1. S. Bettoni for the CTF3 commissioning team CTF3 commissioning status

2. Outline CTF3 for CLIC Machine commissioning: 2008 milestones:
Combiner ring model improvement
New lines in operation:
TL2
TBTS
CALIFES
2008 milestones:
Factor 4 recombination demonstrated
First drive beam in PETS (w/o and w recirculation)
First probe beam
Bunch length measurement:
RF pickup
Coherent diffraction
Other topics:
Steering algorithms
Transient compensation
The 2009 of CTF3
Conclusions

3. CLIC as a multiTeV collider
Basic features
High acceleration gradient (100 MV/m)
“Compact” collider - overall 3 TeV  50 km
Normal conducting accelerating structures
High acceleration frequency (12 GHz)
Two-Beam Acceleration Scheme
Cost effective, reliable, efficient
Simple tunnel, no active elements
Modular, easy energy upgrade in stages
Drive beam A, 240 ns
from 2.4 GeV to 240 MeV
Main beam – 1 A, 160 ns
from 9 GeV to 1.5 TeV
140 MW

4. CLIC Layout 3 TeV Main beam IP 48.4 km e+ injector, 2.4 GeV
e+ main linac
e- main linac , 12 GHz, 100 MV/m, 21.1 km
BC2
BC1
e+ DR 365m
e- DR 365m
booster linac, 9 GeV
decelerator, 24 sectors of 878 m IP
BDS km
48.4 km
drive beam accelerator GeV, 1.0 GHz
combiner rings Circumferences delay loop 72.4 m CR m CR m
CR1
CR2
Delay loop
326 klystrons 33 MW, 139 ms
1 km
326 klystr 33MW
TA R=120m
245m
e+ PDR 365m
e- PDR 365m
4.2A, 139 ms
Drive beam generation complex
101A, 244 ns
Main beam
Main beam generation complex

5. CTF3: CLIC R&D Issues – WHERE?
Small scale version of the CLIC RF power source
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
recombination
x 4
recombination x 2
bunch length
control
bunch
compression
fully loaded
acceleration
PETS
on-off
structures
12 GHz
30 GHz
two-beam
acceleration
deceleration
stability
phase-coding
Structures
Structure materials
Drive Beam generation
PETS on-off
DB decelerator
CLIC sub-unit

6. CTF3 status in the years 2004 2005 Linac DL CR 2006/7/8
Thermionic gun
Linac DL CR
2006/7/8 D F F F D D D F D F F F D D D F F F D D D F F F D D D F F F D D D F F F D D D F F F D F D D D F F F D D D F F F D D F F F D D D F F F D D F F D D F D F F D D F F F D D D D D D F F F D D D D D F D D D F F F F F D D D D D F D D F D F F D D F F D D
CLEX F D F F D D
CTF2
CLEX
building in 2006/7
30 GHz production
(PETS line)
and test stand
Photo injector / laser
tests from Oct. 2008
TL2 2008
Complete apart from TBL
TL2, TL2’ installed

7. Main points of the commissioning
Delay loop:
2 x current multiplication by DL
TL1:
3.5 A in TL1
Magnetic and RF injection in CR
CR:
Bad cabling quadrupoles
Wrong BPM calibration
Combined function magnets not properly modeled
FAST VERTICAL INSTABILITY

8. The 2008 of CTF3 30 GHz DL & CR 30GHz only RUN 1 DL, CR, TL2 TBTS
Installation: TL2, CALIFES, TBTS
Linac only
Today
RUN 2
Linac, Ring area, (CLEX)
PETS in TBTS
Installations
CALIFES
PETS
CALIFES
RUN 3

