The Headline-1 is dedicated to testing tungsten actively cooled plasma facing components under a tokamak environment. The first priority of Headline-1 is risk minimization of PFC procurement and operation in ITER. Headline-1 is focused on assessing the power handling capabilities of tungsten components both in terms of peak head load and ageing. Operation and physics issues that govern the power handling capability of WEST, as well as its control, are part of Headline-1.

Assessing the performance of the ITER like tungsten divertor under combined plasma loads in a tokamak environment (steady state and transient heat loads, combined particle/heat loads etc.) is a high priority issue to ensure efficient ITER operation.

As far as power handling is concerned, Headline-1 is focused on testing the ITER like tungsten divertor under relevant steady state heat fluxes (10-20 MW/m²) as well as under a large number of sub threshold transients (> 10⁵ ELMs). The modular design of the WEST divertor sectors provides a means to accommodate “à la carte” experiments such as testing different material grades, investigating monoblock geometry and shaping, ageing of pre-damaged or misaligned components, melting experiments, etc. It will also allow one comparing components supplied by different manufacturers.

Although focused on ITER divertor tungsten components, Headline-1 encompasses the power handling capability of all in-vessel PFC, including in particular the baffle and upper divertor as well as the ICRH antenna and LHCD launcher protections.

As far as PFC ageing is concerned, experiments with high integrated particle flux to the vessel walls, comparable to that of a nominal ITER discharge, are planned under Headline-1. The synergistic effects of combined exposure of the components to steady state heat loads / transient heat loads / high integrated particle flux, to be addressed within Headline-1 during WEST phase-2, is a high priority issue for ITER, as it might impact PFC lifetime and plasma performance.This part of the program relies on dedicated wall loading campaigns with repetitive long pulses, and includes the impact of helium operation on tungsten components. These WEST campaigns will be supplemented by thorough post-mortem analysis, allowing one to quantify wall erosion, changes in tungsten morphology of exposed surfaces, dust production and fuel retention.