One of the features of ultra high intensity (UHI) short
pulse laser–matter interactions is the prospect of
creating a cheap, compact source of hard X rays
with femtosecond pulse duration. The properties of such
Kα sources are studied using analytical and
numerical models of hot electron generation and subsequent
transport in a range of materials (Reich et al., 2000).
First, we find that there is an optimum laser intensity for
Kα generation from bulk targets, which scales as
Z4.4. Second, we show that efficient hard
X-ray pulses with durations below 100 fs can be generated at
intensities of ∼1016 W/cm2.