Particle and energy balance analysis of a currentless high beta plasma in Heliotron E

Abstract
An ion and electron energy balance analysis has been made of the MHD stable high beta plasma produced by neutral beam injection in Heliotron E. The currentless target plasma was generated by 53.2 GHz second-harmonic ECH (~ 160 kW) at a magnetic field of Bh = 0.94 T. The linear density rise due to intense gas puffing during neutral beam injection increased the volume averaged beta value up to ≈ 1.5 − 2.0%. The results of 1-D transport codes show that the global energy balance is dominated by the electron loss channels in which radiation is predominant. The particle balance in the beam-assisted density rise phase cannot be accounted for without an inward convection of bulk particles, indicating a similarity to the transport of impurities. So far, the observed beta values are not restricted by MHD activity.