Keyword: wiggler
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MOP003 Six-Dimensional Bunch Merging for Muon Collider Cooling emittance, kicker, simulation, collider 109
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
  
  A muon collider requires single, intense, muon bunches with small emittances in all six dimensions. It is most efficient to initally phase-rotate the muons into many separate bunches, cool these bunches in six dimensions (6D), and, when cool enough, merge them into single bunches (one of each sign). Previous studies only merged in longitudinal phase space (2D). In this paper we describe merging in all six dimensions (6D). The scheme uses rf for longitudinal merging, and kickers and transports with differing lengths (trombones) for transverse merging. Preliminary simulations, including incorporation in 6D cooling, is described.  
 
MOP182 Measurement of the Energy Dependence of Touschek Electron Counting Rate scattering, electron, background, polarization 426
 
  • I.B. Nikolaev, V.E. Blinov, V.A. Kiselev, S.A. Nikitin, V.V. Smaluk
    BINP SB RAS, Novosibirsk, Russia
  
  We have measured a dependence of the intra-beam scattering rate on the VEPP-4M beam energy and compared it with our theoretical estimates. Measurements have been performed at several energy points in a wide range: from 1.85 up to 4.0 GeV.  
 
MOP199 NSLS-II X-ray Diagnostics Development diagnostics, optics, radiation, electron 468
 
  • P. Ilinski
    BNL, Upton, Long Island, New York, USA
  
  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.  
 
TUOCN1 Accurate Computation of Transfer Maps for Realistic Beamline Elements from Surface Data dipole, multipole, electron, damping 742
 
  • C.E. Mitchell
    NRL, Washington, DC, USA
  • A. Dragt
    UMD, College Park, Maryland, USA
  
  The behavior of orbits in charged-particle beam transport systems, including both linear and circular accelerators as well as final focus sections and spectrometers, can depend sensitively on nonlinear fringe-field and high-order-multipole effects in the various beam-line elements. The inclusion of these effects requires a detailed and realistic model of the interior and fringe fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional field data on a grid, as provided by various 3-dimensional finite-element field codes. Based on these realistic field models, Lie or other methods may be used to compute accurate design orbits and accurate transfer maps about these orbits. This talk will provide a description of the methods along with example applications. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.  
slides icon Slides TUOCN1 [1.630 MB]  
 
TUOCS6 An VUV FEL for Producing Circularly Polarized Compton Gamma-ray Beams in the 70 to 100 MeV Region FEL, electron, cavity, storage-ring 778
 
  • Y.K. Wu, J.Y. Li, S.F. Mikhailov, V. Popov, G. Swift, P.W. Wallace, W. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • S. Huang
    PKU/IHIP, Beijing, People's Republic of China
  
  Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
Recently, the Duke optical klystron FEL (OK-5 FEL) has been commissioned to produce lasing in the VUV region (191 - 193 nm), overcoming substantial laser cavity loss due to low reflectivity of the VUV FEL mirrors. With two OK-5 FEL wigglers separated by more than 20 meters in a non-optimal configuration, an adequate FEL gain was realized by operating the Duke storage ring with a high single-bunch current (30 to 50 mA). This VUV FEL has enabled us to produce circularly polarized Compton gamma-ray beams in the 70 to 100 MeV region at the High Intensity Gamma-ray Source (HIGS), Duke University. This high energy gamma-ray beam capability will create new opportunities for both fundamental and applied research at HIGS. In this work, we report our experience of VUV FEL lasing with a high single-bunch current and first production of gamma-ray beams in the 70 to 100 MeV region. 		 
slides icon Slides TUOCS6 [2.768 MB]  
 
TUP232 Super-Conducting Wigglers and the Effect on Injection Efficiency injection, simulation, storage-ring, betatron 1259
 
  • M.J. Sigrist, L.O. Dallin, W.A. Wurtz
    CLS, Saskatoon, Saskatchewan, Canada
  
  The Canadian Light Source has two superconducting wigglers (SCW) operating at 2.1T and 4.3T peak fields. Injection efficiency into the storage ring is reduced by either device operating at high fields. Currently the CLS operates with a Fill and Decay mode, injecting with both wigglers at reduced field to avoid low injection efficiencies. Future implementation of a Top-up mode will require both wigglers to be operating at full field and better injection efficiencies will be required. Simulations and experiments have shown that the poor injection efficiency is related to operating a high vertical chromaticity. Much improved efficiencies are observed at when the chromaticity is lowered. As well, small improvements to the injection efficiency have been achieved through local correction of the beta-beats and tune shifts caused by the wigglers and optimisation of the injection co-ordinates of the injected beam. Measurements of the injection efficiencies at various chromaticities will be presented along with the betatron oscillations before and after correction.  
 
