Design and Construction of a New Reversed Field Pinch Device with a Very Small Aspect Ratio (A˜2)

A new RFP device with a very small aspect ratio (A = 2.1) is designed and constructed. The aspect ratio of A = 2.1 is much smaller than those of existing devices (A > 3). At this small A, no rational magnetic surface appears from the axis to ψ = 0.4 in the normalized flux surface coordinate, which may reduce the chaotic properties of the plasma in the core region. The proposed examination of bootstrap current generation could also be done. For this new device, a compact and high voltage center coil and an aluminum vacuum vessel (R/rw = 0.53 m/0.25 m) are developed. The maximum plasma current is designed to attain 100 kA. The construction of the device has been completed successfully. In the initial series of discharges, a stable region with a very high Θ value up to ˜2.5 is newly found.