Effect of higher z dopants on implosion dynamics: X-ray spectroscopy

Low-z dopants such as argon are used to characterize the plasma properties in imploding inertial confinement fusion (ICF) capsules. Higher z dopants will be used as the temperature of the capsules is increased especially as we approach ignition on the National Ignition Facility (NIF). The presence of the higher z dopants also affects the dynamics of the implosion as it increases the electron density, which increases the radiation losses from the plasma allowing the plasma to compress to a smaller volume. In the present study, we examine the effects at higher dopant densities. While a normal glass capsule loses energy to radiation during compression, the high-z shells will confine the radiation even as equilibrium burn is approached. We have fielded thin 1-mm diameter glass shells filled with varying amounts of xenon and krypton gas to study the progression from non-equilibrium to equilibrium burn as the dopant gas concentration is increased. The shells used for these experiments also contained 3He to measure the proton spectrum from the D3He reaction providing information about the target temperature and the density-radius product, ρR. Here we present results using the X-ray measurements, as well as discuss some of the issues and the progress we made.