Throat and vented pump limiters particle collection experiments with auxiliary heating in Tore Supra

Particle collection experiments using one throat pump limiter and one vented pump limiter (hereafter Throat-FL and Vented-FL, respectively) are reported for discharges with additional power (D-2 fuelling, I-p = 1 divided by 1.3 MA, [n(e)] approximate to 2 divided by 5 x 10(19) m(-3), P-tot up to 6.6 MW). Since both limiters have the same area (0.16 m(2)), a direct comparison of pressures and exhaust efficiencies is possible. It is shown that the neutral pressure (II) in the plena of both the Vented and Throat-PLs increases with additional power and volume averaged density proportionally to [n(e)]P-2(tot)1/3. The collection efficiencies (eta(coll)), which are also experimentally estimated, are constant in the range of power and density considered (with values approximate to 12% for the Throat-PL, and 4% for the Vented-PL). These experiments are interpreted with the help of a model of ions and neutrals recirculation in the SOL. The ratio of the calculated pumping efficiencies (epsilon(pump)) Of both devices remains roughly constant with increasing power and density. The flux amplification factor (f) and the particle exhaust efficiency are calculated to vary with the conducted power proportionally to P-cond(1/3) and the particle lifetime (tau(p)) to decrease as P-cond(-1/5).