Impedance Issues in SuperKEKB
D. ZhouWith contributions from
KEK: T. Abe, T. Ishibashi, Y. Morita, K. Shibata, Y. Suetsugu,
M. Tobiyama, M. Yoshida, ...
SLAC: Y. Cai, G. Stupakov
The 19th KEKB Accelerator Review Committee, Mar. 03, 2014

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1. Introduction: Machine parameters     3

1. Introduction: Tasks on impedance issues%#!
5 !-(#,,  #!"%,,...
5 !%/ '%#-+)42.3

#5!!" !
'5#"!"&%%"!

 /%#&"!
5"%-%","#/'
!" #, 5 !& !-#", 0((/ #1 %#/%#&"!
5 %#/%" !& !!""(0(%" !!#&'14

2. Impedance calculations: Modeling !$&)',%

 !$&(',%

 #

 #

 $ %5 "  " 

2. Impedance calculations: Modeling: LER 

#!     !

6 " "  

2. Impedance calculations: Modeling: LER   

HorizontalVertical  7       

2. Impedance calculations: Modeling: HER"#"# 8!  !  ! 

2. Impedance calculations: Modeling: HER 

 9      

2. Impedance calculations: Results: LER!,# !
2(&1/+02!    !2   -   .*# !  2%* " ")$)"! ) 10

2. Impedance calculations: Results: LER

 "  +&$*)
+   ( '!" '  !#'
"' +        

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2. Impedance calculations: Results: HER"-$" 3)'20,13 +$"
3 .  /&3&+##* *%

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2. Impedance calculations: Results: HER "  

*%#)(*  '!  & !" &  &"&  !&   !& * "   13

3. Loss factors and HOM power: LER "!,+ #- #&*( %-  #&)(((14$ 

3. Loss factors and HOM power: HER! ,*"- "%)( $- "%+((15 # 

4. Single-bunch effects: Longitudinal: LER &$"(# &# "&0!(:"0!/" "'!
:#!"! !##"&!"&#: &#,*95.71"&&!!#: &# #!""!& #846.43
:  !)## !##....

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4. Single-bunch effects: Longitudinal: LER #!% #  #+%)2 (#+% (   *01 $*2  !+% !01 #! 01 # & $# 

 0/*,.-,17

4. Single-bunch effects: Longitudinal: HER'% #)$!'$  #' 1").
<#1" 0# # ("< (#.  1$*! '#9; !" (<'$-+:6/82#''""$<'$ $"# #" ' $957/54
<  "*$  $! "$$/18

4. Single-bunch effects: Longitudinal: HER #!% #  #+%)4 (#+% (   *23 $*4  !+% !23 #! 23 # & $#  21*0/.-

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4. Single-bunch effects: Longitudinal: CSR
 ( )$  "  '3  $*  3 "  # (((3   2/
4/3

CIA αp γσδ2 σz
Nth =ξth1/3ceσz Rme c
IA = 4π0e3

χ = σzRb3

'    'ξth = 0.5 + 0.34χ

 "  'a 1
ξ = ξth (χ, A = ,)b ω s τd20

( ( & *.1&-/-1-/+/-.0,

4. Single-bunch effects: Longitudinal: CSR
 & '"      %0 !  χ            21 



 



& & $ (,/$+-+/+-)-+,.*

4. Single-bunch effects: Longitudinal: CSR)  "  '4"$ 4'3..&3-2& 3.(1/.4""'-,)/4 #""'0) $"

 22 ( 

4. Single-bunch effects: Longitudinal: CSR ,  #  )7  #!,  7##$ /.,2) 
7 #! 
###(%5/*1#)/)0)1)4


'6,.*./3 +
(%5.*3

'6,.*2 +23#)/)0)4) 

4. Single-bunch effects: Transverse: Beam tilt#$   ".      .  %  &12βΔy =θyrms
24 sin (πνy )N e2
θrms =γm0 c2
Wy  = ∞−∞(Wy − Wy )2 

Wy (s)λ(s)ds-(#*+ -(#+ -) !-,24#

4. Single-bunch effects: Transverse: Beam tilt
,   !-$ !  +; $6  0 1" ;35 4  # +9/5.5*'$9437,8
; :3,5 )Vertical
12βΔy =θyrms
24 sin (πνy )N e2 Δyθrms =γm0 c2

(Wy −Wy )2(%9825

4. Single-bunch effects: TMCI: LER   !"#$26

    

5. Summary!'% #>!'% #)$.,;9;= ##$ "#! )"#%% > $'!'% #)$.,;708;=#' 1");='% #  >"#("#!'% #)$.,;708;=$ ''$  "'"$"#$$++## $'#1'$#>.,<80:4#''""$ " $ 
>"#$  "> $"# /  "2("+3"'#'% #"#("##1'$#>%$'$ $"#("#!*> '$  $ "#"#$  "27

6. Future plan !$( 1#*(& 8 $#!$ (#$8 !%!(& $*#*#$$
8 (1$!(& $8 # !# $  . . / %1#*(& (#$(& $8#($(& $ )$ )$ )#2#+%#+
#"($% !(&! *#.$!+*% -38 #$(& $ &% 8!% $1(%$ ( $%+!# #  #& $80/ ..00080 %(! )/!(& $.$%&$.000

 #!#$(#%$6457

8(%.!.$!#. (.$% .000
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Thanks for your attention!

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