ILC Polarized Electron Source Baseline Technical Review October

ILC Polarized Electron Source Baseline Technical Review October, 2011 A. Brachmann, J. C. Sheppard, F. Zhou SLAC DESY October 24 -27, 2011 Page 1

ILC Electron Beams TABLE 1). Major parameters of the ILC high-current high-polarization electron source. Parameters ILC RDR ILC 500 Ge. V Ref. ILC Te. V Straw Particles Per Microbunch 3 x 1010 Number Of Microbunch 2625 1312 2280 1 ns [~ps bunched] 356 ns 670 ns 356 ns Bunching Frequency 2. 8 MHz 1. 35 MHz 2. 8 MHz Width Of Macropulse 1 ms Macropulse Repetition Rate 5 Hz (10 Hz) 5 Hz (10 Hz? ) Charge Per Macropulse 8000 n. C 4000 n. C 7000 n. C Normalized Emittance, source 0. 1 m-rad Normalized Emittance, damped 1 x 10 -5 / 4 x 10 -8 m-rad >80% Width Of Microbunch Time Between Microbunches Polarization, electrons DESY October 24 -27, 2011 Page 2

ILC Electron Beams Discussed at Baseline Assessment Workshop at SLAC January 18, 2011 Discussed at ILCWS 2011 in Granada, Spain in September, 2011 DESY October 24 -27, 2011 Page 3

MCR Questions: AD&I October 12, 2011 Electron Source (John Sheppard) There a handful of issues (none major) Changing bunching frequency to 325 MHz Do we have enough cooling in the NC RF to run at 10 Hz? Are the utilities properly reflected in the 10 Hz parameters? Layout of the linac to ring transport line Marc: what about underground space requirements? John: CFS people have asked for a layout of the beamline and they will then lay out the tunnel around it. DESY October 24 -27, 2011 Page 4

The Baseline ILC Electron Source 325 Electron source provides polarized electron beam and consists of all systems from source laser to 5 Ge. V injection to damping rings. (2011 layout: 325 MHz SHB) DESY October 24 -27, 2011 Page 5

Electron Beams, Cathode Status (RDR) Baseline design: strained layer superlattice Ga. As/Ga. As. P Polarization ~ 85 - 90 % , QE 1% maximum, 0. 3 -0. 5% routinely High gradient p-doping increases QE and reduces surface charge limit: 5 x 1019 cm-3 5 x 1017 cm-3 DESY October 24 -27, 2011 Page 6

Jefferson Lab Polarized Electron Gun 200 k. V (in development) Jlab DESY October 24 -27, 2011 Page 7

SLAC Polarized Electron Gun, GTL (~1989 back-up) SLAC DESY October 24 -27, 2011 Page 8

Parameter comparison Parameter RDR SB 2009 Number of bunches 2625 1312 Repetition rate of macro bunch 5 Hz Bunch Spacing 356 ns 670 ns Beam Current 9. 0 m. A 4. 8 m. A

ILC Electron Beams, Changes from RDR 1300 Bunches—low power option—easier on laser 325 MHz SHB Bunchers—timing/fill pattern options—power sources(? Not an issue? ) 10 Hz—low energy option—NC&SC ops at 10 Hz, CFS increase ELTR Optics—Central Region—parts count DESY October 24 -27, 2011 Page 10

1300 bunches: Laser Physics Parameter (Ti: Sapphire) p 0 = p Value 3. 5*10 -6 s 532 nm 3 MHz 100 k. Hz 50 µm l 1 cm Pp 40 W ηp 0. 9 Conclusion: Bunch spacing of 670 ns results in more amplifier pumping compared to 356 ns.

1300 bunches: Beam Dumps Keep RDR Dump Power Capability: 1. 5 times expected beam power at 2625 bunches, 5 Hz Works for 1300 bunches at 10 Hz

325 MHz SHB DESY October 24 -27, 2011 Page 13

325 MHz SHB DESY October 24 -27, 2011 Page 14

325 MHz SHB Tesla-2001 -22 -2 w’V’ = w 0 V 0 Scaled SHB parameters Cavity # F MHz Voltage k. V Rs MW Q 0 P W tf ms Vb k. V 1 325 13 5. 1 2. 0. 104 ? ? ? 2 325 59 5. 1 2. 0. 104 ? ? ? DESY October 24 -27, 2011 Page 15

10 Hz NC rf: Heat Load P/m = Tp. Pklyf(1 -e(-2 ))/L P 10 Hz 17 k. W/m at L-Band Pslc = 3 k. W/m at S-band, DT = 4 o. F Expect DT to scale at least as well as 1/f DT 10 o. F…. needs to be checked Can double up on modulators and klystrons as necessary, should only need larger charging supplies DESY October 24 -27, 2011 Page 16

