beam scrubbing: specifications of beams and transverse stability considerations
DESCRIPTION
Beam scrubbing: specifications of beams and transverse stability considerations. Many thanks to: T. Argyropoulos , T. Bohl , S. Cettour Cave, K. Cornelis , H. Damerau , J. Esteban Muller, F. Follin , S. Hancock, W. Hofle , C. Lazaridis , L. Kopylov , H. Neupert , - PowerPoint PPT PresentationTRANSCRIPT
Beam scrubbing: specifications of beams and transverse stability considerations
G. Iadarola, H. Bartosik, N. Mounet, G. Rumolo
Many thanks to:T. Argyropoulos, T. Bohl, S. Cettour Cave, K. Cornelis, H. Damerau,
J. Esteban Muller, F. Follin, S. Hancock, W. Hofle, C. Lazaridis, L. Kopylov , H. Neupert, Y. Papaphilippou, B.Salvant, E. Shaposhnikova, M. Taborelli, C. Zannini
and the SPS operator crew
Outline
• Electron cloud and scrubbing at the SPS
• A “doublet” scrubbing beam for the SPSo Simulation studieso First tests at the SPS
• Stability considerationso First observationso e-cloud driven instabilitieso Impedance driven instabilities
G. Arduini, K. Cornelis et al.
400%
Electron cloud and scrubbing at the SPS
• In the past e-cloud has been strongly limiting the performances with LHC beams with 25 ns spacing (detrimental effects both on vacuum and beam quality)
• Scrubbing runs regularly performed over the years with evident beneficial effects on dynamic pressure rise and beam quality
• Status in 2012: No degradation due to e-cloud for nominal beam parameters. Emittance blow up observed on trailing bunches of the last batches for larger bunch population
2000 (48 b. - 0.8x1011 ppb @inj.)
G. Arduini, K. Cornelis et al.
400%
Electron cloud and scrubbing at the SPS
• In the past e-cloud has been strongly limiting the performances with LHC beams with 25 ns spacing (detrimental effects both on vacuum and beam quality)
• Scrubbing runs regularly performed over the years with evident beneficial effects on dynamic pressure rise and beam quality
• Status in 2012: No degradation due to e-cloud for nominal beam parameters. Emittance blow up observed on trailing bunches of the last batches for larger bunch population
2000 (48 b. - 0.8x1011 ppb @inj.)
G. Arduini, K. Cornelis et al.
400%
Electron cloud and scrubbing at the SPS
• In the past e-cloud has been strongly limiting the performances with LHC beams with 25 ns spacing (detrimental effects both on vacuum and beam quality)
• Scrubbing runs regularly performed over the years with evident beneficial effects on dynamic pressure rise and beam quality
• Status in 2012: No degradation due to e-cloud for nominal beam parameters.
• Emittance blow up observed on trailing bunches of the last batches for larger bunch population
2000 (48 b. - 0.8x1011 ppb @inj.)
2012 (288 b. - 1.35x1011 ppb @inj.)
G. Arduini, K. Cornelis et al.
400%
Electron cloud and scrubbing at the SPS
• In the past e-cloud has been strongly limiting the performances with LHC beams with 25 ns spacing (detrimental effects both on vacuum and beam quality)
• Scrubbing runs regularly performed over the years with evident beneficial effects on dynamic pressure rise and beam quality
• Status in 2012: No degradation due to e-cloud for nominal beam parameters. Emittance blow up observed on trailing bunches of the last batches for larger bunch population
2000 (48 b. - 0.8x1011 ppb @inj.)
2012 (288 b. - 1.45x1011 ppb @inj.)
2012 (288 b. - 1.35x1011 ppb @inj.)
