Current drive by fast magnetosonic waves is successfully performed in the JIPP T-IIU tokamak by means of a four-element dipole antenna array with a Faraday shield. A plasma current of about 50 kA is sustained by an rf power of about 80 kW in a low-density plasma (3 × ${10}^{12}$ ${\mathrm{cm}}^{-3\mathrm{}}$) with an efficiency comparable to that of slow-wave current drive. A density limit for fast magnetosonic current drive is observed, contrary to theoretical expectations based on linear wave propagation.

Nonclassical diffusion of test electrons was directly observed in a tokamak by examination of the radial broadening of their drift orbits. A strong correlation between this enhanced diffusion and small-scale radial magnetic field fluctuations of high poloidal mode number was found. The origin of these magnetic fluctuations is discussed in terms of microtearing mode.

The implosions of thin-walled, large-diameter, deuterium-tritium-filled glass microballoon targets ablatively driven by the 351-nm, 2-kJ OMEGA laser are reported. Compressed-fuel diagnostics, including the first direct simultaneous measurements of the fuel and shell areal densities, and detailed hydrodynamic simulations determine the effect of illumination uniformity on implosion symmetry.

The observation of very-low-frequency bands by Raman scattering in a nucleated cordierite glass is described. The frequency of the maximum of scattering is proportional to the inverse diameter of the particles, which are spherical spinel microcrystallites. It is shown that vibrational surface modes of particles are responsible for this Raman scattering.

A nematic liquid crystal should present an order electric polarization associated with the gradient of order parameter, in addition to the flexoelectric polarization associated with the gradient of orientation. Using thermodynamical arguments, we show that the order-electricity coefficients are of the same order as the flexoelectric ones. The dielectric energy resulting from the order polarization can explain the unsolved problem of the spontaneous titled orientation at the nematic-isotropic (or air) interfaces. The core of disclination lines can also present electric multipoles.

A decagonal quasicrystal with point group 10/mmm has been found in Al-14-at.%-Fe alloy. Zone-axis patterns of the decagonal phase appearing at the icosahedral positions are reminiscent of the appropriate icosahedral patterns. The symmetry and the angular separation of the zone axes can be obtained from the icosahedral phase by the addition of a mirror plane normal to a fivefold axis. This is supported by the observed diffuse streaking parallel to the tenfold axis. A similar decagonal phase in Al-20-at.%-Mn alloy reported by Bendersky can likewise be explained by the addition of mirror planes intersecting a fivefold axis of the icosahedral phase.

The dispersion of the vibrational modes of the $\frac{p(2\mathrm{}\times 2)\mathrm{O}}{\mathrm{Pt}\mathrm{}\left(111\right)\mathrm{}}$ system has been measured by inelastic He scattering along the $\overline{\Gamma }\overline{M}$ azimuth. The experimental results show the first direct evidence for the appearance of an energy gap in the Rayleigh curve at the $p(2\mathrm{}\times 2)$ reduced-zone boundary. Both the size of the gap (∼ 0.85 meV) and the appearance of a new mode near the $\overline{\Gamma }$ point are reproduced by a lattice-dynamical analysis, if three-body interactions of the bond-stretching type are included in the calculations.

We define a set of generalized symmetries for quasicrystals and find that this leads naturally to the operators which generate scale transformations ("inflations"). Our methods are applied to 2D fivefold-symmetric patterns, but generalize to other point groups and dimensions.

A stacking transformation with unusual structural and thermal hysteresis is reported in stage-2 alkali-metal-intercalated graphites. A sequence of 1D higher-order commensurate phases appears to form a stepwise-continuous pathway between fcc and hcp intercalant structures as the temperature is increased. The presence of correlated impurities, in the form of disordered in-plane domain walls, can account for instabilities in the sequence of transitions in support of recent theories of long-period-modulated materials.

Extended x-ray-absorption fine structure has been used in conjunction with the aggregation technique to investigate the structure of copper microclusters (7 to 15 Å mean diameter). The crystallographic structure of the microclusters is consistent with an fcc lattice. A small contraction of the nearest-neighbor distance was measured as a function of cluster size.

