Simulation and Experiments with Rail Gun for High Speed Pellet Injection

Abstract

A tokamak is a machine producing a toroidal (doughnut-shaped) magnetic field for confining a plasma. Fusion power reactors based on tokomak concept use isotopes of hydrogen like deuterium, tritium as fuel, there are several ways to replenish the spent fuel. Successful fuelling in tokomaks requires that the time needed for the fuel to penetrate injected material is disassembled, ionized and captured by the local magnetic field. Fueling of plasma device can be done by gas injection or pellet injection methods. High-speed hydrogen ice injection (pellet injection) is the dominant refueling method. The method of injection fuel (hydrogen pellets) consists of condensing the H2 isotopes to form solids (pellets), accelerating it to high speeds, transporting the pellet deep into plasma core. The experimental devices like centrifuge or pneumatic devices meeting the fueling requirement with difficult due to large size and high electron densities & temperature of the plasma. Hypervelocity pellets of a substantial size need to injected into the plasma continuously at high repetition rates. Advanced technologies, such as rail gun pellet injector are being developed to meet such demands. This designing of rail gun is based upon the required velocity and armature & rail sizes. The proper design of rail gun requires a special consideration of the interaction between the proper design of power supply on one hand and exact mechanical design of rails, barrel and armature on other hand. The dissertation work involves designing and developing a rail gun by taking the effect of rail & armature geometry, current distribution into the rails and inductance gradient on acceleration of armature into consideration. Railgun is designed by taking the velocity requirement into consideration. According the design, the railgun is developed and tested for various velocities. The analysis of various parameters like rails, coating of lubricant on rails, and different power supplies was carried out to test the railgun performance.