• Title/Summary/Keyword: Vacuum measurement

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Study on the Measurement of TMP Pumping Speed (터보분자펌프(TMP) 배기속도 측정에 관한 고찰)

  • Kang, S.B.;Shin, J.H.;Cha, D.J.;Koh, D.Y.;Cheung, W.S.;Lim, J.Y.
    • Journal of the Korean Vacuum Society
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    • v.19 no.4
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    • pp.249-255
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    • 2010

  • Methods of the characteristics evaluation of turbo-molecular pumps (TMP) are well-defined in the international measurement standards such as ISO, PNEUROP, DIN, JIS, and AVS. The Vacuum Center in the Korea Research Institute of Standards and Science (KRISS) has recently designed, constructed, and established the integrated characteristics evaluation system of TMPs based on the international documents by continuously pursuing and acquiring the reliable international credibility through measurement perfection. The measurement of TMP pumping speed is normally performed with the throughput and orifice methods dependent on the mass flow regions. However, in the UHV range of the molecular flow region, the high uncertainties of the gauges, mass flow rates, and conductance are too critical to precisely accumulate reliable data. In order to solve the uncertainty problems of pumping speeds in the UHV range, we introduced a SRG with 1% accuracy and a constant volume flow meter (CVFM) to measure the finite mass flow rates down to $10^{-1}$ Pa-L/s with 3% uncertainty for the throughput method. In this way we have performed the measurement of pumping speed down to $10^{-4}$ Pa with an uncertainty of less than 6% for a 1000 L/s TMP. In this article we suggest that the CVFM has an ability to measure the conductance of the orifice experimentally with flowing the known mass through the orifice chambers, so that we may overcome the discontinuity problem encountering during introducing two measurement methods in one pumping speed evaluation sequence.

  • https://doi.org/10.5757/JKVS.2010.19.4.249 인용 PDF KSCI

Development of Digital Vacuum Pressure Sensor Using MEMS Analog Pirani Gauge

  • Cho, Young Seek
    • Journal of information and communication convergence engineering
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    • v.15 no.4
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    • pp.232-236
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    • 2017

  • A digital vacuum pressure sensor is designed, fabricated, and characterized using a packaged MEMS analog Pirani gauge. The packaged MEMS analog Pirani gauge requires a current source to heat up a heater in the Pirani gauge. To investigate the feasibility of digitization for the analog Pirani gauge, its implementation is performed with a zero-temperature coefficient current source and microcontroller that are commercially available. The measurement results using the digital vacuum pressure sensor showed that its operating range is 0.05-760 Torr, which is the same as the measurement results of the packaged MEMS analog pressure sensor. The results confirm that it is feasible to integrate the analog Pirani gauge with a commercially available current source and microcontroller. The successful hybrid integration of the analog Pirani gauge and digital circuits is an encouraging result for monolithic integration with a precision current source and ADCs in the state of CMOS dies.

  • https://doi.org/10.6109/jicce.2017.15.4.232 인용 PDF KSCI

Development of liquid target for beam-target neutron source & two-channel prototype ITER vacuum ultraviolet spectrometer

  • Ahn, B.N.;Lee, Y.M.;Dang, J.J.;Hwang, Y.S.;Seon, C.R.;Lee, H.G.;Biel, W.;Barnsley, R.;Kim, D.E.;Kim, J.G.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.421-422
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    • 2011

  • The first part is about development of a liquid target for a neutron source, which is designed to overcome many of the limitations of traditional beam-target neutron generators by utilizing a liquid target neutron source. One of the most critical aspects of the beam-target neutron generator is the target integrity under the beam exposure. A liquid target can be a good solution to overcome damage to the target such as target erosion and depletion of hydrogen isotopes in the active layer, especially for the one operating at high neutron fluxes with no need for water cooling. There is no inherent target lifetime for the liquid target neutron generator when used with continuous refreshment of the target surface exposed to the energetic beam. In this work, liquid target containing hydrogen has been developed and tested in vacuum environment. Potentially, liquid targets could allow a point neutron source whose spatial extension is on the order of 1 to $10{\mu}m$. And the second is about the vacuum ultraviolet (VUV) spectrometer which is designed as a five-channel spectral system for ITER main plasma measurement. To develop and verify the design, a two-channel prototype system was fabricated with No. 3 (14.4 nm~31.8 nm) and No. 4 (29.0 nm~60.0 nm) among the five channels. For test of the prototype system, a hollow cathode lamp is used as a light source. The system is composed of a collimating mirror to collect the light from source to slit, and two holographic diffraction gratings with toroidal geometry to diffract and also to collimate the light from the common slit to detectors. The two gratings are positioned at different optical distances and heights as designed. To study the appropriate detector for ITER VUV system, two different electronic detectors of the back-illuminated charge coupled device and the micro-channel plate electron multiplier were installed and the performance has been investigated and compared in the same experimental conditions. The overall system performance was verified by measuring the spectrums.

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