In-flight measurements of capsule shell adiabats in laser-driven implosions.

ABSTRACT

We present the first x-ray Thomson scattering measurements of temperature and density from spherically imploding matter. The shape of the Compton downscattered spectrum provides a first-principles measurement of the electron velocity distribution function, dependent on T(e) and the Fermi temperature T(F)∼n(e)(2/3). In-flight compressions of Be and CH targets reach 6-13 times solid density, with T(e)/T(F)∼0.4-0.7 and Γ(ii)∼5, resulting in minimum adiabats of ∼1.6-2. These measurements are consistent with low-entropy implosions and predictions by radiation-hydrodynamic modeling.