Nonlocal Transient Transport and Thermal Barriers in Rijnhuizen Tokamak Project Plasmas

In the Rijnhuizen Tokamak Project plasmas, a transient rise of the core electron temperature is observed when hydrogen pellets are injected tangentially to induce fast cooling of the peripheral region. High-resolution Thomson scattering measurements show that the $T_e$ rise is associated with large temperature gradients in the region $1<q<\mathrm{}2\mathrm{}$. This region acts as a layer of transiently increased thermal resistivity (transport barrier) when probed by fast heat pulses from modulated electron cyclotron heating.