OVERVIEW OF HELIOTRON-E RESULTS

The Heliotron E device is characterized by a large aspect ratio, R/(a) over bar similar to 11, large rotational transform t(0) similar or eq ual to 0.5 and t((a) over bar) similar or equal to 2.5, higher shear, Theta = ((a) over bar(2)/R)(dt/dr)\(r=(a) over bar) similar or equal t o 0.5, an l = 2 and M = 19 helical coil, two vertical field coils and 19 toroidal coils (19 toroidal coils were removed to increase neutral beam injection (NBI) heating power up to 4 MW in 1985), where t is the rotational transform, (a) over bar is the average minor radius, R is the major radius, l is the pole number and M is the helical period num ber of the magnetic field. Theoretical characteristics of Heliotron E are summarized in section 2. Initial experiments in 1980-3 were mainly for studying ohmically heated plasmas. Topics relating to current-car rying plasmas are reviewed in section 3. In Heliotron E the first curr entless plasma was produced by ECRH using a gyrotron with a frequency of 28 GHz in 1982. Then the gyrotron frequency was increased to 53 GHz to produce higher density currentless plasmas. After NBI heating of t he target plasma produced by ECRH was successful, currentless plasmas were studied intensively in Heliotron E. In section 4, the production and heating of currentless plasmas by ECRH, NBI and ion cyclotron rang e of frequency (ICRF) are summarized. MHD properties of currentless He liotron E plasmas are summarized in section 5. Confinement and transpo rt are discussed for ECRH, NBI and ICRF plasmas in section 6. Characte ristics of edge plasma and plasma-wall interaction in Heliotron E are summarized in section 7. Configuration improvement and future directio ns based on Heliotron E results are discussed in section 8.