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Frank Zimmermann, CLIC “Away Day” 28 March 2006
x* Limitations and Improvements Paths
Damping Rings
Maxim Korostelev, Frank Zimmermann
Frank Zimmermann, CLIC “Away Day” 28 March 2006
ATF single-bunch emittances:x~3.5-4.3 m (CLIC: ~0.5 m)y~13-18 nm (CLIC: 3 nm)z~8640 eVm (CLIC: <5400 eVm)
6D phase-space density in CLIC ~70 times higher
how can we go further?
?
ATF
CLICnew CLIC?
Frank Zimmermann, CLIC “Away Day” 28 March 2006
2004: CLIC-NLC comparison for ITRP “Wise Men” NLC DR CLIC DR
energy 1.98 GeV 2.42 GeV*
circumference ~299 m 364 m
arc cell length ~6 m 1.8 m
hor. phase advance/arc cell* 108o 210 o
#arc TME cells* ~30-40? 100
total wiggler length* 44 m 152 m
wiggler period* 27 cm 10 cm
bunch population 7.6-15.2x109 4.2x109
longit. emittance , s 10.6 keVm 5.5 keVm
transv. emittances x, y ~3000 nm, 30 nm 660 nm, 3.3 nm
damping times x,y, s 3.63, 4.08 ms, 2.18 ms 2.64 ms,1.32 ms
*smaller emittance due to smaller bend angle / arc cell,less emittance detuning, more damping, smaller Hx in wiggler
*higher energy reduces intrabeam-scattering effect
Frank Zimmermann, CLIC “Away Day” 28 March 2006
further progress in 2005Wiggler 1
permanent magnet
Wiggler 3
Nb3Sn superconductor
Bw 1.7 T 2.5 T
w 10 cm 4.5 cm
x 550 nm
(133 nm w/o IBS)
354-375 nm
(79 nm w/o IBS)
y 3.3 nm
(0.8 nm w/o IBS)
2.9-2.3 nm
(0.5 nm w/o IBS)
z 4724 eVm
(2551 eVm w/o IBS)
4817-4997 eVm
(3433 eVm w/o IBS)also: less charge per bunch
Frank Zimmermann, CLIC “Away Day” 28 March 2006
possible approachesfor achieving even smaller emittance
1) larger damping-ring circumference
(weaker arcs & longer wigglers)
+ increased beam energy
2) damping in linac
3) laser wiggler?
Frank Zimmermann, CLIC “Away Day” 28 March 2006
1) larger circumference + higher energy
not self-consistent,artificially kept longitudinal emittance at
constant value (4500 eVm), opening-angle effect not included
w/o IBS horizontal emittance is 100 nm w/o
IBS at 3.74 GeV
MAD-X calculation
Frank Zimmermann, CLIC “Away Day” 28 March 2006
4/3,
4/3,
22/12/1ˆ43232
;
ˆ2
15322/12
4/3,
4/3,
2/7
ˆ43,2
;
ˆ2
15322/12
4/3,
4/3,
2/7
ˆ43,2
ˆ3
152
32,1;
ˆ)(ˆ
)1()(2
ˆ2
)1()(2
ˆ2ˆ2
2
3
2
22
2/1
2
3
2
22
2/1
2
3
2
53
yNxNw
sB
Bdwws
wsN
B
Bdwwp
syNxN
B
Bdwwx
wyN
B
Bdwwp
syNxN
B
Bdww
w
B
Bddrwwp
wxN
BE
g
a
fRBRE
a
g
lRRg
aE
h
RBRa
b
lRRg
aE
h
RBRa
blRRB
a
b
w
d
w
dr
w
d
w
dr
w
d
w
d
analytical equations including IBS (Bane approx.) & opening angle
H. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004
dispersive terms opening angle
IBS
Frank Zimmermann, CLIC “Away Day” 28 March 2006
result of my analytical calculation
includes opening angle
Karl Bane’s IBS approximation
almost self-consistent (z fixed = 1 mm)
for case 2x circumference,I find large discrepancy in z
(w/o IBS) between analyticalformula and MAD-X!?
