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Misawa, Japan

Sasaki H.,Japan National Institute of Advanced Industrial Science and Technology | Yamamori H.,Japan National Institute of Advanced Industrial Science and Technology | Yamada T.,Japan National Institute of Advanced Industrial Science and Technology | Fujiki H.,Japan National Institute of Advanced Industrial Science and Technology | And 3 more authors.
IEEE Transactions on Instrumentation and Measurement | Year: 2010

We are developing a programmable Josephson voltage standard (PJVS) system based on a compact cryocooler. The system is capable of generating two arbitrary waveforms by use of a dual-output PJVS (DO-PJVS) device. Owing to this dual-output feature of the PJVS system, the low-frequency characteristic in the acdc transfer difference of a thermal converter has been investigated using the 90° addition method. The evaluation of the low-frequency characteristic of a thermal converter is of great importance for connecting conventional acdc transfer standards and new Josephson-based ac voltage standards. To fulfill this purpose, a dual-heater thermal voltage converter (DH-TVC) with improved low-frequency performance has been developed. The low-frequency acdc transfer difference of the DH-TVC was evaluated to be smaller than 1 μV/V at frequencies of as low as 1 Hz. © 2010 IEEE. Source


Amaga Y.,Japan National Institute of Advanced Industrial Science and Technology | Fujiki H.,Japan National Institute of Advanced Industrial Science and Technology | Shimizume K.,Japan National Institute of Advanced Industrial Science and Technology | Hidaka S.,Nikkohm Co.
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) | Year: 2014

We have demonstrated the long-term stability and environmental durability of a high-performance thin-film multijunction thermal converter (TMJTC) with an improved thin-film thermopile design. We fabricated a new TMJTC with an improved deposition pattern for a Bi-Sb-Cu-based thin-film thermopile in order to avoid interface delamination between the Bi and the Cu layers. Our TMJTC exhibited good frequency properties, with an ac-dc difference of less than 5 μV/V in the range from 10 Hz to 100 kHz, at a root-mean-square (rms) voltage of 10 V. The long-term stability of the TMJTC has been significantly increased owing to the performance of the developed thin-film thermopile, as compared with that of previously fabricated TMJTCs, exhibiting an ac-dc difference of less than 2 μV/V after 18 months at room temperature. We also evaluated the temperature, relative humidity, and pressure characteristics of the TMJTC in accordance with the International Electrotechnical Commission (IEC) standards for electronic devices. The measurement results showed that the dependence of the ac-dc transfer difference on the temperature, humidity, and pressure was less than 1 μV/V, which is comparable to the results of thermal converters, constituting the primary standard. © 2014 Wiley Periodicals, Inc. Source


Amagai Y.,Japan National Institute of Advanced Industrial Science and Technology | Fujiki H.,Japan National Institute of Advanced Industrial Science and Technology | Shimizume K.,Nikkohm Co. | Kishino K.,Nikkohm Co. | Hidaka S.,Nikkohm Co.
CPEM Digest (Conference on Precision Electromagnetic Measurements) | Year: 2014

We have evaluated the AC-DC transfer differences of our thin-film multijunction thermal converters with increased heat capacity under vacuum conditions to improve the low frequency characteristics. The measured thermal time constant at about 0.001 Pa is increased up to 9 s from 3 s measured at ambient pressure. The AC-DC transfer differences evaluated by using a sampling method are less than 1 μV/V down to 10 Hz, and 10 μV/V down to 0.2 Hz, which is about ten times smaller compared with those obtained at ambient pressure. © 2014 IEEE. Source


Amagai Y.,Japan National Institute of Advanced Industrial Science and Technology | Fujiki H.,Japan National Institute of Advanced Industrial Science and Technology | Shimizume K.,Nikkohm Co. | Kishino K.,Nikkohm Co. | Hidaka S.,Nikkohm Co.
IEEE Transactions on Instrumentation and Measurement | Year: 2015

We have improved the ac-dc transfer differences and enhanced the sensitivity in our thin-film multijunction thermal converters (TFMJTCs) in vacuum. The ac-dc transfer differences of the TFMJTCs are less than 1 μV/V down to 1 Hz and 10 μV/V down to 0.2 Hz owing to the increased thermal time constant. The measured output voltage exceeds 120 mV at 10-4 Pa owing to the reduction of heat conduction to the air. The sensitivity of the device, defined as the ratio of the output voltage to the input power, is 2.4 V/W, which is approximately three times larger than that measured at ambient pressure. Numerical simulations of the heat transfer of our TFMJTC explain the experimental results well. © 1963-2012 IEEE. Source


Fujiki H.,Japan National Institute of Advanced Industrial Science and Technology | Amagai Y.,Japan National Institute of Advanced Industrial Science and Technology | Shimizume K.,Nikkohm Co. | Kishino K.,Nikkohm Co. | Hidaka S.,Nikkohm Co.
IEEE Transactions on Instrumentation and Measurement | Year: 2015

To increase the long-term stability of thin-film multijunction thermal converters (TFMJTCs) developed by the National Metrology Institute of Japan and Nikkohm Corporation Ltd., we prevented their degradation by improving the design and fabrication process. Judging from the Arrhenius model experiments, we successfully increased the lifetime of a renewed TFMJTC to more than 20 years by improving the deposition pattern of a Bi-Sb-Cu-based thin-film thermopile. We also evaluated the thermoelectric effect of the renewed TFMJTCs by the fast-reversed dc method. The low thermoelectric effect of less than 0.1 μV/V has been realized, which is comparable with that of high-quality multijunction thermal converters previously produced by other national metrology institutes. © 1963-2012 IEEE. Source

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