10 Hz SC rf Have not considered whether or not 10 Hz operation of electron source SC rf is a problem other than additional power load. Assume that the Main Linac solves this problem DESY October 24 -27, 2011 Page 17

10 Hz CFS: Presently 5 Hz Granada September 28, 2011 Page 18

10 Hz CFS, cont’d At 5 Hz, Electron Source power load is estimated as 4. 3 MW as per Emil Huedem (RDR C. Corvin ~2007) This is ~2% of ILC Total Going to 10 Hz increases Electron Source power load to 8. 6 MW This is ~3% of ILC Total (assume electron main linac doubles power requirment) So, need to increase Electron Source power load to 8. 6 MW DESY October 24 -27, 2011 Page 19

ELTR: PLTR Floor Map (WL and WG) Granada September 28, 2011 Page 20

ELTR Parasiting off PLTR Need to count Parts and Update Inventory & costs May have small detail in regards to how SC rf module envelopes have changed since RDR…. a very minor optics deck, coordinate layout (not sure if this is real, not sure how minor if real (centimeters or meters? ) DESY October 24 -27, 2011 Page 21

MCR Questions, cont’d e- source 1 10 Hz parameters issues 2 Changing bunching frequency to 325 MHz 3 Access and underground space requirements Needs review a formality Needs specification Primarily a CFS requirements question Linked to service tunnel, which solves this problem. Service tunnel criteria to be compiled and reviewed. e- Source 1. 10 Hz parameters issues Needs review— check nc rf heat scaling w/ expert Primarily a CFS requirements question 2. Changing bunching frequency to 325 MHz a formality– done for now 3. Access and underground space requirements Needs specification– not sure who does this Linked to service tunnel, which solves this problem. Service tunnel criteria to be compiled and reviewed. DESY October 24 -27, 2011 Page 22

EDMS? e- Source Need to jump onto EDMS and Costing Will model EDMS documentation on e+ documentation as much as possible. DESY October 24 -27, 2011 Page 23

Additional and Backup Slides

Status of laser system development Two similar laser systems are being developed: 1. 2. SLAC design SBIR laser system (KM Labs) Both systems share similar challenges cw amplifier pump lasers KM Labs system has been operational at 1. 5 MHz at KM Labs facility inspected in October 2010 Delivered to SLAC in December 2010 KM Labs and SLAC systems are now in the process of restarting installation here at SLAC’s ILC ITF

Gun development at Jlab’s Inverted gun design Inverted Insulator Cathode Anode Feedthrough Anode NEGs and Ground Screen conditioned to 150 k. V without observed field emission

ILC Electron Beams, Critical Issues 3 MHz Laser System (in development) Cathode Demonstration (probably okay) NC Capture Structure demonstrated (2007? ) SLAC Laser and Jlab Gun Granada September 28, 2011 Page 27

ILC Electron Beams, Issues and Questions Laser Repetition Rate is ~3 MHz, limited by final stage amplifier pump scheme Need to do some thinking if can bunch at 325 MHz (likely just fine) What is ILC bunch spacing/bunch frequency (~3 MHz) What is ILC pulse length? (~1 ms) Need to worry a little about NC accelerator cooling at 10 Hz Granada September 28, 2011 Page 28

ILC Electron Beams, Laser Development Granada September 28, 2011 Page 29

ILC Electron Beams, Laser Development 76 MHz fs mode locked cw oscillator fs-to-ns pulse stretcher/shaper 3 MHz Pockels cell pulse selection Pair of 18 W cw green pump lasers (July, 2010) Cryocooled Ti: Al 2 O 3 gain cell Regen amp in development (Spring, 2012) Granada September 28, 2011 Page 30

ILC Electron Beams, Laser Development 3 MHz Regen Amp Cryocooled Ti: Al 2 O 3 gain cell Granada September 28, 2011 Page 31

KM Labs system installation

Test Cave issues at Jlab Renovation of Test Cave building at Jlab beginning of FY 2012 to early in FY 2013 Have delayed Test at Jlab Another issue is the lack of time resolution for polarization measurements. Priority issues for ILC (lab resources, facilities support for ILC R&D, manpower, etc. )

R&D Summary Source laser R&D and Gun R&D are progressing at SLAC and Jlab. Beam Test may take place at SLAC, at least for BAW parameters (man power issues). Beam tests at Jlab are delayed. Still looking to demonstrate 3 MHz laser at SLAC