Author: Igarashi, S.
Paper Title Page
MOPAB51 Beam Dynamics Study for J-PARC Main Ring by Using the 'Pencil' and Space-charge Dominated Beam: Measurements and Simulations 157
 
  • A.Y. Molodozhentsev, S. Igarashi, Y. Sato, J. Takano
    KEK, Ibaraki, Japan
 
  J-PARC Main Ring (MR) study has been per­formed dur­ing 2013-2014 to op­ti­mize the ma­chine per­for­mance. As the re­sult of this ac­tiv­ity the ‘200 kW’ pro­ton beam has been suc­cess­fully ex­tracted from MR into the ‘Neu­trino’ beam­line. Total par­ti­cle losses, lo­cal­ized at the MR col­li­ma­tion sec­tion, have been es­ti­mated as 150 W. The 'low-losses' MR op­er­a­tion has been achieved after op­ti­miza­tion the in­jec­tion process, set­ting the MR RF sys­tem, dy­namic con­trol of the chro­matic­ity and com­pen­sa­tion the lin­ear cou­pling res­o­nance. In frame of this re­port we will dis­cuss the ob­tained ex­per­i­men­tal re­sults and com­pare it with sim­u­la­tions, per­formed ex­ten­sively for dif­fer­ent ma­chine op­er­a­tion sce­nario, in­clud­ing the 'pen­cil' low in­ten­sity beam and the space-charge dom­i­nated beam. The ob­tained re­sults demon­strate agree­ment be­tween sim­u­la­tions and mea­sure­ments for emit­tance evo­lu­tion and losses for dif­fer­ent cases. The de­vel­oped MR com­pu­ta­tional model will be used to op­ti­mize the ma­chine per­for­mance for the ‘MegaWatt’ MR op­er­a­tion sce­nario with lim­ited losses. The mod­el­ing of the beam dy­nam­ics for these cases has been per­formed by using the ‘PTC-OR­BIT’ com­bined code, in­stalled on the KEK su­per­com­puter.  
 
THO1LR02
Recent Commissioning of High-Intensity Proton Beams in J-PARC Main Ring  
 
  • Y. Sato, T. Koseki, J. Takano, S. Yamada, N. Yamamoto
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • H. Harada, M.J. Shirakata, F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • S. Igarashi
    KEK, Ibaraki, Japan
 
  In the J-PARC, the main ring (MR) pro­vides high power pro­ton beams of 240 kW (1.24·1014 pro­tons per pulse) to the neu­trino ex­per­i­ment. The linac en­ergy was up­graded from 181 MeV to 400 MeV in 2013, and its cur­rent is going to be from 30 mA to 50 mA in 2014. If the beam losses are min­i­mized and lo­cal­ized in the MR, the MR will have the ca­pa­bil­ity to pro­vide over 300 kW after the up­stream up­grades. Based on the up­grades and im­prove­ments of the 3-50BT and the MR in 2013 and 2014, fol­low­ing ap­proaches have been tested and com­mis­sioned: 2nd har­monic RFs under the faster rise-up time im­prove­ment of the in­jec­tion kick­ers, to in­crease bunch­ing fac­tor; in­tra-bunch feed-back sys­tem and chro­matic­ity pat­terned cor­rec­tion, to sup­press in­sta­bil­ity; in­tra-bunch feed-back, tail and re­flec­tion im­prove­ment of the in­jec­tion kick­ers, and 6D match­ing be­tween the 3-50BT and the MR, to re­duce in­jec­tion losses; achro­matic tun­ing at the col­li­ma­tor sec­tion of the 3-50BT to cut beam halo ef­fec­tively; col­li­ma­tor up­grades, aper­ture en­large­ment at dis­per­sion peaks, and mo­men­tum spread con­trol, to lo­cal­ize beam losses in the col­li­ma­tor sec­tion; new op­er­a­tion point sur­vey.  
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