Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines(MITLs),resulting in disturbed electron flow and non-negligible current los...Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines(MITLs),resulting in disturbed electron flow and non-negligible current loss.In this paper,3 D particle-in-cell simulations are conducted with UNPIC-3 d to investigate the current loss mechanism and the influence of the input parameters of the coaxial-disk transition on current loss in an MITL system.The results reveal that the magnetic field non-uniformity causes major current loss in the MITL after the coaxialdisk transition,and the non-uniformity decreases with the distance away from the transition.The uniformity of the magnetic field is improved when increasing the number of feed lines of a linear transformer driver-based accelerator with coaxial-disk transitions.The number of input feed lines should be no less than four in the azimuthal distribution to obtain acceptable uniformity of the magnetic field.To make the ratio of the current loss to the total current of the accelerator less than 2%at peak anode current,the ratio of the current in each feed line to the total current should be no less than 8%.展开更多
In this paper, we examine the unsteady magneto hydrodynamic (MHD) flow generated by a disc that is making non-coaxial rotations with a third grade fluid at infinity and moving with a variable acceleration. The fluid i...In this paper, we examine the unsteady magneto hydrodynamic (MHD) flow generated by a disc that is making non-coaxial rotations with a third grade fluid at infinity and moving with a variable acceleration. The fluid is assumed to satisfy slip boundary condition on the disc. The governing equations are three dimensional and highly non-linear in nature. The assumed slip boundary condition is non-linear as well. The governing equations are transformed to a nonlinear boundary value problem which is solved numerically. Comparison of this generalized problem with uniformly accelerated disk satisfying no slip condition is made. Variations of the characterizing dimensionless parameters such as slip parameter λ, acceleration parameter c, unsteady parameter τ, third grade parameter β, suction parameter S, and magnetic parameter N on the flow field are discussed and analyzed graphically.展开更多
基金supported by National Natural Science Foundation of China(Nos.U1530133 and 52007152)the Special Foundation of State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(No.SKLIPR2005)the Youth Innovation Team of Shaanxi Universities。
文摘Coaxial-disk transitions can generate non-uniform magnetic fields and abrupt impedance variations in magnetically insulated transmission lines(MITLs),resulting in disturbed electron flow and non-negligible current loss.In this paper,3 D particle-in-cell simulations are conducted with UNPIC-3 d to investigate the current loss mechanism and the influence of the input parameters of the coaxial-disk transition on current loss in an MITL system.The results reveal that the magnetic field non-uniformity causes major current loss in the MITL after the coaxialdisk transition,and the non-uniformity decreases with the distance away from the transition.The uniformity of the magnetic field is improved when increasing the number of feed lines of a linear transformer driver-based accelerator with coaxial-disk transitions.The number of input feed lines should be no less than four in the azimuthal distribution to obtain acceptable uniformity of the magnetic field.To make the ratio of the current loss to the total current of the accelerator less than 2%at peak anode current,the ratio of the current in each feed line to the total current should be no less than 8%.
文摘In this paper, we examine the unsteady magneto hydrodynamic (MHD) flow generated by a disc that is making non-coaxial rotations with a third grade fluid at infinity and moving with a variable acceleration. The fluid is assumed to satisfy slip boundary condition on the disc. The governing equations are three dimensional and highly non-linear in nature. The assumed slip boundary condition is non-linear as well. The governing equations are transformed to a nonlinear boundary value problem which is solved numerically. Comparison of this generalized problem with uniformly accelerated disk satisfying no slip condition is made. Variations of the characterizing dimensionless parameters such as slip parameter λ, acceleration parameter c, unsteady parameter τ, third grade parameter β, suction parameter S, and magnetic parameter N on the flow field are discussed and analyzed graphically.
