Recent expansion of the TFTR multichannel neutron collimator

Radial neutron emission profiles from TFTR DT plasmas are generally narrow and highly peaked. In the past, the neutron profile monitor provided inadequate coverage of the plasma core for these peaked profiles. Four new sight lines were added to improve the view in the central region and better evaluate parameters such as global neutron yields and neutron peakedness and to localize neutron MHD activity. The new sightlines utilize plastic scintillators instead of the original ZnS based NE451 detectors. These new detectors have larger volumes and increased solid angles as compared to the NE451 detectors in order to increase the incident neutron flux, in order to reduce statistical open-quotes shot noiseclose quotes on the signal traces and improve the frequency response. The increased detection capabilities along with recent upgrades in the fast amplifiers and wave form digitizers have extended the frequency response to >50 kHz which allows the study of high frequency MHD activity. Data from DT plasmas illustrating the enhanced spatial and temporal resolution with the new channels are presented. copyright 1997 American Institute of Physics