Scrubbing runs at the SPS
• ~1-2 weeks periods (typically once per year) devoted to condition the beam chambers (i.e. lower the Secondary Electron Yield) by means of the electron cloud itself
• Scrubbing is performed at the injection energy for the LHC type beams (26 GeV) in cycling mode refilling the machine every ~40 s
• The achievable dose rate is typically limited by heating and/or outgassing on some sensitive machine elements (e.g. kickers, septa, beam dumps)
Scrubbing runs at the SPS
• ~1-2 weeks periods (typically once per year) devoted to condition the beam chambers (i.e. lower the Secondary Electron Yield) by means of the electron cloud itself
• Scrubbing is performed at the injection energy for the LHC type beams (26 GeV) in cycling mode refilling the machine every ~40 s
• The achievable dose rate is typically limited by heating and/or outgassing on some sensitive machine elements (e.g. kickers, septa, beam dumps)
43.2 s
Scrubbing runs at the SPS
• ~1-2 weeks periods (typically once per year) devoted to condition the beam chambers (i.e. lower the Secondary Electron Yield) by means of the electron cloud itself
• Scrubbing is performed at the injection energy for the LHC type beams (26 GeV) in cycling mode refilling the machine every ~40 s
• The achievable dose rate is typically limited by heating and/or outgassing on some sensitive machine elements (e.g. kickers, septa, beam dumps)
43.2 s
Beam requirements for scrubbing
• The beam parameters need to be chosen in order to maintain a strong e-cloud flux on the chamber’s wall
• Integrated dose is more important than peak flux need for a reliable operation, reduce stress on sensitive machine elements
• Beam quality requirements less tight than for the LHC filling but only as long as it does not compromise the scrubbing efficiency
Beam requirements for scrubbing
• The beam parameters need to be chosen in order to maintain a strong e-cloud flux on the chamber’s wall
• Integrated dose is more important than peak flux need for a reliable operation, reduce stress on sensitive machine elements
• Beam quality requirements less tight than for the LHC filling but only as long as it does not compromise the scrubbing efficiency
Beam requirements for scrubbing
• The beam parameters need to be chosen in order to maintain a strong e-cloud flux on the chamber’s wall
• Integrated dose is more important than peak flux need for a reliable operation, reduce stress on sensitive machine elements
• Beam quality requirements less tight than for the LHC filling but only as long as it does not compromise the scrubbing efficiency
2006 Scrubbing Run
E. Benedetto et al.
Outline
• Electron cloud and scrubbing at the SPS
• A “doublet” scrubbing beam for the SPSo Simulation studieso First tests at the SPS
• Stability considerationso First observationso e-cloud driven instabilitieso Impedance driven instabilities
Why do we need a dedicated “scrubbing beam”?
1 1.2 1.4 1.6 1.810
-6
10-5
10-4
10-3
10-2
10-1
100
SEY
Req
. scr
ub
bin
g d
ose
[C
/mm
2 ] What do we need?
Why do we need a dedicated “scrubbing beam”?
1 1.2 1.4 1.6 1.810
-6
10-5
10-4
10-3
10-2
10-1
100
SEY
Req
. scr
ub
bin
g d
ose
[C
/mm
2 ]
1 1.2 1.4 1.6 1.810
-4
10-3
10-2
10-1
100
101
SEY
EC
cu
rren
t (E
e>
50eV
) [m
A/m
]
MBB – 25ns beam
What do we need?
What do we have?
Why do we need a dedicated “scrubbing beam”?
Possible issue:
• The beam is still degraded due to EC
• The dose is not sufficient to continue scrubbing in a reasonable time
Possible solution:
• A “scrubbing beam” which exhibits a lower multipacting threshold
• The 25 ns beam is the ideal scrubbing beam for the 50 ns beam
• What could we used to scrub for the 25 ns beam?
1 1.2 1.4 1.6 1.810
-6
10-5
10-4
10-3
10-2
10-1
100
SEY
Req
. scr
ub
bin
g d
ose
[C
/mm
2 ]
1 1.2 1.4 1.6 1.810
-4
10-3
10-2
10-1
100
101
SEY
EC
cu
rren
t (E
e>
50eV
) [m
A/m
]
MBB – 25ns beam
What do we need?
