一种超低电压宽带调谐太赫兹回旋管互作用结构

低电压频率可调太赫兹回旋管在生物医学和波谱学等领域具有重要应用。文章分析了超低电压(<1 kV)下采用传统开放腔互作用电路的330 GHz 回旋管输出功率和频率调谐特性,探讨了超低电压下由于电子相对论效应减弱而导致的回旋管中电子注-波互作用耦合强度降低的问题。在此基础上,针对330 GHz 超低电压回旋管提出了一种改进的互作用电路结构,其下倾式尾端结构有助于增大反向波幅度,提高弱相对论电子注与电磁波之间的耦合强度,从而提高回旋管的输出效率及频率调谐带宽。非线性模拟结果表明,在低至0.3 kV 的超低电压下,采用此种互作用电路结构仍可获得大于1 W 的连续波输出功率及22 GHz 的连续调谐带宽,峰值输出效率大于7%。     

复合周期磁场共轴回旋电子注回旋单腔管的研究

本文在吴坚强(1985)、刘盛纲(1985)工作的基础上,利用线性动力学理论对复合周期磁场共轴回旋电子注回旋单腔管进行了详细的理论分析。推得了注波互作用功率、频偏和起振电流等公式。     

35GHz三次谐波低电压回旋管理论研究

用动力学理论分析了三次谐波复合腔回旋管中的注-波互作用,选取了工作点;建立了突变复合腔回旋管的自洽非线性理论模型,该模型既考虑了电子和高频场的自洽相互作用又考虑了复合腔过渡部分模式的耦合,基于该理论模型,对一只三次谐波35GHz突变结构复合腔回旋管中电子注与H₆₁-H₆₂高频场互作用进行了数值模拟,当电流20A,磁场为0.442T时,互作用效率为24%,输出功率为210kW.     

94GHz渐变复合腔回旋管的设计与实验

根据注-波互作用自洽非线性理论,设计了一种二次谐波回旋管的渐变复合腔结构,并进行了数值模拟;通过采用波纹波导结构和不同的相位重匹配技术进行优化分析,设计了一种94GHz波纹波导模式转换器;根据模拟计算结果研制出了94GHz渐变复合腔二次谐波回旋管。实际测试的结果表明：所研制的回旋管在电子注电压50kV,电流8．8A,工作磁场1．56T时工作频率为94．2GHz,峰值输出功率为115kW,平均输出功率为3kW,效率为26％。     

0.5THz二次谐波同轴回旋管的设计

二次谐波回旋管所需磁场仅为基模的一半,极大地降低了对工作磁场的要求.基于回旋管线性和自洽非线性理论设计了一只0.5 THz回旋管,采用TE56模为工作模式,分析了多项关键参数对注波互作用效率的影响,当其工作电压为49 kV,工作电流为5A,工作磁场为时9.94 T,效率为22.52％,输出功率可达55 kW.     

高次谐波大回旋太赫兹振荡器多模工作特性

设计了一支可工作于4～9次谐波的大回旋太赫兹振荡管,借助于三维粒子模拟,研究了设计的大回旋振荡管注-波互作用机理、高次谐波工作特性、谐波模式间竞争等关键特性。结果表明,通过调节磁场强度,可以在多个相邻谐波处连续激发振荡,实现频率为240 GHz到460 GHz之间的太赫兹波辐射,最大辐射功率为19kW。同时研究了第7、8和9次谐波模式之间的竞争,讨论了实现稳定注-波互作用和高次谐波状态下单模工作的方法。此外,论文还对不同谐波状态下的欧姆损耗功率进行了研究。     

开槽波导3次谐波回旋行波放大管非线性理论与数值模拟

本文讨论了开槽圆柱波导的高频场分布,给出了注波互作用自洽非线性理论,在电子作大回旋运动与考虑速度零散的情况下,采用四阶龙格库塔法,对均匀截面开槽波导３次谐波回旋行波放大管注波互作用进行了数值计算,得出一些重要的互作用规律,为回旋行波放大管的进一步研究打下了基础。     

回旋潘尼管的工作原理

根据发展和结构的不同，叙述了4类潘尼管的工作原理，分别是双对脊波导结构行波潘尼管、圆波导结构和磁 控管型波导结构的回旋潘尼管、人间谐波工作的回旋谐波潘尼管。此外，分析了影响潘尼管工作的几个重要因素。     

