electron cloud diagnostics in the sps machine
DESCRIPTION
Electron Cloud Diagnostics in the SPS Machine. G. Arduini 1 , V. Baglin 3 , P. Collier 1 , B. Dehning 2 , G. Ferioli 2 , B. Henrist 3 , N. Hilleret 3 , B. Jenninger 3 , L. Jensen 2 , J.M. Jimenez 3 , J.M. Laurent 3 , K. Weiss 3 , F. Zimmermann 4 1 SL/OP, 2 SL/BI, 3 LHC/VAC, 4 SL/AP - PowerPoint PPT PresentationTRANSCRIPT
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Electron Cloud DiagnosticsElectron Cloud Diagnosticsin the SPS Machinein the SPS Machine
G. Arduini1, V. Baglin3, P. Collier1, B. Dehning2,
G. Ferioli2, B. Henrist3, N. Hilleret3,
B. Jenninger3, L. Jensen2, J.M. Jimenez3,
J.M. Laurent3, K. Weiss3, F. Zimmermann4
1SL/OP, 2SL/BI, 3LHC/VAC, 4SL/AP CERNCERN, Geneva, Switzerland
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: bunch intensity, threshold
• Intensity threshold : August 1999: 4.3x1010 p/b April 2000: 6.4x1010 p/b
Pressures do not vary appreciably up to a threshold bunch intensity and then, increase with the bunch intensity.
Amplitude of the signals measured on the pick-up also increase with the bunch intensity.
• Influence of a magnetic field Threshold in magnetic field free regions: 6.0 to 7.0x1010 p/b
Threshold in dipole magnetic fields: 3.0 to 4.0x1010 p/b
Cannot be attributed to systematic errors since the gauges do not resent the magnetic field. One explanation could come from the simulations which showed that the electrons of the e- cloud are confined in the vertical plane in a dipole magnetic field (F. Zimmerman).
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: bunch intensity- No magnetic field -
0
2
4
6
8
10
0.0E+00 2.0E+10 4.0E+10 6.0E+10 8.0E+10 1.0E+11Protons bunch intensity
P/P
Duty cycle ~ 45 %after 17h integratedtime of LHC beam
threshold
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: bunch intensity
- Dipole magnetic field -
0
2
4
6
8
10
12
14
0.E+00 1.E+10 2.E+10 3.E+10 4.E+10 5.E+10 6.E+10 7.E+10 8.E+10 9.E+10 1.E+11
Proton bunch intensity
P/P
Duty cycle ~ 45 %after 17h integratedtime of LHC beam
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: bunch intensity- No magnetic field -
6.9x1010 p/b21 bunches visible
LHC-type beam characteristics: 1 batch of 72 bunches
8.3x1010 p/b41 bunches visible
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: bunch intensity, threshold
Magnetic field free region
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: bunch intensity, threshold
Dipole magnetic field region
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Scrubbing effect
• Scrubbing effect observed in the SPS Pressure rises decrease with time 30 times after about 2.5 integrated
days of LHC-type beam e- cloud activity no longer affect pressures Threshold bunch intensity increased from 4.0x1010 in August 1999 up to
6.6x1010 in June 2000 Clear indication of a modification of the characteristics of the surface
• N2 glow discharge against e- cloud First cycle of experiments showed no difference between the non-
treated and treated chambers After air exposure, treated chamber showed a memory of the scrubbing
Scrubbing effect is effective up to the bunch intensity used for the commissioning. Pressure will rise for higher bunch intensities
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Scrubbing effect
P/P = 27xe-1.2t
1
10
100
0:00 12:00 24:00 36:00 48:00 60:00LHC beam time (hh:mm)
P
/P
VG51540
VG51833
VG52940
Dipole magnetic field (MBB/MBB)Duty cycle: 45%
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Scrubbing effect
P/P = 33xe-1.5t
1
10
100
0:00 12:00 24:00 36:00 48:00 60:00LHC beam time (hh:mm)
P
/P
VG51890VG51880
No magnetic fieldDuty cycle: 45%
Remind
Remind
erer
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
“Strip” detector
300
Beam
Vacuum chamber
Strip detector
Holes
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
“Strip” detector
holes
- Holes distribution -
Transparency of 7.5 % to avoid the extinction of the multipacting
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
“Strip” detector
Strips
Connecting
wires
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Triangle detector- Holes distribution -
Transparency of 42 % to avoid the extinction of the multipacting
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Triangle detector
Vacuum chamberBeam
Filtering grid
Detecting plates
Holes
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Triangle detector
Vacuum chamber
Beam
Filtering gridDetecting plates
