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Project A.3.5

Laser-driven ion acceleration

The laser pulses from CALA will be cleaned from pre-pulses by a plasma mirror. At intensities of up to 3x1022 W/cm2 in the case of ATLAS-3000 focused onto diamond-like carbon (DLC) foils mainly proton and carbon ions are accelerated in the radiation-pressure-acceleration (RPA) regime to energies on the order of 100 MeV/amu. The ions’ angular and energy distribution will be characterised with magnetic spectrometers and dose-sensitive area detector stacks and later the 3D-detector developed in C.3.1. The laser-target interaction will also be studied through secondary radiation such as electrons, UV, X- and y-rays.

The laser field will be characterised before and after the interaction via frequency-resolved optical gating. Temporally and spatially resolved interferometry of the interaction region will be used to map the evolution of the plasma, i.e. the process of ion acceleration. Finally, advanced target geometries such as micro-focusing elements and shaped targets will be used to further increase the ion energies. In the ultrafast radiation biology experiments the radiation damage mechanisms of these ions will be investigated. Likewise, the biomedical beamline and radiation therapy depend on the ion beams from LION.

Laser-driven particle acceleration

Laser driven particle acceleration happens on extremely short spatial scales of micrometres to centimetres. The main interest of our research here is the further understanding of different acceleration processes and the development of new technologies for potential applications, including medicine. For instance, we successfully demonstrated extraordinarily collimated proton beams with the aid of nanometer DLC foils and explored it for radiobiological investigations at MPQ. Future developments will be based on our developing laser systems in Garching with increased laser peak power, but also on improved targets which are being developed in-house.

Study of electron dynamics in (over)dense plasmas

Planar Nano-targets such as DLC foil offer unique properties for studying the motion of electrons in dense plasmas. They can form relativistic mirrors or dense electron sheets for generating ultraviolet radiation with sub-fs duration. Most importantly, however, it is the electrons dynamics which determines the functionality and efficiency of ion acceleration with high intensity laser pulses.

Development of advanced optical diagnostic methods for relativistic laser plasma physics

Optical diagnostic techniques are essential for a reliable and efficient operation and control of our laser plasma sources. Moreover they also represent powerful tools to shed light onto the underlying physical processes revealing crucial plasma parameters like electron densities with unprecedented accuracy and resolution in space and time. Novel ultrafast time-resolved experimental techniques imaging the plasma evolution are under development as well as focus optimization and monitoring systems. Additionally automated feedback control over relevant laser parameters via auto focusing and alignment should be achieved. Ultimately those techniques will result in improved and more stable ion acceleration, e.g. by better control of the laser contrast at the target via optimized plasma mirrors. Aiming forbiomedical applications online monitoring of the source is a key feature. In addition, those techniques are a step stone for studies in ultrafast interaction of charged particles with (biological) matter.

Fully isolated dense plasmas

The investigation of isolated, levitating targets with extensions similar to the lase focal spot is enabled by Paul-trap technology. It allows detailed studies of the interaction of laser pulses with dense plasmas in a nearly closed system and will provide a unique test ground for the generation of fast particles and radiation.

Numerical simulations

Particle-in-cell (PIC) simulations are a standard tool in laser plasma physics. We utilize a variety of 1, 2 and 3D codes, including PSC (H. Ruhl) and KLAP (X. Yan).