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Register a new userMAICRM : A general model for rapid simulation of hot dense plasmas
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We propose a general model, Multi-Average Ion Collisional-Radiative Model (MAICRM), to rapid simulate the ionization and population distributions of hot dense plasmas. In MAICRM, the orbital occupation numbers of ions at the same charge stage are averaged and determined by the excitation and de-excitation processes; the populations of the average ions are determined by the ionization and recombination processes with the fixed orbital average occupation numbers in each ion. The calculated mean ionizations and charge state distributions of MAICRM are in general agreement with the other theoretical and experimental results especially for the mid- and high-density plasmas. Since MAICRM considers more detailed transitions and ionization balances than the average atom model and is faster than DCA/SCA models, this model has the advantage to be combined into hydrodynamic simulations.
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This work is to continue the development of the general model, Multi-Average Ion Collisional-Radiative Model (MAICRM), to calculate the plasma spectral properties of hot dense plasmas. In this model, an average ion is used to characterize the average orbital occupations and the total populations of the configurations within a single charge state. The orbital occupations and population of the average ion are obtained by solving two sets of rate equations sequentially and iteratively. The calculated spectra of Xe and Au plasmas under different plasma conditions are in good agreement with the DCA/SCA calculations while the computational cost is much lower.
We study the dynamics of a supersonic molecular beam in a low-finesse optical cavity and demonstrate that most molecules in the beam can be decelerated to zero central velocity by the intracavity optical field in a process analogous to electrostatic Stark deceleration. We show that the rapid switching of the optical field for slowing the molecules is automatically generated by the cavity-induced dynamics. We further show that $sim1%$ of the molecules can be optically trapped at a few millikelvin in the same cavity.
We investigate the photo-doubleionization of $H_2$ molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasi-particle consisting of both electrons (i.e. the dielectron) does. The work highlights the fact that non-local effects are embedded everywhere in nature where many-particle processes are involved.
Ultracold quasineutral plasmas generated in the laboratory are generically inhomogeneous and ex- hibit small charge imbalances. As will be demonstrated, via a hydrodynamic theory as well as microscopic simulations, the latter lead to efficient energy absorption at the plasma boundary. This proposed edge-mode is shown to provide a unified explanation for observed absorption spectra measured in different experiments. Understanding the response of the electronic plasma compo- nent to weak external driving is essential since it grants experimental access to the density and temperature of ultracold plasmas.
Orbital-free molecular dynamics simulations are used to benchmark two popular models for hot dense plasmas: the one component plasma (OCP) and the Yukawa model. A unified concept emerges where an effective OCP (eOCP) is constructed from the short-range structure of the plasma. An unambiguous ionization and the screening length can be defined and used for a Yukawa system, which reproduces the long range structure with finite compressibility. Similarly, the dispersion relation of longitudinal waves is consistent with the screened model at vanishing wavenumber but merges with the OCP at high wavenumber. Additionally, the eOCP reproduces the overall relaxation timescales of the correlation functions associated with ionic motion. In the hot dense regime, this unified concept of eOCP can be fruitfully applied to deduce properties such as the equation of state, ionic transport coefficients, and the ion feature in x-ray Thomson scattering experiments.
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