Bo-Hyun Chung

Low carbon process development for iron production

An arc plasma torch system for iron production with low carbon exhaust has been developed. Instead of using cokes, H2 and CH4 gas are used as plasma forming gases for direct reduction of iron oxide. Three carbon rods are used as electrodes, and each electrode is connected with one phase of three phase A.C. power supply. Arc discharge is sustained between the two of three electrodes, and electrodes manipulating device is designed to feed the electrodes into furnace to maintain fixed electrode gap during operation. Plasma gas is injected from the bottom of furnace, and the exhausted gas flow is upward. Temperature and enthalpy distribution of arc plasma are obtained for various operating conditions such as applied voltage, arc current, plasma gas flow rate etc., by numerical method. Chemical equilibria of materials are calculated using conventional code for these data. The relation among iron production rate, operating conditions (input power, gas flow rage) and carbon dioxide exhaust rate are discussed.

RaD Status of the 700 MHz, 1MW Klystron for PEFP

KAPRA (Korea Accelerator and Plasma Research Association) are undertaking the first phase R&D for the 1 MW, CW 700 MHz klystron, which is targeting the future stage of the PEFP (Proton Engineering Frontier Project) accelerator at KAERI (Korea Atomic Energy Research Institute). The objectives of the first phase R&D are 1) setting up infra structures/procedures for the design and fabrication, 2) developing a prototype klystron for proofs of principles, and 3) making a performance test of the prototype at a reduced duty. The second phase R&D is supposed to cover full power, CW operation and reliability issues. In this paper, a summary of the R&D status during the first phase for PEFP 1 MW, 700 MHz klystron is reported.

Study of inductively coupled plasma effects for ZO:N thin films

ZnO has been considered in various industrial applications owing to its piezoelectric properties and wide band gap of near ultraviolet. However, its application to optoelectronic and display devices is still very limited due to the difficulty in obtaining good and stable p-type ZnO. In order to study p-type ZnO (ZO:N), we developed a plasma enhanced atomic layer deposition (PEALD) system adopting an inductively coupled plasma (ICP) source; its plasma generation was carried out and ZnO thin films were fabricated using both PEALD and ALD process. Diethylzinc was used as a zinc precursor, H2O as an oxidant, nitrogen as a dopant, and argon as a carrier and purge gas. Self-limiting growth and doping effects were investigated at various flow rates, reaction times and radio-frequency powers. The properties of thin films were investigated using field emission scanning electron microscopy (FESEM), Auger electron spectroscopy (AES), Hall measurement, photoluminescence measurement (PL), X-ray diffraction (XRD), etc. Detailed results will be presented.

The R&D status of 700MHZ 1MW CW klystron

KAPRA (Korea Accelerator and Plasma Research Association) is conducting a project of designing and making a 1 MW, 700 MHz klystron which purpose the future stage of the PEFP (Proton Engineering Frontier Project) proton accelerator at KAERI (Korea Atomic Energy Research Institute). And KAPRA has completed the proto-type klystron for proofs of principle and the performance test in first phase. The second phase is in progress at present. The goals of this phase are 1) making the new advanced klystron which was base on adjustment and repletion of previous work 2) setting up infra structure for baking, assembling, and supporting fabrication process 3) covering full power, operating CW and reliability issue 4) training the young scientists and engineers. In this paper, a summary of R&D status and results.

Test of 700MHz, 1MW proto-type klystron for PEFP

High power and RF source of 700 MHz and 1 MW klystron, which has been designed and constructed by the Korean Accelerator and Plasma Research Association, has been tested. To test the primary performance of the klystron, a pulse power supply was used to manipulate a negative high voltage. We are currently reinforcing the protection circuit, and it is going on without much trouble as originally planned. In addition, a baking furnace for the klystron is under fabrication for the ultra high vacuum with better stability. We have constructed various infrastructures such as the baking furnace for the development of the klystron.