• Title/Summary/Keyword: Helium

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Cooling performance test of neon refrigeration system using commercial helium compressor (상용 헬륨압축기를 이용한 네온 냉각 시스템의 냉각특성 실험)

  • Ko, Jun-Seok;Kim, Hyo-Bong;Yeom, Han-Kil;Hong, Yong-Ju;Park, Seong-Je;Lee, Kong-Hoon
    • Progress in Superconductivity and Cryogenics
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    • v.13 no.3
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    • pp.36-41
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    • 2011
  • This paper describes experimental investigation on neon refrigeration system using commercial helium compressor. In this paper, neon refrigeration cycle is calculated with assumption of ideal heat exchanger. From analysis, 32.6 K of the lowest temperature and 0.945 of quality after expansion are predicted. Cryogenic heat exchangers for pre cooler and main heat exchanger are designed and fabricated with configuration of tube-in-tube heat exchanger. In experiments, cooling performance test are performed as variation of charging pressure and orifice hole diameter. From experimental results, the lowest temperature of 44.0 K was measured with 500 ${\mu}m$ orifice and 1500 kPa of charging pressure.

Hydrogen Isotopes Accountancy and Storage Technology (수소동위원소 계량·공급기술)

  • Koo, Dae-Seo;Chung, Hong-Suk;Chung, Dong-You;Lee, Jung-Min;Yun, Sei-Hun;Cho, Seung-Yon;Jung, Ki-Jung
    • Journal of Hydrogen and New Energy
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    • v.23 no.1
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    • pp.49-55
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    • 2012
  • Hydrogen isotopes accountancy and storage are important functions in a nuclear fusion fuel cycle. The hydrogen isotopes are safely stored in metal hydride beds. The tritium inventory of the bed is determined from the decay heat of tritium. The decay heat is measured by circulating helium through the metal hydride bed and measuring the resultant temperature increase of the helium flow. We are reporting our preliminary experimental results on the hydrogen isotopes accountancy and storage performance in a metal hydride bed.

Analysis of Propellant Feeding Sub-Systems for Liquid Rocket (SINDA/FLUINT를 활용한 발사체 추진기관 공급계 해석)

  • Cho, Nam-Kyung;Jeong, Yong-Gahp;Han, Sang-Yeop;Kim, Young-Mog
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.241-244
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    • 2006
  • The analysis of propellant feeding sub-system is performed using a commercial code SINDA/FLUINT, the comprehensive finite-difference, one-dimensional, lumped parameter tool. With the code, cryogenic helium supply system, liquid oxygen supply system, helium injection cooling system are evaluated. The code gave satisfactory estimation scheme for propulsion system characterized by cryogenic temperature and high pressure, two phase flow. This paper focuses on presenting calculation scheme of propulsion sub-system using one-dimensional code like SINDA/FLUINT.

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A Study on the Non-destructive Inspection for End Closure Welding of Nuclear Fuel Elements for the Irradiation Test (조사시험용 핵연료봉 용접부 비파괴검사에 관한 연구)

  • 김웅기;김수성;이철용;이도연;이정원
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.302-304
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    • 2004
  • Nuclear fuel elements containing dry recycling nuclear fuel pellets for the irradiation test in a reactor were remotely fabricated from spent PWR fuel materials in a hot cell. End closure welding as well as seal tube welding for thermal sensor of the elements was performed by Nd:YAG laser. The soundness of the end closure welds and seal tube welds for the elements were evaluated by a precise X-ray inspection system composed of a micro-focus X-ray generator with an image intensifier and a real time camera system. Then, helium leak test was performed for the elements. The soundness of the welds of the fuel elements was confirmed by the X-ray inspection and helium leak test. The irradiation test for the fuel elements were successfully completed at the HANARO research reactor.

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HIGH-ENERGY SOLAR PARTICLE EVENTS IN THREE DIMENSIONS

  • Kocharov, Leon
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.2
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    • pp.45.1-45.1
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    • 2010
  • Using SOHO particle and EUV detection and radio spectrograms from both ground-based and spaceborne instruments, we have studied the first phase of major solar energetic particle (SEP) events associated with wide and fast coronal mass ejections (CMEs) centered at different solar longitudes. Observations support the idea that acceleration of SEPs starts in the helium-rich plasma of the eruption's core well behind the CME leading edge, in association with coronal shocks and magnetic reconnection caused by the CME liftoff; and those "coronal" components dominate during the first ~1.5 hour of the SEP event, not yet being hidden by the CME-bow shock in solar wind. At magnetic connection to the eruption's periphery, onset of SEP emission is delayed for a time of the lateral expansion that is visualized by global coronal (EIT) wave. The first, "coronal" phase of SEP acceleration is followed by a second phase associated with CME-driven shock wave in solar wind, which accelerates high-energy ions from a helium-poor particle population until the interplanetary shock slows down to below 1000 km/s. Based on these and other SOHO observations, we discuss what findings can be expected from STEREO in the SOHO era perspective.