What do we have?
Why do we need a dedicated “scrubbing beam”?
Possible issue:
• The beam is still degraded due to EC
• The dose is not sufficient to continue scrubbing in a reasonable time
Possible solution:
• A “scrubbing beam” which exhibits a lower multipacting threshold
• The 25 ns beam is the ideal scrubbing beam for the 50 ns beam
• What could we used to scrub for the 25 ns beam?
1 1.2 1.4 1.6 1.810
-6
10-5
10-4
10-3
10-2
10-1
100
SEY
Req
. scr
ub
bin
g d
ose
[C
/mm
2 ]
1 1.2 1.4 1.6 1.810
-4
10-3
10-2
10-1
100
101
SEY
EC
cu
rren
t (E
e>
50eV
) [m
A/m
]
MBB – 25ns beam
Scru
bbin
g be
am
What do we need?
What do we have?
Why do we need a dedicated “scrubbing beam”?
Possible issue:
• The beam is still degraded due to EC
• The dose is not sufficient to continue scrubbing in a reasonable time
Possible solution:
• A “scrubbing beam” which exhibits a lower multipacting threshold
• The 25 ns beam is the ideal scrubbing beam for the 50 ns beam
• What could we used to scrub for the 25 ns beam?
1 1.2 1.4 1.6 1.810
-6
10-5
10-4
10-3
10-2
10-1
100
SEY
Req
. scr
ub
bin
g d
ose
[C
/mm
2 ]
1 1.2 1.4 1.6 1.810
-4
10-3
10-2
10-1
100
101
SEY
EC
cu
rren
t (E
e>
50eV
) [m
A/m
]
MBB – 25ns beam
Scru
bbin
g be
am
What do we need?
What do we have?
A “doublet” scrubbing beam for the SPS
• Due to RF limitations in the PS, impossible to inject bunch to bucket with spacing shorter than 25 ns
• A shorter “effective spacing” can be obtained injecting long bunches from the PS and capturing each bunch in two neighboring buckets train of doublets
0 10 20 30 40 50 60 70
Lo
ng
. be
am p
rofi
le
0 10 20 30 40 50 60 70Time [ns]
E
A “doublet” scrubbing beam for the SPS
• Due to RF limitations in the PS, impossible to inject bunch to bucket with spacing shorter than 25 ns
• A shorter “effective spacing” can be obtained injecting long bunches from the PS and capturing each bunch in two neighboring buckets
0 10 20 30 40 50 60 70Lo
ng
. be
am p
rofi
le
0 10 20 30 40 50 60 70Time [ns]
E
0 10 20 30 40 50 60 70Lo
ng
. be
am p
rofi
le
0 10 20 30 40 50 60 70Time [ns]
E
0 10 20 30 40 50 60 70
Lo
ng
. be
am p
rofi
le
0 10 20 30 40 50 60 70Time [ns]
E
A “doublet” scrubbing beam for the SPS
0 10 20 30 40 50 60 70Lo
ng
. be
am p
rofi
le
0 10 20 30 40 50 60 70Time [ns]
E
0 10 20 30 40 50 60 70Lo
ng
. be
am p
rofi
le
0 10 20 30 40 50 60 70Time [ns]
E
• Due to RF limitations in the PS, impossible to inject bunch to bucket with spacing shorter than 25 ns
• A shorter “effective spacing” can be obtained injecting long bunches from the PS and capturing each bunch in two neighboring buckets train of doublets
25 ns 25 ns
Why should it work?
• Mechanism of e-cloud enhancement
10 20 30 40 50 60 70
0.5
1
1.5
2x 10
11
Bea
m p
rof.
[p
/m]
10 20 30 40 50 60 701
1.05
1.1
1.15
1.2
1.25
1.3
1.35
1.4
Time [ns]
Ne /
Ne(0
)
Below the threshold all the electrons produced after a bunch passage are absorbed before the next one small accumulation over subsequent bunch passages
PyECLOUD simulation
Std 25 ns beam
Why should it work?
