Paper | Title | Other Keywords | Page |
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MOP011 | Standing Wakefield Accelerator Based on Periodic Dielectric Structures | wakefield, simulation, electron, vacuum | 124 |
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In recent years dielectric wakefield accelerators (DWA) have attracted significant attention for applications in high energy physics and THz radiation sources. However, one needs sufficiently short driving bunches in order to take advantage of the DWA's scaling characteristics to achieve high gradient and high frequency accelerating fields. Since a single large charge Q driving bunch is difficult to be compressed to the needed rms bunch length, a driving bunch train with smaller Q and small emittance, should be used instead for the DWA. In view of this senario, the group velocity of the excited wakefields needs to be decreased to nearly zero, so the electromagnetic energy does not vacate the structure during the bunch train. In this paper we propose a standing wakefield accelerator based on periodic dielectric structures, and address the difference between the proposed structure and the conventional DWA. | |||
MOP014 | Status and Upgrades of the NLCTA for Studies of Advanced Beam Acceleration, Dynamics, and Manipulation | laser, cavity, acceleration, electron | 130 |
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The Next Linear Collider Test Accelerator (NLCTA) is a low-energy electron accelerator (120 MeV) at SLAC that is used for ultra-high gradient X-band RF structure testing and advanced accelerator research. Here we give an overview of the current program at the facility, including the E-163 direct laser acceleration experiment, the echo-enabled harmonic generation (EEHG) FEL experiment, narrow-band THz generation, coherent optical transition radiation (COTR) studies, microbunching instability studies, and X-band structure testing. We also present the upgrades that are currently underway and some future programs utilizing these upgrades, including extension of the EEHG experiments to higher harmonics, and an emittance exchange experiment. | |||
MOP057 | A SLAB Dielectric Structure as a Source of Wakefield Acceleration and THz Cherenkov Radiation Generation | wakefield, acceleration, simulation, electron | 211 |
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Funding: Work is funded by US Dept. of Energy grant numbers DE-FG03-92ER40693. Acceleration of electrons in wakefields set up by a series of drive bunches in a dielectric structure has been proposed as a possible component of next-generation accelerators. Here, we discuss future experimental work with a slab sub-millimeter dielectric loaded accelerator structure that in contrast to conventional dielectric tubes should diminish the effects of transverse wakes and will permit higher total charge to be accelerated. The proposed experiment will allow the generation of unprecedented peak power at THz frequencies. In addition, it can generate ~50-150 MV/m drive fields and thus will allow the testing of acceleration using witness and drive beams. We examine details of the geometry and composition of the structures to be used in the experiment. |
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MOP071 | Terahertz Light Source and User Area at FACET | electron, photon, linac, site | 238 |
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Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET at SLAC provides high charge, high peak current, low emittance electron beam that is bunched at THz wavelength scale during its normal operation. A THz light source based coherent transition radiation (CTR) from this beam would potentially be the brightest short-pulse THz source ever constructed. Efforts have been put into building this photon source together with a user area, to provide a platform to utilize this unique THz radiation for novel nonlinear and ultrafast phenomena researches and experiments. |
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MOP094 | Development of Advanced Beam Halo Diagnostics at the Jefferson Lab Free-Electron-Laser Facility | electron, FEL, laser, monitoring | 274 |
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Funding: Many colleagues at JLab FEL provided help with the installation of the present experimental setup. This work is partially supported by DOE Contract DE-AC05-060R23171. High average current and high brightness electron beams are needed for many applications. At the Jefferson Lab FEL facility, the search for dark matter with the FEL laser beam has produced interesting results*, and a second very promising method for dark matter search using JLab Energy-recovery-linac (ERL) machine has been put forward**. Although the required beam current has been achieved on this machine, one key challenge is the management of beam halo. UMD has demonstrated a high dynamic range halo measurement method using a digital micro-mirror array device. A similar system has been established at JLab FEL facility as a joint effort by UMD and JLab to measure the beam halo on the high current ERL machine***. The experiment and characterization are being performed while the new UV FEL is running for optimization. In this paper, the limitations of the current system will be analyzed and study of other approaches (such as an optimized coronagraph) for further extending measuring dynamic range will be presented. In particular, we will discuss in detail the possibility of performing both longitudinal and transverse (3D) halo measurement altogether on one single system. * A. Afanasev, et al., PRL. 101 120401 (2008). ** J. Thale, Searching for a New Gauge Boson at JLab, Newport News, VA, September 20-21, 2010 *** H. Zhang, et al., this conference. |
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MOP102 | High-Gradient High-Energy-Gain Inverse Free Electron Laser Experiment using a Helical Undulator | laser, undulator, electron, simulation | 289 |
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Funding: UC Lab fee award 09-LR-04-117055-MUSP DOE-HEP grant DE-FG02-92ER40693 Defense Threat Reduction Agency, Basic Research Award # HDTRA1-10-1-0073 Preparations for a high energy gain inverse free electron laser (IFEL) experiment using an undulator and Brookhaven National Lab’s (BNL) Accelerator Test Facility’s (ATF) terawatt CO2 laser are underway. 3D simulations suggest that the experiment will likely accelerate a 50 MeV beam to 117 MeV in 54 cm while maintaining a low energy spread. The helical undulator is currently under construction at UCLA’s Particle Beam Physics Laboratory. |
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MOP121 | Experimental Studies on Coherent Synchrotron Radiation in the Emittance Exchange Line at the Fermilab A0 Photoinjector | emittance, synchrotron, dipole, synchrotron-radiation | 322 |
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Future accelerators will employ advanced beam conditioning systems such as emittance exchangers to manipulate high brightness beams. Coherent synchrotron radiation (CSR) in the dipoles could limit the performance of the emittance exchanger. In this paper, we report the experimental and simulation studies on measuring coherent synchrotron radiation and its effects on the beam at the A0 photoinjector in the emittance exchange line. We show how CSR can be used to measure bunch length of the beam. We also report on the diagnostic scheme based on a weak skew quad in the emittance exchange line to study the CSR effects on the beam and other beam dynamics. | |||
MOP136 | Coupler Studies for PBG Fiber Accelerators | coupling, laser, simulation, lattice | 346 |
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Funding: U.S. Dept. of Energy contract DE-AC02-76SF00515 Photonic band gap (PBG) fibers with hollow core defects are being designed and fabricated for use as laser driven accelerators because they appear capable of providing gradients of several GeV/m at picosecond pulse lengths. While we expect to have fiber down to 1.5-2.0 micron wavelengths we still lack a viable means for efficient coupling of laser power into these structures. The reasons for this include the very different character of these TM-like modes from those familiar in the telecom field and the fact that the defect must function as both a longitudinal waveguide for the accelerating field and a transport channel for the particles. We discuss the status of our coupling work in terms of what has been done and the options we are pursuing for both end and side coupling. In both basic coupler types, the symmetry of the PBG crystal leads to significant differences between this and the telecom field. We show that side coupling provides more possibilities and is preferred. Our motivation is to test new fiber for gradient, mode content and throughput on the NLCTA at SLAC. |
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MOP159 | Ionization-Induced Trapping in Laser-Plasma Accelerators and Synchrotron Radiation from the Betatron Oscillation | electron, laser, injection, simulation | 394 |
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Funding: This work is supported by the U.S. DOE Office of High Energy Physics under Contract No. DE-AC02-05CH11231, and NNSA, NA-22, and used the computational resources of NERSC. Ionization injection into a laser wakefield accelerator is studied by multi-dimensional particle-in-cell (PIC) simulations. To obtain low energy spread beams we use a short region of gas mixture (H+N) near the start of the stage to trap electrons, while the remainder of the stage uses pure H and is injection-free. Effects of gas mix parameters, including concentration and length of the mixture region, on the final electron injection number and beam quality are studied. Two dimensional PIC simulations show the injected electron beam has filament structures in the plane perpendicular to the laser polarization direction in early time and this structure disappears later due to the betatron oscillation of the electrons in the wakefield. Synchrotron radiation from the accelerated electrons is calculated by a post processing code - Virtual Detector for Synchrotron Radiation (VDSR). |
