• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.167-167
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• 2004

반도체 공정 등에서 10-6_10-8 TOW의 고진공 환경을 제공하기 위하여 사용되는 고진공 터보분자펌프(Turbomolecular Pump, TMP)는 다층의 회전깃을 갖는 로터를 회전시켜 분자를 배출시키는 방식을 사용하는 진공펌프이다. 이러한 고진공을 실현하기 위해서는 가장 효과적인 방법으로는 회전블레이드의 선속도를 높이는 것으로, 이는 회전로터의 직경을 크게 하거나, 회전속도를 높임으로써 얻어질 수 있다. 따라서 최근의 고진공 터보분자펌프는 대부분 25,000∼40,000RPM의 고속회전을 요구하는 것이 일반적이며 회전속도는 주로 로터 재료의 허용한도까지 적용되고 있다.(중략)

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.1-4
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• 1998

We have developed an extreme high vacuum (XHV) system using a new combination pump cpmposed of a suitably shaped NEG(Non-Evaporable Getters) in the body of a sputter-ion pump (SIP). The stainless-steel test chamber was used which had been well oxidized at $450^{\circ}C$ and already yielded XHV with a turbomolecular pumping system. The pressure was measured by a Leybold extractor gauge (EXG,limit:1~$2{\times}10^{-12}$torr, but in the ultimate pressure regionthe EXG shows an unusual sign as $-0.{\times}10^{-12}$ torr which indicates much lower pressure range than its available lower limit. These results are mainly due to the high pumping speed of NEG for hydrogen. Furthermore, use of the SIP combined with the NEG as a XHV pumping system implies the potential for actualization of the surface analysis under XHV environment, and allows one to have a chance tp meet a new world in nanometer science and technology.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.625-630
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• 2000

Numerical and experimental investigations are peformed for the rarefied gas flows in pumping channels of a helical-type drag pump. Modern turbomolecular pumps include a drag stage in the discharge side, operating roughly in $10^{-2}{\sim}10Torr$. The flow occurring in the pumping channel develops from the molecular transition to slip flow traveling downstream. Two different numerical methods are used in this analysis: the first one is a continuum approach in solving the Navier-Stokes equations with slip boundary conditions, and the second one is a stochastic particle approach through the use of the direct simulation Monte Carlo(DSMC) method. The flow in a pumping channel is three-dimensional(3D), and the main difficulty in modeling a 3D case comes from the rotating frame of reference. Thus, trajectories of particles are no longer straight lines. In the Present DSMC method, trajectories of particles are calculated by integrating a system of differential equations including the Coriolis and centrifugal forces. Our study is the first instance to analyze the rarefied gas flows in rotating frame in the presence of noninertial effects.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.359-365
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• 2006

Since the start of the KSTAR (Korea Superconducting Tokamak Advanced Research) project, Instrumentation and Control (I&C) of the Neutral Beam Test Facility (NB-TF) has been striving to answer diverse requests arising from various facets during the project's development and construction phases. Hard-wired electrical circuits have been designed, tested, fabricated, and finally installed to the relevant parts of the system. In relation to the vacuum system I&C, controlling functions for the rotary pumps, a Roots pump, two turbomolecular pumps, and four cryosorption pumps have been constructed. I&C for the ion source operation are the temperature and flow rate signal monitoring, Langmuir probe signal measurements, gradient grid current measurements, and arc detector circuit. For the huge power system to be monitored or safely operated, many temperature measurement functions have also been implemented for the beam line components like the neutralizer, bending magnet, ion dump, and calorimeter. Nearly all of the control and probe signals between the NB test stand and the control room were made to be transmitted through the optical cables. Failures of coolant flow or beam line vacuum pressure were made to be safely blocked from influencing the system by an appropriate interlock circuit that will shut down the extraction voltage application to the system or prevent damages to the vacuum components. Preliminary estimation of the beam power through the calorimetric measurement shows that 87.9% of the total power of the 60kV/18A beam with 200 seconds duration is absorbed by the calorimeter surface. Most of these I&C results would be highly appropriate for the construction of the main NBI facility for the KSTAR national fusion research project.