Oper. Experience with High Current Particle Accels. [pres. slides]

29 Pages·2003·3.584 MB·English

by  S. Belomesnykh

ββββ
OPERATING EXPERIENCE WITH = 1 HIGH CURRENT
ACCELERATORS
S. Belomestnykh
11th Workshop on RF-Superconductivity SRF 2003 September 9, 2003
Talk overview
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Functions of the fundamental RF systems
q Deliver RF power to a high-current beam(s)
q Provide high voltage for high synchrotron tune and short bunch
length (colliders)
q Provide enough voltage for good quantum lifetime (light sources)
q Provide voltage for good energy acceptance (both)
q Suppress parasitic interaction of a beam with higher-order modes
(HOMs) by providing good HOM damping (concept of so-called
HOM-damped, HOM-free or single-mode cavity)
( )
= ⋅ + +
P I U U U
V beam beam 0 hom para
c
synchronous particle
α⋅ ⋅ ϕ
h V sin
= c s
f f
s rev
π
2 E e
⋅α σ
c
σ = ⋅
E
z
ω
E
s
φ
s
SC HOM damped cavity concept
Large beam tubes:
– Reduces the interaction of the beam with the
cavity
– HOMs are removed easily better beam
stability higher beam current accelerated
HOMs are loaded using one of the following
(or both):
– Beam line ferrite absorbers (CESR, KEKB)
– Broad- and narow- band loop couplers (LHC, SOLEIL)
Fundamental SRF systems
Systems in operation
q CESR: four 500 MHz Nb cavities
q KEKB HER: eight 509 MHz Nb cavities
Beam test
q SOLEIL cryomodule in ESRF: two 352 MHz cavities
Cavity tests
q LHC (hadron collider): sixteen 400 MHz Nb/Cu cavities
q CLS (light source): one CESR-style cryomodule
Future systems
q TLS (light source): one CESR-style cryomodule
q DIAMOND (light source): two CESR-style cryomodules
q BEPC II (e+e- collider and light source): two CESR- or KEKB-
style cryomodules
KEK B-factory HER
KEKB HER: 8 GeV e- storage ring
Resonant frequency 508.887 MHz
R/Q 93 Ohm
Q 109
0
Q 7××××104
ext
Operating temperature 4.5 K
Accelerating voltage 1.5 MV
KEKB: achieved performance
Posters: MoP07, MoP21, MoP20, ThP33
××××
Peak luminosity 1.0567 1034 cm-2s-1
Beam current 1.1 A
RF voltage with beam 1.2 – 2.0 MV/cavity
××××
Q 1 – 2 109 at 2 MV
0
××××
0.3 – 1 109 at 2.5 MV
Max. power 380 kW/cavity
transferred to beam
HOM power 10 kW/cavity at 1.1 A
Highlights:
• 1996: Beam test in the TRISTAN AR
• 1998: First four SRF cavity installed in
KEKB HER
• 2000: Four more cavities added
KEKB future development: crab cavities
Posters: MoP34, ThP23
CESR-III high luminosity e+e-collider
4 superconducting B-cell cavity cryomodules
Resonant frequency 499.765 MHz
R/Q 89 Ohm
Q 109
0
Q 2××××105
ext
Operating temperature 4.5 K
Accelerating voltage up to 3 MV
Static heat leak 30 W
Highlights:
• 1994: Beam test, first demonstration of high
current operation
• 1997: First SRF cavity installed in CESR for
routine operation
• 1999: First storage ring to run entirely on
SRF cavities
CESR-III performance
××××
Peak luminosity 1.3 1033 cm-2s-1
Beam current 0.78 A
RF voltage with beam 1.85 MV/cavity (1.6 – 2)
××××
Q 1 109 at 2 MV Qo BB1Qvs.EaccSummary
0
0.3 – 1 ××××109 at 2.7 MV 1.E+10
BB1-1(W1),PA BB1-4(E1),PA1/10/01
Max. power 300 kW/cavity BB1-7(W2),PA7/2/02 BB1-6(E2),PA6/11/03
transferred to beam (360 kW forward power)
HOM power 5.7 kW/cavity at 0.75 A
1.E+09
1.E+08
2 3 4 5 6 7 8 9 10
Eacc,MV/m