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MOP162 | Betatron Radiation from an Off-axis Electron Beam in the Plasma Wakefield Accelerator | plasma, electron, betatron, ion | 400 |
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Funding: supported by US DoE In the non-linear or blow-out regime of a plasma wakefield, the electrons of the accelerated bunch oscillate in a pure ion column. It was demonstrated that a single bunch can emit betatron radiation in the keV to MeV range*. In a drive/witness bunch system, the witness bunch can be injected into the ion column with a transverse momentum or initial radial offset, so that the whole bunch oscillates about the column axis as one marcro-electron. This results in a larger emitted power and higher photon energy. The energy loss due to radiation can be compensated for by the energy gain from the wakefield so that the emission process can be sustained over long distance. Detailed results will be presented about the characteristics of the witness bunch oscillations and radiation through numerical simulations** and calculations. * S.Q. Wang, et al., Phys. Rev.Let., 88(13), 135004,(2002), D. K. Johnson et al., Phys. Rev. Lett. 97(17), 175003, (2006) ** C.H. Huang, et al., J. Comp. Phys., 217(2), 658, (2006) |
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MOP179 | Numerical Study on Zone Plate Imaging | electron, synchrotron, optics | 423 |
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Funding: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science and Technology (MEST) (grant No. R0A-2008-000-20013-0). The X-ray is focused by two zone plates in 1B2 beamline to image electron beam in PLS. From numerical study, we can determine the optical limit of resolution with the same specifications of Fresnel zone plates in 1B2 beamline. The width of Airy pattern and the outmost width of zone plates are turned out to be not good parameters to determine the resolution of the imaging system with a zone plate. The resolution of the entire imaging system 1B2 beamline will be revealed as 682 nm. |
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MOP185 | Development of Longitudinal Beam Profile Diagnostics within DITANET | target, electron, diagnostics, ion | 435 |
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Funding: Work supported by the EU under contract PITN-GA-2008-215080. The exact determination of the time structure of ever shorter bunches in accelerators and light sources such as for example the X-FEL, the ILC or CLIC is of high importance for the successful operation of these next-generation machines. It is also a key to the optimization of existing scientific infrastructures. The exact measurement of the time structure poses a number of challenges to the beam diagnostics system: The monitors should be non-destructive, easy to maintain and provide time resolutions down to the femtosecond regime. Several DITANET partners are active in this field. This contribution gives examples of the network’s research activities in this area with a focus on the LHC longitudinal density monitor, beam profile monitoring using electro-optics techniques and the exploitation of diffraction radiation for non-invasive diagnostics. |
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MOP189 | Progress in the Development of a Grazing-incidence Insertion Device X-ray Beam Position Monitor | undulator, background, insertion, insertion-device | 441 |
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Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Recently, a grazing-incidence insertion device x-ray beam position monitor (GRID-XBPM) was proposed for the intense x-ray beam from the future APS undulators [*]. By combining the function of limiting aperture with the XBPM, it increases the power-bearing capacity of the XBPM and, at the same time, eliminates the problem of relative alignment of the two critical components in the beamline. Furthermore, by imaging the hard x-ray fluorescence footprint on the collimator, the XBPM is immune to the soft x-ray background, and its accuracy is improved at larger gap settings. In addition to these advantages, the GRID-XBPM can also be implemented to measure center-of-mass of the x-ray fluorescence footprint when pinhole-camera-like optics are used for position readout*. This offers a solution for long-standing XBPM design issues for elliptical undulators, which have a donut-shaped power distribution. In this work, we report design progress for the GRID-XBPM for the high-power elliptically polarized undulator planned for the APS intermediate energy x-ray (IEX) beamline. Computer simulation of its performance and experimental tests from a scale model system will also be presented. * B.X. Yang, G. Decker, S. H. Lee, and P. Den Hartog, Beam Instrumentation Workshop, Santa Fe, 2010, to be published. |
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MOP192 | NSLS-II BPM System Protection from Rogue Mode Coupling | shielding, vacuum, multipole, synchrotron | 450 |
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Funding: Work supported by DOE contract DE-AC02-98CH10886 Rogue mode RF shielding has been successfully designed and implemented into the production multipole vacuum chambers. In order to avoid systematic errors in the NSLS-II BPM system we introduced frequency shift of HOM's by using RF metal shielding located in the antechamber slot of each multipole vacuum chamber. To satisfy the pumping requirement the face of the shielding has been perforated with roughly 50 percent transparency. It stays clear of synchrotron radiation in each chamber. |
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MOP193 | Design of Visible Diagnostic Beamline for NSLS2 Storage Ring | synchrotron, diagnostics, electron, storage-ring | 453 |
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A visible synchrotron light monitor (SLM) beam line has been designed at the NSLS2 storage ring, using the bending magnet radiation. A retractable thin absorber will be placed in front of the first mirror to block the central x-rays. The first mirror will reflect the visible light through a vacuum window. The light is guided by three 6" diameter mirrors into the experiment hutch. In this paper, we will describe design work on various optical components in the beamline. | |||
MOP199 | NSLS-II X-ray Diagnostics Development | diagnostics, optics, electron, wiggler | 468 |
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NSLS-II storage ring will have less then 1nm*rad emittance. A concept of X-ray diagnostics beamline was developed in order to measure small sizes of radiation sources to deduct beam emittance. Diagnostics will include pinhole cameras and Compound Refractive Lens focusing optics. A novel optical layout was suggested in order to measure sources with large horizontal to vertical aspect ratio. | |||
MOP208 | Baseline Suppression Problems for High Precision Measurements Using Optical Beam Profile Monitors. | background, controls, brightness, monitoring | 486 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The use of fluorescent screens for beam profile monitors provides a simple and widely used way to obtain detailed two dimensional intensity maps. For high precision measurements many possible error contributions need to be considered that have to do with properties of the fluorescent screens and of the CCDs. Saturation effects, reflections within and outside the screen, non-linearities, radiation damage, etc are often mentioned. Here we concentrate on an error source less commonly described, namely erroneous baseline subtraction, which is particularly important when fitting projected images. We show computer simulations as well as measurement results having remarkable sensitivity of the fitted profile widths to even partial suppression of the profile baseline data, which often arises from large pixel-to-pixel variations at low intensity levels. Such inadvertent baseline data suppression is very easy to miss as it is usually not obvious when inspecting projected profiles. In this report we illustrate this effect and discuss possible algorithms to automate the detection of this problem as well as some possible corrective measures. |
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MOP219 | Initial Beam-Profiling Tests with the NML Prototype Station at the Fermilab A0 Photoinjector | emittance, optics, diagnostics, target | 510 |
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Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Beam-profile diagnostics are being developed for a superconducting (SC) radiofrequency (RF) Test Accelerator that is currently under construction at the New Muon Lab (NML) at Fermilab. The facility’s design goals include the replication of the pulse train proscribed for the International Linear Collider (ILC). An RF photoelectric gun based on the DESY design will generate the beam. In test-beam mode a low-power beam will be characterized with intercepting radiation converter screens: either a 100-micron thick YAG:Ce single crystal scintillator or a 1-micron thin Al optical transition radiation (OTR) foil. This prototype station was constructed by RadiaBeam Technologies under a contract with Fermilab. In both cases the screen surface was normal to the beam direction followed by a downstream 45-degree mirror that directed the radiation into the optical system. The optical system has better than 20 (10) micron rms spatial resolution when covering a vertical field of view of 18(5) mm. These initial tests were performed at the A0 Photoinjector at a beam energy of ~15 MeV and with micropulse charges from 25 to 500 pC for beam sizes of 45 to 250 microns. Example results will be presented. |
