Drive Beam Generation in CTF3 S. Bettoni (CERN) for the CTF3 commissioning team
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Transcript of Drive Beam Generation in CTF3 S. Bettoni (CERN) for the CTF3 commissioning team
Drive Beam Generation in CTF3S. Bettoni (CERN) for the CTF3 commissioning team
Talk outlineDrive beam manipulation:o Combiner ring (factor 4)o Delay loop (factor 2)o Delay loop AND combiner ring (factor 8)
Beam delivery to CLEX
Conclusions
CTF3 for CLIC
fully loaded acceleration
recombination x 2
phase-coding
bunch length control
recombination x 4
bunch compression
PETS on-off
two-beamacceleration
structures 12 GHz
structures 30 GHz
deceleration stability
StructuresStructure materialsDrive Beam generation PETS on-offDB deceleratorCLIC sub-unit
CTF3 is a small scale version of the CLIC drive beam complex: Provide the RF power to test the CLIC accelerating structures and components Full beam-loading accelerator operation Electron beam pulse compression and frequency multiplication Safe and stable beam deceleration and power extraction High power two beam acceleration scheme
Achievements in the past
Beam routinely sent during the week-ends to the PETS structures
MKS03 MKS07MKS06MKS05 To the rings
To the 30 GHz test stand
Measured RF to beam efficiency: 95.3 %
Expected from the theory: 96%
The status of the machine up to CLIC08: Provide the RF power to test the CLIC accelerating structures and components (since 2005)
Full beam-loading accelerator operation (since 2004)
Electron beam pulse compression and frequency multiplication (since 2006)
RF pulse with beam
RF pulse without beam
Analog signal
*AFTER THE CURE OF THE VERTICAL INSTABILITY IN THE RF DEFLECTOR, D. ALESINI (LNF) ET AL.
*
CTF3 operation scenarios
DBA CRDL
TBTSCLEX
CTF3
CTF2
#1
<30A
#2
CRDL
CTF3
14 ACLEXCTF2 TBTS
#3
CRDL
CTF3
4 ACLEXCTF2 TBTS
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
Delay loop: the recombination
0 500 1000 1500 2000 2500
6
4
2
0
t [ns]
I [A
]
2007
Delay loop: improvement of the recombination
ONGOING
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
PUT A COUPLE OF 180º PHASE SWITCHES IN THE TRANSIENT PART OF THE TRAIN
THE FIRST PHASE SWITCH INTRODUCES DIFFERENT
LOADING
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
Delay loop: current stability
CL.SVBPM1590S CT.SVBPM0515S Min. (A) -3.858 -6.300 Max. (A) -3.828 -6.234 Mean (A) -3.845 -6.277 Std (A) 0.007 0.014
Variation (%) 0.17 0.22
Through DLBy-passing DL
Delay loop: control of the optics
Delay loop optics:
Control of the optics enough to have successful recombination (betas and dispersion)
Small adjustments (order of %) necessary to have full transmission (worse for the model):o Identified regions of model/machine discrepancies by means of kick measurements
The optics is quite transparent for the beam
Combiner ring: the recombination
2008
Combiner ring: current stability
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
Combiner ring: control of the optics
20 21 22 23 24 250
0.2
0.4
0.6
0.8
1
IQ560 (A)
Frac
tiona
l par
t of t
he tu
nes
Qx (measured)
Qx (simulated)
Qy (measured)
Qy (simulated)
0 20 40 60 80 100
-0.5
0
0.5
1
s (m)
Dx (m
)
Model (at BPM only)Model (all the elements)Measurement
To validate the MAD-X model of the combiner ring: High precision kick measurements compared to the model predictions:
o Symmetric kick analysis to identify single quadrupole erroro Multi-turn analysis to magnify the effect of the discrepancy
Other independent measurements are used to check the correction:o Dispersiono Tunes
TURN 1 TURN 2 TURN 3
P. Skowronski
The status of the machine up to CLIC08: Provide the RF power to test the CLIC accelerating structures and components (since 2005)
Full beam-loading accelerator operation (since 2004)
Electron beam pulse compression and frequency multiplication (2009)
NowAchievements in the pastThe status of the machine up to CLIC08:
Provide the RF power to test the CLIC accelerating structures and components (since 2005)
Full beam-loading accelerator operation (since 2004)
Electron beam pulse compression and frequency multiplication (2006-present)
Delay loop & combiner ring: THE recombination
ONLY DL
ONLY CRDL & CR
New lines installed in 2008/2009
42.5 m
8 m
2m
D FFD
DF
F
D F DDUMPD F D
F
FD
ITB
1.85m
CALIFES Probe beam injectorLIL-ACSLIL-ACSLIL-ACSD F D
D F D
DFDUMP
0.75
1.4m
1
DUMP
22.4 mTBL
2.5m
Transport path
DUMP
DUMP 22 m2.0m
DF DF DF DF DF DF DF DF
3.0m3.0m6 m
D F DF DF D
16.5 mTBTS16 m
TL2’
42.5 m42.5 m
8 m8 m
2m2m
D FFFDD
DF
FDD
FF
FF
D F DD F DDUMPD F DD F D
F
FD
F
FD
F
FD
ITB
1.85m1.85m
CALIFES Probe beam injectorLIL-ACSLIL-ACSLIL-ACSLIL-ACSLIL-ACSLIL-ACSD F DD F D
D F DD F D
