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This thesis focuses on the optimization and control of laser-driven plasma-based acceleration, whichinvolves the driver laser pulse, the accelerated electrons and the subsequent generation of x-rays.

In laser wakefield acceleration (LWFA), a high-power laser pulse, typically with terawatt-levelpower, is focused tightly into a gas, reaching intensities on the order of > 1018 W/cm2. Even at the leading edge of the pulse, the gas becomes fully ionized, so the main part of the pulse interacts primarily with plasma. The relativistic ponderomotive force expels plasma electrons from the high-intensity region, creating a void, or wake, just behind the laser pulse. Within this ion cavity, the charge separation generates strong electric fields on the order of TV/m, enabling electrons injected into the cavity to be accelerated to hundreds of MeV over just a few millimeters. Various injection schemes allow for control over the energy and energy spread of the electron bunch. However, producing monoenergetic electron bunches remains a significant challenge, and some energy spread is always present. The maximum achievable energy is limited by dephasing, the distance over which electrons gain energy before being decelerated.

The ion cavity is nearly spherical, resulting in strong radial fields. Consequently, electrons are not only accelerated along the laser’s propagation direction, but also oscillate transversely about the optical axis. These oscillations lead to the emission of x-ray radiation. However, because of this motion, electrons exiting the cavity exhibit a large divergence, and the resulting x-rays inherit this
broad angular spread.

This thesis addresses each of these limitations. By tailoring the plasma density profile at the start of the acceleration process, the energy spread of the electron bunch can be reduced. The usage of a high-density plasma lens significantly decreases electron beam divergence across a broad energy range. Within this lens, electron deflection results in x-ray emission with a divergence approaching
the incoherent limit. Furthermore, by introducing a high-density region at the end of the acceleration stage, it becomes possible to extend the maximum energy gain beyond the conventional dephasing limit of LWFA.