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beam-transport

Paper Title Other Keywords Page
TUP026 Low and Medium Energy Beam Trasport Upgrade at BNL 200 MeV Linac linac, polarization, solenoid, ion 455
 
  • D. Raparia, J.G. Alessi, B. Briscoe, J.M. Fite, O. Gould, V. LoDestro, M. Okamura, J. Ritter, A. Zelenski
    BNL, Upton, Long Island, New York
 
 

BNL 200 MeV linac has been under operation since 1970 and gone through several changes during its 40 year lifetime. The latest reconfiguration in low and medium energy (35 and 750 keV) beam transport lines results in about a factor of 2 reduction in the transverse emittance for the accelerated polarized proton beam, and for the unpolarized high current H- beam a several fold reduction in the radiation levels due to beam losses throughout the linac and isotope production facility complex with more beam current on the isotope production target. These improvements are achieved by proper matching into the linac in longitudinal as well as transverse phase space. This paper will emphasize how longitudinal matching resulted in lower emittance and beam losses.

 
TUP067 Reduction of Transverse Emittance Growth in J-PARC DTL emittance, DTL, linac, quadrupole 563
 
  • H. Sako, M. Ikegami, A. Miura, G.H. Wei
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
 

Transverse emittance growth was observed in J-PARC Drift Tube Linac (DTL). In order to suppress the growth, we searched for optimum parameters at MEBT1, by measuring transverse emittance using four wire scanner monitors at the exit of DTL. At 15 mA peak beam current in Dec 2009, horizontal and vertical rms emittance was reduced by 12 % and 10 %, respectively, by setting the amplitudes of the first and second bunchers to 120 % and 90 % with respect to the designed settings. The resulting normalized horizontal and vertical emittance was 0.230 and 0.205 pi mm mrad. At 20 mA in Jan 2010, horizontal and vertical rms emittance was reduced by 17 % and 10 %, respectively, by setting the amplitudes of the first and second bunchers to 110 % and 80 % with respect to the designed settings. The resulting normalized horizontal and vertical emittance was 0.273 and 0.253 pi mm mrad. At 15 mA, we further reduced the horizontal and vertical emittance to 0.171 and 0.200 pi mm mrad by increasing the eighth quadruple magnet field at MEBT1 by 20 % to the designed value. The measured transverse emittance dependence on buncher electric field and quadruple magnetic field will be compared with simulation.

 
THP086 Beam Transport in a Proton Dielectric Wall Accelerator* proton, focusing, quadrupole, emittance 941
 
  • Y.-J. Chen, D.T. Blackfield, G.J. Caporaso, S.A. Hawkins, S.D. Nelson, B. R. Poole
    LLNL, Livermore, California
 
 

Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory [1]. The DWA accelerator's beam tube is a stack of high gradient insulators, consisting of alternating layers of insulators and conductors. Characteristically, insulators' surface breakdown thresholds go up as the applied voltages' pulse width goes down. To attain the highest accelerating gradient in the DWA accelerator, the accelerating voltage pulses should have the shortest possible duration. This can be done by appropriately timing the switches in the transmission lines, which feed the continuous HGI tube. The accelerating voltage pulses arrive at the accelerator axis along the beam tube at different times so as to appear to the charged particle bunch as a traveling accelerating voltage wave. We have studied the beam transport in a baseline DWA configuration by performing PIC simulations using the 3-D, EM PIC code, LSP [2]. Sensitivity of the output beam parameters to the switch timing will be presented. In addition to the baseline configuration, various alternative focusing schemes will be discussed.


[1] G. J. Caporaso, Y-J Chen and S. E. Sampayan, "The Dielectric Wall Accelerator", Rev. of Accel. Sci. and Tech., vol. 2, p. 253 (2009).
[2] Alliant Techsystems Inc., http://www.lspsuite.com/.