Monoenergetie-Proton-Radiography Measurements of Implosion Dynamics in Direct-Drive Inertial-Confinement Fusion

摘要

Time-gated, monoenergetic radiography with 15-MeV protons provides unique measurements of implosion dynamics in direct-drive inertial-confinement fusion. Images obtained during acceleration, coasting, deceleration, and stagnation display a comprehensive picture of spherical implosions. Critical information inferred from such images, hitherto unavailable, characterizes the spatial structure and temporal evolution of self-generated fields and plasma areal density. Results include the first observation of a radial electric field inside the imploding capsule. It is initially directed inward (at ～10~9 V/m), eventually reverses direction (～10~8 V/m), and is the probable consequence of the evolution of the electron pressure gradient.