从微波理论出发,经过数学变换,建立了群时延与速调管输出腔间隙自阻抗实部的数值关系.用此新方法与传统方法测试了工程上成熟的某速调管的双间隙输出腔.然后,讨论了用群时延来估算间隙阻抗的可行性与局限性,并给出了群时延法与传统方法之间的误差分析.由于该方法的提出基于基本的理论,因此不受具体频段的限制,可应用于微波、毫米波以及亚毫米波等波段.

A new strong coupling multi-gap output structure has been developed as the output cavity of Ka band sheet beam klystrons. This structure has a better output coupling characteristics and better shape of electric field. Moreover, when the drift tube of the output cavity is cut-off in the operating frequency, an ideal field shape can be obtained as to support more efficient beam-wave interaction. An analysis of the distribution of the surface current supports the design theoretically. A stable output power curve can be observed at the center frequency by using particle-in-cell simulations, where the interaction efficiency is more than 50% and the 3dB bandwidth is about 75MHz. Key words; sheet-beam; strong coupling; multi-gap output cavity

A novel method was developed to balance the distribution of the longitudinal electric field (in the beam propagating direction) in the single-port input cavity's gap of the X-band sheet beam klystron. The original work is that a loaded waveguide is installed at the opposite side of the input cavity, so that the field can be adjusted within a certain range to achieve a uniform distribution. The newly-developed technique simplifies the driving unit, and solves the problem of the input signal asynchronism of the double-port input. The structure was optimized by means of a simulation with software package CST-Microwave Studio. The feasibility was verified with the lab-built cold test setup. The tested results show that the loaded waveguide is capable of easily adjusting the field distribution. In addition, the depth of the tuning nail and the dimension of the coupling aperture were found to strongly affect the field distribution. The experimental data agree fairly well with the simulated results.

In this paper, the dumbbell resonant cavity frequency tuning method and beam wave interaction system of W band sheet beam Klystron (WSBK) has been studied. Under the designed value of beam voltage 75kV, beam current 3.8A, and beam size of 10*0.5 mm 2 , the structures and high frequency parameters of single gap and multi-gap cavities are tested and discussed to achieve the higher output power in detail. With the tuning system proposed, the bandwidth of 100MHz can be obtained. Then, the output power is calculated by both 2-dimensional software SBK2D and the 3D PIC program, and the results agree very well.

The dumb bell resonant cavity characteristics for W-band sheet beam klystron (SBK) are analyzed with one-, three-, and five-gap coupled cavity models by three dimensional high frequency simulation software(CST-MSW). The dependence of the cold parameters on the configurations of the cavity was analyzed. For the particle in cell (PLC) simulation analysis, the optimized cavity frequency combination of eight-cavity WSBK circuit was obtained using 2-D software SBK2D, which runs with high speed, thereby allowing an efficient investigation of input parameters. To unify the electronic-beam wave interaction system's hot parameter design, the calculated results are examined by PIC simulation (MAGIC-3D), and show good agreement with CST, thereby confirming the design method mentioned above. These results provide key parameters and a good foundation for developing higher performance on RF structure of sheet beam klystron in the future.

In this paper, a 2.5-dimensional macro-particle model is proposed for a nonaxisymmetrical and large width-height ratio sheet beam klystron (SBK) and a corresponding beam-wave interaction program is developed. An X-band 100-MW SBK is simulated for testing the computing capability of the program. The results are in good agreement with those from 3D PIC software, and the computation time can greatly be reduced, which is useful for the initial design and the optimization of the SBK beam-wave interaction structure.

The sheet beam klystron (SBK) is characterized by a large rectangular drift tube, which allows the use of a high current, low voltage beam, resulting in a low beam current density, and hence high efficiency and the possibility of Periodic Permanent Magnet (PPM) focusing. Our research group has designed a 5-Cavity X-Band SBK recently. In this paper, we discusses the general design of this X-Band SBK and presents the transfer characteristic of it predicted by a large signal code we developed.

The sheet beam klystron (SBK) is characterized by a large rectangular drift tube, which allows the use of a high current, low voltage beam, resulting in a low beam current density, and hence high efficiency and the possibility of Periodic Permanent Magnet (PPM) focusing. Our research group has designed a 5-Cavity X-Band SBK recently. In this paper, we discusses the general design of this X-Band SBK and presents the transfer characteristic of it predicted by a large signal code we developed.

带状电子注具有非轴对称性和大宽高比的特性，非常适合应用于高功率微波与毫米波真空电子器件电子注形成。该文针对带状电子注的这种特性，建立了2维窄带宏粒子模型，编写了静电磁约束下带状电子注传输过程的分析计算程序，讨论了无外加高频场时带状电子注在均匀磁场和周期会切磁场聚焦情况下的传输过程，数值计算结果与单粒子模型及3维PIC软件模拟结果进行了比较，结果表明，该文编写程序的计算结果与3维PIC软件的有很好的一致性，且计算速率有大幅度提升。

A novel technique has been successfully developed,to calculate the external quality factor of the klystron output cavity with double coupling apertures,by means of the curve of the scattering parameter S21.Firstly,this kind of output cavity for MBK-E3736(Toshiba) was modeled and simulated with the software CST-MWS.And then the external quality factor of the output cavity was calculated by the technique,and the results were consistent with the literature.Furthermore,the new technique was used in evaluating the external quality factor of this type of output cavity for the S-band klystron prototype fabricated in IECAS.The calculated results agreed well with those obtained in the cold test.

