Investigation Of Microwave Generator With A Conical Slow-Wave Structure Operating Without Guiding Magnetic Field

In this paper, a type of microwave generator with a conical slow-wave structure is put forward, which is based on the high-power microwave oscillators, especially on the high-power oscillators operating without external magnetic field. The device has some new features such as no collector, operation without external magnetic field, simple structure and easy extraction of microwaves. The device is studied with 2.5 - dimensional particle-in-cell ( PIC ) code. A series of parameters are optimized for the fabrication of the device.The effect of the structure parameters on microwave output power and frequency is studied by the use of the PIC code, and reasonable explains are given. The results show that when the period of the slow-wave structure changes from 1.5 cm to 1.9 cm, the range of microwave frequency is 4.33 GHz-4.74 GHz, which belongs to the C band; With the increasing of the period, microwave frequency decreases. In the slow-wave structure, the vane's thickness and its gap have a certain effect on microwave output. With the diode voltage and electron beam current fixed, the increasing of the absorptive rate of foil results in the decrease of microwave output power, but these kinds of changes have little effect on microwave frequency.The effect of diode voltage and electron beam current is studied, too. With the device parameters optimized, a high-power microwave is obtained with an output power of 2.3 GW and an operation frequency of 4.74 GHz when diode voltage of 650kV and electron beam current of 12 kA is applied.Finally, according to the optimized parameters, the experiment device using a conical slow-wave structure- a type of microwave generator with no collector is fabricated. Related preparations are made for the next experiment work.