Electron extraction from an expanding laser induced plasma cathode

Summary form only given. The development of a bright and pulsed source of low energy (multi-keV) electrons is essential to measure cross sections of nuclear excitation by inelastic electron scattering which are expected to occur in hot and dense plasmas^1-4. Due to the small values of the calculated cross sections of this excitation process (10^-33/10^-30 cm²), bunches of electrons with up to 10¹³-10¹⁴ particles in a few tens of ns are necessary with energies ranging from 10 keV to 100 keV. We are developing an original electron source based on the capacity of laser heated plasmas to produce large numbers of free electrons at low energies (a few eVs). These electrons could be extracted and post-accelerated by traditional electrostatic optics. First studies have been performed to characterize the dynamics of the expanding plasma produced with a ns laser pulse at 10¹³ W.cm^-2 in which 10¹⁵ free electrons are produced⁵. Using electrostatic devices, electron bunches have been extracted from the expanding plasma in an energy range of a few keV. Several characteristics of these electrons have been measured and confronted with PIC simulations in order to better understand the dynamics of the extraction, and to identify key parameters to optimize the number of extracted electrons.