[en] The main characteristics of the electron beam in an induction accelerator are a very high current beam (>10 kA) and a long pulse duration (∼100 ns). In this paper, we first will describe space charge effects which affect emittance at low energy and then we will discuss the principal instabilities which lead to an emittance growth as the beam propagates further along the accelerator. Some simulation results are presented and beam diagnostics used to characterize these phenomena are described. (author)

[en] Laser damage growth on the exit surface of fused silica optics is considered as exponential, the growth coefficient depending essentially on fluence. In this presentation, experiments with large beams have been carried out at 351 nm under nanosecond pulses. A statistical analysis has then been conducted leading to a refined representation of the growth. The effect of several parameters has also been taken into account to describe precisely the growth phenomenon. Finally, the two main parameters reporting the growth are the mean fluence and the size of the damage sites. Contributions of other parameters have been estimated too: the number of neighbors around the damage site, the shot number...From experimental results, a model based on a statistical approach has been developed that permits the description of a complete sequence of growth. At the end, the knowledge of damage initiation and damage growth permit the determination of the lifetime of optical components illuminated with successive shots. (authors)

[en] LELIA is an induction accelerator designed and built at CESTA for FEL applications. The objective of this program is to produce a high-brightness and high-average-power electron beam. An injector (1.5 MeV, 1.5 kA, 50 ns flat top pulse) is now under test. It uses an Osmium dispenser cathode and ten induction cells driven by a high voltage pulse generator (150 kV, 60 ns, 2 Ω). It is able to work at high repetition rate (1 KHz). Initial operation began in June last year. Beam characteristics have ben measured and compared with numerical simulations

[en] Up to now, laser damage growth on the exit surface of fused silica optics has been mainly considered as exponential, the growth coefficient depending essentially on fluence. From experiments with large beams carried out at 351 nm under nanosecond pulses, a statistical analysis is conducted leading to a refined representation of the growth. The effect of several parameters has been taken into account to describe precisely the growth phenomenon. The two principal parameters proved to be the mean fluence and the size of the damage sites. Nevertheless, contributions of other parameters have been estimated too: the number of neighbors around the damage site, the shot number, etc. From experimental results, a model smoothed on a statistical approach is developed that permits the description of a complete sequence of growth. To evaluate the relevance of the modeling approach, the occluded area estimated from modeling is compared with the ones experimentally measured. For this purpose, numerical growth methods have been developed too. It is shown that the approach outlined is appropriate for a more precise description of the growth. (authors)

[en] The LELIA accelerator is a test bed for induction technology; it will also serve as a driver for microwave FEL experiments. In a first step an 1.5 MeV induction injector driven by a high voltage pulse generator was constructed and tested. The beam transport along the injector was also measured, and its energy spectra and whole emittance were determined. The final objective is to produce a high current (1-3 kA) and high brightness electron beam with an energy of 3 MeV. (R.P.) 2 refs.; 4 figs

[en] The Laser Integration Line (LIL) was first designed as a prototype to validate the concepts and the laser architecture of the Laser MegaJoule (LMJ). The LIL facility is a 4-beam laser representing a quad structure of the LMJ. A set of test campaigns were conducted to safely ramp up laser performance. The main goal was to measure quad-specific features such as beam synchronization and focal spot (size, smoothing contrast ratio or irradiation nonuniformity) versus the LMJ requirements. Following the laser commissioning, the LIL has become a major instrument dedicated to the achievement of plasma physics experiments for the French Simulation Program and was also opened to the academic scientific community. One of the attributes of the LIL facility is to be very flexible to accommodate the requests of plasma physicists during campaigns. The LIL is constantly evolving to best meet the needs of target physicists. Changes made or planned are either to improve the quality of laser beams, or to increase the LIL Energy-Power operating space. To optimize preparation and design of shot campaigns, the LIL performance status has been elaborated. It gives information about the characteristics of the laser in terms of near field and far field, defines the steps to maintain performance, explains how the facility responds to the request, details settings (smoothing, shaping of the focal spot, energy, temporal pulse shaping, beam pointing) and gives the limits in energy and power. In this paper, an overview of the LIL performance is presented. (authors)