A 'non-local' response of the plasma core triggered by peripheral plasma perturbations other than laser ablation is found in the RTP tokamak. Oblique pellet injection (OPI) has been used to induce fast cooling of the peripheral plasma. In response, an inward cold pulse (Tedrop) and a slightly delayed core Terise are observed. A somewhat similar 'non-local' response is observed when the peripheral plasma is heated by modulated electron cyclotron heating or by fast current ramps, i.e. the core temperature drops in response to the peripheral heating. The plasma conditions for the occurrence of the 'non-local' response have been investigated. The core Terise following OPI is associated with the formation of a large temperature gradient in the region 1 < q < 2. The Terise is largest at low electron density and for large pellet deposition radii. Above a critical density the Terise disappears and only the (weaker) drop in core Teis observed. Time dependent transport simulations show that the propagation of the inward cold pulse is consistent with local transport, while the core Terise is a slower phenomenon requiring a large transient drop of χein the region 1 < q < 2.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics
Galli, P., Gorini, G., Mantica, P., Hogeweij, G. M. D., De Kloe, J., & Lopes Cardozo, N. J. (1999). 'Non-local' response of RTP ohmic plasmas to peripheral perturbations. Nuclear Fusion, 39(10), 1355 - 1368. https://doi.org/10.1088/0029-5515/39/10/301