Flicker noise in millimeter-wave backward wave oscillators

Conclusions Thus the proposed experimental — analytical technique has demonstrated its usefulness in investigation of the nonstationary noise in millimeter wave oscillators as well as allows one to get the oscillator output modelling spectrum comparable with the real one to distinguish the factors which take part in the oscillator signal spectrum forming. This technique can be successfully applied to the oscillator spectrum modelling atf<10H z off the carrier frequency domain.     

Scattering in backward wave oscillators from turbulent electric fields

Relativistic electrons resonating in microwave-emitting slow-wave structures can scatter from background turbulence. We calculate the expected scattering rate from strong fields characterized by a single mean correlation length. Comparison with recent data from a backward wave oscillator, using the measured magnitude of E-fields, shows agreement with the magnitude of outward scattering. The implied correlation lengths then explain why gas ionization in the same oscillator does not proceed exponentially, as earlier work showed was expected but not observed. Plasma electrons scattered over the correlation length cannot gain the necessary energy to ionize many gas atoms. These results suggest that inadvertently produced plasmas may have a quick, decisive effect on beam geometry, ending microwave emission prematurely.     

相对论返波管超辐射产生与辐射的数值模拟研究

本文研究了相对论返波管产生X波段超辐射问题,产生中心频率为9.25 GHz的电磁脉冲,并在相对论返波管的输出端直接接入VLASOV辐射天线.提出将粒子模拟软件UNIPIC与自行研制的天线辐射模块相结合,实现超辐射现象微波的产生以及辐射的全过程模拟,并研究了输出功率随注入波脉冲以及填充稀有气体气压的变化.模拟结果表明,器件的峰值功率可以达到3.68 GW,瞬时效率超过100%,VLASOV天线在斜切角为20?时,天线的增益达到15.5 dB,在1 km处的功率密度可达到0.728 W/cm2.     

Characteristics of InSb mixers and backward wave oscillators in a submm heterodyne receiver

In this paper some aspects of two of the most important components of a previously described submm heterodyne are discussed: the InSb mexer and the backward wave oscillator. The (known) properties of the InSb mixer and our method of fabrication will be briefly discussed. The aspect of matching this mixer to the waveguide is treated more extensively both in theory and practice. Finally the performance of InSb as a mixer at higher frequencies is briefly considered. Some properties of the backward wave oscillator which are of special relevance when using it in combination with an InSb mixer, have been measured and they are discussed in the last section.     

Submillimeter wave detector workshop

A brief report on the results of a workshop concerning submillimeter wave detection held September 34, 1985.     

Millimeter wave self-mixing oscillators

Self-oscillating mixers in both dielectric and waveguide cavities have veen investigated in the 60 GHz frequency range. The deveces consist of negative resistance diodes of GaAs and InP material coupled to waveguide cavities or high resistivity dielectric cavities such as silicon or Al₂O₃. Experimental measurements show that these devices have a sensitivity in the order of –80 dBm with the intermediate frequency at 60 MHz and an IF bandwidth of 120 MHz. Applications are suggested based on minimum detectable signal and RF power capabilities for systems requiring small size and low cost.     

0.14 THz返波管器件

对有限引导磁场环形电子束的色散曲线作了理论推导,并利用该色散关系数值计算了正弦慢波结构的色散曲线。采用KARAT模拟程序对0.14 THz返波管进行了粒子模拟,并在RADAN303脉冲源上开展了初步的实验研究,实验获得频率大于0.14 THz、脉冲宽度1~2 ns和辐射功率大于100 kW的太赫兹波输出。     

Dynamics of backward electron beams in multiwave Cherenkov oscillators

The dynamics of electrons in a multiwave Cherenkov oscillator are analyzed, based on the results from numerical modeling. It is shown that a flux of charged particles moving contrary to the initial beam is formed at the moment of generating a radiation pulse in an oscillator. The basic parameters of this backward beam are given.     

0.14 THz返波管器件

对有限引导磁场环形电子束的色散曲线作了理论推导,并利用该色散关系数值计算了正弦慢波结构的色散曲线。采用KARAT模拟程序对0.14 THz返波管进行了粒子模拟,并在RADAN303脉冲源上开展了初步的实验研究,实验获得频率大于0.14 THz、脉冲宽度1～2 ns和辐射功率大于100 kW的太赫兹波输出。     

正交场返波管太赫兹源慢波系统

为解决正交场返波管太赫兹源慢波结构的设计问题,研究了开放式单排矩形梳齿慢波结构的色散及耦合阻抗特性并给出了设计思路及结果。利用单模近似法和数值计算得到了各几何参数对慢波结构性能的影响。结果表明:慢波周期长度可相对独立地优化耦合阻抗;设计慢波结构时可根据工作频率、加工工艺和电子枪性能确定其余三个几何参数,主要是对慢波周期长度进行调节。进一步的数值计算给出了梳齿间距在0.010~0.025 mm范围内、工作频率在300~420 GHz范围内的开放式矩形梳齿慢波结构的具体尺寸。利用粒子模拟软件对一个设计结果进行了仿真,得到的工作频率验证了冷腔分析的结果。     

