Neutron Emission Profile Monitor

Measurement of emission profile of 2.45MeV neutron generated by d(d,n)He3 reaction in the deuterium plasma. This measurement is very useful to know the fusion performance and the ion temperature profile.

[Diagnostic Method]
The instrument of Neutron Emission Profile Monitor comprise fan-shaped 6 channel collimator array (2.6m1.3m1.6m) viewing a poloidal cross section. This collimator array is located about 5m away from the center of plasma. The collimator of each channel consists of Polyethylene and lead for shielding against neutron from out of the viewing line of each channel and reduction of gamma-ray backscattered from the external structures of JT-60U device, respectively.

Conventional fast neutron detectors based on NE213 liquid organic scintillator with the good time resolution situated at the end of each collimator channel record neutron emission data, which are stored as time trace in the JT-60 database.

However, since this data is the line-integrated signal along the line-of sights of each channel, the neutron emission profile is estimated by carried out Abel inversion of these dates.

1f1 NE213 liquid organic scintillator

Number of channel : 6
Time resolution : 10 ms
Position : In front of the above port in P18 section