Modelling laser-atom interactions in the strong field regime

We consider the ionisation of atomic hydrogen by a strong infrared field. We extend and study in more depth an existing semi-analytical model. Starting from the time-dependent Schroedinger equation in momentum space and in the velocity gauge we substitute the kernel of the non-local Coulomb potential by a sum of N separable potentials, each of them supporting one hydrogen bound state. This leads to a set of N coupled one-dimensional linear Volterra integral equations to solve. We analyze the gauge problem for the model, the different ways of generating the separable potentials and establish a clear link with the strong field approximation which turns out to be a limiting case of the present model. We calculate electron energy spectra as well as the time evolution of electron wave packets in momentum space. We compare and discuss the results obtained with the model and with the strong field approximation and examine in this context, the role of excited states.Comment: 11 pages, 5 figure

Strong field approximation within a Faddeev-like formalism for laser-matter interactions

We consider the interaction of atomic hydrogen with an intense laser field within the strong-field approximation. By using a Faddeev-like formalism, we introduce a new perturbative series in the binding potential of the atom. As a first test of this new approach, we calculate the electron energy spectrum in the very simple case of a photon energy higher than the ionisation potential. We show that by contrast to the standard perturbative series in the binding potential obtained within the strong field approximation, the first terms of the new series converge rapidly towards the results we get by solving the corresponding time-dependent Schroedinger equation.Comment: 7 pages, 1 figur

Guidance on a better integration of aquaculture, fisheries, and other activities in the coastal zone: from tools to practical examples

This guidance document provides a comprehensive assessment of the conflicts and synergies between fisheries, aquaculture and other activities in the coastal zone in six COEXIST case study areas. It forms deliverable D5.2 of the COEXIST project and synthesises deliverable D5.1, which provides a more detailed description of the methods used and results. This document also accounts for the views and expectations of stakeholders that were raised at the COEXIST stakeholder workshop held in Bergen, Norway, parallel to the ICES (International Council for the Exploration of the Sea) Annual Science Conference 2012. Over 30 stakeholders representing a variety of sectors, including aquaculture, fisheries, coastal zone management, tourism and energy, as well as 20 members from the COEXIST project and ICES representatives, attended this event. The stakeholders and COEXIST members were from Denmark, Finland, France, Germany, Ireland, Italy, Norway, Portugal, Spain, the Netherlands and the United Kingdom. The workshop aims were firstly to communicate the COEXIST project results and progress to stakeholders and the second major aim was to receive stakeholder feedback on the development of best practice guidance for spatial planning to integrate fisheries, aquaculture and further demands in the coastal zone