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Manipulation and Characterization of Ultrashort Laser Pulses for High-quality Electron Bunch Acceleration - position filled

(Consiglio Nazionale delle Ricerche - Istituto Nazionale di Ottica)

The production of high-quality electron bunches, in terms of their energy spectrum and emittance, is currently recognized as one of the main challenges for the development of innovative, plasma-based electron accelerators for a wide range of applications. It is crucial both for driving secondary sources and for the efficient development of multi-stage acceleration schemes delivering multi-GeV bunches. It heavily depends on the capability to inject bunches into the plasma wave in a well-localized and controlled manner.

While the quality of bunches produced via self-injection in the so-called bubble regime has been steadily increasing in recent years, advanced injection schemes have been studied, such as injection in density down-ramp and shock, colliding pulses, and ionization injection. In the framework of the latter approach, a “two-colour” scheme, envisioning the usage of a long (~10-micron) wavelength pulse to drive the plasma wave and a shorter wavelength pulse for ionization injection, was already proposed in 2014. More recently, an evolution of this scheme, called “REMPI”, was proposed by the CNR-INO group and predicted to deliver bunches with very high quality while using a single Ti:Sapphire laser.

The approach is based on the use of a train of ultrashort pulses to resonantly drive the plasma wave while avoiding any electron injection and of a pulse at a harmonic of the laser fundamental frequency to trigger the ionization injection. The scheme is being considered as one of the possible approaches for the EuPRAXIA laser-driven injector. One of the main challenges is the generation of a train of ultrashort pulses from a single laser.

This research project aims at addressing the underpinning issues and providing one (or more) optical schemes for pulse train generation suitable for laser wakefield acceleration. The Fellow will study the ultrashort and ultra-intense fields, as well as the longitudinal (time-related) functions of the focused beam. The possibility of wavefront-tailoring to match the focusing/propagation properties of the different pulses will also be studied. Finally, the stability and reproducibility of the obtained laser pulse trains will be investigated in detail. The research will include theoretical and numerical studies in ultrashort pulse optics, as well as experimental activities at the Intense Laser Irradiation Laboratory of CNR-INO.

The Fellow will have access to the wide-ranging EuPRAXIA-DN training program, which will include several international schools and workshops on plasma accelerator science and technology, as well as complementary skills. Secondments to network partners ELI beamlines (laser R&D), ELI-NP (REMPI), and the UK-based company D-BEAM (advanced instrumentation) will complement the interdisciplinary training.

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