The ablator “packages” are thin, planar sandwiches of actual
ablator material surrounding a very thin layer of a
spectroscopic tracer
halfraum radiation
Ge-doped or undoped plastic
NaCl
tracer
<
0.5 m
~20 m
~5 m
This
package, mounted over a hole on the outside of the hohlraum,
actually sees a time-dependent radiation field (the
“drive”) that is very similar to what’s seen by a spheric
capsule in the center of a hohlraum.
When
we see the spectroscopic signature of the chlorine
in the tracer, we know the radiation wave has reached
it.