Here are presented experiments on fine particles levitating in low-pressure weakly ionized plasmas under a vertical magnetic field. The magnetic field is useful to provide a vertically long cylindrical column of fine-particle clouds, yielding even string-shaped vertically aligned fine particles, under the double-plasma configuration. Measurements show that fine-particle clouds rotate in the azimuthal direction on the horizontal plane even in such a weak magnetic field that positive ions are slightly magnetized. With an increase of the magnetic field, the rotation speed increases, being followed by subsequent saturation. The rotation speed and direction can be controlled by varying radial plasma potential and/or density profiles. The rotation is induced under the condition that the interparticle distance is small enough for the strong Coulomb coupling among fine particles. A mechanism of the rotation could be explained by effects of ion motions on fine particles, which are modified in the presence of the vertical magnetic field.

No abstract

Electron-temperature control is performed on plasmas passing through a coarse mesh grid from a discharge region. By increasing a negative potential applied to the grid, the electron temperature is continuously decreased in a very wide range covering almost two orders of magnitude down to the value nearly equal to the background gas temperature in case of direct current argon or helium gas discharge. The temperature decrease is accompanied by an increase in the electron density. This method of electron-temperature control can also be applied to plasmas produced by radio-frequency and electron cyclotron resonance discharges.

Measur:ments of the dc susceptibility g( T), dc magnetization, magnetoresistivity, and magnetostriction are tjtilized to delineate the magnetic B-T phase diagram of the antiferromagnetically ordered ( Tz = 14 ki) heavy-fermion superconductor ( T, =2 K) UPd, A13. The single-crystal data reveal three antiferroma(;netic phases for Blc, but only one for Bric. The anisotropic y(T) in the paramagnetic state suggests a tetravalent configuration of uranium.One of the essential open questions in heavy-fermion physics concerns the interference of antiferromagnetism and superconductivity of strongly renormalized carriers, ' this question being related to the potential role of magnetic fluctuations in the Cooper pairing in heavy-fermion superconductors (HFS's). Coexistence between HFS's and antiferromagneti!m with extremely small ordered moments,

Collisions between C 2 60 and alkali-metal ion are investigated by an ab initio molecular dynamics simulation at 1000 K. When Li 1 with kinetic energy ϳ5 eV hits the center of a six-membered ring of C 2 60 , Li@C 60 is created. If either the kinetic energy is lower or the collision occurs off center, the Li 1 ion stays outside, and C 60 is deformed by the shock. In some cases, several bonds of C 60 break after the bombardment; this may make the insertion of alkali-metal ion easier. [S0031-9007(96)00138-X] PACS numbers: 61.46. + w