Studies of Particle Behaviour in Heliotron E by Means of Balmer-Alpha Laser Fluorescence Spectroscopy

Abstract

Measurements of atomic hydrogen density profiles in Heliotron E plasmas were performed, where attention was focussed on the anisotropy of the profiles in the poloidal cross section. Obtained penetration profiles of atomic hydrogen agreed well with the Monte Carlo code calculations of the penetration of Franck-Condon neutrals when averaged electron densities \bar n e are larger than 10 19 m -3 . For \bar n e <10 19 m -3 , however, experimental profiles decreased steeper than calculated ones. Degree of the anisotropy of the neutral profiles in the poloidal cross section was also found to change with the value of \bar n e . Global particle confinement time τ p was evaluated from the measured atomic hydrogen profile. The results showed that τ p is arourud 20 ms for B =1 .9 T. In case of NBI plasma, τ p increases as increasing the magnetic field strength, while it decreases as increasing the absorbed power.