Ions In Regime Research Articles

Effects observed in numerical simulation of high-beta plasma with hot ions in an axisymmetric mirror machine

We present the results of numerical simulation by two-dimensional hybrid particle-in-cell code of high-beta plasma with hot ions in an axisymmetric mirror machine. Two particular effects are discussed: the self-rotating of plasma with Maxwellian ions in regime of diamagnetic confinement and the excitation of axisymmetric magnetosonic waves in a high-beta plasma with sloshing ions.

Magnetized wake driven anomalous diffusion in complex plasma

Diffusion of a three-dimensional dust ensemble embedded in a flowing plasma in the presence of a moderate magnetic field is investigated using Langevin dynamics simulation. It is found that the asymmetric wake potential created due to streaming ions drive the dusty plasma from the subdiffusive to the superdiffusive regime. A novel wake dominant regime is identified that shows superdiffusive behavior for suitable adjustment of the magnetic field. The dependence of the cross field diffusion coefficient on the magnetic field exhibits three distinct behaviors characterized by (a) B2−3 for an ultra-low magnetic field and strongly correlated state, (b) B≃0.1 for a moderate magnetic field, and (c) classical B−2 for a relatively large magnetic field. Our analysis shows that the magnetic field is mediated via the streaming ions in regimes (a) and (b) of relatively low magnetic field where the dependence of the diffusion coefficient on the magnetic field is faster than the usual classical regime.

Energy distributions of superthermal ions in regime with sawtooth oscillations during neutral beam injection at the Globus-M tokamak

Specific features of the energy distributions of fast ions during neutral beam injection at the Globus-М tokamak are considered. Different loss mechanisms that can lead to the formation of a specific shape of the energy spectrum of superthermal ions are analyzed. The effect of sawtooth oscillations on the loss of fast ions is discussed.

FTICR analysis of the magnetic trapping mode of the electron beam ion trap

An electron beam ion trap is used to produce and confine highly-charged atomic ions in an energetic electron beam (electron trapping mode). After switching off the electron beam the ions remain trapped due to the external magnetic and electric fields. We have investigated the properties of this magnetic trapping mode by use of Fourier transform ion cyclotron resonance mass spectrometry. We found that the number of highly charged ions and the relative species abundance is nearly the same just before and just after turning off the electron beam. The electron trapping mode thus represents an ideal method for filling the trap in situ without the losses associated with transferring the ions from external sources. About 10 5 ions per highly charged species, such as 84Kr 35+, were shown to exist in the trap in the magnetic trapping mode. A lower limit of 1.5 s was placed on the ion confinement time. This length is sufficient for a multitude of experiments which may be carried out in the future and which are impossible in the presence of an electron beam. The magnetic trapping mode thus represents a new opportunity for studying the physics of highly charged ions in regimes that have been previously inaccessible.