[TEMF] Laser ion acceleration using the Draco Petawatt facility at HZDR – plasma experiments in the nearcritical density regime and radio-biological applicationONLINE ONLY

Demanding applications like radiation therapy of cancer are pushing the frontier of laser driven proton accelerators with controlled and well-defined proton beam properties. This talk will give an overview of recent achievements at the high-contrast high power laser source DRACO at HZDR providing high contrast pulses of >500 TW on target for the reliable generation of proton beams with energies of around 60 MeV. For efficient capturing and shaping of the divergent TNSA proton pulses, a setup of two pulsed highfield solenoid magnets has been developed and proven to reliably generate homogeneous depth dose distributions precisely adapted to the three-dimensional sample geometry for ultra-high pulse dose rate irradiation scenarios. Using this method, worldwide first dose controlled volumetric irradiation of in vivo samples with laser-accelerated protons were conducted.
The performance of laser based ion acceleration and the scaling of the laser energy to achieve increased ion energies strongly depend on the laser temporal contrast and its effect on the target plasma scale length. Plasma mirror setups have proven to be a valuable tool to significantly improve the temporal contrast by reducing pre-pulse intensity and steepening the rising edge of the main laser pulse. With such contrast enhancement techniques including novel diagnostic schemes, laser proton acceleration using ultra-thin foil targets as well as renewable debris-free hydrogen jets were investigated in a series of experiments within the near-critical density regime. An important implication of this is the demonstration of a credible path toward high repetition rate laser-based ion acceleration applications.