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MOP220 | The Feasibility of Near-Field ODR Beam-Size Monitoring at 23 GeV at FACET | polarization, monitoring, simulation, booster | 513 |
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Funding: Work partially supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam- size sensitivity at the 10- to 20- μm σ level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year. |
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MOP241 | Beam Diagnostics for FACET | plasma, diagnostics, electron, linac | 565 |
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Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23 GeV, 3 nC electron bunches compressed to ~20 μm long and focussed to ~10 μm wide. Characterization of the beam- plasma interaction requires complete knowledge of the incoming beam parameters on a pulse-to- pulse basis. FACET diagnostics include Beam Position Monitors, Toroidal current monitors, X-ray and Cerenkov based energy spectrometers, optical transition radiation (OTR) profile monitors and coherent transition radiation (CTR) bunch length measurement systems. The compliment of beam diagnostics and their expected performance are reviewed. |
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MOP272 | Radiation Dose Level in the SSRF during Normal Operation | monitoring, neutron, storage-ring, injection | 615 |
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Shanghai Synchrotron Radiation Facility (SSRF) has been commissioned since December 2007, and has been formally operated since May 2009. In order to ensure the radiation safety for staff members and publics, the radiation levels of the workplace, the environment and the staff are monitored through a real-time network of gamma and neutron monitors as well as through TLD passive dosimeters. This paper reports the results of the radiation monitoring. From these results, we found that the annual dose equivalents were good to meet the management values of SSRF. | |||
MOP273 | Calibration and Simulation of the LCLS Undulator Beam Loss Monitors using APS Accelerators | simulation, electron, undulator, photon | 618 |
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Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02-06CH11357 Electrons scattered by alumina ceramic transverse beam profile monitors inserted in the Advanced Photon Source (APS) booster-to-storage ring (BTS) transfer line are used to generate C ̆erenkov light for calibration of beam loss monitors (BLMs) installed in the Linac Coherent Light Source (LCLS) undulator beamline. In addition, gas bremsstrahlung (GB) photons generated by 7-GeV electrons in the APS sector 35 storage ring straight section are used to create pair-production electrons for measurement and calibration purposes. Both cases are modeled with the particle-matter interaction program MARS. The realized tuning fork geometry of the BLM exhibits regions of greater sensitivity in the radiator. Transverse GB beam scans have provided uniformity and sensitivity data throughout the volume of the radiator. Comparisons between predicted and measured signal strengths and thermoluminescent dosimeter readings are given and shown to be in reasonable agreement. |
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MOP274 | Beam Loss Monitors for NSLS-II Storage Ring | electron, injection, shielding, dipole | 621 |
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Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886 The shielding for the NSLS-II storage ring will provide adequate protection for the full injected beam losses in two periods of the ring around the injection point, but the remainder of the ring is shielded for lower losses of <10% top-off injection beam current. This will require a system to insure that beam losses do not exceed these levels for a period of time that could cause excessive radiation exposure outside the shield walls. This beam Loss Control and Monitoring system will have beam loss monitors that will measure where the beam charge is lost around the ring, to warn operators if losses approach the design limits. In order to measure the charge loss quantitatively, we propose measuring the electron component of the shower as beam electrons hit the vacuum chamber wall. This will be done using the Cerenkov light as charged particles transit an ultra-pure fused silica rod placed close to the inner edge of the VC. The length of rod will collect the light from many charged particles of the spread out shower resulting from the small glancing angle of the lost beam particles to the VC wall. The design and measurements results of the prototype Cerenkov BLM will be presented. |
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MOP288 | Progress Report on Development of the RING Cavity for Laser-based Charge Stripping of Hydrogen Ions | neutron, laser, ion, recirculation | 657 |
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Charge stripping of hydrogen ions is the first stage of any high intensity proton accelerator. To achieve higher-charge proton sources, the stripping efficiency must be improved, especially in the context of the Spallation Neutron Source at Oak Ridge National Laboratory. A method based on laser-ion interaction has a great potential for increasing efficiency. The approach of this proposed project is to design a laser cavity based on the Recirculation Injection by Nonlinear Gating (RING) technique. This paper reports on the progress of the development of the RING cavity. | |||
TUOAS1 | Tutorial on Accelerator-Based Light Sources | electron, emittance, dipole, undulator | 702 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Accelerator-based light sources are some of the largest and most successful scientific user facilities in existence, serving tens of thousands of users each year. These important facilities enable research in diverse fields, including biology, pharmaceuticals, energy conservation and production, data storage, and archaeology. In this tutorial, we briefly review the history of accelerator-based light sources. We present an overview of the different types of accelerator-based light sources, including a description of their various operating principles, as well as a discussion of measures of performance. Technical challenges of current and future light sources are also reviewed. |
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Slides TUOAS1 [1.421 MB] | |||
TUOBS3 | Status of the NSLS-II Project | vacuum, storage-ring, injection, photon | 732 |
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NSLS-II, the new 3 GeV 3rd generation light source presently under construction at Brookhaven National Laboratory will provide ultra-bright synchrotron radiation of 1021 photons s-1 mm-2 mrad-2 0.1% BW-1 at 2keV and high photon flux of 1015 photons s-1 0.1% BW-1. The facility will support a minimum of 60 beamlines. Construction started in 2009 and commissioning is expected to be completed in 2014. This report will provide a description of the NSLS-II design and will summarize the status of the construction project. | |||
Slides TUOBS3 [7.560 MB] | |||
TUOCS2 | Accelerator Aspects of the Advance Photon Source Upgrade | undulator, photon, lattice, brightness | 766 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is a third-generation storage-ring-based x-ray source that has been operating for more than 13 years and is enjoying a long period of stable, reliable operation. While APS is presently providing state-of-the-art performance to its large user community, we must plan for improvements and upgrades to stay at the forefront scientifically. Significant improvements should be possible through upgrades of beamline optics, detectors, and end-station equipment. In this paper, we discuss the evolutionary changes that are envisioned for the storage ring itself. These include short-pulse x-rays, long straight sections, superconducting undulators, improved beam stability, and higher current. With these and other changes, we anticipate significant improvements in capacity, flux, and brightness, along with the ability to perform unique time-resolved experiments. |
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Slides TUOCS2 [0.932 MB] | |||
TUODN1 | CSR Fields From Using a Direct Numerical Solution of Maxwell's Equations | vacuum, synchrotron, synchrotron-radiation, dipole | 784 |
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Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515. We discuss the properties of the coherent electromagnetic fields of a very short, ultra-relativistic bunch in a rectangular vacuum chamber inside a bending magnet. The analysis is based on the results of a direct numerical solution of Maxwell’s equations together with Newton’s equations. We use a new dispersion-free time-domain algorithm which employs a more efficient use of finite element mesh techniques and hence produces self-consistent and stable solutions for very short bunches. We investigate the fine structure of the CSR fields including coherent edge radiation. This approach should be useful in the study of existing and future concepts of particle accelerators and ultrafast coherent light sources. |
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Slides TUODN1 [8.690 MB] | |||
