Lasers and Ultra-precise Timing

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Lasers and Ultra-precise Timing

• Injector Laser and Commissioning
• Injector Laser review
• Commissioning Experience
• Updates to transport and controls
• Hand-off to operations
• Ultra-precise timing
• LBNL Collaboration
• Status
• NEH Laser Status

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UV pulse goals

• IR to UV conversion efficiency gt 10 , 2.5 mJ
  output _at_ 255 nm
• 252-258 nm, lt 2 energy stability
• 120 Hz, MTBF gt 5000 hours

Spatial Profile FWHM 1.2 3.0 mm
Temporal Profile FWHM 10 ps (5-20 ps)
90-10 rise and fall times lt 1 ps
flat-top, lt 8 peak-to peak
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Transport
Laser Bay
Launch System
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Accomplishments

• Great Up Time!
• 20 weeks of commissioning
• Three 8 hour downs Hot swappable parts will be
  here before next run
• One 3 hour down my fault
• 2 hours per week for locking problems
• 98 up time
• Solved spatial flutter problem further
  improvement expected
• gt500 mJ on Cathode spec was 250
• lt1.5 rms stability spec was 2

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Commissioning Issues

• Transport Tubes
• 10m long
• Hydro-carbons coating and damaging inside of
  windows when exposed to UV
• Dust inside tube settling on inside of windows
  Damage and diffraction
• Will go to less expensive windows and on site
  pump so the windows can be replaced more quickly.

Tubes cleaned last week
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Commissioning Issues

• Oscillator Problems
• Picomotor translation stage instability
• Femtolase will replace
• Coarse control currently disabled/manual
• Phase ambiguity due to locking at 476MHz
• Impacts phasing of RF
• This oscillator does not self start mode-locking
  or RF locking
• Femtolase will replace this oscillator with an
  all new unit that should address all of these
  issues

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New master oscillator from Femtolasers

• Narrower bandwidth requested to have higher
  spectral intensity and get a better seeding in
  the Regen (before FWHM 30 nm)
• Crystal is sealed in airtight cavity to avoid
  contamination (no more weekly cleaning, endurance
  test made during 200 hours)
• Remote starting capability

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New Femtolock driver for the oscillator

• Oscillator is first locked to 119 MHz and then to
  476 MHz no more 476 MHz bucket ambiguity.
• Lock button added to be lock always on the same
  bucket.
• RF- locking loop and lock button can be run
  remotely.

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Jedi Pump Laser

• Failure of Q-switch driver
• We diagnosed.
• Thales rushed a board and technician to us.
• 3 Days lost
• Various chiller problems
• Now have local source of spares
• Began purchasing spares in November
• CR Delayed order placement
• Should receive in August
• Hot swappable spares

Spare Jedis are installed and operational
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Commissioning Issues
Cross correlator
Streak Camera
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Temporal Pulse Shaping

• The achieved temporal pulse shape meets physics
  requirements for the injector commissioning
• Plan to improve the temporal shape
• Replace the Lyot filter in the regen amplifier by
  the edge mirrors this will reduce oscillations
• Continue working on the Dazzler settings and the
  optimum UV conversion crystals lengths
• Thales engineers are coming back in September to
  continue working on shaping
• Plan B to use stacking of Gaussian pulses
• Design and parts for pulse stacking are in place

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Temporal Pulse Shape - Now
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Commissioning Issues

• Newport aspheric telescope
• Converts Gaussian to flat-top
• Requires good Gaussian input
• Very sensitive to alignment
• Aperture is just as good and much simpler to
  align
• Allows flexibility
• Simplifies overall transport

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New Transport Layout
Zoom Telescope
Iris Wheel
Pulse Stacker
Beam Attenuator
Vacuum Tube to Gun
UV Beam Output
Active Steering Stabilization
Insertable Power Meter
Insertable Power Meter
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Option of Focusing the Beam on the Cathode
F4F55000 F61500
Removable Lens LDave F3m Z-adjustment of L6
changes the beam size on the cathode
L4
Transport tube
Table in the tunnel
Steering system
L5
Photocathode
Shutter
Active Steering Stabilization
L6
LDave
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No Major Changes to Vault Transport
C2
M4
UV plates for Cameras
L5
Cathode Cleaning Lens
M5
L6
M3
C1
M2
VC
Power Meter
M1
Cathode
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Spares

• We do not have a complete hot swappable laser
  system.
• Two Spare Jedis, power supplies and chillers have
  been received and installed
• Millenia pump laser and spare chiller has been
  received and installed
• We believe all long lead items that could fail
  are now covered with spares

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Future - Hand Over to Ops

• Now
• Develop procedures for laser
• Automate things that can and need to be automated
• August 07 Down
• Train Operations Group on typical Operation
  Procedures
• Hand off laser by Jan 08
• Laser Group will support Ops
• Scheduled Maintenance
• Issues that arise outside of the typical
  operation envelope

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Normal Operations

• The daily operation of the laser which, with the
  new transport system and oscillator, will be
  controlled from MCC. This will be the
  responsibility of the Accelerator Operations
  Department. Training of the operators, documented
  operating procedures as appropriate, and support
  during the transition will be the responsibility
  of the Laser Group. Operating procedures and
  documentation must conform to the document
  control policies of the Accelerator Operations
  Department. The Laser Group is responsible for
  ensuring that engineered protection systems are
  in place to ensure the safety of personnel and
  the protection of the equipment.

