• 한국진공학회지
• /
• 제19권5호
• /
• pp.331-340
• /
• 2010

초고주파 다중 중공 음극 방전을 이용한 플라즈마 화학 기상 증착 장치를 3차원 수치 모델링하였다. 기본적인 방전 특성을 파악하기 위하여 알곤 플라즈마를 40 MHz, 100 V, 133.3 Pa (1 Torr)의 조건에 대해서 계산하였다. 6 mm 직경의 홀을 20 mm 간격으로 배열하였고 전극 간격은 10 mm를 가정하였다. 피크 플라즈마 밀도는 홀의 하부 중앙에서 $5{\times}10^{11}#/cm^3$ 였으며 전자 온도는 접지 상태로 가정한 기판과 챔버 벽면 주위에서 가장 높았다. 준안정 상태에 의한 2단 이온화 속도는 전자 충돌에 의한 직접 이온화보다 10배 가량 높았다. 수소에 대한 계산에서는 이온화 이외의 다양한 에너지 소모 경로가 있어서 방전의 국재화가 잘 이루어지지 않았다.

• 한국인쇄학회지
• /
• 제23권2호
• /
• pp.93-101
• /
• 2005

The measured plasma temperature of Ar hollow cathode discharge for several metal cathodes are about $620\;{\sim}\;780K$ at discharge current of $7\;{\sim}\;10mA$. The optogalvanic signals were measured using hollow cathode discharge tube with argon as buffer gas at change of discharge currents. A change of ionization rate due to electron collision causes an increase or decrease of the electric conductivity. This change in electric conductivity generates the optogalvanic signal. We conclude that optogalvanic signal has close relation with the lowest metastable atoms density at low current.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
• /
• pp.245-250
• /
• 2004

The discharge current oscillation has been measured for various hollow anode widths and its axial positions using a 1㎾-class anode layer hall thruster. As a result, there were thresholds of magnetic flux density for stable discharge. The plasma structure inside the hollow anode was numerically analyzed using the fully kinetic 2D3V Particle-in-Cell (PIC) and Direct Simulation Monte Carlo (DSMC) methods. The results reproduced both stable and unstable operation modes. In the stable operation case, which corresponds to the case with low magnetic flux, the plasma penetrated into the hollow anode deeper than the case with higher magnetic flux density case. This suggests that comparably large substantial anode area should contribute to stable operation.

• 전기의세계
• /
• 제27권6호
• /
• pp.49-53
• /
• 1978

This paper investigates on the electric input characterisitcs of plasma electron beam in H$_{2}$ gas chamber with various pressures, effected by the shape and dimension of hollow screen cathode during electron beam is formed. The result are as follows: (1)Electron beam is formed in the region of positive resistance on the characteristic curve which shows the relation between the voltage and current of electron beam, independent of the shape and dimension of hollow screen cathode. (2)At a given electron beam current, electron beam voltage increases with the decreases of hollow screen cathode length and screen mesh number of it. (3)At a given electron beam current, electron beam voltage increases with the diameters of hollow screen cathode and electron beam hole of it.

• Korean Membrane Journal
• /
• 제7권1호
• /
• pp.19-27
• /
• 2005

PP hollow fiber membrane was hydrophilized by EVOH dip coating followed by low temperature plasma treatment and UV irradiation. EVOH coating attained high water flux without any prewetting but its stability did not guaranteed at high water permeation rate. At high water permeation rate, water flux declined gradually due to swelling and delamination of the EVOH coating layer causing pore blocking effect. However, plasma treatment reduces the swelling, which suppress delamination of the EVOH coating layer from PP support result in relieving the flux decline. Also, UV irradiation helped the crosslinking of the EVOH coating layer to enhance the performance at low water permeation rate. FT-IR and ESCA analyses reveal that EVOH dip coating performed homogeneously through not only membrane surface but also matrix. Thermogram of EVOH film modified plasma treatment and W irradiation show that crosslinking density of EVOH layer increased. Chemical modification by plasma treatment and UV irradiation stabilized the hydrophilic coating layer to increase the critical flux of the submerged membrane.

