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s x * Limitations and Improvements Paths. Damping Rings. Maxim Korostelev, Frank Zimmermann. ATF single-bunch emittances: ge x ~3.5-4.3 m m (CLIC: ~0.5 m m) ge y ~13-18 nm (CLIC: 3 nm) ge z ~8640 eVm (CLIC: <5400 eVm) 6D phase-space density in CLIC ~70 times higher

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s x * Limitations and Improvements Paths

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S x limitations and improvements paths
sx* Limitations and Improvements Paths

Damping Rings

Maxim Korostelev, Frank Zimmermann

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

ATF single-bunch

emittances:

gex~3.5-4.3 mm

(CLIC: ~0.5 mm)

gey~13-18 nm

(CLIC: 3 nm)

gez~8640 eVm

(CLIC: <5400 eVm)

6D phase-space density

in CLIC ~70 times higher

how can we go further?

ATF

CLIC

?

new

CLIC?

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

2004: CLIC-NLC comparison for ITRP “Wise Men”

*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” 26 March 2006


Further progress in 2005
further progress in 2005

also: less charge per bunch

Frank Zimmermann, CLIC “Away Day” 26 March 2006


Possible approaches for achieving even smaller emittance
possible approachesfor achieving even smaller emittance

  • larger damping-ring circumference

    (weaker arcs & longer wigglers)

    + increased beam energy

    2) damping in linac

    3) laser wiggler?

Frank Zimmermann, CLIC “Away Day” 26 March 2006


Larger circumference higher energy
larger circumference + higher energy

MAD-X calculation

w/o IBS

horizontal emittance is 100 nm w/o IBS at 3.74 GeV

not self-consistent,

artificially kept longitudinal emittance at constant value (4500 eVm),

opening-angle effect not included

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

analytical equations including

IBS (Bane approx.) & opening angle

H. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004

opening angle

dispersive terms

IBS

Frank Zimmermann, CLIC “Away Day” 26 March 2006


Result of my analytical calculation
result of my analytical calculation

includes opening angle

Karl Bane’s IBS approximation

almost self-consistent (sz fixed = 1 mm)

for case 2x circumference,

I find large discrepancy in ez

(w/o IBS) between analytical

formula and MAD-X!?

Frank Zimmermann, CLIC “Away Day” 26 March 2006


Exact calculation by maxim
exact calculation by Maxim

best

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

exact calculation by Maxim cont’d

>10% larger sextupole strength implies >10% smaller dynamic aperture

Frank Zimmermann, CLIC “Away Day” 26 March 2006


New ring parameters
new ring parameters?

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

2) damping in linac

H. Braun, M. Korostelev, F. Zimmermann, CLIC Note 594, 2004

wiggler parameters

quite challenging

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

3) laser wiggler

naturally small period

assume laser parameters of Snowmass Posipol Proposal (CLIC note 639)

laser wiggler equivalence:

undulator regime!

~6% transverse

emittance reduction

per laser collision!

however sd→50%!

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

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 gex & gey;

but expect impact on dynamic aperture

~10% & 6x increased heat load

Frank Zimmermann, CLIC “Away Day” 26 March 2006


Spare slide
spare slide

Frank Zimmermann, CLIC “Away Day” 26 March 2006


S x limitations and improvements paths

DR equilibrium emittance without IBS & w/o 1/g

present design:

above can also be written as

Frank Zimmermann, CLIC “Away Day” 26 March 2006


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