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Effects of gamma-ray irradiation on Dielectric Surface Breakdown of Polybutylene Naphthalate and Polybutylene Terephthalate Under Reduced Pressure

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Transactions of Tianjin University 2007年第4期13卷 247-253页

作者：杜伯学刘弘景刘勇孟令飞 School of Electrical Engineering and Automation Tianjin University

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

关键词： polybutylene naphthalate (PBN) polybutylene terephthalate ( PBT) air pressure total dose gamma-ray irradiation discharge quantity dielectric breakdown cross-linking degradation

γ-irradiation Effect:Variation of Photosynthetic Activity of Euglena

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Biomedical and Environmental Sciences 2002年第3期15卷 261-267页

作者： T·SAKASHITA M·DOI 等 NationalInstituteofRadinologicalSciences

Objective To study the effects of gamma-ray irradiation on carbon fixation (Specific production rate: SPR), CO2 utilization efficiency (CUE) and electron transfer rate (ETR) in the photosynthetic flagellate Euglena gracilis strain Z in a dose-response dependent manner. Methods Euglena cells were cultured in an inorganic nutrient medium containing ammonium chloride or proteose peptone. Cells were exposed to gamma-ray at 5 doses (0, 100, 250, 350, 500 Gy for water). Five days after irradiation, three photosynthetic activities were measured. SPR, which is a carbon uptake rate per unit carbon mass, was determined by 13C tracer methodology. CUE was evaluated using a relation of carbon isotope fractionation in Calvin cycle. ETR in photosystem II (PS II) was measured by a chlorophyll fluorescence analysis. Results Even at a dose of 500 Gy, 80 % of ETR of the non-irradiated control (0 Gy) was sustained, while SPR and CUE were about half the level in the non-irradiated control at 500 Gy. Furthermore, the dose response of ETR was considerably different from the others. Conclusion Our findings suggest that not only PS II but also the Calvin cycle in the photosynthetic system is affected by gamma ray irradiation.

关键词： gamma-ray irradiation Euglena gracilis Photosynthetic activities

Impact of low-dose radiation on nitrided lateral 4H-SiC MOSFETs and the related mechanisms

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Chinese Physics B 2023年第5期32卷 637-643页

作者：张文浩朱马光余康华李诚瞻王俊向立王雨薇 College of Materials Science and Engineering Hunan UniversityChangsha 410082China School of Integrated Circuits Nanjing UniversitySuzhou 210008China College of Electrical and Information Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Power Semiconductor Devices Zhuzhou CRRC Times Semiconductor Co.Ltd.Zhuzhou 412001China

Lateral type n-channel 4H-SiC metal–oxide–semiconductor field effect transistors(MOSFETs),fabricated using a current industrial process,are irradiated with gamma rays at different irradiation doses in this paper to carry out a profound study on the generation mechanism of radiation-induced interface traps and oxide trapped *** parameters(e.g.,threshold voltage,subthreshold swing and channel mobility)of the device before and after irradiation are investigated,and the influence of the channel orientation([1100]and[1120])on the radiation effect is discussed for the first time.A positive threshold voltage shift is observed at very low irradiation doses(irradiation doses<100 krad,the radiation-induced interface traps with relatively high generation speeds dominate the competition with radiation-induced oxide trapped charges,contributing to the positive threshold voltage shift *** these results provide additional insight into the radiation-induced charge trapping mechanism in the SiO_(2)/SiC interface.

关键词： SiC MOSFET gamma-ray irradiation interface traps oxide-trapped charges

Spectroscopic and radiation-resistant properties of Er,Pr:GYSGG laser crystal operated at 2.79 μm

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Chinese Physics B 2017年第7期26卷 173-177页

作者：赵绪尧孙敦陆罗建乔张会丽方忠庆权聪李秀丽程毛杰张庆礼殷绍唐 The Key Laboratory of Photonic Devices and Materials Anhui Province Anhui Institute of Optics and Fine MechanicsChinese Academy of Sciences University of Science and Technology of China State Key Laboratory of Pulsed Power Laser Technology Electronic Engineering Institute

We demonstrate the spectroscopic and laser performance before and after 100 Mrad gamma-ray irradiation on an Er,Pr：GYSGG crystal grown by the Czochralski method. The additional absorption of Er,Pr：GYSGG crystal is close to zero in the 968 nm pumping and 2.7-3 μm laser wavelength regions. The lifetimes of the upper and lower levels show faint decreases after gamma-ray irradiation. The maximum output powers of 542 and 526 mW with the slope efficiencies of 17.7% and 17.0% are obtained, respectively, on the GYSGG/Er,Pr：GYSGG composite crystal before and after the gammaray irradiation. These results suggest that Er,Pr：GYSGG crystal as a laser gain medium possesses a distinguished antiradiation ability for application in space and radiant environments.

关键词： Er Pr:GYSGG crystal gamma-ray irradiation anti-radiation ability laser material