TUP2WA —  WG-A   (19-Jun-18   16:00—18:00)
Chair: V.A. Lebedev, Fermilab, Batavia, Illinois, USA
Paper Title Page
TUP2WA01 Optical Stochastic Cooling Experiment at the Fermilab IOTA Ring -1
  • J.D. Jarvis, V.A. Lebedev, H. Piekarz, P. Piot, A.L. Romanov, J. Ruan
    Fermilab, Batavia, Illinois, USA
  • M.B. Andorf, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  Funding: Fermi National Accelerator Laboratory is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Beam cooling enables an increase of peak and average luminosities and significantly expands the discovery potential of colliders; therefore it is an indispensable component of any modern design. Optical Stochastic Cooling (OSC) is a high-bandwidth, beam-cooling technique that will advance the present state-of-the-art, stochastic cooling rate by more than three orders of magnitude. It is an enabling technology for next-generation, discovery-science machines at the energy and intensity frontiers including hadron and electron-ion colliders. This paper presents the status of our experimental effort to demonstrate OSC at the Integrable Optics Test Accelerator (IOTA) ring, a testbed for advanced beam-physics concepts and technologies that is currently being commissioned at Fermilab. Our recent efforts are centered on the development of an integrated design that is prepared for final engineering and fabrication. The paper also presents a comparison of theoretical calculations and numerical simulations of the pickup-undulator radiation and its interaction with electrons in the kicker-undulator.
slides icon Slides TUP2WA01 [20.009 MB]  
TUP2WA02 Momentum Slip-Stacking Simulations for CERN SPS Ion Beams with Collective Effects -1
  • D. Quartullo, T. Argyropoulos, A. Lasheen
    CERN, Geneva, Switzerland
  The LHC Injectors Upgrade (LIU) Project at CERN aims at doubling the total intensity of the Pb-ion beam for the High-Luminosity LHC (HL-LHC) project. This goal can be achieved by using momentum slip-stacking (MSS) in the SPS, the LHC injector. This RF gymnastics, originally proposed to increase bunch intensity, will be used on the intermediate energy plateau to interleave two batches, reducing the bunch spacing from 100 to 50 ns. The MSS feasibility can be tested only in 2021, after the beam controls upgrade of the SPS 200 MHz RF system, so beam dynamics simulations are used to design this complicated beam manipulation. Simulations of the MSS were performed using the CERN BLonD code with a full SPS impedance model. Attention has been paid to the choice of the RF and machine parameters (beam energy, time duration, RF frequency and voltage programmes) to reduce losses and the final bunch length which is crucial for the injection into the LHC 400 MHz buckets. The initial beam parameters used in simulations were obtained from beam measurements in the first part of the SPS cycle taking into account bunch-by-bunch losses on flat bottom and development of bunch instabilities.  
slides icon Slides TUP2WA02 [8.272 MB]  
TUP2WA03 Studies of Capture and Flat-Bottom Losses in the SPS -1
  • M. Schwarz, H. Bartosik, E. Chapochnikova, A. Lasheen, J. Repond, H. Timko
    CERN, Geneva, Switzerland
  One of the strong limitations for reaching higher beam intensities in the SPS, the injector of the LHC at CERN, are particle losses at flat bottom that increase with beam intensity. In this paper, different sources of these losses are investigated for two available SPS optics, using both measurements and simulations. Part of the losses originate from the PS-to-SPS bunch-to-bucket transfer, because the PS bunches are rotated in longitudinal phase space before injection and do not completely fit into the SPS RF bucket. The injection losses due to different injected bunch distributions were analyzed. Furthermore, at high intensities the transient beam loading in the SPS has a strong impact, which is (partially) compensated by the LLRF system. The effect of the present and future upgraded one-turn delay feedback system and phase loop on flat-bottom losses was studied using the longitudinal tracking code BLonD. Finally, the total particle losses are also affected by limitations in the SPS momentum aperture, visible for higher RF capture voltages in optics with lower transition energy and higher dispersion.  
slides icon Slides TUP2WA03 [8.038 MB]  
TUP2WA04 Dynamic Vacuum Simulation for the BRing -1
  • P. Li, Z. Dong, M. Li, J.C. Yang
    IMP/CAS, Lanzhou, People's Republic of China
  • L.H.J. Bozyk
    GSI, Darmstadt, Germany
  Funding: Youth Innovation Promotion Association of Chinese Academy of Sciences 2016364, National Natural Science Foundation of China (Project No. 11675235).
Large dynamic vacuum pressure rises of orders of magnitude which caused by the lost heavy ions can seriously limit the ion intensity and beam lifetime of the heavy ion accelerator, especially for the machine that operate the intermediate charge state heavy ion. The High Intensity heavy ion Accelerator Facility (HIAF) which will be built by the IMP will accumulate the intermediate charge state ion 238U35+ to intensity 2*1011 ppp to different terminals. In order to control the dynamic vacuum effects induced by the lose beams and design the collimation system for the BRing of the HIAF, a newly developed simulation program (ColBeam) and GSI's simulation code StrahlSim are both conducted and the dynamic vacuum simulation result is calculated by the StrahlSim. According to the simulation result, 3*1011 ppp particles is the up limit beam intensity can be extracted for the current BRing vacuum system design. Higher beam intensity can be reach to 5*1011 ppp when the NEG coating technology must be implemented for the dipole and quadrupole chamber.
HIAF, Collimation, Dynamic vacuum
slides icon Slides TUP2WA04 [9.947 MB]  
TUP2WA05 Effect of the Extraction Kickers on the Beam Stability in the CERN SPS -1
  • A. Farricker, M.S. Beck, J. Repond, C. Vollinger
    CERN, Geneva, Switzerland
  Longitudinal beam instability in the CERN SPS is a major limitation in the ability to achieve the bunch intensities required for the goals of the High-Luminosity LHC project (HL-LHC). One of the major drivers in limiting the intensity of the machine is the broadband contribution to the beam-coupling impedance due to the kicker magnets. The extraction kickers (MKE) discussed in this paper are known to give a significant contribution to the overall longitudinal beam-coupling impedance. We present the results of bench measurements of the MKE's impedance to determine the accuracy of electromagnetic simulation models from which the impedance modelused for beam dynamics simulationsis constructed. In addition, we discuss the feasibility and implementation of beam measurements that can indicate the contribution of the MKE magnets to the longitudinal beam-coupling impedance of the SPS.  
slides icon Slides TUP2WA05 [2.698 MB]  
Beam Dynamics Study of the Heavy Ion Bunch Rotation With Space Charge Effect in BRing at HIAF  
  • D.Y. Yin
    IMP/CAS, Lanzhou, People's Republic of China
  BRing-the key part of the High Intensity heavy-ion Accelerator Facility(HIAF) complex will provide intense heavy ion beams to expand nuclear and related researches into presently unreachable region. As a synchrotron, BRing is designed to accumulate and accelerate heavy ion beams provided by iLinac up to high intensity and energy. Compared to the present research facility CSRm of HIRFL, the primary heavy ion beams intensity will be increased substantially which will open a new path for the HED physics research which requires high quality, well focused, and strongly bunched intense particle beams to satisfy the very high energy deposition to achieve high target power density in laboratory. Based on the beam parameters of 238U35+ proposed by the BRing at HIAF, the two critical issues will be studied. One is transmission efficiency during the whole process which can be a necessary prerequisite to ensure the beam intensity, and the other one is bunch rotation longitudinally which is an effective way of producing short pulse duration bunch. Through the analytical calculations and tracking simulations, the possible bunch length and peak beam power after rotation are presented.  
slides icon Slides TUP2WA06 [2.341 MB]