Reconciliation of Measured and TRANSP-calculated Neutron Emission Rates in the National Spherical Torus Experiment: Circa 2002-2005
Authors: S.S. Medley, D.S. Darrow, and A.L. Roquemore
Date of PPPL Report: June 2005
A change in the response of the neutron detectors on the National Spherical Torus Experiment occurred between the 2002–2003 and 2004 experimental run periods. An analysis of this behavior by investigating the neutron diagnostic operating conditions and comparing measured and TRANSP-calculated neutron rates is presented. Also a revised procedure for cross calibration of the neutron scintillator detectors with the fission chamber detectors was implemented that delivers good agreement amongst the measured neutron rates for all neutron detectors and all run periods. For L-mode discharges, the measured and TRANSP-calculated neutron rates now match closely for all run years. For H-mode discharges over the entire 2002–2004 period, the 2FG scintillator and fission chamber measurements match each other but imply a neutron deficit of 11.5% relative to the TRANSP-calculated neutron. The results of this report impose a modification on all of the previously used calibration factors for the entire neutron detector suite over the 2002–2004 period. A tabular summary of the new calibration factors is provided including certified calibration factors for the 2005 run.