Dynamics of charge clouds ejected from laser-induced warm dense gold nanofilms.
We report a systematic study of the ejected charge dynamics surrounding laser-produced 30-nm warm dense gold films using single-shot femtosecond electron shadow imaging and deflectometry. The results reveal a two-step dynamical process of the ejected electrons under high pump fluence conditions: an initial emission and accumulation of a large amount of electrons near the pumped surface region, followed by the formation of hemispherical clouds of electrons on both sides of the film, which escape into the vacuum at a nearly isotropic and constant velocity with an unusually high kinetic energy of more than 300 eV. We also developed a model of the escaping charge distribution that not only reproduces the main features of the observed charge expansion dynamics but also allows us to extract the number of ejected electrons remaining in the cloud.
Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Jun
J
Zhou
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Alfredo A
AA
Correa
Brookhaven National Laboratory, Upton, New York 11973, USA.
Junjie
J
Li
Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Shao
S
Tang
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Yuan
Y
Ping
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Tadashi
T
Ogitsu
Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Dong
D
Li
Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Qiong
Q
Zhou
Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Jianming
J
Cao