The sheet beam klystron is a new kind of microwave vacuum device,which uses a high aspect ratio,thin rectangular beam to reduce space charge effects,the special rf structure to increase power capability and beam-wave interaction efficiency.By means of PIC simulation software,a 3D design platform of beam-wave interaction system was established,and applied to design and simulate the beam-wave interaction system of a W-band sheet beam klystron.Detailed parameters for the primary design were presented.The PIC simulation results indicate that output power of larger than 573 kW and gain of 27.8 dB can be obtained under the condition of 140 kV voltage,15 A current.The efficiency exceeds 27.3%.

The development of millimeter wave sheet beam devices recently indicated that this type of device have much more advantages and applications.However,it also has several technical difficulties that must be solved.The advantages,state of arts and its trend,and difficulties of the sheet beam devices are analyzed in detail.The electron optics system for the W-band sheet beam klystron(WSBK) developed in IECAS recently are emphasized.We have built the sheet electron beam tube using Wiggler focusing structure with the beam aspect ratio of 25∶1.With beam voltage of 60 kV,and beam current of 2.6 A,the transmission rate of the sheet beam tube manufactured is more than 55% with the drift length 50 mm.Furthermore,the much more research works of techniques and experiments for the millimeter wave sheet beam devices are being performed in IECAS thoroughly.

A coaxial output cavity with reentrant ring and short circuit pole for multiple-beam klystron (MBK) is presented, which can increase the frequency interval between operating mode TM310 and neighboring modes to more than 1.0 GHz in X-band, diminish the external Q-factor from 535.4 to 202.2, and make the field distribution of TM310 mode symmetrical enough. The simulation results are obtained by CST-MWS.

At millimeter wavelengths, there is a growing need for a small size and weight, high average power RF source. The sheet beam klystron (SBK) is ideally suited to many of these needs. The SBK is characterized by a large rectangular drift tube, which allows the use of a high current, low voltage beam, resulting in a low beam current density, and hence high efficiency and the possibility of PPM focusing.

In the late year, a sheet beam electron gun was designed and tested as the first step for the planned high power X-band sheet beam klystron. The primary design parameters of electron gun are as follows: beam voltage 300 kV, beam current 330 A, then the beam perveance is about 2.0 μp. According to the electric structure from simulation, a prototype gun is built and tested. The preliminary experimental results in the low voltage region have shown that the sheet beam gun is successful until now.

Simulations of the electron optics system and beam wave interaction system for W-band Sheet Beam Klystron (SBK) were done and a beam stick was fabricated. Under the beam voltage of 60 kV and current of 2.6 A, the beam transmission has achieved 99%. In this paper the results of both simulation and experiment are described.

In this paper, the design of input and output cavity for X-band sheet beam klystron was presented. The fabrication and cold test of a barbell cavity were conducted, and the cavity characteristics were predicted by both CST simulation and measurement.

The beam-wave interaction system with five three-cell,extended interaction cavities in the X-band sheet beam klystron,working in π mode,was simulated with two commercial available software packages of 3-dimensional particle-in-cell(PIC)and Computer Simulation Technology(CST).In the simulation,realistic conditions,including the non-axial symmetry structure of the sheet beam,moving charge-induced electric field,and space charges,were considered.The preliminary,simulated results show that for a 415kV,250A sheet beam,the sheet beam klystron is capable of generating an output power higher than 29.6 MW with a gain of 34.3 dB and a maximum efficiency of 29.9%at a frequency of 11.425GHz.The design considerations and potential applications of the sheet beam klystron,a novel microwave vacuum device using a high aspect ratio,thin rectangular beam to reduce space charge,were also tentatively discussed.

An L-band 10 MW peak power, 150 kW average power multi-beam klystron (MBK) is studied. High quality multiple paracial electron optics system axis are achieved in a uniform, multi-lens magnetic field focusing system. The non-linear calculation of beam-wave interaction is carried for the L-band MBK with six electron beams and six coaxial cavities including a second harmonic cavity. The results show that the multi-beam klystron can produce an output peak power of more than 10 MW, an efficiency of more than 65% and a gain of more than 45 dB with a beam voltage of 115 kV and a beam current of 132 A.

The sheet beam klystron is a new kind of microwave vacuum device,which uses a high aspect ratio,thin rectangular beam to reduce space charge effects,the special RF structure to increase power capability and beam-wave interaction efficiency.In this paper,the one-cell and three-cell cavities of X-band sheet beam klystron were studied.Analysis and calculations of frequency characteristic have been done by using three-dimensional electromagnetic code,and the unique characteristics are analyzed and discussed in this paper.