Optical coatings are used in lasers systems for fusion research to control beam propagation and reduce surface reflection losses. The performance of coatings is important in the design, reliability, energy output, and cost of the laser systems. Significant developments in coating technology are required for future lasers for fusion research and eventual power reactors.

Two primary irradiation-induced changes occur during neutron irradiation: the displacement of atoms forming crystal defects and the transmutation of atoms into either gaseous or solid products. The material scientist studying irradiation damage to material by fusion-produced neutrons is faced with several questions: Is the nature of high-energy (14-MeV) displacement damage the same as or different from that caused by fission neutrons (< 2 MeV). How do the high helium concentrations expected in a fusion environment affect the material properties. What effects do solid transmutation products have on the behavior of the irradiated materials. In the past few years, much work has been done to answer these questions. This paper reviews recent work in this area.

The radiation dose rates to man from uranium milling activities are discussed. The sources of radiation, the radioisotopes involved, and the environmental exposure pathways are described. Risks of cancer to exposed individuals are presented and recommendations made for mitigation of contamination. (ACR)

The use of empirical pseudopotentials, in evaluating interatomic potentials, provides an inexpensive and convenient method for obtaining highly accurate potential curves and permits the modeling of core-valence correlation, and the inclusion of relativistic effects when these are significant. Recent calculations of the X/sup 1/..sigma../sup +/ and a/sup 3/..sigma../sup +/ states of LiH, NaH, KH, RbH, and CsH and the X/sup 2/..sigma../sup +/ states of their anions are discussed. Pseudopotentials, including core polarization terms, have been used to replace the core electrons, and this has been coupled with the development of compact, higly-optimized basis sets for the corresponding one- and two-electron atoms. Comparisons of the neutral potential curves with experiment and other ab initio calculations show good agreement (within 1000 cm/sup -1/ over most of the potential curves) with the difference curves being considerably more accurate. In the method of computer molecular dynamics, the force acting on each particle is the resultant of all interactions with other atoms in the neighborhood and is obtained as the derivative of an effective many-body potential. Exploiting the pseudopotential approach, in obtaining the appropriate potentials may be very fruitful in the future. In the molecular dynamics example considered here, the conventional sum-of-pairwise-interatomic-potentials (SPP) approximation is …

While precision machining has been applied to the manufacture of optical components for a considerable period, the process has, in general, had its thinking restricted to producing only the accurate shapes required. The purpose of this paper is to show how optical components must be considered from an optical (functional) point of view and that the manufacturing process must be selected on that basis. To fill out this perspective, simplistic examples of how optical components are specified with respect to form and finish are given, a comparison between optical polishing and precision machining is made, and some thoughts on which technique should be selected for a specific application are presented. A short discussion of future trends related to accuracy, materials, and tools is included.

This report gives the preliminary results on work done to find a scintillator that is compatible with high-bandwidth, long-distance fiber-optic transmission. The requirements for such a scintillator are: (1) emission in the near-IR; (2) linear output over 2 to 3 decades of input excitation; (3) time response < 2 ns; and (4) immunity to radiation damage. The behavior of single crystal cadmium sulfide (CdS) and cadmium selenide (CdSe) was examined under electron and laser excitation. Both crystals emit in the deep red, however, time response was found to be slower than 2 ns. Neither crystal exhibited good linearity over the entire range of input excitation.

Damage tests of Ta/sub 2/O/sub 5//SiO/sub 2/ antireflection films deposited under a variety of conditions showed that thresholds of films deposited at 175/sup 0/C were greater than thresholds of films deposited at either 250/sup 0/C or 325/sup 0/C. Deposition at high rate and low oxygen pressure produced highly absorptive films with low thresholds. Thresholds did not correlate with film reflectivity or net stress in the films, and correlated with film absorption only when the film absorption was greater than 10/sup 4/ ppM. Baking the films for four hours at 400/sup 0/C reduced film absorption, altered net film stress, and produced an increase in the average damage threshold.

Molecular dynamics calculations are presented that address the extent of microscopic detail that can be deduced from macroscopic gauge measurements of shock propagation in condensed systems. Large asymmetrically shock-loaded lattices were simulated, varying the initial temperature and the strength of shock loading. Randomly-placed mass defects were introduced into the lattice, and the degradation of the shock front with the subsequent development of fracture and chunky spall were studied and compared with the coherent microscopic spall found for perfect lattices.