A New Type Of High Power Microwave Radiation Source Based On Metamaterials

In recent years, study on the theory and the application of the metamaterials has become a popular research direction in the world. In some developed countries, it has been taken into consideration as one of the important strategies. Especially, the design of microwave devices based on metamaterials is one of the most important branches.Comparing with the traditional vacuum electronic devices, the new type of vacuum electronic device based on the metamaterials has more advantages, such as high electronic efficiency, benefit to miniaturization, easy to assembly and so on. Among them, the backward wave oscillator based on metamaterials has better reflect the above advantages as the combination of metamaterials and the traditional backward wave tube.The main task of this thesis is to apply the metamaterials theory in the designing of the traditional backward wave oscillator to get a new type of high power microwave source device which can be used in S-band. Firstly, we give the introduction of the structure of Rod and the structure of CSRR which have negative electromagnetic properties. Through the structure evolution, we get the cell structure with negative electromagnetic properties which will be mainly researched in this thesis. Then we will give the magnetic properties of this new cell structure by simulation and the advantages and disadvantages of this new structure will be given by comparing with traditional coupled cavity structure. Secondly, this structure is applied to the design of a new type of high power microwave source slow-wave structure and two kinds of output designing scheme will be given. Besides, the geometric parameters of this slow wave structure will be optimized by simulation. Lastly, in view of the focusing magnetic field and the start current, this thesis gives the reasonable value range through the simulation. As a result, a new type of device operating in S-band is produced. It's peak output power can reach to 8.8 MW and the electronic efficiency can reach to 36%. Compared with the traditional backward wave device (1% to 15%), this device has a higher electronic efficiency.This thesis is divided into four parts, as follows:(1) Design of the cell structure with negative electromagnetic properties. To make the cell structure with negative electromagnetic properties through reasonable combination by using single negative cell structure. Then the electromagnetic characteristics are analyzed in detail through the simulation and the advantages and disadvantages will be described by comparing with traditional coupled cavity structure.(2) The study on the output coupler and the slow wave structure. We will give the reasonable range of period length and the number of period by using simulation to obtain a device which with higher output power and is smaller in size.On the basis of the coupling ring output structure, we conduct a research on the field distribution of slow wave structure. Eventually, a rectangular waveguide output structure which has higher electronic efficiency and is easy to assembly is given.(3) The study on the electrical parameters of the device. We will give the reasonable range of the focusing magnetic field and the start current, which will make convenience to the next experiment work.(4) The extensive study on the cell structure. For higher output power,two new type of cell structures with higher coupling impedance and wider working band will be given and be analyzed.