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The Microstructure of the Reaction -Bonded $Si_3N_4$ Formed in the Various Atmosphere (질화분위기에 따른 반응결합 질화규소의 미세구조변화)

  • 박지연;김종희
    • Journal of the Korean Ceramic Society
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    • v.23 no.5
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    • pp.61-66
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    • 1986
  • The gas mixtures ($H_2$/$N_2$, He/$N_2$) having a high thermal conductivity allow the heat generated by the nitriding exotherm to be dissipated from the compact in to the nitriding atmosphere permitting a more accurate control of temperature and produces a more uniform microstructure. In order to observe the effect of the mixed gas atmosphere on the microsturcture of RBSN. the specimen was nitrided in the mixed gas atmosphere which was containe up to 50vol% $H_2$ or He for 0-12 hrs at 135$0^{\circ}C$. The addition of hydrogen to nitrogen gas resulted in the growth of a-needle at the early stage of nitrding increase of the reaction rate and a finer and more uniform microstructure. in case of the addition of helium the behaviour of reaction was similar to the one with pure nitrogen. As the amount of helium was increased a coarse microstructure was formed.

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Characteristic study of hermetic package for RF MEMS switch (RF MEMS 스위치 적용을 위한 밀봉성 패키지의 특성 연구)

  • Bang, Yong-Seung;Kim, Jong-Man;Kim, Yong-Sung;Kim, Jung-Mu;Kim, Yong-Kweon
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1464-1465
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    • 2008
  • In this paper, we compared the mechanical characteristics between LTCC-based RF MEMS packaging structures fabricated using two different types of bonding materials; BCB and gold-tin. The BCB-based packages showed an average shear strength of 32.1 MPa and helium leak rate of $1.76{\times}10^{-8}atm{\cdot}cc/sec$ for a cavity volume of $0.45\times10^{-3}cc$, while the packages bonded by gold-tin layer (80 wt.% gold, 20 wt.% tin) showed an average shear strength of 42.70 MPa and helium leak rate $1.38{\times}10^{-8}atm{\cdot}cc/sec$ for a cavity volume of $1.21{\times}10^{-3}cc$.

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The effect of addition of noble gases on negative hydrogen ion production in a dc filament discharge

  • James, B.W.;Curran, N.P.;Hopkins, M.B.;Vender, D.
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 1999.11a
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    • pp.40-45
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    • 1999
  • The effect of the addition of helium, neon, argon and xenon on the production of negative hydrogen ions has been studied in a magnetically confined dc filament discharge. The addition of helium and neon produced effects similar to an equivalent increase in hydrogen pressure. However, the addition of argon and low fractions of xenon produced significant increases in the negative ion density for hydrogen at pressures around 1 mTorr. The addition of argon and xenon, by increasing electron density and decreasing electron temperature, achieved conditions closer to optimum for negative ion production. The largest enhancement of negative hydrogen ion density occurred with the addition of argon; it is suggested that this is due to a resonant energy exchange between excited argon atoms and hydrogen molecules.

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Development of a Monitoring and Control System in Gas Purification Process (가스 정제공정의 감시 제어시스템 연구)

  • 조택선;양종화
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.313-317
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    • 1996
  • This work deals with description of gas purifing system to product high pure helium gas using low temperature absorption. The system controls temperature of heaters, open/close of solenoid valves and levels of liquid nitrogen to purify a raw gas and continuously products purified gas with perfoming alternatively purification and regeneration. We develop the monitoring and control program to monitor the gas purification process on real-time and control the process time with checking the impurities in purified gas. From the result of system operation, the developed monitoring and control system continuously products high pure helium gas with reducing impurities in raw gas to permitted limits(less than 0.01 ~ 0.05 ppm)

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Fabrication of RRR Measuring System for Disseminating IEC International Standard (IEC국제규격을 보급하기 위한 RRR측정장치 제작)

  • Kyu Won Lee;Kyu Tae Kim
    • Progress in Superconductivity
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    • v.4 no.1
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    • pp.80-85
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    • 2002
  • In order to disseminate the IEC international standard of RRR measurement of Cu/Nb/-Ti composite superconductors, a measuring system was developed at KRISS. The system consisted of helium reservoir, base plate, thermometer, voltmeter and current source. The helium reservoir and base plate provided a stable temperature of a range from 4.2 K to 300 K and the voltmeter measured several order of $mutextrm{V}$ on specimen for obtaining RRR of the Cu/Nb-Ti composite superconductor. Three specimens of the Cu/Nb-Ti composite superconductors were measured using this system for characterizing their RRR. The resistance-temperature curves ortho specimens showed 10/sup -6/ to 10/sup -5/ Ohms near transition temperature and 10/sup -4/ to 10/sup -3/ Ohms at 293 K. The RRR values of the specimens were 145, 71 and 140, respectively.

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