Radiative improved mode in the HT-7 tokamak

Abstract The neon puffing for inducement of a Radiative Improved (RI) mode has been investigated on HT-7 tokamak. The results show that the central electron temperature is increased 1.4 times and electron density is strongly peaked with ne0/nGR about 0.7. It has an improved energy confinement (17–25 ms) and improved particle confinement (7.5–23 ms) at the same time. The confinement factor H (H = τe/ τ e ITER 93 ELMy-free ) of 0.96 is obtained. There is a large fraction of radiation power losses. In our cases it is up to 80% of total input power. This kind of plasma has a high Z-effective, but there is not detrimental concentration of the seeded impurity at the core plasma, which induce a reduction in the growth rate of Ion Temperature Gradient (ITG) driven modes. Fluctuation experimental measurement obtained by CO2 scattering with kθρs of 1.4 also shows a reduction of turbulence in the core plasma after neon seeding.