1. Polarized e- Source Design and R&D 10/24/05
Laser Development
Photocathode R&D
Proposed SBIR’s
Simulations

2. Laser Development Near term plan: (cost ~ 20 K$)
Use 76 MHz mode-locked Ti:Sapphire (Mira 900) as pulse train source
(oscillator and pump need to be relocated to new lab)
Pulse train slicing with fast pulser/pockel’s cell combination
Pulser: 3 MHz burst mode ( 1-2 ms bursts at 5 Hz)
Pockel’s cell: Cleveland Crystal 3 crystal BBO cell
(cost ~ 20 K$)
Work will start upon completion of B006 roof and HVAC work; (anticipated near the end of November)
Laser Development is also subject of SBIR project

3. Photocathode R&D
SVT SBIR Phase I to investigate InGaP-GaAs strained superlattice
First sample expected soon
SAXET STTR Phase II to study bias effect on QE and polarization.
Observe bias effect on QE, polarization next.
InAlGaAs-GaAs strained superlattice
Observe 84% peak polarization

4. Bias effect on QE

5. Proposed SBIR’s (Submission deadline 12/02/05)
Laser Development
Discussions with KM Labs to submit SBIR phase I proposal to develop source laser that can be used with RF gun or DC gun based source
KM Labs is a small laser company with expertise in Ti:Sapphire oscillators and amplifiers (Boulder CO).
Experienced with SBIR business (e.g. SPPS, LCLS)
RF-Gun development
Development of L-Band RF-Gun for a polarized source
Small Business partner is SAXET (Greg Mullholan) – expertise in vacuum work
1.6 cell L-band vs. HOM structure  HOM preferable geometry for pumping
RF testing with L-band RF test stand at Fermilab or SLAC’s ESB

6. RF-Gun structures and pumping requirements
Conductance and pressure differential at cathode for various
S-band gun designs with 2 assumed outgassing rates for Cu.
1.6 cell / HOM
Gun Design
Conductance
DP (Torr) for:
(l/s)
10-11 Torr-l/s cm-2
10-12 Torr-l/s cm-2
BNL 1.6-cell SB
with conventional
Pumping
3.7
1.610-9
1.610-10
with sieve 12
510-10
510-11
PWT (2/2+7 to 10
cells) 28
210-10
210-11
PWT (1.5 cells) 50
1.210-10
1.210-11
HOM 75
810-11
810-12
Details: RF Guns for Generation of Polarized Electron Beams
J. E. Clendenin, A. Brachmann, D. H. Dowell, E. L. Garwin, K. Ioakeimidi, R. E. Kirby,
T. Maruyama, C. Y. Prescott (SLAC), R. Prepost (U. Wisconsin)
Nanobeam 2005

7. Simulations Original work by A. Curtoni & Jablonka TESLA 2001-22(2):
Study of the TESLA preaccelerator for the polarised electron beam, TESLA
Extension of work for increased Gun HV (DC-gun)
Started working on our own simulations using various beam simulation tools (E-gun, GPT, …)

8. Simulations – preliminary
What gun voltage do we need to simplify pre-buncher ?
SLC polarized
gun geometry
2 cm cathode diameter
120 – 350 kV
Include Space Charge

9. Gun HV vs. buncher frequency
Gun HV [kV]
Peak Current [A]
ILC design charge [nC]
Required bunch length for ILC design charge [ps]
Required Buncher frequency[1] [MHz]
120
7.8
3.2
412
606
6.4
826
303
160
12.0
536
466
200
16.8
384
652
250
23.4
275
910
300
30.7
209
1200
350
38.6
165
1500
* To match bunch length in t/4 period of buncher frequency