Testing quantum mechanics in non-Minkowski space-time with high power lasers and 4th generation light sources

A common misperception of quantum gravity is that it requires accessing energies up to the Planck scale of 1019 GeV, which is unattainable from any conceivable particle collider. Thanks to the development of ultra-high intensity optical lasers, very large accelerations can be now the reached at their focal spot, thus mimicking, by virtue of the equivalence principle, a non Minkowski space-time. Here we derive a semiclassical extension of quantum mechanics that applies to different metrics, but under the assumption of weak gravity. We use our results to show that Thomson scattering of photons by uniformly accelerated electrons predicts an observable effect depending upon acceleration and local metric. In the laboratory frame, a broadening of the Thomson scattered x ray light from a fourth generation light source can be used to detect the modification of the metric associated to electrons accelerated in the field of a high power optical laser

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Strong coupling corrections in the analysis of x-ray Thomson scattering measurements

We present simplified expressions for the dynamic structure factor, or form factor S(k, omega), which is the quantity describing the inelastic x-ray scattering cross section from a dense plasma or a simple liquid. Our results, based on the random phase approximation (RPA) for the treatment on the charged particle coupling, are compared with analytical expressions for the free electron dynamic structure factor which include effects of strong coupling in both classical and degenerate plasmas. We will show that these modifications introduce minimal corrections to the RPA for typical conditions found in recent non-collective x-ray Thomson scattering experiment on solid density isochorically heated laser plasmas. On the other hand, strong collective scattering may exhibit significant deviations from the RPA. The results shown in this work can be applied to interpreting future x-ray scattering in warm dense plasmas occurring in inertial confinement fusion experiments or for the modelling of solid density matter found in the interior of planets

Generalized x-ray scattering cross section from nonequilibrium plasmas

We propose a modified x-ray form factor that describes the scattering cross section in warm dense matter valid for both the plasma and the solid (crystalline) state. Our model accounts for the effect of lattice correlations on the electron-electron dynamic structure, as well as provides a smooth transition between the solid and the plasma scattering cross sections. In addition, we generalize the expression of the dynamic structure in the case of a two-temperature system (with different electron and ion temperatures). This work provides a unified description of the x-ray scattering processes in warm and dense matter, as the one encountered in inertial confinement fusion, laboratory astrophysics, material science, and high-energy density physics and it can be used to verify temperature relaxation mechanisms in such environments

X-ray probe development for collective scattering measurements in dense plasmas

X-ray spectra and conversion efficiencies of the laser-produced chlorine Ly- α and K- α line radiation have been investigated to develop X-ray probes for the collective scattering regime. The Ly- α radiation was produced by either smoothed or un-smoothed laser beams with nanosecond-long laser pulses yielding high conversion efficiencies of up to 0.3% sufficient for X-ray scattering measurements. However, the time-integrated measurements show a significant dielectronic satellite emission on the red wing of the primary Ly- α line which must be avoided to resolve the plasmon feature in the scattering spectra. We find no red wing emission features for ultra-short pulse laser produced K-α radiation. The bandwidth of ΔE/E = 2 × 10-3 is suited for collective scattering, but the conversion efficiency falls short of the high values achieved for the Ly-α. These findings indicate that present laser-produced X-ray sources will restrict the choice of detectors and plasma conditions for collective X-ray scattering from dense plasmas

Limits on collective X-ray scattering imposed by coherence

We present the calculation of the threshold for observation of collective plasmon modes in a solid density plasma probed with a partially coherent X-ray source. We find that at lower electron densities (ne ≲ 2 × 1023 cm-3) de-coherence effects pose a stringent limit to the effective divergence as well as bandwidth of the probe source. These results are more restrictive than the usual condition that the probed scale-length must be larger than the screening distance in the plasma. © EDP Sciences

Theoretical model of x-ray scattering as a dense matter probe.

We present analytical expressions for the dynamic structure factor, or form factor S(k,omega), which is the quantity describing the x-ray cross section from a dense plasma or a simple liquid. Our results, based on the random phase approximation for the treatment on the charged particle coupling, can be applied to describe scattering from either weakly coupled classical plasmas or degenerate electron liquids. Our form factor correctly reproduces the Compton energy down-shift and the known Fermi-Dirac electron velocity distribution for S(k,omega) in the case of a cold degenerate plasma. The usual concept of scattering parameter is also reinterpreted for the degenerate case in order to include the effect of the Thomas-Fermi screening. The results shown in this work can be applied to interpreting x-ray scattering in warm dense plasmas occurring in inertial confinement fusion experiments or for the modeling of solid density matter found in the interior of planets

Direct observation of stimulated-Brillouin-scattering detuning by a velocity gradient.

We report the first direct evidence of detuning of stimulated Brillouin scattering (SBS) by a velocity gradient, which was achieved by directly measuring the frequency shift of the SBS-driven acoustic wave relative to the local resonant acoustic frequency. We show that in the expanding part of the plasma, ion-acoustic waves are driven off resonance which leads to the saturation of the SBS instability. These measurements are well reproduced by fluid simulations that include the measured flow

Derivation of the static structure factor in strongly coupled non-equilibrium plasmas for X-ray scattering studies

We present a fully analytical derivation of the static response function in strongly coupled and non-equilibrium plasmas. The model we are proposing is based on a linear response formalism coupled to a charged hard sphere reference for the ions. The electrons, instead, are treated using a local field correction which satisfies the compressibility sum rule at finite temperatures. The model is applied to calculate an effective ion mass that accounts for the self-energy correction of the free particle energy. We will discuss the implication of this approach in the interpretation of experimental results in X-ray scattering measurements from dense plasmas. © 2007 Elsevier B.V. All rights reserved

Demonstration of spectrally resolved x-ray scattering in dense plasmas.

We present the first spectrally resolved x-ray scattering measurements from solid-density plasmas. The scattering spectra show the broadened Compton down-shifted feature allowing us to determine the electron temperature and density with high accuracy. In the low temperature limit, our data indicate that the ionization balance reflects the electrons in the conduction band consistent with calculations that include quantum mechanical corrections to the interaction potential