Design And Optimization Of Magnetic Field Distribution In Gyro-TWTs

Gyro-TWT is a type of gyrotron device,which is an important high-power millimeter wave source.It is widely used in military and scientific research.The gyroTWT needs to be placed in the room temperature pore of the magnet system to keep key components of the gyro-amplifier in different magnetic fields.With the improvement of requirements for frequency,bandwidth and power in various fields,in addition to the performance improvement of devices and key components,new requirements for magnetic field distribution are also put forward,for example,specific curved profile magnetic field can increase the bandwidth,and the electron gun in high frequency band needs a magnetic field distribution with high magnetic compression ratio.The coil is the basic component of a magnet.This thesis studies the design of solenoid with the engineering requirements.Combined with the global optimization algorithm,synthesis of field distribution to coil parameters is realized considering both the magnetic field distribution and its gradient as the fitness function,and a uniform magnetic field and a gradual magnetic field distribution are designed through this method.In order to match the magnetic field distribution with the device structure,a fast calculation program is developed by studying the working principle of magnetron injection gun.Then the Ka-band magnetron injection gun is designed by using a structure with circular arc profile cathode and the collaborative optimization design of its structure and magnetic field.The working voltage is 40 kV and the working current is 10 A,the pitch ratio is 1.2 and the transverse velocity spread is 2.7%,the designed magnetic field compression ratio is 7.5.The G-band magnetron injection gun is also designed with the same design method.The working current is 3.5 A,the pitch ratio is 1.2 and the transverse velocity spread is 1.6%,the designed magnetic field compression ratio is 19.4.The magnet system is prone to tilt and displacement affecting the uniformity of the magnetic field during transportation and use,especially for radial magnetic field.The device has high requirements on the radial uniformity of magnetic field,and small magnetic field deviation may have a great effect on the performance of the device.Based on the offset of the magnet,the magnetic field distribution theory of magnet coil in offset state is deduced and verified by simulation.Finally,using the actual measurement data of a 2T superconducting magnet system and the global optimization algorithm,the displacement and tilt of the magnet are predicted.A displacement of 0.65 mm and a tilt angle of 0.16 ° has been predicted.The distribution trend of the theoretical data is computed with this parameter agrees with the measured data.