Measurement uncertainties for vacuum standards at Korea Research Institute of Standards and Science

Abstract

The Korea Research Institute of Standards and Science has three major vacuum systems: an ultrasonic interferometer manometer (UIM) (Sec. II, Figs. 1 and 2) for low vacuum, a static expansion system (SES) (Sec. III, Figs. 3 and 4) for medium vacuum, and an orifice-type dynamic expansion system (DES) (Sec. IV, Figs. 5 and 6) for high and ultrahigh vacuum. For each system explicit measurement model equations with multiple variables are, respectively, given. According to ISO standards, all these system variable errors were used to calculate the expanded uncertainty (U). For each system the expanded uncertainties (k=1, confidence level=95%) and relative expanded uncertainty (expanded uncertainty/generated pressure) are summarized in Table IV and are estimated to be as follows. For UIM, at 2.5–300Pa generated pressure, the expanded uncertainty is <4.17×10−2Pa and the relative expanded uncertainty is <1.18×10−2; at 1–100kPa generated pressure, the expanded uncertainty is <7.87Pa and the relative expanded uncertainty is <7.84×10−5. For SES, at 3–100Pa generated pressure, the expanded uncertainty is <1.77×10−1Pa and the relative expanded uncertainty is <1.81×10−3. For DES, at 4.6×10−3–1.3×10−2Pa generated pressure, the expanded uncertainty is <1.04×10−4Pa and the relative expanded uncertainty is <8.37×10−3; at 3.0×10−6–9.0×10−4Pa generated pressure, the expanded uncertainty is <8.21×10−6Pa and the relative expanded uncertainty is <1.37×10−2. Within uncertainty limits our bilateral and key comparisons [CCM.P-K4 (10Pa–1kPa)] are extensive and in good agreement with those of other nations (Fig. 8 and Table V).

Final report of key comparison CCM.P-K3: absolute pressure measurements in gas from 3 × 10−6Pa to 9 × 10−4Pa

“…The HV system is evacuated using a turbomolecular pump with a pumping speed for nitrogen of 345 L/s, and the UHV system is evacuated using a closed loop helium refrigerator-type cryopump with a pumping speed for nitrogen of 1500 L/s. Further details of the systems and a full uncertainty analysis are given in [8].…”

The development of vacuum measurements down to extremely high vacuum – XHV

“…For the XHV calibrations for the moment the only possibility is connected with the use of the continuous expansion method with gas flow divider [95,105]. But even with flow divider the primary systems do not cover the full measuring range of all available ionization gauges.…”

Calibration of Capacitance Diaphragm Gauges with 1333 Pa full scale by Direct Comparison to Resonant Silicon Gauge and Static Expansion System

“…In such a case, the validity of the interpolation should be confirmed. A capacitance diaphragm gauge with 1333 Pa full scale (CDG-10Torr) is used for precise pressure measurements in the range from 1 Pa to 10 3 Pa. For the calibration of the CDG-10Torr at least four candidate techniques are available: pressure balance, static expansion system (SES) [1][2][3][4][5], force-balanced piston gauge [6,7], and oil manometer [5,8,9].…”