It is calculated that an unpolarized electron beam elastically scattered from a chiral molecule will acquire a net helicity of $H\left(s\right)\mathrm{}\sim \eta {\left(\alpha Z\right)}^2$, where $\alpha =\frac{e^2}{\hslash c}$, $Z$ is the atomic number of the heaviest atom in an asymmetric environment in the molecule, and $\eta$ is a molecular asymmetry factor. For a carbon center ($Z=6\mathrm{}$), $\eta$ is estimated to be ${10}^{-2\mathrm{}}$ so that $H\left(s\right)\mathrm{}\sim {10}^{-5\mathrm{}}$, which would account for its lack of observation in a recent experiment sensitive to $H\left(s\right)>5\mathrm{}\times {10}^{-3\mathrm{}}$. The calculation of other asymmetric electron (and positron)-chiral molecule interactions is discussed.

Microwave spectroscopy has been employed to make the first definite experimental observation of the ionic metastable isomer HO${\mathrm{C}}^{+}$. Its $J=0\mathrm{}\to 1$ transition and those of its ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ isotopic variants have been detected in laboratory dc glow discharges. Extensive chemical, spectroscopic, and theoretical evidence permits conclusive identification of these spectra. Comparison of the substitution bond lengths [${\mathcal{r}}_s\left(\mathrm{CO}\right)=1.1595\mathrm{}$ Å and ${\mathcal{r}}_s\left(\mathrm{OH}\right)=0.9342\mathrm{}$ Å] to ab initio structures strongly supports a large-amplitude (low-frequency) bending vibration.

Formation of density cavities, spiky turbulence, and electromagnetic radiation at the plasma frequency (${\omega }_p$) and its harmonics are observed simultaneously in the presence of a cold-electron beam. The electrostatic and electromagnetic frequency spectra evolve with the development of cavities.

The enhancement of the ponderomotive potential near gyroresonance is investigated both experimentally and theoretically. Because of nonadiabaticity near gyroresonance the potential is finite and depends on the transit time of the particle through the rf field structure.

The criterion for the existence of vortexlike ion phase-space configurations, as obtained by a standard pseudopotential method, is found to coincide with the criterion for the linear instability for two (cold) counterstreaming ion beams. A nonlinear equation is derived, which demonstrates that this instability actually evolves into such phase-space configurations. A small, but nonzero, ion temperature turns out to be essential for the saturation into stationary structures.

The CLEO device has been used to compare the confinement properties of a variety of Ohmically heated toroidal configurations at the same magnetic field. These include RFP and OHTE configurations, conventional tokamaks, a novel helically assisted low-$q$ tokamak, and an $l=3\mathrm{}$ stellarator. The plasma current and density vary over 2 orders of magnitude for the different configurations. The stellarator exhibits the best energy confinement time, ${\tau }_E$, but the tokamak achieves the best $\beta {\tau }_E$ product.

A theory of drift-wave turbulence as a low-density gas of drift-wave solitons is developed. In the ideal-gas approximation to the many-soliton system the dynamical form factor $S(k, \omega )$ is computed and shown to peak at $\omega >k{v}_d$ with a substantial width $\Delta \omega$ for a given azimuthal wave number.

A formalism is presented for calculating all the normal growth modes of the Rayleigh-Taylor instability in a stratified fluid of arbitrary profile. The classical instability is suppressed by the introduction of a finite density gradient at the interface, a technique applicable to inertial-confinement fusion targets.

The requirement that supersymmetry be unbroken in a supersymmetrized gauge theory is shown to imply vanishing Dynkin weight of the components of the Higgs field representation receiving vacuum expectation values. As a corollary a compact expression is obtained for the Dynkin weights of general $\mathrm{SU}\mathrm{}\left(N\right)\mathrm{}$ representations. Examples are given for supersymmetrized grand unified theories.

Doubly excited autoionizing states in barium of the configuration $6p_{\frac{3}{2}}\mathrm{np}$ ($n>~12$) are shown to decay preferentially to yield the $6p_{\frac{1}{2}}$ excited state of ${\mathrm{Ba}}^{+}$. The resulting population inversion is used to produce amplified spontaneous emission at 493 and 650 nm corresponding to the $6p_{\frac{1}{2}}-6\mathrm{}{s}_{\frac{1}{2}}$ and $6p_{\frac{1}{2}}-5\mathrm{}{d}_{\frac{3}{2}}$ transitions in ${\mathrm{Ba}}^{+}$. This principle of selective autoionization is expected to be applicable to the construction of a new class of ion lasers extending into the vacuum-ultraviolet wavelength region.

