REMARKABLE PRESSURE RISE AT PUMPING PORT IN J-PARC MAIN RING Masahiko Uota # , Masayuki Shimamoto, Yoshihiro Sato, Yasuhiro Takeda, Yoichiro Hori, Yoshio Saito KEK 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan Abstract In J-PARC MR synchrotron with high power beam operation, the remarkable and endless pressure-rise over 10 -4 Pa or more is found when a ion-pump of the ring turns off by accident or on purpose. This high pressure exceeds the normal pressure distribution of pump series and causes the beam loss by nuclear interaction. The outgassing rate depends on the existence of external magnet field at the pumping port, the initial pressure and the operating beam power. A minus potential synchronized with the operating cycle are found at the electrode in pumping port. The formation of electron cloud is considered to the pressure rise. J-PARC MR イオンポンプ OFF 時の顕著な圧力上昇 1. J-PARC 50GeV 8Q6P@PQ (MR) !ウァア ćチWヲ,ホkォツČヨí・エ )+ör+hùñLRA!ä+óxッ 3.04 ヤ 30GeV 92×10 12 a (145kW マ) ĂFRK /`゚,&çč MR !Čミラン !JQHツ, 1600m ýARB?N Q7ヌ,č MR ミラJQH! 0.5—0.6 m 3 /s :E>;14QJQH (IP) 'Č in-vacuum ケ z/gnċc/áà,ehケz=3 QDR/āûi!Čミラ~m!JQ H/レ,p゙。ナâi/,č& Čùñォ!ČFRKwッ~mTィ fx.+ëソ-, [1,2] č 2010 1 ョČj(hm 35kW 0IR@<QH #、iÿ÷àìĊùñ/êォČシ0R6 û!、l~mTィヒ&ČーõĆ IP #111 \ò*'é02@5:j(ë ソ-(} 1 )č&Čw 5 ョČ 60kW ÷àùñ dサッÿWČ0R6û IP 2 tĆタ「ą JQHüåャ)+\ò~m 6×10 -7 Pa * ċb 1.2×10 -6 Pa #ユêč&&セ ùñ/þ,Čùñwットフヘ~m Tィ/þČø! 10 -3 Pa /ïスヒ5:マ [_ハ),ZコワTィ/FRKP:LC; カム MPS フČùñhm/U,/ ,Yîフノ(} 1 u)č õĆ]サヌ IP ãJQH JR@,q{VゥČXッフ」ヘ~mT ィ!Čイ*,oĄyĉ,sæ ,čČ~mTィニ/フ」ヘ 02@5:q{/,(Č÷àùñW NQ7fx IP /Ď 2 tùñ ą ロ|メォÿ「dサ~mTィク/ë ソč&ČďJQHJR@オルgJQH &ôWG>60>HĆキ/åČJQHJR @gĆ^/ùñWソč 2. 2011 ェォツ MR IP üå/} 2 モč MR 0R6û! 1 module 15 50.8m 24 module *,č 2010 &!Č IP üå、! 1.5 t /module Č$% 34m リÿăüå! module xッČ"!FRKðúxッ!Sè čJQHツ,ýE1H~m !ČJQH/レČWÿツ/ュ,。ナâi/ č IP 、L9MRO、v.テČL 9MROWČðú dispersion Ā、ュ 3-50BT RCS Abort Dump WALL Slow Extraction Neutrino Beam Line RF RF KM1 KM2,3 KM4,5 SM31~34 0 25 50 100m ESS2 SMS3 SMS2 SMS1 ESS1 InjK COL1 COL2 COL3 ABS InjSM1,2 GV GV GV GV GV GV GV GV GV GV(A) GV2 GV(HD) GV(N) GV GV GV GV GV GV GV GV GV GV1 GV3 GV4 IP2 IP3 IG4 CG4 RP3 @MW IG3 CG3 RP2 @MW IP1 IG1 CG1 IG2 CG2 RP1 IG5 IP4 IG6(NC) PLUG1 IG8 CG6 RP6 IG7 CG5 @MW IG9 IP11 IG10 CG7 RP7 @MRPM RP CG,RP IP13 IP12 RP IP,IG013 IP,RP,IG015 RP RP IG005,CG,RP IG006 CG,RP IG004@MRPM IP,IG008 IP,IG012 IP,IG011_1 IP IP IP IP IP14 IP5 IP6 IP7 IP8 IP10 IP107 IP097 IP093 IP087_1 IP_SLOWEXT IP085 IP IP IP IP IP IP IP IP IP IP IP IP111 IP116 IP121 IP125 IP130 IP135 IP139 IP144 IP146 IP148 IP IP IP IP IP IP IP IP IP IP IP150_1 IP IP159 IP165 IP169 IP174 IP179 IP183 IP188 IP193 IP197 IP202 IP207 IP211 IP216 IP102 IP021 IP025 IP028 IP042 IP056 IP IP100 IP114 IP128 IP142 IP172 IP186 IP200 IP214 IP030 IP035 IP039 IP044 IP049 IP053 IP058 IP IP IP IP074 IPが粗 : 最近接IPまで34m IPが密 : 最近接IPまで15~18m Arc A Arc B Arc C Insertion A Insertion C Insertion B 粗 密 粗 密 粗 密 粗 2011/1 IP入口にシールド (パンチングメタル) 密 2011/1 ループアンテナ 2011/1 円盤電極 A B B Aʼ A Aʼ } 2: MR JQHüå}(2011 3 ョネ). 10 -7 10 -6 10 -5 10 -4 10 -3 Pressure [Pa] 16:15 05/11/10 16:30 16:45 17:00 17:15 17:30 17:45 18:00 dat 60 40 20 beam power [kW] IG_028p IG_042p IG_049p MRPWRv IP039&044 off by controller down Beam off by MPS(BLM) ~1e-6 Pa in continuous operation exponentially (or more) rise cont. op. resume } 1: OFF-IP ),ùñォ~mTィ(2010 jĈ). ____________________________________________ # [email protected] Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan) - 1383 -