Relativistic three-centimeter backward-wave tube with 3 GW pulse power

In this paper, we present the results of investigations of a uniform three-centimeter relativistic backward-wave tube (BWT) with circular waveguide operating mode E₀₁ with pulse power 3 GW and efficiency about 20%. We have obtained a dependence of the radiation pulse duration on the generated power. We discuss the problems involved in shortening the duration of the microwave pulses in oscillators with high microwave field intensity on the surface of the slow-wave structure. Institute of High-Current Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 84–88, December, 1996.     

Relativistic backward-wave tube with mechanically tunable generation frequency over a 14% range

A tunable-frequency low-magnetic-field relativistic microwave oscillator is realized experimentally based on a relativistic backward-wave tube with a modulating resonance reflector. The generated frequency is tuned mechanically by moving the oscillator slow-wave structure relative to the reflector. At fixed parameters of the corrugations and of the electron bunch, a frequency tuning range of about 14% measured between −3-dB (relative to the maximum peak generated microwave power) points is realized. The maximum pulse power of 3.4 ± 0.7 GW was obtained at a carrier frequency of 3.65 GHz in a magnetic field of 0.44 T.     

Relativistic backward-wave tube with nonuniform phase velocity of the synchronous harmonic

We have investigated the possibility of increasing the efficiency of a moderately relativistic backward-wave tube (BWT) by longitudinal modification of the phase velocity profile of the synchronous (−1) spatial harmonic. We have shown theoretically that the efficiency of oscillators with a nonuniform electrodynamic system may reach 60% in the approximation of a near zero space-charge field. We have found that the use of nonuniform periodic structures leads to reduction of the critical value of the space-charge field, and also impairment of the adaptive properties of the device. In our experiments, we have realized backward-wave oscillators (BWO) with 40% efficiency and microwave radiation power of 500 MW. Institute of High-Current Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 56–61, December, 1996.     

Regulation of the output energy of a backward-wave linear accelerator by the duration of the rf power pulse

The problems of regulating the output energy of the accelerated beam of a backward-wave linear proton accelerator over a wide range without altering the beam intensity are investigated. The proton energy is regulated by adjusting the duration of the rf power pulse delivered to the accelerator and by regulating the delay time between the instant of injection and the instant at which the leading edge of the rf pulse arrives at the output end of the accelerator. The method is tested on the interdigital-type accelerating section of length 1.25 m of a linear proton accelerator. It is shown experimentally that the electron beam energy at the accelerator output can be varied approximately threefold without any appreciable sacrifice of the beam intensity by varying the duration of the rf pulse in the given accelerator section. Zh. Tekh. Fiz. 68, 135–137 (May 1998)     

同轴引出相对论返波管

 提出一种新型相对论返波管 同轴引出相对论返波管结构。首先,利用KARAT软件对这种结构进行了2.5维全电磁粒子数值模拟,经过参数调整,输出的微波脉冲功率为2.0GW,微波频率为9.28 GHz,转换效率达45%。并在模拟中对电子束与电磁波的作用过程进行了跟踪和分析;然后利用SUPERFISH软件对此结构中的场分布进行了计算,结合PIC模拟结果,初步证明了由于内导体的引入改变了返波管末端的反射,有利于电子束与电磁波的能量交换。     

同轴引出相对论返波管

提出一种新型相对论返波管 同轴引出相对论返波管结构。首先,利用KARAT软件对这种结构进行了2.5维全电磁粒子数值模拟,经过参数调整,输出的微波脉冲功率为2.0GW,微波频率为9.28 GHz,转换效率达45%。并在模拟中对电子束与电磁波的作用过程进行了跟踪和分析;然后利用SUPERFISH软件对此结构中的场分布进行了计算,结合PIC模拟结果,初步证明了由于内导体的引入改变了返波管末端的反射,有利于电子束与电磁波的能量交换。     

Relativistic Cherenkov plasma maser of microsecond pulse duration

Experiments with a Cherenkov plasma maser (CPM) driven by a high-current relativistic electron beam of microsecond pulse duration are described. The results obtained show that the principle of operation of the CPM makes it possible to avoid the problem of microwave pulse shortening, which is inherent to vacuum devices of relativistic high-current microwave electronics. A 800-ns microwave pulse with an energy of 21 J was obtained at a peak power level of 40 MW (the efficiency being 4%) in a broad (~100%) frequency band     

Chaotic generation in a megawatt backward-wave tube

Experimental and theoretical studies on the self-modulation mode of generation in a high-power BWT with the electrodynamic system representing a slightly corrugated waveguide are presented. The BWT is fed by an electron beam with the energy 150 keV and the current 150 A. The system operates at the E ₀₁ mode with the mean frequency 8.7 GHz. Dynamic chaos is obtained by a three-fold increase in the length of the interaction space in comparison with the prototype exhibiting stationary generation. The stationary generation was changed to periodic sinusoidal self-modulation and then to chaotic self-modulation as the current increases from 6 to 60 A. The generation mode is simplified when the current ranges from 70 to 90 A and becomes complicated again for the current exceeding 100 A. Experimental observations are in good agreement with the results of simulation predicting a certain simplification of the self-modulation mode at the currents 70–90 A owing to the effect of high-frequency space charge. Under the conditions of chaotic generation, the mean power was as high as 2 MW at the relative spectral width of the signal 4% and the total duration of the microwave pulse 10 μs.     