A large discrepancy between Dirac-Fock calculations and experiment for the spin-orbit splitting, ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}-{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$, in the ground states of B- and F-like ions is resolved. The discrepancy arises from spurious terms which are inherent in the relativistic self-consistent-field procedure. Removal of these terms substantially improves the agreement between theory and experiment on spin-orbit splitting.

A computer simulation of a one-dimensional electron-ion plasma is described. The results differ substantially from the predictions of the conventional theory of this system. In particular, an instability is observed whose onset occurs for electron drifts well below the threshold of the linear ion acoustic instability and which ultimately dominates the nonlinear evolution of the linear instability.

Some experimental observations of rotamak equilibria made in a high-power, short-duration (∼80-μs) experiment and a complementary low-power, long-duration experiment are summarized. In the high-power experiment two possible equilibrium phases have been identified: an oblate, compact torus configuration and a $\beta =1\mathrm{}$, mirrorlike configuration. In the low-power experiment toroidal plasma current has been driven, and a compact torus configuration has been maintained, for several milliseconds.

A technique is presented for the measurement of magnetic helicity from values of the two-point magnetic-field correlation matrix under the assumption of spatial homogeneity. Knowledge of a single scalar function of space, derivable from the correlation matrix, suffices to determine the magnetic helicity. The technique is illustrated by a report of the first measurement of the magnetic helicity of the solar wind.

A direct method for measuring the desorption time constant of flash-desorbed ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ films (≲ 1 monolayer), adsorbed on Nichrome or Constantan heaters, is described. A time constant $\tau$ is found which behaves as $\tau ={\tau }_0\exp \left[\frac{E}{T_s}\right]$, where $T_s$ is the heater temperature. The value for the characteristic lifetime ${\tau }_0$ is ${10}^{-9\mathrm{}}$-${10}^{-10\mathrm{}}$ sec, orders of magnitude shorter than that previously reported. The measured energy parameter $E$ was found to be $\sim \frac{2}{3}$ of the chemical potential.

Dielectric, ultrasonic, and neutron-scattering measurements in ${\left(\mathrm{KBr}\right)}_{1-x}{\left(\mathrm{KCN}\right)}_x$ are reported for concentrations $x$ ranging from 0.01 to 0.5. The dipolar and the quadrupolar susceptibilities exhibit frequency- and concentration-dependent cusps showing that the freezing process into an orientational glass state is a relaxational phenomenon.

Dielectric susceptibility measurements for the mixed crystal ${\mathrm{}\left(\mathrm{KBr}\right)\mathrm{}}_{0.50}$ ${\mathrm{}\left(\mathrm{KCN}\right)\mathrm{}}_{0.50}$ are reported in the frequency range $20 \mathrm{Hz}<f<\mathrm{}80\mathrm{} \mathrm{kHz}$. An anomaly is found at temperatures far below that where neutron and Brillouin studies find mode softening. The results are interpreted in terms of a possible dipole-glass phase that has been recently proposed for this system.

Electrical detection of a single donor level of interstitial boron at $E_c-0.13\mathrm{}$ eV using novel photo—deep-level transient spectroscopy techniques is reported. Complementary behavior between this level and the acceptor level at $E_c-0.45\mathrm{}$ eV establishes that the defect levels have negative-$U$ ordering. The donor level exhibits a large Poole-Frenkel effect which, when properly accounted for, provides a direct and unambiguous connection to the EPR-identified interstitial boron atom. This represents the first definitive indentification of negative-$U$ properties for a defect in any solid.

It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

Relaxation of optically excited carriers within localized continuum states in heavily doped crystalline GaAs is directly observed by picosecond luminescence experiments. The relaxation within localized states takes place via thermally activated multiple trapping. Saturation of the relaxation is observed at high temperatures and for small trap densities. The results demonstrate that heavily doped crystalline semiconductors can serve as a simple model for amorphous materials.