Markets in defense of Europe: Providing public goods in European defense

The EU is not yet a defense public goods buyer, but it is generally a public goods provider in the form of the single market, which includes security goods. Public defense goods provision includes a functioning defense market, but the European market for defense equipment remains insufficiently integrated. EU regulation can reduce defense market uncertainty and incentivize R&D spending, ensuring future company competitiveness. The EU should expand its regulatory authority in defense and indirectly provide Europe with a defense market as a public good. Eventually, the EU should work toward consolidating demand and supply, which would further reduce inefficiencies and meet the challenge of secular rises in costs for defense

Modeling the response of mesospheric sodium to pulsed-laser excitation

A simulation modeling excitation of the sodium D-2 line by nanosecond time scale pulsed lasers is described. By numerically integrating transition rates in the sodium hyperfine structure, the return flux per sodium atom is predicted as a function of laser power. The simulation should be useful for studies of mesospheric sodium and adaptive optics. Applications include the estimation of sodium column density from lidar return flux, and of laser guide star brightness for different pulsed laser formats. The simulation assumes that the pulse repetition frequency is sufficiently low (smaller than a few kilohertz) that atomic collisions restore local thermodynamic equilibrium between pulses. It is also assumed that the pulse length is short compared to the Larmor precession time scale. The numerical results are well-approximated by a simple analytic model for a three-level atom. The number of emitted photons is found to be primarily dependent on the product of the length of the laser pulse and the energy density. (C) 2017 Optical Society of Americ