Abstract-Space-charge neutralization is required to compress and focus a pulsed, high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We described approaches to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons. Among the options are plasma injection from pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means, by an array of movable Langmuir probes, by a small single probe, and by evaluating Stark broadening of the Balmer H spectral line. In the main approach described here, the plasma is produced at several cathode spots distributed azimuthally on the ring cathode. It is shown that the plasma is essentially hollow, as determined by the structure of the magnetic field, though the plasma density exceeds 10 14 cm -3 in practically all zones of the solenoid volume if the ring electrode is placed a few centimeters off the center of the solenoid. The plasma is non-uniform and fluctuating, however, since its density exceeds the ion beam density it is believed that this approach could provide a practical solution to the space charge neutralization challenge.2
Due to low cost of operation, high deposition rates and efficiency, wire arc spraying has become one of the most important thermal spray technologies, especially as a tool for coatings used to improve corrosion and wear protection. In order to obtain high-quality coatings, the flow characteristics of the atomizing gas have to be optimized. Thus, the nozzle design as well as the properties of the gas used need to be adjusted and the resulting particle parameters have to be quantified. Employing the Accurasprayg3 system in combination with Laser Doppler Anemometry (LDA), the particle size distribution and velocity have been measured for a wide range of parameters, including different materials, different gas pressures and nozzles resulting in design suggestions and offering the possibility to compare the two different diagnostic systems.
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