On the plasma quasineutrality under oscillatory confinement based on a nanosecond vacuum discharge

One of the main problems for inertial electrostatic confinement devices with electron injection is the space charge neutralization. This work is devoted to the analysis of the problem of plasma quasineutrality in the scheme of plasma oscillatory confinement based on nanosecond vacuum discharge (NVD). Electrodynamics modeling of the processes of aneutronic fusion of proton–boron showed that the plasma in the NVD, and especially on the discharge axis, really corresponds to a quasineutral regime, which is rather different from the well-known scheme of periodically oscillating plasma spheres (POPS). In this case, small oscillations in the NVD are a mechanism of resonant ion heating, unlike coherent compressions in the original POPS model. The scaling of the fusion power turns out to be close to the fusion scheme with POPS, but differs significantly in the values of the parameter of quasineutrality and the compression ratio.

Low Density Interior in Supercooled Aqueous Nanodroplets Expels Ions to the Subsurface

The location of a single and multiple ions in aqueous droplets plays a key role in chemical reactivity of atmospheric and man-made aerosols. We report direct computational evidence that in supercooled aqueous nanodroplets a lower density core of tetrahedrally coordinated water molecules expels the sodium ions to a higher density and more disordered subsurface. In contrast, at ambient temperature the single Na+ density is higher in the core region and has a broad maximum at the droplet's center of mass. We analyse the expulsion of a single ion in terms of a general reference electrostatic model that we have developed. The energy of the system in the analytical model is expressed as the sum of electrostatic and surface energy of a fluctuating droplet. The model predicts that the energy associated with the distance of the ion from the droplet's center of mass is quadratic in this distance. We name thiseffect "electrostatic confinement". The predictions of the model are consistent with the simulations fndings for a single Na+ ion at ambient conditions. Our results assist in understanding the mechanisms of charging of macromolecules in spray-based ionization methods used in native mass spectrometry and the physical chemistry of atmospheric aerosols.<br>

Low Density Interior in Supercooled Aqueous Nanodroplets Expels Ions to the Subsurface

The location of a single and multiple ions in aqueous droplets plays a key role in chemical reactivity of atmospheric and man-made aerosols. We report direct computational evidence that in supercooled aqueous nanodroplets a lower density core of tetrahedrally coordinated water molecules expels the sodium ions to a higher density and more disordered subsurface. In contrast, at ambient temperature the single Na+ density is higher in the core region and has a broad maximum at the droplet's center of mass. We analyse the expulsion of a single ion in terms of a general reference electrostatic model that we have developed. The energy of the system in the analytical model is expressed as the sum of electrostatic and surface energy of a fluctuating droplet. The model predicts that the energy associated with the distance of the ion from the droplet's center of mass is quadratic in this distance. We name thiseffect "electrostatic confinement". The predictions of the model are consistent with the simulations fndings for a single Na+ ion at ambient conditions. Our results assist in understanding the mechanisms of charging of macromolecules in spray-based ionization methods used in native mass spectrometry and the physical chemistry of atmospheric aerosols.<br>