Development of Railgun Pellet Injector Using a Laser-Induced Plasma Armature Results of Dummy Pellet Acceleration Tests

摘要

Using the low electric energy railgun system, dummy pellet acceleration tests have been conducted to investigate the application of the electromagnetic railgun system for high-speed pellet injection intofusion plasmas. The primary objective of the development is to improve the pellet acceleration efficiency and durability of the rail materials. In the system, the pellet is pre-accelerated before railgun acceleration. A laser beam is used to induce plasma armature. The ignited plasma armature is accelerated by an electromagnetic force that accelerates the pellet. As low electric energy was used, rail materials were used for multiple operations. Tungsten-alloy rail provided longer durability and slightly higher energy conversion coefficient than copper rail. The energy conversion coefficient was from 0.3 to 0.5% using a plastic insulator. A ceramic insulator improved the energy conversioncoefficient by 80%. The highest pellet velocity was 1.7km/s using wooden pellets accelerated by 1m-long railgun. Based on the findings, it is estimated that the hydrogen pellet has the potential to be accelerated to 5km/s using a 3m-long railgun.