Atomic hydrogen behaviour in Heliotron E

In order to understand atomic hydrogen behaviour and particle confinement properties in Heliotron E plasmas, techniques of laser induced fluorescence (LIF) have been extensively used, combined with measurements of absolute Balmer alpha emissions and density fluctuations. The results revealed that for an average electron density n ̄_e > 1.5 × 10¹⁹ m^-3, Hα fluorescence allowed the measurements of atomic hydrogen densities and yielded the recycled Franck-Condon neutrals (~ 3 eV) to penetrate into core plasmas, whereas for n ̄_e < 1.0 × 10¹⁹ m^-3, such measurements were perturbed by dissociative-excitation of H₂ molecules into the n = 2 state. Also, the global confinement times showed a clear correlation with electron density fluctuations.