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Daily or Shift-wise Parameter Logging

• The Laser Group is responsible for developing
  control-system based facilities and software to
  monitor and record laser parameters as needed to
  support the efficient operation and maintenance
  of the laser systems. These facilities will
  function automatically as much as possible
  however, some logging activities may require
  operator intervention on a daily or
  shift-by-shift basis. The Accelerator Operations
  Department staff will work with the Laser Group
  to develop efficient ways to achieve this.

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Scheduled Maintenance

• Maintenance of the laser and associated
  equipment will be the responsibility of the Laser
  Group who will work with the Accelerator
  Operations Department to develop policies and
  procedures that work for both groups, within the
  established ASD framework for coordinating
  accelerator maintenance activities.

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Unscheduled Problems

• This will be the responsibility of the Laser
  Group who will designate someone on call during
  commissioning shifts. The Laser Group will also
  provide the Accelerator Operations Department
  with a pager number and/or call list to expedite
  contact with a qualified laser person when a
  problem arises whenever the laser systems are
  scheduled to be operated. The information will
  be provided in the form of one or more pages that
  can be incorporated directly into the ASD Call-In
  Lists binder.

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LCLS High Precision Timing

• SLAC/LBNL collaboration to develop system for
  high precision (lt100 fsec) delivery of timing
  reference from RFPC laser to X-ray Endstations.
• SLAC/LBNL MoU signed and project goals and
  responsibilities specified
• 30 month project with Aug 07 start with 2.1M
  budget for LBNL
• LBNL project team assembled. SLAC contacts
  identified.
• Conceptual design review planned for late
  Nov.-early Dec. 07

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Development Status

• Transmission of S-band master oscillator over
  optically stabilized fiber shows lt40 fsec
  stability over 24 hours using feedforward
  correction for group/phase velocity dispersion.
• Still tracking down systematic effects with
  possible improvement
• System now installed in chassis for tests in SLAC
  tunnel

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RF transmission design

• Design of final timing system in progress.
• Procurement of components in progress.

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Timing Plans

• Three main phases
• Phase I
• Stabilize an optical fiber in SLAC tunnel and
  klystron gallery using already built LBNL
  hardware. Goal is to understand relative
  thermo-acoustic environment. Hardware returns to
  LBNL after test.
• Transmit RF over stabilized fiber in loopback
  mode (i.e. loop fiber back to source).
• Perform attenuation vs. time measurements of
  fiber to look at radiation damage effects.
• Phase 2
• Build core of LCLS timing stabilization hardware
• provide digitally controlled GVD correction
• engineer digitally controlled transmitter and
  receiver
• develop system diagnostics
• provide basic connectivity to LCLS controls
• Install and test at LCLS
• Phase 3
• Specify (LBNL), procure and install (SLAC) fiber
  for final timing
• Deliver, install, and test final LCLS timing
  system (4 stabilized fiber lines, expandable to
  16)
• full system diagnostics and controls
• full connectivity to LCLS controls

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The NEH has a centralized laser bay which
transports beams to 3 experimental hutches
Near Experiment Hall Laser Bay Floor
Laser Hall
LCLS X-ray Beam
To Far Hall
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The 3 experimental hutches are located one floor
below the laser bay
Laser Bay
Sub-Basement of Near Experiment Hall
Transport Tubes
Hutch 1
AMO
LUSI XPP
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Near Hall Lasers

• NEH LSS design underway
• PDR held on Oct. 18
• ESD and SOP next

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Main Control of the LSS is in the Laser Hall
LSS Status Sign
Door Interlocks
Door Interlocks
Laser Bay
LSS Control Panel
Badge Reader
Transport Shutters
Crash Panel
LSS Status Sign
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Near Hall Lasers

• NEH LSS design underway
• PDR held on Oct. 18
• ESD and SOP next
• AMO Laser
• PRD coming soon
• Purchased for delivery in October 08
• LUSI XPP Laser
• Will use AMO laser for initial experiments
• Dedicated laser in 2011 or 2012
• Interface with XPP has been defined, interface
  document soon.

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Summary

• Injector laser
• Modifications for automation underway
• Procedures under development
• Hand-off begins January
• Spares are here
• Precision Timing
• Project is finally officially underway
• Prototype will be tested during next run
• NEH Lasers
• LSS design underway
• Laser procurement process beginning now
• Receive laser in October 08

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End