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A phase-stabilized superradiant Ka-band oscillator driven by nanosecond voltage pulses with amplitude variations and reduced rise rates
摘要： This paper presents the results of experiments and a numerical simulation of the conditions for phase stabilization (standard deviation < 0.5 rad) of a subgigawatt relativistic superradiant Ka-band backward wave oscillator with the accelerating voltage amplitude varying within 15%. It is shown that phase stabilization can be achieved for the voltage rise rate (dU/dt)max (cid:2) 2 MV/ns by using our recently developed approach. Particular emphasis is given to the cases of substantially lower voltage rise rates at which stabilization of the microwave oscillation phase is also possible. The mode with (dU/dt)max (cid:3) 1 MV/ns is considered for speci?c voltage waveforms that ensure ef?cient kinematic peaking of the beam current. In this case, stabilization of the microwave oscillation phase can be achieved by initiating a voltage prepulse, provided that the accelerating pulse leading edge has a segment of stable rise rate and stable shape.
关键词： superradiant Ka-band oscillator,amplitude variations,reduced rise rates,nanosecond voltage pulses,phase stabilization
更新于2025-09-09 09:28:46
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Stabilizing RbPbBr3 Perovskite Nanocrystals through Cs+ Substitution
摘要： The ABX3-type halide perovskite nanocrystals (NCs) have been a hot topic recently due to their fascinating optoelectronic properties. It has been demonstrated that A-site ion has an impact on the photophysical and chemical properties, such as optical bandgap and chemical stability. The pursuit of halide perovskite materials with diversified A-site species would deepen the understanding on the structure-property relationship of the perovskite family. Herein, we attempt to synthesis the Rb-based perovskite NCs. We discover that the partial substitution of Rb+ by Cs+ helps to stabilize the orthorhombic RbPbBr3 NCs at low temperature, which otherwise can only be obtained at high temperature. The inclusion of Cs+ into RbPbBr3 lattice results in highly photoluminescent Rb1-xCsxPbBr3 NCs. With the increasing amount of Cs+, the bandgap of Rb1-xCsxPbBr3 NCs decreases, leading to the red shift of photoluminescence peak. The Rb1-xCsxPbBr3 NCs (x=0.4) show good stability in ambient condition. This work demonstrates the high structural flexibility and tunability of halide perovskite materials through A-site cation substitution strategy and sheds light on the optimization of perovskite materials for high-performance optoelectronic devices.
关键词： halide perovskite,phase stabilization,cation substitution,RbPbBr3,nanocrystals
更新于2025-09-04 15:30:14