Triton Burn-Up Measurements in JET Using Neutron Activation Technique

The confinement and slowing down of fast tritons in JET deuterium plasmas have been investigated by measuring the 14. 1MeV to 2.45MeV neutron production ratio which is a direct measure of the triton burn-up fraction. The 14.1MeV neutron production was measured by means of the activation of Copper samples and the 2.45MeV neutron production was obtained from fission chambers. Data were obtained for different plasma conditions giving burn-up fractions in the range 5×10-3 to 13×10-3. Comparison with calculations based on classical triton confinement and slowing down in the JET plasma that the data are generally 20% lower than calculated values but still within the overall uncertainties involved.