## About

19

Publications

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Introduction

**Skills and Expertise**

## Publications

Publications (19)

We describe the finite volume formulation of a miscible multi-fluid Euler model implemented in the code LERNA. Within this model, N single-fluid sets of Euler equations (mass, momentum and energy) are coupled together through source terms accounting for relaxation processes and leading to velocity and temperature equilibration. The equation of stat...

We present the results of the first Charged-Particle Transport Coefficient Code Comparison Workshop, which was held in Albuquerque, NM October 4–6, 2016. In this first workshop, scientists from eight institutions and four countries gathered to compare calculations of transport coefficients including thermal and electrical conduction, electron–ion c...

Computational models are formulated in hierarchies of variable fidelity, often with no quantitative rule for defining the fidelity boundaries. We have constructed a dataset from a wide range of atomistic computational models to reveal the accuracy boundary between higher-fidelity models and a simple, lower-fidelity model. The symbolic decision boun...

We have developed a concurrent heterogeneous multiscale method (HMM) framework with a microscale molecular dynamics (MD) model and a macroscale kinetic Vlasov-BGK model. The kinetic model is formulated such that BGK collision times are the closure data obtained from MD. Using the H-theorem, we develop the mathematical link between the MD and the ki...

We present the results of the first Charged-Particle Transport Coefficient Code Comparison Workshop, which was held in Albuquerque, NM October 4-6, 2016. In this first workshop, scientists from eight institutions and four countries gathered to compare calculations of transport coefficients including thermal and electrical conduction, electron-ion c...

The impact of collisionality and the range of the interparticle interaction on the bump-on-tail instability is examined both computationally and theoretically. Using three-dimensional, nonequilibrium molecular dynamics with a force law that varies continuously from long range (pure 1/r Coulomb limit) to short range and across coupling regimes from...

Particle-level simulations of shocked plasmas are carried out to examine kinetic properties not captured by hydrodynamic models. In particular, molecular dynamics simulations of 2D Yukawa plasmas with variable couplings and screening lengths are used to examine shock features unique to plasmas, including the presence of dispersive shock structures...

The velocity of a molecule evaporated from a mass-selected protonated water nanodroplet is measured by velocity map imaging in combination with a recently developed mass spectrometry technique. The measured velocity distributions allow probing statistical energy redistribution in ultimately small water nanodroplets after ultrafast electronic excita...

The sticking cross sections of water molecules on cold size-selected water clusters have been simulated using classical and quantum (path-integral) molecular dynamics trajectories under realistic conditions. The integrated cross sections for charged clusters show significant size effects with comparable trends as in experiments, as well as essentia...

A classical Molecular Dynamics code has been developed to simulate dense plasmas i.e. neutral systems of interacting ions and electrons. Our goal is to design a tool that relies on a reduced set of microscopic mechanisms in order to obtain solutions of complex time dependent n-body problems and to allow an efficient description of the plasma states...

Infrared spectra in the gas phase are experimentally obtained from the depletion signal after exposure to a laser field. This work aims to model such a dissociation probability for the (H2O)20H3O+ cluster, and compare it to the more conventional linear absorption spectrum. Using a flexible, polarisable but non-reactive potential, the response of th...

While the linear radiofrequency trap finds various applications in
high-precision spectroscopy and quantum information, its higher-order
cousin, the linear multipole trap, is almost exclusively employed in
physical chemistry. Recently, first experiments have shown interesting
features by laser-cooling multipole-trapped ion clouds. Multipole traps
s...

We report one-dimensional pinning of a single ion by an optical lattice. A standing-wave cavity produces the lattice potential along the rf-field-free axis of a linear Paul trap. The ion's localization is detected by measuring its fluorescence when excited by standing-wave fields with the same period, but different spatial phases. The experiments a...

A small number of laser-cooled ions trapped in a linear radiofrequency
multipole trap forms a hollow tube structure. We have studied, by means of
molecular dynamics simulations, the structural transition from a double ring to
a single ring of ions. We show that the single-ring configuration has the
advantage to inhibit the thermal transfer from the...

General Relativity formulated with Noncommutative geometry allows one to
obtain, via the fluctuation of Dirac operator, an exact equivalence principle:
generation of curvature and torsion from flat space. The fluctuation method
presented in this report is applied on two examples.

Ion traps, using radio-frequency (rf) electric fields, offer the possibility to store ion ensembles in a small region of space where, by means of cooling technics, their temperature can be reduced to some tenth of millikelvin. The aim of the work presented in this thesis is to theoretically study some aspects of the dynamics of trapped ions under D...

Additional radio-frequency (rf) potentials applied to linear multipole traps
create extra field nodes in the radial plane which allow one to confine single
ions, or strings of ions, in totally rf field-free regions. The number of nodes
depends on the order of the applied multipole potentials and their relative
distance can be easily tuned by the am...

We analyse the possibility of cooling ions with a single laser beam, due to the coupling between the three components of their motion induced by the Coulomb interaction. For this purpose, we numerically study the dynamics of ion clouds of up to 140 particles, trapped in a linear quadrupole potential and cooled with a laser beam propagating in the r...

A ring crystal of ions trapped in a linear multipole trap is studied as a
basis for an optical frequency standard. The equilibrium conditions and cooling
possibilities are discussed through an analytical model and molecular dynamics
simulations. A configuration which reduces the frequency sensitivity to the
fluctuations of the number of trapped ion...

## Projects

Project (1)