TUODS5 | Optics-free X-ray FEL Oscillator | FEL, electron, undulator, feedback | 802 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. There is a need for an Optics-Free FEL Oscillators (OFFELO) to further the advantages of free-electron lasers and turning them in fully coherent light sources. While SASE (Self-Amplified Spontaneous Emission) FELs demonstrated the capability of providing very high gain and short pulses of radiation and scalability to the Xray range, the spectra of SASE FELs remains rather wide (~0.5%-1%) compared with typical short wavelengths FEL-oscillators (0.01% - 0.0003% in OK-4 FEL). Absence of good optics in VUV and X-ray ranges makes traditional oscillator schemes with very high average and peak spectral brightness either very complex or, strictly speaking, impossible. In this paper, we discuss lattice of the X-ray optics-free FEL oscillator and present results of initial computer simulations of the feedback process and the evolution of FEL spectrum in X-ray OFFELO. We also discuss main limiting factors and feasibility of X-ray OFFELO. |
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Slides TUODS5 [1.401 MB] | |||
TUP033 | Engineering Design of Vertical Test Stand Cryostat | vacuum, cavity, shielding, instrumentation | 874 |
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Under Indian Institutions and Fermilab collaboration Raja Ramanna Centre for Advanced Technology and Fermi Lab are jointly developing 2K Vertical Test Stand (VTS) cryostats for testing SCRF cavities. The VTS cryostat has been designed for a large testing aperture of 34 inches for testing of 325 MHz Spoke resonators, 650 MHz and 1.3 GHz multi-cell SCRF cavities for Project-X at FNAL and for VTS facility at RRCAT. VTS cryostat comprises of liquid helium (LHe) vessel with internal magnetic shield, top insert plate equipped with cavity support stand and radiation shield, liquid nitrogen (LN2) shield and vacuum vessel with external magnetic shield. . The engineering design and analysis of VTS cryostat has been carried out using ASME B&PV code and FEA. Design of internal and external magnetic shields was performed to limit the magnetic field inside LHe vessel, at the cavity surface <10 mG. Thermal analysis for LN2 shield has been performed to check the effectiveness of LN2 cooling. | |||
TUP162 | Engineering Design of HTS Quadrupole for FRIB | quadrupole, pick-up, vacuum, factory | 1124 |
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Funding: Supported by the U.S. Department of Energy under Contract DE-AC02-98CH10886 and under Cooperative Agreement DE-SC0000661 from DOE-SC that provides financial assistance to MSU for FRIB. The coils of the first quadrupole in the fragment separator region of the Facility for Rare Isotope Beams (FRIB) must withstand an intense level of radiation and accommodate a very high heat load. Magnets produced with High Temperature Superconductors (HTS) are especially suitable in such an environment. The proposed design employs second generation (2G) HTS, permitting operation at ~50K. The engineering considerations this design are summarized. The goal has been to engineer a compact, readily producible magnet with a warm bore and yoke, made from radiation-resistant materials, capable of operating within the heat load limit, whose four double-layered coils will be adequately restrained under high radial Lorentz forces. Results of ANSYS finite element thermal and structural analyses of the coil clamping system are presented. Coil winding, lead routing and splicing, magnet assembly as well as remote tunnel installation/removal considerations are factored into this design and will also be discussed. |
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TUP165 | Design, Construction and Test of Cryogen-Free HTS Coil Structure | vacuum, instrumentation, quadrupole, superconducting-magnet | 1133 |
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Funding: Work supported by the U.S. Dept. of Energy under Contract No. DE-AC02-98CH10886 & under Coop. Agreement DE-SC0000661 from DOE-SC that provides financial assistance to MSU to design and establish FRIB This paper will describe design, construction and test results of a cryo-mechanical structure to study coils made with the second generation High Temperature Superconductor (HTS) for the Facility for Rare Isotope Beams (FRIB). A magnet comprised of HTS coils mounted in a vacuum vessel and conduction-cooled with Gifford-McMahon cycle cryocoolers is used to develop and refine design and construction techniques. The study of these techniques and their effect on operations provides a better understanding of the use of cryogen free magnets in future accelerator projects. A cryogen-free, superconducting HTS magnet possesses certain operational advantages over cryogenically cooled, low temperature superconducting magnets. |
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TUP171 | Influence of Proton Irradiation on Angular Dependence of Second Generation (2G) HTS | proton, quadrupole, target, superconductivity | 1145 |
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Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-98CH10886 and under Cooperative Agreement DE-SC0000661 from DOE-SC that provides financial assistance to MSU to design and establish FRIB. In the Facility for Rare Isotope Beams (FRIB), superconducting magnets will be exposed to high levels of ionizing radiation. Quadruples in the fragment separator will be exposed to radiation doses as high as ~20 MGy/yr and heat loads as high as ~10 kW/m. High temperature superconducting (HTS) tapes are good candidates for this magnet because they can be operated in the temperature range ~30-50 K to tolerate higher temperatures than low temperature superconductors. Thus, radiation damage studies of HTS tapes are crucial to ensure that they will perform satisfactorily in such a high radiation environment. Therefore, the effects of proton irradiation on second generation HTS tapes from two vendors were studied. Each sample of HTS tape from SuperPower and American Superconductor was irradiated by a 42μA, 142 MeV proton beam at the Brookhaven Linac Isotope Producer. Two of each were irradiated at 5 dose levels: 2.5, 25, 50, 75 and 100μA•hr. The angular dependence of the critical current was measured in a magnetic field at 77K. Based on these measurements, conductors from both vendors appear to satisfy the FRIB radiation-tolerance requirement of 10 years of operation. |
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TUP173 | Progress on the Modeling and Modification of the MICE Superconducting Spectrometer Solenoids | solenoid, simulation, emittance, focusing | 1151 |
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Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231. The Muon Ionization Cooling Experiment (MICE) is an international effort sited at Rutherford Appleton Laboratory (RAL) in the UK that will demonstrate ionization cooling in a section of realistic cooling channel using a muon beam. The spectrometer solenoids are an identical pair of five-coil superconducting magnets that will provide a 4-tesla uniform field region at each end of the cooling channel. Scintillating fiber trackers within each of the 400-mm diameter magnet bore tubes will measure the emittance of the beam as it enters and exits the cooling channel. Each of the 3-meter long magnets incorporates a three-coil spectrometer magnet section and a two-coil section that matches the solenoid uniform field into the MICE cooling channel. The cold mass, radiation shield and leads are kept cold by means of a series of two-stage cryocoolers and one single-stage cryocooler. Various thermal, electrical and magnetic analyses are being carried out in order to develop design improvements related to magnet cooling and reliability. The key features of the spectrometer solenoid magnets are presented along with some of the details of the analyses. |
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TUP177 | Open Midplane Dipoles for a Muon Collider | dipole, collider, storage-ring, luminosity | 1160 |
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Funding: This work is supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886 and SBIR contract DOE Grant Numbers DE-FG02-07ER84855 and DE-FG02-08ER85037. For a muon collider with copious decay particles in the plane of the storage ring, open-midplane dipoles (OMD) may be preferable to tungsten-shielded cosine-theta dipoles of large aperture. The OMD should have its midplane completely free of material, so as to dodge the radiation from decaying muons. Analysis funded by a Phase I SBIR suggests that a field of 10-20 T should be feasible, with homogeneity of 1x10-4 and energy deposition low enough for conduction cooling to 4.2 K helium. If funded, a Phase II SBIR would refine the analysis and build and test a proof-of-principle magnet. |
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TUP216 | Design of a Helium Phase Separator with Condenser | cryogenics, vacuum, synchrotron, synchrotron-radiation | 1214 |
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This paper presents the design of a helium phase separator with volume of 100 litres. A condenser using a cryocooler for cooling is built into the phase separator to save liquid helium consumption during the test period. The heat loss to the 4.2 K inner vessel is confined within 1W due to the limited 1.5W cooling capacity from the cryocooler. Analysis of mechanical strength and heat load is illustrated. | |||
TUP224 | Cryogenic Vertical Test Facility for the SRF Cavities at BNL | vacuum, cryogenics, SRF, shielding | 1238 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy A vertical facility has been constructed to test SRF cavities and can be utilized for other use. The liquid helium volume for the large vertical dewar is approximate 84 inches tall by 40 inches diameter with a working clear inner diameter of 38 inch with the inner cold magnetic shield system installed. For radiation enclosure, the test dewar is situated inside a concrete block structure. The structure is above ground and is accessible from the top, and has a retractable concrete roof. A second radiation concrete facility, with ground level access via a labyrinth is also available for testing of smaller cavities in 2 smaller dewars. |
