Measurement of the neutron spectra from beam-heated PLT plasmas

Abstract

MEASUREMENTS of the neutron spectra from the PLT tokamak plasma are reported here which provide information on the centre-of-mass velocity of the reacting deuteron pairs. The observation in PLT of no significant directed velocity yields additional evidence that the neuterons are produced by a thermonuclear process. Previous spectral measurements on other fusion devices have often determined that the neutron emission was non-thermonuclear and resulted from a small ‘tail’ component of energetic ions^1–3. The neutron spectra indicated a directed velocity of the reacting deuterons and thus non-thermonuclear neutron emission if the injected neutral beam ions were deuterium. In this condition, the neutron spectra were consistent with the expected beam-induced d(d,n) ³He reactions. However, if the heating beam used hydrogen, then the neutron spectra are consistent with a thermonuclear neutron emission resulting from the beam heating of the bulk deuterons in the plasma.