The acceleration of electrons injected in a plasma wave generated by the laser wake eld mechanism has been observed. A maximum energy gain of 1.6 MeV has been measured and the maximum longitudinal electric eld is estimated to 1.5 GV/m. The experimental data agree with theoretical predictions when 3D e ects are taken into account. The duration of the plasma wave inferred from the number of accelerated electrons is of the order of 1 ps. 41.75. Lx,52.40.Nk Typeset using REVT E X 1
This report presents the conceptual design of a new European research infrastructure EuPRAXIA. The concept has been established over the last four years in a unique collaboration of 41 laboratories within a Horizon 2020 design study funded by the European Union. EuPRAXIA is the first European project that develops a dedicated particle accelerator research infrastructure based on novel plasma acceleration concepts and laser technology. It focuses on the development of electron accelerators and underlying technologies, their user communities, and the exploitation of existing accelerator infrastructures in Europe. EuPRAXIA has involved, amongst others, the international laser community and industry to build links and bridges with accelerator science — through realising synergies, identifying disruptive ideas, innovating, and fostering knowledge exchange. The Eu-PRAXIA project aims at the construction of an innovative electron accelerator using laser- and electron-beam-driven plasma wakefield acceleration that offers a significant reduction in size and possible savings in cost over current state-of-the-art radiofrequency-based accelerators. The foreseen electron energy range of one to five gigaelectronvolts (GeV) and its performance goals will enable versatile applications in various domains, e.g. as a compact free-electron laser (FEL), compact sources for medical imaging and positron generation, table-top test beams for particle detectors, as well as deeply penetrating X-ray and gamma-ray sources for material testing. EuPRAXIA is designed to be the required stepping stone to possible future plasma-based facilities, such as linear colliders at the high-energy physics (HEP) energy frontier. Consistent with a high-confidence approach, the project includes measures to retire risk by establishing scaled technology demonstrators. This report includes preliminary models for project implementation, cost and schedule that would allow operation of the full Eu-PRAXIA facility within 8—10 years.
Recent experiments [F. Dorchies et al., Phys. Rev. Lett. 82, 4655 (1999)] have demonstrated monomode guiding over 100 Rayleigh lengths (10 cm) of high intensity, ultrashort laser pulses in a dielectric capillary tube filled with low pressure He gas. A model for the propagation of femtosecond laser pulses in a capillary tube, coupled with the tunnel ionization of the gas filling the capillary tube, is derived and solved numerically using the parameters of these experiments. The simulations accurately reproduce experimentally measured damping lengths, transmitted pulse energy and spectrum at the output of the capillary tube. They show that a few cm long, homogeneous, plasma column with an electron density of the order of 1017 cm−3 is created for an incident intensity of 4×1015 W/cm2.
The structure of the wakefield is studied in a plasma column, created by a monomode laser pulse propagating in a capillary tube, filled with gas affected by tunneling ionization. Linear analytical considerations as well as self-consistent numerical simulations show that in the central bulk part of a plasma column where the laser intensity exceeds the ionization threshold, the wakefield structure is similar to that of an infinite homogeneous plasma. Near the wall of the capillary tube, where the laser intensity decreases below the ionization threshold and where the plasma density falls to zero, the curvature of the plasma wave phase front increases with the distance from the laser pulse, resulting in small-scale radial electric field which may undergo phase mixing.
We describe the first demonstration of a collisionally excited optical-field-ionization laser driven within a waveguide. Lasing on the 4d(9)5d-4d(9)5p transition at 41.8 nm in Xe8+ was observed to be closely correlated to conditions under which the pump laser pulses were guided well by a gas-filled capillary discharge waveguide. Simulations of the propagation of the pump laser radiation show that gain was achieved over essentially the whole 30 mm length of the waveguide.
International audienceIonization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99%H2 þ 1%N2. Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. The interest of this regime for optimizing the bunch charge in a selected energy window is discussed
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