9. 2008 CTF3 experimental program
1st run (April - June)
Injector & Linac: establish stable & documented working point, automatic beam steering & steering algorithm studies, diagnostics consolidation, stability studies, EUROTeV BPMs
Delay Loop: complete beam optics measurements (dispersion, orbit, kick measurements, matching), re-establish combination
TL1 & combiner ring: complete optics studies (dispersion, closed orbit correction, matching, tunes, kick measurements, quad displacement evaluation, matching), tune and b function dependence of vertical instability, factor four combination with DL bypass (≥ 10 A)
DL, TL1 & CR: factor 8 combination (≥ 15 A)
2nd run (July - September)
Complete DL + CR, new RF deflectors (20 A ?)
TL2 commissioning
First CALIFES commissioning
TBTS commissioning (no PETS)
3rd run (September - December)
Complete above program
Coherent Diffraction Radiation tests
TBTS, PETS running in

10. 2008 CTF3 experimental program
1st run (April - June)
Injector & Linac: establish stable & documented working point, automatic beam steering & steering algorithm studies, diagnostics consolidation, stability studies, EUROTeV BPMs
Delay Loop: complete beam optics measurements (dispersion, orbit, kick measurements, matching), re-establish combination
TL1 & combiner ring: complete optics studies (dispersion, closed orbit correction, matching, tunes, kick measurements, quad displacement evaluation), tune and b function dependence of vertical instability, factor four combination with DL bypass (≥ 10 A)
DL, TL1 & CR: factor 8 combination (≥ 15 A)
2nd run (July - September)
New RF deflectors, Complete DL + CR (20 A ?)
TL2 commissioning
First CALIFES commissioning
TBTS commissioning (no PETS)
3rd run (September October - December)
Complete above program  First CALIFES commissioning
Coherent Diffraction Radiation tests
TBTS, PETS running in

11. Measurements in CTF3
Several measurements are performed in the machine to validate the optics models:
Response matrix:
High precision method
Symmetric and multiturn kick (ring)
Dispersion measurements
Tune measurements
Steering algorithms applied in the machine:
Ring orbit correction
Dispersion free steering (Linac)
Bunch length measurement
Transient compensation

12. Problem solved since September 2008
Gun instability
Stable
Unstable
CTF3 Linac is fully loaded
The energy transferred to the beam depends on the beam current
Gun instability
(HV fluctuations)
The current is different shot to shot
The energy gain is different shot to shot
Position jitter in dispersive regions
Set up and measurements VERY difficult
Problem solved since September 2008

13. CTF3 commissioning status
Combiner ring
CTF3 commissioning status

14. Combiner ring kick measurements
To maximize the precision of the measurement in the ring:
The multiturn response matrix has been measured: easier to identify the discrepancies
Symmetric kicks analysis: easier to identify a single quad error
Several bugs found
TURN 1
TURN 2
TURN 3

15. Combiner ring: correcting the bugs
Dispersion
Combined function magnets (reused from EPA):
New model of the combined magnets has been used
The k1 strength has been lowered with respect to the one used in the EPA model
Increase of the strength of the J-type quads
Cross-cabled control units for quadrupoles power converter
Tunes

16. Wiggler currents adjusted according to kick measurements
Tune measurements
W/O
correction
Wiggler currents adjusted according to kick measurements W
correction

17. Fast vertical instability disappeared!
current
vertical
horizontal
Old deflectors
BPM signals shoving vertical instability
New deflectors
BPM signals, no instability

18. CTF3 commissioning status
Transfer line TL2
large part done by RRCAT:
Optics design
Aluminium vacuum chambers
Bending magnets
CTF3 commissioning status

19. TL2 optics Module-3 Module-2 Module-1
Tunable R56 (from to +0.35)
Achromatic arc
Final matching doublet
Module-2
Straight section for tail clipper
CLEX-CR buildings not at the same height (achromat)
Matching section
Module-1
From CR extraction point to the first bend magnet (achromat)
Beam direction
For more details see “Optics design”, Amalendu Sharma et al., 2007 CTF3 collaboration meeting, Link

20. Beam setup in TL2 → Quad scan in CTS and tracking to the start of TL2
MTV
TL1
LINAC CT DL
CTS CR
TL2
CLEX
→ Quad scan in CTS and tracking to the start of TL2
→ Uncertainty on the initial conditions:
→ Error in the TL1/CR model
→ Small variations of the quads strength in the TL1/CR model
→ Error in the measurement propagated through TL1 and CR
→ New equipment to read the BP in the line:
→ Some problems at the beginning of the commissioning
→ Relatively strong optics
→ Since a certain time radiation alarm made operation in this area slow and annoying

