Measurements of the image fields in the STOR-1M tokamak

Measurements of the poloidal fields around the iron core transformer have been made in the STOR-1M tokamak (R = 22 cm, a = 3.5 cm, B/sub T/≤ 10 kG, I/sub p/≤8 kA, q(a) = 3.7) constructed for turbulent heating and high β experiments. In theoretical analyses, the finite length transformer leg was approximated by an infinitely long, infinitely permeable (μ=∞) cylinder. However, for the vertical magnetic field, surprisingly good agreement between theory and measurement has been observed. Measurements indicate that approximately one half of the required vertical magnetic field is self-provided by the plasma current as predicted theoretically