Implosions of spherical and cone-in-shell targets in direct-drive inertial confinement fusion (ICF) are studied with proton radiography. Time-gated, 15 MeV proton images provide a unique and comprehensive picture of ICF implosions that cover all the implosion phases from acceleration, through coasting, deceleration to stagnation. A self-generated internal radial electric field that reserves the direction during the course of implosions is observed. It is initially directed inward (at ∼109 V m-1), eventually reverses direction (∼108 V m-1) and is probably the consequence of the electron pressure gradient. Monte Carlo simulations quantitatively confirm the observations of the electric field and its evolution. The observations are compared with self-emitted x-rays and hydrodynamic simulations.
ASJC Scopus subject areas
- Nuclear Energy and Engineering
- Condensed Matter Physics