21. TL2 status at the end of the year
Beam through TL2
→ Uncertainty on the initial conditions:
→ Modified module-2 quads to compensate the possible different initial conditions
→ Found and corrected model-measurements discrepancies in CR (only during this shut down)
→ Installed MTV at the beginning of TL2 (during this shut down)
→ Greatly improved the BPs reading (interactions with LAPP people)
→ Relaxed optics searched
→ Discovered bug:
→ last quadrupole of the first triplet of module-2 had a maximum value lower than the read one (Loic)
TL2 status at the end of the year
BUT …

22. Kick measurements
Kick 615
Kick 435
Kick 125
→ Up to now NO huge discrepancies between the machine and the model found

23. During this shut-down the two exit chicanes were extended
For 2009 run improvements
The operation of the machine was very tedious in the CR extraction zone because of radiation problems. DL
TL1
CRM CR
TL2
CLEX
During this shut-down the two exit chicanes were extended
Tail Clipper installed in TL2:
It is made of kicker and dump that sits just above the beam
It allows to regulate recombined train length
The dump serves as a beam stopper to protect CLEX so It makes possible simultaneous operation of DL/CR and installations in CLEX

24. CLEX (CLIC Experimental area)
existing building D F F F D D D F D F F F D D D F F F D D D F F F D D D F F F D D D F F F D D D F F D F F D D D F F F D D D F F F D D F F F D D D F F F D D F F D F D D D D D F F F F F D D D D D D F D D D D F F F F F D D D D F D F F D D D D F D D F D F D F D D D F F D F D D F F F
Test Beam Line TBL
42.5 m
8 m 2 m D F
DUMP
ITB
1.85m
CALIFES Probe beam injector
LIL -
ACS
0.75
TBL
2.5m
22 m
2.0m
6 m
16.5 m
TBTS
16 m
TL2 ’
ITB (not base-line)
CALIFES Probe beam
Two Beam Test Stand
Probe Beam
Everything installed, apart from TBL
CTF3 commissioning status

25. PETS
A fundamental element of the CLIC concept is two-beam acceleration, where RF power is extracted from a high-current and low-energy beam in order to accelerate the low-current main beam to high energy.

26. Drive beam generation scenarios
CTF3 #1 DL
DBA CR
CTF2
CLEX
TBTS
<30A
CTF3 #2
Operation mode #1 #2 #3
CLIC
Current, A
< 30 14 4
101
Pulse length, ns
140
<240
<1200
240
Bunch Frequency, GHz 12 3
PETS power (12 GHz), MW
<280 61 5
135 DL
14 A CR
CTF2
TBTS
CLEX
CTF3 #3
To produce the CLIC nominal PETS power 22 A drive beam would be necessary. DL
4 A CR
CTF2
CLEX
TBTS

27. PETS with external re-circulation
The recirculation
Variable Splitter
(coupling: 01)
Variable
phase shifter
To the Load
PETS output
Drive
beam
PETS input
PETS with external re-circulation
A fraction of the power going out from PETS is resent to the SAME PETS structure
CLIC nominal
6.0 A
Problem 2008 run:
Splitter: stuck in undefined position (not remotely controllable)
Phase-shifter: stuck in undefined position (not remotely controllable)
5.0 A
4.0 A
3.5 A
240 ns
CLIC
nominal
R. Corsini, I. Syratchev

28. Beam in TBTS PETS story
Total ~ 30 hours integrated conditioning time (15/11/2008 to 15/12/2008)
Gradually increasing current arriving at PETS, up to ~ 5A, 11/12
14/11: First beam
2A w/ recirculation (by chance: positive build-up!)
21/11: Manually forces splitter to extreme position: no recirculation (to verify beam generated RF power)
28/11 : Adjusted phase-shifter : back to constructive recirculation mode

