Sample Problem: Cylindrical Hohlraum at OMEGA

Setting Laser Beam Parameters

In this example, we set up the laser beams such that:

• 10 beams enter the hohlraum, in 2 cones, all through one LEH.
• Each beam has a 1 ns square pulse with a peak power of 0.5 TW and a 0.1 ns rise time.

The clustering of the beams is given by:

This grouping of beams into clusters was determined by examining the locations of laser ports in the coordinate system of the hohlraum. For Cones 1 and 2, the laser beams enter the LEH at angles of 21 and 42 degrees, respectively.

To do this:

• Select all of the laser beams, and select Lasers | Set pointing.
• Set the reference coordinate system to "Hohlraum_transparent_LEH_1".
• Since the beams point to the center of the LEH (i.e., the origin of the LEH coordinate system), user zero for the x, y, z positions.
• Set the focus offset to 0.06 cm.
• Select all of the laser beams, and select Lasers | Set powers.
• Check the Variable radio button, and press the Table button.
• Enter the times (sec): 0.0, 0.1e-9, 1.1e-9, and 1.2e-9 in column 1 of the table.
• Enter the powers (TW): 0.0, 0.5, 0.5, and 0.0 in column 2 of the table.
• In the table dialog, press OK.

All laser beams are now set up.

To show the beams in the main graphics window, see Displaying Laser Beams.