W波段二次谐波回旋行波管放大器

采用谐波工作的回旋管互作用磁场比基波磁场降低了1/s,可降低整管磁场设计难度,具有较大的应用前景。通过对W波段二次谐波回旋行波管高频介质加载结构、模式竞争和注波互作用研究,确定了该放大器的工作参数。非线性模拟表明,当应用100 kV,20 A,α=1.2的电子注时,该回旋管可在91 GHz频率处产生465 kW的输出功率和49 dB的增益结果。并且,基于耦合波理论,讨论了一个轴对称半径微扰的TE02~TE01输出模式变换器,效率在95%以上时,其带宽达到4 GHz。     

140GHz/50kW回旋管的研制与测试

回旋管在毫米波与太赫兹频段能够输出高峰值功率和高平均功率,具有重要的应用需求。本文基于回旋管束波互作用理论设计了一只140 GHz回旋管以用于磁约束聚变中电子回旋加热相关元件的测试和老炼,目标是实现最大输出功率不小于50 kW,具备脉冲工作及连续运行能力,且具有一定的频率和功率调节范围以适应测试的需求。根据设计结果开展了该回旋管的研制与测试,在阴极电压-37.2 kV,控制极电压-12.19 kV,阳极电压+11 kV,束流3.4 A,工作磁场约5.3T下获得最大脉冲输出功率56 kW,功率可通过工作电流和磁场进行调节,同样的调节手段还可以使频率获得约80 MHz的调节范围。重点对起振电流、功率曲线和频率曲线等进行了理论计算结果和实验结果的对比,二者获得了良好的一致。由于初步实验中观察到了大于50 kW连续波功率输出时窗片的过温现象,因此降低功率在20.3 kW开展了连续运行实验,结果表明在该功率下回旋管连续运行状态稳定,可以用于后续聚变元件测试和老炼工作的开展。     

High Power,Frequency Tunable,Submillimeter Wave ESR Device Using a Gyrotron as a Radiation Source

ESR device using a submillimeter wave gyrotron as a radiation source and a pulse magnet for high field up to 30 T has been constructed. Our gyrotrons (Gyrotron FU series) were developed as millimeter and submillimeter wave radiation sources and have attractive advantages for ESR spectroscopy, for example, high power and frequency tunability over broad range. The ESR device has been successfully applied to three cases of ESR measurements. In the first case, the temperature dependence of ESR was measured for a typical antiferromagnetic material MnO at the frequency of 301 GHz. In the second case, the dependence of the fine structure constant of the ruby on the magnetic field intensity was measured in the millimeter to submillimeter wave region. In these two cases, the gyrotron was operated by complete cw mode. In the final case, a pulse technique was applied to the ESR, the gyrotron was operated in pulse mode and the pulsed magnetic field was generated in the synchronized phase with the gyrotron operation.     

Investigations of Advanced Coaxial Gyrotrons at IAP RAS

Main results of experimental testing of the 140 GHz/1.5 MW coaxial gyrotron are summarized. High selective properties of the coaxial cavities and a possibility to increase considerably the efficiency of a coaxial gyrotron only by applying independently an appropriate voltage on its electrodes (without any design modification) have been confirmed. Successful uses of the two-potential connection scheme for the frequency step tuning and output power modulation in a coaxial gyrotron has been also demonstrated.     

The Design of the 394.6 Ghz Continuously Tunable Coaxial Gyrotron for DNP Spectroscopy

Results of the numerical investigations of the coaxial-cavity gyrotron with smooth frequency tuning are presented. The tuning is achieved by moving an internal cone-shaped rod along the device axis, which ensures smooth variations in eigenfrequencies of the cavity. The application of an inner conductor with an impedance surface reduces the thermal load on the internal road. The calculation results demonstrate the possibility of tuning the oscillator frequency by 8 GHz for the 394.6 GHz central frequency (within a frequency band of about 2%) with an output power of about several hundreds watts in the CW regime.     

