相关论文: Nonequilibrium ionization and ambipolar diffusion …
The thermal structure of the chromosphere is regulated through a complex interaction of various heating processes, radiative cooling, and the ionization degree of the plasma. Here we study the impact on the thermal properties of the…
The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only…
The ionization of hydrogen in the solar chromosphere and transition region does not obey LTE or instantaneous statistical equilibrium because the timescale is long compared with important hydrodynamical timescales, especially of…
The solar chromosphere is weakly ionized and interactions between ionized particles and neutral particles likely have significant consequences for the thermodynamics of the plasma. We investigate the importance of introducing neutral…
The heating of the chromosphere in internetwork regions remains one of the foremost open questions in solar physics. In the present study we tackle this old problem by using a very high spatial-resolution simulation of quiet-Sun conditions…
We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion-neutral…
During transient events such as major solar eruptions, the plasma can be far from the equilibrium ionization state because of rapid heating or cooling. Non-equilibrium ionization~(NEI) is important in rapidly evolving systems where the…
Solar partially ionized plasma is frequently modeled using single-fluid (1F) or two-fluid (2F) approaches. In the 1F case, charge-neutral interactions are often described through ambipolar diffusion, while the 2F model fully considers…
Turbulence is often invoked to explain the origin of nonthermal particles in space and astrophysical plasmas. By means of 3D fully kinetic particle-in-cell simulations, we demonstrate that turbulence in low-$\beta$ plasmas ($\beta$ is the…
Magnetic fields play a role in the dynamics of many astrophysical processes, but they are hard to detect. In a partially ionized plasma, a magnetic field works directly on the ionized medium but not on the neutral medium, which gives rise…
Detailed numerical models of chromosphere and corona are required to understand the heating of the solar atmosphere. An accurate treatment of the solar chromosphere is complicated by the effects arising from Non Local Thermodynamic…
The solar ultraviolet intensities of spectral lines originating from Li- and Na-like ions have been observed to surpass the expectations derived from plasmas with coronal approximation. The violation of the coronal approximation can be…
Understanding the dynamics of the solar chromosphere is crucial to understanding energy transport across the solar atmosphere. The chromosphere is optically thick at many wavelengths and described by non-local thermodynamic equilibrium…
The ambipolar diffusion approximation is used to model partially ionised plasma dynamics in a single fluid setting. To correctly apply the commonly used version of ambipolar diffusion, a set of criteria should be satisfied including the…
We present results of 2.5D numerical simulations of the emergence of sub-surface magnetic flux into the solar atmosphere, with emerging flux regions ranging from $10^{18}$ to $10^{21}$ Mx, representing both ephemeral and active regions. We…
Magnetohydrodynamic (MHD) simulations of the solar atmosphere are often performed under the assumption that the plasma is fully ionized. However, in the lower solar atmosphere a reduced temperature often results in only the partial…
Thermal nonequilibrium (TNE) is a condition of the plasma in the solar corona in which the local rate of energy loss due to radiation increases to the point that it cannot be sustained by the various heating terms acting on the plasma,…
A flux rope eruption on September 10, 2017 provides unique observations of the plasma sheet beneath the rising flux rope. The plasma sheet is likely in a nonequilibrium state in terms of both ionization and the electron distribution…
We have performed 3-D numerical simulations to investigate the effect of partial ionization on the process of magnetic flux emergence. In our study, we have modified the single-fluid MHD equations to include the presence of neutrals and…
Thermal non-equilibrium (TNE) is a fascinating situation that occurs in coronal magnetic flux tubes (loops) for which no solution to the steady-state fluid equations exists. The plasma is constantly evolving even though the heating that…