Tuning Techniques And Operator Diagnostics for FACET at SLAC National Accelerator Laboratory Chris Melton SLAC Accelerator Operations
FACET Tuning And Diagnostics What is FACET? FACET Performance Challenges Operations Solutions FACET Future 2
What is FACET? Facility for Advanced Accelerator Experimental Tests Design Criteria Facility overview Scientific mission 3
FACET Beamline Overview 4
FACET W Chicane Beamline e- from Linac Beam to User Experiments 5
FACET Experiment Beamline e- from W chicane 6
FACET User Experiment Facilities e- from W chicane 7
FACET Design Criteria FACET is designed to deliver high energy, high peak current, short bunch length electrons and positrons with low transverse emittance to user experiments. The Ideal Beam 23 GeV e- and e+ beams 30Hz pulses 3.2nC bunches 20 ka peak currents (I pk ) 20 m bunch length ( z ) 20 m x 20 m spot size ( x,y ) 8
FACET Scientific Mission New research frontiers require larger, more expensive accelerators New accelerating methods can reach higher energies in shorter distances These methods leverage plasma wakes in dielectric & metallic structures FACET was an ideal test facility for these new techniques due to The high charge of SLAC Linac beams The high compression made possible by SLAC beamlines High historical demand for electron / positron beams from the SLAC Linac Success of the SLAC Final Focus Test Beam (FFTB) plasma experiments FACET will serve the scientific community as a high energy physics user facility for the exploration of novel methods of beam acceleration, related beam physics, and development of related diagnostics, with specific applications to materials, biological, energy, and plasma sciences. 9
FACET Science Plasma Wakefield Acceleration How FACET generates high gradient acceleration with low energy spread: Send a bunch of electrons through Lithium (2011) or Rubidium (2012) plasma This drive bunch creates a ~ 50GeV/m acceleration gradient in the plasma A witness bunch then travels through the plasma and is accelerated 10
FACET Performance First beam to FACET dump on June 23, 2011 11
What To Characterize and Tune? How? Primary beam properties of interest Charge Position Transverse Beam Size Transverse Emittance Longitudinal Beam Size Tools for measurement Toroid Charge Monitors Beam Position Monitors Profile Monitors (YAG, OTR) Wire Scanners Transition Radiation Monitors If it were only that simple 12
Diagnostic Challenges - Linac Few measurements of bunch length ( z ). Accuracy? Emittance ( x,y ) and beam size ( x,y ) measurements slow Lack of efficient and robust beta matching tools No dispersion characterization tools until end of 2012 run E z x,y x,y z x,y x,y 13
Diagnostic Challenges Chicane & IP E Densely installed magnets and experiment stations - little room for BPMs, Wires, and Profile Monitors Few robust and convenient beam diagnostics after Linac Vertical W Chicane dispersion not yet understood Beam Based Alignment very difficult (sextupole movers) Optical Transition Radiation damage at peak compression Beam waist location often unknown z x,y x,y 14
SLAC Operations Finding What Works SLAC Operators start building software early Proficiency in Matlab and EPICS is encouraged Collaborative environment encourages revisions Google Model: Build often; Failure is ok! Operators have standardized a display format High contrast allows readability from across the room Summary displays for subsystems by geography Graphic overlays draw eye toward meaningful data Information density balanced against interactivity 15
SLAC Main Control Room Can we do better? 16 16
Yes! 17
Including Klystron Displays 18
Console Tuning and Diagnostics FACET uses a hybrid control system: OpenVMS and EPICS 19
Console Tuning and Diagnostics Example: Investigating a Beam Containment System (BCS) Alarm 20
Console Tuning and Diagnostics Example: Investigating a Beam Containment System (BCS) Alarm 21
Console Tuning and Diagnostics Console driven high level tuning and diagnostic information 22
Console Tuning and Diagnostics Example: Measuring transverse beam size 23
Console Tuning and Diagnostics Example: Measuring transverse beam size 24
New Tools For Better Performance 25
What s Next For FACET? X-band Transverse Deflection Cavity Better bunch length diagnostics Commissioning started end of 2012 run Testing will continue during 2013 run 26
What s Next For FACET? FACET-II? FACET-II would be an R&D accelerator using the first 1/3 of the Linac Early FACET-II would be about January 2018 including construction Upstream of LCLS-II, which poses diagnostic constraints - Final focus energy feedbacks will need different BPMs - Space and budget constraints restrict profile monitors and wire scans - 27
Questions? 28