感应电压叠加器次级非轴对称磁绝缘物理模型和数值分析

By introducing a parameter defined as an azimuthal mode number, the classical Creedon theory is generalized to two-dimensional situations, to describe the nonaxisymmetrical magnetic insulation caused by azimuthally asymmetrical dis-tributions of feed currents within cavity in induction voltage adders (IVA). A two-dimension Creedon model is developed, and the relationship of electrical parameters of the magnetic insulation (i.e., electric filed, magnetic flux density, electron den-sity, and electron sheath edge) depending on the relativistic factor, γ (r, θ), is derived. Given some boundary conditions, e.g., the azimuthal distributions of magnetic flux density on the cathode, the physical model is numerically solved, and the two-dimensional distribution of characteristics of the nonaxisymmetrical magnetic insulation of IVA is acquired. It is found that, as the magnetic flux density on the cathode satisfies the cosine distribution, the azimuthal distributions of electron sheath edges approximate the Gauss function. At the azimuthal positions close to injection points, the thickness of the elec-tron sheath is much thinner due to the stronger magnetic flux density, whereas the electron density is lower. The azimuthal uniformity of the magnetic flux density on the anode is much better than that of cathode, and the phase between them is about 180°, which are in agreement with the experiments on the RITS-3 facility. In addition, the physical model and numer-ical solutions presented in this paper are capable of describing the nonaxisymmetrical magnetic insulation caused by the off-center of inner electrodes in the long magnetically insulated transmission lines (MITL).