david h. dowell injector rf design [email protected] november 3, 2004 1 lcls injector...
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David H. Dowell
Injector RF Design Review [email protected]
November 3, 20041
LCLS Injector RF Gun: Design, Fabrication & Tuning Plans
D. H. Dowell, SLACInjector RF Review: November 3, 2004
•Injector Requirements•Detail of Gun to Linac Region •Load Lock, Gun & Solenoid Description
–Some technical issues•RF Gun Status (design & procurement)•Current fabrication & procurement plans•Schedule•Gun tuning•Cooling system (preliminary)•Summary and Conclusions
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20042
Parameter Value Peak current 100 A Charge 0.1 – 1 nC Normalized transverse emittance projected/slice
1.2 / 1.0 m rms
Rate 120 Hz Energy 135 MeV Energy spread @ 135 MeV projected/slice
0.1 / 0.01 % rms
Gun laser timing stability 0.50 ps rms Booster mean rf phase stability 0.1 rms Charge stability 2.0 % rms Bunch length stability 5 % rms
LCLS Injector Performance Requirements:
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20043
Gun to Linac Region
PO
RC
UP
INE C
ATH
OD
E
HO
LDE
R
UH
V ALL META
L
GATE
VALV
ES
SPO
OLS
FRO
M VA
LVE
SEA
L
LON
G B
ELLOW
S
ASS
EMB
LY
TREA
TME
NT C
HAM
BE
R
VAC
UU
M P
UM
PS
Cathode Load Lock
RF Gun
Gun Solenoid
Gun Spectrometer
Linac Solenoid
L0-1Porcupine Cathode Clamp
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20044
Load Lock Conceptual Design
Stage for Cathode Insertion / Alignment
Treatment / Transfer Chamber
Cathode Holder
UHV All Metal Gate Valves
RF gun
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20045
S20 Alcove Floor PlanLaser Penetration
S20 Alcove includes aLoad Lock Room forInstalling & Processing Cathodes in Load Lock
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20046
Dual Feed RF Gun and Solenoid•Dual Feed/Racetrack Design Corrects RF Fields to Second Order•Solenoid Design Includes Both Dipole and Quadrupole Field Correctors
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20047
Gun Solenoid will have Dipole and Quadrupole Correction Coils
Multipole Amplitude
0
0.5
1
1.5
2
2.5
3
-0.2 -0.1 0 0.1 0.2
Longitudinal Position (m)
Mag
net
ic F
ield
Str
eng
th (
G)
Dipole 100
Quadrupole 100
Sextupole 100
Dipole 150
Quadrupole 150
Sextupole 150
Dipole 200
Quadrupole 200
Sextupole 200
Multipole Phase
-180
-135
-90
-45
0
45
90
135
180
-0.2 -0.1 0 0.1 0.2
Longitudinal Position (m)
Mag
net
ic F
ield
Ph
ase
(?)
Dipole 100
Quadrupole 100
Sextupole 100
Dipole 150
Quadrupole 150
Sextupole 150
Dipole 200
Quadruipole 200
Sextupole 200
Measurements of Gun Solenoid Multipole Fields
•Solenoid being designed with both dipole and quadrupole correcting coils
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20048
RF Gun Fabrication & Acquisition (Near Term)
April 2004: Released Request for Information to two vendorsApril 2004: Begin work on RF design for gunMay 2004: Vendors respond with budgetary quotes and schedules for engineering and fabrication of load lock and RF gun.August 2004: Technical meetings with vendors at SLACNow: Finalize RF designNow: Write Request for Proposal and send to vendors
Recent Decision: Load Lock prototype developed using SBIR with AES (Advanced Energy Systems)
David H. Dowell
Injector RF Design Review [email protected]
November 3, 20049
RF Gun Fabrication & Acquisition: Assumptions and Plans
Load Lock prototype developed using SBIR with AES (Advanced Energy Systems)Gun design should be compatible with future load lockSLAC does RF design for gun, provides design to vendorVendor engineers gun including thermal analysis and design of cooling systemVendor cold tests, fabricates and re-tests gunTechnical reviews at both SLAC and Vendor facilitySLAC participates with Vendor in RF and thermal tests of the gun and cooling systemVendor may participate in high power RF commissioning of gun at SLACVendor Delivers:
Hardware/Software:RF guncooling system including plumbing hardware used to test gun & cooling system computer control source code.
Documentation:All engineering drawings funded by this project especially those of gun and cooling systemWritten progress reports on contract progressWritten reports of rf and thermal tests. Reports should include raw data acquired during tests.
David H. Dowell
Injector RF Design Review [email protected]
November 3, 200410
Gun and L0-1 needed for installation:October 2006
LCLS Injector Schedule
David H. Dowell
Injector RF Design Review [email protected]
November 3, 200411
Machining, Tuning & Brazing the RF GunUnder-machine rf surfaces ~0.010”Clamp together and perform rf cold tests.Based on rf tests machine surfaces as requiredRe-do rf cold testsIterate rf tests and machining until gun on resonance and balanced.Perform time-domain and frequency-domain measurements of 0- and pi-modes, bead drop, needle pull, etc.Braze gun
Should a lower temperature braze be used to reduce softening of Cu?Use glidcop instead of Cu? (prefer Cu)Minimize number of brazes
Assemble gun with dual feed waveguidePerform time-domain and frequency-domain measurements of 0- and pi-modes, bead drop, needle pull, etc.Install on solenoid. Align rf and magnetic centerlines
David H. Dowell
Injector RF Design Review [email protected]
November 3, 200412
Balancing the Dual RF FeedsRequired tolerance between feeds (assume similar to L0-1 dual feed):
Phase <3 degree (s-band)Amplitude <2%
Machine to fitPhase shift per length of waveguide:
1deg-sband=278microns
Options for balancing feeds:Deform (squeeze) a section of the waveguidePhase shift due to temperature is small
For meter long waveguide section: 0.046deg-sband/deg-F
David H. Dowell
Injector RF Design Review [email protected]
November 3, 200413
Dual Feed Using Standard Waveguide Components
David H. Dowell
Injector RF Design Review [email protected]
November 3, 200414
RF Gun Cooling System
Cooling TowerWater
ChillerNear Gun
TemperatureController
RF Gun
Temp Meas
Left Waveguide Feed
Temp Monitor
Right Waveguide Feed
Waveguide Water
David H. Dowell
Injector RF Design Review [email protected]
November 3, 200415
Summary and Conclusions
Reviewed Load Lock (LL), gun and gun solenoid requirements and constraintsGun design compatible with future LLGun & solenoid designed as a single assembly for easy replacement with future gunS20 Alcove includes a Load Lock Room for cathode developmentBuild prototype LL with SBIR with AES
Present gun fabrication plan:SLAC designs gun RF geometryVendor does thermal & mechanical engineeringVendor fabricates and cold tests gunProgress and technical reviews at SLAC and Vendor facilityVendor delivers gun, documentation
Gun needed by Oct 2006 for installationDescribed machining, tuning & brazing processControl of amplitude & phase between the dual feedsProposed cooling system for gun and dual feed waveguide