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The effect of fluctuations of the electron temperature on the population kinetics of a reduced atomic system is investigated in the case of a low density plasma, where the coronal approximation can be used. An exponential correlation function is assumed for the electron temperature fluctuations. A resonance of the average population as a function of the correlation time is observed and analyzed.

International audience; We present a simple upgrade of a time-resolved attosecond extreme ultraviolet and infrared (XUV-IR) setup designed to perform time-resolved or spectrally resolved studies of a target under similar experimental conditions. A flat XUV grating inserted in the path of an attosecond pulse train obtained via high order harmonic generation in gases is used either in the zeroth order of diffraction to follow attosecond dynamics or in the first order of diffraction to study the target spectral response with a temporally stretched single harmonic. Electron momentum measurement is performed with a velocity map imaging spectrometer, and the 10 W femtosecond laser system operating at 5 kHz provides an XUV photon flux compatible with rapid acquisition in both the monochromatic and broadband configurations. The change of experimental configuration between broadband and monochro-matic sources is rapid and performed in situ. We present the experimental implementation applied to krypton atoms and detail the capabilities and limits of this approach when an XUV grating with constant groove density is used with a converging XUV beam.

We prove Strichartz estimates on general flat $d$-torus for arbitrary $d$. Using these estimates, we prove local wellposedness for the cubic nonlinear Schrodinger equations in appropriate Sobolev spaces. In dimensions $2$ and $3$, we prove polynomial bounds on the possible growth of Sobolev norms of smooth solutions.

The discovery of an overlooked but apparently ubiquitous spike in the mid-infrared photoelectron spectra of molecular and atomic gases suggests that we don’t know as much as we thought we did about the ionization of matter in strong fields.

We report new (e,2e) and (e,3e) experiments for ionization of argon under unexplored kinematics characterized by large energy transfer to the target and where the two 'atomic' electrons carry the same kinetic energy. This opens the possibility of competition and interference between direct 3p-outer shell double ionization (DI) and indirect DI via an Auger emission from the 2p shell. The (e,2e) results are found to be in reasonably good agreement with state-of-the-art theoretical models for 2p-single ionization. The importance of the other competing processes, namely direct 3p-DI and/or Auger relaxation, not included in the models is highlighted. The measured (e,3e) angular correlation pattern displays a rich structure, partly resulting from final state interactions where the outgoing electrons tend to minimize their Coulomb repulsion. The rapprochement with the (e,2e) results allows the assignment of some of the observed peaks to given ionization mechanisms, either the two-step 2 direct 3p-DI, or a 2p-single ionization followed by an Auger emission.

A complete analysis of our recent (e, 3e) experiments on helium at 601 eV incident energy (Lahmam-Bennani et al 2003 Phys. Rev. A 67 010701) is conducted by using an approximate 6C model which accounts for the interaction between all four particles (the scattered electron, the two ejected electrons and the nucleus) in the final state. An accurate wavefunction for the initial state is also used. The agreement between experiments and theory is not always good even though most peaks and dips can be explained. Comparison is also made with the results of the first Born-BBK approximation as well as with approximate second Born results.

A novel approach to the modeling of atomic populations in turbulent plasmas is applied to ionization–recombination balance calculations. Fluctuations of the fluid parameters are retained using a time-dependent statistical approach, suitable for cases where the turbulence characteristic times are of the same order as or smaller than the typical atomic relaxation times. We show that the populations are sensitive to the shape of the autocorrelation function of the fluctuations. An illustration is proposed through an ideal two-level system forced by non-Markovian temperature fluctuations.

In lithium-wall-conditioned tokamaks, the line radiation due to the intrinsic impurities (Li/Li + /Li ++ ) plays a significant role on the power balance. Calculations of the radiation losses are usually performed using a stationary collisional–radiative model, assuming constant values for the plasma parameters ( N e , T e ,…). Such an approach is not suitable for turbulent plasmas where the various parameters are time-dependent. This is critical especially for the edge region, where the fluctuation rates can reach several tens of percents [e.g. J.A. Boedo, J. Nucl. Mater. 390–391 (2009) 29–37]. In this work, the role of turbulence on the radiated power is investigated with a statistical formalism. A special emphasis is devoted to the role of temperature fluctuations, successively for low-frequency fluctuations and in the general case where the characteristic turbulence frequencies can be comparable to the collisional and radiative rates.