Relativistic string in a pulse

I study a relativistic open string coupling through its endpoints to a plane wave with arbitrary temporal profile. The string’s transverse oscillations respond linearly to the external field. This makes it possible to solve the classical equations, and to calculate the quantum-mechanical S-matrix in closed form. I analyze the dynamics of the string as the characteristic frequency and duration of the pulse are continuously varied. I derive, in particular, the multipole expansion in the adiabatic limit of very long wavelengths, and discuss also more violent phenomena such as shock waves, cusps, and null brane intersections. Apart from their relevance to the study of time-dependence in superstring theory, these results could have other applications, such as the teleportation of gravitational wave bursts by cosmic strings.     

Transforming pulse tube radiation by means of fluorescent solutions

The data presented below indicate that under certain conditions solutions of organic luminophors transform the radiation of pulse tubes in such a way that the intensity of radiation increases more than twofold in the 550 and 580 nm spectral ranges and 1. 5-fold in the 630 nm range.The authors are grateful to V. V. Lelinskii for supervising the present study.     

螺旋线行波管返波自激振荡的研究

 在2维小信号模型的基础上，分析了均匀和周期永久聚焦磁场对抑制返波自激振荡的影响。研究结果表明：改变聚焦磁场的幅值或周期来增加起振长度是可能的， 而且不会改变基波的互作用条件。与此同时，对起振长度、初始非同步速度参量随皮尔斯增益参量、空间电荷参量、损耗参量等的变化，以及在超宽带行波管中当存在两个或多个角向非对称空间谐波时,起振长度、初始非同步速度参量随周期永久聚焦磁场的变化进行了研究。优化设计聚焦磁场、电子注和螺旋线慢波系统的参量可以对螺旋线行波管的稳定性分析提供必要的依据。     

螺旋线行波管返波自激振荡的研究

在2维小信号模型的基础上,分析了均匀和周期永久聚焦磁场对抑制返波自激振荡的影响。研究结果表明：改变聚焦磁场的幅值或周期来增加起振长度是可能的, 而且不会改变基波的互作用条件。与此同时,对起振长度、初始非同步速度参量随皮尔斯增益参量、空间电荷参量、损耗参量等的变化,以及在超宽带行波管中当存在两个或多个角向非对称空间谐波时,起振长度、初始非同步速度参量随周期永久聚焦磁场的变化进行了研究。优化设计聚焦磁场、电子注和螺旋线慢波系统的参量可以对螺旋线行波管的稳定性分析提供必要的依据。     

Electro-optically Q-switched lasers with polarization output coupling and their pulse control

We present a design of E/O Q-switched laser with polarization output coupling. Based on laser rate equations, we analyzed pulse control of this type of laser. A model of laser pulse generating is set up. The relationship between pulse energy and high voltage values is given in this model. The experiments have been carried out. The result fits the theoretical model well.     

Theoretical and experimental research on the pulse duration of excimer laser output

The effects of discharge stability and cavity buid-up time of pulse laser on thepulse duration of excimer laser are investigated theoretically.The characteristics of the ex-cimer laser pulse duration can be explained by these theoretical analysis.     

Synchronization of oscillations in a backward-wave tube: Theory and experiment

Synchronization of oscillations in an electron-wave system with a backward electromagnetic wave is studied theoretically and experimentally. The characteristics of nonautonomous oscillations in the backwardwave tube are analyzed with allowance for the space charge and physical processes accompanying the transition of the distributed autonomous system to the synchronization regime. Theoretical results are compared with experimental data.     

Relativistic X-band BWO with 3-GW output power

Results from a study of a relativistic X-band backward-wave oscillator (RBWO) with 3-GW output microwave power are presented. The RBWO was driven by the high-current electron accelerator SINUS-7. The dependence of radiated microwave pulse duration on microwave power was obtained. Pulse shortening occurring at the higher power levels is probably attributable to explosive electron emission from the slow wave structure (SWS). An increase in the cross section of the electrodynamic structure seems to be a way to increase the microwave pulse duration. Experimental results from a moderately oversized X-band RBWO using a resonance reflector are described. This tube can be operated with a low external magnetic field     

Relativistic twistron based on backward-wave oscillator with modulating reflector and an efficiency of 56%

Technical Physics - Using numerical simulation, the operating mode of a relativistic Cherenkov microwave generator of the twistronic type has been demonstrated. The generator includes an...