Author: Aleksandrov, A.V.
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MOOCB2 Laser System Design and Operation for SNS H− Beam Laser Stripping 57
 
  • Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A.A. Menshov, A. Webster
    ORNL, Oak Ridge, Tennessee, USA
  • A. Rakhman
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: This work has been partially supported by U.S. DOE grant DE-FG02-13ER41967. ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Recently, a high-efficiency laser assisted hydrogen ion (H−) beam stripping was successfully carried out in the Spallation Neutron Source (SNS) accelerator. The experiment was not only an important step toward foil-less H− stripping for charge exchange injection, it also served as a first example of using megawatt ultraviolet (UV) laser in an operational high power proton accelerator facility. This talk reports the design, implementation, and commissioning results of the macropulse laser system, laser transport line, and laser operation for the laser stripping experiment. The macropulse laser consists of a mode-locked picosecond pulsed seed laser and a burst-mode Nd:YAG laser amplifier. The general design concept can be adapted to any temporal beam structures in most accelerators. We have achieved UV pulses with the pulse widths varying between 34 to 54 ps and a maximum peak power over 3.5 MW. A laser transport line is installed to deliver the UV beam to the laser stripping chamber at a transmission efficiency of 70%. Laser operation including remote control and monitor of laser parameters will be described. 		 
slides icon Slides MOOCB2 [11.306 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOOCB2  
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MOPIK118 Model Based Optics Studies in the MEBT Section of SNS 814
 
  • A.P. Shishlo, A.V. Aleksandrov, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
  
  Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy.
The paper presents the beam dynamics studies for the Medium Energy Beam Transport (MEBT) section of the Spallation Neutron Source (SNS) accelerator. The analysis of measurements is based on the PyORBIT linac model. The diagnostics data includes wire scanners' profiles, slit-harp and slit-slit transverse emittances, MEBT re-bunchers calibration data, and bunch length measurements. The MEBT is a matching section between RFQ and a Drift Tube Linac (DTL). It is also a place for beam halo scraping which helps to reduce beam loss in downstream linac sections. The linac simulation code was benchmarked against the diagnostics data. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK118  
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TUPVA145 Commissioning of the New SNS RFQ and 2.5MeV Beam Test Facility 2438
 
  • A.V. Aleksandrov, S.M. Cousineau, M.T. Crofford, B. Han, Y.W. Kang, A.A. Menshov, A. Webster, R.F. Welton, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  • B.L. Cathey, C.C. Peters
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
SNS injector uses a four-vane 402.5MHz RFQ for accelerating the H− beam with 38mA peak current and 7% duty factor to 2.5MeV. The original RFQ, commissioned in 2002, has been able to support SNS operation up to the design average beam power of 1.4MW. However, several problems have developed over almost fifteen years of operation. A new RFQ with design changes addressing the known problems has been built and commissioned up to the design beam power at the new SNS Beam Test Facility (BTF). The BTF consists of a 65 keV H− ion source, a 2.5MeV RFQ, a beam line with advanced transverse and longitudinal beam diagnostics and a 6 kW beam dump. This presentation provides results of the RFQ commissioning and the BTF beam instrumentation commissioning. We also discuss progress of the ongoing multidimensional phase space characterization experiment and future beam dynamics study planned at the SNS BTF. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA145  
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TUPVA146 6D Phase Space Measurement of Low Energy, High Intensity Hadron Beam 2441
 
  • B.L. Cathey
    ORNL RAD, Oak Ridge, Tennessee, USA
  • A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The work has been partially supported by NSF grant 1535312
The goal of this experiment is to measure the full 6D phase space of a low energy, high intensity hadron beam. We use 4D emittance measurement techniques for the transverse plane combined with dispersion measurement and a beam shape monitor to provide the longitudinal phase space. The Beam Testing Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate front end of the SNS accelerator is being used to facilitate the measurement. Early 6D measurements will be presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA146  
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TUPVA148 FODO Lattice Design for Beam Halo Research at SNS 2449
 
  • Z.L. Zhang
    ORNL RAD, Oak Ridge, Tennessee, USA
  • A.V. Aleksandrov, S.M. Cousineau
    ORNL, Oak Ridge, Tennessee, USA
  
  Beam halo is a big challenge for high intensity accelerators. Knowledge of the mechanisms of halo formation could help to prevent it. The Spallation Neutron Source (SNS) Beam Test Facility (BTF) is a functional duplicate of the SNS front end with enhanced diagnostics capable of accelerating 50 mA H− or protons to 2.5 MeV. To explore halo development in both matched and mismatched beams, a dedicated FODO lattice is being designed as an extension to the BTF. The FODO lattice will be 3.5 meters in length and is comprised of 16 quadrupole magnets, with dedicating matching magnets. Simulations of the design lattice show halo can be seen clearly in the phase space density plot when beam is mismatched. Details of the FODO design will be presented in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA148  
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