Vacuum degree effects on betavoltaics irradiated by ⁶³Ni with differently apparent activity densities

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• 作者：YunPeng Liu ; ZhiHeng Xu ; Hao Wang ; XiaoBin Tang
• 关键词：vacuum degree ; betavoltaic ; apparent activity density ; energy conversion unit ; MCNP5
• 刊名：Science China Technological Sciences
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：60
• 期：2
• 页码：282-288
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Engineering, general;
• 出版者：Science China Press
• ISSN：1869-1900
• 卷排序：60

文摘

For many current betavoltaics, beta sources and PN junction energy conversion units are separated. The air gap between the two parts could stop part of decay beta particles, which results in inefficient performance of the betavoltaic. By employing 63Ni with an apparent emission activity density of 7.26×107 and 1.81×108 Bq cm−2, betavoltaic performance levels were calculated at a vacuum degree range of 1×105 to 1×10−1 Pa and measured at 1.0×105 and 1.0×104 Pa, respectively. Results show that betavoltaic performance levels improve significantly as the vacuum degree increases. The maximum output power (P_max) exhibits the largest change, followed by short-circuit current (I_sc), open-circuit voltage (V_oc), and fill factor. The vacuum degree effects on I_sc, V_oc, and P_max of the betavoltaic with low apparent activity density 63Ni are more significant than those of the betavoltaic with high apparent activity density 63Ni. Moreover, the improved efficiencies of the measured performances are larger than the calculated efficiencies because of the low ratio of I_sc and reverse saturation current (I₀). The values of I₀, ideality factor, and shunt resistance were estimated to modify the equivalent circuit model. The calculation results based on this model are closer to the measurement results. The results of this research can provide a theoretical foundation and experimental reference for the study of vacuum degree effects on betavoltaics of the same kind.