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C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20051
Injector PhysicsC.Limborg-Deprey
GTL final designWakefield budgetFinal Modifications Commissioning Readiness
ScheduleFeedback systems
An example of tuning procedureSteering in L0a
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20052
Injector
PORCU
PINE CATHODE
HOLDE
R
UHV A
LL METAL
GATE VALVES
SPOOLS FRO
M VALVE
SEAL
LONG B
ELLOWS
ASSEM
BLY
TREATMEN
T CHAM
BER
VACUU
M PUMPS
Gun installation Nov. 2006
Gun Region July 2006
Accel Region June 2006
Heater Region June 2006
Wall Region October 2005
Waveguide October 2005
Injection Region Aug-Nov 2006
Spect Region Aug-Nov 2006
Injector Commissioning Start December 2006
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20054
GTL Design
Normal incidenceMirror size (14mm x 10 mm)
No second Valve in GTL All wakefield computed
(see next slides)Diagnostics units finalized
accommodate 20 mm screens wakefield mitigation
Gun Solenoid moved as close as possible to cathode
Bucking Coil added (PRD written)cancels the 55 Gauss Bz field on cathode
Compatibility with gun bake + cathode removal
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20055
GTL Design
Pending issues<1.05 permeability of VV01
Impact on Bsolenoid falling edge to be measured
Choice of material for injector mirrorOptical path for CRG1 lightFinalization of GTL BPMs to meet 20 m resolutionAlignment laser specificationsFinal GTL design review next week Courtesy J.Langton
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20056
Wakefield Budget
projected <1.2 mm-mradwith no error simulations show 1.0 mm-mradStability of electro- magnetic components to meet less than 10% increase<10 % increased from total wakefield effects over the whole beamline
GTL area is critical region
Injection mirror with 1mm beam offset
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20057
Case d L Wake
(1) 6 mm 10 mm 0.247 V/pC on axis
(2) 6 mm 10 mm 146 V/pC/m
(3) 6mm 15 mm 171 V/pC/m
(1) (2) (3)
MAFIA Simulations, Courtesy Cho-Kuen Ng
Wakefield from Injection Mirror
d
L
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20058
Wakefield Mitigation in GTL
Pumping slots 0.24 V/pC/m per unit 3 units at 0.6 m3 units at 1.2 m Negligible emittance growth
Combined Diagnostics chambers Wakefield Mitigated ~small gaps
Courtesy J.Langton
Courtesy Cho-Kuen Ng
Pumping slot
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 20059
Wakefield Mitigation in GTL
Spectrometer bend chamberWakefield mitigation movable plug
Eliminates any wakefield Small gap
BellowsSleeve on each 7Small step transition instead of 25V/pC/m
]//[34.433
mCVga
cZk z
oloss
Gaps1mm gap ~ 3V/pC/m Beam to
Spectrometer
Straight beam
Courtesy J.Langton
Plug out
Sleeve
Bellows
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200510
oo
2
2
1~
Wakefield in Radiation Stopper
Radiation Stopper not an issueLCLS-TN-05-15
"Wakefield Calculations for Radiation Stopper 1 (RST1)“
Wrms < 0.077V/pC on axis
/ < 0.1% due to small =1.5 m
MAFIA computations
Courtesy Cho-Kuen Ng
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200511
Final changes in Accelerator Region
Courtesy P.Stephens
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200512
Beamline Modifications
L0a moved downstream by 8 cmOk with emittance compensation
Solenoid 2 reduced to 20 cm effective length magnet (Req. sent out)
higher Bfield for same focal length
higher Bfield is not an issue
Suppressed one out of 2 BPMs in L0a-L0b drift4 inch Phase monitor fits inValve moved from L0a entrance to L0a-L0b drift
Mu-shield metal wrapped around all possible locationPRD 1.1-009Unfortunately not possible in GTL
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200513
Diagnostics
Critical decisionsSpecifications for screens and resolution finalized (PRD out)CR material: 1mm thick, quartz, to be replaced with aerogel laterOTR cameras orientation to increase depth of fieldStreak camera orderedChoice of CCD cameras finalized
Remaining issuesOptical path for CRG1 light2nd pick-up on toroid for BCS Alignment laser spec. to be finalized Finalization (Resolution) of BPM design for large aperture pipe
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200514
Commissioning Schedule Discussed every 5th week with LCLS physicists/operators group
To be incorporated into large *.mpp document for linksDiscussed weekly inside Injector group
