A pulse forming network for toroidal field system for TPM-1U Tokamak

Abstract

Summary form only given. TPM-1U is a small size tokamak, with a vacuum vessel of 0.15 m minor radius and 0.4 m major radius, with an expected magnetic field in the torus center of 0.5 T and a plasma current above 150 kA. One of the goals of the TPM-1U is to establish the scientific and technological base for the study of magnetically confined high temperature plasmas in Mexico, and get technical and scientific goals such as plasma-wall interaction studies, development of new diagnostics and exploration of new magnetic topologies. Analysis and design procedure of pulse forming network (PFN) of current, which is used for power the array of the toroidal coils field system for Tokamak TPM -1U is presented , given the characteristics of the pulse current waveform (duration, magnitude and rise time ) required to produce a magnetic field of 0.5 T. The network consists of a number of parallel branches, each of these consists of a capacitor in series with an inductor. The design process of the network is to determine the values of capacitors and inductors that compose it, so that with these values for the network output pulse stream with the desired characteristics. This determination is made by the decomposition of the pulse in a Fourier series, the coefficients are determined, and considering the rate of discharge of the electric elements the correlation between the Fourier coefficients and the values of the electrical elements of each stage is found, and the result is a PFN Type C. Subsequently, an approximation is used to transform the PFN of Type C to Type E network, both originally proposed by Guillemin [1]. The advantage of network type E is that it consists in the arrangement of capacitors with the same value for all stages, facilitating construction. Finally, the simulation results are shown in ATP (Alternative Transient Program) of both types of network for comparison purposes, considering different parameters in terms of the formation of the current waveform firstly to a load pure resistive.