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MOZGBE3 Primary Study of High-Power Graphene Beam Window vacuum, proton, target, scattering 47
 
  • H. Wang, C. Meng, H. Qu, D.H. Zhu
    IHEP, Beijing, People's Republic of China
  • X. Sun, P.C. Wang
    DNSC, Dongguan, People's Republic of China
  
  Beam win­dows are usu­ally used to iso­late vac­uum or other spe­cial en­vi­ron­ments, which is a key de­vice for high-power ac­cel­er­a­tors. Graphene has ex­tremely high ther­mal con­duc­tiv­ity, high strength and high trans­parency to high en­ergy ions. It is highly suit­able for beam win­dows if the tech­nol­ogy is al­low­able. This paper will dis­cuss the pri­mary tests of graphene films, in­clud­ing vac­uum per-for­mance and ther­mal con­duc­tiv­ity per­for­mance, as well as the sim­u­lated per­for­mance of an as­sumed graphene win­dow.  
slides icon Slides MOZGBE3 [1.751 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE3  
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MOZGBE4 Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows vacuum, target, operation, site 51
 
  • C.R. Ader, M.W. McGee, L.E. Nobrega, E.A. Voirin
    Fermilab, Batavia, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.
Vac­uum thin win­dows have been used in Fer­mi­lab's ac­cel­er­a­tors for decades and typ­i­cally have been over­looked in terms of their crit­i­cal­ity and fragility. Vac­uum win­dows allow beam to pass through while cre­at­ing a bound­ary be­tween vac­uum and air or high vac­uum and low vac­uum areas. The de­sign of vac­uum win­dows, in­clud­ing ti­ta­nium and beryl­lium win­dows, will be dis­cussed as well as fab­ri­ca­tion, test­ing, and op­er­a­tional con­cerns. Fail­ure of win­dows will be re­viewed as well as safety ap­proaches to mit­i­gat­ing fail­ures and ex­tend­ing the life­times of vac­uum win­dows. Var­i­ous meth­ods of cal­cu­lat­ing the strengths of vac­uum win­dows will be ex­plored, in­clud­ing FEA. 		 
slides icon Slides MOZGBE4 [2.155 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE4  
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MOPMF062 Upgrade of the Dilution System for HL-LHC kicker, operation, damping, simulation 261
 
  • C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, T. Kramer, A. Lechner, N. Magnin, A. Perillo-Marcone, T. Polzin, E. Renner, V. Senaj
    CERN, Geneva, Switzerland
  
  The LHC Beam Dump Sys­tem is one of the most crit­i­cal sys­tems for re­li­able and safe op­er­a­tion of the LHC. A ded­i­cated di­lu­tion sys­tem is re­quired to sweep the beam over the front face of the graphite dump core in order to re­duce the de­posited en­ergy den­sity. The High Lu­mi­nos­ity Large Hadron Col­lider (HL-LHC) pro­ject fore­sees to in­crease the total beam in­ten­sity in the ring by nearly a fac­tor of two, re­sult­ing in a cor­re­spond­ingly higher en­ergy de­po­si­tion in the dump core. In this paper, the beam sweep pat­tern and en­ergy de­po­si­tion for the case of nor­mal di­lu­tion as well as for the rel­e­vant fail­ure cases are pre­sented. The im­pli­ca­tions as well as pos­si­ble mit­i­ga­tions and up­grade mea­sures for the di­lu­tion sys­tem, such as de­creas­ing the pulse-gen­er­a­tor volt­age, adding two ad­di­tional kick­ers, and im­ple­ment­ing a re­trig­ger sys­tem, are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF062  
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TUPAL022 Low-Reflection RF Window for ACS Cavity in J-PARC Linac cavity, linac, proton, impedance 1051
 
  • J. Tamura, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Ao
    FRIB, East Lansing, USA
  • F. Naito, M. Otani
    KEK, Tokai, Ibaraki, Japan
  • Y. Nemoto
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
  
  In the Japan Pro­ton Ac­cel­er­a­tor Re­search Com­plex (J-PARC) linac, the An­nu­lar-ring Cou­pled Struc­ture (ACS) cav­i­ties have been sta­bly op­er­at­ing. To main­tain this op­er­a­tion avail­abil­ity, we man­u­fac­tured three back­ups of the pill­box-type RF win­dows for the ACS cav­i­ties in fis­cal year 2015 and 2017. It is de­sir­able to min­i­mize the RF re­flec­tion of the RF win­dow to pre­vent stand­ing waves from ex­cit­ing be­tween the cav­ity and the RF win­dow, and not to sig­nif­i­cantly change the op­ti­mized cou­pling fac­tor be­tween the cav­ity and the wave­guide. To re­al­ize the min­i­miza­tion, the rel­a­tive per­mit­tiv­i­ties of the ce­ramic disks of the RF win­dows were eval­u­ated by mea­sur­ing the res­o­nant fre­quen­cies of the pill­box cav­ity con­tain­ing the ce­ramic disk. On the basis of the eval­u­ated rel­a­tive per­mit­tiv­i­ties, the pill­box-part lengths of the RF win­dows were de­ter­mined. The mea­sured Volt­age Stand­ing Wave Ra­tios (VSWRs) of the man­u­fac­tured RF win­dows are just about 1.08 and these are ap­plic­a­ble for the prac­ti­cal use.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL022  
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TUPAL050 Progress Work on a CW Deuteron RFQ with Magnetic Coupling Windows rfq, cavity, experiment, coupling 1123
 
  • Q. Fu, M.J. Easton, P.P. Gan, S.L. Gao, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang, K. Zhu
    PKU, Beijing, People's Republic of China
  • W.P. Dou, Y. He
    IMP/CAS, Lanzhou, People's Republic of China
  
  Funding: This work was supported by the National Basic Research Program of China (Grant No. 2014CB845503).
A new 162.5 MHz RFQ has been built for a joint 973 pro­ject be­tween Peking Uni­ver­sity (PKU) and In­sti­tute of Mod­ern Physics (IMP). It is de­signed to de­liver 50-mA deuteron beams to 1 MeV in CW mode, with an in­ter-volt­age of 60 kV and a length of 1.809 m. Due to its win­dow-type struc­ture, the RFQ has com­pact cross-sec­tion, suf­fi­cient mode sep­a­ra­tion and high spe­cific shunt im­ped­ance. It con­sists of two seg­ments fab­ri­cated and in­stalled at IMP. The as­sem­bling error of the cav­ity is less than 0.05 mm. The RF mea­sure­ments show good elec­tri­cal prop­er­ties of the res­o­nant cav­ity with a mea­sured un­loaded qual­ity fac­tor equal to 96.4% of the sim­u­lated value. After tun­ing, we ob­tained the nom­i­nal fre­quency and field un­bal­ance within 1.0%. Prepa­ra­tion of high-power test of this RFQ is un­der­way. This paper will cover the fab­ri­ca­tion de­tails and RF mea­sure­ments, as well as the progress of high-power test. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL050  
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