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Facility Notes

Omega is a 60 beam facility designed for spherical direct drive. The latest version of the system manual can be found online here, although it is worth always explicitly checking if any important information is up-to-date.

Below are some notes on the system.



  • Beam layout image

  • Chamber pressure ~1e-5 to 1e-6 Torr

  • One degree of rotational freedom on targets

  • Only backlit alignment

  • Coordinates:

    • Theta: declination from straight up (0 deg = up) range 0 to 180 (no negative)

    • Phi: (0-360deg) 

    • zero ~ North

    • Increases anti-clockwise

  • Need to be V careful with maintain up-to-date target 'drawings' ESPECIALLY any changes during manufacture


  • 45 minutes between shots (minimum)

  • Morning 4.5 hrs, afternoon 6.5 hrs

  • Typically the shot-cyle is slower before lunch:

    • Test things before lunch giving time to evaluate before shooting really begins in afternoon

  • Alternate subsequent shots between those relying on different diagnostics


  • 1st shot of day is least perfect

  • Debris shield replaced every 3 weeks (prior to cryo-shots)

  • Pointing from TCC:

    • +/-5mm in vertical

    • -9mm +15mm in horizontal

  • f/# 6.7


  • Pulse shapes must be requested at least 1 month in advance. See here

  • All beams timed as if they are to TCC - must account for this!

  • Can offset individual beams by up to ~+/-5ns on a per shot basis, but see here for exact details for each beam:

  • Pulse shapes 100ps → 4ns

  • Up to 2 pulse shapes per shot, but the way this is mapped from legs to beams is highly restrictive (see beam numbering below) 

  • Pheonix regen means can have no SSD late in time so more energy

  • Backlighter can be done separately at A split (1 → 3 beams) and can have big offset in time


  • 23, 48, 62 degree and equatorial cones in both north and south poles

  • Like a football: pentagons and hexagons

  • Beam numbering system:

    • Leg 1: clusters 1 and 4

    • Leg 2: clusters 2 and 5

    • Leg 3: clusters 3 and 6

    • numbering works by cluster|number, e.g. 62 is cluster 6, beam 2

  • Each beam is directly opposed by another

    • Must be careful target is not completely ablated


  • With SSD: 

    • 27kJ | 450J/beam (1ns square pulse)

    • ~27TW total power

    • 0.45TW/beam

  • No SSD: 

    • 500J/beam

    • 0.5TW/beam

  • The details of the pulse shape always dictates energy and peak power, so cannot assume anything until this is set​



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Brief timeline for an Omega experiment:

  • »3 months out

    • Finalize target design and submit request. Typically in April/May

  • ~4 months out

    • Submit experimental proposal with all unique configurations described (SRF and VisRad model required for each) and all diagnostics intended to be used

  • >2 months

    • Proposal approved by Facility Advisory and Scheduling Committee (FASC)

  • COB Monday 2 weeks prior to experimental shot date

    • Unique SRFs complete for review at 2-week PI brief (typically conducted on Wednesday afternoon 2 weeks prior to experimental shot date)

  • COB Monday 1 week prior to experimental shot date

    • SRF for all planned shots completed for review at 1-week PI brief (typically conducted on Wednesday afternoon 1 week prior to experimental shot date)

  • Monday of shot week

    • Brief presentation at LLE's experimental meeting

  • Day of shots

    • Arrive 7.30am (with doughtnuts, bagels and coffee)

    • 8am Brief presentation to watch crew at pre-watch brief

Click above link to see diagnostics information.

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