Following impurity injection by laser ablation (LA) in JET plasmas, the electron temperature, Te, is observed to drop at a rate that cannot be accounted for by changes in radiated power, ΔPrad. Testarts to drop promptly over a large fraction of the plasma volume, which can be explained by a non-local change in electron heat diffusivity. The change in diffusivity, Δχe, is generally short lived, lasting a few milliseconds, even if ΔPradcan persist for longer times. No clear relation between ΔPradand the strength of the prompt plasma response to LA can be observed, but only those events with ΔPrad/Prad> 0.5 give rise to detectable Teperturbations. In hot ion H mode plasmas, Δχeis found to be spatially non-uniform and increasing exponentially with the time delay of the LA relative to the onset of the H mode. Examples of non-monotonic Δχeprofiles are found in plasmas of lower heating power. Energy transport models combining local and non-local (or strongly non-linear) features are possible candidates for an explanation of these observations.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics
Galli, P., Cherubini, A., De Angelis, R., De Luca, F., Erba, M., Giannella, R., ... Taroni, A. (1998). Transient heat transport studies using laser ablated impurity injection in jet. Nuclear Fusion, 38(9), 1355 - 1371. https://doi.org/10.1088/0029-5515/38/9/310