1. Beam plan at STF phase1 12/6/2005 TTC-WG3 H. Hayano STF phase1 1st step : DC-gun + photo-cathode (2006) quick beam source( DC gun exist), no pre-acceleration, no buncher, but high density beam -> big space charge, bad transmission. 2nd step : RF-gun + photo-cathode (2007) similar to TTF, but heavy-load of laser development* RF-gun: easy extension of S-band RF-gun of ATF. *Laser development will be done continuously from step 1 to step 2. ** Why two step?: limited budget and man power, however need some beam to confirm cavity gradient in initial stage.

2. Reason of Beam at STF To develop following performance & technologies; 1. Cavity gradient, 2. LLRF control for beam loaded cavities, 3. HOM studies for TESLA type and LL type, 4. Instrumentation (BPM, BSM) development, 5. Laser development for ILC beam generation, later, want to expand them to ILC Pol e- generation study*. (* Pol e- : by Nagoya-univ. and KEK collaboration)

3. Acceleration field on axis for simulation Cs-Te photo-cathode solenoid Plan of DC-gun Existing photo-cathode DC gun (Step 1)

4. Full ILC Charge 3.2nC 10ps bunch length 200keV energy ~50% transmission Beam transmission simulation

5. 1/10 Charge 0.32nC 10ps bunch length 200keV energy ~80% transmission

6. 1/100 Charge 0.032nC 10ps bunch length 200keV energy 100% transmission

7. Required Laser System 10mA average current within a macro-pulse require 4.2W average laser power with the following conditions; –CsTe photo-cathode –266nm laser energy –1% QE

8. Laser System (2) Mode-lock oscillator can make a laser pulse train with several 100 MHz frequency. Fundamental wave length is not in UV. Need FHG for Nd:YLF and THG for Ti:Sa. HG crystal however can not be operated in such high average laser power. Start with lower average power (~100mW), upgrade to the higher power. (OPCPA?)

9. Conclusion of simulation and available laser, 1/100 charge : 100% transmission in case of reduced field of #1cavity (~40% of 35MV/m) to increase beam loading with this small charge, need 100 times narrower bunch spacing and 100 times bigger number of bunch. However initial Laser system power will be ~2% of full specification, Beam loading experiment will be the next priority study. * Also need special treatment of reduced field for the first cavity.