In the present paper we conduct a theoretical study of the thermal accumulation effect of a typical bipolar transistor caused by high power pulsed microwaves(HPMs),and investigate the thermal accumulation effect as ...In the present paper we conduct a theoretical study of the thermal accumulation effect of a typical bipolar transistor caused by high power pulsed microwaves(HPMs),and investigate the thermal accumulation effect as a function of pulse repetition frequency(PRF) and duty cycle.A study of the damage mechanism of the device is carried out from the variation analysis of the distribution of the electric field and the current density.The result shows that the accumulation temperature increases with PRF increasing and the threshold for the transistor is about 2 kHz.The response of the peak temperature induced by the injected single pulses indicates that the falling time is much longer than the rising time.Adopting the fitting method,the relationship between the peak temperature and the time during the rising edge and that between the peak temperature and the time during the falling edge are obtained.Moreover,the accumulation temperature decreases with duty cycle increasing for a certain mean power.展开更多
A single-resonant low-threshold type-Iβ-Ba_(2)BO_(4)(BBO) optical parametric oscillator (OPO) with tunable output from 410 nm to 630 nm at 5 k Hz repetition rate is reported.By taking the noncollinear phase matching ...A single-resonant low-threshold type-Iβ-Ba_(2)BO_(4)(BBO) optical parametric oscillator (OPO) with tunable output from 410 nm to 630 nm at 5 k Hz repetition rate is reported.By taking the noncollinear phase matching method,low-threshold OPO operation could be obtained compared with the configuration of collinear phase matching,and the maximum optical–optical conversion efficiency of 11.8%was achieved at 500 nm wavelength when 0.4 m J pump pulse energy was applied.When the noncollinearity angle was preset at 1.6°,4.8°,and 6.3°,a continuously tuning output with a total spectral range of 220 nm was successfully obtained by adjusting the phase matching angle of the BBO crystal.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 60776034)
文摘In the present paper we conduct a theoretical study of the thermal accumulation effect of a typical bipolar transistor caused by high power pulsed microwaves(HPMs),and investigate the thermal accumulation effect as a function of pulse repetition frequency(PRF) and duty cycle.A study of the damage mechanism of the device is carried out from the variation analysis of the distribution of the electric field and the current density.The result shows that the accumulation temperature increases with PRF increasing and the threshold for the transistor is about 2 kHz.The response of the peak temperature induced by the injected single pulses indicates that the falling time is much longer than the rising time.Adopting the fitting method,the relationship between the peak temperature and the time during the rising edge and that between the peak temperature and the time during the falling edge are obtained.Moreover,the accumulation temperature decreases with duty cycle increasing for a certain mean power.
基金This work was supported by the Natural Science Foundation of Shanghai(No.19YF1453600)the Key Task Project in Scientific and Technological Research on Social Development of Shanghai(No.20dz1206502)+2 种基金the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018SDKJ0102)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22000000)the Major Program of the National Natural Science Foundation of China(No.61991453)。
文摘A single-resonant low-threshold type-Iβ-Ba_(2)BO_(4)(BBO) optical parametric oscillator (OPO) with tunable output from 410 nm to 630 nm at 5 k Hz repetition rate is reported.By taking the noncollinear phase matching method,low-threshold OPO operation could be obtained compared with the configuration of collinear phase matching,and the maximum optical–optical conversion efficiency of 11.8%was achieved at 500 nm wavelength when 0.4 m J pump pulse energy was applied.When the noncollinearity angle was preset at 1.6°,4.8°,and 6.3°,a continuously tuning output with a total spectral range of 220 nm was successfully obtained by adjusting the phase matching angle of the BBO crystal.