(Bong, Dowell, Limborg, Loos, Schmerge …)Based on 2 shifts per dayResource loading to be refined
2 physicists per shift + 1 control person + 1 operator guests
Meeting will evolve in high level application discussionSchedule Outline
Starts with RF Gun cold and hot test (summer 06)First beam at 135MeV dump (Nov.22-06 Dec.06)8 months of characterization and optimization
Deliver most stable beam for acceptable charge for BC1 commissioning at end of June07
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200516
Commissioning Readiness
Pending issuesHot test schedule
Finalize start date, detailed schedule
Feedback Systems
Calibrations procedure Magnetic calibration procedure drafted
Screen calibration procedure
High Level Applications
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200517
High Level Applications
Cathode characterization (QE, uniformity, Thermal emittance)Steering in L0aLongitudinal phase space measurements at BXG Bunch length measurement with transverse RF deflector(s)Emittance meas. (multi-wire, multi-OTR, quad-scan, slice)Power-steering through beamlines, with corrector weightsDifference orbit fitting, including internal kickLongitudinal phase space measurement at BXS Tomography (Longitudinal and Transverse)…
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200518
Feedback SystemsPointing Stability (see Laser)
ToleranceSlow (f<1Hz) : <200 m (or slice emittance degraded)Fast (1Hz<f<120 Hz): <10 m (1% of “10% x,undulator budget”)
Slow feedback : Sensor/ actuatorVirtual cathode / mirrorsStatus : preliminary tests at bldg 407
Fast stability Design constraint (Gun + injection mirror + vacuum chamber “rigidly” linked to optical launch table ,i.e. less than 10m fast motion )
Charge Stability (see Laser)Tolerance
Fast (shot-to shot) < 2%rmsSensor/Actuator
first toroid IM01/ polarizer
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200519
Feedback Systems
Timing StabilityTolerance
Fast stability (120Hz),laser phase w.r.t master clock < 0.5 ps rms
feedback system sensor : phase monitor signal actuator: locking electronics from Thales system
Slow stability (<1Hz), laser phase w.r.t gun phase < +/-3 ps to maintain emittance within 5% of optimal
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200520
Steering in L0a
SolenoidSC0 SC1 SC2
BPM2 BPM3 BPM5Gun L0a
Solenoid mispositioning 250 m, 250 rad
Earth Magnetic field 2mrad/m vert.
No space for mu-metal shielding in GTLBy ~ 0.35 GBx ~ 0.12 G
Offset as large as 3mm without steering
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200521
Simulations of steering
SolenoidSC0 SC1 SC2
BPM2 BPM3 BPM5Gun L0a
Procedure
L0a solenoid offOrthogonal knobs at SC0 SC0 and SC1 adjusted to steer in L0a
Scaling of SC0 orthogonal knobs with solenoid to be implemented in software when
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200522
Conclusions
GTL Design finalized
L0a-L0b space issue solved
“Laser Heater” region to be detailed
Commissioning schedule under completion
Feedback systems under completion
High Level Applications to be written
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200523
Response to the April FAC Recommendations
Wakefield in Gun Large Energy spread in gun identified to be related to 0-mode
ACD group will perform more simulations
3D-ellipsoidal laser pulses Presented at major conferences, in particular at FEL05 with good interest shown from many laser experts
C.Limborg-Deprey
LCLS FAC , Oct 2005 [email protected]
Oct 27th 200525
Hot test scheduleObjectives
Task1 : RF ConditioningTask2 : Verification of thermal design (f vs Power, f vs T)Task3 : Close LLRF feedback loop
LLRF feedback loop can only be closed if availability of Chiller, Instrumentation of detection of phase from reflected power signal, Drive Amplifier
Four scenarios discussed
Klystron lab. (PEP bunker)
Aug. 06
S20
July 06
S20
Sep 06
S20
Dec06
+ Early start, possible retrofit
No impact on S20 work
Early start
No special PPS
Single installation
No (-) from previous 2
All (+) from previous 2
“Special PPS” forced in (*)
Early commissioning
All systems ready
No special PPS
No impact on S20 work
- Dvt Local Control
Shielding work , add parts
Long WG to be found
Task 3 cannot be completed
PPS finished unlikely
Access Timing cables
Impact laser work
Task 3 cannot be completed
“Special PPS” difficult to obtain
High Technical risk
Delays Commissioning with beam
(*) “Special PPS” == run klystron + e beam to spectrometer during linac downtime