TUP236 Progress of a Gradient Damping Wiggler of the ALPHA Storage Ring dipole, damping, storage-ring, electron 1265
 
  • C.W. Huang, D.J. Huang
    NTHU, Hsinchu, Taiwan
  • S.D. Chen
    NCTU, Hsinchu, Taiwan
  • M.-H. Huang, C.-S. Hwang, C.Y. Kuo, F.-Y. Lin, Y.T. Yu
    NSRRC, Hsinchu, Taiwan
  • S.-Y. Lee
    IUCF, Bloomington, Indiana, USA
  
  The main purpose of a gradient damping wiggler (GDW) to be installed in the Alpha storage ring in Indiana University is to correct the momentum-compaction factor and the damping partition in the Alpha storage ring. One middle pole and two outer poles in one set of the GDW are installed on the same girder. Two sets of GDW will be installed in the two short straight sections. The dipole and gradient-field strengths of the middle (outer) pole are 0.67 T (-0.67 T) and 1.273 T m-1 (1.273 T m-1), respectively. One completed set of GDW is already fabricated; we shall add an end shim to improve the region of effective good field within which the middle and outer poles along the transverse x-axis (△B/B = 0.1 %) are ±50 and ±40 mm respectively. We used a trim coil on the three poles to adjust the first and second integral fields to zero. Here we discuss the integral magnetic field features along the straight trajectory and the ideal orbital trajectory with a Hall probe mapping system, and present an analysis of the magnetic field.  
 
TUP240 Coil Energizing Patterns for an Electromagnetic Variably Polarizing Undulator polarization, undulator, emittance, radiation 1277
 
  • R.J. Dejus, M.S. Jaski, E.R. Moog
    ANL, Argonne, USA
  • S. Sasaki
    HSRC, Higashi-Hiroshima, Japan
  
  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.
 		 
 
TUP243 Development Status of a Magnetic Measurement System for the APS Superconducting Undulator undulator, status, cryogenics, photon 1286
 
  • Y. Ivanyushenkov, M. Abliz, C.L. Doose, M. Kasa, E. Trakhtenberg, I. Vasserman
    ANL, Argonne, USA
  • V.K. Lev, N.A. Mezentsev, V.M. Tsukanov
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Short-period superconducting undulators are being developed as part of the Advanced Photon Source (APS) upgrade program. The first test device is in fabrication. Before installation into the storage ring, the magnetic performance of the undulators will be characterized. The magnetic measurement facility routinely used for measuring and tuning conventional undulators cannot be employed for superconducting devices, so a new measurement system is being designed and built. The system is mechanically mounted on the undulator cryostat and uses a heated tube in the cold undulator bore to guide a Hall probe or measuring coils. A specially designed three-Hall sensor assembly allows measurement of the vertical and horizontal components of the magnetic field and the determination of the height of the magnetic midplane. A set of measuring coils is mounted on carbon-fiber tubes that can be translated and rotated in the undulator bore to measure the field integrals and their multipole components. The design of the measurement system and its construction status is described in this paper. 		 
 
WEOCN4 Electron Beam Diagnostics of the JLab UV FEL FEL, linac, electron, cavity 1446
 
  • P. Evtushenko, S.V. Benson, G.H. Biallas, J.L. Coleman, C. Dickover, D. Douglas, M. Marchlik, D.W. Sexton, C. Tennant
    JLAB, Newport News, Virginia, USA
  
  In this contribution we describe various systems of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line of existing 10kW IR Upgrade FEL. Here we describe a set of the following systems. A combination of OTR and phosphor viewers used for measurements of a transverse beam profile, transverse emittance, Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurements system is used to setup bunch compression in an optimal way such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of the diagnostics system made its contribution to achieve the first lasing of the FEL after about 60 hours of beam operation.  
slides icon Slides WEOCN4 [8.864 MB]  
 
