Planned upgrade to the coaxial plasma source facility for high heat flux plasma flows relevant to tokamak disruption simulations

Plasma disruptions in tokamaks remain serious obstacles to the demonstration of economical fusion power. Although the symptoms of major disruptions are often recognizable, the disruptions themselves remain generally unpreventable. Therefore, it is necessary to design next generation tokamaks to withstand many of these disruption events and the associated high heat loads to the material surface. A suitable environment is needed to study the effects of major disruptions on candidate tokamak plasma facing component materials (PFCs). High heat flux disruption simulation experiments create such an environment. Many materials studies have been performed under high heat flux conditions approaching those expected during a disruption, but with little conclusive evidence to base strong support for the choice of one PFC material. In these disruption simulation experiments, some important effects have not been taken into account. Present disruption simulation experimental deter do not include effects of the high magnetic fields expected near the PFCs in a tokamak major disruption. In addition, temporal and spatial scales are much too short in present simulation devices to be of direct relevance to tokamak disruptions. A further complication is that among the present simulators there are a variety of energy sources employed, including electron beams, lasers, and radiation sources in addition to plasma sources. Their applicability to tokamak plasma conditions is in question. To address some of these inadequacies, an experimental program is planned at North Carolina State University employing an upgrade to the Coaxial Plasma Source (CPS-1) magnetized coaxial plasma gun facility. The advantages of the CPS-1 plasma source over present disruption simulation devices include the ability to irradiate large material samples (to ~100 cm²) at extremely high areal energy densities (1-20 MJ/m²), and the ability to perform these material studies in the presence of a high magnetic field (up to 10T arbitrary oblique orientation). Other tokamak disruption relevant features of CPS-1U include a high ion temperature (T_⩾ 100 eV), high electron temperature (T_e≈20-50 eV), and long pulse length (0.5-1.0 ms)