Sample Problem: Z-Pinch Hohlraum

Setting Up the Grid: Detector with Aperture

Detector:

We simulate the detector by putting a 1 cm x 1 cm square (a single polygon) along a line-of-sight typical of that used in a Z experiment. The detector polygon is put 200 cm away from the pinch (smaller than in experiments, but still large compared to the size of the pinch), as its normal vector faces the pinch. The detector is 12 degrees above the horizontal (78 degrees from vertical).

• Select Target | Add Object.
• Select "Rectangle" for the target component type.
• Set the object name to "Detector".
• In the Position tab of the Object Parameters Dialog:
• For the Reference Coordinate System, use "Target Chamber".
• Use a spherical coordinate system to set the detector position.
• Set the object at: radius = 200 cm, theta = 78 degrees, phi = 0 degrees.
• Use the orientation angles: polar = 78 degrees. azimuthal = 0 degrees.
• In the Size/Gridding tab of the Object Parameters Dialog:
  • Set both the x-length and y-length to 1.0 cm.
  • Set surface normals down.
  • Use 2 grid points in the both the x- and y-directions (this provides 4 nodes, one polygon).
• Select "OK".

To set the viewing position so that the pinch can be viewed from just behind the detector, select Set | Viewing Position. The enter 201 cm for the distance from the origin, the set the polar angle to 78 degrees and azimuthal angle to 0 degrees.

Aperture for Detector:

We assume an aperture located a distance of 10 cm from the pinch, with a slot height of 1.0 cm and a slot width of 0.7 cm.

• Select Target | Add Object.
• Select "Rectangle" for the target component type.
• Set the object name to "Aperture".
• In the Position tab of the Object Parameters Dialog:
• For the Reference Coordinate System, use "Target Chamber".
• Use a spherical coordinate system to set the aperture position.
• Set the object at: radius = 10 cm, theta = 78 degrees, phi = 0 degrees.
• For orientation angles, set to polar = 78 degrees.
• In the Size/Gridding tab of the Object Parameters Dialog:
  • Set the x-length to 5 cm and the y-length to 8 cm.
  • Set surface normals up.
  • Use 2 grid points in the both the x- and y-directions
• Select "OK".

We next need to apply a clipping volume equal to the size of the aperture.

• In the Target Components List, select Aperture.
• Then select Target | Clip Object With (or select the Clip Target Component tool button).
• For the clipping volume type, select "Box".
• Rename the clipping volume, if desired.
• In the Position tab of the Clipping Volume Parameters Dialog:
  • Use the default object position: r = (0,0,0).
  • Use the default orientation angles (all zero).
  • For the reference coordinate system, clipping volumes use the coordinate system of the object they are clipping.
• In the Size tab of the Clipping Volume Parameters Dialog:
  • Set X to 1.0 (this sets the height of the aperture to 1.0 cm in this example).
  • Set Y to 0.7(this sets the width of the slot to 0.7 cm).
  • Set Z to 0.1 (this depth is arbitrary).
  • Remove the interior (of the clipping volume).
• Select "OK".