To
study the problem in a more controlled
way, we made the following simplifying
assumptions:
•The
laser beam power is constant over a 1ns square pulse, and uniform for each
beam (475 J/beam
for each of 15 beams).
• There is no “lip” on the halfraum
• The 15 laser beams were pointed to make a single ring of laser hot spots around the halfraum (note that this makes the
spot sizes different
for beams in different cones).
•The
witness plate and the halfraum are both made of gold (maximum albedo =
0.7)
Later we show a comparison between these “no-lip” calculations and some with lips on
the halfraum around the LEH.
Left: A typical
halfraum with a (1/4) lip over the LEH. Right: A
simplified halfraum with no lip. Some surfaces in the VisRad simulations are shown as ‘mesh’ so the viewer can see what’s
behind them.
View from center of
witness plate, looking out the LEH. On the left, a more
typical configuration with cone 2 and cone 3 beams pointed differently and an LEH lip included. On the right, the result of implementing the simplifying
assumptions.