Linac Coherent Light Source LCLS Low Level RF

Linac Coherent Light Source (LCLS) Low Level RF System New RF System Commissioning Experience April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Safety Hazards in the LLRF system RF 1 k. W at 120 Hz at 5 u. S = 0. 6 Watts average, 2 Watt average amps at 2856 MHz, 60 W average amps at 476 MHz Hazards – RF Burns Mitigation – Avoid contact with center conductor of energized connectors. All employees working with LLRF systems are required to have the proper training. 110 VAC Connector Hazards - Shock Mitigation - Don’t touch conductors when plugging into outlet. All chassis are inspected by UL trained inspector (EEIP). April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

LCLS Layout P. Emma April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Scope of Work for Injector Turn-on 1 Linac Sector 0 RF Upgrade All 3 RF Chassis completed and Installed Control Module (IQPAU) needs modifications Sector 20 RF distribution system Phase and Amplitude Controllers (PAC) - Operational Phase and Amplitude Detectors (PAD) - Operational Phased Locked Oscillator – Use SPPS unit for Turn On LO Generator - Operational Multiplier – 476 MHz to 2856 MHz - Operational 4 distribution chassis - Operational Laser Phase Measurement – Needs some signal processing X-Band Reference – Chassis built, require testing and installation LLRF Control and Monitor System 1 k. W Solid State S-Band Amplifiers – 5 units PADs – 6 Klystron units in Fabrication PADs – Gun, L 0 A, L 0 B, L 1 S – Operational : Tcav, L 1 X in test PACs – Gun, L 0 A, L 0 B, L 1 S –Operational : TCav, L 1 X in test Beam Phase Cavity PAD in test Pill box cavity with 2 probes and 4 tuners – Complete April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Scope of Work for Injector Turn-on 2 LLRF VME control system Local feedback loops on RF phase and amplitude RF Gun Cell loop tested in lab at 360 Hz and in operation at 10 Hz L 1 -S loop tested in lab at 360 Hz and in operation at 30 Hz L 0 -A and L 0 -B loops tested in lab at 100 Hz Gun Tune temperature loop testing in progress Event system and timing triggers configured for accelerate and standby External interfaces Beam-synchronous acquisition LEM, SCP Correlation plots Channel Archiver – active for all installed channels Alarm Handler – initial layout done by J. Rock. Alarm limits TBD Global beam-based longitudinal feedback on L 0 -B and L 1 -S untested April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

SLAC Linac RF – New Control The new control system will tie in to the IPA Chassis with 1 k. W of drive power available. Reference will be from the existing phase reference line or the injector new RF reference Existing System April 16, 2007 LCLS LLRF FAC I and Q will be controlled with a 16 bit DAC running at 102 MHz. Waveforms to the DAC will be set in an FPGA through a microcontroller running EPICS on RTEMS. Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Processing RF Stations Gun – About 1 Week to Full Power L 0 A – About 2 Weeks to Full Power Most stations were and still are gassy by the klystron. April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Processing RF Stations L 0 B – About 2 weeks to Full Power April 16, 2007 LCLS LLRF FAC L 1 S – Easy 1 Week to Full Power Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Gun High Power RF Pulse Shaped by PAC L 0 A and L 0 B look similar Amplitude Waveform flat to +-2% Phase Waveform flat to +-2 Degrees Pulse width of 1. 2 u. S and >600 n. S of waveguide eliminates klystron power change due to reflected power and need for circulator. April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

L 1 S High Power RF SLED Pulse Shaped by PAC SLED Amplitude Waveform April 16, 2007 LCLS LLRF FAC Phase Waveform flat to +-2 Degrees Over fill time of structure Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Operational Units S-Band Reference System Laser SPAC Gun PAC L 0 -A PAC L 0 -B PAC L 1 -S PAC April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

PADs – Ready for Commissioning April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

Injector/L 1 Units Remaining to Commission TCav PAC Gun (done 4/12/07), L 0 -A, L 0 -B, L 1 -S, TCav PADs Klystron PADs Sector 0 IQPAU X-Band System VME based Feedbacks (Gun Cell Done) Diagnostic data analysis April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu

To Follow PAC software – more analysis in FPGA PAD software – evaluate speed Second network – to send waveforms out while running Switch to final network configuration putting embedded IOCs on private network Switch access to waveforms to use CA gateway VME – quantify CPU usage as each station is added April 16, 2007 LCLS LLRF FAC Ron Akre, Dayle Kotturi akre@slac. stanford. edu, dayle@slac. stanford. edu