Holes
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Reference plate
“Triangle detector”
Beam
axis
Measuring plate
Grid to avoid an extinction of the e- cloud
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Strip detector calibration
-16.5 -14.0 -11.5 -9.0 -6.5 -4.0 -1.5 1.0 3.5 6.0 8.5 11.0 13.5 16.0 18.5 21.0S1
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nsity
(arb
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ts)
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25-50
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Signal expected without holes
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nsity
(arb
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Lateral position (mm)
150-175
125-150
100-125
75-100
50-75
25-50
0-25
Signal expected without holes
Varying the bump amplitude to see the effect
of the holes on the vacuum chamber
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, threshold
Threshold before (April 2000) and after venting (July 2001)
Field free region
0
2
4
6
8
10
0.0E+00 1.0E+10 2.0E+10 3.0E+10 4.0E+10 5.0E+10 6.0E+10 7.0E+10 8.0E+10 9.0E+10 1.0E+11
Protons bunch intensity
P/P
25/07/200117/04/2000
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, threshold
Threshold before (April 2000) and after venting (July 2001)
Dipole field region
0
2
4
6
8
10
12
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16
18
20
0.E+00 1.E+10 2.E+10 3.E+10 4.E+10 5.E+10 6.E+10 7.E+10 8.E+10 9.E+10 1.E+11
Proton bunch intensity
P/P
25/07/2001
17/04/2000
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, threshold
Threshold of the e- cloud in a dipole field
Limit of detection: 4.2x10-7 A/m2
Magnetic field: 2000 Gauss
0.0E+00
1.0E-05
2.0E-05
3.0E-05
4.0E-05
5.0E-05
6.0E-05
7.0E-05
8.0E-05
0.0E+00 1.0E+10 2.0E+10 3.0E+10 4.0E+10 5.0E+10 6.0E+10 7.0E+10
Protons/bunch
Inte
nsi
ty (
A/m
2 )
After 7 h of LHC beam
(above the threshold: 2.0x10-10 p/b)
First measurementswith LHC beams
Measurements made with 48 bunches in the batch
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
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uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
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ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, thresholdMeasurements made with 48 bunches in the batch
Strip width as a function of the bunch intensity
Limit of detection: 4.2x10-7 A/m2
Magnetic field: 2000 Gauss
0
5
10
15
20
25
0.0E+00 1.0E+10 2.0E+10 3.0E+10 4.0E+10 5.0E+10 6.0E+10 7.0E+10
Protons/bunch
Str
ip w
idth
(m
m @
2
)
After 7 h of LHC beam
(above the threshold: 2.0x10-10 p/b)
First measurementswith LHC beams
file MD_25-07-2001-std-LHC-beam-threshold
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
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uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
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rist
, N. H
iller
et B
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ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, threshold
Appearance of two strips for high intensity beam (>6.0 1010 p/b)
-17 -14 -12 -9 -7 -4 -2 1 4 6 9 11 14 16 19 21S1
S4
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S34S37
S40S43
S46
1.E-06
3.E-06
5.E-06
7.E-06
9.E-06
1.E-05
Inte
nsi
ty (
A/m
2 )
Transverse position (mm)
Tim
e (ms)
t = 10 m
s
9.00E-06-1.10E-057.00E-06-9.00E-065.00E-06-7.00E-063.00E-06-5.00E-061.00E-06-3.00E-06
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
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uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
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rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, threshold
0
1
2
3
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5
6
7
8
9
10
11
12
0.0E+00 2.0E+10 4.0E+10 6.0E+10 8.0E+10 1.0E+11
Bunch intensity (p/b)
Dis
tan
ce b
ea
m a
xis/
strip
(m
m)
y = 2.10-10x - 7
R2 = 0.959
Pumping holes in the LHC beam screen
Two strips at high intensities
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
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uini
, V. B
aglin
, P. C
ollie
r, B
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ning
, G. F
erio
li, B
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rist
, N. H
iller
et B
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ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, threshold
Energy distribution of the electrons in the cloud
