization, the dipole steering is within 100 Gauss-cm in the operating gap range so that a passive compensation scheme is possible even for an insertion device configured with very strong on-axis magnetic field strength.

A coupled-field analysis process for a RF cavity structure has been established. The commercial code ANSYS is used as the solver which successfully links analyses of different fields, including electromagnetics, heat transfer, and structure mechanics. The computation efficiency is thus dramatically improved. The calculated RF characteristics of a pill-box cavity match the theoretical predictions pretty well. The following thermal and structural computation based on the surface power loss are also performed. This coupled-field analysis process has been applied to a cavity in design. The computed results associated with RF are compared to the ones calculated by other codes.

The Taiwan Light Source (TLS) is a third-generation light source with low operating energy, 1.5 GeV, which is used as ultra-violet and soft x-ray light source. A superconducting RF cavity designed by Cornell University and tested at Cornell Electron Storage Ring (CESR) will be installed at TLS. The 500 mA beam current upgrade project at TLS is expected to reach the following basic goals: (1) reducing the longitudinal coupled bunch instability, (2) increasing the stored beam current by factor of two, (3) maintaining the beam lifetime by doubling the operating gap voltage. The RF cavity and beam parameters calculation will be discussed. A calculation for radiation shielding and cryogenic safety will be presented. The HFSS simulation results for the cavity modes, components of the high-power waveguide transmission system and the coupling parameters will be addressed.

This study employs the three-dimensional magnetostatic code TOSCA to assess numerically the effects of NdFeB magnets with non-unit magnetic permeability on an elliptically polarizing undulator. A reduction of a few percent of the on-axis magnetic field strength is predicted. In addition, a deviation of ±100 G cm uncompensated dipole steering is predicted in a phase shift of 180° for the elliptically polarizing undulator EPU5.6 (having a period length of 56 mm) at the minimum gap of 18 mm, which is related primarily to the configuration of the device end scheme. Results presented herein demonstrate that implementing an active compensation mechanism is a prerequisite for minimizing the orbit distortion during phase-shift adjustment, particularly for operating such a polarizing undulator in a third-generation machine having a median energy similar to that of the 1.5 GeV storage ring at SRRC.

User requirements at SRRC for high-brilliance synchrotron light in various polarization states will be fulfilled in the near future by the implementation of two types of polarizing devices in the storage ring: the elliptically polarizing undulator (EPU) and the elliptically polarized bending magnet (EPBM). The EPBM provides a broadband polarized spectrum up to the soft X-ray range with rapid alternation of the left and right helicities. The EPU, which has a magnetic period length of 56 mm, generates a high-brilliance harmonic spectral intensity in the range 80–1400 eV with abundant polarization states, including circular ones. The optimal merit flux is evaluated for the operation of these two polarizing devices in the SRRC 1.5 GeV storage ring. The available polarization states are also surveyed.

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

The first report of the Environmental Study examines current mitigation practices for water quality [specifically, dissolved oxygen (DO)], instream flows, and upstream and downstream fish passage. This review describes information on the types and frequency of mitigations methods in use, their environmental benefits and effectiveness, and their environmental benefits and effectiveness, and their costs. Information on mitigation practices was obtained directly from three sources: (a) existing records from the Federal Energy Regulatory Commission (FERC), (b) new information provided by nonfederal hydropower developers, and (c) new information obtained from the state and federal natural resource agencies involved in hydropower regulation. Information on specific mitigation practices was obtained from 280 projects, more than 40% of all the projects licensed during the 1980s that were identified a priori as having the mitigation requirements of interest. Of all projects receiving FERC licenses or license exemptions since 1980, instream flow requirements are the most common mitigation requirement, followed by requirements for downstream fish passage, DO protection, and upstream fish passage facilities. The proportion of projects with environmental mitigation requirements has increased significantly during the past decade.