29. The recirculation: measurements
With the maximum current sent to PETS (~5 A) this year 30 MW power obtained instead of less than 5 MW!
Power: PETS out, to load, reflected
Corresponding pulse intensity^2 (the BPM before, and two first after PETS):
E. Adli, R. Corsini, I. Syratchev

30. Very nice according of the modeling with the measurements
The recirculation: model/measurements
Model (power)
Measured (power)
Measured (current)
Very nice according of the modeling with the measurements
E. Adli

31. CALIFES commissioningD F
DUMP
1.85m
CALIFES Probe beam injector
LIL-ACS
TBL
TBTS
TL2’
Dec 1st
Earlier the laser was used by PHIN
The beam with laser pulse train of 100 ns length (150 bunches)
100% transmission through the 1st cavity
Dec 8th
Laser broken
Measurements continued using the dark current
30th March
Restart

32. Several steering algorithms have bee applied in the machine
→ Closed orbit correction (ring)
→ Dispersion free steering (Linac)

33. CR orbit correction algorithm
Best eps value iteratively determined:
→ Tolerance on the maximum allowed beam displacement and maximum value of the currents in the correctors
for i = 1:n_max_step
if i == 1
eps(i) = eps_start*fact;
else
eps(i) = eps(i-1)*fact;
end
[theta_s,thetap_s,corr_s,final_s,idec_s] = correction_1_mod(eps(i),RM',x_BP');
Curr_tot_s(i,:) = start_corr'+theta_s;
Curr_tot_max(i) = max(abs(start_corr'+theta_s));
if abs(Curr_tot_max(i)) > max_I_corrs_tol
fact = 1.1;
x_max_exp = max(abs(x_BP+RM'*theta_s));
if x_max_exp < tol
break
fact = 0.9;
Curr_tot = Curr_tot_s(end,:);
e value
Check and new e value

34. CR response matrix Orbit closure:
→ The response matrix is built using both the first and the second turn orbits
Kick at corrector 242
Correctors
Turn 1
Turn 2
BPM/BPI
Kicks in the correctors to measure the response matrix:
→ The value of the kick in each corrector is determined according to the maximum tolerated losses in the last read BPM/BPI

35. CR orbit correction: the results
Inputs:
→ Tolerated maximum x-displacement = 4 mm
→ Maximum current in the correctors = 10 A
→ Maximum allowed losses = 10%
Tolerance on the orbit correction limited by the incoming orbit jittering

36. Steering algorithms in the Linac
E. Adli
→ The CTF3 linac has been used as a facility of the TBL to test the Beam Based Alignment algorithm
→ Use this technique to steer the beam during the CTF3 linac operation
Structure of the CTF3 linac (not to scale)
→ Studied algorithms:
→ All-to-all (A2A): steers the beam to get BPM zero-readings, by inverting the response matrix of the nominal machine optics
→ Dispersion free steering (DFS): minimizes (at the same time) of the orbit and the dispersion, using the responses corresponding to different optics:
→ Used responses:
→ Measured. Necessary to re-measure it each time the optics changes
→ Model-based. Nice model identification (BPM readings corrector strengths) necessary before

37. Steering algorithms in the Linac: the results
E. Adli
Linac orbit after all-to-all correction
A2A worked well
A2A (measured response) → convergence after 2 iterations
A2A (model response) → convergence after 4 iterations
Comparison between results of Dispersion Free Steering and All-to-All
DFS worked well
Simulated BPM offset:
A2A → residual dispersion ~ 15 mm
DFS → residual dispersion of a factor 3 smaller

38. Bunch length measurements
H. Shaker, A. Dabrowski et al.
M. Micheler et al.
Use the radiation emitted by electrons passing close to a medium
Standard RF deflector and novel RF pickup technique

39. Transient compensation
A. Dabrowski et al.
32 Tungsten plates (2mm thick) spaced by ~1mm
Energy along the pulse measurement
ΔP/P (%)
Steady State
High Energy Transient ~ 40 % > E0
Time (ns)
Nominal RF settings
ΔP/P (%)
Steady State
Transient compensation ~10% < E0
Time (ns)
Adjusted RF arrival timing
Electrons

