Ignitor-like Toroidal Devices for Neutron Production

Compact fusion toroidal machines operating in DT have the potential to become efficient sources of neutrons for material testing. An Ignitor-like device could be envisaged for this purpose, making full use of the intense neutron flux that it can generate without reaching ignition. Preliminary radiation damage estimates for some fusion-relevant materials\footnote{F. Bombarda, B. Coppi, et al., \textit{Fus. Eng. Des.} \textbf{86},2632 (2011)} have shown that few full-power months of operation would provide adequate dpa levels. The main features and technological issues of a High Field Neutron Source Facility based on the Columbus concept,\footnote{B. Coppi and M.F. Salvetti, \textit{MIT Report PTP02/06}, (2002)} with about 50\% more volume than Ignitor, are illustrated and discussed. Optimization of the plasma temperature and density relative to the reference ignition scenario (with the assistance of auxiliary heating power) can achieve considerable reductions of duty cycle requirements. The constraints imposed by flux availability, magnet heating and wall loading will inevitably impose a complete redesign of the machine, with the adoption of novel materials (such as MgB$_2$ superconductor already adopted for Ignitor), and new modes of operation will need be investigated.