MOZBA —  Monday Parallel Session 3   (02-Sep-19   14:00—16:00)
Chair: P. Musumeci, UCLA, Los Angeles, California, USA
Paper Title Page
MOZBA1 LCLS-II SC Linac: Challenges and Status -1
  • M.C. Ross
    SLAC, Menlo Park, California, USA
  Funding: ∗ This work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515
The Linac Coherent Light Source II (LCLS-II) project requires the assembly, test, and installation of 37 cry-omodules (CM) in order to deliver a 4 GeV CW electron beam to the FEL undulators for production of both hard and soft X-ray pulses at a repetition rate of up to 1 MHz. All of the cryomodules will operation in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. The assembly and testing of the 1.3 GHz cry-omodules is nearing completion and the 3.9 GHz cry-omodules work is entering to assembly and testing phase. Roughly 60% of the cryomodules have been shipped to SLAC for installation in the accelerator enclosure. The status and challenges of these efforts will be reported in this paper.
slides icon Slides MOZBA1 [80.486 MB]  
MOZBA2 Operational Experience with Superconducting Undulators at APS -1
  • K.C. Harkay, L.E. Boon, M. Borland, J.C. Dooling, L. Emery, V. Sajaev, Y.P. Sun
    ANL, Lemont, Illinois, USA
  Funding: Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
APS has been developing superconducting undulators for over a decade. Presently, two planar and one helical device are in operation in the APS storage ring, and a number of devices will be installed in the APS Upgrade ring. All superconducting devices perform with very high reliability and have very minor effect on the storage ring operation. To achieve this, a number of storage ring modifications had to be done, such as introduction of the beam abort system to eliminate device quenches during beam dumps, and lattice and orbit modifications to allow for installation of the small horizontal aperture helical device with magnet coils in the plane of synchrotron radiation.
slides icon Slides MOZBA2 [3.640 MB]  
MOZBA3 Strongly Tapered Helical Undulator System for TESSA-266 -1
TUPLH14   use link to see paper's listing under its alternate paper code  
  • T.J. Campese, R.B. Agustsson, I.I. Gadjev, A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • W. Berg, A. Zholents
    ANL, Lemont, Illinois, USA
  • P.E. Denham, P. Musumeci, Y. Park
    UCLA, Los Angeles, USA
  Funding: DOE SBIR Award No. DE-SC0017102
RadiaBeam, in collaboration with UCLA and Argonne National Laboratory (ANL), is developing a strongly tapered helical undulator system for the Tapering Enhanced Stimulated Superradiant Amplification experiment at 266 nm (TESSA-266). The experiment will be carried out at the APS LEA facility at ANL and aims at the demonstration of very high energy conversion efficiency in the UV. The undulator system was designed by UCLA, engineered by RadiaBeam, and is presently in fabrication at RadiaBeam. The design is based on a permanent magnet Halbach scheme and includes a short 30 cm long buncher section and four 1 m long undulator sections. The undulator period is fixed at 32 mm and the magnetic field amplitude can be tapered by tuning the gap along the interaction. Each magnet can be individually adjusted by 1.03 mm, offering up to 25% magnetic field tunability with a minimum gap of 5.58 mm. A custom designed 316L stainless steel beampipe runs through the center with a clear aperture of 4.5 mm. This paper discusses the design and engineering of the undulator system, fabrication status, and plans for magnetic measurements, and tuning.
slides icon Slides MOZBA3 [9.166 MB]  
MOZBA4 Recent Developments in High Power High Brightness Double Bunch Self-Seeding at LCLS-II -1
TUPLH12   use link to see paper's listing under its alternate paper code  
  • A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.A. Lutman, G. Marcus, C. Pellegrini
    SLAC, Menlo Park, California, USA
  We discuss the power and spectral characteristics of an X-ray FEL, LCLS-II, operating in a double bunch self-seeding scheme (DBFEL). We show that it can reach very high power levels in the photon energy range of 4-8 keV. We discuss the system implementation on LCLS-II, including the design of a four-bounce crystal monochromator, and linac wakefields effects. Finally, we offer multiple applications of the DBFEL for high-field QED, AMO physics and single particle imaging.  
slides icon Slides MOZBA4 [3.166 MB]  
MOZBA5 Optimized Linear and Second Order Chromaticity Setpoints for the Advanced Photon Source Upgrade -1
  • Y.P. Sun
    ANL, Lemont, Illinois, 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 nominal single particle dynamics optimizations of the Advanced Photon Source upgrade (APS-U) lattice are performed with dense numerical simulations of local momentum acceptance and dynamic acceptance. These simulations are quite time consuming, which may take weeks for optimizing one setpoint of linear chromaticity. In this paper, an alternative optimization method is adopted to generate optimized linear and second order chromaticity setpoints for the Advanced Photon Source upgrade lattice. This method is efficient in computing time needed, which is capable to generate a grid of optimized chromaticity setpoints in a relatively short time. The performance of these lattice solutions are verified by simulations with reasonable errors. These lattice solutions with different linear (or second order) chromaticity may be useful for the future APS-U commissioning and operations.
slides icon Slides MOZBA5 [3.348 MB]  
MOZBA6 The Broad-Band Impedance Budget of the Accumulator Ring in the ALS-U Project -1
MOPLM26   use link to see paper's listing under its alternate paper code  
  • D. Wang, S. De Santis, D. Li, T.H. Luo, M. Venturini
    LBNL, Berkeley, California, USA
  • K.L.F. Bane
    SLAC, Menlo Park, California, USA
  Design work is underway for the upgrade of the Advanced Light Source (ALS-U) to a diffraction-limited soft x-rays radiation source. It consists of an accumulator and a storage ring. In both rings, coupling-impedance driven instabilities need careful evaluation to ensure meeting the machine high-performance goals. This paper presents the impedance budget of the accumulator ring both longitudinally and transversely. The budget includes the resistive wall impedance as well as the geometric impedance from the main vacuum components. Our calculations primarily rely on electromagnetic simulations with the CST code; when possible validation has been sought against analytical modeling, typically in the low-frequency limit, and good agreement generally found. Collective-instability current thresholds are also discussed.  
slides icon Slides MOZBA6 [7.204 MB]  
poster icon Poster MOZBA6 [3.652 MB]