相关论文: Numerical Study of Evaporative Cooling in the Spac…
The expansion of ultracold neutral plasmas (UCP) is driven primarily by the thermal pressure of the electron component and is therefore sensitive to the electron temperature. At lower densities (less than 10$^8$ /cm$^3$), evaporative…
Recent simulations of self-gravitating accretion discs, carried out using a three-dimensional Smoothed Particle Hydrodynamics (SPH) code by Meru and Bate, have been interpreted as implying that three-dimensional global discs fragment much…
The aim of this paper is the modeling and simulation of impact of space radiation variability on total dose and single event effects in spaceborne electronics. It has been shown that the simultaneous thermal annealing may lead to…
The process of numerical thermalization in particle-in-cell (PIC) simulations has been studied extensively. It is analogous to Coulomb collisions in real plasmas, causing particle velocity distributions (VDFs) to evolve towards a Maxwellian…
We report here the experimental realization of multi-step cooling of a quantum system via heat-bath algorithmic cooling. The experiment was carried out using nuclear magnetic resonance (NMR) of a solid-state ensemble three-qubit system.
We examine heating and cooling in protostellar disks using 3-D radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized…
We describe the realization of a magnetically guided beam of cold rubidium atoms, with a flux of $7\times 10^9$ atoms/s, a temperature of 400 $\mu$K and a mean velocity of 1 m/s. The rate of elastic collisions within the beam is sufficient…
We elucidate the interplay between Newtonian thermal relaxation and numerical dissipation, of several different origins, in flow simulations of hot extrasolar planet atmospheres. Currently, a large range of Newtonian relaxation, or…
A new simulation approach of field evaporation is presented. The model combines classical electrostatics with molecular dynamics (MD) simulations. Unlike previous atomic-level simulation approaches, our method does not rely on an…
We present a theoretical analysis of the evaporative cooling of a magnetically guided atomic beam by means of discrete radio-frequency antennas. First we derive the changes in flux and temperature, as well as in collision rate and…
Hydrodynamical simulations of star formation have stimulated a need to develop fast and robust algorithms for evaluating radiative cooling. Here we undertake a critical evaluation of what is currently a popular method for prescribing…
Context. The level of porosity of interstellar ices - largely comprised of amorphous solid water (ASW) - contains clues on the trapping capacity of other volatile species and determines the surface accessibility that is needed for solid…
We theoretically analyze the cooling dynamics of an atom which is tightly trapped inside a high-finesse optical resonator. Cooling is achieved by suitably tailored scattering processes, in which the atomic dipole transition either scatters…
We extend an earlier semiclassical model to describe the dissipative motion of N atoms coupled to M modes inside a coherently driven high-finesse cavity. The description includes momentum diffusion via spontaneous emission and cavity decay.…
We experimentally study the dynamics of a degenerate one-dimensional Bose gas that is subject to a continuous outcoupling of atoms. Although standard evaporative cooling is rendered ineffective by the absence of thermalizing collisions in…
In this paper, the effect of self-gravity on the protoplanetary discs is investigated. The mechanisms of angular momentum transport and energy dissipation are assumed to be the viscosity due to turbulence in the accretion disc. The energy…
A new global analytical model of the heat dissipation process that occurs in passively-cooled embedded systems is introduced, and we explicit under what circumstances the traditional assumption that exponential cooling laws apply in such…
We demonstrate feedback cooling of the motion of a single rubidium atom trapped in a high-finesse optical resonator to a temperature of about 160 \mu K. Time-dependent transmission and intensity-correlation measurements prove the reduction…
Radiation transport plays important roles in stellar atmospheres, but the effects of turbulence are being obscured by other effects such as stratification. Using radiative hydrodynamic simulations of forced turbulence, we determine the…
The nature of freezing and melting transitions for a system of hard disks in a spatially periodic external potential is studied using extensive Monte Carlo simulations. Detailed finite size scaling analysis of various thermodynamic…