Compact toroid (CT) injection is a viable technology for fuelling large tokamak reactors in the future. Experimental demonstration of CT injection has thus far been conducted using horizontal injection in the midplane of tokamak devices. However, recent analyses indicate adverse effects of the toroidal magnetic field on CT injection. In order to avoid these adverse effects, the CT would need to be injectable in any direction. We have therefore devised a curved drift tube to change the direction of CT propagation and have experimentally demonstrated its efficacy. It has been observed that a CT can be transported smoothly through curved drift tubes with 45° and 90° bends without any appreciable change in the CT parameters. The magnetic field, electron density and speed of CTs transported through both 45° and 90° bends are similar to those observed in a linear drift tube.
Experimental studies of the dynamics of compact toroid injected into the JFT-2M tokamak