Theoretical analysis of gyrotron amplifier with undulated waveguide

In this paper the interaction between a relativistic electron beam moving in a static magnetic field and a travelling electromagnetic wave is analysed by using the kinetic power theorem. The concept of the electron bunching function is introduced to illustrate the bunching process of beam electrons as a whole. By numerical calculation, the energy exchange process between gyrating electrons and the travelling wave field is obtained in detail. The results of the calculation show that the imaginary part of the axial wave number does not stay constant along the interaction length and that the gain characteristic is non-linear. Based on this analytic method, the maximum output power and efficiency of the gyrotron amplifier with a uniform waveguide are calculated and are found to depend critically on the value of the static magnetic field and the operating frequency. A new type of gyrotron amplifier is suggested here. In this device the gyrating electrons interact with the travelling wave in an undulated waveguide. Its instantaneous bandwidth is somewhat broadened and the optimum value of applied magnetic field is not too critical.     

Linear and Non-Linear Inserts for Genuinely Wideband Continuous Frequency Tunable Coaxial Gyrotron Cavities

We consider two continuous frequency tunable CW coaxial gyrotron oscillators, one 330 GHz with 3 GHz bandwidth and output power 50 – 400 W for scientific applications and one 30 GHz with 0.4 GHz bandwidth and output power 40 – 140 kW for industrial applications. The continuous tuning of both gyrotrons is achieved by moving the linearly tapered inner conductor in the axial direction in combination with the proper adjustment of the operating magnetic field. We consider also a non-linear tapering, which makes it possible to reduce the length of the insert and to improve efficiency of the device.     

Operation of a millimeter-wave harmonic gyrotron

The operation of a millimeter-wave harmonic gyrotron is described in which the interaction is between large-orbit axis-encircling electrons and cylindrical cavity TE_nll modes. Efficiencies up to 15% have been measured for moderate harmonic interactions and multi-kW power levels have been attained at the tenth harmonic of the cyclotron frequency. The concept allows the magnetic field of the gyrotron to be reduced by an order of magnitude, thereby making a submillimeter-wave gyrotron feasible.     

0.42THz频率连续可调同轴回旋管

作为目前工作在太赫兹频段输出功率最大的辐射源之一回旋管的功率可达到数十千瓦. 传统太赫兹回旋管一般为点频工作,难以满足动态核极化核磁共振等多方面技术需要。采用机械调节的方式,实现了带宽为2GHz中心频率为0.42THz二次谐波频率连续可调同轴回旋管,通过非线性理论分析发现,在不改变工作磁场条件下,在调节带宽范围内,可实现大于8kW的功率输出.     

Quasi-optical gyro-peniotron at high cyclotron harmonics

This paper proposes a new kind of device operating at short millimetre wavelength, in which RF radiation generation is based on the interaction of a beam of sub-relativistic gyrating electrons and the RF standing-wave field of a quasi-optical resonator. This device can be called ‘quasi-optical gyro-peniotron’ because it is similar in electron-beam configuration, microwave circuitry and cyclotron resonance properties to the quasi-optical gyrotron and in its operational mechanism to the peniotron. Starting from relativistic equations of motion for the electrons, the calculation formulae are derived. Using computer simulation, a beam-wave interaction efficiency of 43% is obtained for the third cyclotron harmonic at frequency 100 GHz, beam voltage 80 kV and the applied magnetic field 13·3 kG, indicating that this tube will be potentially a high-efficiency high-power source not requiring a superconduction magnet system even within the 150 GHz band.     

Increase of Gyrotron Output Power at High-Order Axial Mode Through an After-Cavity Excitation of the Next Transverse Mode

In the experimental study on the frequency tuning of a double-beam gyrotron, an unexpected abrupt increase of the output power was observed for some magnetic field values corresponding to the excitation of high-order axial modes (HOAM). This effect can be explained through an after-cavity interaction of the spent but bunched electron beam with the neighboring transverse mode which has the same azimuthal but the next (i.e., greater by one) radial index with respect to the operating mode. The calculations show that under certain conditions the cyclotron synchronism between the electron beam and the next radial mode occurs in the extended region of an output cone, while the bunching of the spent electron beam is responsible for the excitation of this mode. The influence of some additional factors such as reflections of both modes from the output window, electron velocity spread, and magnetic field profile was studied numerically. It was shown that reflections, mode transformation, and velocity spread can enhance the effect of an abrupt power increase and reduce the starting current of the operating mode. The discovered after-cavity interaction can be either useful for a power increase at the HOAM operation of the frequency-tunable gyrotron or harmful for high cyclotron harmonic operation due to an expansion of the zone of fundamental cyclotron resonance mode excitation.