Measurements of the equation of state of lead under varying conditions by multiple methods.

For the past few years AWE has been pursuing a programme of principal Hugoniot EOS measurements on metals and plastics at multi-Mbar pressures. Recently we have decided to concentrate on measurements on lead by a number of different techniques to cover as much of the EOS parameter space as possible. Using the HELEN laser we have made more Hugoniot measurements from similar to800kbar to similar to10Mbar. We have also performed isentropic compression experiments up to -1Mbar using the Sandia National Laboratory's Z machine. These were on single-crystal and bulk lead and a lead-antimony alloy. These complementary experiments allow us to compare single-crystal, bulk and alloyed materials, to compare Hugoniots and isentropes at I Mbar and to compare laser-driven experiments with existing gas-gun and explosively driven data at low pressures. This presentation will describe these experiments and the results, with emphasis on the ways in which they are complementary: how one measurement can verify another, how techniques and diagnostics carry-over, and the ways in which one method can provide data not possible from another.