Karst water as the vital supply source is generally suffered from NO3- contamination in intensive agricultural areas worldwide. Identifying sources and transformations key for understanding nitrogen pathways, also effectively controlling diffuse pollution. In this study, chemical variables stable isotopes (δ2H-H2O, δ18O-H2O, δ15N-NO3- δ18O-NO3-) were measured 10 surface (SW) samples 13 groundwater (GW) collected Huixian karst wetland, with application of a Bayesian isotope mixing model...

Propagation and post-acceleration of a pseudospark-sourced electron beam from three-gap pseudospark discharge chamber were studied in recent experiments. The produced an two phases, initial 22 kV, 50 A hollow cathode phase brightness 109−10 Am−2 rad−2 followed by 200 V, conductive (CP) 1011−12 rad−2. aim these experiments was to post accelerate the lower-voltage, higher-current CP using acceleration unit driven 40 125 ns voltage pulse cable Blumlein. realized attaching downstream side anode...

Suppression of the transverse-electromagnetic (TEM) mode leakage is crucial in design a triaxial klystron amplifier with high gain, because small microwave from buncher or output cavity could overwhelm input signal low power. In this paper, specially designed reflector proposed to suppress TEM leakage, whose axial electric field approximately zero at beam radial position. Theoretical analysis indicates that introduces little influence on normal modulation while keeping reflection...

Miniaturization and frequency tunability have become two important development directions of high-power microwave technology. The wideband system based on gyromagnetic nonlinear transmission line (GNLTL) has been proven to the potential produce smaller physical size lighter weight. GNLTL is a special source whose output can be tuned online by changing biasing magnetic field. working mechanism related damping precession moments, parameters material effects microwaves. However, details these...

High-frequency microwave generation based on PCSS devices requires the fastest possible response speed. In this study, we successfully demonstrated controlled donor level doping in 4H-SiC to reduce carrier recombination lifetime and enhance high-frequency generation. PCSSs with three different of nitrogen concentrations were manufactured compared. By femtosecond transient absorption spectroscopy (fs-TAS), observed that doped lower exhibited significantly shorter faster speed, ranging from...

Magnetic pulse compressors, based on magnetic switches, are considered as competitive candidates for high-voltage generation. It is generally believed that the lack of operating-parameter tunability these devices currently one crucial factors limiting their applications. In this paper, an adjustable high-power compressor, which deemed key component a power supply system, investigated theoretically and experimentally. Dominant parameters including compression ratio, saturation time, peak...

The triaxial klystron amplifier is an efficient high power relativistic operating at frequencies due to its coaxial structure with large radius. However, the structures result in coupling problems among cavities as TEM mode not cut-off tube. Therefore, suppression of leakage, especially leakage from buncher cavity input cavity, crucial design a amplifier. In this paper, non-uniform three-gap proposed suppress leakage. cold analysis shows that can significantly generation compared uniform...

The wideband High-Power Microwave (HPM) sources, which combine the advantages of narrowband and ultrawideband have drawn much attention. As a kind source, gyromagnetic nonlinear transmission lines (GNLTLs) can directly modulate incident pulses into radio frequency without relying on interaction between e-beam microwaves. Due to special working mechanism precession, center GNLTL also be adjusted in certain range. Based classical magnetism simplified model GNLTL, this paper semi-quantitatively...

The gyromagnetic nonlinear transmission line (GNLTL) is a compact and solid-state high-power microwave source, which can be treated as special coaxial partially filled with the ferrite material. Due to complex interaction process of electromagnetic fields dynamic damped precessional motion magnetization vector in ferrite, it great challenge theoretically predict output GNLTL. Here, we present novel field-line coupling simulation method waveform GNLTL by simultaneously solving coupled system...

The destructive testing for reliability analysis at high-power microwave (HPM) in the GaAs/InGaP hetero-junction bipolar transistor (HBT) has been rarely investigated although it a significant impact on their performance and against HPM. This paper employs experimental measurements to study HPM damage process. We first establish experiment platform injecting HBT which P1dB output power of +15.5 dBm acquire threshold. It is found that with increasing input power, waveforms are gradually...