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TUP227 | Status of NSLS-II Storage Ring Vacuum Systems | vacuum, photon, multipole, dipole | 1244 |
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Funding: Work performed under the auspices of U.S. Department of Energy, under contract DE-AC02-98CH10886 National Synchrotron Light Source II (NSLS-II), being constructed at Brookhaven National Laboratory, is a 3- GeV, high-flux and high-brightness synchrotron radiation facility with a nominal current of 500 mA. The storage ring vacuum system has extruded aluminium chambers, with ante-chamber for photon fans and distributed NEG strip pumping. Discrete photon absorbers are used to intercept the un-used bending magnet radiation. In-situ bakeout is implemented to achieve fast conditioning during initial commissioning and after interventions. |
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TUP230 | In-situ Secondary Electron Yield Measurement System at CesrTA | electron, gun, photon, vacuum | 1253 |
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Funding: Work Supported by NSF Grant #PHY-0734867 & DOE Grant #DE-FC02-08ER41538 Measuring the secondary electron yield (SEY) on technical surfaces in accelerator vacuum systems provides essential information for the study of electron cloud growth and suppression, with application to many accelerator R&D projects. As a part of the CesrTA research program, we developed and deployed an in-situ SEY measurement system. A two-sample SEY system was installed in the CesrTA vacuum system with one sample exposed to direct synchrotron radiation (SR) and the other sample exposed to scattered SR. The SEYs of both samples were measured as a function of the SR dosages. In this paper, we describe the in-situ SEY measurement systems and the initial results on bare aluminum (6061-T6), TiN-coated aluminum, amorphous carbon-coated aluminum, and amorphous carbon-coated copper samples. |
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TUP237 | Development of Accurate and Precise In-Vacuum Undulator System | vacuum, undulator, coupling, simulation | 1268 |
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Typical in-vacuum undulators, especially long ones, have several associated engineering challenges to be accurate and precise; magnetic centerline stability, inner girder hangers, and magnet period to name a few. The following describes these issues in more detail and ADC’s methods solved these critical issues for long in vacuum undulators. ADC has designed, built and delivered Insertion Devices and Magnetic Measurement Systems to such facilities as; MAXLab (EPU, Planar-2, and Measurement System), ALBA and Australian Synchrotron Project (Wiggler), BNL (Cryo In-Vacuum), SSRF (In-Vacuum – 2, and Measurement System), PAL (In-Vacuum and Measurement System), NSRRC (In-Vacuum), and SRC (Planar and EPU). The information presented here uses data from a recent IVU we delivered to PAL. This IVU will be installed at Pohang Accelerator Laboratory (PAL) for U-SAXS (Ultra Small Angle X-ray Scattering) beamline in 2011. The IVU generates undulator radiation up to ~14 keV using higher harmonic (up to 9th) undulator radiation with 2.5 GeV PLS electron beam | |||
TUP240 | Coil Energizing Patterns for an Electromagnetic Variably Polarizing Undulator | polarization, undulator, wiggler, emittance | 1277 |
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Funding: The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). A new electromagnetic insertion device optimized for producing intense soft x-rays of variable polarization is under construction at the Advanced Photon Source. Most of the coil packs are powered by a main power supply; a few are powered separately so that magnetic fields at certain pole positions can be different. The undulator radiation depends sensitively on the chosen magnetic field pattern, and higher spectral harmonics may be shifted in energy. For some beamline experiments, it is important to reduce the so-called higher-order contamination to increase the signal-to-noise ratio. We present spectra and power densities calculated directly from realistic magnetic fields and discuss coil energizing patterns. Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. |
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TUP245 | Comparison of Standard S-Glass and Ceramic Coating as Insulation in Short-Period Superconducting Undulators Based on Nb3Sn | undulator, factory | 1292 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This paper compares calculated on-axis fields for short- period superconducting undulators (SCUs) using Nb3Sn superconductor with two different insulation thicknesses, 0.02 mm and 0.05 mm. When the insulated conductor diameter remained the same, the on-axis fields using the thinner insulation were higher by about 8 – 15% for a period range of 15 – 10 mm. When the conductor diameters with the thicker insulation were made larger than the conductors with the thinner insulation, the differences were reduced to be about 6 – 12%. |
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TUP248 | SC Undulator with the Possibility To Change Its Strength and Polarization by Feeding Current | undulator, polarization, electron, vacuum | 1295 |
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Funding: NSF We describe the design of optimized undulator with SC windings able to generate the magnetic field of opposite helicities, including an elliptic and a linear ones oriented as desired. For the undulator period 25mm and aperture 8mm, K factor could be changed from zero up to 1.5 by changing the feeding current. Polarization changed by changing the currents in additional helical windings. |
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TUP286 | Development and Testing of Carbon Fiber Vacuum Chamber Supports for NSLS-II | alignment, pick-up, vacuum, laser | 1364 |
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The NSLS-II Synchrotron Light Source, a 3 GeV electron storage ring currently under construction at Brookhaven National Laboratory is expected to provide exceptional orbit stability in order to fully utilize the very small emittance of the electron beam. In order to realize this, the beam position monitor (BPM) pick up electrodes which are part of the orbit feedback system must have a high degree of mechanical and thermal stability. In the baseline design, this would be accomplished by using flexible invar plates to support the multi-pole vacuum chamber at the positions where the BPM pick up electrodes are mounted. However, it was later discovered that the close proximity of the invar supports to the adjacent focusing magnets had an adverse affect on the magnetic fields. To mitigate this issue, we propose the use of carbon fiber composite in place of invar as a low CTE (coefficient of thermal expansion) material. Here we show the design, development and testing of thermally stable composite supports capable of sub-micron thermal stability. | |||
WEOCN5 | Beam Halo Measurements at UMER and the JLAB FEL Using an Adaptive Masking Method | FEL, quadrupole, electron, synchrotron | 1449 |
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Funding: US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences and by the Dept. of Defense Office of Naval Research and Joint Technology Office. Beam halo is a challenging issue for intense beams since it can cause beam loss, emittance growth, nuclear activation and secondary electron emission. Because of the potentially low number of particles in the halo compared with beam core, traditional imaging methods may not have sufficient contrast to detect faint halos. We have developed a high dynamic range, adaptive masking method to measure halo using a digital micro-mirror array device and demonstrated its effectiveness experimentally on the University of Maryland Electron Ring (UMER). We also report on similar experiments currently in progress at the Jefferson Lab Free Electron Laser (FEL) using this method. |
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Slides WEOCN5 [1.287 MB] | |||
WEOCN6 | Femtosecond Resolved Determination of Electron Beam and XUV Seed Pulse Temporal Overlap in sFLASH | electron, laser, undulator, simulation | 1452 |
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sFLASH is a seeded experiment at the Free-Electron Laser FLASH in Hamburg. It uses a 38nm High-Harmonic-Generation (HHG) scheme to seed the FEL-process in a 10 m long variable-gap undulator. The temporal overlap between the electron and HHG pulses is critical to the seeding process. The use of a 3rd harmonic accelerating module provides a high current electron beam with ~400 fs bunch duration. The duration of the HHG laser pulse is ∼20 fs. The desired overlap is achieved in two steps. Firstly, the HHG drive laser is synchronized to the incoherent spontaneous radiation from an upstream undulator with picosecond resolution. Next, the coherent radiation from an undulator is used to determine the exact overlap of the electron beam in a modulator-radiator set-up. | |||
Slides WEOCN6 [1.758 MB] | |||
WEOCS1 | Development of Long Nb3Sn Quadrupoles by the US LHC Accelerator Research Program | quadrupole, luminosity, collider, alignment | 1455 |
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Insertion quadrupoles with large aperture and high gradient are required to upgrade the luminosity of the Large Hadron Collider (HL-LHC). The US LHC Accelerator Research Program (LARP) is a collaboration of DOE National Laboratories aiming at demonstrating the feasibility of Nb3Sn magnet technology for this application. Several series of magnets with increasing performance and complexity have been fabricated, with particular emphasis on addressing length scale-up issues. Program results and future directions are discussed. | |||