DF DFDUMP
0.75
1.4m1.4m
11
DUMP
22.4 m22.4 mTBL
2.5m2.5m
Transport path
DUMP
DUMP 22 m22 m2.0m2.0m
DF DF DF DF DF DF DF DFDF DF DF DF DF DF DF DF DF DF DF DF DF DF DF DF
3.0m3.0m3.0m3.0m6 m6 m
D F DD F DF DF DF DF D
16.5 m16.5 mTBTS16 m16 m
TL2’
DRIVE BEAM LINAC
Injector
CLEX
30 GHZ test stand
30 GHz power station
DELAY LOOP
COMBINERRINGchicane
TL1
TL2
probe beam linac
two-beam test stand
TBL - decelerator
CTF3 – Main components
New lines installed: TL2 → transfer line from CR to the CLEX area CLEX area:
o TBL → study the drive beam stability during the decelerationo TBTS → test the two-beam acceleration schemeo CALIFES → probe beam linac
RRCAT
Module-1 Horizontal achromat
Module-3 Tunable R56 (from -0.35
to +0.35) Achromatic arc Final matching doublet
Module-2 Straight section for tail
clipper Vertical achromat Matching section
Going to CLEX
3x
4x
TWISS PARAMETERS FOR THE DIFFERENT EXTRACTED TURNS QUITE SIMILAR
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
Transfer line 2: control of the optics
CR
TL2
Steps of the commissioning: New MTV monitor installed in the line during the 2008/2009 winter shut down Commissioning made more difficult by the BPM not working properly yet (work in
progress) Uncombined beam transported almost to the end of the line, combined with more
losses Kick measurements evidenced two regions where the model and the machine don’t
agree (check on the two identified quadrupoles this week)
CR combined beam
Uncombined beam
The control of the orbitIn CTF3 the control of the orbit is more critical than in other machines:
The efficiency of the recombination depends on the ring length The subpulses which go through the DL must be put on top of the ones which go straight The orbit of the recombined subpulses in the CR is the superposition of more orbits The closure of the orbit in the CR is crucial also for the transport of the recombined beam
Input: Maximum tolerance Maximum strength of the correctors Response matrix measured or from the model (CR)
111
1
1
1
1
,, yxI
I
yIorbitV
I
xIorbitH
j
kk
j
kkk
jTurn
j
kk
j
kkk
jTurn
measured
ONGOINGInput:
Maximum tolerance on:o The orbit difference o The overall orbit excursion
Maximum strength of the correctors
CTF3 reliabilityFully loaded operation mode + RF compression don’t make CTF3 reliable “for free”:
Orbit references (Indian collaboration)
RF loading and beam current references (tool to do it automatically to be tested)
Phase loop (A. Dubrovskiy, CERN)
ConclusionsSEVERAL OF THE CTF3 GOALS HAVE BEEN ALREADY DEMOSTRATED IN THE PAST YEARS:
Fully loading operation mode (consistent with theory predictions) First demonstration in delay loop
2009 MILESTONES: Successful factor 4 recombination achieved Successful factor 2 recombination in delay loop obtained Factor 2x4 recombination putting in operation delay loop AND combiner ring Beam through PETS in the CLEX area
FUTURE SHORT TERM PROGRAMS: Improve the reliability and the stability of the machine Further optics studies in the delay loop and in the new lines Test of the two beam acceleration scheme in CLEX (acceleration and stability studies)
SPARE SLIDES
Measurements in TL2
CC.QDH0220 = -23 %CC.QFL0530 = +20 %
Delay loop: fast phase switch & satellites
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
666 ps
1 8
Streak camera image
mainsatellite
Fast phase switch from SHB system
Gap creation and x2 multiplication
odd buckets
even buckets Delay
Loop
RF deflector
Combination scheme
Ldelay = n l0 = c Tsub-pulse Phase coding
180 phase switch
Acceleration n0
Deflection n0 / 2
Sub-Harmonic Bunching n0 / 2
How to “code” the sub-pulses
Combiner ring multiplication
3rd
lo/4
4rd
2ndinjection line
septum
localinner orbits
1st deflector 2nd deflector
1st turn
lo RF deflector field
Fully loaded operation mode
Lstruct
loaded
Gacc
s
unloaded
E0
t
tfill
steady state E0 /2
Ebeam
400300
-5
0
5
time (nsec)
P/P (%)
P1050Central =107.5MeV/c
-50
5
600
700
800
900-10-5
05
10-1
-0.5 0 0.5 1
P/P (%)
Ppeak =108.5 MeV/c, PFWHH =11.68%
600700
800900
0 1 2 3 4 5
IBeam (A)
time (nsec)
600700
800900
108
110
112
Ppeak (MeV/c)
time (nsec)600
700800
9001 2 3
PFWHH (%)
200100
Transient
Steady stateP/P
(%)
Time (ns)
Time resolved beam energy spectrum measurement in CTF3
THE recombination: current stability
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
DRIVE BEAM LINAC
CLEXCLIC Experimental Area
DELAY LOOP
COMBINERRING
10 m
4 A – 1.2 ms150 Mev
32 A – 140 ns150 Mev
CL.SVBPM0502S CT.SVBPM0515S CR.SVBPM0155SMin. (A) -4.085 -5.322 -25.585Max. (A) -4.067 -5.280 -24.255Mean (A) -4.078 -5.308 -25.210Std (A) 0.005 0.011 0.254
Variation (%) 0.13 0.20 1.01
FIRST MEASUREMENT
(NOT BEST CONDITIONS)
THE END