Design and simulation of NBI heating system using high dense helicon plasma source for Damavand Tokamak
Abstract A neutral beam injection system by using standard COMSOL software is designed and simulated for plasma heating of small size Damavand tokamak. In context of theoretical model, the needed heat power for plasma heating of this tokamak to the specified temperature is estimated. The number of particles per second, power and energy of the neutral beam which is needed to reach the intended heat power are calculated. Based on these parameters, all sections of the neutral beam injection system such as the plasma source, the extractor, the accelerator, the neutralizer and the charge particles deflector system, are designed and simulated. A dense helicon plasma source, with nonuniform magnetic field configuration, is employed as a plasma source of the device. This helicon plasma source is designed and simulated according to the estimated parameters. Considering the beam optics and space-charge effects, an ion extractor system is simulated and designed for this device. This extractor system can extract an ion beam with current about 7.5 A. The simulation results show that a neutral beam with energy 4.45 KeV and particle current about 6.6 particle per second can be obtained from our designed NBI system. This neutral beam can heat the electrons of plasma to temperature 300 eV and ions to 150 eV. On the other hand, the results of the simulation indicate that our designed neutralizer system could neutralize about 90.58 percent of the initial input ions. In this context, the proper parameters (the neutral beam energy and power) of the NBI systems are calculated for heating of the electrons and ions of the plasma to temperature 1000 eV and 500 eV, respectively.