Slides WEOCS1 [4.433 MB] | |||
WEODS2 | High-Power Targets: Experience and R&D for 2 MW | target, proton, neutron, simulation | 1496 |
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High-power particle production targets are crucial elements of future neutrino and other rare particle beams. Fermilab plans to produce a beam of neutrinos (LBNE) with a 2.3 MW proton beam (Project X). Any solid target is unlikely to survive for an extended period in such an environment - many materials would not survive a single beam pulse. We are using our experience with previous neutrino and antiproton production targets, along with a new series of R&D tests, to design a target that has adequate survivability for this beamline. The issues considered are thermal shock (stress waves), heat removal, radiation damage, radiation accelerated corrosion effects, physics/geometry optimization and residual radiation. | |||
WEP021 | The Effect of Initial Energy Spread on Longitudinal Beam Modulations in an Electron Gun | electron, gun, cathode, simulation | 1537 |
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Computer simulations are used to investigate the evolution of longitudinal density and energy modulations of an electron beam in a linear accelerator system. This study examines the effect of initial energy spread on the modulations as the beam is accelerated in the electron gun. | |||
WEP108 | Application of Coherent Tune Shift Measurements to the Characterization of Electron Cloud Growth | simulation, electron, photon, vacuum | 1680 |
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Funding: DOE = DE-FC02-08ER41538 NSF = PHY-0734867 Measurements of coherent tune shifts at the Cornell Electron Storage Ring Test Accelerator (CesrTA) have been made for electron and positron beams under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of several electron cloud simulation programs allows the evaluation of important parameters in these models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders. We outline recent improvements to the analysis techniques that should improve the fidelity of the modeling. |
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WEP119 | Coherent Radiation in Whispering Gallery Modes | vacuum, resonance, impedance, synchrotron | 1710 |
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Funding: Work at SLAC: U.S. Department of Energy Contract No. DE-AC03-76SF00515 Work at CLS: NSERC, NRC, Province of Saskatchewan, U. of Saskatchewan. Theory predicts that CSR in storage rings should appear in whispering gallery modes *, which are resonances of the entire vacuum chamber and are characterized by their high frequencies and concentration of the field near the outer wall of the chamber. The theory assumes that the chamber is a smooth circular torus. We observe that a power spectrum from the NSLS-VUV ring **, which has a vacuum chamber in bends like that of the model, shows a series of sharp peaks with frequencies close to those of the theory. Sharp peaks are also seen in highly resolved spectra at the Canadian Light Source***, and those are invariant in position under large changes in the machine setup (energy, fill pattern, bunch length, CSR bursting or steady, optical beam line, etc.). Invariance of the spectrum suggests that it is due to resonances like whispering gallery modes, but they must be strongly perturbed from the circular case because of large outer wall excursions at the two IR ports. * R. L. Warnock and P. Morton, Part. Accel. 25, 113 (1990). ** G. L. Carr et al., Proc. PAC 2001, Chicago. *** T. May et al., IEEE 33rd Intl. Conf. IR Millimeter and THz Waves, 2008. |
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WEP126 | Progress in Experimental Study of Current Filamentation Instability | plasma, vacuum, simulation, electron | 1719 |
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Funding: Work supported by Department of Energy and National Science Foundation Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas. CFI could play an important role in the generation of magnetic fields and radiation in the after-glow of gamma ray bursts and also in energy transport for the fast-igniter inertial confinement fusion concept. Simulations were conducted with the particle-in-cell code QuickPIC* for e- beam and plasma parameters at the Brookhaven National Laboratory – Accelerator Test Facility, BNL-ATF. Results show that for a 2cm plasma the instability reaches near saturation. An experimental program was proposed and accepted at the BNL-ATF and an experiment is currently underway. There are three components to the experimental program: 1) imaging of the beam density/filaments at the exit from the plasma, 2) measurement and imaging of the transverse plasma density gradient and measurement of the magnetic field and 3) identifying the radiation spectrum of the instability. Preliminary results from phase one will be presented along with the progress and diagnostic design for the following phases of the experiment. * C. Huang et. al. Journal of Computational Physics 217, 2(2006) |
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WEP140 | Benchmarking Stepwise Ray-Tracing in Rings in Presence of Radiation Damping | damping, emittance, lattice, synchrotron | 1746 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A number of recent machine designs, including ‘‘nano-beams'', sub-millimeter ‘‘low-beta'' IRs, etc., require high accuracy on beam orbit and beam size, reliable evaluation of machine parameters, dynamic apertures, etc. This can only be achieved using high precision simulation tools. Stepwise ray-tracing methods are in this category of tools, stochastic synchrotron radiation and its effects on an electron beam in a storage ring are simulated here in that manner. Benchmarking of the method against analytical model expectations, using a Chasman-Green cell, is presented. |
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WEP173 | Numerical Calculations for the SR Characteristics Described in Terms of Quantum Theory: The Case of Weakly Excited Particles. | polarization, synchrotron, electron, synchrotron-radiation | 1810 |
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We present the numerical calculations based on the theoretical research of SR characteristics for the weakly excited particles. For a spinless and spinor particle the exploration of effective angles and deviation angles is to be conducted. Comparing the data obtained with its classical analogue , one shows that the quantum theory gives a number of unpredictable results. | |||
WEP181 | Coherent Radiation in Insertion Devices | undulator, vacuum, wiggler, FEL | 1828 |
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Funding: NSF We calculate the coherent radiation in an undulator/wiggler with a vacuum chamber of arbitrary cross section. The backward radiation is a coherent and it has wavelengths about twice the period of the undulator/wiggler. Mostly of coherent radiation is going with the wavelengths approximately the bunch length at small angles however. |
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WEP184 | Cerenkov Radiator Driven by a Superconducting RF Electron Gun | gun, electron, simulation, SRF | 1831 |
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Funding: Parts of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The Naval Postgraduate School (NPS), Niowave, Inc., and Boeing have recently demonstrated operation of the first superconducting RF electron gun based on a quarter wave resonator structure. In preliminary tests, this gun has produced 10 ps-long bunches with charge in excess of 78 pC, and with beam energy up to 396 keV. Initial testing occurred at Niowave's Lansing, MI, facility, but the gun and its diagnostic beamline are planned for installation at NPS in the near future. The design of the diagnostic beamline is conducive to the addition of a Cerenkov radiator without interfering with other beamline operations. Design and simulations of a Cerenkov radiator, consisting of a dielectric lined waveguide will be presented. The dispersion relation for the structure is determined and the beam interaction is studied using numerical simulations. The characteristics of the microwave radiation produced in both the long and short bunch regimes will be examined. |
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WEP189 | Compression and Synchronization of an Ultra-short Electron Beam Using a THz Undulator Interaction | undulator, laser, electron, injection | 1843 |
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Funding: DOE-BES No. DE-FG02-92ER40693 and DOE-BES No. DE-FG02-07ER46272 Injection of electron beams into laser driven picosecond scale accelerating structures demand highly synchronized electron beams with bunch lengths approaching the femtosecond scale. One-dimensional numerical studies of undulator interactions of 3.5 MeV sub-picosecond electron beams and THz pulse trains produced by optical rectification have shown substantial compression and a reduction in time of arrival jitter with respect to the accelerator drive laser from the scale of hundreds of fs to that of tens of fs. In this paper a THz undulator based compression and synchronization scheme is investigated. |
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THOAS2 | Solid State RF Power - The route to 1W per Euro Cent | electron, klystron, linac, synchrotron | 2047 |
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In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of power sources based on electron beams i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive technology [*,**,***] at unprecedented efficiency, power levels and power densities. The proposed solutions allows retrofitting of existing RF solutions and opens the route to novel accelerator designs.
* Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan ** Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA *** Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan |
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Slides THOAS2 [1.776 MB] | |||
THP003 | High Power THz FEL Source Based on FFAG Betatron | FEL, electron, betatron, extraction | 2142 |
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A novel source of high power sub-mm waves is proposed that combines two well-known technologies – a betatron induction FFAG accelerator and a free electron laser (FEL). The system is configured as an FEL oscillator: the electron beam circulates in bi-periodic FFAG lattice and the external optical resonator maintains beam-radiation overlap through multiple orbits. Initial analysis shows that FEL gain and very high extraction efficiency are possible with modest injected beam current. A simplified interaction model and preliminary analysis results are presented. | |||
THP010 | Optimization of Dual Scattering Foil for 6 to 20 MeV Electron Beam Radiotherapy | electron, scattering, simulation, target | 2157 |
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From last 50 years, electron beam therapy has an important radiation therapy modality. The electron beam from the LINAC is of size ~ 2 mm, whereas the size required for actual treatment is usually larger than 2 X 2 cm2 up to 30 X 30 cm2 at the isocenter. In the present work, it is proposed to use dual scattering foil system for production of clinical electron beam. The foils for 6 to 20 MeV electrons were optimized using the Monte Carlo based FLUKA code. The material composition, thickness of primary foil, Gaussian width and thickness of secondary foil were optimized such that it should meet the design parameters such as Dose at iso-center, beam uniformity, admixture of bremsstrahlung, etc. A pencil beam of electrons passing through primary foil converted into Gaussian shape and falling at the centroid of secondary foil which experienced maximum scattering, whereas falling at the edge experienced the minimum scattering. This results into flat profile of electron at isocenter. In conclusion, the primary scattering foil has been optimized with high Z element (Ta) having uniform thickness, whereas the secondary foil has been optimized with low Z element (Al) having Gaussian shape. | |||
THP016 | Design of an Achromatic and Uncoupled Medical Gantry for Radiation Therapy | quadrupole, optics, dipole, controls | 2163 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We are presenting the layout and the optics of a beam line to be used as a medical gantry in radiation therapy. The optical properties of the gantry’s beam line are such as to make the beam line achromatic and uncoupled. These two properties make the beam spot size, which is delivered and focused by the gantry, on the tumor of the patient, independent of the angular orientation of the gantry. In this paper we present the layout of the magnetic elements of the gantry, and also present the theoretical basis for the optics design of such a gantry. * N. Tsoupas et. al. “Uncoupled achromatic tilted S-bend” Presented at the 11th Biennial European Particle Accelerator Conference, Genoa, Italy, June 23-27,2008 |
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THP020 | Effects of 6 MeV Electron Irradiation on ZnO Nanoparticles Synthesized by Microwave Method | electron, microtron, factory, lattice | 2166 |
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The sizes of zinc-oxide (ZnO) nanoparticles were synthesized by microwave method and were tailored by electron irradiation method. The ZnO nanoparticles having size of ~46 nm synthesised by microwave method were exposed to different fluences of 6 MeV electrons over the range from 1x1015 to 2.5x1015 e- /cm2. The electron irradiated ZnO nanoparticles were characterized by XRD, SEM, UV techniques. The XRD results show that the particle size reduced continuously from 46 nm to 15 nm with the increase in electron fluence and SEM images also confirms the formation of nanoparticles of minimum size of around 14 nm. The band gap of the ZnO nanoparticle also increased from 3.29 to 3.42 eV as the size reduced. The result shows the ZnO particles are broken in to smaller size under electron irradiation and increase in the band gap indicates the formation of defects in ZnO. The electron irradiation method is found to be an efficient method in tailoring the size of ZnO nano particles. The nanosized ZnO particles can suit for the applications such as photovoltaics, photocells and antimicrobial activity. | |||
THP029 | Temperature and Optimize Design of Beam Window in the Accelerator | proton, target, neutron, vacuum | 2175 |
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Careful evaluation of the heat-transfer and corresponding problems is important in the beam window in the design and operation of Accelerator Driven sub-critical System (ADS). Using the Monte-Carlo code Fluka, we studied the energy deposition of the beam window in high power proton accelerator. The temperature distribution of the beam window is calculated in presence of the coolant. The process of computation for various materials will be introduced, and an optimized design scheme is given. The results suggest that some measures could be used to reduce the damage to the beam window, such as dividing current into branch currents, expanding the bunch or using beryllium as the material of the beam window, et al. | |||
THP045 | Proposed Facility Layout for MaRIE | electron, laser, proton, undulator | 2202 |
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The MaRIE (Matter-Radiation Interactions in Extremes) experimental facility will be used to advance materials science by providing the tools scientists need to develop materials that will perform predictably and on demand for currently unattainable lifetimes in extreme environments. The Multi-Probe Diagnostic Hall (MPDH) will create probes of matter using both photon- and proton-based diagnostics. The Fission and Fusion Materials Facility (F3) will provide capabilities for materials irradiation studies, subjecting materials to radiation extremes that are present in fission and fusion environments. The Making, Measuring, and Modeling Materials (M4) Facility will foster discovery by design of next-generation materials that will perform with better durability in extreme environments. MaRIE features a 20-GeV electron linac for an X-ray driver. Five X-ray beams will be delivered to the experimental areas. The facility will also deliver an electron beam to MPDH. The existing LANSCE proton beam will be delivered to MPDH and F3 in addition to the existing LANSCE areas. Multiple high power lasers will deliver beams to MPDH. This paper will provide an overview of the MaRIE facility layout. | |||
THP048 | Radiation and Thermal Analysis of Production Solenoid for Mu2e Experimental Setup | solenoid, target, neutron, proton | 2208 |
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The Muon-to-Electron (Mu2e) experiment at Fermilab, will seek the evidence of direct muon to electron conversion that cannot be explained by the Standard Model. An 8 GeV 25 kW proton beam will be directed onto a gold target inside a large-bore superconducting Production Solenoid (PS) with the peak field on the axis of ~5T. The negative muons resulting from the pion decay will be captured in the PS aperture and directed by an S-shaped Transport Solenoid towards the stopping target inside the Detector Solenoid. In order for the superconducting magnets to operate reliably and with a sufficient safety margin, the peak neutron flux entering the coils must be reduced by 3 orders of magnitude that is achieved by means of a sophisticated absorber placed in the magnet aperture. The proposed absorber, consisting of W and Cu parts, is optimized for the performance and cost. Results of MARS15 of energy deposition and radiation analysis are reported. The results of the PS magnet thermal analysis, coordinated with the coil cooling scheme, are reported as well for the selected absorber design. | |||
THP085 | Radiation Effects in a Muon Collider Ring and Dipole Magnet Protection | dipole, quadrupole, collider, lattice | 2294 |
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Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Requirements and operating conditions for a Muon Collider Ring (MCR) pose significant challenges to superconducting magnets. The dipole magnets should provide a high magnetic field to reduce the ring circumference and thus maximize the number of muon collisions during their lifetime. One third of the beam energy is continuously deposited along the lattice by the decay electrons at the rate of 0.5 kW/m for a 1.5-TeV c.o.m. MCR. Unlike dipoles in proton machines, the MCR dipoles should allow this dynamic heat load to escape the magnet helium volume in horizontal plane predominantly towards the ring center. Two alternative designs, one based on the open mid-plane approach with block type coils and absorber outside the coils, and another based on the traditional large-aperture cos-theta approach with a shifted beam pipe and absorber inside the coil aperture were developed for the MCR designed for a luminosity of 1034 cm-2s−1. This paper presents the analysis and comparison of radiation effects in MCR based on the two dipole magnets. Tungsten masks in the interconnect regions are used in both cases to mitigate the unprecedented dynamic heat deposition and radiation in the magnet coils. |
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THP108 | Analysis of RHIC Beam Dump Pre-fires | high-voltage, kicker, survey, secondary-beams | 2327 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. It has been speculated that the beam may cause instability of the RHIC Beam Abort Kickers. In this study, we explore the available data of past beam operations, the device history of key modulator components, and the radiation patterns to examine the correlations. |
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THP122 | Comparison of Chirp Schemes for Short-Pulse X-ray Beams in Light Sources | electron, photon, insertion, insertion-device | 2348 |
