Vacuum Products Instruments Co.

Yamanashi, Japan

Vacuum Products Instruments Co.

Yamanashi, Japan
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Suzuki A.,Japan National Institute of Advanced Industrial Science and Technology | Hojo H.,Vacuum Products Co. | Kobayashi T.,Vacuum Products Instruments Co.
Journal of the Vacuum Society of Japan | Year: 2014

The influence of atmospheric humidity on the output of a quartz friction pressure gauge (Q-gauge) was investigated because the viscosity and molecular weight of water, which is the source of humidity, are signiĉantly smaller than those of air; therefore, they aŠect the Q-gauge output. In the temperature range of 10-50°C, the nominal pressure from the Q-gauge decreased by approximately several percent owing to relative humidity, which was higher than the lower explosive limit of hydrogen, and this may cause an error in hydrogen sensing. The Q-gauge output was pressure-calibrated using its humidity dependence, and therefore, the diŠerence in the pressure-calibrated Q-gauge output (Q-gauge ratio) between 0 and 100% humidity was reduced to 1% of the Q-gauge ratio. It was indicated that the inInfluence of humidity can be excluded by calibrating the Q-gauge output using the humidity dependence necessary for the outdoor use of that type of hydrogen sensor.


Suzuki A.,Japan National Institute of Advanced Industrial Science and Technology | Hojo H.,Vacuum Products Co. | Kobayashi T.,Vacuum Products Instruments Co.
Journal of the Vacuum Society of Japan | Year: 2013

This study focused on the eFFect of temperature on a quartz friction pressure gauge, which uses a quartz oscillator as a sensor, for hydrogen sensing at room temperature. The temperature dependence of the nominal pressure and of the impedance and resonance frequency of the quartz oscillator were measured. The nominal pressure was found to depend on both the temperature and relative humidity in the range 0-100%, indicating the necessity for calibration. In contrast, the resonance frequency of the quartz oscillator was found to exhibit a linear dependence on temperature and to be independent of the relative humidity at atmospheric pressure. Thus, it can be used as an indicator of the temperature in order to calibrate the nominal pressure measured by the pressure gauge.


Kurokawa A.,Japan National Institute of Advanced Industrial Science and Technology | Hojo H.,Vacuum Products Co. | Kobayashi T.,Vacuum Products Instruments Co.
Journal of the Vacuum Society of Japan | Year: 2011

The vibrating quartz oscillator in the viscous-flow gas was observed to compare the pressure (P) dependence between the im pedance change (DZ) and the frequency change (DF). We obtained the DZ and the DF for Ar, O 2, and Ne gases. Among Ar and O 2 both the DZs and the DFs had no intersection with each other. However, Ne gas had the intersections with Ar gas with the DZ (P) and with O 2 for the DF(P). The phenomenon was caused by the Ne property which Ne has smaller mass but larger viscosity compared with Ar and O 2. The AZ-AF property showed that the property of each gas lied in the viscosity descending order, i.e., Ne, Ar, O 2. The measurement of (DZ, DF) property could give the viscosity related information.


Suzuki A.,Japan National Institute of Advanced Industrial Science and Technology | Hojo H.,Vacuum Products Co | Kobayashi T.,Vacuum Products Instruments Co
Vacuum | Year: 2015

For outdoor hydrogen sensing using a quartz friction pressure gauge (Q-gauge), we investigated the influence of ambient temperature on the output from a Q-gauge, because the change in the baseline of the Q-gauge output might be comparable in degree to the changes resulting from hydrogen leakage, which results in an error for hydrogen sensing. At constant relative humidity, the output from the Q-gauge changed with the change in temperature within the range 15-50 °C. The largest differences in the output with respect to temperature corresponded to those seen in hydrogen leakage with about 6 vol% hydrogen concentration, judging from the correlation between the change in the Q-gauge and hydrogen concentration. 6 vol% hydrogen concentration is clearly higher than the necessary minimum for detection of hydrogen concentration because one-fourth of the low explosive level hydrogen concentration is 1 vol%; therefore, temperature calibration is necessary for outdoor use of this hydrogen sensing method. We tried to suppress the influence of temperature on the Q-gauge output using the temperature dependence of the experimental output. We found that the influence of temperature could be reduced to change the output by less than 1 vol% hydrogen concentration. © 2015 Elsevier Ltd.All rights reserved.


