Compact Electric Power System for Fusion Reactor
The issue of the Tokamak fusion reactor is its large area occupied by its power supply, which is about half of the total building area for the International Thermonuclear Experimental Reactor (ITER), together with the compatibility between the site grid and Tokamak loads during the plasma operation period. ITER is now implemented with Tokamak, which requires about 1 GVar reactive power to compensate its power system for superconducting magnets where about 0.2 GVar is transferred from France Electrical Power Network, the other 0.75 GVar is generated by the system of reactive power compensation and harmonic filtering, the standard VSC configuration. ITER can experimentally generate 500-MW fusion thermal power in 400 s long pulse mode. It could only generate about 500 MW/3 = 167 MWe active electric power if it is to be configured with pressured water reactor due to the fact that it is only about 1/3 conversion efficiency from thermal energy to electric energy. For such fusion machine, the requirement for reactive power is much larger than the active power it generates. Based on this requirement, one efficiency and compact pulsed synchronous generator is suggested for this purpose. It can generate not only the fundamental reactive power to compensate and stabilize the power network with low internal impedance but also the active power for outputting power to the network with exciting controller of the generator. Due to its two purposes in one device configuration, it becomes compact and reliable by being implemented in the design of future fusion power plant for demonstration. Some consideration has been done to the special low impedance synchronous generator, which is intended for the concept design of Chinese Fusion Engineering Testing Reactor, targeting the compact electric power system for superconducting Tokamak fusion reactor.
System simulations and experiments for electrothermal-chemical guns powered by compulsators
The use of compulsators as a compact power supply has the potential to be used in electrogun applications. Although compulsators have been developed for electromagnetic railguns for some years, the use of compulsators in the power supply of electrothermal-chemical guns (ETCGs) may give rise to problems such as providing the proper current waveforms and matching of the capillary load. Of particular importance is the nonlinear characteristic resistance of the capillary load. This paper reports on a staged power supply system based on a compulsator for ETCG applications and describes the working process of the simulation system. The whole system is composed of a compulsator, a high-voltage capacitor, a capillary, a high-current thyristor switch, a power diode, and a control unit. The high-voltage capacitor is used for igniting the capillary arc, and helps to reduce the output voltage of the compulsator. Models of a compulsator and a capillary are considered as a whole to simulate the system performance. These models can be used to explain the discharge process of the capillary and provide the theory for the parameter choices and the power supply design. Experiments demonstrate that the staged power supply can meet the current and voltage requirements of ETCG applications.
A theoretical model for the physical processes in the confined high pressure discharges of electrothermal launchers
Different physical processes in confined high-pressure discharges are analyzed. The energy transport inside the discharge tube yields a radial temperature profile which has sharp gradients only near the tube walls. The regime at which such discharges can operate at a steady state is determined. For a given discharge ablation rate and plasma pressure, the tube length is limited. An analytical model is developed for confined high-pressure discharges operating in a quasi-steady-state in which the resulting plasma jet characteristics are steady at hydrodynamic timescales. This model allows the calculation of all the discharge parameters, such as ablation rate plasma temperature, resistivity, density and pressure as functions of the slowly varying current and the tube dimensions. The scaling laws obtained in this model are important for determining the impedance matching between the discharge and the power source and upgrading the discharge energy in electrothermal launchers to hypervelocities. Good agreement is obtained between the analytical model and experimental results at energies up to 100 kJ. >