Byoung Seob Lee

Superconducting magnet performance for 28 GHz electron cyclotron resonance ion source developed at the Korea Basic Science Institute

A superconducting magnet for use in an electron cyclotron resonance ion source was developed at the Korea Basic Science Institute. The superconducting magnet is comprised of three solenoids and a hexapole magnet. According to the design value, the solenoid magnets can generate a mirror field, resulting in axial magnetic fields of 3.6 T at the injection area and 2.2 T at the extraction region. A radial field strength of 2.1 T can also be achieved by hexapole magnet on the plasma chamber wall. NbTi superconducting wire was used in the winding process following appropriate techniques for magnet structure. The final assembly of the each magnet involved it being vertically inserted into the cryostat to cool down the temperature using liquid helium. The performance of each solenoid and hexapole magnet was separately verified experimentally. The construction of the superconducting coil, the entire magnet assembly for performance testing and experimental results are reported herein.

Depth profile analysis of nanometric multilayer coatings by radio-frequency glow discharge optical emission spectroscopy

Radiofrequency glow discharge optical emission spectrometry(RF-GD-OES) was used to quantitatively analyze the depth of nanometric Cr/Ni multilayers on a silicon substrate. The technique permitted rapid and accurate depth profiling of multilayers, down to the nanometer range. The analytical parameters were optimized for the RF-GDOES depth quantitative analysis of Cr/Ni multilayers on a Si substrate. To validate the RF-GD-OES results, a TEM image was obtained in addition to performing the AES and SIMS depth profiling. The findings indicate that RF-GDOES is a promising analytical tool for the accurate and rapid depth profiling of nanometric metal multilayers on semiconducting substrates.

An In-situ XPS study of non-evaporable ZrVFe getter material

To investigate the temperature dependence of a synthesized Zr57V36Fe7 non evaporable vacuum getter material, the in-situ temperature x-ray photoelectron spectroscopy (in-situ XPS) were performed in a UHV chamber equipped with a programmable ceramic sample heating system. The surface and bulk composition of Zr, V, and Ti was determined in the as-received state and after in-situ heating from 100 °C to 600 °C at 100 °C per step. The peak fitting results for O 1s, C 1s, Zr 3d, V 2p, and Fe 2p high resolution spectra were acquired and the chemical state of the elements were then characterized as a function of heating temperature. In-situ XPS investigations showed that oxide reduction proceeds via the formation of sub-oxides with the simultaneous formation of carbides in the region near the surface. The activation temperature for completion of the Zr57V36Fe7 alloy, which approximates the XPS peaks changed from oxide to metallic state (20 % of the oxide peak), was determined around 480 °C The findings suggest that the in-situ temperature XPS technique is a useful analytical tool for evaluating activation characteristics of NEG materials.