Calibration of a direct nuclear activation diagnostic which uses boron nitride to measure energetic deuterium ions

A direct nuclear activation diagnostic for the measurement of the kinetic e nergy of deuterium ions in the energy range of 1-3 MeV has been successfull y developed. This diagnostic is based on the fact that the ratio of two dif ferent thick-target yields which are generated by the same incident ion spe cies can be a sensitive function of incident ion energy. Targets for this d iagnostic are made of alpha-boron nitride (BN) and use the two reactions: B -10(d,n) C-11(beta+) and N-14(d,n) O-15(beta+). The ratio of thick-target y ields depends only on the deuterium ion energy and is independent of ion fl uence and detector efficiency. The calibrated diagnostic was then fielded t o measure the voltage in a plasma opening switch (POS). Electrical measurem ents of the POS voltage and the voltage inferred from the BN nuclear activa tion diagnostic were in good agreement. (C) 1999 American Institute of Phys ics. [S0034-6748(99)59501-4].