EXPERIMENTAL INVESTIGATION OF THE MAGNETIC-STRUCTURE IN THE H-1 HELIAC

The results of an experimental study of the magnetic structure in the H-l heliac are presented. Electron beam magnetic mapping has confirmed the existence of closed nested flux surfaces, in good agreement with a computer model. Measurements over a wide range of helical winding cu rrents demonstrated a variety of attainable magnetic configurations wi thin a rotational transform range of 0.6 less than or equal to t(0) le ss than or equal to 1.8. The observed islands can be attributed to ded uced small errors in the coil alignment in H-l. A magnetic island stud y and a correction in the model to fit the experimental observations r evealed the error sources in the magnetic field.