Interpretation of Sawtooth-Induced Changes of Neutron Emission in Joint European Torus Neutral Beam Injection Experiments

Based on a new theory for redistribution of fast ions during sawtooth crashes, numerical simulations are executed of sawtooth oscillations in the 2.5-MeV neutron emission from neutral beam injection-heated Joint European Torus (JET) plasmas. The analysis includes all sources of 2.5-MeV neutrons: thermal, beam-plasma, and beam-beam deuterium-deuterium reactions. Two models of sawteeth are used in the calculations—both based on magnetic field line reconnection. A detailed comparison with experimental results from JET shows that the theory for sawtooth-induced fast ion redistribution is consistent with the observed changes of the neutron emission.