Values of the reduction in swelling of a single coil in a poor solvent are calculated for the continuous-polymer model, by use of the renormalized theory. These values are compared to light-scattering measurements of Perzynski, Adam, and Delsanti. The results support recent theoretical studies of anomalous effects associated with the tricritical state of a polymer chain and ultraviolet divergences. In fact, this comparison provides the first experimental evidence of the existence of a tricritical state for polymers near the $\theta$ temperature.

We derive a Diophantine equation for the Hall conductance of $N$ interacting electrons moving on a torus. The equation holds for general background fields, including inhomogeneous magnetic fields, and random substrates, but is effective when combined with symmetries. For example, together with translation invariance in one direction it determines the Hall conductance uniquely and constrains the degeneracy and crossings of eigenvalues.

A density-functional-based theory is developed for calculation of the total energy and pressure of random substitutional alloys within the Korringa-Kohn-Rostoker coherent-potential approximation. The theory is used to calculate the concentration variation of the equilibrium lattice spacing of $\alpha$-phase ${\mathrm{Cu}}_c{\mathrm{Zn}}_{1-c}$ alloys. We find, in agreement with experiment, that the variation is almost linear and that it deviates from Vegard's rule.

We observe discrete plasmons in layered 2D electron gases with a large, but finte, number of periods. The twofold degeneracy of plasmon modes with wave numbers in the first Brillouin zone of the infinite system is lifted by the loss of complete periodicity in the finite system. These characteristic discrete plasmon doublets are measured in inelastic-light-scattering spectra of multilayer GaAs/(AlGa)As heterostructures.

Using a first-principles disordered-local-moment picture of itinerant-electron magnetism, we calculated the temperature and volume dependence of the magnetic moment and spin-spin correlations for fcc Fe in the paramagnetic state.

Grain boundaries are known to reduce significantly the electrical dc conductivity of polycrystalline metallic materials. In this paper, we give a quantum mechanical calculation of the grain-boundary resistance based on the transfer-matrix approach. The results show an exponential decrease of the conductivity with respect to the number of grain boundaries per mean free path in accord with an empirical model proposed recently.

The interaction of surface acoustic waves with a two-dimensional electron system is investigated on $\frac{\mathrm{GaAs}}{{\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}}$ heterojunctions at low temperatures ($T<~4.2 \mathrm{K}$) and high magnetic fields (≤ 10 T). Surface acoustic waves are propagated through the heterojunction containing a high-mobility two-dimensional electron gas and situated between the emitting and receiving transducers. The interaction between the two-dimensional electron system and the surface acoustic wave produces strong quantum oscillations in the sound attenuation and the sound velocity which can be quantitatively explained.

A sufficient condition for the quantum entropy, $-\mathrm{Tr}\left(\rho \ln \rho \right)$, to be nondecreasing under a tracepreserving positive linear map is that the "totally random" state, $\rho \propto 1$, be stationary. It is argued that this condition will be satisfied by the quantum system consisting of the region external to one or more black holes. This would explain why a "generalized second law of thermodynamics" appears to hold in the presence of black holes.

Contrary to the claim made by Das, it is shown that there is an arbitrariness in the solutions of the chiral Schwinger model. The results, which have been obtained by employing the point-splitting method, can be put in one-to-one correspondence with those of Jackiw and Rajaraman.

We have observed a signal for the decay $D^0\to \phi {\overline{K}}^0$. We find that a broad threshold enhancement in the $K^{+}{K}^{-}$ mass spectrum in the decay $D^0\to K^{+}{K}^{-}{\overline{K}}^0$ is the main source of background to the $D^0\to \phi {\overline{K}}^0$ signal. Accounting for this background, we obtain the branching fraction $B(D^0\to \phi {\overline{K}}^0)=(1.18\mathrm{}\pm 0.40\pm 0.17)\%$.