Probing the quantum vacuum with ultra intense laser pulses

This article presents: 1) The theoretical background of strong field physics and vacuum structure and stability; 2) The instrumental developments in the area of pulse lasers and considers the physics case for ultra intense laser facilities; and 3) Discussion of the applied and fundamental uses of ultra-intense lasers.Comment: Contribution in Special Topics issue for IZEST, 12 pages incl 1 figure. Contains extended citation list compared to published versio

Fast ignition driven by quasi-monoenergetic ions: Optimal ion type and reduction of ignition energies with an ion beam array

Fast ignition of inertial fusion targets driven by quasi-monoenergetic ion beams is investigated by means of numerical simulations. Light and intermediate ions such as lithium, carbon, aluminium and vanadium have been considered. Simulations show that the minimum ignition energies of an ideal configuration of compressed Deuterium-Tritium are almost independent on the ion atomic number. However, they are obtained for increasing ion energies, which scale, approximately, as Z^2, where Z is the ion atomic number. Assuming that the ion beam can be focused into 10 {\mu}m spots, a new irradiation scheme is proposed to reduce the ignition energies. The combination of intermediate Z ions, such as 5.5 GeV vanadium, and the new irradiation scheme allows a reduction of the number of ions required for ignition by, roughly, three orders of magnitude when compared with the standard proton fast ignition scheme

Diskurskoalitionen in der Finanzmarktrettung: das Finanzmarktstabilisierungsgesetz

Das Finanzmarktstabilisierungsgesetz kann als eines der weitreichendsten Gesetze der jüngeren Geschichte der Bundesrepublik gelten. Dieses Gesetz, das die Grundlage der Rettungsaktionen definierte, gibt eine politische Richtung vor, die das Verhältnis von Staat und Markt neu zugunsten des Staates definiert, auf stärkere Kontrolle der Finanzmarktakteure setzt und gleichzeitig demokratische Kontrollmechanismen aufweicht. Um dieses Policy-Ergebnis zu erklären, untersucht der Artikel die Diskurskoalitionen, die sich in der Policy-Arena Finanzmarktrettung gebildet haben.The Financial Market Stabilization Act (Finanzmarktstabilisierungsgesetz) is one of the most far reaching legislative acts in recent German history. The act defines the base for the German initiatives to rescue financial markets. It stands for a new relation between state and market in favour of "more state", stricter rules for financial market actors but less democratic control of political action. To understand this policy result the article analyses the "discoursecoalitions"

Fast ignition of inertial fusion targets by laser-driven carbon beams

Two-dimensional simulations of ion beam driven fast ignition are presented. Ignition energies of protons with Maxwellian spectrum and carbon ions with quasimonoenergetic and Maxwellian energy distributions are evaluated. The effect of the coronal plasma surrounding the compressed deuterium-tritium is studied for three different fuel density distributions. It is found that quasi- monoenergetic ions have better coupling with the compressed deuterium-tritium and substantially lower ignition energies. Comparison of quasimonoenergetic carbon ions and relativistic electrons as ignitor beams shows similar laser energy requirements, provided that a laser to quasimonoenergetic carbon ion conversion efficiency around 10% can be achieved.Comment: 8 pages, 10 figures, published in Physics of Plasma

Laser-like X-ray Sources Based on Optical Reflection from Relativistic Electron Mirror

A novel scheme is proposed to generate uniform relativistic electron layers for coherent Thomson backscattering. A few-cycle laser pulse is used to produce the electron layer from an ultra-thin solid foil. The key element of the new scheme is an additional foil that reflects the drive laser pulse, but lets the electrons pass almost unperturbed. It is shown by analytic theory and by 2D-PIC simulation that the electrons, after interacting with both drive and reflected laser pulse, form a very uniform flyer freely cruising with high relativistic gamma-factor exactly in drive laser direction (no transverse momentum). It backscatters probe light with a full Doppler shift factor of 4*gamma^2. The reflectivity and its decay due to layer expansion is discussed.Comment: 5 pages, 3 figures, submitted, invited talk on the workshop of Frontiers in Intense Laser-Matter Interaction Theory, MPQ, March 1-3, 2010

Acceleration of heavy Ions to MeV/nucleon Energies by Ultrahigh-Intensity Lasers

In this thesis the acceleration of heavy ions to multi-MeV energies by means of a laser is demonstrated for the first time. Using an ultrahigh-intensity laser, with focal intensities exceeding 5 x 10^19 W/cm^2, the laser-plasma interaction becomes relativistic and a strong electron current is driven in laser direction. These relativistic electrons penetrate the target foil and set up a quasistatic electric field at the target rear surface. This field is of the order of TV/m and accelerated Fluorine ions to energies of 100 MeV, i.e. about 10 % light speed, within 300 fs. While a normal accelerator needs a distance of roughly 100 m to reach these energies, the laser-driven acceleration achieves this in about 10 microns. Within the scope of this work, a technique was developed to select a specific ion species. The energy spectra and charge state distributions of several different species were measured and used to analyze the acceleration mechanism. The measured results were than compared to computer simulations to gain detailed information on the strength and timescale of the accelerating fields.Im Rahmen dieser Arbeit konnte zum ersten Mal die Beschleunigung schwerer Ionen auf MeV/Nukleon Energien mittels eines Lasers demonstriert werden. Mit Hilfe eines Ultrahochintensitätslasers, mit mehr als 5 x 10^19 W/cm^2 fokussierter Intensität, werden relativistische Laser-Plasmen erzeugt, die Elektronenströme in Laserrichtung durch die Targetfolie hindurch treiben. Diese Ströme erzeugen ein quasistatisches Raumladungsfeld mit einer Stärke von einigen TV/m, welches in nur 300 fs Fluorionen auf über 100 MeV (ca. 10 % Lichtgeschwindigkeit) beschleunigt. Während ein konventioneller Beschleuniger dafür ca. 100 m Strecke benötigt, reichen im Laserplasma ca. 10 Mikrometer. Ausserdem wurde im Rahmen dieser Arbeit eine Technik entwickelt, die es erlaubt, beliebige Ionensorten gezielt zu beschleunigen. Durch Messung der Energiespektren und Ladungszustandsverteilungen und Vergleich derselben mit Computersimulationen konnten detaillierte Informationen über die Physik des Beschleunigungsmechanismus gewonnen werden

En-route to the fission-fusion reaction mechanism: a status update on laser-driven heavy ion acceleration

The fission-fusion reaction mechanism was proposed in order to generate extremely neutron-rich nuclei close to the waiting point N = 126 of the rapid neutron capture nucleosynthesis process (r-process). The production of such isotopes and the measurement of their nuclear properties would fundamentally help to increase the understanding of the nucleosynthesis of the heaviest elements in the universe. Major prerequisite for the realization of this new reaction scheme is the development of laser-based acceleration of ultra-dense heavy ion bunches in the mass range of A = 200 and above. In this paper, we review the status of laser-driven heavy ion acceleration in the light of the fission-fusion reaction mechanism. We present results from our latest experiment on heavy ion acceleration, including a new milestone with laser-accelerated heavy ion energies exceeding 5 MeV/u