On the Frequency Drift of Coronal Loop’s Fast Kink Oscillation: Effects of Quasi-static Evolution in Loop Density

Although the fast kink oscillation, as one of a few fundamental modes in coronal seismology, has received a lot of attention over the past two decades, observations of its frequency drift remain elusive. There is evidence that this phenomenon is related to the quasi-static evolution of loop density. We therefore consider analytically the effects of a quasi-static density evolution on the fast kink oscillation of coronal loops. From the analyses, we determine explicitly the analytic dependence of the oscillation period/frequency and amplitude on the evolving density of the oscillatory loop. The findings can well reconcile several key characters in some frequency drift observations, which are not understood. Models of fast kink oscillation in the thermal dynamic loop are also established to investigate the present effects in more detail. Our findings not only show us a possible explanation for the frequency drift of the coronal loop’s fast kink oscillation, but also a full new energy transformation mechanism where the internal energy and the kinetic energy of an oscillating coronal loop can be interchanged directly by the interaction of the loop’s oscillation and its density evolution, which we suggest may provide a new clue for the energy processes associated with a thermodynamic resonator in the space magnetic plasma.

Absorption Enhancement in Hyperbolic Metamaterials by Means of Magnetic Plasma

The main features of surface plasmon polaritons (SPPs) that can propagate in a metamaterial–magnetic plasma structure are studied from theoretical perspectives. Both the conventional and imaginary parts of the dispersion relation of SPPs are demonstrated considering transverse magnetic (TM) polarization. We examine and discuss the influence of the external magnetic field. The results demonstrate that this factor dramatically alters the nature of SPPs. It is concluded that the positions and propagation lengths of SPPs can be engineered. Moreover, we present an approach allowing for an absorption enhancement that is a pivotal factor in antenna design. A unified insight into the practical methods aiming to attain hyperbolic dispersion by means of nanostructured and nanowire metamaterials is demonstrated.

The PANDORA project: an experimental setup for measuring in-plasma β-decays of astrophysical interest

Experiments performed on Storage Rings have shown that lifetimes of beta-radionuclides can change dramatically as a function of theionization state. PANDORA (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) aims at measuring, for the first time, nuclear β-decay rates in stellar-like conditions, especially for radionuclides involved in nuclear-astrophysics processes (BBN, s- processing, CosmoChronometers, Early Solar System formation). Compact magnetic plasma traps, where plasmas reach density ne~10n-1014 cm-3, and temperature Te~0.1-30 keV, are suitable for such studies. The decay rates can be measured as a function of the charge state distribution of the inplasma ions. The collaboration is now designing the plasma trap able to reach the needed plasma densities, temperatures and charge states distributions. A first list of radioisotopes, including tens of physics cases of potential interest is now available. Possible physics cases include, among the others, 2°4Tl, 63Ni, 6°Co, 171Tm, 147Pm, 85Kr, 176Lu and the pairs 187Re-187Os and 87Sr-87Rb, which play a crucial role as cosmo-clock. Physics cases are now under evaluation in terms of lifetime measurements feasibility in a plasma trap.

Study of the Absorption Properties of Terahertz Wave in the Plasma Medium

In this article, we study about the absorption properties of terahertz (THz) wave in the magnetic plasma medium. Terahertz wave has strong transmission in plasma. Generally speaking, with the increase in THz wave frequency, the transmission in plasma is stronger. Thus, we can consider raising carrier frequency to THz band to solve the communication of “blackout.” We found that the absorption in magnetic plasma is greatly affected by magnetic field. The changes on the power absorption coefficient of the two kinds of eigen wave in magnetic plasma vary with how the outside magnetic field, incident angle, and the thickness of the plasma are obtained. The study found that following the increase in magnetic field, the absorption of left circularly polarised waves (L-wave) gradually reduces, and the right circularly polarised waves (R-wave) will produce two absorption peaks, and these two absorption peaks move to high frequency as a whole. With the increase in incident angle and the high spectrum absorption of L-wave enhancement, the reflection between the two absorption peaks of R-wave broadens. The reflection area on the left side of the low-frequency area to absorb has a little change. The absorption on the right side of the high-frequency area is enhancement. With the increase in the plasma thickness, the L-wave absorption peak on the right side of the high-frequency area absorbs enhancement; the R-wave reflection between the two absorption peak areas is impregnability, the second absorption peak absorption enhancement on the right side of the high-frequency area. The study has shown the different absorption mechanisms of the L-wave and the R-wave and shown different absorption features in magnetic plasma.