• Mechanism of e-cloud enhancement
10 20 30 40 50 60 70
0.5
1
1.5
2x 10
11
Bea
m p
rof.
[p
/m]
10 20 30 40 50 60 701
1.05
1.1
1.15
1.2
1.25
1.3
1.35
1.4
Time [ns]
Ne /
Ne(0
)
More e- production and shorter e- decay accumulation possible
PyECLOUD simulation
Std 25 ns beam
Doublet beam
Simulation study
• The doublet beam shows a lower multipacting threshold compared to the standard 25 ns beam if the intensity is larger than 0.8e11ppb (1.6e11ppb from the PS)
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.30
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0e
V)
[A/m
2]
0.60e11ppb0.70e11ppb0.80e11ppb0.90e11ppb1.00e11ppb1.10e11ppb1.20e11ppb6btc 25ns1.20e11ppb
Intensity per bunch of
the doublet (b.l. 4 ns)
(b.l. 3 ns)
1.15 1.2 1.25 1.3 1.35 1.4 1.4510-6
10-4
10-2
100
102
SEY
Sc
rub
bin
g d
ose
(5
0eV
) [m
A/m
] MBB - 26GeV
PyECLOUD simulation
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.35
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0eV
) [A
/m2 ]
Simulation study
• The scrubbed region is smaller to be used, with radial steering, as a last stage of the scrubbing
MBB - 26GeV PyECLOUD simulation
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.30
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0e
V)
[A/m
2]
0.60e11ppb0.70e11ppb0.80e11ppb0.90e11ppb1.00e11ppb1.10e11ppb1.20e11ppb6btc 25ns1.20e11ppb
Intensity per bunch of
the doublet (b.l. 4 ns)
(b.l. 3 ns)
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• The production scheme has been successfully tested for a train of (2x)72 bunches with 1.7e11 p per doublet
42 660
1
2
3
Time [ms]
200
MH
z R
F V
olta
ge [
MV
]
4
-10
1st inj.
Thanks to T. Argyropoulos and J. Esteban Muller
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• The production scheme has been successfully tested for a train of (2x)72 bunches with 1.7e11 p per doublet
42 660
1
2
3
Time [ms]
200
MH
z R
F V
olta
ge [
MV
]
4
-10
1st inj.
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• The production scheme has been successfully tested for a train of (2x)72 bunches with 1.7e11 p per doublet
42 660
1
2
3
Time [ms]
200
MH
z R
F V
olta
ge [
MV
]
4
-10
1st inj.
0.92 0.94 0.96 0.98 1 1.02-0.02
0
0.02
0.04
0.06
Time [s]
Bea
m p
rofi
le [
a.u
.]T
urn
0.92 0.94 0.96 0.98 1 1.02
100
200
300
400
500
Thanks to T. Argyropoulos and J. Esteban Muller
42 36043600 360235983596359466 359235900
1
2
3
Time [ms]
200
MH
z R
F V
olta
ge [
MV
]
4
-10
1st inj. 2nd inj.
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• The possibility of injecting a second batch without degrading the circulating been has also been shown
42 36043600 360235983596359466 359235900
1
2
3
Time [ms]
200
MH
z R
F V
olta
ge [
MV
]
4
-10
1st inj. 2nd inj.
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• The possibility of injecting a second batch without degrading the circulating been has also been shown
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
First bunch (of 2 single) after the second inj.
After 1st inj.
After 2nd inj.