正交场返波管太赫兹源慢波系统

为解决正交场返波管太赫兹源慢波结构的设计问题,研究了开放式单排矩形梳齿慢波结构的色散及耦合阻抗特性并给出了设计思路及结果。利用单模近似法和数值计算得到了各几何参数对慢波结构性能的影响。结果表明：慢波周期长度可相对独立地优化耦合阻抗;设计慢波结构时可根据工作频率、加工工艺和电子枪性能确定其余三个几何参数,主要是对慢波周期长度进行调节。进一步的数值计算给出了梳齿间距在0.010~0.025 mm 范围内、工作频率在300~420 GHz 范围内的开放式矩形梳齿慢波结构的具体尺寸。利用粒子模拟软件对一个设计结果进行了仿真,得到的工作频率验证了冷腔分析的结果。     

New NRD guide MM wave oscillators

A new millimenter-wave Gunn oscillator is described. The present structure makes use of NRD guide and metal resonant cap. The field expressions and the design considerations of NRD guide are discussed. Some experimental results of 8mm and 6mm band oscillators show that the new Gunn oscillator has a future as an integrated millimeter-wave source.This work was supported by National Natural Science Foundation of China     

相对论返波管振荡器齿状阴极

研究了一种齿状阴极的电子束产生传输过程以及对相对论返波管振荡器产生高功率微波的影响。基于SINUS881加速器,利用束流轰击金属靶观测齿状阴极产生电子束在不同轴向位置上的角向分布,并开展了基于环形阴极和齿状阴极的X波段相对论返波管振荡器的实验研究。对不同齿数及尺寸对电子束流特性、器件输出微波功率和脉冲宽度的影响进行了分析。实验结果表明：当阴极的齿数增加到一定数量时,电子束的横向运动使得电子束在径向逐渐趋于分布均匀;与均匀环形阴极的打靶结果近似,此时,电子束对于相对论返波管振荡器产生微波的功率和脉宽影响不大。     

Theoretical investigation of a backward wave oscillator

From the linear Vlasov equation, the theoretical investigation on relativistic backward wave oscillator is performed. The relationship between the microwave power and the guiding magnetic field, which accords with the results of the particle simulation and experiments, is deduced.     

Explosive instability in a backward wave oscillator

A plasma filled backward wave oscillator supports Trivelpiece-Gould (TG) and TM modes. The former can be driven unstable by a relativistic electron beam via Cerenkov interaction or by the plasma return current as two stream instability. This unstable TG mode can parametrically couple to a TM mode via a negative energy beam mode giving rise to an explosive instability     

捷变频相对论返波管振荡器设计

基于低磁场返波管振荡器的工作原理,设计了一个捷变频相对论返波管振荡器,该器件由两段对电子束参数要求基本一致的慢波结构串接而成,通过调节引导磁场强度实现器件频率的调节,使其分别工作于C波段和X波段。在电子能量和束流分别为670 keV和8 kA的条件下,当引导磁场强度为0.5 T时,采用2.5维PIC程序模拟得到频率为6.28 GHz、功率为1.0 GW的微波输出;而当引导磁场强度为0.8 T时,得到频率为9.25 GHz、功率为0.75 GW的微波输出。     

Submillimeter wave generation by second harmonic operation of tunable gyrotrons

The gyrotrons developed at the University of Sydney are tunable sources of millimetre and submillimetre radiation. The generation of submillimetre wavelengths requires operation at the second harmonic of the electron cyclotron frequency, or higher. Our latest gyrotron, GYROTRON IVA, has successfully achieved second harmonic operation and obtained frequencies up to 590 GHz (=0.51 mm). The experimental results and conditions for second harmonic operation will be presented. The design of a new gyrotron, GYROTRON V, which is especially optimised for the second harmonic, will also be included.     

Theoretical investigation of a backward wave oscillator

From the linear Vlasov equation,the theoretical investigation on relativistic backward wave osciUator is performed.The relationship between the microwave power and the guiding magnetic field,which accords with the results of the particle simulation and experiments,is deduced.     

相对论返波管振荡器齿状阴极

研究了一种齿状阴极的电子束产生传输过程以及对相对论返波管振荡器产生高功率微波的影响。基于SINUS881加速器,利用束流轰击金属靶观测齿状阴极产生电子束在不同轴向位置上的角向分布,并开展了基于环形阴极和齿状阴极的X波段相对论返波管振荡器的实验研究。对不同齿数及尺寸对电子束流特性、器件输出微波功率和脉冲宽度的影响进行了分析。实验结果表明:当阴极的齿数增加到一定数量时,电子束的横向运动使得电子束在径向逐渐趋于分布均匀;与均匀环形阴极的打靶结果近似,此时,电子束对于相对论返波管振荡器产生微波的功率和脉宽影响不大。