RF-Gun for Phase-II RF Gun workshop @ 10, June, 2016

Schedule Last RF-Gun review Done On going Reconfigure thermal gun for positron generation Step by step RF-Gun RF ageing. Done SuperKEKB injection using stabilized existing undergroud laser (25Hz) New laser system in 3-2 and A-1 ground laser room Increase stability & pulse energy from fiber laser Simplify the laser system (Nd/Yb Regenerative amplifier) On going Third RF-Gun (nomal laser injection / cavity modification / cathode change) Simple Nd amplifier for Phase-I & II stable injection Following the RF-Gun reviewer’s comments (Postponed the pulse shaping until Phase-III ) 10 ps gaussian is enough for Phase-I (1nC) & II (2nC), postponed the pulse shaping until Phase-III

RF-Gun for Phase-II RF-Gun (Natsui) Cathode (Sato) Backup SC-QTW is already available (RF ageing was done) New CDS-type RF-Gun is under fabrication Second RF-Gun will be installed in this summer shutdown with 90-degree arc section. Cathode (Sato) Better QE uniformity : Ir7Ce2

Second RF gun on the 45 degree line Normal laser injection RF conditining at 6-1 is on going before installation. Studies on CDS-type RF-Gun cavity. Normal laser injection. Changeable cathode including thermal assist IrCe. Angled laser injection

Choke mode cathode rod fix Breakdown at cathode rod is one of the problem. New gun will be choke structure. Dummy cathode rod is used. No cathode, all copper.

Simple cavity RF gun is developed for test Cut Disk Structure (CDS)

Laser for Phase-II Simplification Stabilization Higher power output 10.38 MHz oscillator (higher pulse energy / no pulse picker / lower ASE) Nd:YAG Regenerative amplifier Stabilization Pointing feedback system Commercial oscillator Vacuum optical transmission line Reduction of environmental noise ( casing etc,.) Higher power output Nd:YAG disk stack with 885 nm pump

Yb fiber and Nd/Yb solid laser system on the A-1 ground Yb fiber part (already installed) Repetition frequency 114.24MHz Wavelength selection 1030nm & 1064nm Repetition frequency 10MHz 1064nm oscillator (ANDi type) Grating stretcher (Transmission) SOA pulse picker Yb single mode fiber amp Menlo 1030nm oscillator FBG FBG Yb-doped double clad fiber amp ASE rejection grating pair 1030nm oscillator (ANDi type) 1064nm 1030nm 1030nm oscillator (10.38 MHz) EO pulse picker Yb:YAG Thin disk regenerative amplifier 1064nm Nd:YAG regenerative amplifier Cryogenic Yb:YAG Thin disk main amplifier Nd:YAG main amplifier Nd:YAG for Phase-II Output(1064nm) Output(1030nm) Yb:YAG for Phase-III 96ns Delay => Combine => SHG => FHG

Nd:YAG regenerative amplifier

For Phase-III New 90-deg beamline Laser Cathode (Sato) Detailed bunch shape monitor (RF-Deflector) Bunch shaping by slit at 90-deg arc Laser Chirp pulse amplification with pulse shaping Yb:YAG regenerative amplifier + Cryogenic Yb:YAG main amplifier Cathode (Sato) QE improvement using single crystal IrCe cathode Thermal assist for higher QE & cathode cleaning