Suzuki A.,Japan National Institute of Advanced Industrial Science and Technology | Suzuki A.,National Metrology Institute of Japan | Hojo H.,Vacuum Products Co. | Kobayashi T.,Vacuum Products Instruments Co.
Journal of the Vacuum Society of Japan | Year: 2015

Measurements of silane concentration using a quartz friction pressure gauge (Q-gauge) in gas mixtures of hydrogen and silane were applied to the region of low pressure and low silane concentration. The measured conditions of pressures below 100 Pa and silane concentrations below 10 vol% are important because they are usually used for microcrystalline silicon film deposition in production of thin silicon solar cells. Output from the Q-gauge depended on silane concentration of 1-100 vol% in the gas mixtures at a constant pressure of 13 Pa and on silane concentrations of 1, 2, 3, 5, and 7 vol% in the gas mixtures at 13-1333 Pa. Present partial concentration measurement using the Q-gauge was shown to be applicable to gas mixtures of silane and hydrogen even at low pressures and low silane concentrations. © 2015 Journal of the Vacuum Society of Japan.


Suzuki A.,Japan National Institute of Advanced Industrial Science and Technology | Suzuki A.,National Metrology Institute of Japan | Hojo H.,Vacuum Products Co. | Kobayashi T.,Vacuum Products Instruments Co.
Journal of the Vacuum Society of Japan | Year: 2015

A novel quartz oscillator that has a temperature-stable output was investigated for outdoor hydrogen sensing. The output from the quartz oscillator remained almost constant for temperatures in the range of 15 to 50°C. Fluctuations of the output of the quartz oscillator in this temperature range were 0.3% at constant relative humidity of 0%RH, which corresponds to the change in the output when 0.3 vol% of hydrogen leaked in air. This change is thus suffciently lower than the necessary minimum detection level of 1 vol% hydrogen concentration using the novel quartz oscillator's output during outdoor hydrogen sensing. © 2015 Journal of the Vacuum Society of Japan.


Kurokawa A.,Japan National Institute of Advanced Industrial Science and Technology | Hojo H.,Vacuum Products Corporation | Kobayashi T.,Vacuum Products Instruments Co.
Applied Physics Express | Year: 2011

We demonstrate that a quartz resonator vibrating in a viscous flowing gas has two independent outputs, which are an impedance change δZ( p) and a frequency change δF(ρ), where ρ is gas pressure. Observations of δZ(ρ) and δF(ρ) for N 2, O 2, Ar, and Ne gases show that the δZ-δF plots for all of the gases have no intersections with each other for pressures between 0.16 to 120 kPa. We derive a simple expression for the δZ-δF relation, which enables the evaluation of the gas viscosity from measurements of δZ and δF regardless of gas pressure. © 2011 The Japan Society of Applied Physics.


Kurokawa A.,Japan National Institute of Advanced Industrial Science and Technology | Itoh M.,Japan National Institute of Advanced Industrial Science and Technology | Terauchi S.,Japan National Institute of Advanced Industrial Science and Technology | Hojo H.,Vacuum Products Co. | Kobayashi T.,Vacuum Products Instruments Co.
Journal of the Vacuum Society of Japan | Year: 2013

The effect of exposure to ozone on the frequency shift (ΔF) and pressure (P) of a quartz oscillator was observed to check its resistance against the gas. After every ozone exposure, the ΔF-P characteristic curves shifted toward lower frequencies, indicating that the oscillator lost its repeatability. The oscillator electrode consisted of an Au-Cr film deposited on a quartz substrate; an evaluation using a scanning electron microscope (SEM) showed that each film layer had a thickness of 65 nm. The surface composition of the electrode was analyzed by Auger electron spectroscopy (AES). The AES intensities of Cr and Au showed that Cr oxide was present on top of the Au film layer; we speculate that ozone exposure may proceed the Cr oxidation with higher atomic valence. AES depth analysis showed that a small amount of Cr was detected in the Au film layer; we believe that Cr oxidation could progress by either Cr diffusion through the Au layer or by O diffusion from the surface.

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