WEP064 Beam Dynamics Study of the Intermediate Energy X-Ray Wiggler for the Advanced Photon Source simulation, undulator, magnet-design, electron 1594
 
  • A. Xiao, M. Borland, L. Emery, M.S. Jaski, V. Sajaev
    ANL, Argonne, USA
  
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An intermediate-energy x-ray (IEX) helical wiggler is planned for the APS storage ring. Because of its high field and rapid field roll-off, the disturbance to the beam dynamics is large and needs to be well understood before the installation. We present a new method of fitting the magnetic field to an analytical wiggler model, which simplifies the usual nonlinear fitting problem and guarantees the best fit. The fitting method was validated by comparison to an analytical method. 		 
 
WEP066 Tracking Code Developement for Beam Dynamics Optimization lattice, simulation, damping, dynamic-aperture 1600
 
  • L. Yang
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Dynamic aperture (DA) optimization with direct particle tracking is a straight forward approach when the computing power is permitted. It can have various realistic errors included and is more close than theoretical estimations. In this approach, a fast and parallel tracking code could be very helpful. In this presentation, we describe an implementation of storage ring particle tracking code TESLA for beam dynamics optimization. It supports MPI based parallel computing and is robust as DA calculation engine. This code has been used in the NSLS-II dynamics optimizations and obtained promising performance. 		 
 
WEP181 Coherent Radiation in Insertion Devices radiation, undulator, vacuum, FEL 1828
 
  • A.A. Mikhailichenko
    CLASSE, Ithaca, New York, USA
  • E.G. Bessonov
    LPI, Moscow, Russia
  
  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. 		 
 
THOBN3 Proof-of-Principle Experiment for FEL-based Coherent Electron Cooling electron, FEL, hadron, ion 2064
 
  • V. Litvinenko, I. Ben-Zvi, J. Bengtsson, A.V. Fedotov, Y. Hao, D. Kayran, G.J. Mahler, W. Meng, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, S.D. Webb, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • G.I. Bell, D.L. Bruhwiler, B.T. Schwartz
    Tech-X, Boulder, Colorado, USA
  • A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer
    JLAB, Newport News, Virginia, USA
  
  Funding: This work is supported the U.S. Department of Energy
Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders*. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using one of JLab’s SRF cryo-modules. In this paper, we describe the experimental setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC.
* Vladimir N. Litvinenko, Yaroslav S. Derbenev, Physical Review Letters 102, 114801 		 
slides icon Slides THOBN3 [1.379 MB]  
 
THOBS1 Developments in Superconducting Insertion Devices undulator, photon, electron, storage-ring 2077
 
  • E.R. Moog, Y. Ivanyushenkov
    ANL, Argonne, USA
  
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A number of superconducting wigglers are installed and in operation worldwide. Superconducting undulators, with their shorter periods and more demanding field quality requirements, present additional challenges and are still under development. Superconducting technology can produce a higher magnetic field strength on the beam axis than can a permanent-magnet-based undulator. This makes shorter period undulators feasible – they will still reach high enough field to have a reasonable photon energy tuning range. The shorter period device gives higher photon brightness at higher photon energies, opening up new opportunities for photon-hungry applications that require higher photon energies. Many light sources are interested in having a superconducting undulator; a few, including the Advanced Photon Source, have ongoing projects and are making significant progress. The status of these projects will be discussed. 		 
slides icon Slides THOBS1 [3.427 MB]  
 
THOBS4 Current Status of Insertion Device Development at the NSLS-II and its Future Plans undulator, insertion, insertion-device, vacuum 2090
 
  • T. Tanabe, O.V. Chubar, T.M. Corwin, D.A. Harder, P. He, C.A. Kitegi, G. Rakowsky, J. Rank, C. Rhein, C.J. Spataro
    BNL, Upton, Long Island, New York, USA
  
