NIF ARC Beams

Four ARC beamlets can be added to the NIF laser system in VISRAD. To add the ARC beams, use the Lasers | Add NIF ARC Beams menu item. The four ARC beams B353A/B and B354A/B are added as Custom beams to the Laser Beams List.

The table below summarizes the ARC beamlet parameters. The angles and R refer to the angles and distance to each beamlet's turning mirror relative to TCC.

In VISRAD, each ARC beam is modeled as a beam that originates with rectangular shape at the turning mirror (e.g., 12.8 cm horizontal x 29.9 cm vertical for B353A). The beam then transitions to a supergaussian profile (if used) at the focus point using the beam profile modeling described in Setting Laser Beam Spatial Profiles.

Note that if ARC beams are turned on, beams in Quad Q35T cannot be used.

In the NIF chamber, the positioning of the steering mirror for each ARC beam is adjusted slightly to point the beam and set the defocus. However, because the change in position is small, the polar and azimuthal angles in VISRAD are not readjusted when the pointing position and focus offset are changed.

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