[en] In this paper a single-fluid, one-dimensional, time-dependent model of an unconfined plasma armature is discussed. The temporal evolution of the pressure and current density distributions is shown to be controlled by a combination of magnetic diffusion, shear, ablation, and magneto-acoustic wave propagation within the plasma. Different parameter regimes are explored, and the characteristic time constants and length scales are established for these various physical processes. It is shown that, when the plasma slip-velocity is low, the plasma may fragment or disperse by virtue of a diffusion-driven instability. Conversely, when ablation is high, and the slip-velocity is large, the plasma will form a parasitic current sheet at the tail of the armature, which may detach from the primary plasma. The first of these instabilities is initiated by a decrease in the input current. The second occurs above a certain critical combination of magnetic field strength and ablation coefficient

[en] Short communication

[en] Short communication

[en] Short communication

[en] Our primary thesis is that Ekman pumping is an essential component of many confined, MHD flows. It occurs whenever the axis of a forced, columnar vortex intersects a solid boundary. The weak recirculation associated with Ekman pumping is important for two reasons. First, the recirculation provides an efficient mechanism of removing the energy supplied by the Lorentz force, by flushing all streamlines through a boundary layer. Second, the Coriolis acceleration associated with the secondary flow can be used to balance the azimuthal component of the Lorentz force. We illustrate these points by looking at both axisymmetric cavity. Here we extend Davidson's (1992) model and compare its predictions with laboratory and numerical experiments. The experiments were performed in both cones and hemispheres and broadly support the model's predictions. In particular, they show the dominance of Ekman pumping and the resulting independence of angular momentum with depth. Next we note that axial symmetry, although mathematically convenient, is not a physical prerequisite for Ekman pumping. The same structure emerges in rectangular domains, and when the body force possesses no axial symmetry. We merely require that the axis of a vortex intersects with a solid boundary. This is illustrated through a sequence of numerical experiments of swirling flow in a rectangular box. (author). 20 refs., 9 figs

[en] We report for the first time two distinctive features in the odd–odd nucleus ¹²⁰I: a pair of doublet bands and a high-spin isomer built on the $\pi h_{11/2}\nu h_{11/2}$ configuration. For producing the excited states of ¹²⁰I, a fusion-evaporation reaction ¹¹⁸Sn(⁶Li, 4n) at E${}_{lab}=48$ MeV was employed. The beam was provided by the 14UD tandem accelerator of the Heavy Ion Accelerator Facility at the Australian National University. The observed doublet structure built on the positive-parity states is the first case and unique in isotopes with $Z=53$. The emerging properties are indicative of the known chiral characteristics, leading to a doubling of states for the $\pi h_{11/2}\nu h_{11/2}$ configuration. In contrast, the high-spin isomer with a half-life of 49(2) ns at spin-parity $J^{\pi }={25}^{+}$ can be explained in terms of a noncollective oblate structure with the full alignment of six valence nucleons outside the ¹¹⁴Sn core: three protons ${(g_{7/2})}^1{(d_{5/2})}^1{(h_{11/2})}^1$ and three neutrons ${(h_{11/2})}^3$. This is an outstanding case that reveals a pure single-particle structure consisting of equal numbers of valence protons and neutrons outside the semi-double shell closure of ¹¹⁴Sn with $Z=50$ and $N=64$.