We present nonlinear three-dimensional simulations of the stably-stratified portion of the solar tachocline in which the rotational shear is maintained by mechanical forcing. When a broad toroidal field profile is specified as an initial condition, a clam-shell instability ensues which is similar to the freely-evolving cases studied previously. After the initial nonlinear saturation, the residu...

Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator C-Mod Ohmic L-mode plasmas following electron density ramps. For low density discharges, the core rotation is directed cocurrent, and reverses to countercurrent following an increase in the density above a certain threshold. Such reversals occur together with a decrease in density fluctuations with 2 cm(-1...

We describe a generalization of the asymptotic calculation of the tidal torques experienced by a massive star as a result of a companion in circular orbit originally considered by Zahn (1975,1977) to the case of a rotating star when the forcing frequency is small and in the inertial regime, that is it is less than twice the rotation frequency in magnitude. The results confirm the presence of a ...

An analysis of the toroidal modes of a rotating fluid, by means of the differential equations of motion is not readily tractable. A matrix representation of the equations in a suitable basis, however, simplifies the problem considerably and reveals many of its intricacies. Let Ω be the angular velocity of the star and (l, m) be the two integers that specify a spherical harmonic function. One re...

An increase in ELM frequency has been demonstrated in MAST by applying resonant magnetic perturbations (RMPs) with toroidal mode number, nRMP = 2, 3, 4, 6. It has been observed that the mitigated ELM frequency increases with the amplitude of the applied field provided it is above a critical threshold. This threshold value depends on the mode number of the RMP, with higher nRMP having a larger c...

The Soft X-Ray (SXR) tomography system on the Madison Symmetric Torus uses four cameras to determine the emissivity structure of the plasma. This structure should directly correspond to the structure of the magnetic field; however, there is an apparent phase difference between the emissivity reconstructions and magnetic field reconstructions when using a cylindrical approximation. The differenc...

Lasing from an erbium-doped high-Q silica toroidal microcavity coupled to a tapered optical fiber is demonstrated and analyzed. Average erbium ion concentrations were in the range 0.009–0.09 at. %, and a threshold power as low as 4.5 mW and an output lasing power as high as 39.4 mW are obtained from toroidal cavities with major diameters in the range 25–80 mm. Controlling lasing wavelength in a...

Intrinsic steady state plasma rotation is important for plasma confinement in ITER, since the momentum input is expected to be small. It is well known that the intrinsicplasma rotation in stellarator is determined by non-ambipolar diffusion due to helical ripple [1]. The non-ambipolar diffusion due to small 3D magnetic perturbation described by theNeoclassical Toroidal plasma Viscosity ...

We analyze the stability and dynamics of toroidal liquid droplets. In addition to the Rayleigh instabilities akin to those of a cylindrical droplet there is a shrinking instability that is unique to the topology of the torus and dominates in the limit that the aspect ratio is near one (fat tori). We first find an analytic expression for the pressure distribution inside the droplet. We then dete...