Modelling of core tungsten transport and its control in ITER H-mode scenarios

摘要

1. Introduction The decision to start ITER operation in the non-active phase (H/He plasmas) with a W divertor has brought increased attention to physics issues related to high Z impurity transport and control. Lack of impurity control could lead to the radiative collapse of plasmas by W accumulation and increased disruptivity, which is detrimental to ITER operation. Control of W in H-mode plasmas requires, as a first step, the control of W production and its transport into the core plasma through the SOL and edge transport barrier. In addition, even when the concentration of W at the pedestal is kept at low levels, unfavourable core W transport can lead to its uncontrolled accumulation and to loss of the H-mode due increased radiation in present experiments (e.g. JET and ASDEX-Upgrade) [1, 2], where schemes have been developed to avoid W accumulation by the application of additional heating to provide stable H-mode operation with W plasma facing components.