Effects of compact torus injection on toroidal flow in the STOR-M tokamak

Abstract

In compact torus injection (CTI) experiments on the STOR-M tokamak, an ion Doppler spectrometer is installed to observe the effects of CTI on toroidal plasma flows. The intrinsic toroidal flow in ohmic discharges without CTI is sheared with counter plasma current flow in the core region and co-current direction at the periphery. With tangential CTI along the co-current direction, the flow velocity in the core region decreases by more than 5 km s −1 , while in the periphery the flow velocity increases by 3-4 km s −1 . These data indicate that the observed flow change is due to the injection of toroidal momentum. Density increase and high soft x-ray emission after CTI are observed during the changes in the toroidal flow.

Modification of toroidal flow velocity through momentum Injection by compact torus injection into the STOR-M tokamak

“…Suppression of the m = 2 MHD mode and transition to improved plasma confinement (H-mode) after tangential CTI have been observed [7]. It has also been recently found that the toroidal flow velocity can be modified by tangential CTI [5] and RMP fields [11] along with suppression of MHD fluctuations. In both RMP and tangential CTI cases, the change of the toroidal flow velocity was in the counter-clockwise (CCW, top view) direction, coincide with both CT injection direction and the plasma current direction.…”

“…The most probable location for the O V emission is around r = 3 cm. The IDS system for the STOR-M tokamak has a velocity resolution of ≈ v 1-2 km s −1 [5], determined by the range of the fluctuating spectral peak locations when the line of sight of the IDS system is in the minor radial direction.…”

“…CTs can be formed and accelerated inside a coaxial gun and can withstand high acceleration force to reach a high velocity [4]. CTI has the potential to control plasma pressure profile to optimise bootstrap current through precise control of the amount and deposition position of the fuel [5]. Also, CTI can be operated repetitively with high repetition frequency to provide a continuous and consistent fueling for fusion reactors [6].…”

Time evaluation of diamagnetic loop and Mirnov oscillations in a major plasma disruption and comparison with a normal shot

“…Among various tools of magnetic confinement, tokamak containing hot plasma is one of the best and developed devices [1]. Tokamaks are divided into two groups: first, the large tokamaks for studying large plasmas such as DIII-D [2] and Tore-Supra [3] with high-cost testing conditions and second, small tokamaks such as STOR-M [4] and ISTTOK [5] which have close relationship with the first group so that most of the experiments are initially carried out by them. One of the applications of tokamaks is in the field of nanoscience.…”

Investigation of rotation at the plasma edge in TCABR

“…In tokamaks, intrinsic countercurrent rotation is frequently observed in ohmic discharges. However, in some machines [9][10][11][12], co-current rotation is also observed at the plasma edge. In addition to the models that assume that momentum might be generated by the turbulence, during gas injection the radial friction force between neutral particles and ions/electrons, taking into account the poloidal magnetic field, may also drive toroidal rotation.…”