Tritium is an isotope of hydrogen. It has 1 proton and 2 neutrons which gives it an atomic mass of 3, whereas the most common isotope of hydrogen called protium has just 1 proton and the atomic mass of 1.
It is not possible to convert tritium to copper. Copper is not a chemical compound that contains hydrogen. It is only possible to convert tritium to a compound that has hydrogen as one of its constituents. For example if tritium were combusted, it would combine with oxygen to form tritiated water.
2 T2 + O2 --> 2 T2O
As far as NT3 is concerned, it can be produced by the Haber-Bosch process using magnetite as a catalyst by reacting tritium and nitrogen.
3 T2 + N2 --> 2 NT3
Also, How do you change tritium gas to NT3?