Experimental study of single vs. two-close-frequency heating impact on confinement and losses dynamics in ECR Ion Sources plasmas by means of X-ray spectroscopy and imaging

We hereby report the study of confinement and electron losses dynamics in the magnetic trap of an Electron Cyclotron Resonance Ion Source (ECRIS) using a special multi-diagnostic setup that has allowed the simultaneous collection of plasma radio-self-emission and X-ray images in the range 500 eV - 20 keV. Argon plasmas were generated in single and two close frequency heating (TCFH) modes. Evidences of turbulent regimes have been found: for stable and unstable configurations quantitative characterizations of the plasma radio self-emission have been carried out, then compared with local measurement of plasma energy content evaluated by X-ray imaging. This imaging method is the only one able to clearly separate X-ray radiation coming from the plasma from the one coming from the plasma chamber walls. X-ray imaging has been also supported and benchmarked by volumetric spectroscopy performed via SDD and HPGe detectors. The obtained results in terms of X-ray intensity signal coming from the plasma core and from the plasma chamber walls have permitted to estimate the average ratio: plasma vs. walls (i.e., plasma losses) as a function of input RF power and pumping wave frequency, showing an evident increase (above the experimental errors) of the intensity in the 2-20 keV energy range due to the plasma losses in case of unstable plasma. This ratio was well correlated with the strength of the instabilities, in single frequency heating (SFH) operation mode; in TCFH mode, under specific power balance conditions and frequency combinations, it was possible to damp the instabilities, thus the plasma losses were observed to decrease and a general reconfiguration of the spatial plasma structure occurred (the X-ray emission was more concentrated in the center of the plasma chamber). In the end, a simplified model has been used to simulate electron heating under different pumping frequencies, discussing the impact of velocity anisotropy vs. the onset of the instability, and the mechanism of particles diffusion in the velocity space in stable and unstable regimes.

IMPROVEMENT OF SELF-ALIGNED DOUBLE PATTERNING USING SPIN-ON-CARBON MATERIAL

In this paper the advantages of using self-aligned double patterning in conjunction with extreme ultraviolet photolithography were analyzed, and a promising spin-on-carbon material used as the layer for the original pattern of the structure to be formed was identified. In addition, a method to treat and protect the shape of the initial profile of regular structure lines by using a direct current superposition on a capacitively-coupled plasma chamber was presented.

The Preliminary Analysis of the Effect of Low-Energy Plasma Treatment on Internal Stresses in a Welded Plate of Steel S355

The articles presents a pilot study aimed to provide preliminary assessment concerning the effect of the low-energy plasma treatment on the level of internal stresses in welded plates. In addition, the article discusses the similarity of a stress relief mechanism based on annealing and that based on low-energy plasma treatment. The extensormetric measurements of internal stresses involving steel S355 after welding and after treatment in the plasma chamber revealed the low-energy plasma treatment-induced reduction of internal stresses.