CEPC magnet error study Summary
CEPC magnet error study
summary
Sha Bai
CEPC AP meeting
2015-12-25
From: LEP Design Report---------LEP2 P177
LEP Alignment parameters
Magnet Field error 1
From: LEP Design Report---------LEP P18
Magnet Field error 2
From: LEP Design Report---------LEP P19
Magnet Field error 3
BEPCII
CEPC
BEPCII Dynamic aperture
Coupling factor
=0.015 for emitty
without error
with misalignment errors
With all errors
With all B*L and multipole errors
CEPC DA with field errors
with only ¾ ring
With ¾ ring (B,Q,S) B*L errors
2% (1
σ
x, 3.5
σ
y
)
With ¾ ring (B,Q,S) B*L and multipole errors
1.5%, 2% (0, 0)
Coupling factor
=0.003 for emitty
CEPC DA with field errors
with only ¾ ring
With all FFS B*L and multipole errors
enlarge
with ¾ ring and FFS (B,Q,S) B*L errors & multipole
errors
Coupling factor
=0.003 for emitty
1.5%, 2% (0, 0)
Magnet field error on DA
•
With Bend magnet field errors, orbit is changed, and tune is also changed a little bit
•
Orbit correction is needed
•
With Quadrupole and sextupole field errors, orbit has no change.
•
With Quad field errors, tune is change.
•
Bend is set to be bend, but Quad and Sextupole are set to be MULT
•
Tracking in 240 turns, coupling factor
κ
=0.003 for
ε
y
Magnet field error on DA
•
With all (B,Q,S) B*L field errors, whole ring including FFS.
•
Tune has changed a lot:
μ
x
=
0.0510854
μ
y
=
0.1526778
•
Orbit correction and tune adjust are needed
•
Bend set to bend, and Quad and Sext set to be MULT
•
Tracking in 240 turns, coupling factor
κ
=0.003 for
ε
y
Multipole errors effect on DA
•
Off-momentum DA is not changed obviously, with 2% (1
σ
x
, 10
σ
y
)
•
Tune is kept, no effect on tune
•
Orbit is kept to be zero, no effect on orbit
•
Bend is set to be bend, but quadrupole and sextupole are set to be MULT
•
When bend set to be MULT, it doesn’t work in SAD
•
Tracking in 240 turns, Coupling factor
=0.003 for emitty
CEPC field error summary
•
The multipole errors in the main ring seems to have a large effect on the
2% off-momentum DA.
•
The field errors in the FFS seems to have a large effect on the vertical on-
momentum DA.
方案一
：
Optimization of DA
(
前提是
without error
情况下的
DA
足够好
）
轨道校正
（
针对
misalignment errors
）
工作点校正
（
针对
quad B*L error
）
FMA analysis , add octupole, decapole, dodecapole
…….
方案二
：
Reduce errors
(
可能对磁铁制造要求比较高
）
reduce the errors to the DA that we can accept
即使模拟能做好但实际情况未必
……
Error correction
Orbit correction with
correctors & BPM
Tune correction &
chromaticity correction
Impossible to correct
& adjust level to
requirement
Magnet requirement
•
二四六极铁的准直能做到几十个微米（比如30个微米算很好了）
•
校正子二极铁一般提磁场均匀度，约在1%量级。
•
磁铁的场强误差一般不提（因调整电流即可调节场的大小）
•
高阶场误差达到万分之二已经非常好了
,
具体每一高阶场还有差
异，越低阶的高阶场越难做好。
Summary
•
With correctors and BPMs adding in the beam line, SAD harsh table
has no space. SAD can not deal with large ring. MAD can’t give correct
DA. We have to change to other program –BMAD, which can both
give DA and use MAD lattice. And also orbit correction should add
pretzel, Bmadz can deal with every kinds of problem in pretzel.
•
Tune correction and chromaticity correction are not needed for
magnet design requirement.
•
Multipole errors are studied in detail to get a general range of
multipole errors influence on DA.
In preparation for the CEPC AP meeting on 2015-12-25, an analysis was conducted regarding the magnet errors in the system. The study summarized the findings and implications of these errors, shedding light on potential improvements and areas for further research.