• 약학회지
• /
• 제43권2호
• /
• pp.150-159
• /
• 1999

Hollow type suppositories inserted polyvinyl alcohol (PVA) hydrogel capsule containing propranolol·HCI (PPH) were prepared using different bases, polyethylene glycol (PEG), Witepsol H-15 (WH-15) and Witepsol W-35 (WW-35) to improve the controlled release of PPH. The release of PPH from the hollow type suppository inserted PVA hydrogel capsule was retarded than that from PEG, WH-15, or WW-35 hollow type suppositories in rat rectal cavity. When the suppositories were administered to rats, the controlled release of PPH was proved by the plasma concentration-time-profiles of PPH. No significant difference (p〈0.05) among the three different hollow type suppositories was observed in terms of AUC and MRT of PPH. WH-15 hollow type suppository inserted 12% of PVA hydrogel capsule caused irritation to rat rectal mucosa. However, the WH-15 hollow type suppository inserted PVA hydrogel capsule caused no severe irritation on rectal mucosa. The application of the hollow type suppositories using PVA in sustained rectal delivery of drugs might be feasible.

• 한국연소학회지
• /
• 제10권4호
• /
• pp.24-32
• /
• 2005

Various types of plasma source applied in $CH_4$ decomposition process are compared. DBD by pulse and AC power, spark by pulse and AC power, rotating arc and hollow cathode plasma are chosen to be compared. The results show that $CH_4$ conversion per given unit power is relatively high in hollow cathode plasma and rotating arc that induces rather high temperature condition and that is why both thermal dehydration and plasma induced decomposition contribute for the overall process. In case of DBD wherein high temperature electron and low temperature gas molecule coexist, the process shows low conversion rate, for in rather low temperature condition the contribution of thermal dehydration is lowered. Selectivity of $C_2H_6$ and $C_2H_2$ is shown to be a good parameter of the relative contribution of plasma chemistry in the overall process. From the results we concluded that required condition of plasma source for a cost effective and high yield $CH_4$ decomposition is to have characteristics of both thermal plasma and non thermal plasma in which temperature is high above a certain threshold state for thermal dehydration and electron induced collision is maximized in the same breath.

• 분석과학
• /
• 제15권6호
• /
• pp.502-508
• /
• 2002

관통형 속빈 음극관 글로우 방전 (See-through hollow cathode glow discharge)셀을 이용한 미량 및 극미량 분석을 가능한 분광 분석 장치를 개발하였다. 이 장치는 기존의 관통형 속빈 음극관 글로우 방전 셀을 개선하기 위하여 수냉식 냉각 장치를 부착한 새로운 방전 셀의 형태로 개발하였다. 기존의 방전 셀로 미량 및 극미량 분석은 가능하였지만, 공랭식 냉각장치로도 플라즈마의 온도를 높이는 데 한계가 있으며, 단 시간에 플라즈마가 불안정해지는 문제점이 발생하였다. 이러한 문제점을 개선하기 위해서 본 장치에서는 수냉식 냉각 방식을 채택하여 플라즈마의 안정성을 높였으며, 플라즈마 온도를 증가시킬 수 있다. 개선된 방전 셀의 기초 연구를 위해 속빈 음극관의 재질 및 구경변화에 따른 방전 전력 및 압력에 관련한 연구를 하였으며, 속빈 음극관의 구경의 변화에 따른 플라즈마 온도 변화에 대해 측정하였다.

• 한국막학회:학술대회논문집
• /
• 한국막학회 2001년도 추계 총회 및 학술발표회(한국막학회)
• /
• pp.83-86
• /
• 2001

• 한국표면공학회지
• /
• 제29권5호
• /
• pp.443-448
• /
• 1996

In order to plasma-sulfnitride by combining ion-nitriding of a steel and sputtering of MoS$_2$, chromium-molybdenum steel was plasma-sulfritrided using hollow cathode discharge with parallel electrodes which are a main of the steel and a subsidiary cathode of $MoS_2$. The treatment was carried out at 823K for 10.8ks under 665Pa in a 30% $N_2$-70% $H_2$ gas atmosphere. Plasma-sulfnitriding layers formed of the steel were characterized with EDX, XRD, micrographic structure observation and hardness measurement. A compound layer of 8-15$\mu\textrm{m}$ and nitrogen diffusion layer of about 400$\mu\textrm{m}$ were formed on the surface of plasma-sulfnitrided steel. The compound layer consisted of FeS containing Mo and iron nitrides. The nitrides of $\varepsilon$-$Fe_2_3N$ and $\gamma$'-$Fe_4N$ formed under the FeS. The thickness of compound layer and surface hardness were different with the gaps between main and subsidiary cathodes even in the same sulfnitriding temperature. The surface hardnesses after plasma-sulfnitriding were distributed from 640 to 830Hv. The surface hardness was higher in the plasma-sulfnitriding than the usual sulfnitriding in molten salt. This may be due to Mo in sulfnitriding layer.