First Experiment on Levitation and Plasma With HTS Magnet in the RT-1 Plasma Device

Abstract

The high temperature superconducting (HTS) floating magnet of the ring trap 1 (RT-1) reached the first experiment on levitation and plasma. The magnet using an HTS coil was levitated stably by levitation coil, and plasma was produced around the ring-shaped HTS magnet by electron cyclotron heating with 8.2 GHz microwave. This novel plasma device was constructed at the University of Tokyo to explore means of achieving the advanced-fuel fusion. The plasma confinement mechanism is based on the concept of high-beta relaxed state that is self-organized within flowing plasma. The HTS magnet is operated in a persistent-current mode and magnetically levitated in a plasma vacuum chamber. The weight of the HTS magnet is about 110 kg. Initially the HTS coil is cooled below 20 K by an external cooling system with detachable transfer tubes. After the transfer tubes are detached, an experiment of levitation and plasma is conducted while the HTS coil temperature remains within the range of 20 K-32 K without cooling. This paper describes the HTS coil design and test results of the HTS magnet as follows; an initial cooling, a persistent-current operation without cooling and the first levitation and the first plasma experiment.