The expansion of cathode plasma in magnetically insulated coaxial diode (MICD) is investigated theory and particle-in-cell (PIC) simulation. temperature density the are about several eV 1013–1016 cm−3, respectively, its velocity level few cm/μs. Through hydrodynamic analysis, expressions velocities axial radial directions obtained. characteristics have been simulated through scaled-down PIC models. Simulation results indicate that dominated by ratio other than static electric field. field...

The power capacity of a photoconductive semiconductor switch with the planar electrode is limited by surface breakdown voltage. In this work, an efficient thinned 4H-SiC PCSS backward-triggered structure was fabricated. Comparison simulations on photocurrent density and electric field showed that distribution photogenerated carriers homogenized, maximum declined. By thinning polishing, (PCSS) devices thicknesses 50 500 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML"...

The feasibility of employing an annular beam instead a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated theory and simulation. Small-signal analysis indicates that optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, beam-loaded quality factor beams are all larger than corresponding parameters at same voltage current. An RKA with almost geometric compared particle-in-cell Output microwave power 100 MW, gain 50...

The mechanism and realization of a relativistic backward-wave oscillator (RBWO) with frequency-selectable across X- Ku-bands are presented. Both the transverse longitudinal mode selections contribute to different bands. selection is achieved using property “surface wave” slow-wave structures excite coaxial TM01 (Ku-band) or hollow (X-band) without exciting higher TM modes. by introduction extractor, which contributes compact structure restraints competitions. In simulation, Ku-band microwave...

Abstract A high-efficiency C-band coaxial transit time oscillator with a dual-cavity extractor under low-magnetic fields is designed and studied through small-signal theory particle-in-cell simulation. Small-signal analysis indicates that superior to single-cavity in terms of the beam-coupling coefficient, resonant frequency, external quality factor, which are good for high efficiency. Typical simulation results proposed device show an output power 1.73 GW frequency 6.37 GHz can be obtained...

Unlike planar diodes, separate research of the axial and radial plasma expansion velocities is difficult for magnetically insulated coaxial diodes. Time-resolved electrical diagnostic which based on voltage-ampere characteristics has been employed to study temporal evolution cathode in a long pulsed diode. Different from diode with “U” shaped profile velocity evolution, trend proved be “V” profile. Apart suppression velocity, strong magnetic field also conducive slowing down velocity....

A novel specification driven and constraints solving based method to automatically generate test programs from simple complex ones for advanced microprocessors is presented in this paper. Our microprocessor architectural automatic program generator (MA/sup 2/TG) can produce not only random but also a sequence of instructions specific constraint by specifying user file. The proposed methodology makes three important contributions. First, it simplifies the architecture modeling eases adoption...

The influences of the eigenfrequency and intrinsic quality factor a cavity on phase shift in relativistic klystron amplifier (RKA) are investigated. An analytical expression is derived to describe gap voltage cavity. theoretical simulation results indicate that buncher can significantly affect output microwave RKA. In contrast, RKA small. effectively estimate difference among different RKAs resulting from machining assemblage inconformity experiment. It suggested differences eigenfrequencies...

摘 要 森林凋落物动态是森林生态系统过程中的重要组成部分, 探索森林凋落物动态特征与微气候间的关系, 对深入了解 生态系统变化过程运行机理具有重要意义。该研究以浙江普陀山岛典型森林类型枫香(Liquidambar formosana)林、天竺桂 (Cinnamomum japonicum)+红楠(Machilus thunbergii)林、马尾松(Pinus massoniana)林、青冈(Cyclobalanopsis glauca)林、台湾 蚊母树(Distylium gracile)林为研究对象, 探究森林凋落量与微气候的关系。结果表明: 1)森林年凋落量介于3.45-5.36t•hm -2 •a -1 , 年凋落量各组分比例表现出不同的组成特征, 森林类型与森林月凋落量无关。2)森林月凋落量动态模式主要呈双 峰型和三峰型, 凋落峰值和风速峰值趋势相一致, 主要集中在台风干扰较大的4

Dispersed karst water is an important supply source, or even the only for some districts and counties in Chongqing City. It particularly necessary to understand distribution characteristics of metal elements health risks exposed. In this study, scattered southeastern part was taken as main research object, concentrations Al, Cu, Pb, Zn, Cr, Cd, Ni, Mn, As, Hg 42 groups spring samples were determined. The spatial with a high detection rate revealed using ordinary kriging interpolation method,...