Scaling of DD fusion power in a nanosecond vacuum discharge

Earlier, in a nanosecond vacuum discharge (NVD) with a deuterated Pd anode, the appearance of DD neutrons was observed not only at the well-studied quasi-stationary stage, where a virtual cathode (VC) appears in the interelectrode space, but also at the very initial stage of the discharge. An analysis of the experiment shows that the autoelectron beam can play the role of a kind of trigger for starting DD syntheses processes on the surface or in the bulk of the Pd anode, but its mechanism at the initial stage of the discharge remained unclear. In this work, we performed PiC modeling of the possible partial penetration of a beam of autoelectrons into hollow anode Pd tubes. This leads to the formation of very small short-lived VCs inside individual Pd tubes, where, starting from a current of 100 A, DD microsynthesis is possible. It is shown that in devices with oscillating ions the favorable scaling of the DD fusion power, which increases with decreasing VC radius, can be retained up to rVC  0.02 cm.

Investigation of Compact Hollow-Anode Discharge Source for Copper Thin Films by Sputtering Processes

A compact hollow-anode discharge (HAD) source with a size of 60 mm in radius and 70 mm in length has been developed to stably generate plasma jets for various sputtering processes in semiconductor and display fabrications. A developed HAD plasma source has been investigated by cylindrical electric probes, and the experimental results were compared to the values of numerical calculations. A uniform density discharge model with a geometry factor was proposed to estimate the profiles of plasma parameters. Owing to the difference of absolute magnitude, even with the similar trend of spatial variation, plasma parameters such as electron temperature (Te) and plasma density (ne) measured at z = 3 cm have been calibrated by the values of numerical calculations at the nozzle entrance (z = 0 cm, at the throat of the jet), and the calibration factors for Te and n0 have been deduced by comparing the experimental values to numerical calculations. These are to be explained by the decay mechanism along the axis of the jet with elastic collisions in terms of the mean free path. The developed HAD plasma source was tested for the deposition of Cu thin films with an optimized condition as a plausible application to sputtering processes.

Plasma welding of high-strength aluminum alloys

On the analysis basis of trends in the development of aluminum alloy plasma welding it is shown that in most cases for critical structures there is used welding with a non-consumable electrode on reversed polarity with adding wire material. A welding method with a hollow anode to increase non-consumable tungsten electrode durability is described. It is shown that to increase quality of welded joints in aluminum-lithium alloys the application of plasma-forming gas programmable pulse feed has promising outlooks. In this case side by side with the decrease of such defects as pores and oxide films the obtaining of more fine-grained structure in metal seams is marked.