Xiaohan Sun

Research on traveling wave tube body temperature distribution

The paper describes simulation result of traveling wave tube(TWT) body temperature, and establishes a temperature measurement system based on the fiber bragg grating(FBG) sensor array. By quasi-distributed FBG sensing, the system can measure TWT body temperature distribution accurately.

Noise performance analyses for TWT electron gun

A noise performance analytical model considering shot noise and velocity noise was proposed for TWT electron gun. Simulations show that electron beam conformations and velocity distributions can be influenced apparently by the noises. And current & velocity fluctuations were simulated, with equivalent distributed noise impedances calculated from it. Starting from structure and operation parameters of electron gun, the model shows to be an effective tool for electron gun noise performance analysis and design.

An Evaluation of Heat Dissipation Capability of Slow-wave Structure by Micro Fiber Bragg Grating Sensor Array

We proposed a novel evaluation method of heat dissipation capability of the helix slow-wave structure (SWS). A distributed micro fiber Bragg grating (FBG) sensor array is designed to measure the temperature distribution of the helix in SWS. An experiment on two X-band SWSs of different heat dissipation capability is made and the results show that our method can effectively be used to estimate and distinguish the heat dissipation capability of SWS.

Rayleigh scattering measurement of residual gas inside microwave vacuum electronic devices

We propose a method to measure the residual gas in microwave vacuum electronic devices (VED) in long-term storage based on Rayleigh scattering, and establish the relation between the gas state and the intensity of scattered light. This method can be used to monitor the status of VED in long-term storage.

Electromagnetic band gap substrate for planar microstrip meander line travelling wave tube

Novel dual-square electromagnetic band gap (EBG) substrate is investigated to improve the performance of planar microstrip meander line travelling-wave tube (MML-TWT). According to the simulation results, this EBG structure can improve coupling impedance double and extend bandwidth from 9.5GHz to 10.5GHz. This structure also can be fabricated in one-dimensional for the MML-TWT. In other words, it has same transverse dimension of MML-TWT, which is important to fabricate the planar travelling wave tube.

Testing-based estimation method for inner temperature distribution of TWT collector and output terminal

A testing-based estimation method for inner temperature distribution of collector and output terminal is proposed without placing temperature sensors inside the traveling wave tube. The inner temperature distribution is estimated based on testing body temperatures, with an iteration solving the thermodynamic parameters of the thermal model. The results indicated that the method has good feasibility and accuracy.

Performance degradation simulation for M-type cathode based on ion bombardment

Simulation of M-type cathode performance degradation is studied based on ion bombardment with interdiffusion effect considered. Sputtered volume, sputter distribution and ion spot occurrence time can be estimated, with estimated sputtered volume close to former researches. For M-type Re-coated cathode with 300nm-thick film, ion spots were estimated to appear after 2.06×105 hs working.

S-shaped microstrip meander-line slow-wave structure for W-band traveling-wave tube

S-type microstrip meander-line slow wave structure was designed and simulated. The effects of different structural parameters on the new structure were analyzed. The simulation results show that this microstrip meander-line slow wave structure has a similar dispersion characteristic with the traditional structure, and the center frequency expands to the higher frequency. The transmission loss and coupling impedance is greatly improved in high frequency range.

Temperature dynamic response of slow-wave structure of space traveling wave tube

The thermal condition of slow-wave structure is very important to the normal and stable work of the space traveling wave tube. This paper theoretically analyzes dynamic response of helical slow-wave structure, and simulates it with the help of ANSYS., The dynamic response of temperature under different pulse duration and duty cycle is acquired through analysis and simulation.

Multiple electron beam helix TWT for the active phased array radar system

In order to apply the traveling wave tubes (TWTs) in the active phased array radar system, new mini-TWT, i.e., multiple electron beam helix TWT (MBTWT) is studied. It is made by putting 3 helixes and electron beams into one metal tube and one PPM focus system. They have common electron gun and collector. The electron gun has a common heater and 3 emitting cathode heads which produce 3 electron beams. The collector has 3 electron beam collecting channels. This structure will form 3 TWT amplifiers and loosen the size requirement to TWT for its application in the active phased array radar system.