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH1-886 with the U.S. Department of Energy.
National Synchrotron Light Source-II (NSLS-II) project is currently under construction. Procurement of various insertion devices (IDs) has begun. IDs in the project baseline scope include six 3.5m long damping wigglers (DWs) with 100mm period, two 2.0m Elliptically Polarizing Undulator (EPU) with 49mm period, two 3.0m-20mm period IVUs and one 1.5m-21mm IVU. Recently a special device for inelastic X-ray scattering beamline has been added to the collection of baseline devices. This is a special wide pole IVU with 22mm period for a long straight section. Three pole wigglers with 28mm gap and peak field over 1T will be utilized for NSLS bending magnet users. Examples of R&D work for future devices are: 1) Development of in-vacuum magnetic measurement system (IVMMS), 2) Use of new type of magnet such as PrFeB for improved performance on cryo-permanent magnet undulator (CPMU), 3) Development of closed loop He gas refrigerator with a linear motor actuator, 4) Adaptive gap undulator (AGU) 5) Various field measurement technique improvement. Design features of the baseline devices, ID-Magnetic Measurement Facility and the future plans for NSLS-II ID activities are described. 		 
slides icon Slides THOBS4 [4.171 MB]  
 
THP043 High-performance Accelerators for Free-Electron Laser (FEL) and Security Applications FEL, gun, electron, emittance 2196
 
  • A.M.M. Todd, H. Bluem, V. Christina, M.D. Cole, D. Dowell, K. Jordan, J.H. Park, J. Rathke, T. Schultheiss, L.M. Young
    AES, Princeton, New Jersey, USA
  
  We describe the status of two accelerators that Advanced Energy Systems has recently designed and built, and is presently commissioning. One system will drive the THz FEL at the Fritz Haber Institute of the Max Planck Society in Berlin, while the other will produce radiation for Homeland Security applications. A key aspect of the required FEL accelerator performance is low longitudinal emittance < 50 keV-psec at 200 pC bunch charge from a thermionic electron source. The other system is compact, robust and efficient since it must be transportable.
Consultants to AES 		 
 
THP126 Obtaining Sub-Picosecond X-Ray Pulses in the Advanced Photon Source Using Laser Slicing laser, electron, photon, radiation 2357
 
  • A. Zholents, M. Borland
    ANL, Argonne, USA
  
  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). 		 
 
THP129 Emittance Reduction Approaches for NSLS-II emittance, damping, lattice, dipole 2363
 
  • W. Guo, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
NSLS-II is a third generation light source that is under construction at the Brookhaven National Laboartory. The 3GeV 792m long 30-cell storage ring will be commissioned in 2014. The emittance is lowered from 2nm to 1nm by three 7m damping wigglers. This paper will discuss the future emittance reduction approaches for NSLS-II. One option is installing more damping wigglers; an alternative solution is to manipulate the damping partition by shifting the chromatic quadrupoles horizontally. Both methods can lower the emittance effectively; however, the second method does not occupy the user straights. When the quarupoles are moved, the orbit and thus the vacuum chamber need to be redesigned, and beam dynamics could be affected. In the paper we will compare the lattice properties for the two options, and address the potential issues. 		 
 
THP136 Short Pulse Generation by Laser Slicing at NSLSII laser, photon, electron, lattice 2381
 
  • L.-H. Yu, A. Blednykh, O.V. Chubar, W. Guo, S. Krinsky, Y. Li, T.V. Shaftan, G.M. Wang, F.J. Willeke, L. Yang
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by DOE contract DE-AC02-98CH10886.
We propose an upgrade R&D project for NSLSII to generate sub-pico-second short x-ray pulses using laser slicing. In this paper we discuss the basic parameters for this system and present a specific example for a viable design and its performance. Since the installation of the laser slicing system into the storage ring will break the symmetry of the lattice, we demonstrate it is possible to recover the dynamical aperture to the original design goal of the ring. 		 
 
THP141 On the Problem of Threshold Characteristics for FELWI electron, laser, FEL, undulator 2387
 
  • K.B. Oganesyan
    YerPhI, Yerevan, Armenia
  • A.I. Artemyev, D.N. Klochkov
    GPI, Moscow, Russia
  • G. Kurizki
    Weizmann Institute of Science, Rehovot, Israel
  • Y. Rostovtsev
    University of North Texas, Denton, Texas, USA
  • M. Scully
    Texas A&M University, College Station, Texas, USA
  
  Funding: ISTC A-1602
For a free-electron laser without inversion (FELWI), es- timates of the threshold laser power are found. The large- amplification regime should be used to bring an FELWI above the threshold laser power. 		 
 