40. Where is the drive beam? Phase coding recombination in DL DL CR
1.5 GHz DL CR D F
CTF2
CLEX
recombination in DL
Beam all the way through CLEX
Factor 4 recombination in CR

41. Where is the probe beam? CALIFES
Responsibility of IRFU (DAPNIA), CEA, Saclay
Dark current
Dark current K 10 20 25 25
beam dump
quadrupoles
15 MV/m
compression
17 MV/m
acceleration
17 MV/m
acceleration
CALIFES

42. The 2009 of CTF3 Sections in operation Linac PHIN CALIFES DL & Ring
30 GHz
TL2, TBL, TBTS (DB)
CALIFES
CLEX
stop
CALIFES
TL2
TBTS
TBL
Delay Loop
C. Ring

43. CTF3 commissioning status
DRIVE BEAM
MODEL VALIDATION
Gun instability disappeared
Linac commissioned
Delay loop factor 2 multiplication obtained
Vertical instability in the combiner ring eliminated: factor 4 multiplication achieved
TL2 commissioning started
Beam in PETS: power produced w and w/o recombination
MODEL VALIDATION
Gun instability disappeared
Linac commissioned
Delay loop factor 2 multiplication obtained
Vertical instability in the combiner ring eliminated: factor 4 multiplication achieved
TL2 commissioning started
Beam in PETS: power produced w and w/o recombination
IN PARALLEL
Steering algorithms (Linac and ring)
Bunch length measurements
Transient compensation
PROBE BEAM
First probe beam produced: CALIFES commissioning started
Ultimate the commissioning of the new lines (TL2+CLEX lines)
Put in operation DL and CR together to send ~30 A in PETS
First acceleration of the probe beam
CTF3 commissioning status

44. Extra slides

45. Delay loop principle double repetition frequency and current
parts of bunch train delayed in loop
RF deflector combines the bunches

46. RF injection in CR Cring = (n + ¼) l
combination factors up to 5 reachable in a ring
Cring = (n + ¼) l
injection line
septum
local
inner orbits
1st deflector
2nd deflector
1st turn lo
RF deflector
field
2nd
3rd
lo/4
4rd

47. DL 2 1
Factor 2 in the delay loop achieved 3

48. Wiggler currents correction
W/O
correction W
correction
CTF3 commissioning status

49. Tune measurements: the procedure
→ The measurement (oscilloscope + ”eyes”):
→ Fractional part of the tune determined from the Fourier transform of the H (V) signal in a BPM:
→ The sign is determined by the slope of the tune as a function of the quad strength variation
→ Compromise between oscillation amplitude and number of turns f
MAIN QL QR I H V
Nice reliability of the measurements
Time consuming (H and V measurements can take also half a day)
→ The model comparison (automatic):
→ Scan of the tunes as a function of the current in a quads family
→ Scan over the energy range

50. Error in the CR model
→ For the several corrections of the TL1/CR model the TL2 behavior predicted by the model (TL2 nominal optics)
sensibility.m

51. “Small” distributed errors (TL1+CR)
→ Random errors (gaussian mean = 0, s = 1% x INOM) in TL1 and half of CR
generateErrors.m

52. But in any case …
04/12/2008

53. CTF3 commissioning status

54. The 2009 goals of CTF3
30 GHz: Two structure test (TM02) + breakdown studies
CALIFES Beam characterization, beam to TBTS (most likely still reduced current)
Delay Loop Back in operation, retrieve combination x 2 (~ 7 A)
Combiner Ring Final optics checks, isochronicity, put together with DL (> 24 A)
TL2 Complete commissioning, bunch length control, > 20 A transported to users
TBTS PETS to nominal power/pulse length (15 A, recirculation)
Beam commissioning of probe beam line
First accelerating structure tests (one structure ? – CLIC G)
Two-beam studies (deceleration/acceleration), initial breakdown kicks studies
TBL PETS validation (100 MW, need > 20 A), beam line studies (2-3 PETS ?)
PHIN Beam characterization, reach ½ of nominal bunch charge ?
Others CDR studies in CRM, beam dynamics benchmarking, stability studies, control
of beam losses…

55. End