1.0E-07
1.0E-06
1.0E-05
1.0E-04
600 1100 1600 2100 2600 3100
Time (ms)
e- clo
ud
in
ten
sity
(A
/m)
0
50
100
150
200
250
300
Fil
teri
ng
po
ten
tial
(V
)
Strip channel 5Strip channel 7e- cloud signal measuredFiltering grid potential
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
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uini
, V. B
aglin
, P. C
ollie
r, B
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ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, thresholdEnergy distribution of the electrons in the cloud
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 50 100 150 200 250 300 350
Electron energy (eV)
Pe
rce
nta
ge
(%
)
75 eV
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
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uini
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aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
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rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch intensity, thresholdEffect of the magnetic field on the energy
distribution of the electrons in the cloud
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 50 100 150 200 250 300
Electron energy (eV)
Per
cen
tag
e (%
)
30 A
15 A
5 A
2.5 A
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
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ning
, G. F
erio
li, B
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rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Bunch lengthEffect of the bunch length on the electrons in the cloud
-19
-14 -9 -4 1 6
11 16
S1
S6
S11
S16
S21
S26
S31
S36
S41
S46
S51
S56
S61
S66
S71
S76
S81
S86
S91S96S101
0255075
100125150175200
Intensity
Transverse position (mm)
175-200
150-175
125-150
100-125
75-100
50-75
25-50
0-25
-19
-14 -9 -4 1 6
11 16
S1
S6
S11
S16
S21
S26
S31
S36
S41
S46
S51
S56
S61
S66
S71
S76
S81
S86
S91S96S101
0255075
100125150175
Intensity
Transverse position (mm)
150-175
125-150
100-125
75-100
50-75
25-50
0-25
150 Gauss2100 GaussB
unch
leng
th: 5
ns -
> 2
ns
Bun
ch le
ngth
: 5ns
->
2ns
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Filling pattern
1
5
9
13
S1
S8
S15
S22
S29
S36
S43
S50
S57
S64
S71
S78
S85
S92
S99
S106
S113
S120
050
100150200250300350400450500550600650
600-650
550-600
500-550
450-500
400-450
350-400
300-350
250-300
200-250
150-200
100-150
50-100
0-50
Effect of the injection of three batches in the SPS
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Filling pattern
y = 10-7x
R2 = 0.9888
0.0E+00
1.0E-07
2.0E-07
3.0E-07
4.0E-07
5.0E-07
6.0E-07
7.0E-07
8.0E-07
9.0E-07
-20 -15 -10 -5 0 5 10 15 20
Lateral position (mm)
Inte
ns
ity
(A
/m)
0.0E+00
5.0E-07
1.0E-06
1.5E-06
2.0E-06
2.5E-06
3.0E-06
3.5E-06
4.0E-06
4.5E-06
Tota
l in
ten
sit
y (
A/m
)
1 batch
2 batches
3 batches
I e- cloud = f( nbre ofbatches)Linear (I e- cloud = f(nbre of batches))
Effect of the injection of three batches in the SPS
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Beam effects: Filling pattern
0.0E+00
2.0E-07
4.0E-07
6.0E-07
8.0E-07
1.0E-06
1.2E-06
1.4E-06
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
Time (ms)
Inte
nsi
ty (
A/m
)
Ch 01 : 8 bucket spacing
Ch 01 : 21 bucket spacing
Ch 01 : 21 bucket spacing
Ch 02 : 21 bucket spacing
Effect of an increase of the batch spacing
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Dipole field effect: Bunch intensity, threshold
-19
-4
11
S1
S11
S21
S31
S41
S51
S61
S71
S81
S91
S101
S111
S121
S131S141
S151S161
S171S181
1.0E-042.0E-043.0E-044.0E-045.0E-046.0E-047.0E-048.0E-049.0E-041.0E-03
Inte
ns
ity
(A
/m2 )
Transverse position
(mm)
9.0E-04-1.0E-03
8.0E-04-9.0E-04
7.0E-04-8.0E-04
6.0E-04-7.0E-04
5.0E-04-6.0E-04
4.0E-04-5.0E-04
3.0E-04-4.0E-04
2.0E-04-3.0E-04
1.0E-04-2.0E-04
No e- cloud
detected
-200 G
+200 G
Magnetic field passing through 0 Gauss
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Dipole field effect: Bunch intensity, threshold
Magnetic field passing through 0 Gauss
Limit of detection: 4.2x10-7 A/m2
0.0E+00
1.0E-04
2.0E-04
3.0E-04
4.0E-04
5.0E-04
6.0E-04
-160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160
Field strength (Gauss)
Inte
ns
ity
(A
/m2)
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Dipole field effect: Bunch intensity, threshold
e- cloud intensity as a function of the dipole magnetic field
Limit of detection: 4.2x10-7 A/m2
0.0E+00
1.0E-04
2.0E-04
3.0E-04
4.0E-04
5.0E-04
6.0E-04
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200