Profile of the first doublet
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• Clear enhancement observed both on e-cloud detectors and pressure in the arcs
MBA
MBB
First tests at the SPS
First machine tests have been conducted at the SPS at the end of 2012-13 run in order to validate the production scheme and obtain first indications about the e-cloud enhancement
• Clear enhancement observed both on e-cloud detectors and pressure in the arcs
MBA
MBB
25ns std. (1.6e11p/bunch)
(1.7e11p/doublet)25ns “doublet”
Outline
• Electron cloud and scrubbing at the SPS
• A “doublet” scrubbing beam for the SPSo Simulation studieso First tests at the SPS
• Stability considerationso First observationso e-cloud driven instabilitieso Impedance driven instabilities
Stability considerations
Beam quality requirements:
• For SPS scrubbing purposes the goal is to inject up to 4 batches (4 x 72 doublets) and store the beam at injection energy for ~30 s with limited losses and emittance blow-up
• Studies are ongoing in order to assess if this beam can be accelerated to 450 GeV and delivered to the LHC for scrubbing purposes tighter beam quality requirements
The present SPS damper:
• After the LS1 consolidation it will be able to detect and damp the motion of the centroid of each doublet Intra-bunch motion and “pi-mode” of the two bunchlets are not detected
Stability considerations
Beam quality requirements:
• For SPS scrubbing purposes the goal is to inject up to 4 batches (4 x 72 doublets) and store the beam at injection energy for ~30 s with limited losses and emittance blow-up
• Studies are ongoing in order to assess if this beam can be accelerated to 450 GeV and delivered to the LHC for scrubbing purposes tighter beam quality requirements
The present SPS damper:
• After the LS1 consolidation it will be able to detect and damp the motion of the centroid of each doublet Intra-bunch motion and “pi-mode” of the two bunchlets are not detected
Stability considerations
Beam quality requirements:
• For SPS scrubbing purposes the goal is to inject up to 4 batches (4 x 72 doublets) and store the beam at injection energy for ~30 s with limited losses and emittance blow-up
• Studies are ongoing in order to assess if this beam can be accelerated to 450 GeV and delivered to the LHC for scrubbing purposes tighter beam quality requirements
The present SPS damper:
• After the LS1 consolidation it will be able to detect and damp the motion of the centroid of each doublet Intra-bunch motion and “pi-mode” of the two bunchlets are not detected
Tests at the SPS: first instability observations
• The tests were carried out without the transverse damper and with high chromaticity (ξx,y~0.4) Under these conditions, instabilities could be observed even at low bunch intensities
0 1 2 3 4-2
-1
0
1
2
07/02/13 00-38-04
BB
Q s
ign
al,
V.
pla
ne
[a.u
.]
Time [s]
0 1 2 3 40
0.5
1
1.5
2x 1013
To
tal
inte
nsi
ty [
pp
b]
Time [s]
Tests at the SPS: first instability observations
• The tests were carried out without the transverse damper and with high chromaticity (ξx,y~0.4) Under these conditions, instabilities could be observed even at low bunch intensities
0 1 2 3 4-2
-1
0
1
2
07/02/13 00-38-04
BB
Q s
ign
al,
V.
pla
ne
[a.u
.]
Time [s]
0 1 2 3 40
0.5
1
1.5
2x 1013
To
tal
inte
nsi
ty [
pp
b]
Time [s]
300 350 400
0
0.5
1
1.5
2
Inte
ns
ity
[a
.u.]
25 ns slot
At inj.3 sec. after inj.
