A Review of Observations of Molecular Ions in the Earth’s Magnetosphere-Ionosphere System

Ionospheric molecular ions, such as NO+, N2+ and O2+, are gravitationally bound, and are expected to undergo recombination to form a pair of neutral atoms, due to short dissociative recombination lifetime. Therefore, they are expected to be relatively cold in the Earth’s atmosphere, compared with light ions such as H+ and He+, or even heavier ions such as N+ or O+. However, several spacecraft missions observed their presence in the high-altitude ionosphere and the magnetosphere, predominantly during the geomagnetically active times. This hints to the possibility that molecular ions have the ability to acquire sufficient energy in a very short time, and can be used as tracers of mass differentiated vertical transport to understand the mechanisms responsible for “fast ionospheric outflow” and, In this letter, we review the observational data sets that reported on the abundances of molecular ions in the Earth’s magnetosphere-ionosphere system, starting from their first observations by the Sputnik III mission, to the current Arase (ERG) satellite and Enhanced Polar Outflow Probe (e-POP) missions. The available data suggests that molecular ions are quite abundant in the lower atmosphere at all times, but are only seen in the high-altitude ionosphere and magnetosphere during the times of increased geomagnetic activity.

Nd L-shell x-ray emission induced by light ions

The L-shell x ray of Nd has been obtained for 300 - 600 keV He2 + ions impacting, and compared with that produced by H+ and H2 + ions. The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified in the energy region of about 300 - 400 keV. It is found that the energy of the distinct L-subshell x rays has a blue shift. The relative intensity ratios of Lβ1, 3, 4 and Lβ2, 15 to Lα1, 2 x-ray are enlarged compared to the atomic data, and they decrease with the increase of incident energy, and increase with increasing effective nuclear charge of the incident ions. That is interpreted by the multiple ionization of outer-shells induced by light ions.

Study of ion separation mechanism in the multi-component vacuum arc discharge

The separation phenomenon of light and heavy ions was widely observed experimentally in the vacuum arc discharge with multi-component composite cathode. In this work, a two-dimensional axisymmetric multi-fluid model is used to study the separation mechanism in the multi-component composite cathode vacuum arc. The multi-component vacuum arcs are simulated as a whole which includes separate cathode spot jets, the mixing region, and common arc column. The results show that the plasma jets originated from the separate cathode spot mix together to form a common arc column after a certain distance from the cathode. Due to the rapid increase of ion temperature dozens of times in mixing region of cathode spot jet, the effect of pressure gradient becomes far greater than that of the collisions between light and heavy ions. This leads to a shift in the predominant ion motion mechanism from ion-ion collision (single cathode spot jet region) to pressure expansion (the mixing region). Finally, the light ions gain higher velocities under pressure expansion. In addition, the effect of thermal conductivity and viscosity leads to the wider high temperature regions for light ions, thus making a wider distribution of corresponding ion flux. The numerical results are qualitatively consistent with the experimental results. This paper provides an insight into ion separation mechanism in the multi-component vacuum arc.

General principles for describing electronic and proton multiple scattering processes in solids

Analytical solution for the reflected light ions Pass Length Distribution Function (PLDF) equation is obtained. Reflected ions energy spectra calculated on the basis of the developed method shows satisfactory agreement with experimental data. The effectiveness of the developed methodology in the procedure for verifying the stopping power value is indicated.

Laser–Accelerated Plasma–Propulsion System

In this paper, the laser-accelerated plasma–propulsion system (LAPPS) for a spacecraft is revisited. Starting from the general properties of relativistic propellants, the relations between specific impulse, engine thrust and rocket dynamics have been obtained. The specific impulse is defined in terms of the relativistic velocity of the propellant using the Walter’s parameterization, which is a suitable and general formalism for closed–cycle engines. Finally, the laser-driven acceleration of light ions via Target Normal Sheath Acceleration (TNSA) is discussed as a thruster. We find that LAPPS is capable of an impressive specific impulse Isp in the 105 s range for a laser intensity I0≃1021W/cm2. The limit of Isp≲104 s, which characterizes most of the other plasma-based space electric propulsion systems, can be obtained with a relatively low laser intensity of I0≳1019W/cm2. Finally, at fixed laser energy, the engine thrust can be larger by a factor 102 with respect to previous estimates, making the LAPPS potentially capable of thrust-power ratios in the N/MW range.

Directional dependency of electronic stopping in nickel, projectile’s excited charge state and momentum transfer

We studied the directional dependency of electronic stopping power of swift light ions in nickel using real-time time-dependent density functional theory. We report a variation of electronic stopping for moving ions as the projectile probes different electronic densities of the host material. These results show that while the predicted magnitude stays in reasonable agreement with experiment, for $$v > 2$$ v > 2 . a.u. simulating only low index crystallographic directions is not enough to sample the experimental average values. The ab initio simulations give us access to microscopic quantities, such as non-adiabatic forces, momentum transfer and transient excited state charges of the projectile and host ions, which are not available through other methods. We report these quantities for the first time.

Description of (Hyper-)Fragments in Hadron-Induced Reactions

In this article we review the important role of non-equilibrium dynamics in reactions induced by ions and hadron beams to understand the fragmentation processes inside hadronic media. We discuss the single-particle dynamics in specific sources such as spectators in heavy-ion collisions and residual nuclear targets in hadron-induced reactions. Particular attention is given to the dynamics of hyperons. We further discuss the question regarding the onset of local instabilities, which are relevant for the appearance of fragmentation phenomena in nuclear reactions. We apply the theoretical formalism, that is, semi-classical transport embedded with statistical methods of nuclear fragmentation, to reactions induced by light ions and hadron beams. We discuss the results of nuclear fragmentation and, in particular, examine the formation of hypernuclei. Such studies are important for obtaining a deeper understanding of the equation of state in fragmenting matter and are relevant for forthcoming experiments, such as PANDA at FAIR and J-PARC in Japan.

Calculation of the sputtering coefficients of oxide films from the surface of a homogeneous material by medium-energy helium ions

The paper presents an analytical model for sputtering two-component layered inhomogeneous targets by bombardment with light ions. An analytical formula is obtained that makes it possible to calculate the total and partial sputtering yields of a binary layer of target inhomogeneity by light ions. The obtained formula is used to calculate the sputtering yields of oxide layers from the surface of a homogeneous substrate. The calculation results are in good agreement with the computer simulation data.

Electrostatic Ion-Acoustic Shock Waves in a Magnetized Degenerate Quantum Plasma

A theoretical investigation has been carried out to examine the ion-acoustic shock waves (IASHWs) in a magnetized degenerate quantum plasma system containing inertialess ultra-relativistically degenerate electrons, and inertial non-relativistic positively charged heavy and light ions. The Burgers equation is derived by employing the reductive perturbation method. It can be seen that under the consideration of non-relativistic positively charged heavy and light ions, the plasma model only supports the positive electrostatic shock structure. It is also observed that the charge state and number density of the non-relativistic heavy and light ions enhance the amplitude of IASHWs, and the steepness of the shock profile is decreased with ion kinematic viscosity. The findings of our present investigation will be helpful in understanding the nonlinear propagation of IASHWs in white dwarfs and neutron stars.