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ABSTRACT: We propose a new capture/recovery technology to reduce emissions of perfluorocompounds (PFCs) from semiconductor industry. The conventional capture/recovery technology has some problems in its repurification step. The cryogenic distillation needs a huge distillation tower and much power for refrigeration. On-site capture/recovery is not viable by the cryogenic distillation, because the system is economically feasible only with a large-scale operation. The continuous gas chromatography technology is a compact alternative to the conventional repurification method. The system is composed of the series of separation columns, vacuum pumps and automatic valves. The mixed PFCs are separated by the difference of the affinity for the column. Only the perfectly separated PFCs are output and the others are injected to the next column. By recycling the PFC mixture, which was not separated by the single column, the continuous gas chromatography outputs the pure PFCs continuously. The system is compact and it can operate with low energy consumption. Moreover, it can separate CF<sub>4 </sub> and NF<sub>3</sub>, which can not be separated by a cryogenic distillation
Semiconductor Manufacturing Symposium, 2001 IEEE International; 02/2001
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ABSTRACT: A high‐resolution quadrupole mass spectrometer (QMS) which can detect <sup>3</sup>He in HD and <sup>4</sup>He in D 2 has been developed. The QMS is equipped with two resolving powers, i.e., a high‐resolution mode and a normal one, and voltages for realizing the two modes are supplied by a common circuit. The high‐resolution mode adopts a condition of the second stability zone (zone II) in the Mathieu diagram and can analyze a range of 1–9 amu. The detectable peak ratios of <sup>3</sup>He/HD and <sup>4</sup>He/D 2 were obtained at roughly 0.1 and 10<sup>-4</sup>, respectively. The normal mode adopts the first stability zone (zone I) and has an analyzable range of 1–60 amu.
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 10/1994; · 1.25 Impact Factor
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ABSTRACT: This paper describes how a small helium (<sup>4</sup>He) peak can be separated from a large adjacent deuterium (D 2 ) peak using a modified quadrupole mass spectrometer (QMS). This QMS utilized a condition of the second stability zone (zone II) in the Mathieu diagram. The minimum detectable peak ratio of <sup>4</sup>He to D 2 was 10<sup>-4</sup> when a mass scan line was set close to the upper tip, and was 10<sup>-3</sup> when the scan line was adjusted to the lower tip. The ion transmission rates simulating the peaks were calculated for the upper and lower zone conditions. It was found that a longer peak tail occurs when an unstable orbit has mainly a cosh function. From the experimental and theoretical data, it is concluded that the upper zone condition is the most suitable for realizing a high‐resolution peak.
Review of Scientific Instruments 07/1994; · 1.37 Impact Factor
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ABSTRACT: A quadrupole mass spectrometer (QMS) with a specially designed analyzing head which was movable in a dynamic vacuum system was fabricated and the performance was tested. The head comprises a collimator and an airtight casing containing a rf tuning and its detection circuit. The rf circuit is tuned by supplying variable frequency of the rf voltage since the resonance frequency depends weakly on environmental temperature. This QMS can be obtain a normal mass spectrum for a mass range 1–50 amu even when the vessel is baked to 150 °C. The measured pressure rise of Ar is 1.08×10<sup>-5</sup> Pa at a distance of 125 mm from the effusing nozzle of argon gas with a flow rate of 1.9×10<sup>-5</sup> Pa m<sup>3</sup> s<sup>-1</sup>, which is two times as large as the calculated value.
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 02/1991; · 1.25 Impact Factor
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ABSTRACT: A water leak detection method using krypton (Kr) as a water-soluble tracer has been proposed for fusion reactors with fully circulating the in-vessel cooling water. This method was targeted for applying to the International Thermonuclear Experimental Reactor (ITER), and the 10−3 Pa m3/s order of water leak valves were fabricated and connected to the water loop circuit. The water leaks were effused into the vacuum vessel evacuated by a cryopump and the water dissolved Kr was detected by a quadrupole mass spectrometer (QMS). When two leak valves with 1 m distance were attached to the test pipe with 30 °C heating, two distinct, the mass to charge number ratio (m/e) of 84 peak current rises caused by the water leak were successfully detected with the time interval of 39 s. On the other hand, the water accession length as a function of the traveling time was calculated by considering a natural convection flow caused by the 30 °C heating, where the traveling time was 44.6 s for the 1 m length. This means that the observed positional accuracy is 12.6%, based on the calculation. To enhance the positional accuracy, the detailed flow simulation is indispensable. This method can be applied to the ITER condition.
Fusion Engineering and Design. 83(1):72-78.
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ABSTRACT: In fusion machines, realizing a high-purity plasma is a key to improving the plasma parameters. Thus, leak detection is a necessary part of reducing the leak rate to a tolerable level. However, a conventional helium (4He) leak detector is useless in fusion machines with a deuterium (D2) plasma, because retained D particles on the first walls release D2 for a long period and the released D2 interferes with the signals from the leaked 4He due to the near identical masses of 4.0026 u (4He) and 4.0282 u (D2). A high-resolution quadrupole mass spectrometer (HR-QMS) that we have recently developed, can detect a 4He+ population as small as 10−4 peak in a D2 atmosphere. Thus, the HR-QMS has been applied to detect 4He leaks. To improve the minimum detectable limit of 4He leak, a differentially pumped HR-QMS analyzer was attached to a chamber of the 4He leak detector. In conclusion, the improved 4He leak detector could detect 4He leaks of the order of 10−10 Pa · m3/s in a D2 atmosphere.
Vacuum.
