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AbstractA nuclear battery is a promising candidate for small power supply sources in the military and commercial fields, but its output power and energy conversion efficiency need to be improved. This paper mainly describes a design, preparation, and electrical performance analysis of a GaAs-based tritium battery. The design of the tritium battery uses a multistage process with Monte Carlo and Matlab simulations. A titanium tritide source was prepared by a high-temperature tritium absorption device, and a GaAs semiconductor transducer was developed using a metal-organic chemical vapor deposition method. The D/Ti ratio and T/Ti ratio of the deuterium/tritium titanium films were 1.9 and 1.7, respectively. Two kinds of GaAs-based PIN junction semiconductor transducers were proposed and irradiated with the prepared tritium source. Their electrical properties were measured in situ and analyzed qualitatively. Under the irradiation of a 0.61-Ci tritium source, the short-circuit current of the device was 0.3 to 0.38 μA, the open-circuit voltage was 35 to 63 mV, the peak power was 2.8 to 6.4 nW, and the energy conversion efficiency of the GaAs semiconductor transducer was about 1.86%. It was found that an air gap between the GaAs semiconductor transducer and the radioactive source caused serious loss of beta particle energy, resulting in low output power and low energy conversion efficiency of the nuclear battery. The open-circuit voltage of the devices with a SiO2 passivation layer on the surface decreased both in a dark environment and in light illumination, but SiO2 passivation did not reduce surface recombination as expected. The research work in this paper will provide some valuable reference for the preparation and performance optimization of nuclear batteries. [ABSTRACT FROM AUTHOR]

AbstractA 100-W radioisotope thermoelectric generator (RTG) is by far the most suitable power supply for long-term deep space exploration where solar power would not be feasible. Understanding the thermal performance and electrical performance of the RTG under operational conditions is paramount for its nominal and safety performance during the space mission. In this paper, modeling and experimental studies on the thermal behavior and electrical performance of the 100-W RTG have been conducted. The RTG uses high conversion efficiency skutterudite-based thermoelectric convertor (TEC) arrays thermally coupled with a radioisotope heat unit (RHU) to generate electricity. A comprehensive finite element model and an electrical heating prototype of the 100-W RTG have been built to assess the performance of the RTG designs. Critical temperature, generated power, and energy conversion efficiency were evaluated. The simulation results show that the maximum output power of the RTG can reach about 120 W(electric); the temperature of the hot end of the TECs is about 853 K, and the temperature of the cold end is about 473 K, making a temperature difference of about 380 K. The RTG prototype with Bi2Te3 TECs generated about 60 W(electric) of electrical power in the first experimental research stage. These research results have significant reference for extension of the RTG prototype to the actual power source of the RHU and allow for future research and development improvements of the 100-W RTG. [ABSTRACT FROM AUTHOR]

This paper considers the estimation of parameters based on a progressively type-I interval-censored data from a mixed generalized exponential distribution. The maximum likelihood estimation is used but an analytic form cannot be obtained. The EM algorithm is applied to obtain the maximum likelihood estimates. The performance of the estimates is judged by a simulating study and a real data is presented to illustrate the method of estimation developed here. [ABSTRACT FROM AUTHOR]