Frank Zimmermann, CLIC “Away Day” 28 March 2006
exact calculation by Maxim“nominal” 2x arc 2x arc
2x straights
2x straights
E 2.42 GeV 3.74 GeV 3.74 GeV 3.74 GeV
C 365 m 529 m 704 m 530 m
x 375 nm
(79 nm)
421 nm
(73 nm)
340 nm
(66 nm)
315 nm
(135 nm)
y 2.3 nm
(0.5 nm)
2.65 nm
(0.5 nm)
2.14 nm
(0.415 nm)
1.98 nm
(0.862 nm)
z 4997 eVm
(3433 eVm)
5030 eVm
(4100eVm)
4975 eVm
(4221 eVm)
5020 eVm
(4480 eVm)
best
Frank Zimmermann, CLIC “Away Day” 28 March 2006
exact calculation by Maxim cont’d
“nominal” 2x arc 2x arc
2x straights
2x straights
Q’x -102 -187 -200 -114
Q’y -135 -254 -266 -148
SF
[103 m-3]
7.85 14.1 15.0 8.76
SD
[103 m-3]
-9.99 -18.2 19.3 -11.06
>10% larger sextupole strength implies >10% smaller dynamic aperture
Frank Zimmermann, CLIC “Away Day” 28 March 2006
new ring parameters?present option
circumference 357 m 530 m
energy 2.424 GeV 3.746 GeV
rf frequency 1.875 GHz
rf voltage 2.39 MV 20.5 MV
energy loss/ turn 2.19 MeV 18.93 MeV
total wiggler length
152 m 304 m
synchr. radiation power
0.3 MW 1.9 MW
Frank Zimmermann, CLIC “Away Day” 28 March 2006
2) damping in linacH. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004
damping factor 2
beam energy 34 GeV
addt’l linac length 640 m / side (~1/Bw)
addt’l voltage 48 GV (~1/Bw)
wiggler peak field Bw 10 T
wiggler period w 1.5 cm
x,y 1.5 m, 8 m
final x 272 nm (~x w2 Bw
3)
final y 3.5 nm (~y Bw )
wiggler parametersquite challenging
Frank Zimmermann, CLIC “Away Day” 28 March 2006
3) laser wigglernaturally small periodassume laser parameters of Snowmass Posipol Proposal (CLIC note 639)
2laser
w
laserw IZ
cB 02
2laser wiggler equivalence:
zyx
laserlaser
cAI
2/32type YAG
Alaser 592mJ
w 0.53 m
x,y 5 m
z 0.9 mm
Ilaser 5x1020 W/m2
Bw 4090 T
Tm 01.0Tm 002.0 wwBundulator regime!
7-min,; 106.9
10
3
laser
cyxN
13.0
ionGeV/collis 4.43
16 22
E
E
ArE e ~6% transverseemittance reductionper laser collision!however →50%!
Frank Zimmermann, CLIC “Away Day” 28 March 2006
conclusions
laser wiggler → unacceptable energy spread
superconducting wiggler in linac beyond present state of the art
double wiggler length & increase beam energy to 3.74 GeV→15% reduction in x & y; but expect impact on dynamic aperture ~20-30% & 6x increased heat load
Frank Zimmermann, CLIC “Away Day” 28 March 2006
spare slide
Frank Zimmermann, CLIC “Away Day” 28 March 2006
DR equilibrium emittance without IBS & w/o 1/
7.9/1/1 22 arcw
6.1// 33 arcw
HH present design:
11.0 ,15
8/
/1/11
//1
min3
23
22
3333
FC
NH
HH
J
FC
ww
w
w
arcw
arcw
x
arcqx
arcdiparcww
arcarcdipwwww
x
arcqx LlLB
LlLB
J
FC2222
5525233
const1
const1
above can also be written as