Neutron Field Parameter Measurements on the JET Tokamak by Means of Super-Heated Fluid Detectors
The neutron field parameters (fluence and energy distribution) at a specific location outside the JET Torus Hall have been measured by means of super-heated fluid detectors (or "bubble detectors") in combination with an independent, time-of-flight, technique. The bubble detector assemblies were placed at the end of a vertical line of sight at about 16m from the tokamak mid plane. Spatial distributions of the neutron fluence along the radial and toroidal directions have been obtained using two-dimensional arrays of bubble detectors. Using a set of three bubble detector spectrometers the neutron energy distribution was determined over a broad energy range, from about 10keV to above 10MeV, with an energy resolution of about 30% at 2.5MeV. The very broad energy response allowed for the identification of energy features far from the main fusion component (around 2.45MeV for deuterium discharges).