ron akre, dayle kotturi lcls llrf [email protected]@slac.stanford.edu,...
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Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Linac Coherent Light Source (LCLS)
Low Level RF System
New RF System Commissioning Experience
April 16, 2007
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Safety
Hazards in the LLRF systemRF 1kW at 120Hz at 5uS = 0.6 Watts average, 2 Watt average amps at 2856MHz, 60W average amps at 476MHz
Hazards – RF BurnsMitigation – Avoid contact with center conductor of energized connectors. All employees working with LLRF systems are required to have the proper training.
110VAC ConnectorHazards - Shock Mitigation - Don’t touch conductors when plugging into outlet.All chassis are inspected by UL trained inspector (EEIP).
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
LCLS Layout
P. Emma
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Scope of Work for Injector Turn-on 1Linac Sector 0 RF Upgrade
All 3 RF Chassis completed and InstalledControl Module (IQPAU) needs modifications
Sector 20 RF distribution system - Phase and Amplitude Controllers (PAC) - OperationalPhase and Amplitude Detectors (PAD) - OperationalPhased Locked Oscillator – Use SPPS unit for Turn OnLO Generator - OperationalMultiplier – 476MHz to 2856MHz - Operational4 distribution chassis - OperationalLaser Phase Measurement – Needs some signal processingX-Band Reference – Chassis built, require testing and installation
LLRF Control and Monitor System1 kW Solid State S-Band Amplifiers – 5 unitsPADs – 6 Klystron units in FabricationPADs – Gun, L0A, L0B, L1S – Operational : Tcav, L1X in testPACs – Gun, L0A, L0B, L1S –Operational : TCav, L1X in test
Beam Phase CavityPAD in testPill box cavity with 2 probes and 4 tuners – Complete
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Scope of Work for Injector Turn-on 2LLRF 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 L1-S loop tested in lab at 360 Hz and in operation at 30 HzL0-A and L0-B loops tested in lab at 100 Hz
Gun Tune temperature loop testing in progressEvent system and timing triggers configured for accelerate and standby
External interfacesBeam-synchronous acquisition LEM, SCP Correlation plotsChannel Archiver – active for all installed channelsAlarm Handler – initial layout done by J. Rock. Alarm limits TBDGlobal beam-based longitudinal feedback on L0-B and L1-S - untested
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
SLAC Linac RF – New ControlThe new control system will tie in to the IPA Chassis with 1kW of drive power available. Reference will be from the existing phase reference line or the injector new RF reference
I and Q will be controlled with a 16bit DAC running at 102MHz. Waveforms to the DAC will be set in an FPGA through a microcontroller running EPICS on RTEMS.
Existing System Accelerator
Klystron
Next Sector
MDL 476MHz
SubBooster
6 X2856MHz
Sub Drive Line
High PowerPhase ShifterAttenuator
SLED
Phase &AmplitudeDetector
ExistingPhaseReferenceLine
-45dB200MW
3kW
20mW
1W1mW
To NextKlystron
I
RF LO
Q
1
2
3
4
IQ Modulator
1kW Amp2856MHz
IPA
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Processing RF Stations
Gun – About 1 Week to Full Power L0A – About 2 Weeks to Full Power
Most stations were and still are gassy by the klystron.
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Processing RF Stations
L0B – About 2 weeks to Full Power L1S – Easy 1 Week to Full Power
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Gun High Power RF Pulse Shaped by PACL0A and L0B look similar
Amplitude Waveform flat to +-2% Phase Waveform flat to +-2 DegreesPulse width of 1.2uS and >600nS of waveguide eliminates klystron power change due to reflected power and need for circulator.
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
L1S High Power RF SLED Pulse Shaped by PAC
SLED Amplitude Waveform Phase Waveform flat to +-2 DegreesOver fill time of structure
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Operational Units
S-Band Reference System
Laser SPAC
Gun PAC
L0-A PAC
L0-B PAC
L1-S PAC
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
PADs – Ready for Commissioning
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
Injector/L1 Units Remaining to Commission
TCav PAC
Gun (done 4/12/07), L0-A, L0-B, L1-S, TCav PADs
Klystron PADs
Sector 0 IQPAU
X-Band System
VME based Feedbacks (Gun Cell Done)
Diagnostic data analysis
Ron Akre, Dayle Kotturi
LCLS LLRF FAC [email protected], [email protected]
April 16, 2007
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