Sample Problem: Cylindrical Halfraum at OMEGA

Setting Up the Grid: Backlighter and Support Wire

Here, we describe how to set the position of a backlighter and its support wire.

We position the backlighter on the laser entrance hole (LEH) side at a distance of 0.15 cm (1500 microns) from the LEH. Since the Halfraum has a length of 0.12 cm, the position is at z = 0.21 cm (= 0.15 + 0.5*0.12).

To add the backlighter:

• Select Target | Add Object.
• Select "Rectangle" for the target component type.
• Set the object name to "Backlighter".
• In the Position tab of the Object Parameters Dialog:
• For the Reference Coordinate System, select "Halfraum" (note that the Halfraum has been set up prior to setting up the Backlighter).
• Set the object position at r = (0, 0, 0.21).
• Use the default orientation angles (all angles zero). The backlighter is perpendicular to the halfraum axis.
• In the Size/Gridding tab of the Object Parameters Dialog:
  • Set the x-length to 0.155 cm (this is approximately the diameter of the halfraum).
  • Set the y-length to 0.08 cm.
  • Set surface normals down (facing the halfraum).
  • Use 11 grid points along both the x and y dimensions.
• Select "OK". (The backlighter is added to the graph frame.)

To adding the support wire for the backlighter:

Here, we set the wire at the radius of the Halfraum, and parallel to its axis.

• Select Target | Add Object.
• Select "Cylinder" for the target component type.
• Set the object name to "BL_wire".
• In the Position tab of the Object Parameters Dialog:
  • For the Reference Coordinate System, select "Halfraum".
  • To specify the position of the wire, let's use a cylindrical coordinate system; so select "Cylindrical".
  • Set the object position at r = 0.08 cm (at the Halfraum radius), and z = 0.135 cm (this positions the mid-point of the backlighter wire such that it extends from the Backlighter to the Halfraum).
  • Use the default orientation angles (all angles zero). This leaves the support wire parallel with the Halfraum axis.
• In the Size/Gridding tab of the Object Parameters Dialog:
  • Set the radius to 0.001 cm (the support wire is thin).
  • Set the length to 0.15 cm.
  • Set surface normals out.
  • Use 2 grid points along the wire's z-axis, and 4 azimuthal grid points (low-resolution gridding is sufficient for the backlighter support wire).
• Select "OK".