Coatings for laser fusion targets were deposited up to 135 μm thick by plasma polymerization onto 140 μm diam DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 μm) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power, gas flow, and pressure, and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets.

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Mineralization of implanted bioprostheses poses a major clinical problem. Crosslinking of collagenous matrices, a process used to render tissues relatively inert and nonbiodegradable, seems to encourage calcification. Residual, noncovalently bound glutaraldehyde, as well as glutaraldehyde crosslinks which can be degraded with time, seem to play a role in this connection.Our findings demonstrate the need to carefully remove noncovalently or labile-associated glutaraldehyde by thorough rinsing or neutralization before implantation. Components of a valve prosthesis such as cusps and aortic wall, which are known to vary in their proportions of collagen, elastin, and noncollagenous proteins and to calcify to different extents, can both be prevented from calcifying if treated with a biphosphonate before implantation. Calcification can also be reduced by selective enzymatic removal of noncollagenous materials. In addition to the age of rats, animals usually used to evaluate calcification, the strain of animal can markedly affect the response. The Fischer-344 rat, a highly inbred animal, will not calcify exhaustively rinsed implants. Our findings suggest that multifactorial approaches may have to be combined to generate the most ideal bioprostheses. These should include careful removal of noncovalently bound glutaraldehyde, neutralization of the nonbifunctionally reacted residues, removal of lipids and noncollagenous proteins (and possibly the more antigenic nonhelical collagen telopeptides), as well as inclusion of agents such as biphosphonates, which by interfering with crystal growth prevent the accumulation of mineral in the interstices of the tissue.

Efficient conversion of laser light into EUV radiation is one of the most important problems of the laser-produced plasma (LPP) EUV source. Too low a conversion efficiency (CE) increases the amount of power the drive laser will have to deliver, which, besides the obvious laser cost increase, also increases the thermal load on all the components and can lead to increased debris generation. In order to meet the requirements for a high-volume manufacturing (HVM) tool and at the same time keep the laser power requirements within acceptable limits, a CE exceeding 2.5% is likely to be required. We present our results on optimizing conversion efficiency of LPP EUV generation. The optimization parameters include laser wavelength, target material, and laser pulse shape, energy and intensity. The final choice between parameter sets that leads to the required minimum CE is dependent on the debris mitigation solutions and the laser source available for a particular parameter set.