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Absorption spectroscopy and emission spectroscopy were used to examine the afterglow from radio frequency inductive excited discharges in Xe and I2 mixtures. The findings show that exciplex XeI* results in the afterglow when ground state Xe and highly excited I2 are combined. Ion-ion neutralization was also found to be an important precursor reaction for the development of I*(2P3/2) as well as of Xe*, Xe**, I2*, I2** and other excited species found in the afterglow.

An experiment was conducted to study the kinetics of low pressure, 0.5-5 Torr, radio-frequency inductively excited discharges sustained in Xe and I2 to determine the source of radiating states. The diagnostics used in the study include optical absorption and emission spectroscopy, microwave absorption and microwave interferometry. Results showed that in time modulated discharges, the emissions from excited states of atomic iodine decays with time constants of hundreds of microseconds.

The low pressure radio frequency inductive discharges sustained in Xe/I2 mixtures for the production of ultraviolet radiation from XeI(B->X) at 253 nm was studied. Laser-induced fluorescence, optical absorption spectroscopy and optical emission spectroscopy were applied. Findings showed that for the experimental conditions, Xe+I2 -> XeI(B)+I is a major reaction which produces the excimer.

An examination of the development of diamond films and their physical properties reveals that changes in surface chemistry parameters and gas phase chemistry parameters during settlement of microwave chemical vapor regulate the surface morphology of diamond films. Enhanced initial surface roughness increases the wear factor and does not influence the equilibrium coefficients and friction. In dry nitrogen and humid air, the equilibrium coefficients of friction are 0.02-0.04, and in vacuum they are 1.5-1.8.

The thickness dependence of critical current density (Jc) has been investigated in YBa2Cu3O7-x films with BaZrO3 (BZO) nanorods (YBCO/BZO) aligned along the film normal. With the presence of linear defects in the YBCO/BZO films, the thickness dependence of Jc becomes negligible at self field and weak applied magnetic field (H), suggesting these linear defects playing a key role to the elimination of the thickness dependence of Jc. The effect of temperature (T) and H on Jc thickness dependence have been investigated and comparisons have been made between YBCO and YBCO/BZO samples. Since BZO nanorods alignment is greatly influenced by growth temperature, the quantitative difference in terms of nanorod's density and average length is reflected on Jc angular dependence of H and Jc thickness dependence as thermally assisted flux motion (TAFM) becomes important above a threshold H determined by the BZO nanorod density. With further increasing H, a monotonically increasing Jc vs. thickness trend was observed in YBCO/BZO films, in contrast to an opposite trend when collective pinning is dominant. This result suggests the thickness dependence of Jc is dictated by the microstructure and hence pinning mechanism in YBCO films. [ABSTRACT FROM AUTHOR]

We report on the effects of different multifilamentary geometries on the dynamic current and field distributions in YBa2Cu3O7-δ thin films. Finite-element model simulations are presented that allow a direct comparison of the calculated magnetic flux and current profiles with experimental data obtained by time-resolved magneto-optical imaging. We find that increasing the distance between filaments reduces the magnetic coupling and decreases the ac losses. Screening and transport currents also redistribute more evenly between all filaments. The measured transport current density profiles are in good agreement with the modified critical state model. [ABSTRACT FROM AUTHOR]

Multifilamentary coated conductor (MFCC) samples with patterned links have been studied using transport and scanning laser microscopy (SLM) techniques. Striation patterns are fashioned to define multiple filaments with discretely placed superconducting (SC) links between the filaments for current sharing and redistribution. After initial measurements, an artificial incision is made on a filament to mimic a disabled filament. The changes in global and local current transport characteristics are noted for in terms of the redistribution of current flow and the modification of local dissipation. Our results show that the patterned links between filaments play a vital role in redistributing current and encouraging current sharing. We find that the main factors in limiting the current-carrying capability of MFCC samples are local current density increases, which we call “current crowding.” The susceptible areas for current crowding are several: (1) filaments adjacent to the disabled ones, since the intact filaments have to carry extra current, (2) the links where current redistribution occurs, and (3) the partially blocked filament. [ABSTRACT FROM AUTHOR]

A simple investigation into the properties of weakly linked filaments in striated YBa2Cu3O7-d (YBCO) coated conductors has been performed. Such weak-link connections may arise in two different contexts within the coated conductors, the one case being the occurrence of unintentional connections. However, it may be desirable to intentionally induce the weak-link connections in order to allow a current sharing between the filaments. This allows the localized degradation of a given filament to be circumvented at a small cost in terms of the added losses and magnetization. This problem has been treated mathematically with a comparison of the superconductor weak linking in contrast to the normal-metal-induced current sharing. The estimates for target values of filament coupling are deduced, and the results in terms of magnetization are then determined. The YBCO samples created, using the pulsed laser deposition, are described that have these properties. The samples consist of one control and one striated sample. The magnetization response of these samples is then considered in terms of the expressions developed. [ABSTRACT FROM AUTHOR]

The thickness dependence of critical current density ([J.sub.c]) is examined in Y[Ba.sub.2][Cu.sub.3][O.sub.7-x] films with BaZr[O.sub.3] (BZO) nanorods (YBCO/BZO) aligned along the film normal. The results have shown that the thickness dependence of [J.sub.c] is dictated by the microstructure and hence pinning mechanism in YBCO films.

The effects of different multifilamentary geometries on the dynamic current and field distributions in Y[Ba.sub.2][Cu.sub.3][O.sub.7-[delta]] thin films are studied. The studies have shown that increasing the distance between filaments has reduced the magnetic coupling and has decreased the ac losses.

Transport and scanning laser microscopy (SLM) techniques are used for studying multifilamentary coated conductor (MFCC) samples with patterned links. The results have shown that the patterned links between filaments have played important role in redistributing current and encouraging current sharing.

The properties of weakly linked filaments in striated YBa2CuO(sub 7-d) (YBCO) coated conductors are investigated. The results indicate the potential of using weakly linked striations to allow current sharing between high temperature superconductor (HTS) filaments of striated coated conductors while still reducing the associated hysteretic loss.

Presents a study that investigated friction and wear of plasma-deposited diamond films. Experimental procedures for the preparation of the diamond films; Conditions of friction and wear experiment; Characterization of diamond films.