Importing SRF File Data into VISRAD

VISRAD can import laser beam data from a file generated by the SRF Database (SRD-DB) at the University of Rochester's OMEGA laser facility.

To import SRF file data into VISRAD, select File | Import Laser Beam Data. VISRAD laser beam parameters will be overwritten by the data contained in the SRF data file.

At present, mapping of SRF Pointing, Energetics, and Spatial Profile data to VISRAD laser beams is performed as follows:

• General:
  • VISRAD Cluster names are set to SRF Beam Group names.
  • Beams are grouped into VISRAD Clusters based on the SRF Beam Group name associated with each beam.
  • Beams with the group name "Ride Along" are ignored.
    
    
• Pointing Data:
  • VISRAD supports specification of Pointing parameters using TCC, target chamber coordinates (r,θ,φ), or a distance toward a port. SRF Pointing values are mapped directly to VISRAD.
  • Focusing and Focusing Units:
    • If units are mm (lens position), VISRAD Focus Point Offset is set to value of SRF Focusing.
    • If units are um (spot size), VISRAD Focus Point Offset is set to:
      • Focus Offset = f# * sqrt( focus ² - 4d_o ²), where d_o = spot radius for DPP (for no DPP, d_o = 0)
      • Focus Offset = 0, if | focus | ≤ 2d_o for DPP, and ≤ 100 microns in cases with no DPP.
    • If units are R multiples, VISRAD Focus Point Offset is set to:
      • Focus Offset = focus * R(sphere), if there is one and only one sphere in the target grid.
      • Focus Offset = 0, otherwise.
• Energetics Data:
  • Energy and Energy Units:
    • If units are J/Beam, beam powers in VISRAD are set to the SRF Energy in each beam, and assume a 1 ns pulse width. (e.g., 500 J/beam => 0.5 TW)
    • If units are not J/Beam, beam powers are set to 1 TW.
      
      
• Spatial Profile Data:
  • SRF DPR value: DPR modeling is turned off for any beams that use DPPs.
• SRF DPP (Distributed Phase Plate) Name:
  • To view OMEGA DPPs currently supported by VISRAD, see list of DPP parameters for OMEGA.
  • For all other SRF DPP Names, VISRAD sets the Spatial Profile Model to Uniform (no DPP).
• SRF elliptical phase plate Orientation value: Mapping of beam rotation angles is currently supported for the following elliptical DPPs:
  • E-IDI-300 (Pent and Hex ports)
  • E-SG4-865 (Hex ports)
  • E-SG10-300 (Hex ports).

 

OMEGA Beamline 25 HR Pickoff:

When the 2w/4w beam propagates along BL-25 and is intercepted by an HR pickoff and re-directed to port P9, the beam is represented by a Custom Laser Beam in VISRAD. When importing data from the LLE SRF database, whether directly from the database or from an XML-formatted file generated by the SRF-DB, a custom beam is automatically generated with name "Beam_25_P9", and is placed in a cluster named either "2w Beam" or "4w Beam".

If VISRAD detects that the mapping of some SRF beam parameters is not yet supported (such as a DPP Name or Focusing Units), a warning message is displayed.

The following SRF parameters are not utilized when importing SRF data into VISRAD.

• SRF Beam Group Termination
• Beam Delay
• SRF Report Group

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