WEST first plasma operation with all tungsten plasma facing components

The transformation of Tore Supra into WEST, from limited to diverted magnetic configuration and from carbon to tungsten plasma facing components was completed at the end of 2016.

Plasma breakdown was readily obtained. Plasma current ramp up to 800 kA was achieved after the alteration of in-vessel copper passive structures. The operational window was narrow: at lower prefill pressure, no breakdown occurred while at higher prefill pressure, transition to electron slideaway discharges happened. After a first boronization, performed in July 2018, plasma startup window opened up. Slideaway electron discharges disappeared and higher plasma density was reached. Dedicated PFC diagnostics allow for first power deposition studies.

So far, up to 2.8 MW of LHCD and 0.6 MW of ICRH have been injected into the plasma with a fraction of radiative power around 60%. The radial electric field (measured by Doppler reflectometer) deepens inside the separatrix with additional power, although H mode has not be reached yet.

The ongoing phase of operation is dedicated to H mode access and test of the ITER-like plasma facing unit prototypes. A full ITER like actively cooled lower divertor will be installed in 2019. In this 2nd phase, the pulse length will be extended to 1000s.