Tritium transport experiments on the JET tokamak

Abstract

An overview is given of the experimental method, the analysis technique and the results for trace tritium experiments conducted on the JET tokamak in 2003. Observations associated with events such as sawtooth collapses, neo-classical tearing modes and edge localized modes are described. Tritium transport is seen to approach neo-classical levels in the plasma core at high density and low q 95 , and in the transport barrier region of internal transport barrier (ITB) discharges. Tritium transport remains well above neo-classical levels in all other cases. The correlation of the measured tritium diffusion coefficient and convection velocity for normalized minor radii r/a = [0.65, 0.80] with the controllable parameters q 95 and plasma density are found to be consistent for all operational regimes (ELMy H-mode discharges with or without ion cyclotron frequency resonance heating, hybrid scenario and ITB discharges). Scaling with local physics parameters is best described by gyro-Bohm scaling with an additional inverse beta dependence.

Impurity transport due to electromagnetic drift wave turbulence

“…As seen in this figure in the ITG branch, the diffusivity shows a stronger dependence on b e , while the convection is less sensitive to b e . In agreement with experiments 12,13 and previous studies, 14 we observe that with increase of b e , the diffusivity strongly reduces, which is in direct relation to the stabilization of the ITG modes with increase of b e , see solid lines in Fig. 4(a).…”

“…12,13 Theoretical studies have confirmed these observations qualitatively, and it has been shown that an increase in b will result in a stabilization of the ITG modes leading to significant reduction of the impurity diffusivities.…”

Scaling of density peaking in JET H-modes and implications for ITER

“…The sign for the coefficient of T i /T e is consistent with predictions, as is the value obtained for χ/D≈1.3, which is close to a theoretical value (3/2) for turbulent transport [10]. This value of χ/D is also within the range of χ/D T obtained from experiments using trace amounts of tritium puffed into a large variety of JET discharges [13].…”

ITER relevant developments in neutron diagnostics during the JET Trace Tritium campaign

“…The neutron emission profile diagnostic played a key role in many TTE experiments [7][8][9]. This system was in operation during the 1997-DT1 [10] as well as during previous EFDA-JET campaigns.…”