Electron cloud driven instabilities
• By definition a scrubbing beam works in a severe e-cloud environment and is therefore prone to e-cloud instabilities
7.35 7.36 7.37 7.38 7.39 7.4
x 10-6
0
1
2
3x 1011
Time [s]
Be
am
pro
file
[p
+/m
]
7.35 7.36 7.37 7.38 7.39 7.4
x 10-6
0
5
10
15x 1012 sey = 1.35
e- c
en
tral
de
nsi
ty [
m-3
]
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.30
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0e
V)
[A/m
2]
0.60e11ppb0.70e11ppb0.80e11ppb0.90e11ppb1.00e11ppb1.10e11ppb1.20e11ppb6btc 25ns1.20e11ppb
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.30
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0e
V)
[A/m
2]
0.60e11ppb0.70e11ppb0.80e11ppb0.90e11ppb1.00e11ppb1.10e11ppb1.20e11ppb6btc 25ns1.20e11ppb
PyECLOUD simulation
Electron cloud driven instabilities
• By definition a scrubbing beam works in a severe e-cloud environment and is therefore prone to e-cloud instabilities
7.35 7.36 7.37 7.38 7.39 7.4
x 10-6
0
1
2
3x 1011
Time [s]
Be
am
pro
file
[p
+/m
]
7.35 7.36 7.37 7.38 7.39 7.4
x 10-6
0
5
10
15x 1012 sey = 1.35
e- c
en
tral
de
nsi
ty [
m-3
]
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.30
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0e
V)
[A/m
2]
0.60e11ppb0.70e11ppb0.80e11ppb0.90e11ppb1.00e11ppb1.10e11ppb1.20e11ppb6btc 25ns1.20e11ppb
-0.02 -0.01 0 0.01 0.020
0.2
0.4
0.6
0.8
1sey = 1.30
Position [m]
Sc
rub
bin
g c
urr
en
t (5
0e
V)
[A/m
2]
0.60e11ppb0.70e11ppb0.80e11ppb0.90e11ppb1.00e11ppb1.10e11ppb1.20e11ppb6btc 25ns1.20e11ppb
PyECLOUD simulation
HEADTAIL simulation
Impedance driven instabilities
HEADTAIL simulation studies (considering a single doublet) have been recently started
• Impedance model includes: wall impedance (6 different vacuum chambers, including the magnets iron) + low frequency trapped mode due to MKE kickers with serigraphy
Thanks to C. Zannini
Impedance driven instabilities
HEADTAIL simulation studies (considering a single doublet) have been recently started
• First simulations with zero chromaticity and no transverse damper show an instability with a “p” mode (bunches oscillating rigidly out-of-phase)
1.3 1011 ppb
Impedance driven instabilities
HEADTAIL simulation studies (considering a single doublet) have been recently started
• Dependence of the growth rate on chromaticity has also been investigated
These instabilities have a rise time of at least several thousands of turns so might well be damped by Landau damping from (natural) non-linearities
Summary
• Build up simulation studies have shown that that the “doublet” beam features and
enhanced scrubbing efficiency with respect to the standard 25 ns beam
• The production scheme has been successfully tested at the SPS at the end of
2012-13 run
• First indications from the e-cloud detectors and dynamic pressure rise look very
promising
• During the tests (carried out without transverse damper) instabilities could be
observed
• After LS1 the present SPS damper will be able to detect (and damp) the center of
mass motion of each doublet but will not be able to detect:
o Intra-bunch motion driven by e-cloud
o “pi-mode” driven by machine impedance
• By fighting this kind of instabilities, the high bandwidth feedback would help
preserving the beam quality and therefore increasing the scrubbing efficiency
Thank you for your attention!
100 200 300 400 500 600 700 800 900
10
20
30
40
50
60
70
80
First tests at the SPS
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
First bunch (of 2 single) after the second inj.
After 1st inj.
After 2nd inj.
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
First bunch (of 2 single) after the second inj.
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
First bunch (of 2 single) after the first inj.
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
First bunch, 2nd batch
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
70th bunch, 2nd batch
0 5 10 15 200
0.5
1
1.5
2
2.5
Time [ns]
Lo
ng
itu
din
al b
ea
m p
rofi
le [
a.u
.]
1st bunch, 1st batch
First tests at the SPS
agdsgfsh
MBA-like Stainless Steel liner
25ns standard (1.6e11p/bunch)
25ns “doublet” (1.7e11p/doublet)
First tests at the SPS
agdsgfsh
MBB-like Stainless Steel liner
25ns “doublet” (1.7e11p/doublet)
25ns standard (1.6e11p/bunch)
SPS tests????
72 “doublets”
72 bunches Higher press. rise
Arcs
Arcs