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Invited talk (40 min, 29 slides). OBSERVATION OF OCTUPOLE DRIVEN RESONANCE PHENOMENA WITH SPACE CHARGE AT THE CERN PROTON SYNCHROTRON. M. Giovannozzi, M. Martini, R. Steerenberg (CERN), G. Franchetti, I. Hofmann (GSI). E. Métral. with. 14-18 October 2002 22-29 September 2003. - PowerPoint PPT Presentation
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Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
1/29
OBSERVATION OF OCTUPOLE DRIVEN
RESONANCE PHENOMENA WITH SPACE CHARGE
AT THE CERN PROTON SYNCHROTRON
Invited talk (40 min, 29 slides)Invited talk (40 min, 29 slides)
E. MétralE. Métral M. Giovannozzi, M. Martini, R. Steerenberg M. Giovannozzi, M. Martini, R. Steerenberg (CERN), G. Franchetti, I. Hofmann (GSI)(CERN), G. Franchetti, I. Hofmann (GSI)withwith
2 measurement campaigns: 14-18 October 2002 22-29 September 2003
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
2/29
Mechanism anticipated by G. Franchetti & I. Hofmann, which involves Space charge tune spread Nonlinear (octupole) resonance Synchrotron motion
INTRODUCTION
Qx
Qy
hQ
vQ Regime where continuous loss occurs Due to longitudinal motion
Qx
QyvQ
hQ
Regime of loss-free core-emittance blow-up
Particles diffuse into a halo
xQ xQ
yQyQ Regime of loss-free core-emittance blow-up
Regime where continuous loss occurs Due to longitudinal motion
254 xQ
See Giuliano’s talk on Tuesday
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
3/29
EXPERIMENTAL SETUP
Time [ms]
170180
300 1200
Injection
1st profile measurement with a Fast Wire Scanner
(20 m/s)
Last profile measurement
Powering of the octupole
1 octupole pulsed with -3
3 m 1.215 IK m 7.11x m 2.22y
310
Profile measurement in H
Profile measurement in V m 6.11y
m 6.12x m 3.2xD
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
4/29
OTHER BEAM AND MACHINE PARAMETERS
Parameter Value Unit
Circumference 628 m
Horiz. / vert. beam pipe diameter 14 / 7 cm
Superperiodicity 10
Kinetic energy 1.4 GeV
Vert. tune 6.12
Horiz. tune 6.24 < Qx < 6.32
# of bunches 1
# of protons per bunch ~ 1012
Bunch length (4σ) ~ 180 ns
Horiz. / vert. normalised rms emittances ~ 5 / ~ 2.5 mm mrad
Rms momentum spread ~ 1.410-3
Horiz. / vert. rms beam sizes ~ 7 / ~ 4 mm
Derived horiz. / vert. SC tune shifts ~ - 0.075 / ~ - 0.125
Synchrotron period ~ 1.5 ms
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
5/29
FIRST MEASUREMENT CAMPAIGN: 14-18 OCTOBER 2002 (1/3)
Loss dominated regime Emittance growth dominated regime
A 40octI
xQ
G. Franchetti et al.,PRSTAB, 6, 124201 (2003)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
6/29
6.27xQ
[ms] Time
1010bN
Octupole ON (40 A)
170 300 1200
50% of losses
FIRST MEASUREMENT CAMPAIGN: 14-18 OCTOBER 2002 (2/3)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
7/29
Conclusions of the data analysis by Ingo&Giuliano
Emittance growth in good agreement with predictions
Losses not yet completely explained
Re-do measurements in 2003
Use the “real” nonlinear model of the PS machine instead of the constant focusing approximation
FIRST MEASUREMENT CAMPAIGN: 14-18 OCTOBER 2002 (3/3)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
8/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (1/21)
Octupole turned on at 300 ms, measurements at 1200 ms
0
0.5
1
1.5
2
-100 -50 0 50 100
Octupole current [A]
Rel
ativ
e ch
ang
es
I/ini (Qx=6,28)
epsx/ini (Qx=6,28)
I/ini (Qx=6,29)
epsx/ini (Qx=6,29)
Vert. emittance equal (here only) to
the horiz. one
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
9/29
A 20octI
xQ
6.265
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (2/21)
6.25
G. Franchetti et al.,ICFA workshop, Bensheim,
Germany, October 2004
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
10/29
Qx=6.285
1
1.1
1.2
1.3
1.4
1.5
180 380 580 780 980 1180
Time [ms]
Re
lati
ve
ch
an
ge
s
epsx/ini
epsy/ini
Octupole ON
Emittance growth dominated regime
A 20octI
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (3/21)
1 standard deviation
of 5 measurements
Precision of the emittance measurements ~10%
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
11/29
Qx=6.285
7
7.2
7.4
7.6
7.8
8
8.2
180 380 580 780 980 1180
Time [ms]
Ho
rizo
nta
l rm
s b
eam
siz
e [m
m]
From Gaussian fit
Rms computation
A 20octIOctupole ON
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (4/21)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
12/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (5/21)
180 ms
1200 ms
