The configuration of the Joint European Torus (JET) has changed several times in the past, the most recent change in 2009/2010 being the replacement of the carbon plasma-facing wall with the ‘ITER-like wall’; a combination of beryllium, tungsten and carbon. Each upgrade of the torus affects the neutron field and hence the calibration factors for individual neutron detector systems. The paper presents calculations of the major contributors to the change in the diagnostics response for past stages of the JET torus. The emphasis is on the most important in-vessel neutron diagnostics – the activation system – and in particular the irradiation location in Octant 3 (so called KN2-3U). The most important changes were found to be the introduction of mushroom limiters close to the KN2-3U, which have been not adequately modeled in the previous models of JET, resulting in an inadequate calibration factor for this diagnostics. The re-calculation will thus affect the calculation of the fusion power also for past experiments.
COBISS.SI-ID: 27626791
The power output of fusion experiments and fusion reactor-like devices is measured in terms of the neutron yields which relate directly to the fusion yield. In this paper we describe the devices and methods used to make the new in-situ calibration of JET in March 2013 and its early results. We discuss the constraints and main calibration approach, e.g. the choice of source type and the deployment method including first results.
COBISS.SI-ID: 27622439