Yaogen Ding

S-band multibeam klystron with bandwidth of 10%

Summary form only given. The multi-beam klystron (MBK) is a type of compact high power microwave vacuum device with low beam voltage, high efficiency, high gain and wide bandwidth. An S-band MBK, designated the KS4116, with a bandwidth of 10%, developed by IECAS, is introduced in this paper. The main design specifications of the KS4116 are as follows: operating frequency range, S band; peak power, 120-150 kW; average power, 3.6-4.5 kW; relative bandwidth, 10%; efficiency, 30%; gain, 41 dB. The main technical difficulty to realize the above performance comes from the wide bandwidth on such a low peak power level.

An Evaluation of Heat Dissipation Capability of Slow-Wave Structures

A new experimental evaluation method is presented for evaluating and comparing the heat dissipation capability of the slow-wave structures (SWSs) of helix traveling-wave tube (TWT). The practicality and simplicity of the evaluation method have been validated through experimental tests in some components with different assembling and processing methods, such as the cold stuffing, the heat shrink, the hot insertion, the molybdenum wrapping methods, and so on. Experimental results demonstrate that our evaluation method can be used effectively and conveniently to estimate and compare the thermal dissipation capability of the SWSs of the helix TWT

Thermal Analysis of a Helix TWT Slow-Wave Structure

A novel and effective analytical method using ANSYS has been developed for studying the heat-dissipation capability of a helix traveling-wave-tube slow-wave structure (SWS). This method, which is based on calibrating theoretical calculations with experimental data, is able to precisely predict the SWS heat dissipation, thereby reducing material costs and saving time. The consistency and feasibility of this method have been verified by experimental tests on SWSs using copper-plated helices and both BeO and BN support rods.

Research Progress on C -band Broadband Multibeam Klystron

Several types of C-band broadband multibeam klystrons (MBKs) are under development at the Institute of Electronics, Chinese Academy of Sciences. These MBKs operate at various C-band frequencies and have peak powers of 30-200 kW, average powers of 2-10 kW, and bandwidths of 4%-7%. The design considerations for obtaining high power and wide instantaneous bandwidths and test results for these MBKs are presented in this paper. The main technical problems, including a power sag in the band, high voltage breakdown, and non-operating mode oscillation, are also discussed. Further research work for improving the performance of these MBKs is described

Development of an S-band klystron with bandwidth of more than 11%

The development of an S-band klystron with bandwidth of more than 11% is introduced in this paper. At the peak power level of 800 kW, the efficiency of more than 30%, the gain of more than 40 dB, the equal-driving (constant input power across the bandwidth) relative instantaneous bandwidth of 11.2%, the average power of larger than 8.8 kW, and the power fluctuation within bandwidth of less than 1.5 dB are obtained in this klystron. The design considerations, simulation, and test results are presented and the techniques adopted to extend the bandwidth of the klystron are described

Researches on an

This paper reports the research work of an X-band sheet beam klystron with the aim of principle verification, which is fulfilled at the Institute of Electronics, Chinese Academy of Sciences. This paper includes two phases. The first phase is planned to build the sheet beam electron optics prototype tube using the closed periodically cusped magnetic focusing. The measured data shows that the rectangular beam with the cross section of 50 mm × 4 mm can propagate through ~ 300 mm from the cathode surface to the collector with the transmission of 92.4% at the voltage of 110 kV. This foregoing work successfully solves the beam formation and transportation and becomes the basis for developing the sheet beam klystron. In the second phase, the high-frequency interaction structure is designed and cold tested. The X-band sheet beam klystron is constructed and hot tested in the full voltage. The amplification characteristic can be observed near the voltage of 125 kV. For the drive power of 0.71 kW and the working frequency of 11.69 GHz, the output power of 2.8 MW is achieved with the 3 dB bandwidth of 30 MHz, and, correspondingly, the gain and the efficiency are 35.96 dB and 32.52%, respectively. At the same time, the beam transmission is 73.3%. An over 93% transmission is realized at the voltage of 135 kV, whereas the oscillation occurs in the tube. This research exhibits that the sheet beam klystron is a promising device for the high-power applications, whereas seeking the measures to overcome the oscillation is still an arduous task in the future.

X

The Institute of Electronics, Chinese Academy of Sciences, started developing X-band multibeam klystrons (MBKs) in 2000. Three types of X-band MBKs are currently under research and development; two types operate in the fundamental mode (TM010), and the other type operates in a high-order mode (coaxial TM310). These MBKs operate over the frequency range from 8 to 10 GHz and have peak powers of 50-100 kW, average powers of 2.5-5 kW, and bandwidths of 5%. The design considerations and testing results are presented in this paper. The technological problems, including nonhomogeneity of the RF electric field and low beam transmission, are also described. Further research work on the improvement of these MBKs is discussed.

-Band Sheet Beam Klystron

Several types of C-band broadband multi-beam klystron (MBK) are currently developing at the Institute of Electronics, Chinese Academy of Sciences (IECAS). These MBKs operate on the frequency range from low end to high end of C-band, and have peak power of 30-200kW, average power of 2-10kW, bandwidth of 4-7%. Careful design and experimental adjustment of the focusing system is very important for raising the DC beam transmission above 90% for C-band MBK with average power of 10kW. Experimental power-frequency characteristics for KC4079L are shown. There is good consistence between them. But there is some difference between the calculated and experimental gain-frequency characteristics

Research Progress on X-Band Multibeam Klystron

A linear theory for a rectangular waveguide cyclotron maser with a sheet electron beam is developed by using the Laplace transformation approach. This theory can be applied to any TEmn rectangular waveguide mode. The corresponding equations for the TMmn mode in the rectangular waveguide are also derived as a useful reference. Especially, the effect from the coupling between degenerate modes, which is induced by the nonideal rectangular waveguide walls, on the dispersion relation is considered in order to provide a more accurate model for the real devices. Through numerical calculations, the linear growth rate, launching loss, and spontaneous oscillations (caused by the absolute instability and backward wave oscillation) of this new structure can be analyzed in detail. It is worthwhile to point out that the operation at higher power levels of the rectangular waveguide sheet beam system is possible.

Research Progress on C-band Broadband Multi-Beam Klystron

The research progress on C-band Broadband Multi-Beam Klystron at IECAS were presented in this paper. The relative bandwidth of 8.1% and 8.5% for C-band Broadband MBKs KC4137 and KC4148 were obtained on the power level of 100kW and 160kW with efficiency of 29% and 32.5%. The reason of higher parasitic output was analysis, and the method for surpressing it was discuseed.