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
13/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (6/21)
30 20 10 10 20 30POSITIONmm
200
400
600
800
1000
HORIZONTAL PROFILE 1st profile and Gaussian fit
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
14/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (7/21)
30 20 10 10 20 30POSITIONmm
200
400
600
800
1000
HORIZONTAL PROFILE Last profile and Gaussian fit
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
15/29
Qx=6.265
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
180 380 580 780 980 1180
Time [ms]
Re
lati
ve
ch
an
ge
s
epsx/ini
epsy/ini
Octupole ON
Beam loss dominated regime
A 20octI
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (8/21)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
16/29
Qx=6.265
5.9
6.1
6.3
6.5
6.7
6.9
7.1
7.3
7.5
180 380 580 780 980 1180
Time [ms]
Ho
rizo
nta
l rm
s b
eam
siz
e [m
m]
From Gaussian fit
Rms computation
A 20octIOctupole ON
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (9/21)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
17/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (10/21)
180 ms
1200 ms
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
18/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (11/21)
30 20 10 10 20 30POSITIONmm
200
400
600
800
HORIZONTAL PROFILE 1st profile and Gaussian fit
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
19/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (12/21)
30 20 10 10 20 30POSITIONmm
200
400
600
800
HORIZONTAL PROFILE Last profile and Gaussian fit
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
20/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (13/21)
180 ms
1200 ms
Undershoot due to the measurement
device
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
21/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (14/21)
50 100 150 200 250 300 350 400TIMEns
2
4
6
8
LONGITUDINAL PROFILE1st profile and Gaussian fit
Undershoot due to the measurement
device
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
22/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (15/21)
100 200 300 400TIMEns
2
4
6
8
LONGITUDINAL PROFILELast profile and Gaussian fit
Undershoot due to the measurement
device
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
23/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (16/21)
From Gaussian fits of previous profiles
Integrated intensity of previous profiles
Octupole ON
G. Franchetti et al.,ICFA workshop, Bensheim,
Germany, October 2004
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
24/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (17/21)
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
6.245 6.25 6.255 6.26 6.265 6.27 6.275 6.28 6.285 6.29 6.295 6.3 6.305 6.31 6.315 6.32
I/iniepsx/iniI/ini w/o OCTepsx/ini w/o OCTI/ini w/o OCT, deb.epsx/ini w/o OCT, deb.epsy/ini w/o OCT, deb.
A 20octI
xQ
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
25/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (18/21)
Debunched beam with octupole OFF
Qx=6.315
Qx=6.245
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
26/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (19/21)
Qx=6.315
Qx=6.245
Debunched beam with octupole OFF
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
27/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (20/21)
20 15 10 5 5 10 15 20POSITIONmm
200
400
600
800
1000
VERTICAL PROFILE 1st profile and Gaussian fit
Same kind of vertical distributions
observed in the previous measurements (due to
PSB and/or injection process)
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
28/29
SECOND MEASUREMENT CAMPAIGN: 22-29 SEPTEMBER 2003 (21/21)
20 15 10 5 5 10 15 20POSITIONmm
200
400
600
800
1000
VERTICAL PROFILE Last profile and Gaussian fit
Elias Métral, COULOMB’05, Senigallia (AN), Italy, September 12-16, 2005
29/29
By lowering the working point towards the resonance 4 Qx = 25, a gradual transition from a regime of loss-free core emittance blow-up to a regime dominated by continuous beam loss has been observed, as expected by Ingo&Giuliano
Emittance growth in good agreement with predictions
Beam losses now better explained than in 2002 (using the nonlinear model of the PS machine instead of the constant focusing approximation)
The observed maximum losses (~30%) are still larger than predicted (~8%)
HOWEVER, with octupole OFF ~20% of maximum beam losses are already observed! May explain the difference
CONCLUSION