An end-pumped high-power Nd:YAG zigzag slab continuous wave laser amplifier was designed through a computational simulation to minimize the wavefront distortion of the output laser beam. The pump beam delivering optical system was optimized with an acylindrical slow-axis lens to lower the distortion of nonzigzag propagation for the beam height axis. In addition, the wavefront distortion of the zigzag propagation for the beam width axis was studied and minimized by slightly changing the doped YAG length. The simulation results of the final design showed a peak-to-valley optical phase difference (OPDP−V) of 0.83 μm and a very low beam quality of 1.19× diffraction limit, even with a total pump power of 10 kW.
It has been found that more intense proton beams are generated from plastic foils than metal foils irradiated by an ultraintense
laser pulse. The acceleration model, ARIE (Acceleration by a Resistively Induced Electric field) accounts for the
experimental observations from plastic foils compared with metal foils. Proton beams on foil thickness and laser prepulse
have been observed, which is also well described by the ARIE model. An experiment with an aluminum-coated
plastic target strongly suggests that front side acceleration is a dominant acceleration process in plastic targets. We also
suggest that a vacuum-sandwiched double layer target could effectively enhance the laser contrast ratio, which was
investigated in the combination of a two-dimensional hydro code and a two-dimensional PIC (Particle-In-Cell) code.
A compact gamma-ray source using laser-accelerated electron beam is being under development at KAERI for nuclear
applications, such as, radiography, nuclear activation, photonuclear reaction, and so on. One of two different schemes,
Bremsstrahlung radiation and Compton backscattering, may be selected depending on the required specification of
photons and/or the energy of electron beams. Compton backscattered gamma-ray source is tunable and quasimonochromatic
and requires electron beams with its energy of higher than 100 MeV to produced MeV photons.
Bremsstrahlung radiation can generate high energy photons with 20 - 30 MeV electron beams, but its spectrum is
continuous. As we know, laser accelerators are good for compact size due to localized shielding at the expense of low
average flux, while linear RF accelerators are good for high average flux. We present the design issues for a compact
gamma-ray source at KAERI, via either Bremsstrahlung radiation or Compton backscattering, using laser accelerated
electron beams for the potential nuclear applications.