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Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357. The Advanced Photon Source is planning [*] to produce a short-pulse x-ray beam by way of rf deflecting cavities that locally impose a y'-t correlation on the stored beam at an insertion device. SPring-8 recently proposed [**] a variation on this scheme whereby the deflecting cavities impose a local y-t correlation on the stored beam. In one case the chirp is in the angle coordinate and in the other case the position coordinate. They both use slits to pass through a "short" portion of the photon beam. The practical limitations for the two schemes are discussed and compared, such as photon source size and angular divergence, storage ring apertures, and slit transmission. * A. Nassiri et al., these proceedings ** T. Fujita et al., Proc. of IPAC10, p. 39 |
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THP126 | Obtaining Sub-Picosecond X-Ray Pulses in the Advanced Photon Source Using Laser Slicing | laser, electron, wiggler, photon | 2357 |
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 The laser slicing technique* has been successfully applied at several low- to medium-energy storage ring light sources to create sub-picosecond pulses of x-rays. Application to high-energy storage rings has been considered problematic because of the required average laser power. However, because of on going advances in laser technology, this technique is now within reach at light sources like the Advanced Photon Source (APS), which operates at 7 GeV. In this paper, we analyze the potential performance of laser slicing at the APS, and compare it to alternatives such as deflecting cavities. * R. W. Schoenlien et al., Science, 287, 2237(2000). |
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THP140 | Synchrotron Light Options at Super-B | brightness, photon, undulator, synchrotron | 2384 |
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The Super-B facility will collide electron and positron beams with different characteristics as done in the past at PEP-II and KEKB. The ring and electron (positron) beam characteristic of both high and low energy rings of the Super-B are comparable to NSLS-II and other state of the art synchrotron light sources. This suggests the use of this facility, either parasitically or in dedicated runs, as light source. In this paper we compare the characteristics of the synchrotron light generated at Super-B with existing, in construction and proposed facilities. We investigate different schemes to incorporate the generation of synchrotron radiation in the collider lattice design and look at different beam line layouts for users. | |||
THP144 | FELs as X-ray Sources in ERL Facilities | FEL, emittance, electron, linac | 2390 |
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Funding: This work has been supported by NSF award DMR-0807731. Hard x-ray Energy Recovery Linacs (ERLs) operate with high-brightness electron beams, matching the requirements for X-ray FELs in terms of emittance and energy spread. We have analyzed in how far it is feasible to include X-ray FELs in ERL facilities. X-ray FEL Oscillators require comparatively low peak currents and are therefore good candidates for FEL sources in ERLs. However, also high-gain FELs do not seem out of reach when bunch-compression schemes for higher peak currents are utilized. Using the proposed Cornell ERL as an example, different FEL concepts are discussed and their suitability as X-ray sources are analyzed. |
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THP146 | Preliminary Study of Terahertz Free-Electron Laser Oscillator Based on Electrostatic Accelerator | FEL, cavity, electron, undulator | 2393 |
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Since the terahertz radiation sources provide wide applications in medical, industrial and material science, a compact, wavelength tunable and high-power THz source attracted much attention in many laboratories. In this paper, we give a primary study of a compact THz FEL based on electrostatic accelerator and the choice of basic design parameters is presented. The feasibility study is carried out using FELO codes. It is proved that FEL utilizing electrostatic accelerators (EA-FEL) will be a promising compact and powerful terahertz source. | |||
THP148 | Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier | undulator, laser, electron, simulation | 2396 |
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We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high- gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering.
* T. Watanabe et al, Phys. Rev. Lett. 98, 034802 (2007). ** X.J. Wang et al, Phys. Rev. Lett. 103, 154801 (2009). |
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THP149 | Amplification of Current Density Modulation in a FEL with an Infinite Electron beam | electron, FEL, free-electron-laser, laser | 2399 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We show that the paraxial field equation for a free electron laser (FEL) in an infinitely wide electron beam with a kappa-2 energy distribution can be reduced to a fourth ordinary differential equation (ODE). Its solution for arbitrary initial phase space density modulation has been derived in the wave-vector domain. For initial current modulation with Gaussian profile, close form solutions are obtained in space-time domain. |
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THP152 | Calibration of Spectrometers with Undulator Radiation | undulator, electron, FEL, photon | 2402 |
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Funding: This work is supported in part by the U.S. Department of Energy, Office of Nuclear Physics under grant number DE-FG02-97ER41033 A well-calibrated spectrometer is critical for measuring the real spectra of spontaneous radiation of an electron beam in undulators (i.e. undulator radiation), which is important for FEL research. A calibration method of spectrometers based upon the known undulator radiation spectrum has been developed at Duke FEL Laboratory (DFELL). It has been used to provide a precise calibration for spectrometers from infrared (IR) to ultraviolet (UV). This calibration method is expected to be useful for the calibration of spectrometers working in the extreme ultraviolet (EUV) and X-ray region. In this work, we present the details of the calibration method and illustrate the usefulness of the method using a portable spectrometer in the visible region as an example. |
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THP155 | Experience of FEL Mirror Degradation at the Duke FEL and HIGS Facility | FEL, wiggler, cavity, laser | 2408 |
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Funding: This work is supported by the US DoE grant #DE-FG02-97ER41033 The Duke FEL and High Intensity Gamma-ray Source (HIγS) are operated in the range of electron beam energies of 0.24 - 1.2 GeV and photon beam wavelengths of 190-1060 nm. The range of gamma-beam energies currently produced by HIγS facility is from 1MeV to about 100 MeV, with the maximum total gamma-flux of up to 3*1010 gammas per second around 10 MeV. Production of this high level gamma-ray flux requires an average FEL photon beam power inside the FEL resonator at one kilowatt or more. The high power FEL operation causes degradation of the FEL mirrors, especially when operating the FEL in the UV and VUV region at a high electron beam energy. To ensure reliable HIγS operation, we developed a comprehensive program to continuously monitor the performance of the FEL mirrors. This program enabled us to use a particular set of FEL mirrors for a few hundreds hours of high gamma-flux operation with predictable performance. In this work, we discuss sources and consequences of the mirror degradation for a variety of wavelengths. We also present estimates of the mirror life time as a function of the FEL wavelength, photon and gamma-ray polarization, and total gamma-flux. |
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THP170 | Observation and Characterization of Coherent Optical Radiation and Microbunching Instability in the SLAC Next Linear Collider Test Accelerator | laser, undulator, electron, FEL | 2426 |
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The NLC Test Accelerator (NLCTA) at SLAC is currently configured for a proof-of-principle echo-enabled harmonic generation (EEHG) experiment using a 120 MeV beam. During commissioning, unexpected coherent optical undulator radiation (CUR) and coherent optical transition radiation (COTR) was observed when beam is accelerated off-crest and compressed after the chicanes. The CUR and COTR is likely due to a microbunching instability where initial small modulations in the cathode drive laser pulse are compressed and amplified. In this paper we present the observation and characterization of the CUR, COTR and microbunching instability at NLCTA.
* D. Xiang et al., "Demonstration of the Echo-Enabled Harmonic Generation Technique for Short-Wavelength Seeded Free Electron Lasers", PRL 105, 114801, 2010. |
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THP174 | A Single Cavity Echo Scheme | cavity, undulator, electron, simulation | 2438 |
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Funding: This work was supported by the DIrector, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The possibility of implementing echo-enabled harmonic generation* (EEHG) within a single optical resonance cavity is explored both analytically and with numerical simulations. Two modulators of the same frequency are used so that the cavity radiation replaces the two seed lasers of conventional EEHG. Such a scheme has potential** to produce tunable radiation as in EEHG, but with the high repetition rate, longitudinal coherence, and narrow spectral bandwidth of an oscillator. These benefits, however, come with the complication that the beam must generate the radiation that modulates it. Analysis and GINGER simulations are presented for a specific example that takes advantage of robust multilayer mirror performance at 13.4 nm to produce radiation near or possibly even below 1 nm. * G. Stupakov, Phys. Rev. Lett. 102, 074801 (2009). ** J. Wurtele et al., Proc. of the 2010 FEL Conference, TUOC12. |
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THP181 | Low Intensity Nonlinear Effects in Compton Scattering Sources | electron, laser, scattering, photon | 2453 |
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The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. In particular, while it is known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. |
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