THP153 Manipulating the FEL gain process with an In-cavity Aperture System FEL, cavity, electron, laser 2405
 
  • J.Y. Li, B. Jia, S.F. Mikhailov, V. Popov, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • S. Huang
    PKU/IHIP, Beijing, People's Republic of China
  
  Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The 53.73 meters long free-electron laser (FEL) resonator at Duke University consists of two concave mirrors with the similar radius of curvature. The downstream mirror receives not only the fundamental but also higher order harmonic radiation (typically in the UV and VUV range) emitted by relativistic electrons in the magnetic field of wigglers. The power load of wiggler radiation on this mirror can thermally deform and permanently damage the multi-layer coating of the mirror, therefore, limiting the maximum power of the FEL operation and reducing the mirror lifetime. To mitigate these problems, a water-cooled aperture system has been installed inside the FEL resonator. This aperture system has been used to prevent most of off-axis helical wiggler radiation from reaching the downstream FEL mirror. It has also been used to manipulate the FEL gain process by increasing the FEL beam diffraction loss inside the resonator. In principle, this aperture system can be used as an independent FEL gain control device for FEL operation. This paper reports our preliminary study of the FEL operation using the in-cavity apertures to manipulate the FEL gain process. 		 
 
THP155 Experience of FEL Mirror Degradation at the Duke FEL and HIGS Facility FEL, cavity, radiation, laser 2408
 
  • S.F. Mikhailov, J.Y. Li, V. Popov, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  
  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. 		 
 
THP171 Demonstration of 3D Effects with High Gain and Efficiency in a UV FEL Oscillator FEL, electron, laser, simulation 2429
 
  • S.V. Benson, G.H. Biallas, K. Blackburn, J.R. Boyce, D.B. Bullard, J.L. Coleman, C. Dickover, D. Douglas, F.K. Ellingsworth, P. Evtushenko, C.W. Gould, J.G. Gubeli, D. Hardy, C. Hernandez-Garcia, K. Jordan, J.M. Klopf, J. Kortze, R.A. Legg, M. Marchlik, S.W. Moore, G. Neil, T. Powers, D.W. Sexton, M.D. Shinn, C. Tennant, R.L. Walker, A.M. Watson, G.P. Williams, F.G. Wilson, S. Zhang
    JLAB, Newport News, Virginia, USA
  
  Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150, the Air Force Office of Scientific Research, DOE Basic Energy Sciences, the Office of Naval Research, and Joint Technology Office
We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab. The high brightness of the electron beam leads to both gain and efficiency that cannot be reconciled with a one-dimensional model. Three-dimensional simulations do predict the performance with reasonable precision. Gain in excess of 100% per pass and an efficiency close to 1/2NW, where NW is the number of wiggler periods, is seen. The laser mirror tuning curves currently permit operation in the wavelength range of 438 to 362 nm. Another mirror set allows operation at longer wavelengths in the red with even higher gain and efficiency. 		 
 
THP172 Operation and Commissioning of the Jefferson Lab UV FEL using an SRF Driver ERL FEL, cavity, electron, alignment 2432
 
  • C. Tennant, S.V. Benson, G.H. Biallas, K. Blackburn, J.R. Boyce, D.B. Bullard, J.L. Coleman, C. Dickover, D. Douglas, F.K. Ellingsworth, P. Evtushenko, C.W. Gould, J.G. Gubeli, F.E. Hannon, D. Hardy, C. Hernandez-Garcia, K. Jordan, J.M. Klopf, J. Kortze, M. Marchlik, S.W. Moore, G. Neil, T. Powers, D.W. Sexton, M.D. Shinn, R.L. Walker, G.P. Williams, F.G. Wilson, S. Zhang
    JLAB, Newport News, Virginia, USA
  • R.A. Legg
    UW-Madison/SRC, Madison, Wisconsin, USA
  
  Funding: Supported by the US Dept. of Energy under DoE contract number DE-AC05-060R23177.
We describe the operation and commissioning of the Jefferson Lab UV FEL using a CW SRF ERL driver. Based on the same 135 MeV linear accelerator as the Jefferson Lab 10 kW IR Upgrade FEL, the UV driver ERL uses a bypass geometry to provide transverse phase space control, bunch length compression, and nonlinear aberration compensation necessitating a unique set of commissioning and operational procedures. Additionally, a novel technique to initiate lasing is described. To meet these constraints and accommodate a challenging installation schedule, we adopted a staged commissioning plan with alternating installation and operation periods. This report addresses these issues and presents operational results from on-going beam operations. 		 
 
