High density experiments with gas puffing and ECRH in T-10

High density experiments were carried out in T-10 with gas puffing and electron cyclotron resonance heating (with absorbed power value up to 1.4 MW) with oblique and perpendicular power launch. Densities exceeding the Greenwald limit (n(Gw)) by up to a factor of 1.8 were achieved in a regime with a high value of the edge safety factor at the current flat-top, q (a) congruent to 8.2. The decrease of q (a) to a value of 3 led to the reduction of the ratio (n(e))lim/n(Gw) to 1. Confinement degradation with density increase was not significant up to the density limit. However, the typical T-10 linear increase of energy confinement time with density saturates at n(e) greater than or equal to 0.6n(Gw). This saturation is the result of the development of an additional transport in the electron heat channel. However, the saturated tau(E) values exceeded the ITER L-mode scaling predictions by up to a factor of 1.2 and were close to the value predicted by the ITER H-mode scaling. Effect of the strong gas puffing on the plasma confinement and experiments with neon seeding are also discussed in this paper.