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Presentation Transcript
CEPC magnet error study summary Sha Bai CEPC AP meeting 2015-12-25
LEP Alignment parameters From: LEP Design Report---------LEP2 P177
Magnet Field error 1 From: LEP Design Report---------LEP P18
Magnet Field error 2 From: LEP Design Report---------LEP P19
BEPCII CEPC bend quad sext bend quad sext Dx(mm) 0.2 0.15 0.15 0.3 0.1 0.15 Dy(mm) 0.2 0.15 0.15 0.2 0.1 0.15 Tilt(mrad) 0.1 0.2 0.5 0.1 0.1 0.5 B*L 3e-4 3e-4 2e-3 5e-4 5e-4 4e-3 3e-4 8e-4 quadrupole (s) sextupole(s) 6e-4 5e-5 2e-4 6e-4 7e-5 6e-4 7e-5 5e-4 1.7e-3 Octupole(s) 5e-4 9e-5 2e-4 1.3e-4 6.9e-4 3.4e-3 Decapole(s) 6e-4 5e-4 1.4e-4 1e-3 6.5e-3 Dodecapol e(s) Quadrupol e(r) Sextupole(r) 1e-4 3e-4 2e-4 1e-4 1e-4 3e-3 2.9e-4 1.2e-3 1e-4 1e-4 3e-4 2e-4 1e-3 2e-2 Multipole(r)
BEPCII Dynamic aperture with misalignment errors without error y y y y 300 300 250 250 dp p 2 dp p 2 dp p 1.5 dp p 1.5 200 200 dp p 1 dp p 1 dp p 0.5 dp p 0.5 dp p 0 dp p 0 150 150 dp p 0.5 dp p 0.5 dp p 1 dp p 1 100 100 dp p 1.5 dp p 1.5 dp p 2 dp p 2 50 50 x x x x 40 20 0 20 40 40 20 0 20 40 With all errors With all B*L and multipole errors y y y y 200 200 dp p 2 dp p 2 150 150 dp p 1.5 dp p 1.5 dp p 1 dp p 1 dp p 0.5 dp p 0.5 dp p 0 dp p 0 100 100 dp p 0.5 dp p 0.5 dp p 1 dp p 1 dp p 1.5 dp p 1.5 50 50 dp p 2 dp p 2 x x x x 40 20 0 20 40 40 20 0 20 40 Coupling factor =0.015 for emitty
CEPC DA with field errors with only ring Coupling factor =0.003 for emitty y y y y 6 200 5 dp p 2 150 dp p 1.5 dp p 2 4 dp p 1 dp p 1.5 dp p 0.5 3 dp p 0 100 dp p 1.5 dp p 0.5 2 dp p 1 dp p 2 dp p 1.5 1 50 dp p 2 x x 10 5 0 5 10 x x 40 20 0 20 40 2% (1 x, 3.5 y) With ring (B,Q,S) B*L errors y y y y 200 10 dp p 2 8 150 dp p 1.5 dp p 2 dp p 1 6 dp p 1.5 dp p 0.5 dp p 0 100 dp p 1.5 4 dp p 0.5 dp p 2 dp p 1 2 dp p 1.5 50 dp p 2 x x 3 2 1 0 1 2 3 x x 20 10 0 10 20 1.5%, 2% (0, 0) With ring (B,Q,S) B*L and multipole errors
CEPC DA with field errors with only ring Coupling factor =0.003 for emitty y y y y 200 80 dp p 2 dp p 2 150 60 dp p 1.5 dp p 1.5 dp p 1 dp p 1 dp p 0.5 dp p 0.5 dp p 0 dp p 0 100 40 dp p 0.5 dp p 0.5 dp p 1 dp p 1 dp p 1.5 dp p 1.5 50 20 dp p 2 dp p 2 x x x x 40 20 0 20 40 20 10 0 10 20 With all FFS B*L and multipole errors enlarge y y y y 40 10 dp p 2 8 30 dp p 1.5 dp p 2 dp p 1 6 dp p 0.5 dp p 1.5 dp p 0 20 dp p 1.5 4 dp p 0.5 dp p 1 dp p 2 dp p 1.5 2 10 dp p 2 x x 3 2 1 0 1 2 3 x x 20 10 0 10 20 with ring and FFS (B,Q,S) B*L errors & multipole errors 1.5%, 2% (0, 0)
Magnet field error on DA With Bend B*L error Orbit in X & Y With Quad B*L error With Sext B*L error (whole ring including FFS) With Bend B*L error (whole ring including FFS) (whole ring including FFS) x= 0.0720634 y= 0.2261286 (whole ring including FFS) x= 0.0815080 y= 0.1937457 Tune no change With Bend magnet field errors, orbit is changed, and tune is also changed a little bit Orbit correction is needed With Quadrupole and sextupole field errors, orbit has no change. With Quad field errors, tune is change. Bend is set to be bend, but Quad and Sextupole are set to be MULT Tracking in 240 turns, coupling factor =0.003 for y
Magnet field error on DA y y 100 dp p 2 80 dp p 1.5 dp p 1 60 dp p 0.5 dp p 0 dp p 0.5 40 dp p 1 dp p 1.5 dp p 2 20 x x 40 20 0 20 40 With all (B,Q,S) B*L field errors, whole ring including FFS. Tune has changed a lot: x=0.0510854 y= 0.1526778 Orbit correction and tune adjust are needed Bend set to bend, and Quad and Sext set to be MULT Tracking in 240 turns, coupling factor =0.003 for y
Multipole errors effect on DA Bend multipole errors (whole ring including FFS) Quad multipole errors Sextupole multipole errors(whole ring including FFS) (B,Q,S)multiple errors (whole ring including FFS) (whole ring including FFS) Off-momentum DA is not changed obviously, with 2% (1 x, 10 y) Tune is kept, no effect on tune Orbit is kept to be zero, no effect on orbit Bend is set to be bend, but quadrupole and sextupole are set to be MULT When bend set to be MULT, it doesn t work in SAD Tracking in 240 turns, Coupling factor =0.003 for emitty
CEPC field error summary The multipole errors in the main ring seems to have a large effect on the 2% off-momentum DA. The field errors in the FFS seems to have a large effect on the vertical on- momentum DA. Optimization of DA ( without error DA misalignment errors quad B*L error FMA analysis , add octupole, decapole, dodecapole . Reduce errors ( reduce the errors to the DA that we can accept
Error correction Misalignment & bending magnet strength error Orbit correction with correctors & BPM Tune correction & chromaticity correction Error correction Quad strength error Impossible to correct & adjust level to requirement Multipole error
Magnet requirement 30 1% ,
Summary With correctors and BPMs adding in the beam line, SAD harsh table has no space. SAD can not deal with large ring. MAD can t give correct DA. We have to change to other program BMAD, which can both give DA and use MAD lattice. And also orbit correction should add pretzel, Bmadz can deal with every kinds of problem in pretzel. Tune correction and chromaticity correction are not needed for magnet design requirement. Multipole errors are studied in detail to get a general range of multipole errors influence on DA.