THP173 Design of the SRF Driver ERL for the Jefferson Lab UV FEL FEL, linac, controls, quadrupole 2435
 
  • C. Tennant, S.V. Benson, G.H. Biallas, K. Blackburn, J.R. Boyce, D.B. Bullard, J.L. Coleman, C. Dickover, D. Douglas, F.K. Ellingsworth, P. Evtushenko, C.W. Gould, J.G. Gubeli, F.E. Hannon, D. Hardy, C. Hernandez-Garcia, K. Jordan, J.M. Klopf, J. Kortze, M. Marchlik, S.W. Moore, G. Neil, T. Powers, D.W. Sexton, M.D. Shinn, R.L. Walker, F.G. Wilson, S. Zhang
    JLAB, Newport News, Virginia, USA
  
  Funding: Support by DoE Contract DE-AC05-060R23177.
We describe the design of the SRF ERL providing the CW electron drive beam at the Jefferson Lab UV FEL. Based on the same 135 MeV linear accelerator as – and sharing portions of the recirculator with – the Jefferson Lab 10 kW IR Upgrade FEL, the UV driver ERL uses a novel bypass geometry to provide transverse phase space control, bunch length compression, and nonlinear aberration compensation (including correction of RF curvature effects) without the use of magnetic chicanes or harmonic RF. Stringent phase space requirements at the wiggler, low beam energy, high beam current, and use of a pre-existing facility and legacy hardware subject the design to numerous constraints. These are imposed not only by the need for both transverse and longitudinal phase space management, but also by the potential impact of collective phenomena (space charge, wakefields, beam break-up (BBU), and coherent synchrotron radiation (CSR)), and by interactions between the FEL and the accelerator RF system. This report addresses these issues and presents the accelerator design solution that now successfully supports FEL lasing. 		 
 
THP187 Design Concept for a Compact ERL to Drive a VUV/Soft X-Ray FEL FEL, quadrupole, linac, emittance 2468
 
  • C. Tennant, D. Douglas
    JLAB, Newport News, Virginia, USA
  
  Funding: Support by US DOE contract #DE-AC05-060R23177
We explore possible upgrades of the existing Jefferson Laboratory IR/UV FEL driver to higher electron beam energy and shorter wavelength through use of multipass recirculation to drive an amplifier FEL. The system would require beam energy at the wiggler of 600 MeV with 1 mA of average current. The system must generate a high brightness beam, configure it appropriately, and preserve beam quality through the acceleration cycle - including multiple recirculations - and appropriately manage the phase space during energy recovery. The paper will discuss preliminary design analysis of the longitudinal match, space charge effects in the linac, and recirculator design issues, including the potential for the microbunching instability. A design concept for the recirculator and a lattice solution will be presented. 		 
 
THP224 Progress Report on Development of Novel Ultrafast Mid-IR Laser System laser, FEL, coupling, electron 2543
 
  • R. Tikhoplav, A.Y. Murokh
    RadiaBeam, Santa Monica, USA
  • I. Jovanovic
    Penn State University, University Park, Pennsylvania, USA
  
  Of particular interest to X-ray FEL light source facilities is Enhanced Self-Amplified Spontaneous Emission (ESASE) technique. Such a technique requires an ultrafast (20-50 fs) high peak power, high repetition rate reliable laser systems working in the mid-IR range of spectrum (2μm or more). The approach of this proposed work is to design a novel Ultrafast Mid-IR Laser System based on optical parametric chirped-pulse amplification (OPCPA). OPCPA is a technique ideally suited for production of ultrashort laser pulses at the center wavelength of 2 μm. Some of the key features of OPCPA are the wavelength agility, broad spectral bandwidth and negligible thermal load. This paper reports on the progress of the development of the Ultrafast Mid-IR Laser System.