Two-dimensional modeling of a radially-convergent cylindrical inertial electrostatic confinement (IEC) fusion device.

摘要

The goal of this research was achieved by self-consistently modeling the discharge characteristics of the radially-convergent cylindrical inertial electrostatic confinement (RC-IEC) fusion device using a Monte Carlo numerical approach. The model (called MCP) is time-independent and spatially two-dimensional with three dimensions in energy and direction. Multiple particle species and collisions with background neutral gas are taken into account, and the electrostatic potential distribution is solved self-consistently with the particle production rate densities within the device. MCP determined the neutron source scaling, discharge characteristics (voltage-current-pressure relations), Star-mode light emission source, and the effects of gas rarification due to a non-uniform gas temperature distribution for an RC-IEC device.; The neutron yields predicted by MCP are in good agreement with experimental measurements (within 50%) from spherical discharge-IEC devices. The calculations indicate that 73–94% of fusions in discharge-IEC devices are due to molecular fast neutrals, and that neutron yield scales linearly with current for uniform background gas densities. Calculations of the effect of a non-uniform gas temperature indicate that gas rarification due to elevated gas temperatures is a likely cause of the experimentally observed decrease in neutron yield scaling at high current levels. The predicted operating pressure for the elevated temperature case is higher than in the uniform cases, but the neutron yield decreases.; The discharge characteristics predicted by MCP for the RC-IEC device are consistent with experimental results from similar spherical systems. As the pressure-distance product (the product of gas pressure and electrode separation distance) decreases, the operating voltage increases. Operating pressures range from 1.5 to 3.0 mTorr for voltages between 20kV and 60 kV. The space-charge dependent potentials calculated by MCP show that a virtual anode forms in the center of discharge-IEC devices that increases with increasing electric current.; De-excitation of charge-exchange fast neutrals is estimated as the dominant source of light in Star-mode beams, and electron-impact excitation is estimated as the dominant light source in the Star-mode core. The spatial distribution of these reactions is also in agreement with experimental observations.