Magnetic field (Gauss)
Inte
ns
ity
(A
/m2 )
782653
782648
782547
782519
782504
Starting from 1200 GStarting from 2200 G
Starting from 200 G
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Dipole field effect: Bunch intensity, threshold
Limit of detection: 4.2x10-7 A/m2
0.00E+00
5.00E-05
1.00E-04
1.50E-04
2.00E-04
2.50E-04
3.00E-04
3.50E-04
4.00E-04
4.50E-04
5.00E-04
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Time (ms)
Str
ip in
ten
sit
y (
A/m
2 )
0
300
600
900
1200
1500
1800
2100
2400
Ma
gn
eti
c f
ield
(G
au
ss
)
782491
782496
782504
Mag. Field
e- cloud intensity as a function of the dipole magnetic field
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Dipole field effect: Bunch intensity, threshold
Strip width as a function of the dipole magnetic field
-19 -16 -14 -11 -9 -6 -4 -1 1 4 6 9 11 14 16 19
S1
S4
S7
S10
S13
S16
S19
S22
S25
S28
S31
S34
S37
S40
S43
S46
S49
0255075
100125150175200225250
Intensity
Transverse position (mm)
225-250
200-225
175-200
150-175
125-150
100-125
75-100
50-75
25-50
0-25
-19 -16 -14 -11 -9 -6 -4 -1 1 4 6 9 11 14 16 19
S1
S4
S7
S10
S13
S16
S19
S22
S25
S28
S31
S34
S37
S40
S43
S46
S49
0255075
100125
150
175
200
225
Intensity
Transverse position (mm)
200-225
175-200
150-175
125-150
100-125
75-100
50-75
25-50
0-25
-19 -16 -14 -11 -9 -6 -4 -1 1 4 6 9 11 14 16 19
S1
S4
S7
S10
S13
S16
S19
S22
S25
S28
S31
S34
S37
S40
S43
S46
S49
0255075
100125
150
175
200
225
Intensity
Transverse position (mm)
200-225
175-200
150-175
125-150
100-125
75-100
50-75
25-50
0-25
-19 -16 -14 -11 -9 -6 -4 -1 1 4 6 9 11 14 16 19
S1
S4
S7
S10
S13
S16
S19
S22
S25
S28
S31
S34
S37
S40
S43
S46S49
0
25
50
75
100
125
Intensity
Transverse position (mm)
100-125
75-100
50-75
25-50
0-25
2100 Gauss 1100 Gauss
550 Gauss 200 Gauss
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Dipole field effect: Bunch intensity, threshold
Strip width as a function of the dipole magnetic field
Limit of detection: 4.2x10-7 A/m2
0
5
10
15
20
25
30
35
40
45
0 500 1000 1500 2000 2500
Magnetic field (Gauss)
Wid
th (
mm
@ 2
)
782653
782648
782606
782590
782574
782519
782504
782496
782491
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Conclusions• Beam effects: bunch intensity, threshold, bunch length
– Dipole field regions: threshold measured at 2.0x1010 p/b– 3.0x1010 p/b in 2000
– Field free regions: threshold measured at 5.0x1010 p/b– 6.0x1010 p/b in 2000
– lower threshold measured could be explained by the venting of the whole SPS to air during the long shutdown.
Below the threshold of the field free region, when the dipole magnetic field is switched off, the e- cloud signal immediately disappeared.
The bunch length affects strongly the e- cloud, decreasing the bunch length from 5ns to 2ns increase the intensity by 50%.
• Current density– Above the threshold, the current increases linearly, up to
5.5x1010 p/b, no saturation effect was observed
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Conclusions• Width of the e- cloud
– The width of the e- cloud strip increases with the beam intensity. At 6.0x1010 p/b, the width is already bigger than 20mm and therefore, the first line of holes (7.5 mm from the axis) in the beam screen sees the e- cloud. With the present design of the beam screen, the e- cloud will see the second line (11.5mm from the axis) at an intensity of 7.0x1010 p/b.
• Effect of the magnetic field strength on the e- cloud– A strong effect of the dipole field strength on the e- could
behavior was shown, mainly for field below 200 G.– Below 20 Gauss, the electron cloud disappears and a
maximum was found around 50 gauss. This effect does not affect the LHC since the field at
injection is about 5500 Gauss
SPS Working Group, 09 October 2001prepared by J.M. Jimenez, CERN Division LHC - Vacuum GroupG
. Ard
uini
, V. B
aglin
, P. C
ollie
r, B
. Deh
ning
, G. F
erio
li, B
. Hen
rist
, N. H
iller
et B
. Jen
ning
er, L
. Jen
sen,
J.M
. Jim
enez
, J.M
. Lau
rent
, K. W
eiss
, F. Z
imm
erm
ann
Electron Cloud Diagnostics in the SPS Machine
Conclusions
• Beam scrubbing– After 7h of LHC-type beam (integrated time above the
threshold of 2.0x1010 p/b in the dipole field region), no cleaning effect is visible.
This result is consistent with the measurements of last year presented in EPAC.
Only low intensities <5.0x1010 p/b with small duty cycle (~ 5-10%) were used. This limitation was imposed by the fixed-target beam blow up induced by the e- cloud pressure rises